Frequency and Etiology of Ventilator-Associated Events in the Medical Intensive Care Unit

The Centers for Disease Control and Prevention (CDC) has developed new criteria based on a significant deterioration in oxygenation to identify ventilator-associated events (conditions). The aim of this study was to determine how frequently this happened and what caused these conditions.

Electronic medical records and x-rays from 281 ventilator episodes in the medical intensive care unit were reviewed to determine the characteristics of patients requiring ventilation and the number of patients meeting the criteria for ventilator-associated conditions (VACs).

This cohort included 257 patients (55.4% men) who required 281 episodes of mechanical ventilation. The mean Acute Physiology and Chronic Healthy Evaluation II score was 13.5 ± 5.9. The initial mean PaO2/FiO2 was 210 ± 110. The median number of ventilator days was 4 (interquartile range: 3-9). The overall mortality was 32.3%. Nineteen patients (11.7% of eligible episodes) met the CDC criteria for a VAC; 6 met FiO2 criteria (31.6%) and 13 met positive end expiratory pressure criteria (68.4%). Twelve patients (63.2%) had an increased white blood cell count (>12k/μL) during the event. Eleven patients had an increase in temperature (>38°C) during this period. The etiology of these conditions included pneumonia (n = 4), atelectasis (n = 4), congestive heart failure (n = 5), acute respiratory distress syndrome (n = 2), and miscellaneous reasons (n = 4).

VACs occurred in 11.7% of patients in our medical intensive care unit. The etiology of these events was diverse and did not usually reflect complications. These new CDC criteria for institutional reporting of complications during mechanical ventilation do not necessarily identify complications or provide a good method for comparing outcomes in hospitals.