A search of MEDLINE in March 2006 and of The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue 1, 2006) did not yield any additional eligible studies.
The methods and the results sections of the review were entirely revised
according to new Cochrane guidelines for cross-over trials.
Lung disease in babies born early (preterm) is often complicated with excess accumulation of water in the lungs. Medications that reduce body water (diuretics) might help the baby recover from lung disease. In theory, giving the diuretic as an inhaled mist (aerosol) could drain water from the lung more than from the rest of the body, which could reduce adverse effects. The review found several small trials of a single type of diuretic (furosemide). A single dose improved lung function, but only temporarily. No information was available about longterm outcome.
Among preterm infants < 3 weeks of age developing CLD, not enough information is available to assess the effect of aerosolized furosemide on outcome or lung function.
Among infants > 3 weeks with CLD, a single aerosolized dose of 1 mg/kg of furosemide may transiently improve pulmonary mechanics. Not enough information is available to assess the effect of chronic administration of aerosolized furosemide on oxygenation and pulmonary mechanics.
More double-blinded randomized trials are needed (1) to analyze factors likely to affect the response to aerosolized furosemide, e.g., washout period and delivery of furosemide to distal airways, and (2) to assess the effects of chronic administration of aerosolized furosemide on mortality, O2 dependency, ventilator dependency, length of hospital stay and long-term outcome.
1. Rationale for administering aerosolized diuretics to neonates with
CLD:
1.1. Reduction of lung edema:
Early stages of chronic lung disease (CLD) of prematurity are associated
with lung edema. Factors involved in this edema include increased capillary
permeability resulting from lung injury, congestive heart failure due to
patent ductus arteriosus, and fluid overload (Brown 1978; Zimmerman 1995).
This edema could not only reduce pulmonary compliance (and thus tidal volume
if using a pressure-limited ventilator) but also increase airway resistance
by narrowing terminal airways (Northway 1967).
Diuretics may accelerate lung fluid reabsorption and improve pulmonary mechanics
in patients with lung edema via two types of mechanisms: (1) an immediate,
diuresis-independent lung fluid reabsorption, and (2) a delayed increase
in urine output (Brion
1999a). It is possible that the incidence of lung edema in preterm infants
may have decreased as a result of changes in therapy introduced in the last
decade (Gortner
1991; Sonntag
1996).
1.2. Reduction of bronchoconstriction:
Reactive airway disease may result from narrowing of the terminal airways
secondary to interstitial edema (see 1.1) and from bronchial smooth muscle
hypertrophy (Northway
1967). Infants with BPD may develop reactive airway disease (Denjean 1992) and
benefit from bronchodilator therapy. Reactive airway disease in those infants
may persist into childhood (Bader 1987).
Both in children and in adults, aerosolized diuretic administration (furosemide, acetazolamide and amiloride) has been shown to alleviate reactive airway disease mediated by various stimuli (exercise, fog, metabisulfite, antigen) but not bronchoconstriction at rest or that secondary to metacholine challenge (Editorial 1990; O'Donnell 1992; Mochizuki 1995). In contrast, a randomized double-blind, placebo-controlled trial with parallel design failed to show any therapeutic effect of aerosolized furosemide in wheezing infants (Van Bever 1995).
Furosemide decreases smooth muscle contractility in vitro whether applied to the intraluminal (mucosal) or extraluminal side of the airway (Iwamoto 1997). Several possible mechanisms of diuretic action (specifically, furosemide) on airway smooth muscle contractility have been proposed. First, furosemide, by inhibiting the basolateral Na-K-2Cl cotransporter of the epithelial cells (Frizzell 1979; Welsh 1983; Lavallee 1997), could modify the osmotic and ionic environment, thereby possibly affecting the activation of mast cells and sensory epithelial nerves (Bienenstock 1988). Second, furosemide has been shown to decrease the release of inflammatory mediators, including leukotrienes and histamine produced by lung tissue in vitro (Anderson 1991) and interleukin-6 by peripheral blood mononuclear cells (Yuengsrigul 1996). Third, furosemide could release bronchodilator prostaglandins from airway epithelium, as shown with vascular endothelium (Lundergan 1988) or kidney (see Brion 1998). The action of furosemide on bronchospasm has been shown to be reduced by indomethacin by some (Pavord 1992) but not all authors (Rodwell 1997). Finally, loop diuretics could inhibit cholinergic and excitatory non-cholinergic non-adrenergic contraction of bronchial muscle (Elwood 1991).
Therefore, one may speculate that aerosolized diuretic administration might decrease bronchoconstriction in those infants with BPD who also have reactive airway disease.
2. Pharmacokinetics and pharmacodynamics of diuretics:
So far, the only diuretic administered to neonates in aerosolized form
is furosemide. Because of the long half-life of loop diuretics in immature
infants (Peterson 1980;
Vert 1982), a prolonged
washout period (without diuretic administration) is needed if one wishes
to eliminate any residual diuretic activity before initiating a clinical
trial or between exposures in cross-over trials.
Only a small fraction of aerosolized furosemide reaches the terminal bronchioles and alveoli. Medication deposition in the lung may range between 1 and 15% (Fok 1994, O'Riordan 1994). Critical components may include (1) the type of nebulizer, which affects the size of the droplets (2) characteristics of the tubing, including length and temperature gradient, (3) the side flow which if too high will lead to bypassing the patient into the expiratory limb of the tubing, (4) humidity of inhaled gas and (5) whether the patient is ventilated or not (Cameron 1990; Fok TF 1994; Kugelman 1997; O'Riordan 1994, Prabhu 1997).
Unless all these characteristics are provided, it may be difficult to estimate the amount of medication effectively received by the patient. Thus, negative data might result from either lack of efficacy of the medication on the lung, lack of delivery to the distal airway, or both.
Some of the effects on lung function may result from systemic absorption, as shown by increased urine output in some (Aufricht 1997; Seidenberg 1992) but not all studies.
3. Potential toxicity of diuretic administration include the following:
(1) hypovolemia, increased drug-induced nephrotoxicity (resulting at least
in part from hypovolemia), hyponatremia, hypokalemia, hypochloremia, hyperuricemia
and metabolic alkalosis.
(2) hypercalciuria (leading to nephrolithiasis, nephrocalcinosis and bone
demineralization) and hyperphosphaturia (leading to osteopenia)
(3) increased incidence of patent ductus arteriosus
(4) cholelithiasis
(5) neurosensory hearing loss, resulting from high serum levels of furosemide
associated with long half-life in immature infants.
4. Summary and rationale for aerosolized diuretic administration in CLD
in preterm infants:
Diuretic administration could improve pulmonary mechanics by three separate
mechanisms:
-immediate diuresis-independent reabsorption of lung fluid
-decrease in bronchospasm in patients with reactive airway disease
-delayed reabsorption of lung fluid mediated by a decrease in extracellular
volume secondary to increased diuresis
The first two mechanisms would be expected to improve lung mechanics by local action, whereas the third mechanism requires systemic absorption. The rationale for using aerosolized diuretics is to try to alleviate lung disease without causing side effects secondary to systemic absorption.
This review incorporates minor additions in updating the existing review which was published in The Cochrane Library, Disk Issue 3, 1999 (Brion 1999d).
1. Primary outcome variables:
1.1. Short-term improvement: changes in mean airway pressure, need for
artificial ventilation, need for continuous positive airway pressure, failure
to tolerate extubation, and changes in concentration of inhaled oxygen
1.2. Long-term improvement: mortality, duration of need for oxygen supplementation
and respiratory support, BPD, death or BPD, chronic lung disease at 36 weeks
of postconceptional age (gestational age + postnatal age), length of stay,
and number of rehospitalizations during the first year of life.
2. Secondary outcomes:
2.1. Potential complications: Incidence of alkalosis, hyponatremia, hypochloremia,
bone demineralization (measured by using bone radiogram or densitometry),
nephrocalcinosis, nephrolithiasis, cholelithiasis, neurosensory hearing loss.
2.2. Pulmonary function: Changes in resistance, compliance, tidal volume
for patients on pressure-limited ventilation, expiratory flow.
1. Published manuscripts:
We searched MEDLINE (1966 - 1998), EMBASE (1974 - 1998) and the Cochrane
Controlled Trials Register (CCTR) from The Cochrane Library (Issue 3, 1998)
in August 1998. We did not limit the search to any language.
