Ondansetron attenuates the decrease in blood pressure due to spinal anesthesia in the elderly: a double blind, placebo-controlled study.

BACKGROUND: Ondansetron was effectively used to prevent spinal anesthesia-induced hypotension in the general population and women anesthetised for cesarean section. The aim of this study was to test the hypothesis that blocking type 3 serotonin receptors with intravenous ondansetron administration reduces hypotension and bradycardia induced by spinal anesthesia in elderly patients. METHODS: Fifty-three patients participated in the study with 26 in the ondansetron group (received 8 mg intravenous ondansetron) and 27 in the placebo group (received 0.9% NaCl solution). The heart rate and arterial blood pressure were measured every 5 minutes after spinal anaesthesia, which was performed with 2.5 to 3 mL of 0.5% hyperbaric bupivacaine solution. RESULTS: Decreases in both the heart rate and mean systolic, as well as diastolic, arterial pressure compared to the baseline values were noted in both groups. The minimum diastolic and mean blood pressure values obtained over a 20-minute observation period were significantly higher in the ondansetron group. There were no significant differences in the systolic blood pressure and heart rate values between the groups. CONCLUSION: Administration of intravenous ondansetron prior to spinal anesthesia in geriatric patients attenuates the drop in the diastolic and mean arterial pressure without substantially affecting the systolic blood pressure.

Influence of promethazine on cardiac repolarisation: a double-blind, midazolam-controlled study.

Drugs used in anaesthesia may provoke torsadogenic changes in cardiac repolarisation. The aim of this study was to assess the effect of promethazine on the parameters of ventricular repolarisation: QTc interval and transmural dispersion of repolarisation. Forty patients were randomly allocated to receive promethazine (25 mg) or midazolam (2.5 mg). Changes in the ECG and arterial blood pressure were recorded. Correction of QT interval was calculated using Bazett's formula and Fridericia's correction; transmural dispersion of repolarisation was determined as T(peak)-T(end) time. Significant prolongation of QT interval, corrected with both formulae, was detected in patients receiving promethazine, while no change in the QTc value was observed in the midazolam group. There were no significant differences in T(peak)-T(end) time either between or within the groups. In conclusion, promethazine induces significant QTc prolongation but the lack of influence on transmural dispersion of repolarisation makes the risk of its torsadogenic action very low.

The effect of intravenous lidocaine on QT changes during tracheal intubation.

Laryngoscopy and tracheal intubation may provoke changes of cardiac repolarisation. The aim of this study was to assess the effect of intravenous lidocaine on the ECG changes induced by laryngoscopy and tracheal intubation. Forty-three female patients were randomly allocated to receive lidocaine (1.5 mg.kg(-1)) or placebo immediately after induction of anaesthesia and changes in the ECG and arterial blood pressure were recorded. Correction of QT interval was calculated using Bazett's formula (QTcb), Fridericia's correction (QTcf), and Framingham formula (QTcF). Transmural dispersion of repolarisation (TDR) was determined as Tpeak-Tend time. There were no changes in the QTc value in the lidocaine group. In the placebo group, significant increases in QTcb, QTcf and QTcF values were observed after intubation compared to either control measurements or to comparative measurements in the lidocaine group. There were no significant differences in TDR either between or within the groups. Lidocaine diminishes prolongation of QTc, induced by tracheal intubation but there is no effect of intubation on TDR.

Is prolongation of the QTc interval during isoflurane anaesthesia more prominent in women pretreated with anthracyclines for breast cancer?

BACKGROUND: Inhalation anaesthetics and anthracycline chemotherapeutic drugs may both prolong the QT interval of the electrocardiogram. We investigated whether isoflurane may induce or augment QTc prolongation in patients who had previously received cancer chemotherapy including anthracycline drugs. METHODS: Forty women undergoing surgery for breast cancer were included in the study. They were divided into two groups: (A) women previously treated with anthracyclines (n=20); and (B) women not treated with antineoplastic drugs (n=20). All patients received a standardized balanced anaesthetic in which isoflurane 0.5 vol% was used. The QT and corrected QT intervals were measured before anaesthesia, after induction and tracheal intubation, after 1, 5, 15, 30, 60 and 90 min of anaesthesia, and during recovery. RESULTS: In both groups we observed a tendency to QTc prolongation, but statistically significant differences among baseline values and values observed during isoflurane-containing anaesthesia were seen only in group A. During anaesthesia, significant differences in QTc values between the two groups were observed. CONCLUSION: In female patients pretreated with anthracyclines for breast cancer, the tendency to QTc prolongation during isoflurane-containing general anaesthesia was more strongly expressed than in patients without previous chemotherapy.