Endotracheal tube suctioning is associated with a number of complications in newborn infants which have been well documented including hypoxaemia (Simbruner 1981, Danford 1983), bradycardia (Simbruner 1981, Cabal 1979), atelectasis (Fox 1978), mucosal trauma and pneumothorax (Anderson 1976, Vaughan 1978, Alpin 1984). Other reported potentially adverse effects include raised blood pressure (Perlmann 1983, Shah 1992), changes in cerebral blood volume (Perlmann 1983, Shah 1992, Skov 1992, Bucher 1993)and cerebral haemoglobin deoxygenation (Shah 1992, Skov 1992).
Endotracheal suctioning without disconnection from ventilator with the use of specially designed endotracheal tube adaptors may reduce the risk of complications by minimising the interference with ventilation during the procedure.
A priori sub-group analyses:
Gestational age (< 29 wks)
Acute vs chronic respiratory failure
With or without preoxygenation
With or without increased mechanical ventilation
Each author extracted data separately, then compared and resolved differences. Standard methods of Cochrane Neonatal Review Group were used to synthesise the data including the use of relative risk and weighted mean difference for data measured on a continuous scale.
Additional information was requested from the authors of trials (Spence 1992, Tan 1992, Mosca 1997) to clarify methodology and seek further data regarding outcomes. Additional information was obtained for two of these studies (Spence 1992, Mosca 1997).
Two of these studies were included in this review (Gunderson 1986, Mosca 1997). Participants in the included studies were similar. The birth weight (BW) range was 760-2700g. The gestational age (GA) range was 25-36 weeks. All infants were receiving mechanical ventilation for respiratory distress, and receiving routine endotracheal suctioning. The studies used similar techniques and methodology. A suction procedure employing a special adapter which permitted endotracheal suction without disconnection from the ventilator was used. Preoxygenation was not performed in either study. Cross-over design was employed in both included studies. In each study, each infant underwent three paired suctioning procedures. The data used in this review were averages of the three measurements for each condition, with or without disconnection.
The effects of the suctioning methods on heart rate and oxygenation status were recorded. However, due to differences in measurement or lack of data, most outcomes reported in this review relate to the findings of individual trials. Only two outcomes were able to be assessed using the combined data from both studies. These were percentage change in heart rate and heart rate decrease greater than 10%. Bradycardia (heart rate < 100 bpm) was reported in both included studies, although only the data from Mosca 1997 were able to be included in this review. Episodes of hypoxia were reported by Gunderson 1986 (TcPO2 < 50 mm Hg) and Mosca 1997 (SaO2 <90%). Gunderson 1986 also reported change in heart rate and TcPO2. Mosca 1997 also reported cerebral blood volume and intracellular cerebral oxygenation using Near-infrared spectroscopy.
(For further details of included studies as well as outcomes assessed see "Table of Included Studies")
A further five studies were identified but excluded. Four of these were excluded as neither random nor quasi-random allocation to suction method was used (Graff 1987, Cabal 1979, Zmora 1980, Spence 1992). These studies used a cross-over design with alternation of suction method but did not randomly or quasi-randomly allocate the initial treatment method. Tan 1992 was excluded due to insufficient data. This study was published in abstract form and further data have been requested.
Details of the studies not included in the review are provided for the purposes of discussion.
Cabal 1979 excluded (not randomised)
Eight preterm appropriate for gestational age (AGA) infants with severe
respiratory distress syndrome (RDS) requiring mechanical ventilation and
oxygenation were studied during episodes of routine endotracheal suctioning.
Participants were preterm infants with a gestational age 33 (±3)
weeks and birthweight 1555g (± 584) grams [(Mean (SD)]. Two suction
procedures were alternatively performed in each infant at approximately
4-hour intervals. In Procedure A, disconnection of the ventilator and preoxygenation
by manual intermittent positive pressure ventilation (IPPV) for 15-seconds,
followed by Procedure B where the infant was suctioned with a Novametrix
C/D Suction Adaptor without ventilatory disruption or preoxygenation. Both
procedures involved pre suction chest vibration and instillation of normal
saline into the endotracheal tube. One hundred and twenty eight suctioning
events were measured with each procedure and changes in heart rate (HR)
and arterial oxygenation saturation (SaO2) during suctioning were compared.