We used the following keywords:{<bronchopulmonary dysplasia> or <chronic
lung disease>}
and <explode diuretics>,
limited to <human> and
limited to <infant, newborn> or <infant>.
Additional searches of MEDLINE done using {<bronchopulmonary dysplasia> or <chronic lung disease>} and <diuretic> in January 2001, April 2003 and April 2006 did not yield any additional eligible studies. Search of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2003 and Issue 1, 2006) did not yield any additional eligible studies.
2. Published abstracts:
We searched the abstracts of the following national or international societies
(1991 - 1998 unless otherwise specified):
# American Academy of Pediatrics 90-98 (published in American Journal of
Perinatology [90-95] and in Pediatrics [96-98])
# American Society of Nephrology (published in Journal of the American
Society of Nephrology)
# American Thoracic Society 91-98 (published in American Review of Respiratory
Disease [91-93] and in American Journal of Respiratory and Critical Care
Medicine [94-98])
# British Paediatric Association (now Royal College of Paediatrics and
Child Health [RCPCH] Annual Scientific Meeting)
# European Respiratory Society
# European Society for Pediatric Research (published in Pediatric Research)
# Neonatal Society [UK]
# Society for Pediatric Research [US] (published in Pediatric Research).
Details of the search can be found in a related review (Brion 1999a).
Additional searches of the abstracts of the UK Neonatal Society and the European Respiratory Society, done up to March 2006, and of the US Society for Pediatric Research (2000-2006) did not yield any additional eligible studies.
3. Database of the Neonatal CRG of the Cochrane Collaboration:
We screened all publications coded under diuretics as intervention in September,
1998.
4. Selection process:
We only kept randomized controlled trials fulfilling the selection criteria
described in the previous section. Selection was done separately by two investigators
(LPB and RP); any disagreement was resolved by discussion.
1. Data extraction and entry:
Two investigators extracted, assessed and coded separately all data for
each study, using a form that had been designed specifically for this review.
We transformed graphical data into numerical data using a millimetric ruler
and an electronic spreadsheet. We replaced any standard error of the mean
by the corresponding standard deviation (SD). As much as possible we homogenized
units among studies; in some cases this required using a specific formula
to estimate the SD of a ratio or a product (Baird 1995; Armitage 1994).
In December 1998, we sent to each author an itemized letter requesting additional information about design, patients, methods, or original outcome data (if missing, incomplete or presented in graphical form). We obtained additional data from three authors: Dr. Ohki, Dr. Kugelman and Dr. Stefano (c/o Ms. Leef). Dr. Ohki kindly provided us with additional data, specifically, mean and standard deviation of measurements of pulmonary mechanics at baseline, one hr and two hr, as well as mean and standard deviation of the values at 1 hr and 2 hr expressed as percent of baseline. Dr. Kugelman provided us with description of methods, other medications received by the patients, and the order of medication administered. Dr. Stefano provided us with information on prior exposure to diuretics, method of aerosolization and ventilator parameters.
All calculations within the spreadsheet and entries into RevMan were done by one review author (LPB) and subsequently checked for accuracy by another review author (WY and RP). Any disagreement was resolved by discussion.
Conversion of values into SI units:
To obtain gas pressure in kPa, we multiplied the value in cm H2O by 0.10
or that in mm Hg by 0.13
To obtain calcium:creatinine ratio in mM:mM, we multiplied the ratio in
mg:mg by 2.84
To obtain calcium in mM/L, we multiplied the value in mg/dl by 0.25
2. Planned comparisons and subgroup analyses:
2.1. We planned the following comparisons based on type of intervention:
2.1.1. Comparison of aerosolized diuretic administration versus placebo
2.1.2. Comparison of aerosolized diuretic administration versus intravenous
administration
2.1.3. Comparison of various doses of furosemide by aerosol
For studies in which controls did not receive placebo but another intervention, we arbitrarily considered as 'control' 1) intravenous administration of furosemide, or 2) intermittent administration of a single diuretic.
2.2. Mean postnatal age:
Within each of the above groups, subgroups were determined based on mean
postnatal age. The initial plan was to use a cut-off value of four wks, based
on the usual definition of bronchopulmonary dysplasia. However, using this
value would have made it impossible to classify two of the twenty studies
included in this group of three related reviews on diuretics in preterm infants
with (or developing) CLD (Singhal 1983; Robbins 1993).Therefore,
we selected a mean postnatal age of three wk as the cut-off for all three
reviews.
2.3. Mean gestational age:
We planned to use subcategories based on mean gestational age if mean values
in various studies were observed to differ by more than four weeks.
2.4. Presence of an endotracheal tube:
Pre-determined sub-categories were used for intubated patients vs. non-intubated
patients. The presence of an endotracheal tube is expected to increase total
resistance and to decrease dead space. Patients requiring an endotracheal
tube are likely to be sicker and thus to have lower pulmonary compliance
and to require more oxygen than the other patients.
3. Criteria for assessing the methodological quality of the studies:
We used the standard method of the Cochrane Neonatal Review Group. We assessed
the methodological quality of the studies by assessing the risk for four
types of bias (selection, performance, attrition and detection). Each study
was assessed separately by two review authors; disagreements were resolved
by discussion with the other review authors.
4. Statistical analysis:
We used the standard method of the Cochrane Neonatal Review Group, using
a fixed effect model.
For dichotomous variables we analyzed the odds ratio (OR) to combine parallel
trials with cross-over trials, using for cross-over trials an alternate odds
ratio approach with an imputed correlation (Elbourne 2002). If
the imputed correlation for all cross-over trials was zero, we analyzed relative
risk (RR) and risk difference (RD).
For continuous variables we combined parallel trials with cross-over trials
using the inverse variance method (Handbook version 4.2.5, pages 117 and
159). We obtained the weighted mean difference (WMD) and its standard error
(using a correlation coefficient of 0.4 for cross-over trials, or 0.3 for
sensitivity analysis) between change scores in the treatment group and in
the control group. Change scores were obtained either from the mean of individual
differences between baseline and final values, from mean and SD (or standard
error) values of change (or percent of baseline) provided by the authors,
or from the means and SD of baseline and final values. In the latter case,
the variance (var) of change was estimated using Follmann's (Follmann 1992)
method, described in version 3.0.2 of the Cochrane Collaboration Handbook
(page 213):
Var(change)=Var(pretest) + Var(posttest) - 2 x SD(pretest) x SD (posttest)
x pretest-posttest correlation coefficient.
We searched the literature for values of pretest-posttest correlation coefficient
(r) for each test, interval and patient group. If such data were not available,
we assumed a value of 0.4, and conducted a sensitivity analysis by successively
using r = 0.3 and r =0.5.
Tests of between-study heterogeneity (chi-square analysis and I squared)
were used to determine if pooling of data was appropriate. If there was
inconsistency in the direction of the effect we presented the data of the
meta-analysis and discussed possible mechanisms involved in heterogeneity
among the studies.
For those studies providing mean and SD of baseline values and of the percent change from baseline, we obtained the mean change by multiplying percent change by the average baseline. Variance of change was calculated using established guidelines (Baird 1995; Armitage 1994), as described elsewhere (Brion 1999a).
Almost all studies included in this review included dynamic measurements of pulmonary mechanics with or without an esophageal balloon. Static measurements were done in only one study (Ohki 1997). Main categories (intervention) are shown as first entry in the column labeled 'Interventions.' No subcategories were used based on gestational age, because the maximum range of gestational age within each intervention group was four weeks. Main categories (based on intervention) and subcategories (based on postnatal age and mechanical ventilation) are described below:
1. Administration of furosemide by aerosol versus placebo:
This group included four studies, one with parallel design (Robbins 1993), and
three with cross-over design (Raval 1994; Ohki 1997; Kugelman 1997). Average
gestational age ranged between 25 and 29 weeks, so that only one group was
considered for the analysis. All patients required mechanical ventilation
at study entry.
1.1. Average postnatal age < 3 weeks
Raval 1994: cross-over
design with pooled data.
