Oral clonidine pretreatment for haemodynamic stability during craniotomy

Intravenous Fentanyl 4 μg per kg Administered before Scalp Pin Application is Inferior to Scalp Block in Preventing Hemodynamic Changes

Background:

Application of scalp pins for craniotomy surgeries is a noxious stimulus, causing tachycardia and hypertension, resulting in increased cerebral blood flow and elevated intracranial pressure, hence measures to attenuate this will have beneficial role.

Aims:

The aim is to compare the effectiveness of scalp block (SB) to 4 μg.kg^-1 intravenous (i.v) fentanyl in attenuating hemodynamic response to scalp pin application in patients who underwent elective craniotomy under general anesthesia.

Settings and Design:

The study design involves prospective, randomized study conducted at Tertiary care center/hospital.

Subjects and Methods:

Forty-four American Society of Anesthesiologists physical status Classes l and II patients were randomly allocated into the following groups: Group-SB (n = 22) received SB using 0.25% injection bupivacaine and Group-F (n = 22) received 1 μg.kg^-1 i.v fentanyl. Patient's heart rate (HR) and mean arterial pressure (MAP) were recorded from the application of pins till 60 min and rescue analgesic/anesthetic agents and their dosage were noted. Statistical analysis was performed comparing HR and MAP changes to application of scalp pins.

Statistical Analysis:

Software developed by the Centre for Disease Control, Atlanta, namely Epidemiological Information Package 2010 was used to derive statistical variables.

Results:

Patients were comparable in age, gender, hypertension as comorbidity, baseline HR, and MAP. Significant rise in HR was noted in Group-F till 20^th min compared to Group-SB. MAP was high from application of pins till 60^th min in Group-F compared to Group-SB. Requirement of rescue analgesics/anesthetics was high in Group-F compared to Group-SB.

Conclusion:

SB effectively attenuates hemodynamic response to application of scalp pins in patients undergoing elective craniotomy and reduces requirement of rescue analgesic and/or anesthetics.

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.

A novel application for bolus remifentanil: blunting the hemodynamic response to Mayfield skull clamp placement

OBJECTIVE

Neurosurgery often requires skull immobilization with a Mayfield clamp, which often causes brief intense nociceptive stimulation, hypertension and tachycardia. Blunting this response may help prevent increased intracranial pressure, cerebral aneurysm or vascular malformation rupture, and/or myocardial stress. While various interventions have been described to blunt this response, no reports have compared administration of a propofol versus a remifentanil bolus.

METHODS

We retrospectively analyzed the hemodynamic response to Mayfield placement in over 800 patients who received a prior propofol or remifentanil bolus from 2004 to 2010.

RESULTS

Patients who received remifentanil experienced a 55% smaller increase in heart rate (p < 0.0001) and a 40% smaller increase in systolic blood pressure (p < 0.0001) after Mayfield placement than patients who received propofol. These data were retrospectively obtained from patients who were not randomized to receive remifentanil versus propofol, and hence these data could be subject to possible confounding. Nonetheless, these differences remained significant after multivariate analysis for possible confounding variables.

CONCLUSIONS

Thus, a remifentanil bolus is more effective than a propofol bolus in blunting hemodynamic responses to Mayfield placement, and possibly for other short, intense nociceptive stimuli.

The effects of clonidine premedication and scalp infiltration of lidocaine on hemodynamic responses to laryngoscopy and skull pin head-holder insertion during skull base procedures

This study was designed to determine if oral clonidine or lidocaine, injected into the scalp before head-holder (H-H) insertion, would attenuate the hemodynamic effects associated with intubation and H-H placement. Thirty-four patients undergoing skull base procedures were randomized to four groups. Group 1 received clonidine 5 mcg/kg po before surgery with 10 to 15 ml of 1% lidocaine infiltrated at pin insertion sites; Group 2 received clonidine with saline infiltration; Group 3 received a placebo preoperatively and had lidocaine infiltrated at pin sites; and Group 4 received a placebo with saline infiltrated. All patients had a standard anesthetic titrated to a 10 to 14 Hz EEG endpoint during laryngoscopy and H-H placement. Mean arterial pressure (MAP) was similar between groups during intubation, but heart rate (HR) increased in patients who did not receive clonidine. H-H application increased HR and MAP in Group 4. HR also increased after H-H placement in patients who received oral clonidine, while patients receiving scalp lidocaine or both clonidine and scalp lidocaine had little change in either value. Clonidine attenuated HR increases after laryngoscopy but not after H-H placement. Lidocaine injected at the pin sites reduced HR, and MAP increased after H-H insertion. The combination of oral clonidine and scalp lidocaine blunted hemodynamic responses to both intubation and H-H placement.

