ABSTRACT
BACKGROUND AND AIMS: Our aim was to study the effects of a low-dose bolus (0.5 mcg/kg) of dexmedetomidine followed by two different infusion doses (0.25, 0.5 mcg/kg/h) on spinal anesthesia, sedation, hemodynamics and side effects. MATERIAL AND METHODS: Eighty consenting patients were randomized into two groups A and B with 40 patients each. Patients in both groups were administered intravenous (IV) dexmedetomidine 0.5 mcg/kg over 10 min prior to SAB followed by IV dexmedetomidine 0.25 mcg/kg/h infusion (A) and 0.5 mcg/kg/h infusion (B) throughout the duration of surgery. Time for onset of sensory and motor block, duration of motor block and analgesia, time for two segment regression, intra operative hemodynamics and sedation were assessed. P value less than 0.05 was taken as significant. RESULTS: Onset of sensory block to T10 was 2.1 ± 0.3 min in group A and group B. Onset of motor block was 4.6 ± 0.9 min in group A and 4.3 ± 0.9 min in group B. Duration of motor block in group A was 235.6 ± 12.4 min compared to group B which was 245.3 ± 9.3 min. Time for 2 segment regression in group A was 139.7 ± 29.7 min compared to group B which was 152.3 ± 18.7 min. Total duration of analgesia was 259.3 ± 92.4 min in group A and 273.8 ± 52.3 min in group B. There was a significant reduction in heart rate and mean blood pressure compared to the baseline within both the groups. Sedation was comparable in both the groups. CONCLUSION: IV dexmedetomidine bolus of 0.5 mcg/kg prior to subarachnoid block followed by maintenance infusion of 0.5 mcg/kg/h significantly prolonged duration of motor block, time for two segment regression, along with stable hemodynamics and adequate sedation.
ABSTRACT
BACKGROUND: The incidence of difficult intubation in patients undergoing general anaesthesia is estimated to be approximately 1-18% whereas that of failure to intubate is 0.05-0.35%.1,2,3 Various methods have been used for prediction of difficult laryngoscopy. Although, upper lip bite has been shown to be a promising test in its introductory article, repeated validation in various populations is required for any test to be accepted as a routine test. We have compared upper lip bite test (ULBT), modified Mallampati test (MMC) and thyromental distance (TMD) individually and in various combinations to verify which of these predictor tests are significantly associated with difficult glottic exposure. METHODS: After obtaining institutional ethics committee approval, 402 ASA I and II adult patients undergoing elective surgical procedures requiring endotracheal intubation were included. All the three test were performed in all the patients preoperatively and their glottic exposure was recorded by Cormack-Lehane classification during intubation. Sensitivity, specificity, positive predictive value and negative predictive value were used for comparison. RESULTS: In our study, the incidence of difficult laryngoscopy was 11.4% and failure to intubate 0.49%. None of the three are a suitable predictive test when used alone. Combination of tests added incremental diagnostic value. CONCLUSION: We conclude that all three screening tests for difficult intubation have only poor to moderate discriminative power when used alone. Combinations of individual tests add some incremental diagnostic value.