This study was available as abstract only; additional data were provided
by the authors. Six infants did not receive any diuretics before the study
period. One patient in the control group had received diuretics two weeks
before the study, and three patients had received one dose of furosemide
during the last five days preceding the study (two in the control group and
one in the treated group). Patients were randomized to receive either a
daily dose of 1 mg/kg of furosemide for two days followed by placebo, or
vice-versa. There was no washout period between the two phases. An 'acorn'
nebulizer with a capillary was placed in line on the ventilator circuit and
the medication was mixed with 2 ml of normal saline and delivered at 6 L/min
flow. The authors measured dynamic pulmonary mechanics. Change scores for
tidal volume were estimated using Follmann's formula.
1.2. Average postnatal age > 3 weeks
Kugelman 1997:
cross-over design with pooled data.
Patients were randomized to receive either a single dose of 1 mg/kg of
furosemide followed by placebo, or vice-versa. The washout period before
the study was only six hours for thiazides, spironolactone, and furosemide.
A 24 hour-washout period was documented at the time of cross-over. Change
scores for tidal volume were estimated using Follmann's formula; those for
compliance, resistance and transcutaneous pO2 were calculated from the authors'
primary data.
Ohki 1997: cross-over
design with pooled data.
Patients were randomized to receive either a single dose of 1 mg/kg of
furosemide followed by a 48-hour washout period and then placebo, or vice-versa.
A washout period of 48 hours was documented both before the study and at
the time of crossover.
In patients on furosemide, change scores for pulmonary function tests were estimated by the mean of two results. First we used Baird and Armitage's method with the exact unpublished average and SD baseline values (see table of included studies) and percent values of baseline provided by Y. Ohki. Second, we calculated the mean of change scores for individual data extracted from figures 4-6. For patients in the control group, only the first method was available. Change scores for blood pH were estimated using Follmann's formula.
Robbins 1993:
parallel design.
This study was available as abstract only. Patients were randomized to
receive either 1 mg/kg of furosemide (the interval is not mentioned in the
abstract) for seven days, or placebo. No washout period was documented.
Change scores for tidal volume were estimated using Follmann's formula.
2. Administration of furosemide by aerosol versus intermittent intravenous
furosemide administration in controls:
This group included two studies (Rastogi 92, Prabhu 97), both with a cross-over
design. Patients in these studies had similar gestational ages (26 - 27 weeks)
and postnatal ages (~ four weeks). All patients required mechanical ventilation
at study entry.
Prabhu 1997:
cross-over design with pooled data.
Patients were randomized to receive either 1 mg/kg of furosemide followed
by placebo, or vice-versa. No patients had received any diuretics before
the study. Bronchodilators were held for four hrs before the study. Change
scores for tidal volume were estimated using Follmann's formula.
Rastogi 1992:
cross-over design with pooled data.
Patients were randomized to receive either 1 mg/kg of furosemide followed
by placebo, or vice-versa. No washout period was documented. Change scores
for tidal volume were estimated using Follmann's formula.
3. Comparison of various doses of aerosolized furosemide:
This group includes two studies (Prabhu 98 and Rastogi 94). They had similar
gestational ages and postnatal ages. One study compared a dose of 1 mg/kg
furosemide with lower doses (Rastogi 94). The other study compared a dose
of 1 mg/kg with 2 mg/kg (Prabhu 98). Therefore, we did not combine these
two studies.
Prabhu 1998:
cross-over design with pooled data.
Patients were randomized to receive either 1 mg/kg followed by 2 mg/kg
of furosemide, or vice-versa. No diuretics or glucocorticosteroids were
used before study in any patient. Bronchodilators were held for four hours
before the study. Change scores for tidal volume were estimated using Follmann's
formula.
Rastogi 1994:
cross-over design with pooled data.
Patients received furosemide at doses of 0.1, 0.25 and 0.5 mg/kg in random
order. A washout period of 72 hr was documented before the study. Serial
values were only provided after a dose of 1 mg/kg, so that change scores
could not be calculated for any of the lower doses.
Ohki 1997:
Randomization and outcome, but not intervention (nurses prepared the medication),
were blinded.
Robbins 1993:
This study was exempt of any of the four types of bias analyzed.
2. Administration of furosemide by aerosol versus intermittent intravenous furosemide administration in controls:
Prabhu 1997:
Blinding is not documented.
Rastogi 1992:
Blinding is not documented.
3. Comparison of various doses:
Prabhu 1998:
Blinding is not documented.
Rastogi 1994:
Blinding was not documented.
Furthermore, for most outcomes, only one or two studies provided data that could be merged into a meta-analysis, so that only a small number of patients was included in each analysis. Therefore, it is possible that real differences due to furosemide administration could have been missed. For each analysis we report the studies and the number of patients in which the particular outcome is reported.
No study assessed the amount of diuretic effectively delivered to the patient.
2. Calculation of WMD and estimation of the pretest-posttest correlation
coefficient (r):
For most variables, r was assumed to be 0.4. Unless specified otherwise,
sensitivity analysis using a value of 0.3 or 0.5 did not significantly alter
the CI and the summary results.
Limited data on dynamic measurements in preterm infants (Kugelman 1997) suggest that r is higher for dynamic compliance (0.8 for a 1-hour or a 2-hour period) than for resistance (0.4 for a 2-hour, 0.7 for a 1-hour period). We used these values in our calculations of change scores with the Follmann's formula for several studies that analyzed the evolution of dynamic pulmonary mechanics over a period of maximum two hours (Prabhu 1997; Prabhu 1998; Rastogi 1992; Robbins 1993). Sensitivity analysis was done using r=0.4 (vs. 0.7-0.8 as the expected value) or 0.3 (vs. 0.4 as the expected value).
Serial data in patients on furosemide (Ohki 1997) yielded a higher value of r for static compliance (0.84 for 1-hour and 0.90 for a 2-hour period) and resistance (0.87 for a 1-hour and 0.91 for a 2-hour period) than for tidal volume (0.48 for a 1-hour and 0.32 for a 2-hour period). We did not use these values of r for calculating change scores; we used instead additional original data provided by Dr. Ohki.
WMD for tidal volume (Kugelman 1997) was calculated using Follmann's formula while assuming r = 0.4 for tidal volume, whereas WMDs for compliance and resistance were calculated from individual differences between baseline and final values. WMDs for Ohki's data were calculated using original mean and SD of percent values from baseline provided by the author.
We report sensitivity analysis only when it affected the results of the study.
Effects of aerosolized furosemide:
Comparison 01: Administration of furosemide by aerosol versus placebo
Introduction:
The effects of a two-day treatment with aerosolized furosemide on pulmonary
mechanics were assessed in 22 patients < 3 weeks of age enrolled in one
study (Raval 1994).
Data on ventilatory support (n = 19 measurements in each group, provided
by Dr. Stefano) showed identical values at the time of entry into the study
and trends toward higher peak pressure, higher PEEP and higher FiO2 after
furosemide administration than after placebo.
The effect of a single dose of furosemide on pulmonary mechanics in patients
> 3 weeks of age was analyzed in three studies (Kugelman 1997; Ohki 1997; Robbins 1993). Measurements
of pulmonary mechanics 30 minutes after furosemide administration were obtained
in only five patients > 3 weeks of age (Robbins 1993). Seventeen
patients were assessed one hour and two hours after aerosol administration
(Kugelman 1997;
Ohki 1997).
One trial assessed the effects of a seven day treatment with a daily dose
of aerosolized furosemide in patients > 3 weeks of age (Robbins 1993).
Outcome 01.01: Change in transcutaneous pO2 and Outcome 01.02: Change
in blood pH
Furosemide administration did not significantly affect transcutaneous pO2
after one and two hours (n = 9 patients) (Kugelman 1997) or
Outcome 01.02 blood pH after one hour (n = 8 patients) (Ohki 1997).
Outcome 01.03: Change in compliance
In patients < 3 weeks of age furosemide significantly decreased
compliance 20 min after a single dose on the second of therapy (WMD -0.21
ml/cm H2O/kg, CI -0.38, -0.04) (Raval 1994).
