A STUDY OF INCIDENCE OF AWARENESS IN GENERAL ANESTHESIA WITH INHALATIONAL AGENT (HALOTHANE)

BACKGROUND AND OBJECTIVES: Awareness during general anesthesia is a frightening experience, which may result in serious emotional injury and post-traumatic disorders. Awareness have been reported with many anesthetic techniques, particularly surgical patient populations such as those requiring anesthesia for Obstetrics, Major trauma, and cardiac surgery are known to experience a high incidence (7-43%) of awareness. In our study we have made an attempt to evaluate the incidence of awareness in surgical patients under general anesthesia using inhalational agent (Halothane) with Nitrous oxide. In this study we have evaluated the incidence of awareness by using Blood Pressure, Heart Rate, Sweating, Tears score intraoperatively and interviewing patients postoperatively by standard questionnaire. MATERIALS AND METHODS: Hundred patients undergoing surgical procedures under general Anesthesia were randomly selected for the study. They were posted to undergo surgery from November 2011 to July 2013. Parameters observed: Intraoperatively Blood Pressure, Heart Rate, Sweating, Tears scoring was done at 0 minutes in the operation theatre before induction and 10 minutes after intubation and monitored every 10 minutes till the end of surgery. All the patients were interviewed in the post-operative period soon after complete recovery and 24 hours later again with a set of 10 questions (Questionnaire method). RESULTS: In our study we have a standard interview questionnaire in the post operative period to study the incidence of awareness. We found that none of the patients had conscious recall of the events during surgery. In our study of 100 patients none of the patients had awareness. Injection atropine 20 mcg/ kg body weight and injection pethidine 1mg/ kg body weight were given as premedication. Induction agent used was injection thiopental sodium 5mg/ kg body weight and maintained with Nitrous oxide, Halothane as inhalational agent and muscle relaxation was achieved with injection pancuronium 0.1mg/ kg body weight. There was an increase in blood pressure and heart rate > 30 mm of hg or 30 beats/ min greater than the base line respectively (score 2 on Blood Pressure, Heart Rate, Sweating, Tears score), were seen in 5 seconds. However there were no abnormalities seen in three records and the heart rate were in normal range (score 0 or 1 Blood Pressure, Heart Rate, Sweating, Tears score). With regards to more objective parameters in the anesthetic records, increase in blood pressure (> 30 mm of hg) and heart rate (. 30 beats/ min) were observed in 67% of the awareness cases and 21% in matched controls. (p= 0.001). The concentration of halothane was increased from 0.2% to 0.6% in one patient who had both sweating and tears and with a sweating score of 2 in PRST scoring. 2 patients had tears and 1 patient had sweating and none of the patients had awareness. In our study patients who had anxious mental status pre-operatively showed exaggerated blood pressure intraoperatively.