This study reported beneficial effects in terms of HR and SaO2 measures
associated with the use of a closed method of suction compared to an open
technique with preoxygenation.
Graff 1987 - excluded (not randomised)
Twenty infants requiring ventilatory assistance were studied during
two suction procedures. Participants were preterm infants with a birthweight
1647(±1105) grams and gestational age 31 (±3) weeks, and
age at study was 6 days (±6.1) days [(Mean (SD)]. Two suction procedures
were performed in each infant, while nursed in the supine position. The
first procedure involved preoxygenation with an increase in FiO2 of 0.2,
followed by ventilation with an Ambu bag, and suction. At conclusion of
the suctioning the FiO2 was decreased to the previous setting. The second
procedure (study group) involved the use of a device called a Neo-Cath
which allows the alternate delivery of 4 L/min of 100% oxygen and suction
during the suction procedure. Both procedures involved the instillation
of normal saline into the endotracheal tube prior to suctioning. Transcutaneous
oxygen and carbon dioxide, heart rate (HR) and blood pressure (BP), were
recorded 5 minutes before the study (baseline measure), at 30 seconds,
then every 1 minute until the infant returned to the baseline. The study
reported beneficial effects on oxygenation status with the use of a closed
method of suction without preoxygenation compared with preoxygenation used
with an open suction technique. No difference was shown between the groups
in heart rate and blood pressure measures.
Zmora 1980 - excluded (not randomised)
Thirteen infants (BW 900 to 4400 g, GA 27 to 40 wk) requiring mechanical
ventilation for RDS, pneumonia, perinatal asphyxia and gastro-intestinal
surgery were studied. Nineteen paired studies were performed. Each study
involved routine endotracheal suctioning with disconnection, followed by
suctioning via a side-hole adaptor without disconnection at the next scheduled
pulmonary toilet, usually one to two hours later. Continuous transcutaneous
oxygen, heart rate and airway pressure monitoring was performed.
Results: In all but two studies, the percent decrease in TcPO2 was
less when suction was performed without disconnection. The magnitude of
these differences was significantly less in 12 of 19 studies on all occasions
(p=<0.01). Bradycardia was less in 6 infants, no different in 11, and
worse in one infant with suction without disconnection. Mean airway pressure
remained higher when using the side-hole adaptor. The greater the decrease
in mean airway pressure, the more severe was the decline in TcPO2.
Tan 1992 - excluded (insufficient data)
Fifty-six intubated infants were randomised to tracheal suction with
or without disconnection from mechanical ventilation. The abstract reported
a reduction of desaturation and duration of desaturation associated with
tracheal suctioning without disconnection.
Spence 1992 - excluded (not randomised)
Twenty low birthweight infants( BW 944-2500 g, GA 27-37 weeks) receiving
mechanical ventilation for respiratory distress were studied using a cross-over
design comparing suction with and without disconnection (Novametrix). Preoxygenation
(increase in Fio2 by 0.05) was performed as part of the standard procedure
in both groups. Each infant underwent three paired episodes of ETT suction.
Heart rate, TcPo2 and blood pressure were recorded over the suctioning
procedure. The study reported no difference between the groups in measures
of oxygenation, heart rate and blood pressure.
There were no post-randomisation exclusions of infants in the included trials. In Gunderson 1986, one study (out of three planned studies for each infant) for one neonate was dropped from analysis as during this period the FiO2 dropped to below 0.3 (thus meeting exclusion criterion). However, data from the other two study periods of this neonate were included in the analysis. Outcomes were available for all infants enrolled in Mosca 1997.
