The effect on post-operative pain of intravenous clonidine given before induction of anaesthesia

Intraoperative clonidine in endometriosis and spine surgery: A protocol for two randomised, blinded, placebo-controlled trials

BACKGROUND

A high proportion of patients who undergo surgery continue to suffer from moderate to severe pain in the early postoperative period despite advances in pain management strategies. Previous studies suggest that clonidine, an alpha2 adrenergic agonist, administered during the perioperative period could reduce acute postoperative pain intensity and opioid consumption. However, these studies have several limitations related to study design and sample size and hence, further studies are needed.

AIM

To investigate the effect of a single intravenous (IV) dose of intraoperative clonidine on postoperative opioid consumption, pain intensity, nausea, vomiting and sedation after endometriosis and spine surgery.

METHODS

Two separate randomised, blinded, placebo-controlled trials are planned. Patients scheduled for endometriosis (CLONIPAIN) will be randomised to receive either 150 μg intraoperative IV clonidine or placebo (isotonic saline). Patients undergoing spine surgery (CLONISPINE) will receive 3 μg/kg intraoperative IV clonidine or placebo. We aim to include 120 patients in each trial to achieve power of 90% at an alpha level of 0.05.

OUTCOMES

The primary outcome is opioid consumption within the first three postoperative hours. Secondary outcomes include pain intensity at rest and during coughing, nausea, vomiting and sedation within the first two postoperative hours and opioid consumption within the first six postoperative hours. Time to discharge from the PACU will be registered.

CONCLUSION

This study is expected to provide valuable information on the efficacy of intraoperative clonidine in acute postoperative pain management in patients undergoing endometriosis and spine surgery.

Comparison between intravenous and intratecal clonidine for postoperative analgesia of patients submitted to laparoscopic cholecystectomy: randomized clinical trial

Introduction and objectives

Alpha2 adrenergic agonists, such as clonidine, are used as adjuvants during anesthesia due to their analgesic, sedative, and cardiovascular effects. The objective of the present study was to compare the effect of clonidine administered intravenously and intrathecally on the postoperative pain score of patients undergoing laparoscopic cholecystectomy, according to the route of administration and postoperative opioid consumption.

Methods

This randomized clinical trial, blind to patients and evaluator, assessed 60 patients, candidates for elective laparoscopic cholecystectomy under standardized general anesthesia techniques. Patients were randomly allocated into three groups (20 in each group): Control Group (CG), Intrathecal Clonidine Group (ITCG), and Intravenous Clonidine Group (IVCG). The primary outcome was the comparison of pain, Blood Pressure (BP) and Heart Rate (HR) scores among groups. The secondary outcome was report of adverse effects such as bradycardia, hypotension and sedation, and the need for rescue medication.

Results

The mean age was 37.2 ± 8.2 years, and the mean body mass was 28.3 ± 3.6 kg.m^-2. Regarding HR (p = 0.003) and pain (p = 0.027), patients in ITCG and CG showed a different profile over time, with CG showing higher consumption of morphine as rescue medication (p = 0.005).

Conclusion

The administration of intrathecal and intravenous clonidine in low doses can reduce hemodynamic parameters and decrease postoperative requirement of analgesics. Further studies should investigate the ideal dose and method.

Effect of preoperative administration of systemic alpha-2 agonists on postoperative pain: a systematic review and meta-analysis

Background

Alpha-2 agonists have sedative, analgesic, and opioid-sparing effects. Moreover, intraoperative or postoperative systemic administration of alpha-2 adrenergic agonists is known to reduce postoperative pain and opioid consumption. This meta-analysis investigated whether preoperative administration of alpha-2 agonists can affect postoperative pain and opioid consumption.

Methods

We searched the MEDLINE, EMBASE, Cochrane Library (CENTRAL), KoreaMed, and KMbase databases through March 2019 to identify relevant randomized controlled trials (RCTs) on the effect of preoperative systemic administration of alpha-2 agonists on postoperative pain and opioid consumption. We conducted a meta-analysis according to the Cochrane Collaboration guidelines. Standardized mean differences (SMDs) of postoperative pain intensity or dose of opioid consumption in the alpha-2 agonist group were extracted and combined using a random-effect model and were compared to those of the control group.

Results

Eleven RCTs involving 748 participants were included in this meta-analysis. Preoperative administration of systemic alpha-2 agonists significantly reduced cumulative opioid consumption up to 6 h (SMD, –0.52; 95% confidence interval [–0.90 to –0.14]) and 24 h (SMD, –0.68 [–1.27 to –0.09]) after surgery. Moreover, preoperative administration of alpha-2 agonists significantly reduced postoperative pain intensity at 6 h (SMD, –0.50 [–0.78 to –0.21]) and 24 h (SMD, –0.44 [–0.86 to –0.03]).

Conclusions

In this meta-analysis, high degree of heterogeneity limits the preoperative administration of alpha-2 agonists in reducing postoperative opioid consumption and pain intensity. Future powered large RCTs are required to increase the certainty of evidence on the effect in reducing postoperative opioid consumption and pain intensity.

