Late intraoperative clonidine administration prevents postanesthetic shivering after total intravenous or volatile anesthesia

Effect of intrathecal lipophilic opioids on the incidence of shivering in women undergoing cesarean delivery after spinal anesthesia: a systematic review and bayesian network meta- analysis of randomized controlled trials

Background

Shivering is a common side effect in women having cesarean delivery (CD) under spinal anesthesia, which can be bothersome to the patient, and it can also interfere with perioperative monitoring. In several studies, the intrathecal (IT) addition of a lipophilic opioid to local anesthetics has been shown to decrease the incidence of shivering.

Objective

We performed this network meta-analysis to evaluate the effects of intrathecal lipophilic opioids in preventing the incidence of shivering in patients undergoing CD.

Methods

This review was planned according to the PRISMA for Network Meta-Analysis (PRISMA-NMA) guidelines. An English literature search of multiple electronic databases was conducted. We included randomized controlled trials (RCTs) that reported on the incidence of shivering, with study groups receiving either IT fentanyl, sufentanil, or meperidine in women undergoing CD under spinal anesthesia. Quality of the studies was assessed using the modified Oxford scoring system. Using random-effects modeling, dichotomous data were extracted and summarized using odds ratio (OR) with a 95% credible interval (CrI). Statistical analysis was conducted using R studio version 1.0.153 - Inc.

Results

Twenty-one studies consisting of 1433 patients (Control group: 590 patients in twenty-one studies; Fentanyl group:199 patients in seven studies; Sufentanil group: 156 patients in five studies; Meperidine group: 488 patients in ten studies) met the inclusion criteria for this systematic review investigating the effect of intrathecal lipophilic opioids in preventing the incidence of shivering in women undergoing cesarean delivery under spinal anesthesia. Methodological validity scores ranged from 3 to 7. The Bayesian mixed network estimate showed the incidence of shivering was significantly lower with IT fentanyl (pooled odds ratio (OR): 0.13; 95% credible interval (CrI): 0.04 to 0.35; P = 0.0004) and IT meperidine (OR: 0.12; 95% CrI: 0.05 to 0.29; P < 0.00001), but not with IT sufentanil (OR: 0.37; 95% CrI: 0.11 to 1.22; P = 0.23). The IT fentanyl group had a significantly lower incidence of intraoperative discomfort [Risk Ratio (RR): 0.19; 95% CI: 0.10–0.35; P < 0.00001], the IT sufentanil group had a significantly higher incidence of pruritus (RR: 6.18; 95% CI: 1.18–32.46; P = 0.03) The IT meperidine group had a significantly lower incidence of intraoperative discomfort (2.7% vs. 13.6%; RR: 0.22; 95% CI: 0.09–0.55; P = 0.001), but there was a significant increase in nausea and vomiting (IT meperidine group vs. Control group: 42.7% vs. 19.4%; RR: 2.56; 95% CI: 1.14–5.75; P = 0.02). Meta-regression analysis based on the opioid dose and quality of the study did not impact the final inference of our result.

Conclusion

IT fentanyl significantly decreased the incidence of shivering in women undergoing CD under spinal anesthesia without increasing maternal adverse events, confirming that routine use in this patient population is a good choice. IT sufentanil did not decrease the incidence of shivering. IT meperidine decreased the incidence and severity of shivering, but its use was also associated with significant nausea and vomiting.

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.

Comparison of postoperative analgesic effect of intrathecal clonidine and fentanyl added to bupivacaine in patients undergoing cesarean section: a prospective randomized double-blind study