Heart rate effects
Heart rate decrease >10%. Two trials assessed this outcome. Neither
trial found evidence of effect. However, the meta-analysis finds that fewer
infants experienced heart rate decreases >10% when suctioning was performed
without disconnection (RR 0.56, 95% CI 0.32, 0.99).
Percentage change in heart rate. Two trials assessed this outcome. Mosca 1997 found a smaller percentage decrease in heart rate when suctioning was performed without disconnection, whereas Gunderson 1986 found no evidence of effect. The meta-analysis supports a smaller percentage decrease in heart rate with suctioning without disconnection (WMD 11.53%, 95% CI 3.64, 19.43).
Bradycardia (HR <100 bpm). One trial reported this outcome (Mosca 1997). No evidence of effect was found (RR 0.25, 95% CI 0.03, 1.90).
Oxygen effects
Percentage change in TcP02. One trial assessed this outcome (Gunderson
1986). There was a smaller percentage decrease in TcP02 when suctioning
was performed without disconnection (mean difference 18.50%, 95% CI 8.11,
28.89). The percentage decrease in TcP02 when suctioning was performed
without disconnection was only 2.9%, versus 21.4% with disconnection.
Hypoxia (Sa02 <90%). One trial assessed this outcome (Mosca 1997). Fewer infants experienced episodes of hypoxia when suctioning was performed without disconnection (RR 0.30, 95% CI 0.11, 0.80).
TcP02 decrease >10%. One trial assessed this outcome (Gunderson 1986). When suctioning was performed without disconnection, there was a statistically significant reduction in the proportion of infants in whom TcP02 decreased by >10% (RR 0.36, 95% CI 0.17, 0.79).
Due to insufficient data no other prespecified outcomes were able to be assessed. Sub-group analyses by gestational age, acute vs chronic respiratory failure, with or without preoxygenation and with or without increased mechanical ventilation could not be conducted. Further data have been requested.
The results of this review suggest that endotracheal suctioning without disconnection using an endotracheal adaptor is beneficial in terms of reducing some immediate adverse effects. This technique produced less disturbance to the cardiorespiratory status as measured by decrease in oxygenation and heart rate. However, this review was unable to asses the clinical significance of the observed benefits.
There was insufficient data available to assess other clinically important outcomes which were identified a priori. For example, none of the identified studies reported outcomes such as endotracheal tube dislodgment, infection, or major morbidities such as intraventricular haemorrhage and pneumothorax. Long term outcomes cannot be assessed due to the cross-over methodology of the studies. A priori subgroup analyses (gestational age, acute vs chronic respiratory failure, with or without preoxygenation) to detect differential effects were also unable to be performed.
The infants included in these studies were similar to the current population of patients in neonatal intensive care units, although the majority of the patients studied were above 1000 grams birth weight. However, all the patients were receiving conventional mechanical ventilation. As there are now newer techniques available such as patient-triggered and high frequency ventilation, it would be inappropriate to extrapolate these findings to patients other than those receiving conventional mechanical ventilation.
Although the number of infants studied in this review is small, the benefits of suction without disconnection on immediate complications of suctioning is consistent with other reports with similar findings. These include the identified studies which were not included in this review (Cabal 1979, Zmora 1980, Tan 1992, Graff 1987, Spence 1992).
The role of preoxygenation with endotracheal suctioning is the primary
objective of another Cochrane Neonatal Review in preparation.
| Study | Methods | Participants | Interventions | Outcomes | Notes | Allocation concealment |
| Gunderson 1986 | Blinding of randomisation: yes
Blinding of intervention: no Complete follow-up:yes Blind outcome assessment:yes Crossover design, random allocation. |
11 newborns with RDS. GA range 29-33weeks , Birth weight range 840-2125 gm. Age at time of study 24 - 75 hours. Negative blood cultures. Fio2 > 0.3 and receiving mechanical ventilation (including CPAP), ETT > 3.0mm (internal diameter). | Experimental group: Endotracheal tube suction using end hole endotracheal tube adaptor(Isothermal 3165). Control group received ETT suction using disconnection from ventilator. Single operator technique. Studied at beginning and end of three separate 2 hour study periods. | Heart rate: number of occasions >10% decrease, percent change, episodes
of bradycardia (<100bpm).