Alpha-2 adrenergic agonists for the prevention of cardiac complications among adults undergoing surgery

BACKGROUND

The surgical stress response plays an important role on the pathogenesis of perioperative cardiac complications. Alpha-2 adrenergic agonists attenuate this response and may help prevent postoperative cardiac complications.

OBJECTIVES

To determine the efficacy and safety of α-2 adrenergic agonists for reducing mortality and cardiac complications in adults undergoing cardiac surgery and non-cardiac surgery.

SEARCH METHODS

We searched CENTRAL (2017, Issue 4), MEDLINE (1950 to April Week 4, 2017), Embase (1980 to May 2017), the Science Citation Index, clinical trial registries, and reference lists of included articles.

SELECTION CRITERIA

We included randomized controlled trials that compared α-2 adrenergic agonists (i.e. clonidine, dexmedetomidine or mivazerol) against placebo or non-α-2 adrenergic agonists. Included trials had to evaluate the efficacy and safety of α-2 adrenergic agonists for preventing perioperative mortality or cardiac complications (or both), or measure one or more relevant outcomes (i.e. death, myocardial infarction, heart failure, acute stroke, supraventricular tachyarrhythmia and myocardial ischaemia).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality, extracted data and independently performed computer entry of abstracted data. We contacted study authors for additional information. Adverse event data were gathered from the trials. We evaluated included studies using the Cochrane 'Risk of bias' tool, and the quality of the evidence underlying pooled treatment effects using GRADE methodology. Given the clinical heterogeneity between cardiac and non-cardiac surgery, we analysed these subgroups separately. We expressed treatment effects as pooled risk ratios (RR) with 95% confidence intervals (CI).

MAIN RESULTS

We included 47 trials with 17,039 participants. Of these studies, 24 trials only included participants undergoing cardiac surgery, 23 only included participants undergoing non-cardiac surgery and eight only included participants undergoing vascular surgery. The α-2 adrenergic agonist studied was clonidine in 21 trials, dexmedetomidine in 24 trials and mivazerol in two trials.In non-cardiac surgery, there was high quality evidence that α-2 adrenergic agonists led to a similar risk of all-cause mortality compared with control groups (1.3% with α-2 adrenergic agonists versus 1.7% with control; RR 0.80, 95% CI 0.61 to 1.04; participants = 14,081; studies = 16). Additionally, the risk of cardiac mortality was similar between treatment groups (0.8% with α-2 adrenergic agonists versus 1.0% with control; RR 0.86, 95% CI 0.60 to 1.23; participants = 12,525; studies = 5, high quality evidence). The risk of myocardial infarction was probably similar between treatment groups (RR 0.94, 95% CI 0.69 to 1.27; participants = 13,907; studies = 12, moderate quality evidence). There was no associated effect on the risk of stroke (RR 0.93, 95% CI 0.55 to 1.56; participants = 11,542; studies = 7; high quality evidence). Conversely, α-2 adrenergic agonists probably increase the risks of clinically significant bradycardia (RR 1.59, 95% CI 1.18 to 2.13; participants = 14,035; studies = 16) and hypotension (RR 1.24, 95% CI 1.03 to 1.48; participants = 13,738; studies = 15), based on moderate quality evidence.There was insufficient evidence to determine the effect of α-2 adrenergic agonists on all-cause mortality in cardiac surgery (RR 0.52, 95% CI 0.26 to 1.04; participants = 1947; studies = 16) and myocardial infarction (RR 1.01, 95% CI 0.43 to 2.40; participants = 782; studies = 8), based on moderate quality evidence. There was one cardiac death in the clonidine arm of a study of 22 participants. Based on very limited data, α-2 adrenergic agonists may have reduced the risk of stroke (RR 0.37, 95% CI 0.15 to 0.93; participants = 1175; studies = 7; outcome events = 18; low quality evidence). Conversely, α-2 adrenergic agonists increased the risk of bradycardia from 6.4% to 12.0% (RR 1.88, 95% CI 1.35 to 2.62; participants = 1477; studies = 10; moderate quality evidence), but their effect on hypotension was uncertain (RR 1.19, 95% CI 0.87 to 1.64; participants = 1413; studies = 9; low quality evidence).These results were qualitatively unchanged in subgroup analyses and sensitivity analyses.

AUTHORS' CONCLUSIONS

Our review concludes that prophylactic α-2 adrenergic agonists generally do not prevent perioperative death or major cardiac complications. For non-cardiac surgery, there is moderate-to-high quality evidence that these agents do not prevent death, myocardial infarction or stroke. Conversely, there is moderate quality evidence that these agents have important adverse effects, namely increased risks of hypotension and bradycardia. For cardiac surgery, there is moderate quality evidence that α-2 adrenergic agonists have no effect on the risk of mortality or myocardial infarction, and that they increase the risk of bradycardia. The quality of evidence was inadequate to draw conclusions regarding the effects of alpha-2 agonists on stroke or hypotension during cardiac surgery.