In patients > 3 weeks of age, furosemide did not significantly affect compliance at 30 minutes (Robbins 1993). It increased compliance at one hour and two hours in one study (Ohki 1997) but not in the other one (Kugelman 1997). Both tests for heterogeneity (chi-square and I-squared) were statistically significant for compliance at one hour and at two hours. Heterogeneity of response to furosemide could have resulted from differences in (1) washout period at study entry (48 hours for Ohki's study vs 6 hours for Kugelman's study) or at the time of cross-over (48 hours vs 24 hours, respectively), (2) blinding of intervention (only in the second study), (3) method of measuring mechanics of the total respiratory system (static for Ohki's study vs. dynamic without esophageal balloon for Kugelman's study), and (4) method of furosemide delivery (ultrasonic nebulizer [Ohki] vs. neonatal nebulizer with a relatively high side flow of 5 - 6 L/min [Kugelman]). Method of furosemide delivery is unlikely to account for heterogeneity, because the neonatal nebulizer used in the second study has been successfully used to deliver other medications, including B2 agonists, ipratropium bromide, and beclomethasone in ventilated infants with BPD (Kugelman 1997). Washout period is unlikely to account to heterogeneity because subgroup analysis of patients randomized to furosemide first and those randomized to placebo first in Kugelman's study (using data kindly provided by Dr. Kugelman) showed similar results.
Outcome 01.04: Change in resistance
Furosemide did not significantly affect resistance in any of the studies
(Kugelman 1997;
Ohki 1997; Raval 1994; Robbins 1993), in
any of the summary statistics or any of the subgroup analyses.
Outcome 01.05: Change in tidal volume
One trials showed no significant effect of furosemide on tidal volume 20
min after the dose. One trial (Kugelman 1997)
showed no significant effect of furosemide on tidal volume, and the other
trial (Ohki 1997)
showed a significant increase in tidal volume after furosemide. Although
meta-analysis showed that furosemide significantly improved tidal volume
after one hour (WMD 1.86 ml/kg, CI 1.14, 2.59) and two hours (1.11 ml/kg,
CI 0.28, 1.94), both the I squared test and the chi-square test showed significant
heterogeneity. Severity of lung disease was similar in both studies (FiO2
0.30 vs 0.35, peak inspiratory pressure 20 vs 22 cm H2O).
Outcome 01.06: Change in minute ventilation
Furosemide did not significantly affect he change in minute ventilation
20 min after the dose, on the second day of treatment, in patients > 3
weeks of age.
Comparison 02: Administration of furosemide by aerosol versus intermittent intravenous furosemide administration in controls
Change in oxygen administration (Outcome 02.01), transcutaneous
oxygen monitoring (Outcome 02.02) and ventilatory settings (Outcome
02.03 - 02.05).
Aerosolized furosemide tended to decrease the percent inspiratory oxygen
and to improve transcutaneous hemoglobin saturation after two hours (n =
19) (Prabhu 1997).
Aerosolized furosemide did not affect peak inspiratory pressure, positive
end expiratory pressure or ventilatory rate two hours after treatment (n
= 19) (Prabhu 1997).
Outcome 02.06: Change in compliance
Compared with intravenous furosemide, aerosolized furosemide tended to
decrease compliance at 30 minutes in one study (Rastogi 1992) and
significantly increased compliance in the other study (Prabhu 1997). Aerosolized
furosemide significantly improved compliance at one hour (WMD 0.15 ml/cm
H2O/kg, CI 0.08, 0.23, n=24 patients) and at two hours (WMD 0.18 ml/cm H2O/kg,
CI 0.09, 0.26, n = 24 patients) (Prabhu 1997, Rastogi 1992). Lack
of significance at four hours (WMD 0.23, CI -0.24, +0.70) may have resulted
from the small number of patients available (n = 5 patients) (Rastogi 1992), from
lack of a washout period, from overestimating the CI by using r = 0.4 in
Follmann's formula, or from other factors that could not be analyzed in this
study available as an abstract only.
Outcome 02.07: Change in resistance
Aerosolized furosemide significantly improved resistance in one study (WMD
-30 cm/L/sec, CI -48, -12) (Prabhu 1997) and tended
to increase resistance in the other study (Rastogi 1992). Meta-analysis
showed no significant effect of aerosolized furosemide compared with intravenous
furosemide on resistance between 30 min and two hours (n = 24). At at 30
min, both statistical tests for heterogeneity (chi-square and I-squared)
were significant. Heterogeneity could have resulted from lack of a washout
period in one study (Rastogi 1992) but
not the other one (Prabhu
1997), or from overestimating the CI using r = 0.4 in Follmann's formula.
Other potential differences could not be analyzed or detected because Rastogi's
study is only available as an abstract. Aerosolized furosemide significantly
reduced resistance at four hours in one study (Rastogi 1992) using
a correlation coefficient of 0.4 for the cross-over trial (WMD -19.3, CI
-36.9, - 1.7) but not using a correlation coefficient of 0.3 (CI -39.7, +
1.1).
Outcome 02.08: Change in tidal volume
Compared with intravenous furosemide, aerosolized furosemide tended to
improve tidal volume at 30 min in one study (Prabhu 1997) and to
worsen tidal volume in the other one (Rastogi 1992). Meta-analysis
showed significant heterogeneity using the I-squared test but not the chi-square
test. Aerosolized furosemide significantly improved tidal volume at one hour
using a correlation coefficient of 0.4 for the cross-over trial (WMD 1.34
ml/kg, CI 0.12, +2.57, n = 24 patients) but not using a correlation coefficient
of 0.3 (CI -0.07,+2.75) (Prabhu 1997; Rastogi 1992). Aerosolized
furosemide significantly improved tidal volume at two hours (WMD 1.8 ml/kg,
CI 0.5, 3.1, n = 24) but not at four hours (n = 5) (Rastogi 1992).
Comparison 03: 1 mg/kg aerosolized furosemide versus lower doses:
One study compared the effects of 1 mg/kg of furosemide with those
of lower doses (n = 8 patients) (Rastogi 1994).
Outcomes 03.01 - 03.03: Failure to improve pulmonary function
The authors found no effect of low doses of furosemide on pulmonary function,
in contrast with a standard dose of 1 mg/kg. For this review, we arbitrary
limited data entry into MetaView to data corresponding to 1.0 mg/kg (treatment)
vs. 0.1 mg/kg (control). Results on pulmonary function would have been similar
with any of the other low doses. Since no patient responded to the low dose,
the imputed correlation was zero; therefore, we used the values calculated
by RevMan for relative risk (RR) and risk difference (RD). In comparison
with the lower dose, the standard dose of 1 mg/kg of furosemide significantly
decreased the risk of failure to improve compliance within 30 minutes (RR
0.13, CI 0.02, 0.78; RD -0.88, CI -1.16, -0.59) and 4 hours (RR 0.25, CI
0.08, 0.83; RD -0.75, CI -1.08, -0.42). The dose of 1 mg/kg decreased the
risk of failure to improve resistance within 30 minutes (RR 0.13, CI 0.02,0.78;
RD -0.88, CI -1.16, -0.59) and four hours (RR 0.13, CI 0.02,0.78; RD -0.88,
CI -1.16, -0.59). The dose of 1 mg/kg decreased the risk of failure to improve
tidal volume within 30 minutes (RR 0.06, CI 0.00, 0.87; RD -1.00, CI -1.21,
-0.79) and four hours (RR 0.25, CI 0.08, 0.83; RD -0.75, CI -1.08, -0.42).
Outcomes 03.04 and 03.05: Urinary calcium excretion
Administration of a 1 mg/kg dose of aerosolized furosemide did not significantly
affect 24-hour calciuria or urine calcium:creatinine ratio compared with
a lower dose of furosemide.
Comparison 04: 2 mg/kg aerosolized furosemide versus lower doses:
A single studied analyzed the effects of the standard dose of 1 mg/kg
with a higher dose of 2 mg/kg on pulmonary mechanics (n = 13 patients) (Prabhu 1998).
Outcome 04.01: Change in compliance
In comparison with the lower dose, the dose of 2 mg/kg of furosemide significantly
increased compliance after 2 hours using a correlation coefficient of 0.4
for the cross-over trial (WMD 0.10, CI 0.01,0.19) but not using a correlation
coefficient of 0.3 (CI -0.07,+0.27). No significant difference was observed
after four and six hours.
Outcome 04.02: Change in resistance
In comparison with the lower dose, the dose of 2 mg/kg of furosemide did
not significantly affect resistance after 30 minutes or after six hours.
It significantly increased resistance after four hours (WMD 37 cm/L/sec,
CI 2.25, 71.75) using a correlation coefficient of 0.4 for the cross-over
trial, but not using a correlation coefficient of 0.3 (CI -2.77, + 76.77).
Outcome 04.03: Change in tidal volume
In comparison with the lower dose, the dose of 2 mg/kg of furosemide did
not significantly affect tidal volume.
