A comparative study between intraoperativelow-dose ketamine and dexmedetomidine, as an anaesthetic adjuvant in lumbar spine instrumentation surgery for the post-operative analgesic requirement

Abstract

Background: Spinal instrumentation and fusion surgery presents the anaesthesiologist with multiple issues like intraoperative blood loss, hemodynamic changes, prolonged surgery etc, but the most probing aspect is analgesia. While both ketamine and dexmedetomidine as adjuvants have shown to decrease intraoperative anaesthetics and post operative analgesic consumption but there are no comparative studies. The primary aim of this study was comparison of post-operative analgesic requirements for 1st 24 hours after surgery when either of the drugs was used as adjuvants. Methods: Adult patients aged 18-60 years, of either sex, and ASA status I or II scheduled for elective lumbar spine instrumentation (of 2 or more spinal levels) surgery were enrolled for the study. Patients were randomised into one of the 3 treatment regimens ketamine/group K (0.5mg/kg bolus followed by 250 mcg/kg/h infusion), dexmedetomidine/ group D (0.5mcg/kg bolus followed by 0.5 mcg/kg/h infusion) or the placebo/ group S (saline/placebo). The study drugs were started after turning the patient prone. Data were recorded for intraoperative hemodynamics, anesthetic consumption (inhalational agent and opioids), emergence through RAS scale (Riker sedation agitation scale), PCA (patient controlled analgesia)-fentanyl use and VAS (visual analog scale) score in the 1st 24 hours after surgery. Appropriate statistical analysis was done. Results: A total of 42 patients (14 in each group) were enrolled. The total PCA fentanyl consumed in first 24 hours of surgery was maximum with the group-S (1366.6±382.6 mcg) in compared with group- D (1035.4±391.8 mcg) and group- K (1164.9±503.6 mcg) (P=0.13). The post extubation RAS score was lower in group-K (3.7±0.6) when compared with group-D (4±0.4) and group-S (4.5±0.9) (P=.009). Total intraoperative sevoflurane and fentanyl consumption showed no difference (P=0.19 and P=0.28). VAS score at rest was higher at baseline with group-S (P=0.009). The ICU stay was comparable (group-D: 1.4±0.5 d, group-K: 1.5±0.5 d, group-S: 1.9±0.5 d) among the groups. Hospital stay was also comparable (P=0.09). Conclusion: In patients undergoing lumbar instrumentation surgery, opioid consumption, VAS scores, PCA pump bad demands, inhalational agent consumption, hospital stay were comparable when either ketamine or dexmedetomidine was used as intraoperative anesthetic adjuvants.