A PIGLET MODEL OF STATUS EPILEPTICUS - COMPARISON OF CARDIORESPIRATORY AND METABOLIC CHANGES WITH 2 METHODS OF PENTYLENETETRAZOL ADMINISTRATION

Study objective: Impaired cardiac and respiratory responses during act ive toric-clonic convulsions (ictal periods) may contribute to complic ations during seizures. This study characterized physiologic parameter s in two pentylenetetrazol (PTZ)-induced seizure models. Participants: Twelve spontaneously breathing piglets. interventions- Under ketamine anesthesia, a tracheostomy was performed, and an arterial catheter an d epidural electrodes were inserted. Piglets received a PTZ bolus (100 mg/kg), with (six; 5 mg/kg/min) or without (six) an infusion of PTZ f or 20 minutes. Measurements and main results: Arterial blood gases, me an arterial pressure, heart rate, tidal volume, and EEG wave-forms wer e measured. Ictal periods had high-amplitude, synchronized EEG activit y; interictal periods had EEG suppression. Seizure duration (24 +/- 3. 5 versus 11 +/- 3.8 minutes; mean +/- SD) was significantly increased in the infusion group (P < .05). Significant increases in heart rate, minute ventilation, and base deficit plus decreases in pH occurred in both groups during seizures compared with baseline (P < .05). The dura tion and severity of metabolic acidosis were greater in the infusion g roup. During the first ten minutes of seizures, ten-second epochs were compared: beginning of ictal period, end of same ictal period, beginn ing of accompanying interictal period, and end of same interictal peri od. Respiratory rate decreased during initial interictal (65 +/- 40) m ore than latter ictal more than latter interictal period, compared wit h initial ictal period (194 +/- 65; P < .001). Tidal volume increased during latter ictal more than latter interictal more than initial icta l period (33 +/- 11), but the greatest increases occurred during initi al interictal period (140 +/- 55; P < .001). Conclusion: This model de monstrates significant increases in the duration and various measures of seizure severity in piglets given a PTZ infusion compared with thos e receiving a bolus alone. Systematic alterations in respiratory but n ot cardiac responses occur during ictal-interictal cycling of PTZ-indu ced seizures.