Outcome 04.04: Change in urine output
The higher dose tended to increase urine output compared with the lower
dose, but this did not reach statistical significance.
1.2. Limitations of this review:
Outcomes analyzed:
Most studies focused on pathophysiological parameters, e.g., pulmonary
mechanics, and did not assess the most important outcomes defined in this
review or the potential complications of diuretic therapy.
Methods used for the analysis:
We used the methods recommended by the Cochrane Neonatal Review Group.
For almost all studies, we did not have access to the original data. Therefore,
we used multiple transformations using formulae established by or derived
from Follmann, Baird, and Armitage. Calculations using Baird and Armitage
overestimate the SD of the final variable if the numerator is related to
the denominator, because they assume lack of correlation between them.
For calculations using Follman's formula, we usually assumed an pretest-posttest correlation of 0.4 and did a sensitivity analysis using a correlation coefficient of 0.3. We only used other values for r if they were available for preterm infants of similar size and age, for an identical test (e.g., compliance) performed at similar time intervals and using the same method. We have found higher values of average correlation coefficient for serial dynamic measurements of tidal volume (r = 0.72), compliance (r = 0.92) and resistance (r = 0.80) in full-term infants over a period of 66 hours (Goyal 1995). We are unaware of similar data in very low birth weight infants. Therefore, in this review we may have overestimated the SD of long-term change scores for pulmonary mechanics, especially compliance. Therefore, the results are likely to be conservative, i.e., confidence intervals may be wider than they should be.
Heterogeneity:
Within each subgroup, we used chi-square analysis to test for statistical
evidence of heterogeneity among studies. When heterogeneity analysis was
significant, we analyzed differences (in patient selection, baseline values,
bias, design and methods) among studies that could possibly explain the heterogeneity.
Heterogeneity in response did not appear to result from differences in
methods used for pulmonary function tests. Dynamic measurements were obtained
in three (Prabhu 1997,
Rastogi 1992, Rastogi
94) of four studies showing a transient improvement of pulmonary mechanics
1 - 2 hours after a single dose of furosemide on pulmonary mechanics and
in the single study showing no effect (Kugelman 1997). Static
measurements were obtained in one study, which showed a transient improvement
in pulmonary mechanics after furosemide (Ohki 1997). The reader
is referred elsewhere (Brion 1999a) for further
discussion of methods of measuring pulmonary mechanics.
Because of the long half-life of loop diuretics in immature infants, a prolonged washout period is required to eliminate all diuretic effect before initiating a study or between exposures in a cross-over study. However, a prolonged washout period may not be possible or ethically acceptable for patients considered clinically to require diuretics. Several studies had a short or no washout period, thereby possibly decreasing the apparent effect of diuretic administration on short- and long-term outcome. All cross-over trials failed to provide information that would rule out a carry-over effect (possibly yielding an underestimation of the real effect of diuretic administration) and a period effect.
All studies failed to demonstrate actual delivery of furosemide to the distal airways. None measured the percent recovery of furosemide in the expiratory tubing or serum levels of furosemide.
Sample size:
Because of small sample size in most of the subgroups, any real effects
of furosemide may have remained undetected.
2. Group-specific comments:
Studies only included intubated patients.
In infants < 3 weeks of age, available evidence (single study, pulmonary mechanics measured only after 20 minutes, abstract only) shows no benefit of a two-day course of aerosolized furosemide.
In infants > 3 weeks of age, a single aerosolized dose of 1 mg/kg of furosemide transiently (at 1 - 2 hours) improves compliance compared with intravenous furosemide but does not affect resistance or tidal volume. Four of six studies have shown that a single dose of 1 mg/kg of aerosolized furosemide was more effective in transiently improving compliance than placebo, iv furosemide or a lower dose of aerosolized furosemide. The single study assessing the effect of chronic administration of a daily dose of aerosolized furosemide showed no effect on pulmonary mechanics. This study was published as an abstract only, had no documented washout period, and included only 10 patients.
Double-blinded studies are needed (1) to analyze factors likely to affect the response to aerosolized diuretics, e.g., washout period and delivery of furosemide to distal airways, and (2) to assess the effects of chronic administration of aerosolized diuretics on O2- and ventilator-dependency and long-term outcome.
In infants > 3 weeks of age with CLD, a single aerosolized dose of 1 mg/kg of furosemide may transiently improve pulmonary mechanics. There is no evidence to support any benefit of aerosolized diuretic administration on need for ventilatory support, length of stay, survival or long-term outcome. In view of the lack of data from randomized trials concerning effects on important clinical outcomes, routine or sustained use of aerosolized loop diuretics in infants with (or developing) CLD cannot be justified based on current evidence.
| Study | Methods | Participants | Interventions | Outcomes | Notes | Allocation concealment |
| Kugelman 1997 | Blinding of randomization: yes Blinding of intervention: yes Complete follow up: yes Blinding of outcome: yes Randomized clinical trial, cross-over design with pooled data Washout period (thiazides, spironolactone, furosemide, albuterol, aminophylline): 6 hr before the study; 24 hours at cross-over |
Number of patients entered into the study: n=9 Mechanical ventilation Entry criteria: birth weight 500-2500 g, gestational age maximum 32 weeks, persistent respiratory failure requiring mechanical ventilation and > 30% O2 at 21 days of life, radiographic changes consistent with BPD. Exclusion criteria: proven sepsis, cardiac disease (except patent ductus arteriosus), unstable clinical status. Average birth weight was 1.1±0.3 kg, gestational age 29±3 weeks, postnatal age 47±18 days, postconceptional age 35.7±4.0 weeks and study weight 1.8±0.6 kg. Serum electrolyte concentrations were normal. Six patients were receiving albuterol aerosols and one was receiving aminophylline. Seven were being treated with iv furosemide, one of whom was also receiving thiazide and spironolactone. All these medications were stopped at least 6 hours before the study. No patients received dexamethasone for prevention or treatment of BPD. Ventilatory settings were similar on each day of the study: FiO2 0.35±0.06 vs 0.36±0.09, on day of furosemide administration and on the day of placebo administration, respectively. Peak inspiratory pressure was 22.8±2.4 and 22.4±2.4 cm H2O, positive end expiratory pressure 3.8±0.6 cm H2O in both groups, and ventilator rate 19.7±10.5 and 19.3±11.7 breaths per minute. |
Aerosolized furosemide vs placebo Diuretics and bronchodilators were held for 6 hours before the study. Patients were randomly allocated to receive either 1 dose of aerosolized furosemide 1 mg/kg in 2 ml of normal saline followed by placebo within 24 hours, or vice versa. |
Main outcome: Pulmonary mechanics Secondary outcome: transcutaneous pO2 and pCO2 Measurements of compliance, resistance, pO2 and pCO2 obtained after furosemide were not statistically significant from those after placebo. |
Nebulization was done using a neonatal nebulizer (Adaptor Kit,
Hudson RCI, Temecula, CA) (providing 1-2.1 µm-droplets) placed 10-12
cm from the endotracheal tube on the inspiratory limb of the ventilator,
using a side flow of 5-6 L/min. Ventilator conditions were kept constant
during treatment. Pulmonary mechanics were assessed at baseline, and 1 hour and 2 hours after the aerosol. The authors measured dynamic compliance and resistance using the two-factor least mean square analysis, without an esophageal balloon. |
A |
| Ohki 1997 | Blinding of randomization: yes Blinding of intervention: no (nurses prepared the medication) Complete follow up: yes Blinding of outcome: yes Randomized clinical trial, cross-over design with pooled data Washout 48 hours before the study and 48 hours at crossover |
