Dose-response effects of intravenous clonidine on stress response during induction of anesthesia in coronary artery bypass graft patients

Oral Clonidine vs Oral Pregabalin Premedication to Attenuate Pressor Response to Direct Laryngoscopy in Patients Undergoing Laparoscopic Cholecystectomy: A Randomized Double Blind Study

INTRODUCTION

Direct laryngoscopy and tracheal intubation has adverse effects like tachycardia, hypertension, myocardial ischemia and cerebral haemorrhage. There are several studies on various pharmacological agents to attenuate this response.

AIM

This study was designed to compare efficacy and safety of oral clonidine and oral pregabalin premedication to attenuate stress response in patients undergoing laparoscopic cholecystectomy.

MATERIALS AND METHODS

Total 80 patients of ASA grade I and II, aged between 20-60 years of both sexes scheduled for elective laparoscopic cholecystectomy were included in the study. All the patients were randomized into two groups. Group A received oral clonidine 0.3mg and group B received oral pregabalin 150mg, 60 minutes before surgery. Anaesthesia technique was standardized. Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), mean arterial pressure (MAP) and heart rate were recorded preoperatively, after premedication, immediately after intubation, then at 1 min, 3 min, 5 min, 10 min and 15 min after intubation. Level of sedation, postoperative pain scores and any adverse effects were also noted and compared.

RESULTS

Oral clonidine 0.3mg as well as oral pregabalin 150mg were effective in blunting haemodynamic stress response to laryngoscopy and tracheal intubation. Clonidine was found to be better than pregabalin in lowering of systolic blood pressure, diastolic blood pressure, mean arterial pressure and heart rate changes associated with laryngoscopy. We also found that bradycardia was common with both the drugs, more so in clonidine group. Post-operative analgesia was better in pregabalin group as compared to clonidine group. Both the drugs cause sedation, but it was more with the use of pregabalin.

CONCLUSION

Both the drugs can be used as an effective premedicant to attenuate the sympathetic response to laryngoscopy and tracheal intubation without much side effects and the added advantage of intraoperative and postoperative analgesia.

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 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.

Effect of nalbuphine and pentazocine on attenuation of hemodynamic changes during laryngoscopy and endotracheal intubation: A clinical study

Background:

Narcotic drugs have been used to attenuate laryngoscopy and intubation induced circulatory responses, but are not always available due to tough narcotics laws. Nalbuphine a synthetic opioid, free from restrictions has been in use for post-operative pain relief. Hence, we decided to compare nalbuphine and pentazocine for attenuation of hemodynamic effects during larygoscopy and endotracheal intubation in a randomized, double-blind clinical study.

Materials and Methods:

A total of 60 patients (ASA I and II) of either sex, between 18 years and 50 years were given either nalbuphine 0.2 mg/kg (group N, n = 30) or pentazocine 0.5 mg/kg (group P, n = 30) 5 min before induction of general anesthesia. After, induction with thiopentone and endotracheal intubation with succinylcholine balanced anesthesia was maintained with O₂:N₂O, 0.2% halothane and non-depolarizing relaxants for surgical duration. Changes in heart rate (HR), systolic blood pressure (SBP), diastolic pressure, mean arterial pressure, and rate pressure product calculated by HR × SBP were recorded at various time intervals.

Results:

A non-significant fall (P > 0.05) up to 3 min and thereafter a significant rise (P < 0.05) in all the parameters were observed throughout the remaining study period with nalbuphine, whereas a continuous and significant (P < 0.05) rise in these parameters were observed with pentazocine. Maximum rise in both the group was observed immediately after larygoscopy and intubation and these started to return toward the basal values at the end of the study period, but remained above the initial values. (pentazocine > nalbuphine P = <0.01).

Conclusion:

Nalbuphine effectively reduces the tachycardia, hypertension, and cardiac workload associated with laryngoscopy and endotracheal intubation.

Low-dose intramuscular dexmedetomidine as premedication: a randomized controlled trial

BACKGROUND

Dexmedetomidine-induced bradycardia or hypotension has recently attracted considerable attention because of potentially grave consequences, including sinus arrest and refractory cardiogenic shock. A route other than intravenous injection or a low dose may help minimize cardiovascular risks associated with dexmedetomidine. However, few studies have addressed the clinical effects of low-dose intramuscular dexmedetomidine as premedication.

MATERIAL AND METHODS

Forty American Society of Anesthesiologists physical status I adult patients undergoing suspension laryngoscopic surgery were randomized to receive intramuscular dexmedetomidine (1 µg·kg-1) or midazolam (0.02 mg·kg-1) 30 minutes prior to anaesthesia induction. The sedative, hemodynamic, and adjuvant anaesthetic effects of both premedications were assessed.

