gms | German Medical Science

Objective: Surgery for posterior fossa lesions is often performed in a semisitting position which provides distinct advantages but which may be burdened also by serious side effects. In particular, supratentorial pneumocephalus which may lead to decreased alertness and other symptoms is a common problem. We here aimed to prove the efficacy of normobaric hyperoxia according to a standardized treatment protocol.

Method: We enrolled 44 patients with postoperative supratentorial pneumocephalus (>30 ml) after posterior fossa surgery in a semisitting position in this study. After randomisation procedure, patients received either normobaric hyperoxia at FiO₂ 100% over an endotracheal tube for 3 hours (treatment arm) or room air (control arm). Cranial CT scans were performed immediately (CT1) and 24 hours (CT2) after completion of surgery and were rated without knowledge of the therapy arm. Two co-primary endpoints were assessed: (i) mean change of pneumocephalus volume, and (ii) air resorption rate in 24 hour. Both primary endpoints were analysed using an analysis of covariance (ANCOVA) model incorporating the air volume at CT1. Secondary endpoints were subjective alertness (Stanford Sleepiness Scale) postoperatively and attention (Stroop test), which were evaluated preoperatively and 24 hours after surgery.

Results: Mean volume (± standard deviation) of pneumocephalus at baseline was 109.09 ± 59.46 ml in the treatment arm and 104.7 ± 62.66 ml in the control arm. Following treatment, the mean change in the volume of pneumocephalus adjusted for the volume at baseline was 87.83 ml in the treatment arm, while it was 71.29 ml in the control arm. The treatment effect in the respective ANCOVA model was statistically significant (p=0.001). The air resorption rate was significantly higher in patients in the treatment arm as compared to patients in the control arm (p=0.0015). No difference between treated and untreated patients was observed for the Stroop test. The distribution of scores in the Stanford Sleepiness Scale differed in the treatment arm as compared to the control arm, and there was a significant difference in mean values (p=0.015).

Conclusions: Administration of normobaric hyperoxia at FiO₂ 100% via an endotracheal tube for 3 hours is safe and efficacious in the treatment of pneumocephalus after posterior fossa surgery in the semisitting position.