Monitoring hyperventilation in patients with closed head injury during air transport

Abstract

Introduction: We sought to determine the effectiveness of producing a therapeutic hypocapnic state with manual hyperventilation alone compared with manual hyperventilation plus end-tidal CO 2 monitoring in air transport of patients with closed head injury (CHI). Setting: Air medical (BK-117) transport of patients with CHI in the southeast Georgia/South Carolina region to a Level I trauma center. Methods: A retrospective control group of patients with CHI managed by unmonitored hyperventilation was compared with a prospective study group of patients with CHI with hyperventilation and end-tidal CO 2 monitoring. Adequate hyperventilation: Paco 2, 25 to 34 mm Hg. Results: Control group: 129 patients transported over a 6-year period met inclusion criteria. Study group: 18 of 44 patients transported over a 10-month period met criteria. For comparison analysis, arterial blood gas results were grouped into four categories: Paco 2 less than 25 mm Hg; 25 to 34 mm Hg; 35 to 40 mm Hg; greater than 40 mm Hg. Control group: 22% overventilated; 51% underventilated. Study group: 17% overventilated; none underventilated. Difference in nontherapeutic Paco 2 values between control group (73%) and study group (17%) was statistically significant ( p < 0.0001). Conclusion: Manual hyperventilation during transport of CHI patients did not maintain therapeutic hypocapnia. With end-tidal CO 2 monitoring, therapeutic hypocapnia was maintained in most patients. End-tidal CO 2 monitoring was effective in hyperventilating patients with CHI during air transport.