THE VENTILATOR CIRCUIT APPEARS TO HAVE ONLY A SMALL EFFECT ON THE DEVELOPMENT OF VAP. This contradicts the widely held belief that the ventilator circuit is an important contributor to the development of VAP

1. Bassel Ericsoussi, MD
Pulmonary & Critical Care Specialist
THE VENTILATOR CIRCUIT AND VENTILATOR-
ASSOCIATED PNEUMONIA (VAP)

2. DEFINITION
• Pneumonia that develops at least 48 hours
after the initiation of mechanical ventilation

3. Which of the Following increases the
risk of VAP?
• Daily ventilator circuit changing
• Nasal intubation
• IPPV
• Antacid or histamine type 2 antagonist for
stress ulcer prophylaxis
• All the above

6. THE VENTILATOR CIRCUIT APPEARS
TO HAVE ONLY A SMALL EFFECT ON
THE DEVELOPMENT OF VAP
This contradicts the widely held belief that the
ventilator circuit is an important contributor to
the development of VAP

7. THE SOURCE OF CONTAMINATION
• The patient contaminates the circuit, rather
than the circuit contaminates the patient
• The microorganisms that colonize the
ventilator circuit originate from the patient

8. FREQUENCY OF VENTILATOR CIRCUIT CHANGE
• Changing the ventilator circuit more frequently
does not decrease the frequency of VAP, and
maybe harmful
• An observational study of 637 mechanically
ventilated patients
– Compared circuit changes every 2, 7, or 30 days
– The incidence of VAP was significantly greater in the
group who underwent circuit changes every two days

9. ASPIRATION VS INHALATION
• Aspiration of contaminated secretions is the
predominant cause of nosocomial
pneumonia, not inhalation of aerosols
containing bacteria

10. GUIDELINES FOR VENTILATOR CIRCUIT CHANGING
• The Centers for Disease Control and
Prevention (CDC) recommend that ventilator
circuits be changed no more often than every
48 hours
• The American Association for Respiratory Care
(AARC) recommends that ventilator circuits
not be changed routinely for infection control
purposes

11. PASSIVE VERSUS ACTIVE
HUMIDIFICATION
• ET-tube bypasses the area of the respiratory tract that
warm and humidify inspired gases
• Active humidification
– Humidifier in the ventilator circuit warms and humidifies
the inspired gas
• Passive humidification
– Artificial nose traps the patient's exhaled warm humidity
• Both associated with similar rates of VAP, mortality and
respiratory complications (Airway occlusion and
atelectasis)

12. PASSIVE ACTIVE
Cheaper
Less effective (airway occlusion)
Higher resistance to flow (problematic in SBT)
Higher dead space volume
PASSIVE VERSUS ACTIVE
HUMIDIFICATION
When frequent clogging is an issue, use of an
active humidifier instead of a passive
humidifier should be considered.

13. Heated ventilator circuit doesn’t reduced the
risk of VAP…
True of false??

14. HEATED VERSUS UNHEATED CIRCUIT
• No difference in the incidence of VAP
– Randomized trial on 97 patients
• Heated circuit is preferred
– The risk of a heated circuit is that it decreases
humidification, which might put patients at risk
for airway occlusion

15. Daily change of suction catheters does not
reduce the frequency of VAP
True or False?

16. CLOSED VERSUS OPEN SUCTION
• No difference in the incidence of VAP
– Meta-analysis of 9 randomized trials (1292 patients)
• Closed suction
– The patient can be suctioned without being disconnected from the ventilator
• Open suction
– The patient is disconnected from the ventilator and then the suction catheter is passed
through the endotracheal tube
• Overall, closed suction system is preferred
– Prevent spraying tracheal secretions into the ICU during suctioning
– The suction catheters should be considered part of the ventilator circuit and not changed
routinely
– The maximum duration of time that closed suction catheters can be used safely is unknown
– Daily change of suction catheters does not reduce the frequency of
• Randomized trial on 521 mechanically ventilated patients
• Daily change vs. visible soiling

17. Nebulizer may increase the risk of VAP
True or False???

18. NEBULIZER VERSUS INHALER
• Nebulizers frequently become contaminated
and might contribute to the development of
VAP
– Observational study (adjusted odds ratio 1.87,
95% CI 1.38-2.54)
• Use of a metered-dose inhaler probably
eliminates this risk
– Inhalers are not part of the ventilator circuit

19. BAG-VALVE RESUSCITATOR
• Kept at the bedside of mechanically ventilated
patients
• Often contaminated
• May contribute to the development of VAP

20. THE VENTILATOR CIRCUIT APPEARS
TO HAVE ONLY A SMALL EFFECT ON
THE DEVELOPMENT OF VAP
This contradicts the widely held belief that the
ventilator circuit is an important contributor to
the development of VAP

21. INTERVENTIONS THAT DECREASES THE
INCIDENCE OF VAP
• Subglottic drainage
• HOB elevation
• Maintaining an endotracheal tube airway cuff pressure that is
adequate to prevent aspiration of contaminated secretions
• Silver coated endotracheal tubes
• Avoiding the need for reintubation
• Noninvasive instead of invasive mechanical ventilation whenever
possible
• Minimizing transport out of the ICU
– Observational studies
– Patients who are transported out of the ICU have an incidence of VAP
that is three to four times that of patients who are never transported
out of the ICU

22. The application of PEEP may decrease the
incidence of VAP
True or false???

23. • Randomized trial on 131 mechanically
ventilated
• No PEEP: 25.4% VAP
• 5 to 8 cm H2O of PEEP: 9.4% VAP
• Relative risk 0.37, 95% CI 0.15-0.8
THE APPLICATION OF PEEP MAY
DECREASE THE INCIDENCE OF VAP
The positive tracheal pressure opposes
aspiration of pharyngeal secretions around the
cuff of the endotracheal tube

24. WEANING PROTOCOLS AND VAP
• Weaning protocols are recommended to
reduce the duration of ventilation
• The shorter the duration on the ventilator the
lower the risk of VAP
– Observational study
• No weaning protocol: 15% VAP
• Weaning protocol: 5% VAP

25. SUMMARY AND RECOMMENDATIONS
• The ventilator circuit appears to have only a small effect on
the development of VAP
• We recommend AGAINST routine ventilator circuit changes
• We recommend AGAINST using passive humidification, a
heated ventilator circuit, or a closed suction system for the
sole purpose of reducing the incidence of VAP
• We suggest using metered-dose inhalers instead of
nebulizers to deliver aerosolized medications to
mechanically ventilated patients

26. THANK YOU