The effects of sevoflurane, isoflurane and desflurane on QT interval of the ECG

BACKGROUND AND OBJECTIVE

To determine if there is any significant difference between the effects of desflurane, isoflurane and sevoflurane on the QT interval, QT dispersion, heart rate corrected QT interval and QTc dispersion of the electrocardiogram.

METHODS

The study was conducted in a prospective, double blind and randomized manner in a teaching hospital. Ninety ASA I patients, aged 16-50 yr, undergoing general anaesthesia for noncardiac surgery were studied.

RESULTS

There was no significant change in QT intervals during the study in any group (P > 0.05). QT dispersion in the sevoflurane group 49+/-14 ms vs. 37+/-10 ms; in the desflurane group 55+/-16 and 62+/-21 ms vs. 35+/-14 ms and in the isoflurane group 54+/-26 and 59+/-24 ms vs. 42+/-19 ms were significantly increased at 3 and 10 min after 1 MAC of steady end-tidal anaesthetic concentration compared with baseline values (P < 0.05). QTc values in the sevoflurane group were 444+/-24 and 435+/-2 1ms vs. 413+/-19 ms (P < 0.05), in the isoflurane group were 450+/-26 and 455+/-34 ms vs. 416+/-34 ms (P < 0.05), in the desflurane group were 450+/-26 and 455+/-34 ms vs. 416+/-34 ms (P < 0.05) at 3 and 10 min after reaching 1 MAC of anaesthetic concentration and significantly increased compared with baseline values. QTc dispersion increased significantly with sevoflurane 62+/-14 ms vs. 45+/-16 ms (P < 0.05); isoflurane 70+/-36 ms at 3 min and 75+/-36 ms at 10 min after reaching 1 MAC of anaesthetic concentration vs. 50+/-24 ms (P < 0.05); desflurane 67+/-25 ms at 3 min and 74+/-27 ms at 10 min after 1 MAC concentration vs. 41+/-22 ms (P < 0.05).

CONCLUSION

Sevoflurane, isoflurane and desflurane all prolonged QTd, QTc and QTcd but there were no significant intergroup differences.

The effect of epidural anaesthesia and size of spinal needle on post-operative hearing loss

Forty-five patients who were to undergo elective urological operations were evaluated. In the pre-operative period and on the third or fourth post-operative day audiometry was performed. Epidural anaesthesia was performed in 15 cases, spinal anaesthesia was performed in 15 cases with 25 G needles, and in 15 cases with 22 G needles. No statistically significant hearing loss was observed in the post-operative period compared to preoperative period in the epidural anaesthesia group. In the post-operative period, the hearing loss observed in the 25 G-spinal anaesthesia group was significantly (P < 0.01) less than that seen in the 22 G group. None of the patients had headache after spinal anaesthesia. It was concluded that pure tone audiometry is a more sensitive indicator of cerebrospinal fluid leakage than post-operative headache.