Descriptive Analysis of Postoperative Psychomimetic Side Effects of Subanesthetic Dose of Ketamine in Surgical Patients,HALA S. ABDEL-GHAFFAR
Abstract
Objectives: Most of clinical experience gained with the use of low dose ketamine focused in its analgesic efficacy. psychomimetic side effects of ketamine were reported as secondary outcome parameters and most of studies recorded event counts rather than severity. The aim of this study was the detailed analysis of postoperative psychomimetic side effects of subanesthetic dose of ketamine.
Methods: The study included 100 consented patients (aged 18-55 yrs), ASA I-II who were scheduled for different elective surgeries (including upper abdominal operations such as open cholecystectomy and epigastric hernia repair, thyroid, ear, nasal) under general anesthesia. Ketamine 0.9mg/kg iv bolus was administered intraoperatively before skin incision. Patients were strictly observed postoperatively for occurrence of ketamine psychomimetic side effects e.g. hallucination, eu-phoria, excitation, agitation, illusions whether visual or auditory, fear, slurred speech, nystagmus and photophobia. The onset (time since discontinuation of anesthesia till ap-pearance of side effect) and duration of each side effect were recorded.
Results: 45 patients were free from ketamine side effects. Not all side effects occurred in the same patient. 12 patients had one side effect, 25 patients had two side effects, 16 patients had 3 side effects, 2 patients had 4 side effects and no patient had more than 4 side effects. The observed ketamine side effects included nystagmus (n=29), Photophobia (n=35), slurred speech (n=24), euphoria (n=3), agitation (n=2), and hallucination (n=20). Their mean onset and duration times were: nystagmus (20.55±6.9 and 4.79±2.26 min.), photophobia (39.71±8.89 and 31.03±12.57 min.), slurred speech (72.2±9.49 and 89.78±14.84min.), euphoria (57.0±4.24 and 105.00± 21.21min.), agitation (55.6±2.5 and treated with 3mg mida-zolam), and hallucination (70.85±10.52 and 118.45± 36.18min.). A highly significant association was recorded between the incidence and severity of recorded psychomimetic side effects of ketamine and older age, female gender, upper abdominal operations and longer surgical times.
Conclusion: Since neuropsychiatric disturbances remain an issue with the use of ketamine, one must weigh the risks and benefits of this intervention. Outcomes other than pain and analgesic use (e.g. Adverse effects, duration of hospital stay and cost-benefit analysis) should be included in future research on ketamine whenever possible.