Postextubation pneumonia cases outnumbered ventilator-associated pneumonia cases among patients who underwent elective surgery under general anesthesia at a Japanese university hospital, according to a retrospective study published in Scientific Reports.
Researchers reviewed diagnosis procedure combination and administrative claims data from 31,828 patients who underwent elective surgery under general anesthesia at Hiroshima University Hospital from April 2016 to March 2023. The cohort was drawn from 35,535 general anesthesia cases after excluding patients who arrived by ambulance, underwent emergency surgery, or lacked body mass index or activities of daily living data at admission.
Postextubation pneumonia was defined as a new pneumonia diagnosis within 30 days following extubation with newly initiated antibiotic therapy on or after the diagnosis date. Ventilator-associated pneumonia was defined as pneumonia occurring at least 48 hours after initiation of mechanical ventilation while the patient remained on ventilatory support. Pneumonia diagnosed on the same day as extubation was classified as ventilator-associated pneumonia; when postextubation pneumonia and ventilator-associated pneumonia definitions overlapped, cases were classified as ventilator-associated pneumonia.
Among the included patients, 212 developed postextubation pneumonia, compared with 27 cases of ventilator-associated pneumonia. The incidence of postextubation pneumonia was 0.67%, which the researchers noted was lower than previously reported estimates in critically ill populations. They suggested the lower rate may reflect lower illness severity, shorter mechanical ventilation, and greater physiologic stability among elective surgical patients. However, they noted that even a low incidence may create a substantial clinical burden in high-volume surgical settings.
Most postextubation pneumonia cases occurred early: 80% developed within 1 week following extubation, and 93% developed within 2 weeks.
In multivariable analysis, older age, male sex, body mass index below 18.5, reduced Barthel Index scores, and consciousness disturbance at the level of spontaneous eye opening were independently associated with postextubation pneumonia. More severe consciousness disturbance, defined as inability to open the eyes spontaneously, was not independently associated with the outcome. The researchers did not identify a mechanism for the sex-based association.
Several surgical sites also were associated with postextubation pneumonia, although the magnitude of association varied. Gastrointestinal and cervical procedures were each associated with about four times the odds of postextubation pneumonia, while breast and facial procedures were associated with more than three-and-a-half times the odds. Neurosurgical procedures were associated with more than twice the odds, and respiratory and cardiovascular procedures were associated with more modestly increased odds. The researchers noted that surgical-site variables were treated as nonmutually exclusive indicators, meaning some patients may have had procedures involving more than one anatomical region. Smoking index was not independently associated with postextubation pneumonia after adjustment.
The researchers wrote that postextubation pneumonia differs mechanistically from ventilator-associated pneumonia because it develops following extubation and is thought to be driven primarily by swallowing dysfunction and impaired airway protection rather than infection during ongoing mechanical ventilation. They noted that postextubation pneumonia remains underrecognized as a distinct clinical entity and may require prevention strategies different from ventilator-associated pneumonia bundles, including dysphagia screening, oral care, posture and dietary modification, swallowing rehabilitation, and multidisciplinary management.
The study was limited by its retrospective, single-center design and reliance on claims-based pneumonia diagnoses. Swallowing function was not directly assessed, and data on nasogastric tube use, tracheostomy, vocal cord paralysis, ventilator settings, positive end-expiratory pressure levels, extubation techniques, and secretion management were incomplete or unavailable. The findings also may not be generalizable to emergency surgery, emergency intubation, intensive care unit populations, or settings outside Japan.
The researchers selected variables for the multivariable model a priori based on clinical relevance and existing literature, and they reported no evidence of substantial multicollinearity among covariates.
The researchers concluded that standardized definitions and targeted prevention strategies are needed for postextubation pneumonia, which remains underrecognized as a distinct clinical entity.
The authors declared no competing interests.
Source: Scientific Reports