Ventilator-associated pneumonia

Template:Ventilator-associated pneumonia Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.D. [2]

Natural History, Complications and Prognosis

Prognosis predictor scores: CURB-65 | Pneumonia severity index | Criteria for severe community acquired pneumonia

Diagnosis

Diagnostic criteria | History and Symptoms | Physical Examination | Laboratory Findings | Chest X Ray

Treatment

Site of care decision | Medical Therapy | Other treatments consideration | Prevention | Management of non-responding pneumonia

Treatment

Treatment of VAP should be matched to known causative bacteria. However, when VAP is first suspected, the bacteria causing infection is typically not known and broad-spectrum antibiotics are given (empiric therapy) until the particular bacterium and its sensitivities are determined. Empiric antibiotics should take into account both the risk factors a particular individual has for resistant bacteria as well as the local prevalence of resistant microorganisms. If a person has previously had episodes of pneumonia, information may be available about prior causative bacteria. The choice of initial therapy is therefore entirely dependent on knowledge of local flora and will vary from hospital to hospital.

Risk factors for infection with an MDR strain include ventilation for more than five days, recent hospitalization (last 90 days), residence in a nursing home, treatment in a hemodialysis clinic, and prior antibiotic use (last 90 days).

Possible empirical therapy combinations include (but are not limited to):

• vancomycin/linezolid and ciprofloxacin,
• cefepime and gentamicin/amikacin/tobramycin
• vancomycin/linezolid and ceftazidime
• Ureidopenicillin plus β-lactamase inhibitor such as piperacillin/tazobactam or ticarcillin/clavulanate
• a carbapenem (e.g., imipenem or meropenem)

Therapy is typically changed once the causative bacteria are known and continued until symptoms resolve (often 7 to 14 days).

People who do not have risk factors for MDR organisms may be treated differently depending on local knowledge of prevalent bacteria. Appropriate antibiotics may include ceftriaxone, ciprofloxacin, levofloxacin, or ampicillin/sulbactam.

As of 2005, there is ongoing research into inhaled antibiotics as an adjunct to conventional therapy. Tobramycin and polymyxin B are commonly used in certain centres but there is no clinical evidence to support their use.

Prevention

Prevention of VAP involves limiting exposure to resistant bacteria, discontinuing mechanical ventilation as soon as possible, and a variety of strategies to limit infection while intubated. Resistant bacteria are spread in much the same ways as any communicable disease. Proper hand washing, sterile technique for invasive procedures, and isolation of individuals with known resistant organisms are all mandatory for effective infection control. A variety of aggressive weaning protocols to limit the amount of time a person spends intubation have been proposed. One important aspect is limiting the amount of sedation that a ventilated person receives.

Other recommendations for preventing VAP include raising the head of the bed to at least 45 degrees and placement of feedings tubes beyond the pylorus of the stomach. Antiseptic mouth washes such as chlorhexidine may also reduce the incidence of VAP. One study also suggests that using heat and moisture exchangers instead of heated humidifiers, may also reduce the incidence of VAP.

Epidemiology and prognosis

VAP occurs in up to 25% of all people who require mechanical ventilation. VAP can develop at any time during ventilation, but occurs more often in the first few days after intubation. This is because the intubation process itself contributes to the development of VAP. VAP occurring early after intubation typically involves fewer resistant organisms and is thus associated with a more favorable outcome. Because respiratory failure requiring mechanical ventilation is itself associated with a high mortality, determination of the exact contribution of VAP to mortality has been difficult. As of 2006, estimates range from 33% to 50% death in patients who develop VAP. Mortality is more likely when VAP is associated with certain microorganisms (Pseudomonas, Acinetobacter), blood stream infections, and ineffective initial antibiotics. VAP is especially common in people who have acute respiratory distress syndrome (ARDS).

See also

• Pneumonia
• Nosocomial infection

References

• American Thoracic Society and the Infectious Diseases Society of America. (2005). "ATS/IDSA Guidelines: Guidelines for the management of adults with HAP, VAP, and HCAP". Am J Respir Crit Care Med. 171: 388.

Template:WS