Ventilatory status early after head injury.

The ventilatory status of patients within the first few hours following head injury has not been well established. We prospectively studied 63 patients who presented to an urban trauma center with varying severity of head injury to determine whether any trend toward hypo- or hyperventilation existed within the first two hours following injury. Arterial blood gas analysis done on emergency presentation showed that 14 patients with severe head injury (Glasgow coma scale less than or equal to 4) had mean pH values of 7.29 and mean PaCO2 of 41.86 torr. Twenty patients categorized as moderate head injury (GCS = 5-11) had mean pH values of 7.38 with a mean PaCO2 of 34.1 torr. Twenty-nine patients with GCS greater than or equal to 12 had mean pH and PaCO2 values of 7.4 and 31.8 torr, respectively. These differences in pH and PaCO2 were statistically significant between the GCS groups with mild and severe head injury (P less than or equal to .01 pH), (P = .05 PCO2), and could not be explained on the basis of hypoxemia, blood alcohol level, hypotension, or associated chest injury. It is concluded that patients with severe craniocerebral trauma show an early trend toward hypercapnea and acidosis. Immediate control of airway and assisted ventilation is necessary in order to reduce PaCO2 to optimal levels in patients with severe head injury.