Ventilator-Associated Pneumonia

Introduction Definition 48 hours after intubation mechanically ventilated No clinical evidence of pneumonia prior to intubation Time of onset of pneumonia is important specific pathogens and outcomes Early-onset VAP (<4 days) better prognosis, antibioticsensitive Late-onset VAP (5 days or more) MDR pathogens increased patient mortality and morbidity. ATS/IDSA Guidelines: Guidelines for the management of adults with VAP

Pathogenic mechanisms

Diagnosis and Epidemiology Difficult Based on clinical indicators such as new or persistent infiltrates and purulent sputum Invasive bronchoscopic quantitative methods ( brush and bronchoalveolar lavage) : more precisely invasive, expensive, and may be less useful in patients with antibiotics quantitative cultures are not available in all hospitals.

ATS/IDSA Guidelines: Guidelines for the management of adults with VAP Evidence-based guideline Early, appropriate antibiotics in adequate doses Avoiding excessive antibiotics Based on microbiologic cultures, clinical response, shortening the duration to the minimum effective period.

Major epidemiologic points Polymicrobial; especially in ARDS (Level I) Aerobic G(-) bacilli (P. aeruginosa, K. P, and Acinetobacter species) G(+) cocci (S. aureus, much of which is MRSA) Anaerobes are an uncommon cause (Level II) Nosocomial virus and fungus are uncommon in immunocompetent patients. (Level I) MDR pathogens: severe, chronic underlying disease, late-onset varies by patient population, and type of ICU (Level II) ATS/IDSA Guidelines: Guidelines for the management of adults with VAP

Risk factors for VAP Duration of mechanical ventilation Aspiration of gastric contents COPD Use of PEEP Reintubation Duration of hosptalization Supine head positioning (head of bed not elevated) Fall or winter season Nasal intubation or sinusitis

Modifiable Risk Factors and Recommendation Intubation and mechanical ventilation Aspiration, body position and enteral feeding ATS/IDSA Guidelines: Guidelines for the management of adults with VAP

Modifiable Risk Factors and Recommendation Modulation of colonization: oral antiseptics and antibiotics Stress bleeding prophylaxis, transfusion and glucose control

Recommendations for the clinical strategy. Tracheal aspirate Gram stain can be direct initial therapy A negative tracheal aspirate has a strong value (94 %) progressive radiographic infiltrate + 2~3 clinical features represent the most accurate clinical criteria. Re-evaluation of using antibiotics based on the results of semi-quantitative, by Day 3 or sooner (Level II) ATS/IDSA Guidelines: Guidelines for the management of adults with VAP

Recommendations for initial antibiotic therapy Select an initial empiric therapy based on risk factors for MDR Local microbiology, cost, availability, and formulary restrictions For patients who have recently received an antibiotic→ a different antibiotic class ATS/IDSA Guidelines: Guidelines for the management of adults with VAP

Initial antibiotic therapy MDR risk factor

Initial antibiotic therapy

Recommendations for optimal antibiotic therapy Aerosolized antibiotics: not been proven (Level I) MDR with poor response : as adjunctive therapy (Level III) Combination therapy at initial Though no data compared with monotherapy aminoglycoside regimen, stopped after 5-7 days (Level III) If appropriate antibiotic, shorten the duration of therapy as 7 days (not P. aeruginosa !) (Level I).

Recommendations for selected MDR pathogens Combination therapy is recommended. Resistance ↑on monotherapy Appropriate and effective (Level II) Acinetobacter: carbapenems, sulbactam, colistin, polymyxin. ESBL+ Enterobacteriaceae: monotherapy of carbapenems (Level II) Adjunctive therapy ( inhaled aminoglycoside or polymyxin) for MDR G(-) (Level III) Linezolid is an alternative to vancomycin MRSA, renal insufficiency, nephrotoxic agents (Level III).

Ventilator Circuit Change and VAP UpToDate November 16, 2005

Ventilator circuit change Most important routes of bacterial invasion aspiration of oropharyngeal secretions inhalation of aerosols containing bacteria Common colonization of circuits with large numbers of microorganisms. Circuits were changed daily? 2~3 days? not a benign procedure, particularly for critically ill patients. Cost and time !!

Summary of Studies IntervalNumberResults Reference 8 hrs/24hrs 213/ ％ in both groups Am Rev Respir Dis 1978; 118: hrs/48 hrs 44/51No difference N Engl J Med 1982;306: hrs/48 hrs 106/ ％ / 14 ％ Am Rev Respir Dis 1991:143: hrs/ no change 35/28No significant difference Am Rev Respir Dis 1995;82: hrs/7 days 1708/1715No significant difference Anesthesiology 1995:82:903 7 days/no routine change 147/153No significant difference Ann Intern Med 1995:123:168 7 days/14 days 31/ /0163 Respir Care 1996;41:601

Recommendations Recommend that ventilator circuits can be changed at weekly Less frequent intervals without increasing the risk of VAP Required if gross soiling with blood or vomitus occurs The impact upon VAP is presently unclear for issues heated versus unheated circuits artificial noses versus heated humidifiers.

Summery

Summery MDR pathogens A lower respiratory tract culture needs to be collected Negative cultures: stop antibiotic therapy An empiric therapy regimen should include agents that are from a different antibiotic class than the patient has recently received.

Summery Combination therapy and short-duration (5 days) P. aeruginosa: aminoglycoside + ß-lactam Linezolid is an alternative to vancomycin, for proven MRSA. Aerosolized antibiotics to MDR pathogens. Ventilator circuits changed at weekly

References ATS/IDSA Guidelines: Guidelines for the management of adults with HAP, VAP, and HCAP American Thoracic Society, Am J Respir Crit Care Med 2005; 171:388. Ventilator circuit change and ventilator- associated pneumonia UpToDate November 16, 2005

Thanks for attention!