CO-INDUCTION: A COMPARATIVE STUDY OF MIDAZOLAM KETAMINE AND PROPOFOL AS COINDUCING AGENTS TO PROPOFOL

INTRODUCTION: "Co-induction" refers to the administration of a small dose of a sedative or anaesthetic agent prior to the induction of anesthesia, with the aim of achieving more specific 'target' responses, while minimizing side effects. Although Propofol is a very popular IV induction agent, it causes various adverse effects like hypotension and apnoea and it is expensive. So the present study was designed to find whether the concept of co-induction can be used to overcome the above mentioned short comings of Propofol induction. AIM: To compare the effectiveness and evaluate the use of midazolam, ketamine and propofol as co-inducing agents to propofol for general anesthesia. DESIGN: A Prospective Randomized Double blind study was planned. METHODS: 100 adult patients of ASA grade 1 and 2 aged between 18-50 yrs. undergoing elective general, orthopedic or gynecological surgeries under general anesthesia were randomly allocated into four groups of 25 each: Group SP: received normal saline 3 ml IV as co-induction agent. Group MP: received inj. Midazolam 0.03mg\kg IV Group KP: received inj. Ketamine 0.3mg\kg IV. Group PP: received inj. Propofol 0.4mg\kg IV (auto-co-induction). All patients received inj. Pentazocine 0.3 mg\kg IV followed by blinded pretreatment with either saline 3ml IV, (group SP-control), inj. Midazolam. 0.03mg\kg IV (group M), Inj. Ketamine 0.3mg\kg IV (group KP) or inj. Propofol 0.4mg\kg IV (group PP). Two min later induction was done with inj Propofol until loss of verbal contact or resistance to placement of facemask. Total induction dose of Propofol, associated haemodynamic parameters (HR, MAP) at 1min interval for five min after induction and occurrence of significant apnoea (>20 sec or Spo2 < 90%) were recorded. The obtained data was analyzed using Chi-square test and Students "t" test. RESULTS & CONCLUSION: The mean induction dose of propofol was 1.31mg\kg, 1.39mg\kg, 1.59mg\kg in groups MP, KP, PP respectively as compared to 1.96mg\kg in control group (group SP). Midazolam was most effective in reducing the induction dose of propofol (33.16% compared to control). Total induction cost reduced by 22.2% & 14% in groups MP&KP respectively compared to control. The Propofol-Propofol Group PP (auto-co-induction) appeared to be the most expensive combination (1.65% increase in cost compared to control). Midazolam-Propofol appeared to be the most economical combination. When compared to control group - none of the three groups-viz Midazolam-Propofol, Ketamine-Propofol and Propofol-Propofol provided more haemodynamic stability during induction. In group Ketamine-Propofol, the HR and MAP were increased significantly (p<0.05 for HR and p<0.01 for MAP) compared with baseline values. Midazolam co-induction was associated with least incidence of Apnea during induction with Propofol compared to other groups.