Objectives. To compare the analgesic efficacy of intrathecal clonidine and fentanyl added to bupivacaine after cesarean section. Methods. Ninety patients scheduled for cesarean section under spinal anesthesia were randomly allocated to one of the three following groups to receive bupivacaine 10 mg combined with 75 µg clonidine (group C), bupivacaine 10 mg combined with 0.5 mL fentanyl (group F), and bupivacaine 10 mg combined with 0.5 mL distilled water (group P), intrathecally. The time to first analgesic request, analgesic requirement in the first 24 hours after surgery, sensory and motor blockade onset time, duration of sensory and motor blockade, the incidence of hypotension, ephedrine requirements, bradycardia, and hypoxemia were recorded. Results. The duration of anesthesia in clonidine group (275.10 ± 96.09) was longer compared to the placebo (211.73 ± 74.80) and fentanyl (192.33 ± 30.36) groups. This difference between group C versus F (P = 0.006) and P groups (P < 0.001) was significant. Similarly, the mean time to first analgesic request was also longer in group C (519.44 ± 86.25) than in groups F (277.88 ± 94.25) and P (235.43 ± 22.35 min). This difference between group C versus F (P < 0.001) and P groups (P < 0.001) was significant. Conclusion. Intrathecal clonidine 75 µg with bupivacaine prolonged the time to first analgesic request compared to fentanyl; however, the total analgesic consumption within the first 24 h postoperative was similar in fentanyl and clonidine groups following cesarean section. This trial is registered with ACTRN12611000909921 and ClinicalTrials.gov NCT01425658.

Intrathecal Meperidine Plus Lidocaine for Prevention of Shivering during Cesarean Section

Background

Shivering related to spinal anesthesia may interfere with monitoring and is uncomfortable. The aim of the present study was to investigate low-dose intrathecal meperidine for the prevention of shivering after induction of spinal anesthesia in parturients with cesarean section.

Methods

This was a prospective randomized, double-blind, placebo-controlled trial including 100 parturients, of American Society of Anesthesiologists (ASA) physical status I or II, scheduled for elective cesarean section under spinal anesthesia who were randomly assigned to a meperidine (0.2 mg/kg) plus hyperbaric lidocaine (5%, 75 mg, n = 50; group M) group or a placebo plus hyperbaric lidocaine (5%, 75 mg, n = 50; group L) group. Demographic and surgical data, adverse events, and the mean intensity for each parturient were assessed during the entire study period by a blinded observer.

Results

There were no significant differences between the two study groups regarding the demographic and surgical data (P > 0.05). The incidence of shivering during the entire study period significantly decreased in the group of parturients who received intrathecal meperidine (P = 0.04). There were no significant differences in nausea and vomiting between the two groups.

Conclusions

Low-dose intrathecal meperidine (10 mg) is safe and effective in reducing the incidence and severity of shivering associated with spinal anesthesia in parturients with cesarean section.

Are the pharmacology and physiology of α₂ adrenoceptors determined by α₂-heteroreceptors and autoreceptors respectively?

α(2)-Adrenoceptors are important mediators of physiological responses to the endogenous catecholamines noradrenaline and adrenaline. In addition, α(2)-adrenoceptors are pharmacological targets for the treatment of hypertension, sympathetic overactivity and glaucoma. α(2)-Adrenoceptors are also targeted to induce sedation and analgesia in anaesthesia and intensive care. α(2)-Adrenoceptors were first described as presynaptic receptors inhibiting the release of various transmitters from neurons in the central and peripheral nervous systems. In addition to these presynaptic neuronal receptors, α(2)-adrenoceptors were also identified in many non-neuronal cell types of the body. Gene-targeting in mice provided a comprehensive assignment of the physiological and pharmacological functions of these receptors to specific α(2A)-, α(2B) - and α(2C)-adrenoceptor subtypes. However, the specific cell types and signalling pathways involved in these subtype-specific α(2)-adrenoceptor functions were largely unexplored until recently. This review summarizes recent findings from transgenic mouse models, which were generated to define the role of α(2)-adrenoceptors in adrenergic neurons, that is, α(2)-autoreceptors, versus α(2)-adrenoceptors in non-adrenergic neurons, termed α(2)-heteroreceptors. α(2)-Autoreceptors are primarily required to limit release of noradrenaline from sympathetic nerves and adrenaline from adrenal chromaffin cells at rest. These receptors are desensitized upon chronic activation as it may for instance occur due to enhanced sympathetic activity during chronic heart failure. In contrast, pharmacological effects of acutely administered α(2)-adrenoceptor agonist drugs essentially require α(2)-heteroreceptors in non-adrenergic neurons, including analgesia, sedation, hypothermia and anaesthetic-sparing as well as bradycardia and hypotension. Thus a clear picture has emerged of the significance of auto- versus heteroreceptors in mediating the physiological functions of α(2)-adrenoceptors and the pharmacological functions of α(2)-adrenoceptor agonist drugs respectively.