TcPO2: episodes of >10% decrease, decrease to <50mmHg and percent change. |
Preoxygenation not performed. | A |
| Mosca 1997 | Blinding of allocation: No (quasi-random)
Blinding of intervention: no Complete follow-up: yes Blinded outcome assessment: can't tell Quasi-randomised crossover design. |
11 preterm infants receiving mechanical ventilation for RDS or BPD. Median GA 29 weeks (range 25-36), median BW 1170 gm (range 760-2700 gm). | Experimental group: Suction without disconnection using an adapter
(Trach care, Ballard).
Control group: ETT suction group with disconnection from the ventilator. Each infant underwent one suction by each method 60 minutes apart. This was repeated three times on the same day at intervals of several hours alternating the order in which the suction method was performed. |
Mean arterial blood pressure, cerebral blood volume, intracellular cerebral oxygenation, heart rate change, bradycardia (HR<100bpm), PCO2, arterial oxygen saturation | Preoxygenation not performed. Individual patient data provided by Dr. Mosca. | C |
| Study | Reason for exclusion |
| Cabal 1979 | Unable to verify random or quasi-random allocation. |
| Graff 1987 | Unable to verify random or quasi-random allocation. |
| Spence 1992 | Random or quasi-random allocation not used. |
| Tan 1992 | Insufficient data (abstract only) |
| Zmora 1980 | Unable to verify random or quasi-random allocation. |
Gunderson LP, McPhee AJ, Donovan EF. Partially ventilated endotracheal suction: use in newborns with respiratory distress syndrome. Am J Dis Child 1986;140:462-5.
Mosca 1997 {published data only}
Mosca F, Colnaghi M, Lattanzio M, Bray M, Pugliese S, Fumagalli M. Closed versus open endotracheal suctioning in preterm infants: effects on cerebral oxygenation and blood volume. Biol Neonate 1997;72:9-14.
Cabal L, Devaskar S, Siassi B et al. New endotracheal tube adaptor reducing cardiopulmonary effects of suctioning. Crit Care Med 1979;7:552-555.
Graff 1987 {published data only}
Grafff M, France J, Hiatt M, Hegyi T. Prevention of hypoxia and hyperoxia during endotracheal suctioning. Crit Care Med 1987;15:1133-1135.
Spence 1992 {published data only}
Spence K, Johnston L. Evaluation of endotracheal suction using a side-hole adaptor in mechanically ventilated low birth weight infants. Royal Alexandra Hospital for Children, Sydney, NSW, Australia. Unpublished paper 1992.
Tan 1992 {published data only}
Tan L, Torres B, Kanarek K, Blair C. Randomized comparison of closed tracheal suction with open tracheal suction: Effect on oxygen saturation, heart rate, blood pressure, TcPCO2, TcPO2, and motor response. Pediatr Res 1992;31:225A.
Zmora 1980 {published data only}
Zmora E, Merritt A. Use of side-hole endotracheal tube adapter for tracheal aspiration. Am J Dis Child 1980;134:250-254.
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Shah AR, Kurth CD, Gwiazdowski SG, Chance B, Delivoria-Papadopolus M. Fluctuations in cerebral oxygenation and blood volume during endotracheal suctioning in premature infants. J Pediatr 1992;120:769-774.
Simbruner G, Coradello H, Fodor M, Lubec G, Pollak A. Effect of tracheal suction on oxygenation, circulation and lung mechanics in newborn infants. Arch Dis Child 1981;56:506-510.
Skov L, Ryding I, Pryds O, Greisen G. Changes in cerebral oxygenation and cerebral blood volume during endotracheal suctioning in ventilated neonates. Acta Pediatr 1992;81:389-393.
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