Hospital-acquired Pneumonia and Ventilator-associated Pneumonia

Recent Advances in Epidemiology and Management

François Barbier; Antoine Andremont; Michel Wolff; Lila Bouadma


Curr Opin Pulm Med. 2013;19(3):216-228. 

In This Article

Current Clinical Epidemiology: The Burden of Hospital-acquired Pneumonia and Ventilator-associated Pneumonia

The incidence of HAP ranges from five to more than 20 cases per 1000 hospital admissions.[1,11] Outside the ICU, highest rates are observed in the elderly, immunocompromised hosts, surgical patients and those receiving enteral feeding through a nasogastric tube.[1] Almost one-third of HAPs are ICU-acquired, with VAP accounting for 90% of cases. Overall, VAP occurs in 9–40% of intubated patients and represents the most frequent ICU-acquired infection.[12,13,14] Recent surveys from large healthcare networks reported a pooled incidence density of VAP ranging from two to 16 episodes per 1000 ventilator-days.[14,15] The daily incidence of VAP peaks between day 5 and day 9 of mechanical ventilation, whereas the cumulative incidence appears as roughly proportional to mechanical ventilation duration.[13,16,17] The main other risk factors for VAP and corresponding preventive measures are exposed in Table 1 .[17–42] Patients with the acute respiratory distress syndrome (ARDS) are especially at risk, as a likely result of prolonged mechanical ventilation and heavy sedation requirement, with a cumulative incidence of ~40% after day 10.[13] Whether neuromuscular blockade agents use increases and head of bed elevation or prone positioning decreases the risk of VAP in ARDS patients has not been confirmed by recent studies.[13,31–43] Early tracheostomy (i.e. within the first 7 days of mechanical ventilation) in patients with predictable weaning difficulties does not appear as an independent predictor of VAP when compared with late tracheostomy or prolonged tracheal intubation.[22,44,45] Other potential risk factors have been recently suggested, such as etomidate use for tracheal intubation or energetic deficit during the early ICU course (at least for Staphylococcus aureus VAP),[46,47] whereas steroids (for trauma patients) or statin use could be protective.[48,49]

Nonventilator-associated HAPs dramatically increase both the hospital length of stay and the cost of care, and are associated with an overall mortality of 27–51%,[11,50,51] the poorer prognosis being reported in the elderly. Subsequent functional disability and accelerated cognitive impairment in aged patients surviving bacterial sepsis may increase the social burden of this nosocomial event.[52] The crude mortality of VAP ranges from 22 to 60%.[7,13,14,53] Although the prognostic weight of underlying conditions prevails in many cases, the occurrence of VAP is associated with a two-fold increase of the likelihood of in-ICU death, most notably for patients with inadequate empirical therapy.[3] The directly attributable mortality is 6–9%, but varies from 3 to 17% depending on patient subgroups.[4,5] In addition, survivors experience poorer outcome than ICU patients who do not develop VAP, with significantly longer durations of mechanical ventilation, ICU stay and hospitalization.[7] The absolute increase in hospitalization costs is estimated to be ~40 000 USD per episode.[7]