Control of shivering with clonidine, butorphanol, and tramadol under spinal anesthesia: a comparative study

INTRODUCTION

The present study was designed to evaluate the efficacy of clonidine, butorphanol, and tramadol in control of shivering under spinal anesthesia, and to compare their side effects.

METHODS

This randomized, prospective study was conducted in 90 patients who developed shivering under spinal anesthesia during various abdominal or orthopedic surgery procedures. On shivering, patients were randomly allocated to receive an intravenous, 1 mL bolus dose of 50 mg tramadol, or 1 mg butorphanol, or 150 μg clonidine, in a double blinded manner. Control of shivering, time taken for cessation, recurrence, hemodynamic changes, axillary temperatures, and side effects were noted and compared for all 3 groups. Collected data were analyzed using appropriate statistical tests.

RESULTS

Butorphanol and tramadol were more effective than clonidine in suppressing shivering. Butorphanol, tramadol, and clonidine completely controlled rigors in 83%, 73%, and 53% of cases, respectively, and incompletely suppressed rigors in 16%, 26%, and 46% of cases, respectively. Time taken to terminate rigors was significantly higher for clonidine (3.3 ± 0.9 minutes) than for butorphanol and tramadol (2.1 ± 1.0 minutes and 1.8 ± 0.5 minutes; P < 0.001).

CONCLUSION

Butorphanol had an edge over tramadol in controlling shivering with lower chances of recurrence, though both were superior to clonidine for this purpose with an early onset of action. We conclude that both these opioids control rigors better than α-2 agonists.

Aspects of thermoregulation physiology

PURPOSE OF REVIEW

The review covers the main aspects of thermoregulation physiology and highlights the implications for therapeutic hypothermia trials. Prevention of shivering and other hypothermia side-effects is of key importance because controlling thermoregulatory responses may be essential for demonstrating neuro-protective properties of hypothermia in several pathologic conditions in which its role is still uncertain, such as in traumatic brain injury and stroke.

RECENT FINDINGS

Several recommendations and clinical reviews have been produced in the past 2 years about the application and feasibility of therapeutic hypothermia. Many drugs have been tested in healthy volunteers and anaesthetized patients to abolish shivering but the best protocol for managing side-effects has not yet been defined. A possible strategy might be to simultaneously apply physical methods, such as skin warming, and combination drug therapy. Different drug protocols can be applied, depending on the nature of the care setting.

SUMMARY

During moderate hypothermia treatment, conducted in an intensive care environment, shivering can be treated with sedatives, opioids (meperidine in particular), and α2-agonists, combined with active skin counter-warming. However, new randomized controlled clinical trials in intensive care patients are required to improve our knowledge regarding this treatment.

Single-Dose Parenteral Pharmacological Interventions for the Prevention of Postoperative Shivering: A Quantitative Systematic Review of Randomized Controlled Trials

