Prophylactic Low-Dose Ketamine to Prevent Post Anesthetic Shivering in Orthopedic Surgery: A Randomized-Controlled Study.

OBJECTIVE: Post anesthetic shivering is one of the most common anesthesia complications. We compared the efficacy of low-dose ketamine with normal saline in preventing post anesthetic shivering in orthopedic surgery. MATERIAL AND METHOD: The present study was a prospective, randomized, double-blind, controlled clinical trial involving 183 ASA I-II patients, aged 18 to 65 years whom underwent orthopedic surgery with general anesthesia. The patients were randomly allocated to receive either ketamine 0.25 mg/kg (Group K, n = 91) or normal saline (Group P n = 92) 20 minutes before the completion of surgery. The tympanic temperature was measured before the induction of anesthesia, 30 minutes after induction, and before administration of the study drugs. An investigator, blinded to the patients' group affiliation, graded post anesthetic shivering using the Crossley and Mahajan scale. The primary outcome was to compare incidence of shivering on each group in recovery room. The secondary outcome was side effect of ketamine. Statistical analyses were performed using program R version 3.1.0. A p-value of < 0.05 was considered statistically significant. RESULTS: The patient characteristics of the two groups were similar and the number of patients with observed shivering in both groups was not statistically significantly different (Group K = 13 (14.28%) and Group P = 15 (16.30%), p = 0.42). Furthermore, in both groups, no patient suffered from hallucination, and the other complications were not statistically different. CONCLUSION: At the recovery room, no significant efficacy difference between low-dose ketamine (0.25 mg/kg) and placebo in the prevention of post operative shivering in patients who underwent orthopedic surgery was observed. Other factors such as preload warm intravenous fluid, using active warming during surgery and control of the room temperature may help prevent shivering.

Perioperative desaturation and risk factors in general anesthesia.

OBJECTIVE: Despite advances in anesthetic technique, the incidence of perioperative desaturation in general anesthesia has remained high. Knowledge on factors associated with intraoperative desaturation is relatively scanty. The purpose of the present study was to investigate the distribution of time dependent intraoperative desaturation and factors predicting perioperative desaturation. MATERIAL AND METHOD: A prospective observational analytic study was conducted. One thousand and ninety three patients schedule for elective surgery under general anesthesia (GA) were enrolled. Exclusion criteria were patients with preoperative arterial oxygen saturation (SpO2) < or = 95%, pregnant women, obvious difficult airway and those requiring mechanical ventilation postoperatively. Desaturation was defined as oxygen saturation < or = 95% for > or = 10 seconds. RESULTS: Among 1093 eligible cases, 30 cases (2.74%) developed intraoperative desaturation. The probability of desaturation during induction, maintenance, and emergence were 0.55% (6/1093), 2.01% (22/1093), and 0.18% (2/1093), respectively. Occurrences of desaturation at the recovery room (RR) were noted in 224 patients (20.49%). Younger, obese patients, snorers, and lower respiratory tract infection were significant high-risk groups of intraoperative desaturation. Elderly, obese patients, snorers, positive history of pulmonary disease, modified Aldrete's score < or = 8, and duration of GA > or = 180 minutes predicted desaturation at RR. CONCLUSION: Obesity and snorers were the high-risk groups of perioperative desaturation. Elderly patients are at lower risk of desaturation than children intraoperatively, but at a higher risk in the postoperative period Higher FiO2 should be given to high-risk patients during the intraoperative period. Desaturation can still occur at RR, even in patients who received oxygen. Pulse oximeter monitoring should be continued throughout RR care.