RESULTS

The levels of sedation (Observer's Assessment of Alertness/Sedation scales) and anxiety (visual analog score) at pre-induction, and the times to eye-opening and extubation, were not different between the groups. The heart rate response following tracheal intubation and extubation, and mean arterial pressure responses after extubation, were attenuated in the dexmedetomidine group compared to the midazolam group. No bradycardia or hypotension was noted in any patients. Propofol target concentrations at intubation and at start and completion of surgery were decreased in the dexmedetomidine group, whereas no difference in respective remifentanil levels was detected.

CONCLUSIONS

This study provides further evidence that dexmedetomidine premedication in low dose (1 μg·kg-1) by intramuscular route can induce preoperative sedation and adjuvant anaesthetic effects without clinically significant bradycardia or hypotension.

Comparison of clonidine and midazolam premedication before endoscopic sinus surgery: results of clinical trial

OBJECTIVES

Premedication with clonidine has been found to reduce the bleeding during endoscopic sinus surgery (ESS), therefore lowering the risk of surgical complications. Premedication is an essential part of pre-surgical care and can potentially affect magnitude of systemic stress response to a surgical procedure. The aim of this study was to compare the efficacy of premedication with clonidine and midazolam in patients undergoing sinus surgery.

METHODS

Forty-four patients undergoing ESS for chronic sinusitis and polyp removal were enrolled and randomly assigned to receive either oral clonidine or midazolam as a premedication before receiving propofol/remifentanil total intravenous anesthesia. The effect of this premedication choice on anesthetic requirements, intraoperative hemodynamic profile, preoperative anxiety and sedation as well as postoperative pain and shivering were examined in each premedication group.

RESULTS

Total intraoperative remifentanil requirement was lower in the clonidine group as compared to the midazolam group 503.2±147.0 µg vs. 784.5±283.8 µg, respectively (P<0.001). There was no difference between groups in required induction dose of propofol, level of preoperative anxiety, level of sedation and postoperative shivering. Intraoperative systemic blood pressure and heart rate response had a more favorable profile in patients premedicated with clonidine. Postoperative pain assessed by visual analogue scale for pain was lower in the clonidine group compared with to the midazolam premedication group.

CONCLUSION

Premedication with clonidine provides better attenuation of hemodynamic response and reduction of intraoperative remifentanil requirements in patients undergoing ESS. Postoperative pain seems to be better controlled after clonidine premedication as well.

The dose-related effects of dexmedetomidine on renal functions and serum neutrophil gelatinase-associated lipocalin values after coronary artery bypass grafting: a randomized, triple-blind, placebo-controlled study

OBJECTIVES

Acute kidney failure after coronary artery bypass grafting (CABG) is a serious complication that increases morbidity and mortality rates. Early detection and prevention of this complication are very important. A novel biomarker named neutrophil gelatinase-associated lipocalin (NGAL) can play an important role in early diagnosis of acute kidney injury. Recent studies on the favourable effects of Dexmedetomidine on cardiac surgery have been published. The aim of this study is to investigate whether there is a dose-dependent positive effect of Dexmedetomidine on neutrophil gelatinase-associated lipocalin levels and renal functions when used after CABG.

METHODS

Our randomized, triple-blinded, placebo-controlled study was conducted among 295 patients scheduled for CABG surgery between August 2009 and March 2011 in a tertiary cardiac and vascular surgery clinic. A total of 90 consecutive patients who met inclusion criteria were randomized and divided into three groups. The first group received a placebo. The second and the third groups received 4 and 8 µg/cc concentration of the Dexmedetomidine infusion, respectively. Infusion rates were regulated to obtain sedation with a Ramsey sedation score of 2 or 3. Patients were regrouped according to the total Dexmedetomidine dose. Statistical analyses of variables including serum neutrophil gelatinase-associated lipocalin values and conventional renal function tests were made for all six possibilities before the blind was broken.

RESULTS

Results of conventional renal function tests were not significantly different. However, neutrophil gelatinase-associated lipocalin levels for the first postoperative day for placebo, low-dose and high-dose Dexmedetomidine groups were 176.8 ± 145.9, 97.7 ± 63.4 and 67.3 ± 10.9 ng/ml, respectively. These values were significantly different among the groups (P <0.001).

CONCLUSIONS

In our study, we found that Dexmedetomidine infusion for sedation after CABG under cardiopulmonary bypass can be useful in the prevention of kidney injury. Conventional renal function tests, including blood urea nitrogen, serum creatinine, urine output and creatinine clearance rate measurements typically may not detect the development of acute kidney dysfunction in the first 48-h postoperative period. Differences were detected in renal function in the early postoperative period and the development of acute kidney injury, as determined by measurements of blood NGAL levels, was significant and dose-dependent.