Shivering is a frequent complication in the postoperative period. The relative efficacy of pharmacological interventions to prevent this phenomenon is not well understood. We performed a systematic search for full reports of randomized comparisons of prophylactic, parenteral, single-dose antishivering interventions with inactive control (placebo or no treatment). Variable doses were converted to fixed doses. Dichotomous data on the absence of shivering were analyzed by using relative benefit (RB) and number needed to treat (NNT) with 95% confidence intervals (CI). Data from 27 trials (1348 adults received an antishivering intervention; 931 were controls) were analyzed. The average incidence of shivering in controls was extremely frequent (52%). Clonidine 65-300 microg (1078 patients), meperidine 12.5-35 mg (250 patients), tramadol 35-220 mg (250 patients), and nefopam 6.5-11 mg (204 patients) were tested in at least 3 trials each. All were more effective than control. For clonidine, meperidine, and nefopam, there was some weak evidence of dose responsiveness. For small-dose clonidine (65-110 microg), the RB compared with control was 1.32 (95% CI, 1.16-1.51); for medium-dose clonidine (140-150 microg), the RB was 1.83 (95% CI, 1.47-2.27); and for large-dose clonidine (220-300 microg), the RB was 1.52 (95% CI, 1.30-1.78). For all clonidine regimens combined, the RB was 1.58 (95% CI, 1.43-1.74), with an NNT of 3.7. For all meperidine regimens combined, the RB was 1.67 (95% CI, 1.37-2.03), with an NNT of 3. For all tramadol regimens combined, the RB was 1.93 (95% CI, 1.56-2.39), with an NNT of 2.2. For all nefopam regimens combined, the RB was 2.62 (95% CI, 2.02-3.40), with an NNT of 1.7. Methylphenidate, midazolam, dolasetron, ondansetron, physostigmine, urapidil, and flumazenil were tested in no more than 3 trials each, with a limited number of patients.

Postanaesthetic shivering: epidemiology, pathophysiology, and approaches to prevention and management

Along with nausea and vomiting, postanaesthetic shivering is one of the leading causes of discomfort for patients recovering from general anaesthesia. The distinguishing factor during electromyogram recordings between patients with postanaesthetic shivering and shivering in fully awake patients is the existence of clonus similar to that recorded in patients with spinal cord transection. Clonus coexists with the classic waxing and waning signals associated with cutaneous vasoconstriction (thermoregulatory shivering). The primary cause of postanaesthetic shivering is peroperative hypothermia, which sets in because of anaesthetic-induced inhibition of thermoregulation. However, shivering associated with cutaneous vasodilatation (non-thermoregulatory shivering) also occurs, one of the origins of which is postoperative pain. Apart from causing discomfort and aggravation of pain, postanaesthetic shivering increases metabolic demand proportionally to the solicited muscle mass and the cardiac capacity of the patient. No link has been demonstrated between the occurrence of shivering and an increase in cardiac morbidity, but it is preferable to avoid postanaesthetic shivering because it is oxygen draining. Prevention mainly entails preventing peroperative hypothermia by actively rewarming the patient. Postoperative skin surface rewarming is a rapid way of obtaining the threshold shivering temperature while raising the skin temperature and improving the comfort of the patient. However, it is less efficient than certain drugs such as meperidine, clonidine or tramadol, which act by reducing the shivering threshold temperature.

Postoperative shivering: aetiology and treatment

Most postanaesthetic shivering-like tremor is normal thermoregulatory shivering in response to core hypothermia. Therefore, shivering will be prevented by maintaining intraoperative normothermia. Other thermoregulatory-related shivering is caused by the release of cytokines by the surgical procedure. Non-thermoregulatory shivering, occurring in normothermic patients, is caused by other aetiologies such as postoperative pain. It is thus likely that adequate treatment of postoperative pain will ameliorate non-thermoregulatory tremor. In addition, the administration of antipyretic drugs reduces shivering in patients after cardiopulmonary bypass surgery.

Thermal regulation and mild intraoperative hypothermia

Homeothermic species such as birds and mammals require an almost constant internal body temperature to preserve normal physiological and metabolic function. When the internal temperature deviates significantly from normal, metabolic function deteriorates and death may result. The efficiency of the thermoregulatory system is highly affected by the administration of medication and by illnesses. Hypothermia may result, especially when these conditions are associated with exposure to a cold environment. Because such conditions exist during anaesthesia and surgery, the understanding of the physiology of the thermoregulatory system and the associated perianaesthetic thermal disturbances is essential to a proper intraoperative management. The purpose of this review is to provide clinicians with a better understanding of these principles, and also to elaborate on the most recent advances in this field, which should help to improve intraoperative anaesthetic temperature management.