Each recommendation is rated based on the levels of the evidence and the grades of recommendation. Definitions of the grades of the recommendations (A, B, C, and D) and levels of the evidence (Level I- Level V) are presented at the end of the "Major Recommendations" field.
Recommendation #1: Ventilator circuits should not be changed routinely for infection control purposes. The available evidence suggests no patient harm and considerable cost savings associated with extended ventilator circuit change intervals. The maximum duration of time that circuits can be used safely is unknown. (Grade A)
Recommendation #2: Evidence is lacking related to ventilator-associated pneumonia (VAP) and issues of heated versus unheated circuits, type of heated humidifier, method for filling the humidifier, and technique for clearing condensate from the ventilator circuit. It is prudent to avoid excessive accumulation of condensate in the circuit. Care should be taken to avoid accidental drainage of condensate into the patient’s airway and to avoid contamination of caregivers during ventilator disconnection or during disposal of condensate. Care should be taken to avoid breaking the ventilator circuit, which could contaminate the interior of the circuit. (Grade D)
Recommendation #3: Although the available evidence suggests a lower VAP rate with passive humidification than with active humidification, other issues related to the use of passive humidifiers (resistance, dead space volume, airway occlusion risk) preclude a recommendation for the general use of these devices. The decision to use a passive humidifier should not be based solely on infection control considerations. (Grade A)
Recommendation #4: Passive humidifiers do not need to be changed daily for reasons of infection control or technical performance. They can be safely used for at least 48 hours, and with some patient populations some devices may be able to be used for up to 1 week. (Grade A)
Recommendation #5: The use of closed suction catheters should be considered part of a VAP prevention strategy. When closed suction catheters are used, they do not need to be changed daily for infection control purposes. The maximum duration of time that closed suction catheters can be used safely is unknown. (Grade A)
Recommendation #6: Clinicians (respiratory therapists, nurses, and physicians) caring for mechanically ventilated patients should be aware of risk factors for VAP (e.g., nebulizer therapy, manual ventilation, and patient transport). (Grade B)
Rating Scheme for the Strength of the Recommendation
Grade A: Scientific evidence provided by randomized, well-designed, well-conducted, controlled trials with statistically significant results that consistently support the guideline recommendation; supported by Level 1 or 2 evidence
Grade B: Scientific evidence provided by well-designed, well-conducted observational studies with statistically significant results that consistently support the guideline recommendation; supported by Level 3 or 4 evidence
Grade C: Scientific evidence from bench studies, animal studies, case studies; supported by Level 5 evidence
Grade D: Expert opinion provides the basis for the guideline recommendation, but scientific evidence either provided inconsistent results or was lacking.
Rating Scheme for the Level of Evidence
Level 1: Randomized, controlled trial with statistically significant results
Level 2: Randomized, controlled trial with significant threats to validity (e.g., small sample size, inappropriate blinding, weak methodology)
Level 3: Observational study with a concurrent control group
Level 4: Observational study with a historical control group
Level 5: Bench study, animal study, case series