Hypoxemia following generalized convulsive seizures: Risk factors and effect of oxygen therapy

Abstract

Objective: To analyze the factors that determine the occurrence or severity of postictal hypoxemia in the immediate aftermath of a generalized convulsive seizure (GCS).

Methods: We reviewed the video-EEG recordings of 1,006 patients with drug-resistant focal epilepsy included in the REPO₂MSE study to identify those with ≥1 GCS and pulse oximetry (SpO₂) measurement. Factors determining recovery of SpO₂ ≥ 90% were investigated using Cox proportional hazards models. Association between SpO₂ nadir and person- or seizure-specific variables was analyzed after correction for individual effects and the varying number of seizures.

Results: A total of 107 GCS in 73 patients were analyzed. A transient hypoxemia was observed in 92 GCS (86%). Rate of GCS with SpO₂ <70% dropped from 40% to 21% when oxygen was administered early (p = 0.046). Early recovery of SpO₂ ≥90% was associated with early administration of oxygen (p = 0.004), absence of postictal generalized EEG suppression (PGES) (p = 0.014), and extratemporal lobe epilepsy (p = 0.001). Lack of early administration of O₂ (p = 0.003), occurrence of PGES (p = 0.018), and occurrence of ictal hypoxemia during the focal phase (p = 0.022) were associated with lower SpO₂ nadir.

Conclusion: Postictal hypoxemia was observed in the immediate aftermath of nearly all GCS but administration of oxygen had a strong preventive effect. Severity of postictal hypoxemia was greater in temporal lobe epilepsy and when hypoxemia was already observed before the onset of secondary GCS.