[Neuroanaesthesia. Principles of optimized perioperative management]

Because of the high vulnerability of the brain as a primary target, neuroanaesthesia requires a close look at basic physiological principles and factors of influence during surgery and subsequent intensive care. Anticipatory management is crucial for anaesthesia within the scope of neurosurgical interventions: essential components of anaesthesia management must already be prepared before the surgical procedure. Intracranial compliance and pressure determine the patient's fate; accordingly they have to be assessed correctly and measured continuously. Advanced methods of monitoring allow sophisticated and individually focused treatment thus contributing to patient safety. Only few pharmacologic approaches have been proven with solid evidence, yet some new studies have revealed interesting brain protective effects of pharmacological and/or adjuvant therapeutic measures. For the treatment of intracranial hypertension, osmotherapy is still of the highest value. Decompressive craniotomy seems to have become a promising alternative, although this must be judged to date as a last resort therapy. Perioperative care of patients with complex intracranial pathologies thus needs a close interaction and cooperation between the operation theatre and intensive care units in the sense of continuous track anaesthesia.

Alpha-2 adrenergic agonists for the prevention of cardiac complications among patients 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 thereby prevent cardiac complications.

OBJECTIVES

This review assessed the efficacy and safety of preoperative (within 24 hours), intraoperative, and postoperative (first 48 hours) alpha-2 adrenergic agonists for preventing mortality and cardiac complications after surgery performed under either general or neuraxial anaesthesia, or both.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 3), MEDLINE (1950 to August week 4 2008), EMBASE (1980 to week 36 2008), the Science Citation Index, and reference lists of articles.

SELECTION CRITERIA

We included randomized controlled trials that compared alpha-2 adrenergic agonists (clonidine, dexmedetomidine, or mivazerol) against placebo or non-alpha-2 adrenergic agonists. Included studies had to report on mortality, myocardial infarction, myocardial ischaemia, or supraventricular tachyarrhythmia.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed trial quality and extracted data. Two authors independently performed computer entry of abstracted data. We contacted study authors for additional information. Adverse event data were gathered from the trials.

MAIN RESULTS

We included 31 studies (4578 participants). Study quality was generally inadequate, with only six studies clearly reporting methods for blinding and allocation concealment. Overall, alpha-2 adrenergic agonists reduced mortality (relative risk (RR) 0.66; 95% CI 0.44 to 0.98; P = 0.04) and myocardial ischaemia (RR 0.68; 95% CI 0.57 to 0.81; P < 0.0001). However, their effects appeared to vary with the surgical procedure. The most encouraging data pertained to vascular surgery, where they reduced mortality (RR 0.47; 95% CI 0.25 to 0.90; P = 0.02), cardiac mortality (RR 0.36; 95% CI 0.16 to 0.79; P = 0.01), and myocardial infarction (RR 0.66; 95% CI 0.46 to 0.94; P = 0.02). With regard to adverse effects, alpha-2 adrenergic agonists significantly increased perioperative hypotension (RR 1.32; 95% CI 1.07 to 1.62; P = 0.009) and bradycardia (RR 1.66; 95% CI 1.14 to 2.41; P = 0.008).

AUTHORS' CONCLUSIONS

Our study provides encouraging evidence that alpha-2 adrenergic agonists may reduce cardiac risk, especially during vascular surgery. Nonetheless, these data remain insufficient to make firm conclusions about their efficacy and safety. A large randomized trial of alpha-2 adrenergic agonists is therefore warranted. Additionally, future research must determine which specific alpha-2 adrenergic agonist should be used, and whether it is safe to combine them with other perioperative interventions (for example beta-adrenergic blockade).