Comparison of the efficacy of dexmedetomidine with that of esmolol in attenuating laryngoscopic and intubation response after rapid sequence induction

CONTEXT

Laryngoscopy and tracheal intubation produce sympathetic overdrive by catecholamine release resulting in hypertension and tachycardia. Various agents are being tried to combat the intubation response over years.

AIMS

This study is aimed at comparing dexmedetomidine which is a highly selective alpha-2 agonist with an ultra-short acting beta blocker, esmolol to see which among the two is better in attenuating the hemodynamic response to laryngoscopy and tracheal intubation.

SETTINGS AND DESIGN

This was a prospective randomized double-blind control study.

SUBJECTS AND METHODS

Sixty patients scheduled for general anesthesia were divided into two groups, D and E with 30 patients in each group. Group-D patients received dexmedetomidine 0.5 mcg/kg and Group-E patients received esmolol 0.5 mg/kg as intravenous premedication over 5 min before a rapid sequence induction and tracheal intubation. Systolic, diastolic and mean arterial pressures along with heart rate were measured using invasive arterial line at various time points. The percentage change of hemodynamic parameters at those time points from the baseline was compared between the groups.

STATISTICAL ANALYSIS USED

Descriptive and inferential statistical methods were used to analyze the data.

RESULTS

The percentage change of all hemodynamic parameters from base line were less in the dexmedetomidine group than in esmolol group at all-time points of measurement. However, a statistically significant difference was observed often at the time points within 1 min after tracheal intubation.

CONCLUSIONS

Dexmedetomidine is superior to esmolol in attenuating the hemodynamic response to laryngoscopy and tracheal intubation.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

The effectiveness of intramuscular dexmedetomidine on hemodynamic responses during tracheal intubation and anesthesia induction of hypertensive patients: a randomized, double-blind, placebo-controlled study

BACKGROUND

Hypertensive patients are at risk for increased hemodynamic response to tracheal intubation. Sympatholytic drugs administered during the preinduction period may prevent adverse events.

OBJECTIVE

We assessed the effectiveness of a single preinduction IM bolus dose of dexmedetomidine (DMED) 2.5 μg/kg in attenuating hemodynamic responses to tracheal intubation and rapid-sequence anesthesia induction in hypertensive patients treated with angiotensin-converting enzyme inhibitors.

METHODS

Adult patients (American Society of Anesthesiologists classification II and III) with essential hypertension, scheduled for elective abdominal or gynecologic surgery, were enrolled in this randomized, double-blind, placebo-controlled study. Patients were assigned to i of 2 groups: the DMED group received IM DMED 2.5 μg/kg and the placebo group received IM saline 0.9% 45 to 60 minutes before induction of anesthesia. General anesthesia was induced with thiopental, fentanyl, and vecuronium and maintained with a sevoflurane-nitrous oxide-oxygen mixture. Hemodynamic values were recorded before (baseline) and after anesthesia induction, before endotracheal intubation, and 1, 3, and 5 minutes after intubation. The patients were monitored for hypotension (systolic arterial pressure [SAP] decreased ≥25% from baseline or to <90 mm Hg) or bradycardia (heart rate [HR] decreased ≥25% from baseline or to <50 beats/min).

RESULTS

Nine hundred sixty patients were assessed for enrollment during a 6-month period. Sixty patients (49 women, 11 men; mean [SD] age, 59.16 [8.39] years) were eligible for the study. There were no significant differences in baseline hemodynamic values between the groups. SAP and diastolic arterial pressure (DAP) before anesthesia induction, 1 and 3 minutes after intubation, and DAP 1 minute after intubation were significantly lower in the DMED group than in the placebo group (all, P < 0.05). There were no significant between-group differences in SAP or DAP 5 minutes after intubation. HR before anesthesia induction, before intubation, and 1, 3, and 5 minutes after intubation were lower in the DMED group than in the control group (all, P < 0.05). In the DMED group, SAP after intubation, DAP before intubation, 3 and 5 minutes after intubation, HR before induction, before intubation, and 3 and 5 minutes after intubation were significantly decreased compared with baseline values (all, P < 0.05). In the control group, SAP at all times, DAP before intubation, 1, 3, and 5 minutes after intubation, HR before intubation, and 3 and 5 minutes after intubation were significantly decreased compared with baseline values (all, P < 0.05). Hypotension and bradycardia were observed together in 3 patients, and hypotension alone was observed in 1 patient 3 minutes after intubation in the DMED group; hypotension was observed in 1 patient at 3 minutes after intubation in the control group.

CONCLUSION

The results of this study suggest that IM DMED 2.5 μg/kg administered 45 to 60 minutes before anesthesia induction attenuated, but did not completely prevent, hemodynamic responses to tracheal intubation in these patients with essential hypertension.

