Does anesthetic induction for Cesarean section with a combination of ketamine and thiopentone confer any benefits over thiopentone or ketamine alone? A prospective randomized study.

BACKGROUND

The aim of this study was to evaluate the benefit of a combination of thiopentone and ketamine over either of these drugs alone as an induction agent for Cesarean section.

METHODS

Randomized prospective study of 3 groups of 20 patients (Group I: thiopentone alone; Group II: ketamine alone; Group III thiopentone and ketamine combination).

RESULTS

Systolic blood pressure (BP) (as measured at baseline, after induction, at intubation, and at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min): baseline BP did not differ significantly across groups. However, postinduction values were significantly higher for Group II (ketamine alone) (P>0.001), but these values normalized by 30 min postinduction. Diastolic BP (as measured at baseline, after induction, at intubation, and at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min): baseline BP did not differ significantly across groups. After induction, diastolic BP increased significantly in all groups. In Group I and Group III, these values returned to baseline after 10 min, and in Group II at the 30 min postinduction stage. Heart rate (measured at the same time as BP): at rest, presented no significant difference in heart rate across groups. At induction, all groups showed a significant rise in heart rate. At intubation, Group I showed an increase in heart rate, Group II a decrease in heart rate, and Group III no change. These intergroup variations were statistically significant. Apgar scores and umbilical venous gas measurements: although there were intergroup variations, these were not statistically significant. Postoperative pain assessment (subjective) VAS scores: the VAS pain scores 3 h after surgery were significantly higher in Group I, both at rest and coughing, at 24 h after surgery the difference persisted for scores at rest, but equalized during coughing. Postoperative pain assessment (objective) time to first analgesic demand: the duration of time to demand for first analgesic was significantly longer in Group II (ketamine only). Postoperative pain assessment (objective) total consumption of analgesic: patients of Group I consumed a significantly higher amount of analgesics than the other groups. Intraoperative event recall, awareness: no patient reported any adverse events of this nature.

CONCLUSIONS

We conclude that though there were no adverse events and a significantly lower analgesic requirement, the use of ketamine alone as an induction agent in Cesarean section should be avoided, as it causes significant maternal hemodynamic changes. The addition of a reduced dose of ketamine to thiopentone in the induction cocktail confers the benefit of reducing analgesic requirement without side effects. The treatment is safe and effective for the mother and child.