Number of patients entered into the study: n=8 Mechanical ventilation Entry criteria: Birthweight < 1500 g, respiratory distress requiring mechanical ventilation for > 14 days, chest radiographic evidence of chronic lung disease, no administration of diuretics for at least 48 hour before the start of the study. Exclusion criteria: evidence of congenital malformations, patent ductus arteriosus, congenital heart disease, sepsis or pneumonia. Eight infants were randomized, 6 girls and 2 boys. Average birth weight was 798±225 g and gestational age 26.5±1.9 weeks. Six of 8 patients had received surfactant for RDS. At the time of study postnatal age was 32±15 days, postconceptional age 29.3±1.5 weeks, weight 807±236 g, peak pressure 20±7 cm H2O, ventilatory rate 20±7, FiO2 0.30±0.08, paO2 65.0±13.2 mm Hg and paCO2 50.5±4.5 mm Hg. |
Aerosolized furosemide versus placebo Patients were randomly allocated to receive either a single dose of aerosolized furosemide 2 mg/kg diluted in 3 ml of normal saline, followed after 48 hours by placebo, or vice versa. |
Main outcome: static compliance, resistance and tidal volume. Furosemide administration was followed by a significant increase in compliance from 0.77±0.22 ml/cm/kg initially to 0.94±0.24 ml/m/kg after 1 hour and 0.92±0.18 after 2 hours; compliance did not change after placebo (corresponding values, 0.86±0.21 ml/cm/kg, 0.84±0.16 and 0.85±0.20 ml/cm/kg). Furosemide was also followed by an increase in tidal volume from 7.51±1.26 ml/kg to 9.71±1.70 after 1 hour and 9.59±2.05 after 2 hours. Tidal volume did not change after placebo (corresponding values, 8.71±1.83, 8.70±1.88 and 8.50±1.63). Neither furosemide nor placebo induced any change in resistance; baseline value in the furosemide group was 276.2±96.7 cm H2O/L/sec, and that for the control group was 250.8±95.0 cm H2O/L/sec. |
Nebulization was done using an ultrasonic nebulizer placed in the
inspiratory limb of the ventilator circuit. Pulmonary mechanics were measured at baseline and at 1 and 2 hours after aerosol administration. The authors measured static pulmonary mechanics using the passive occlusion technique. |
A |
| Prabhu 1997 | Blinding of randomization: no Blinding of intervention: no Complete follow up: yes Blinding of outcome: no Randomized clinical trial, cross-over design with pooled data Washout period: bronchodilators 4 hr before study; no diuretics used before study |
Number of patients entered into the study: n=19 Mechanical ventilation. Entry criteria: (1) neonate ventilated and O2-dependent for 14 or more days since birth for primary lung disease, (2) decision by physician caring for the infant to initiate diuretic treatment with furosemide. Exclusion criteria: glucocorticosteroids or diuretics before or during the study. Nineteen patients were randomized, including 6 girls and 13 boys. Eleven were randomized to receive iv furosemide first. Average birth weight was 800±170 g, gestational age 26.2±2.1 weeks, postnatal age 27±11 days, postconceptional age 30.0±2.4 weeks and weight at the time of the study 910±180 g. FiO2 before aerosolized furosemide was 0.45±0.13 vs 0.37±0.13 before intravenous furosemide. Peak pressure was 17.7±2.5 and 17.8±2.7 cm H2O, respectively, PEEP was 5.0±0.7 cm for both, and rate of mechanical ventilation was 26±13 and 29±17 breaths/ min. |
Aerosolized furosemide vs iv furosemide Patients were randomized to receive either 1 dose of aerosolized furosemide 1 mg/kg followed within 24 hours by 1 dose of intravenous furosemide 1 mg/kg, or vice versa. Nebulized bronchodilator (adrenergic) therapy was withheld for 4 hours before and during the 2 hours after furosemide administration. Infants who were receiving theophylline continued to receive it during the study. However, no infant was started on theophylline during the study. |
Main outcome: pulmonary function, fluid and electrolyte
balance. Administration of aerosolized furosemide did not affect ventilatory settings or FiO2 compared to intravenous administration, but significantly reduced urine output (p<0.01) and excretion of Na (p<0.01) and Cl (p<0.01). Repeated measures analysis of variance showed significant increase in tidal volume and in compliance but no change in resistance in after nebulized furosemide; no significant change from baseline was observed after intravenous furosemide. The % change in tidal volume from baseline was higher after aerosolized furosemide than after intravenous administration, both at 30 min (p<0.05) and at 120 min (p<0.01) but not at 60 min. Compliance was higher after aerosolized furosemide than after intravenous administration at 60 min (p<0.05) and 120 min (p<0.01) but not at 30 min. |
Furosemide was provided by using a commercial nebulizer connected
to the inspiratory limb of ventilatory circuit. The entire dose was
administered at a flow of 2 l/min over 5-10 min. Pulmonary function tests were obtained at baseline and at 30 min, 1hr and 2 hr after furosemide administration, whereas the other variables were obtained at baseline and 2 hours after furosemide administration. Pulmonary mechanics were measured using the two-factor, least mean square technique without an esophageal balloon. |
D |
| Prabhu 1998 | Blinding of randomization: not documented Blinding of intervention: not documented Complete follow up: yes Blinding of outcome: not documented Randomized clinical trial, cross-over design with pooled data Washout period: bronchodilators 4 hr before study; no diuretics or glucocorticosteroids used before study in any patient |
Number of patients entered into the study: n=13 Mechanical ventilation Entry criteria: Prematurity, requirement of oxygen and mechanical ventilation for primary lung disease for at least 14 days Exclusion criteria: major congenital anomalies Mean birth weight was 713±132 g, gestational age 25.4±1.5 weeks, postnatal age 24±9.5 days and postconceptional age 28.8±2.0 weeks. Baseline values of compliance, tidal volume, resistance and urine output before the 2 mg/kg dose were similar to those before the 1 mg/kg dose. |
Aerosolized furosemide 2 mg/kg vs 1 mg/kg Patients were randomized to receive either aerosolized furosemide 1 mg/kg once, followed by a 2 mg/kg dose after 24 hours, or vice versa. |
Main outcome: magnitude and duration (beyond 2 hours) of the effects
of furosemide on pulmonary mechanics. Secondary outcome:urine output and urinary excretion of electrolytes. Repeated measures ANOVA showed that both doses significantly increased compliance and tidal volume for up to 6 hours. The 2 doses of furosemide yielded non significantly different values of compliance and tidal volume at 2, 4 and 6 hours. Furosemide administration was not followed by any significant change in urinary output or urinary electrolyte excretion after either dose of furosemide. |
Furosemide was nebulized via the inspiratory limb of the ventilator
circuit, using a flow of 2 L/min and a nebulizer (MiniHeart, Vortran
Medical Technology). Pulmonary function tests were obtained at baseline and at 2,4 and 6 hours after administration of the aerosol. Pulmonary mechanics were measured using the two-factor, least mean square technique without an esophageal balloon. Urine was collected for six hours before and six hours after aerosol administration. Theophylline was continued in those infants already on this medication before the study; no infant was started on theophylline during the 2-day study period. |
D |
| Rastogi 1992 | Blinding of randomization: no Blinding of intervention: no Complete follow up: yes Blinding of outcome: no Randomized clinical trial, cross-over design with pooled data No washout period documented |
Number of patients entered into the study: n=5 Mechanical ventilation Inclusion criteria: Infant with BPD, ventilator dependent Mean birth weight was 743±168 g, gestational age 27±1.8 weeks, postnatal age 30.6±4.3 days and postconceptional age 31.4±1.9 weeks. Baseline compliance before nebulized furosemide tended to be 18% higher than baseline before iv furosemide. Baseline tidal volume and resistance had baselines before nebulized furosemide that were similar to those before iv furosemide. |
Aersolized furosemide vs iv furosemide Patients were randomly allocated to receive either nebulized furosemide 1 mg/kg followed by intravenous furosemide 1 mg/kg, or vice versa. |
Main outcome: pulmonary function tests Resistance was not affected by the route of administration of furosemide. Compliance 2 hours (but not at other times) after nebulized furosemide was significantly higher than after intravenous furosemide. Tidal volume 4 hours (but not at other times) after nebulized furosemide was significantly higher than after intravenous furosemide. However, average % changes from baseline after nebulized furosemide were not significantly different from those after intravenous furosemide. |