Dexmedetomidine as an anaesthetic adjuvant in patients undergoing intracranial tumour surgery: a double-blind, randomized and placebo-controlled study †

BACKGROUND

Dexmedetomidine (DEX) has been shown to provide good perioperative haemodynamic stability with decreased intraoperative opioid requirements. It may have neural protective effects, and thus may be a suitable anaesthetic adjuvant to neurosurgical anaesthesia.

METHODS

Fifty-four patients scheduled for elective surgery of supratentorial brain tumour were randomized to receive in a double-blind manner a continuous DEX infusion (plasma target concentration 0.2 or 0.4 ng ml(-1)) or placebo, beginning 20 min before anaesthesia and continuing until the start of skin closure. The DEX groups received fentanyl 2 microg kg(-1) at the induction of anaesthesia and before the start of operation, the placebo group 4 microg kg(-1), respectively. Anaesthesia was maintained with nitrous oxide in oxygen and isoflurane.

RESULTS

The median times from the termination of N2O to extubation were 6 (3-27), 3 (0-20) and 4 (0-13) min in placebo, DEX-0.2 and DEX-0.4 groups, respectively (P<0.05 anova all-over effect). The median percentage of time points when systolic blood pressure was within more or less than 20% of the intraoperative mean was 72, 77 and 85, respectively (P<0.01), DEX-0.4 group differed significantly from the other groups. DEX blunted the tachycardic response to intubation (P<0.01) and the hypertensive response to extubation (P<0.01). DEX-0.4 group differed in the heart rate variability from placebo (93 vs 82%, P<0.01).

CONCLUSIONS

DEX increased perioperative haemodynamic stability in patients undergoing brain tumour surgery. Compared with fentanyl, the trachea was extubated [corrected] faster without respiratory depression.

Factors influencing preoperative stress response in coronary artery bypass graft patients

Background

In many studies investigating measures to attenuate the hemodynamic and humoral stress response during induction of anaesthesia, primary attention was paid to the period of endotracheal intubation since it has been shown that even short-lasting sympathetic cardiovascular stimulation may have detrimental effects on patients with coronary artery disease. The aim of this analysis was, however, to identify the influencing factors on high catecholamine levels before induction of anaesthesia.

Methods

Various potential risk factors that could impact the humoral stress response before induction of anaesthesia were recorded in 84 males undergoing coronary aortic bypass surgery, and were entered into a stepwise linear regression analysis. The plasma level of norepinephrine measured immediately after radial artery canulation was chosen as a surrogate marker for the humoral stress response, and it was used as the dependent variable in the regression model. Accordingly, the mean arterial blood pressure, heart rate and the calculated pressure-rate product were taken as parameters of the hemodynamic situation.

Results

Stepwise regression analysis revealed that the oral administration of low-dose clonidine (mean dose 1.75 μg·kg^-1) on the morning of surgery was the only significant predictor (p = 0.004) of the high variation in preoperative norepinephrine plasma levels. This intervention decreased norepinephrine levels by more than 40% compared to no clonidine administration, from 1.26 to 0.75 nmol·l^-1. There was no evidence for dose-responsiveness of clonidine. All other potential predictors were removed from the model as insignificant (p > 0.05). The use of beta-blocker, ace-inhibitors, ejection fraction, and body mass index were significant determinants for the hemodynamic situation (heart rate, mean arterial pressure, pressure rate product) of the patient during the pre-induction period.

Conclusion

The oral administration of clonidine is the only significant predictor for the observed variation of norepinephrine levels during the preoperative period. Lack of significant dose responsiveness suggests that even a low dose of the drug can attenuate the preoperative stress response and thus is recommended in cardiovascular high risk patients.

Clonidine premedication decreases hemodynamic responses to pin head-holder application during craniotomy

The aim of this study was to compare hemodynamic responses to intubation and pin head-holder application in two groups of neurosurgical patients given oral clonidine (3 microg/kg) or oral temazepam (10-20 mg) 90 min before the induction of anesthesia. Fifty patients undergoing elective craniotomy were randomized to either group. Anesthesia was induced with i.v. propofol 1500 mg/h, fentanyl 4 microg/kg, vecuronium 0.15 mg/kg, and lidocaine 1.5 mg/kg and was maintained with propofol 6 mg x kg(-1) x h(-1). Mean arterial blood pressure (MAP) and heart rate were recorded before the induction of anesthesia and before and after intubation and application of the pin head holder. Interventions required to maintain hemodynamic stability were compared between groups. Preinduction sedation scores and MAP values were similar between groups. MAP was significantly lower (P = 0.031) in the clonidine group after pin head-holder application. Interventions to stabilize MAP were not significantly different between groups (P = 0.11). We conclude that clonidine is effective in reducing the MAP increase with pin head-holder application in patients undergoing craniotomy.

