Comparing intravenous dexmedetomidine and clonidine in hemodynamic changes and block following spinal anesthesia with ropivacaine in lower limb orthopedic surgery: a randomized clinical trial.

Dexmedetomidine (DEX) can prolong duration of anesthesia and shorten onset of sensory and motor block relative to clonidine. This study attempted to compare the efficacy of intravenous DEX and clonidine for hemodynamic changes and block after spinal anesthesia with ropivacaine in lower limb orthopedic surgery. In a double-blind randomized clinical trial, 120 patients undergoing spinal anesthesia in lower limb orthopedic surgery were recruited and divided into three groups using balanced block randomization: DEX group (n = 40; intravenous DEX 0.2 µg/kg), clonidine group (n = 40; intravenous clonidine 0.4 µg/kg), and placebo group (n = 40; intravenous normal saline 10 mL) in which pain scores were assessed using visual analogue scales (at recovery, and 2, 4, 6, and 12 hours after surgery) and time to achieve and onset of sensory and motor block. Statistically significant differences were found in mean arterial pressure among the groups at all times except baseline (P = 0.001), with a less mean arterial pressure and a prolonged duration of sensory and motor block (P = 0.001) in the DEX group where pain relieved in patients immediately after surgery and at above mentioned time points (P = 0.001). Simultaneous administration of intravenous DEX with ropivacaine for spinal anesthesia prolongs the duration of sensory and motor block and relieves postoperative pain, and however, can decrease blood pressure. Although intravenous DEX as an adjuvant can be helpful during spinal anesthesia with ropivacaine, it should be taken with caution owing to a lowering of mean arterial pressure in patients especially in the older adults. This study was approved by Ethical Committee of Arak University of Medical Sciences (No. IR.Arakmu.Rec.1395.450) in March, 2017, and the trial was registered and approved by the Iranian Registry of Clinical Trials (IRCT No. IRCT2017092020258N60) in 2017.

Effect of intravenous clonidine premedication for the bloodless surgical field in patients undergoing middle ear or nasal surgery: A comparison of three different doses.

AIM: To evaluate the effect of intravenous (IV) clonidine premedication for the bloodless surgical field in patients undergoing middle ear or nasal surgery comparing three different doses. SUBJECTS AND METHODS: This prospective randomized, clinical trial was performed on 90 normotensive patients belonging to American Society of Anesthesiologists grade I/II, aged 18-60 years, of either sex, undergoing routine middle ear or nasal surgery. These patients were divided into three Groups A, B, and C with 30 patients in each according to the dose of IV clonidine used as premedicant that is 3, 4, and 5 µg/kg, respectively. The hypotensive period commenced 10 min after the start of surgery till the surgeon's request for no hypotension required any longer. The target mean blood pressure for producing bloodless surgical field was 60-70 mmHg. During the hypotensive period, the surgeons were asked to rate the bleeding severity score on a six-point scale from 0 (no bleeding) to 5 (severe bleeding). STATISTICAL ANALYSIS USED: ANOVA, Chi-square test, Z-test, standard deviation and P value. RESULTS: IV clonidine premedication in a dose of 4 and 5 µg/kg reduces bleeding and provides a clear field for surgery. It also reduces the requirement of isoflurane, fentanyl, and metoprolol for controlled hypotension. However, clonidine 5 µg/kg was not more effective than clonidine 4 µg/kg in producing these effects rather was associated with some side effects. CONCLUSION: IV clonidine premedication in a dose of 4 µg/kg is safe and effective for producing a bloodless surgical field in the middle ear and nasal surgery.

Effects of Intra-Operative Intravenous Clonidine on Cardiovascular Responses to Extubation / 대한마취과학회지

Increases in heart rate (HR) and blood pressure (BP) are common during light planes of anesthesia at the end of operation and just prior to extubation. This study was undertaken to investigate and compare HR and BP responses to endotracheal extubation during light general anesthesia with and without prior intravenous administration of clonidine. Eighty hypertensive patients aged 45-65 yr were undergoing a variety of operations. In this study, the BP of hypertensive patients was well controlled on antihypertensive regimens before anesthesia. Anesthesia was induced by the injection of thiopental sodium, diazepam, fentanyl and vecuronium, and maintained with enflurane (0.8-2.5 per cent) and nitrous oxide (50 per cent) in oxygen. Patients were randomly divided into two groups of 40 each with regard to management of endotracheal extubation at the end of operation. Patients in clonidine group received an izv injection of clonidine (0.75 ug/kg) 30 min. prior to extubation. One minute prior to extubation, baseline arterial BP and HR were recoreded. Single measurement of systolic and diastolic BP and HR were obtained during the study and were recorded at 30 seconds, 1 min., 2 min., 3 min., 4 min. and 5 min. after extubation, and upon entrance to the postanesthetic recovery room (6-10 min. after extubation). Patients in control group received no injection prior to extubation, but were otherwise treated similarly and had data recorded at the same times as those in clonidine group. The results were as follows ;1) No significant differences were noted in BP and HR prior to clonidine administration between patients in the two groups. 2) Thirty seconds after extubation, both BP and HR increased significantly in both group (p< 0.05) but the increasing rate in clonidine group was significantly less than in control group (p<0.05). 3) Patients in control and clonidine group sustained a significant elevation in both BP and HR which persisted for 3 and 1 min after extubation (p<0.05), respectively. 4) Changes in both BP and HR in patients of clonidine group became significantly less than control group every time intervals after extubation (p<0.05). In conclusion, the result of this study demonstrate that iv injection of clonidine (0.75 ug/kg) administered 30 min. before endotracheal extubation prevents increases in BP and HR before and after extubation and in the recovery room. The data suggest that iv clonidine injection prior to extubation should be of advantage to patients with hypertension who may not be able to tolerate the increased hemodynamics which usually accompany endotracheal extubation.