Abstract form only; incomplete information available. Pulmonary function tests were measured 1/2, 1, 2 and 4 hours after aerosol administration. Units and methods are not provided; they were assumed to be the same as in one manuscript (Rastogi 1994), in which dynamic compliance (ml/cm H2O/kg) and resistance (cm/L/sec) were measured by the least mean square method. |
D |
| Rastogi 1994 | Blinding of randomization: no. Randomization was obtained using
a table of random numbers. Blinding of intervention: no Complete follow-up: yes. Of 11 eligible infants, informed consent was denied in 3. All of 8 enrolled infants were followed throughout the study. Blinding of outcome: no Randomized clinical trial, cross-over design with pooled data. Washout: 72 hr before delivery; 24 hr at cross-over |
Number of patients entered into the study: n=8 Mechanical ventilation Entry criteria: history of RDS requiring mechanical ventilation at birth, postnatal age > 14 days, persistence of respiratory failure and dependence on O2 and mechanical ventilation, radiographic evidence of chronic pulmonary parenchymal disease, no drug therapy other than vitamins for at least 72 hours before the start of the study Exclusion criteria: evidence of congenital malformations, infection, congenital heart defect, or congenital heart disease. Mean birth weight was 815±297 g and mean gestational age was 27.4±1.6 weeks. At the time of the study, postnatal age was 33±13 days, postconceptional age 32.1±2.5 weeks and weight 1013±331 g. Mean peak inspiratory pressure was 19.3±1.0 cm H2O, mean airway pressure 7.9±1.5 cm, FiO2 0.45±0.17, and ventilatory rate 30±12 per minute. Blood pH was 7.33±0.07 and pCO2 was 44±8 mm Hg. |
Aerosolized furosemide 0.1 vs 0.25, 0.5 ,1 mg/kg Patients successively received in random order four different doses of aerosolized furosemide: 0.1 mg/kg, 0.25 mg/kg, 0.5 mg/kg and 1 mg/kg. Furosemide was made up to a final volume of 2 ml with 0.9% NaCl. |
Compliance improved in 0/8 patients after a low dose of furosemide, compared to 7/8 at 30 minutes and 6/8 at 4 hours after a dose of 1 mg/kg. Resistance decreased in 0/8 patients after a low dose of furosemide, compared to 7/8 at 30 minutes and at 4 hours after a dose of 1 mg/kg. Tidal volume increased in 0/8 patients after a low dose of furosemide, compared to 8/8 at 30 minutes and 6/8 at 4 hours after a dose of 1 mg/kg. Urine output, urinary calcium, calcium/creatinine ratio, fractional excretion of sodium and creatinine clearance were similar after each of the 4 doses of furosemide, suggesting that aerosolized furosemide had no effect on the kidney. | There is no information about efficacy of the method of nebulization,
so that the exact amount of drug reaching the distal airways is not
sure. Pulmonary function was measured at baseline, then at 30 min, 1,2 and 4 hours after aerosol administration. Pulmonary mechanics were measured using the least mean square method. The FiO2 was adjusted during measurement of pulmonary mechanics to maintain hemoglobin saturation >94 %. Patients did not receive sedation; most were in quiet but active sleep state during testing. Urine was collected for 24 hours after each dose of diuretic. The authors state that doses of 0.1-0.5 mg/kg had no effect on pulmonary function; however, no data are provided, so this information cannot be used for meta-analysis. Furthermore, no data are provided to support that a dose of furosemide of 0.1 mg/kg had no effect on urine output. For this meta-analysis, we assumed that 0.1 mg/kg of furosemide had no significant effect on any of the variables and thus can be considered as a placebo. |
D |
| Raval 1994 | Blinding of randomization: yes Blinding of intervention: yes Complete follow up: yes Blinding of outcome: yes Randomized clinical trial, cross-over design with pooled data No washout period documented |
Number of patients entered into the study: n=11 Mechanical ventilation Inclusion criteria: BPD, ventilator-dependent premature infant with postnatal age at least 14 days Average birth weight was 780±207 g, gestational age 25±1 wk, postnatal age 19±10 days and postconceptional age 27.7±1.7 weeks. Baseline values of compliance, resistance, tidal volume and minute ventilation before furosemide were similar to those before placebo. |
Aerosolized furosemide vs placebo Patients were randomly allocated to receive aerosolized furosemide 1 mg/kg in 2 ml of normal saline twice q 24 hours followed by placebo twice q 24 hours, or vice versa. |
Main outcome: pulmonary mechanics: compliance, resistance, tidal
volume, minute ventilation. There was no significant difference in any of the variables after furosemide versus after placebo. |
Abstract form only; no information available about type of nebulizer,
flow, and other medications. Dynamic pulmonary function tests were obtained 20 minutes before and 20 minutes after treatment. |
A |
| Robbins 1993 | Blinding of randomization: yes Blinding of intervention: yes Complete follow up: yes Blinding of outcome: yes Randomized clinical trial, parallel design No washout period documented |
Number of patients entered into the study: n=10 Mechanical ventilation Inclusion criteria: BPD Of 10 patients, five were allocated to each group. There was no significant difference between the two groups in any of the variables analyzed. Average birth weight was similar in furosemide-treated patients and in those on placebo, 671±136 g and 786±242, g respectively. Mean gestational age was, respectively, 26.2±1.8 and 26.2±1.3 weeks, mean weight at entry 850±179 and 944±293 g, mean postnatal age 31±13 and 24±7 days, and postconceptional age 30.6±2.6 and 29.6±1.6 weeks, respectively. Peak inspiratory pressure was similar in both groups (20.2±1.8 vs 19.6±1.8 cm H2O), so were positive end expiratory pressure (5.2±1.1 and 5.0±1.0 cm) and FiO2 (0.41±0.25 and 0.41±20). |
Aerosolized furosemide vs placebo Patients were randomly allocated to receive either aerosolized furosemide 1 mg/kg in 2 ml normal saline or placebo (normal saline) for seven days. The interval of administration is not stated in the abstract. |
Main outcome: pulmonary mechanics. There was no significant difference in compliance or in resistance between the two groups. |
Abstract form only; no information available about frequency of
administration, type of nebulizer, flow, other medications. Pulmonary function tests (dynamic compliance and resistance) were obtained 15 minutes before aerosol, 30 minutes after the first dose and again on day 7 before the aerosol. |
A |
| Study | Reason for exclusion |
| Suresh 1992 | Not a randomized study |
* Kugelman A, Durand M, Garg M. Pulmonary effect of inhaled furosemide in ventilated infants with severe bronchopulmonary dysplasia. Pediatrics 1997;99:71-75.
Kugelman A, Durand M, Garg M. Pulmonary effect of inhaled furosemide in ventilated infants with severe bronchopulmonary dysplasia [letter]. Pediatrics 1997;100:420-1.
Kugelman A, Durand M, Saiki K, Platzker ACG, Garg M. Effects of inhaled furosemide in ventilated infants with bronchopulmonary dysplasia. American Journal of Respirology and Critical Care Medicine 1994;149:A546.
Ohki 1997 {published data only}
Ohki Y, Nako Y, Koizumi T, Morikawa A. The effect of aerosolized furosemide in infants with chronic lung disease. Acta Paediatrica 1997;86:656-60.
Prabhu 1997 {published data only}
Prabhu V, Keszler M, Dhanireddy R. Effects of nebulized versus intravenous furosemide on pulmonary function in infants with chronic lung disease [abstract]. Pediatric Research 1995;37:346A.
Prabhu VG, Dhanireddy R. Pulmonary effect of inhaled furosemide in ventilated infants with severe bronchopulmonary dysplasia [letter]. Pediatrics 1997;100:420.
* Prabhu VG, Keszler M, Dhanireddy R. Pulmonary function changes after nebulised and intravenous frusemide in ventilated premature infants. Archives of Disease in Childhood Fetal & Neonatal Edition 1997;77:F32-5.
Prabhu 1998 {published data only}
Prabhu VG, Keszler M, Dhanireddy R. Comparison of two different doses of nebulized furosemide on pulmonary function in infants with chronic lung disease [abstract]. Pediatric Research 1996;39:346A.
* Prabhu VG, Keszler M, Dhanireddy R. Dose-dependent evaluation of the effects of nebulized furosemide on pulmonary function in ventilated infants. Journal of Perinatology 1998;18:357-60.
Rastogi 1992 {published data only}
Rastogi A, Luayon M, Ajayi O, Pildes RS. Nebulized furosemide therapy vs iv furosemide in infants with BPD - A preliminary report [abstract]. Pediatric Research 1992;31:218A.
Rastogi 1994 {published data only}
Luayon O, Rastogi A, Ajayi O, Pildes RS. Nebulized furosemide therapy in infants with BPD [abstract]. Pediatric Research 1992;31:315A.
* Rastogi A, Luayon M, Ajayi OA, Pildes RS. Nebulized furosemide in infants with bronchopulmonary dysplasia. Journal of Pediatrics 1994;125:976-9.