Effect of Oral Clonidine on Shoulder Tip Pain and Hemodynamic Response After Laparoscopic Cholecystectomy: A Randomized Double Blind Study

Background

Shoulder tip pain is a common problem after laparoscopic cholecystectomy. There are a few clinical trial studies on the effect of clonidine on post laparoscopic shoulder pain (PLSP). This study aimed at evaluating the effect of oral clonidine on PLSP in semi-sitting position and post-operative hemodynamic response of patients undergoing LC surgery.

Methods

This randomized controlled clinical trial was conducted on 60 patients, who were candidates for elective laparoscopic cholecystectomy surgery under general anesthesia, and were randomly allocated to clonidine and placebo groups. Patients in the clonidine group received 0.2 mg oral, 90 minutes prior to induction. Patients in the placebo group received vitamin C tablets during the same time. Postoperative pain intensity was assessed, using a visual analog scale at the emergence from anesthesia, 4 and 8 hours after the operation by an anesthetist, who was blinded to the patient group. Mean arterial blood pressure and heart rate were recorded before clonidine administration and in post-operative period.

Results

The mean age was 36.85 ± 10.93 years and the mean Body Mass was 26.34 ± 3.46 kg/m². Two groups were not comparable with respect to occurrence of PLSP (P = 0.739). There was a significant difference in intensity of PLSP between the 2 groups at emergence from anesthesia (P = 0.012), 4 and 8 hours after the operation (P = 0.001) between 2 groups. The clonidine group showed a larger reduction of pain intensity at these phases. The result of independent t test indicated significant differences in the MABP value between the 2 groups at the time of emergence from anesthesia (P = 0.031). The clonidine group demonstrated a lower MABP level at this time.

Conclusions

Oral clonidine is not effective in preventing the PLSP. However, it alleviates PLSP intensity in the patient under LC procedure on the first post-operative hours.

The Effect of Pre-Emptive Dexmedetomidine on the Incidence of Post-Thoracotomy Pain Syndrome in Patients Undergoing Coronary Artery Bypass Grafting

Background

Post-thoracotomy pain syndrome (PTPS) is pain that recurs or persists along a thoracotomy incision for at least two months following surgery. Dexmedetomidine (dex) is an α-2 agonist that also has analgesic, sedative-hypnotic, and sympatholytic properties.

Objectives

To determine the effect of pre-emptive dexmedetomidine on the incidence of PTPS in patients undergoing coronary artery bypass grafting (CABG).

Patients and Methods

This randomized clinical trial enrolled 104 candidates for elective coronary artery bypass grafting (CABG) and randomly assigned them to either a dex group or a control group. In the dex group, dexmedetomidine 0.5 µg/kg/hour was infused from the initiation of anesthesia until postoperative extubation in the intensive-care unit. Two months after surgery, the patients were contacted by telephone and interviewed to determine the presence of pain at the thoracotomy scars.

Results

Fifty-four patients were placed in the control group, and 50 patients were assigned to the dex group. The age, sex, and body mass index were not significantly different between the two groups of study (P > 0.05). The incidence of PTPS was 11/50 (22%) patients in the dex group and 28/54 patients (52%) in the control group. A chi-square test revealed a significant difference in the incidence of PTPS after two months between the dex and control groups (P = 0.032).

Conclusions

PTPS is a common problem following CABG, and pre-emptive therapy with dex may decrease neuropathic pain.

Effects of dexmedetomidine and clonidine as propofol adjuvants on intra-operative hemodynamics and recovery profiles in patients undergoing laparoscopic cholecystectomy: A prospective randomized comparative study

Context:

Alpha-2 (α2) adrenergic receptor agonists, clonidine and dexmedetomidine, are widely used as adjuvants during anesthesia for analgesic, sedative, sympatholytic, and cardiovascular stabilizing effects.

Aims:

We compared effects of clonidine and dexmedetomidine (as propofol adjuvants) on intra-operative hemodynamics, recovery time, and postoperative cognitive function impairment.

Subjects and Methods:

Forty-five American Society of Anesthesiologists I and II patients, scheduled for laparoscopic cholecystectomy were divided into three groups (n = 15). Group C patients received bolus of clonidine 3 μg/kg followed by a continuous infusion; Group D patients received dexemedetomidine 1 μg/kg and a continuous infusion; and Group P patients received a bolus of normal saline followed by an infusion. Intra-operative mean arterial pressure (MAP) and pulse rate (PR) were measured throughout the surgery. Bispectral index was maintained at 55 ± 5 by titrating propofol infusion rate. The time between the interruption of anesthesia and eye opening (recovery time) was measured. Cognitive function was assessed using short mental status questionnaire at 15, 30, 45, and 60 min postoperatively.

Results:

The sympathetic response to laryngoscopy and extubation on MAP and PR were significantly reduced with the use of clonidine and dexmedetomidine (P < 0.05). The recovery was delayed (P < 0.05) with both the drug combinations and it was more pronounced with dexmedetomidine (P < 0.05). Dexmedetomidine group showed cognitive impairment in a postoperative period lasting up to an hour.

Conclusions:

When co-administered with propofol, both clonidine, and dexmedetomidine attenuate sympathetic response to laryngoscopy and extubation but cause delay in the recovery from anesthesia. Dexmedetomidine causes impairment of postoperative cognitive functions.