Incidence of awareness with explicit recall in patients undergoing general anaesthesia at Kenyatta National Hospital

Abstract

Background Awareness with explicit recall during anaesthesia, also known as intraoperative awareness, is a rare but debilitating complication of general anaesthesia. It can be anaesthesia related, surgical related, patient related or multifactorial. It has short term and long term consequences. These may include but are not limited to insomnia, panic attacks, sensation of pain and post traumatic stress disorder. It is mostly detected using a structured interview done over time. This is because memory tends to evolve over time. The most commonly used tool is a modified Brice questionnaire (table 1). Objectives Broad objective Determine the incidence, risk factors and groups at risk of awareness with recall (AWR) in patients undergoing general anaesthesia (GA) at Kenyatta National Hospital (KNH). Specific objective To determine the incidence of AWR in KNH To identify groups at risk of AWR at KNH To identify risk factors associated with AWR in KNH To come up with recommendations on minimizing AWR in KNH Methodology This was a prospective observational study on all patients over 18 years undergoing general anaesthesia at Kenyatta national hospital theatres. Evaluation of awareness was based upon three consecutive interviews. The patients were interviewed on the day of surgery (in PACU when fully awake) and then on the 3rd and 7th day post operatively. The interview was conducted using a modified Brice questionnaire (table 1). The interviewers were blinded to both the anaesthetic procedure and the medication used. Suspicion of an episode of AWR was registered together with its characteristics. Patient, anaesthetic and surgical characteristics and the drugs used perioperatively was recorded in a separate form by the person administering the anaesthesia. Results Data was obtained from a total of 369 patients undergoing general anaesthesia in KNH. The mean age of the patients was 38.8 (± 14.5) years with an age range between 18 and 82 years. Males were 186 (50.4%) and females 183 (49.6%) giving a male to female ratio of 1:1. Majority of patients were ASA I 230(63.5%). GA was administered by four anaesthesia provider cadres including consultants 108 (30.7%), graduate anaesthesia trainees 163 (46.3%), diploma anaesthesia trainees 32 (9.1%) and specialist anaesthesia registered clinical officers 49 (13.9%). Propofol 353(95.7%) and Fentanyl 319 (86.4%) were the most commonly used induction agents while maintenance was mostly done using Isoflurane 345 (93.5%) and nitrous oxide 272 (73.7%). The mean total gas flow 3.3 (SD ± 1.1) l/ min with a range between 1 and 7 l/ min. There were 6 (1.7%) patients with low total gas flow rates (≤ 1 l/min). The mean duration of anaesthesia and surgery were 2.7 (± 1.3) hrs and 2.4 (± 1.3) hours, respectively. Out of the 369 patients under GA, 2 had awareness with recall (AWR) giving a prevalence of 0.54%. The two patients with AWR were aged 23 years and 34 years, and both patients were male. There was no evidence of an association between patients age (p = 0.842) or sex (p = 0.16) and occurrence of AWR. Conclusion We were able to meet our primary objective which was incidence of AWR in patients undergoing GA at KNH. We got an incidence of 0.54% which is within the range (3). The two patients we got were both males and age range of 18-35 years. The statistical test done showed there was no association of gender and age with incidence of AWR. We were therefore unable to draw a conclusion on the risk factors and groups at risk of AWR. The study was not significantly powered to identify groups at risk and factors associated with AWR.