Raval 1994 {published data only}
Raval NC, Leef KH, Antunes MJ, Stefano JL. Effect of aerosolized furosemide on pulmonary function in infants with BPD: A randomized, blinded placebo controlled trial [abstract]. Pediatric Research 1994;35:350A.
Robbins 1993 {published data only}
Robbins G, Tayaba R, Ochshorn IL, Green RS, Holzman IR. Effects of nebulized furosemide vs normal saline on pulmonary mechanics in bronchopulmonary dysplasia [abstract]. Pediatric Research 1993;33:233A.
Suresh BR, Brion LP, Goyal M, Fleischman AR. Acute effects of aerosolized furosemide on pulmonary function in low birth weight infants with chronic lung disease [abstract]. Pediatric Research 1992;31:324A.
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| Comparison or outcome | Studies | Participants | Statistical method | Effect size |
|---|---|---|---|---|
| 01 Aerosolized furosemide vs. control | ||||
| 01 Change in transcutaneous pO2 (mm Hg), patients > 3 weeks of age | WMD (fixed), 95% CI | Subtotals only | ||
| 02 Change in blood pH, 1 hour after 1 dose, patients > 3 weeks of age | 1 | 16 | WMD (fixed), 95% CI | 0.00 [-0.02, 0.02] |
| 03 Change in compliance (ml/cm H2O/kg) | WMD (fixed), 95% CI | Subtotals only | ||
| 04 Change in resistance (cm/L/sec) | WMD (fixed), 95% CI | Subtotals only | ||
| 05 Change in tidal volume (ml/kg) | WMD (fixed), 95% CI | Subtotals only | ||
| 06 Change in minute ventilation (ml/kg/min) 20 min after dose, on 2nd day, > 3 weeks of age | WMD (fixed), 95% CI | Subtotals only | ||
| 02 Aerosolized furosemide vs. intravenous furosemide | ||||
| 01 Change in % inspiratory O2 2 hours after 1 dose | WMD (fixed), 95% CI | Subtotals only | ||
| 02 Change in trancutaneous O2 saturation (%) 2 hours after 1 dose | WMD (fixed), 95% CI | Subtotals only | ||
| 03 Change in peak inspiratory pressure (cm H2O) 2 hours after 1 dose | WMD (fixed), 95% CI | Subtotals only | ||
| 04 Change in positive end expiratory pressure (cm H2O) 2 hours after 1 dose | WMD (fixed), 95% CI | Subtotals only | ||
| 05 Change in ventilator rate (cycles per minute) 2 hours after 1 dose | WMD (fixed), 95% CI | Subtotals only | ||
| 06 Change in compliance (ml/cm H2O/kg) | WMD (fixed), 95% CI | Subtotals only | ||
| 07 Change in resistance (cm/L/sec) | WMD (fixed), 95% CI | Subtotals only | ||
| 08 Change in tidal volume (ml/kg) | WMD (fixed), 95% CI | Subtotals only | ||
| 03 1 mg/kg aerosolized furosemide (Treatment) vs. lower dose (Control) | ||||
| 01 Failure to improve compliance | RR (fixed), 95% CI | Subtotals only | ||
| 02 Failure to improve resistance | RR (fixed), 95% CI | Subtotals only | ||
| 03 Failure to improve tidal volume | RR (fixed), 95% CI | Subtotals only | ||
| 04 Urinary calcium (mg/kg/day) over 24 hours | WMD (fixed), 95% CI | Subtotals only | ||
| 05 Calcium:creatinine ratio (mg:mg) | WMD (fixed), 95% CI | Subtotals only | ||
| 04 2 mg/kg aerosolized furosemide (Treatment) with 1 mg/kg (Control) | ||||
| 01 Change in compliance (ml/cm H2O/kg) | WMD (fixed), 95% CI | Subtotals only | ||
| 02 Change in resistance (cm/L/sec) | WMD (fixed), 95% CI | Subtotals only | ||
| 03 Change in tidal volume (ml/kg) | WMD (fixed), 95% CI | Subtotals only | ||
| 04 Change in urine output | WMD (fixed), 95% CI | Subtotals only | ||
01.01 Change in transcutaneous pO2 (mm Hg), patients > 3 weeks of age
01.01.01 1 hour after single dose
01.01.02 2 hours after single dose
01.02 Change in blood pH, 1 hour after 1 dose, patients > 3 weeks of age
01.03 Change in compliance (ml/cm H2O/kg)
01.03.01 20 min after single dose, on second day, patients < 3 weeks
of age
01.03.02 30 min after a single dose, patients > 3 weeks of age
01.03.03 1 hour after single dose, patients > 3 weeks of age
01.03.04 2 hours after single dose, patients > 3 weeks of age
01.03.05 Before therapy, on seventh day of therapy, patients > 3 weeks
of age
01.04 Change in resistance (cm/L/sec)
01.04.01 20 min after a single dose, on second day, patients < 3 weeks
of age
01.04.02 30 min after single dose, patients > 3 weeks
01.04.03 1 hour after single dose, patients > 3 weeks of age
01.04.04 2 hours after single dose, patients > 3 weeks
01.04.05 2 hours after single dose, furosemide first
01.04.06 2 hours after single dose, furosemide second
01.04.07 Before therapy, on seventh day of therapy, patients > 3 weeks
01.05 Change in tidal volume (ml/kg)
01.05.01 20 min after dose, on second day, patients < 3 weeks of age
01.05.02 1 hour after single dose, patients > 3 weeks of age
01.05.03 2 hours after single dose, patients > 3 weeks of age
01.06 Change in minute ventilation (ml/kg/min) 20 min after dose, on 2nd day, > 3 weeks of age
02 Aerosolized furosemide vs. intravenous furosemide
02.01 Change in % inspiratory O2 2 hours after 1 dose
02.02 Change in trancutaneous O2 saturation (%) 2 hours after 1 dose
02.03 Change in peak inspiratory pressure (cm H2O) 2 hours after 1 dose
02.04 Change in positive end expiratory pressure (cm H2O) 2 hours after 1 dose
02.05 Change in ventilator rate (cycles per minute) 2 hours after 1 dose
02.06 Change in compliance (ml/cm H2O/kg)
02.06.01 30 min after single dose
02.06.02 1 hour after single dose
02.06.03 2 hours after single dose
02.06.04 4 hours after single dose
02.07 Change in resistance (cm/L/sec)
02.07.01 30 min after a single dose
02.07.02 1 hour after a single dose
02.07.03 2 hours after a single dose
02.07.04 4 hours after a single dose
02.08 Change in tidal volume (ml/kg)
02.08.01 30 min after single dose
02.08.02 1 hour after single dose
02.08.03 2 hours after single dose
02.08.04 4 hours after single dose
03 1 mg/kg aerosolized furosemide (Treatment) vs. lower dose (Control)
03.01 Failure to improve compliance
03.01.01 30 min after single dose
03.01.02 4 hours after single dose
03.02 Failure to improve resistance
03.02.01 30 min after single dose
03.02.02 4 hours after single dose
03.03 Failure to improve tidal volume
03.03.01 30 min after single dose
03.03.02 4 hours after single dose
03.04 Urinary calcium (mg/kg/day) over 24 hours
03.05 Calcium:creatinine ratio (mg:mg)
04 2 mg/kg aerosolized furosemide (Treatment) with 1 mg/kg (Control)
04.01 Change in compliance (ml/cm H2O/kg)
04.01.01 2 hours after single dose
04.01.02 4 hours after single dose
04.01.03 6 hours after single dose
04.02 Change in resistance (cm/L/sec)
04.02.01 2 hours after single dose
04.02.02 4 hours after single dose
04.02.03 6 hours after single dose
04.03 Change in tidal volume (ml/kg)
04.03.01 2 hours after single dose
04.03.02 4 hours after single dose
04.03.03 6 hours after single dose
Dr W Yong
Lecturer
Department of Pediatrics
Universiti Kebangsaan Malaysia
Jalan Yaacob Latif
Bandar Tun Razak
56000 Cheras
Kuala Lumpur MALAYSIA
E-mail: scyong888@yahoo.co.uk
| This review is published as a Cochrane review in The
Cochrane Library, Issue 3, 2006 (see http://www.thecochranelibrary.com for information). Cochrane reviews are regularly updated as new evidence
emerges and in response to feedback. The Cochrane Library should be
consulted for the most recent version of the review. |
