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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. 1. Bassel Ericsoussi, MDPulmonary & Critical Care SpecialistTHE VENTILATOR CIRCUIT AND VENTILATOR-ASSOCIATED PNEUMONIA (VAP)
  2. 2. DEFINITION• Pneumonia that develops at least 48 hoursafter the initiation of mechanical ventilation
  3. 3. Which of the Following increases therisk of VAP?• Daily ventilator circuit changing• Nasal intubation• IPPV• Antacid or histamine type 2 antagonist forstress ulcer prophylaxis• All the above
  4. 4. THE VENTILATOR CIRCUIT APPEARSTO HAVE ONLY A SMALL EFFECT ONTHE DEVELOPMENT OF VAPThis contradicts the widely held belief that theventilator circuit is an important contributor tothe development of VAP
  5. 5. THE SOURCE OF CONTAMINATION• The patient contaminates the circuit, ratherthan the circuit contaminates the patient• The microorganisms that colonize theventilator circuit originate from the patient
  6. 6. FREQUENCY OF VENTILATOR CIRCUIT CHANGE• Changing the ventilator circuit more frequentlydoes not decrease the frequency of VAP, andmaybe harmful• An observational study of 637 mechanicallyventilated patients– Compared circuit changes every 2, 7, or 30 days– The incidence of VAP was significantly greater in thegroup who underwent circuit changes every two days
  7. 7. ASPIRATION VS INHALATION• Aspiration of contaminated secretions is thepredominant cause of nosocomialpneumonia, not inhalation of aerosolscontaining bacteria
  8. 8. GUIDELINES FOR VENTILATOR CIRCUIT CHANGING• The Centers for Disease Control andPrevention (CDC) recommend that ventilatorcircuits be changed no more often than every48 hours• The American Association for Respiratory Care(AARC) recommends that ventilator circuitsnot be changed routinely for infection controlpurposes
  9. 9. PASSIVE VERSUS ACTIVEHUMIDIFICATION• ET-tube bypasses the area of the respiratory tract thatwarm and humidify inspired gases• Active humidification– Humidifier in the ventilator circuit warms and humidifiesthe inspired gas• Passive humidification– Artificial nose traps the patients exhaled warm humidity• Both associated with similar rates of VAP, mortality andrespiratory complications (Airway occlusion andatelectasis)
  10. 10. PASSIVE ACTIVECheaperLess effective (airway occlusion)Higher resistance to flow (problematic in SBT)Higher dead space volumePASSIVE VERSUS ACTIVEHUMIDIFICATIONWhen frequent clogging is an issue, use of anactive humidifier instead of a passivehumidifier should be considered.
  11. 11. Heated ventilator circuit doesn’t reduced therisk of VAP…True of false??
  12. 12. 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 decreaseshumidification, which might put patients at riskfor airway occlusion
  13. 13. Daily change of suction catheters does notreduce the frequency of VAPTrue or False?
  14. 14. 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 passedthrough 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 changedroutinely– 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
  15. 15. Nebulizer may increase the risk of VAPTrue or False???
  16. 16. NEBULIZER VERSUS INHALER• Nebulizers frequently become contaminatedand might contribute to the development ofVAP– Observational study (adjusted odds ratio 1.87,95% CI 1.38-2.54)• Use of a metered-dose inhaler probablyeliminates this risk– Inhalers are not part of the ventilator circuit
  17. 17. BAG-VALVE RESUSCITATOR• Kept at the bedside of mechanically ventilatedpatients• Often contaminated• May contribute to the development of VAP
  18. 18. THE VENTILATOR CIRCUIT APPEARSTO HAVE ONLY A SMALL EFFECT ONTHE DEVELOPMENT OF VAPThis contradicts the widely held belief that theventilator circuit is an important contributor tothe development of VAP
  19. 19. INTERVENTIONS THAT DECREASES THEINCIDENCE OF VAP• Subglottic drainage• HOB elevation• Maintaining an endotracheal tube airway cuff pressure that isadequate to prevent aspiration of contaminated secretions• Silver coated endotracheal tubes• Avoiding the need for reintubation• Noninvasive instead of invasive mechanical ventilation wheneverpossible• Minimizing transport out of the ICU– Observational studies– Patients who are transported out of the ICU have an incidence of VAPthat is three to four times that of patients who are never transportedout of the ICU
  20. 20. The application of PEEP may decrease theincidence of VAPTrue or false???
  21. 21. • Randomized trial on 131 mechanicallyventilated• No PEEP: 25.4% VAP• 5 to 8 cm H2O of PEEP: 9.4% VAP• Relative risk 0.37, 95% CI 0.15-0.8THE APPLICATION OF PEEP MAYDECREASE THE INCIDENCE OF VAPThe positive tracheal pressure opposesaspiration of pharyngeal secretions around thecuff of the endotracheal tube
  22. 22. WEANING PROTOCOLS AND VAP• Weaning protocols are recommended toreduce the duration of ventilation• The shorter the duration on the ventilator thelower the risk of VAP– Observational study• No weaning protocol: 15% VAP• Weaning protocol: 5% VAP
  23. 23. SUMMARY AND RECOMMENDATIONS• The ventilator circuit appears to have only a small effect onthe development of VAP• We recommend AGAINST routine ventilator circuit changes• We recommend AGAINST using passive humidification, aheated ventilator circuit, or a closed suction system for thesole purpose of reducing the incidence of VAP• We suggest using metered-dose inhalers instead ofnebulizers to deliver aerosolized medications tomechanically ventilated patients
  24. 24. THANK YOU