Abstracts

Rationale: The occurrence of hypoxemia in adults with focal seizures with impairment of awareness (CP), primarily (1GTC) and secondarily (2GTC) generalized tonic-clonic seizures have been well-characterized.1,2  Many EMUs administer O2 via nasal cannula in the ictal or post-ictal states while some prefer not to administer O2 unless there is evidence of respiratory distress.  This study seeks to identify the ameliorating effects of ictal and post-ictal O2 via NC. Methods: Long-term video/EEG monitoring patients underwent monitoring of oxygen saturation using a digital SpO2 (pulse oximeter) transducer. We evaluated 103 consecutive seizures (65 CP, 13 1GTC, 25 2GTC) in 37 patients (20 male, 17 female). Results: Oxygen saturation data was available from 95 seizures (pulse oximeter malfunction in 8 seizures) equally distributed amongst seizure types, and 55 of these had O2 placed.  Of those having O2 placed, 34 had O2 placed during the course of the event (ictal O2) and 21 had place post-ictally (P-ictal O2).  The ictal O2 group exhibited an average O2 desaturation of 20+/-2.515% with recovery duration of 146.566 +/-44.757 sec. The P-ictal O2 group exhibited an average O2 desaturation of 16.1+/-1.842% with recovery duration of 113.235+/-17.236 sec. There was a significant difference in the duration of the clonic phase. The ictal O2 group demonstrated a longer clonic phase (60+/-5.57 sec) than P-ictal O2 group (35+/-2.42 sec)(p=0.0003). Analysis of any CP compared to any GTC produced statistically significant difference between the depth of O2 fall, with a decrease on average of 12.48+/-0.26% and 20.90+/-1.58% respectively (p=0.001). There was a trend for time from O2 administration to return of O2 saturation to baseline between any CP at 48+/-7.328 sec and any GTC at 199+/-78.322 sec (p=0.06). Conclusions: Our data shows that there was a significant difference in clonic duration when O2 is administered during the ictal state compared to the post-ictal state. GTC given O2 by nasal cannula showed a significantly larger depth of O2 desaturation related to CP on average. There was also a trend in the GTC group toward prolonged return of O2 saturation to baseline after O2 administration compared to the CP group. This would suggest the need for further investigation and analysis into the use of O2 by nasal cannula in EMU settings for this seizure population. Funding: None