IMPLICATIONS

In this study, we investigated an approach to the prevention of increased blood pressure often seen during the early part of anesthesia for brain surgery. Oral clonidine was effective in reducing the mean arterial blood pressure increase resulting from pin head-holder application. Clonidine, a blood pressure-reducing drug, was given to 25 patients before anesthesia. Their blood pressure measurements were then compared with those of 25 patients not given clonidine.

Effects of intravenous and oral clonidine on hemodynamic and plasma-catecholamine response due to endotracheal intubation

STUDY OBJECTIVE

To investigate the effects of intravenous (IV) versus oral clonidine on alterations of heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), and plasma-catecholamines due to endotracheal intubation.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

University hospital surgery operating room.

PATIENTS

33 ASA physical status I patients were randomly assigned to either receive clonidine 3 micrograms/kg IV immediately prior to anesthesia induction, clonidine 4 micrograms/kg orally 90 minutes prior to anesthesia induction, or placebo.

INTERVENTIONS

Insertion of a 14 G cannula in a large cubital vein for the determination of plasma-catecholamines using local anesthesia. Insertion of a radial artery catheter for measuring blood pressure (BP) using local anesthesia. Transthoracic echocardiography determined CO.

MEASUREMENTS AND MAIN RESULTS

Heart rate, MAP, CO, and plasma-catecholamine concentrations were measured. Measurements were performed prior to induction, during intubation, and 10 minutes after intubation. During endotracheal intubation, MAP was significantly lower in the IV clonidine group compared with the placebo and the oral clonidine groups. Cardiac output was significantly lower in the IV clonidine group only. In contrast to the placebo group, norepinephrine plasma concentrations did not increase in either clonidine group. Significant alterations of epinephrine plasma concentrations due to intubation were not observed in either group. Hemodynamics after intubation were not impaired by clonidine treatment.

CONCLUSIONS

In conclusion, IV clonidine reduced stress response to endotracheal intubation compared with placebo. Oral clonidine at the dose used was less effective in blunting hemodynamic stress response than IV clonidine.

Control of post anaesthetic shivering with nefopam hydrochloride in mildly hypothermic patients after neurosurgery

Postoperative shivering may be prevented by maintaining normothermia intraoperatively or it may be treated using specific drugs. The aim of this study was to compare the efficacy of nefopam hydrochloride (nefopam) to that of clonidine and meperidine in patients undergoing elective neurosurgical procedures. Three groups of patients were included in the study. Patients in group A (60) received i.v., at random, 20 mg of nefopam, 50 mg of meperidine or 150 micrograms of clonidine in the immediate postoperative period. The incidence of shivering and the time at which shivering ceased were noted, along with central temperature and main haemodynamic changes. Group B (20) received i.v., at random, either 10 mg of nefopam or saline before awakening from anaesthesia. The effects of nefopam on central temperature, oxygen consumption (Vo2), carbon dioxide production (VcO2), basal metabolic rate (BMR) and energy expenditure (EE) were investigated. Group C (10) received i.v. 20 mg of nefopam during surgery: cerebrospinal fluid pressure (CSFP), cerebral perfusion pressure (CPP) and electroencephalogram (EEG) were monitored. In group A nefopam stopped shivering in 95% of patients when compared to meperidine and clonidine, which were effective in 32% and 40% of patients respectively. In group B, only 10% of patients receiving nefopam had postoperative shivering, Vo2, VcO2 and EE were significantly lower in patients treated with nefopam than those in the control group. No changes in CSFP, CPP or EEG were observed in group C. In conclusion, nefopam seems to be more effective than clonidine or meperidine in quickly suppressing shivering, without producing significant adverse reactions.