The Effect of Subanaesthetic Dose of Intrathecal Ketamine with Bupivacaine on Blood Pressure after Spinal Anaesthesia

Abstract

Background:
Spinal anaesthesia is commonly used in many surgeries especially caesarean section (CS). It is one of the most common complications of spinal anesthesia, and it is a challenge for anesthesiologists. It refers to low blood pressure after spinal anaesthesia hypotension, which may reach the point of shock that need rapid intervention to decrease peri-operative morbidity and mortality. A lot of techniques have been described to prevent such hypotension, but an effective method is yet to be found. Ketamine is one of the anaesthetic drugs that can be injected intrathecally due to its synergistic effect with the effects of local and analgesic anesthesia and has a sympathetic stimulating effect that can raise blood pressure.
Objectives:
The aim of the study is to evaluate the effect of using a sub-anesthetic dose of ketamine intrathecally on hypotension that follow spinal anaesthesia especially in CS delivery and other surgeries that receive spinal anaesthesia.
Methods:
This double-blinded randomized prospective study was conducted on 40 participation patients who were ASA 1 and 2, all the patients received spinal anesthesia. The patients were then randomly divided into two equal groups (n= 20 in each); ketamine group received a sub- anesthetic dose of ketamine of 0.5 mg/ kg intrathecal with local anaesthetic bupivacaine10 - 15 mg (2-3 ml 0.5%) and control (non ketamine) group received the same dose of local anaesthetics without ketamine. Mean arterial blood pressure (MAP) was recorded at baseline (5 minutes prior to the intrathecal injection), and at 5, 10, 15, 20 and 30 minutes after the injection. Incidences of hypotension and severe hypotension were recorded. The total doses of ephedrine and volume of infused fluid as cohydration were also recorded.
Results:
Compared to the control group, mild hypotension and severe hypotension were less frequent among the ketamine group. MAP was higher among ketamine group with statistical significance at 5 and 10 minutes. The number of cases who received ephedrine and the total ephedrine doses were significantly lower among the ketamine group. The volume of infused fluid and number of cases who received that volume were also significantly lower among the ketamine group.
Conclusion:
It is concluded that ketamine in a sub-anaesthetic dose intrathecally is an effective agent that can be used for alleviation of post-spinal anesthesia hypotension in patients undergoing spinal anaesthesia especially with CS delivery.