Oral clonidine pretreatment prior to venous cannulation

Clonidine is a preferential alpha-2 agonist drug that has been used for over 35 years to treat hypertension. Recently, it has also been used as a preoperative medication and as a sedative/anxiolytic drug. This randomized, double-blind, placebo-controlled crossover clinical trial characterized the effects of oral clonidine pretreatment on intravenous catheter placement in 13 patients. Parameters measured included the bispectral index (BIS), Observer's Assessment of Alertness/Sedation Scale (OAA/S), frontal temporal electromyogram (EMG), 30-Second Blink Count (Blink), Digit Symbol Substitution Test (DSST), State Anxiety Inventory (SAI), fingertip versus forearm skin temperatures, and multiple questionnaires. Oral clonidine significantly decreased SAI scores, OAA/S, EMG, and Blink, but did not cause statistically significant BIS or DSST reductions. Subjects preferred oral clonidine pretreatment prior to venipuncture compared to placebo. Questionnaires also indicated that clonidine provided minimal sedation, considerable anxiolysis, and some analgesia. Fingertip versus forearm skin temperature differentials were decreased. Reduced fingertip versus forearm temperature differentials suggest increased peripheral cutaneous blood flow prior to venous cannulation. Oral clonidine pretreatment not only helped control patient anxiety and pain but also provided cardiovascular stability.

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.

Haemodynamic effects of intravenous clonidine on propofol or thiopental induction

The study evaluated the effects of premedication with intravenous clonidine on thiopental or propofol requirements for induction and haemodynamic changes associated with both induction and endotracheal intubation. Clonidine administered intravenously before induction of anaesthesia reduced propofol or thiopental requirements. The association of clonidine and propofol caused, after injection of the induction drug, a decrease in mean arterial pressure which was significantly greater than with thiopental. Moreover, a major haemodynamic stability was registered before and after laryngoscopy in the clonidine-thiopental group. These findings might contraindicate the clonidine-propofol combination in patients with cardiovascular disease.

Can clonidine, enoximone, and enalaprilat help to protect the myocardium against ischaemia in cardiac surgery?

OBJECTIVE

To evaluate whether clonidine, enoximone, and enalaprilat reduce ischaemia-related myocardial cell damage in cardiac surgery.

DESIGN

Prospective randomised controlled trial.

SETTING

Clinical investigation in a cardiac anaesthesia department of a university hospital.

PATIENTS

88 consecutive patients undergoing coronary artery bypass surgery.

INTERVENTIONS

After induction of anaesthesia patients continuously received the alpha 2 agonist clonidine (group 1, n = 22), the phosphodiesterase (PDE) III inhibitor enoximone (group 2, n = 22), the angiotensin converting enzyme (ACE) inhibitor enalaprilat (group 3, n = 22), or saline solution as placebo (control group, n = 22). The infusion was stopped immediately before the start of cardiopulmonary bypass.

MAIN OUTCOME MEASURES

The ST segment was analysed and the activity of creatine kinase isoenzyme MB (CKMB), cardiac troponin T (TnT), and the BB isoenzyme of glycogen phosphorylase (GPBB) were measured before the start of infusion (baseline), after weaning from cardiopulmonary bypass (CPB), at the end of surgery, 5 h after CPB, and on the morning of the first and third postoperative days.

RESULTS

Biometric data and time of cross-clamping were not significantly different in the four groups. Changes in the ST segment indicating ischaemia were least common in the enalaprilat group (P < 0.05). Postoperatively, CKMB activity was significantly higher in the clonidine and the control groups. Both new markers of myocardial cell damage increased more after CPB and postoperatively in the control patients (TnT peak: (mean (SD)) 3.99 (0.35) microgram/1; GPBB peak: 82 (15) ng/ml) and the clonidine-treated group (TnT peak: 3.80 (0.3) microgram/1; GPBB peak: 85 (14) ng/ml). Enalaprilat-treated patients showed the smallest overall changes in standard (CKMB) and new serological markers of myocardial ischaemia (TnT peak: 0.71 (0.1) microgram/1; GPBB peak: 44 (14) ng/ml).

CONCLUSIONS

In patients treated with enalaprilat before CPB, both new, more sensitive markers of ischaemic myocardial tissue damage increased significantly less than in an untreated control group. Those treated with enoximone also had lower plasma concentration of TnT and GPBB than the control group, whereas clonidine did not reduce the concentration of these markers of myocardial ischaemia. Pharmacological interventions, such as the continuous infusion of the ACE inhibitor enalaprilat, before start of CPB may help to protect the heart against ischaemia/reperfusion injury.