Background: Pre-hospital endotracheal intubation for the purpose of controlled ventilation may prevent secondary brain injury in patients with severe head injury. In view of the limited monitoring devices utilized in the pre-hospital setting, little is known about the 'quality' of controlled ventilation initiated in the pre-hospital setting.
Methods: Included in this prospective study were 122 trauma patients with severe head injury (abbreviated injury scale score > or = 3). In all cases, the pre-hospital treatment included endotracheal intubation in the field. Upon hospital admission, and maintaining the same ventilation mode and setting initiated in the pre-hospital setting, arterial blood gas samples were taken.
Results: 'Optimal' oxygenation (PaO2 > 100 mm Hg) was achieved in 85.2% and 'adequate' ventilation (PaCO2 35-45 mm Hg) in 42.6% of the patients upon hospital admission. 'Optimal' oxygenation as well as 'adequate' ventilation was achieved in 37.7% of the study population. Hypoxaemia (PaO2 < 60 mm Hg) was observed in 2.5%, hypercapnia (PaCO2 > 45 mm Hg) in 16.4%, and hypocapnia (PaCO2 < 35 mm Hg) in 40.9% of the study patients. The incidence of hypocapnia was significantly more frequent in polytraumatized patients. Hypocapnia as well as hypercapnia was significantly more frequent in patients with associated pulmonary contusion.
Conclusions: Endotracheal intubation and controlled ventilation of the lungs initiated in the pre-hospital setting do not guarantee optimal oxygenaton and ventilation in patients with severe head injury.