RESUMO
BACKGROUND: Hyperventilation is recommended in electroconvulsive therapy (ECT) to enhance seizures and to increase patients' safety. However, more evidence is needed regarding its effects and the optimum method of application. METHODS: This prospective study involving 21 subjects compared two procedures, protocolized hyperventilation (PHV) and hyperventilation as usual (HVau), applied to the same patient in two consecutive sessions. Transcutaneous partial pressure of carbon dioxide (TcPCO2) was measured throughout all sessions. Ventilation parameters, hemodynamic measures, seizure characteristics, and side effects were also explored. RESULTS: PHV resulted in lower TcPCO2 after hyperventilation (p=.008) and over the whole session (p=.035). The lowest TcPCO2 was achieved after voluntary hyperventilation. Changes in TcPCO2 from baseline showed differences between HVau and PHV at each session time-point (all p<.05). Between- and within-subjects factors were statistically significant in a general linear model. Seizure duration was greater in PHV sessions (p=.028), without differences in other seizure quality parameters or adverse effects. Correlations were found between hypocapnia induction and seizure quality indexes. LIMITATIONS: Secondary outcomes could be underpowered. CONCLUSIONS: PHV produces hypocapnia before the stimulus, modifies patients' TcPCO2 values throughout the ECT session and lengthens seizure duration. Voluntary hyperventilation is the most important part of the PHV procedure with respect to achieving hypocapnia. A specific ventilation approach, CO2 quantification and monitoring may be advisable in ECT. PHV is easy to apply in daily clinical practice and does not imply added costs. Ventilation management has promising effects in terms of optimizing ECT technique.
