Dose-dependent Rate of Nosocomial Pulmonary Infection in Mechanically Ventilated Patients with Brain Oedema Receiving Barbiturates: a Prospective Case Study

In a prospective case study we investigated whether the application of barbiturates in artificially ventilated patients with brain oedema has dose-dependent effects on the rate of nosocomial pneumonia. Pneumonia developed within the first seven days of controlled ventilation in patients receiving barbiturates; furthermore, the rate of nosocomial pneumonia was significantly higher in patients receiving barbiturates than in the control group without barbiturates (7.7%; p less than 0.0181); thus a clear dose dependency was shown (high-dose group: 43.8%, low-dose group: 21.4%). In all patients with pneumonia, colonization of the respiratory tract with pathogenic organisms preceded the pulmonary infection by four days. Under barbiturate therapy colonization of the respiratory tract occurred in all patients and one or two days earlier than in the control group, in which only 70% of the patients were colonized. These differences were significant for each of the first six days after hospitalization (p less than 0.0001-0.013). While in the high-dose group both colonization and pneumonia were caused mainly by gram-positive pathogens, mixed gram-positive and gram-negative pathogens were isolated in groups 2 and 3. Thus the higher rate of pneumonia of 43.8% in the high-dose group suggests a need for regular and semiquantitative monitoring of the causative agents and their antibiogram. Such measures could lead to early recognition with high predictability of the development of nosocomial pneumonia in colonized patients, allowing for timely application of the most appropriate antibiotics.