[Cardiovascular stress protection following anesthesia induction. Comparison of clonidine and esmolol]

Comparative Study Between Intravenous Clonidine and Preservative Free Intravenous Lignocaine in Attenuation of Pressor Response to Laryngoscopy and Endotracheal Intubation

Objectives

To compare the attenuation of pressor responses by intravenous clonidine and preservative-free lignocaine to laryngoscopy and endotracheal intubation.

Materials and Methods

A randomized, prospective, comparative, double-blinded study was conducted in 80 adult patients who were randomized into two groups of 40 each, group clonidine (Group C) and group lignocaine (Group L). Group C patients were given 2 µg/kg clonidine in 20 ml of normal saline as a slow infusion over 10 min prior to intubation. Group L patients were given 1.5 mg/kg of preservative-free 2% lignocaine in 20 ml of normal saline as a single-dose infusion over 3 min prior to intubation. Baseline vital and hemodynamic parameters were monitored during the perioperative period at 1-, 5-, and 10-min post-intubation.

Results

The attenuation of heart rate (HR) after intubation was much better with clonidine than lignocaine as there is statistically significant difference in the mean HR between the two groups at 1, 5, and 10 min after intubation with the HR significantly lesser in the Group C than the Group L at all times after intubation. Both clonidine and lignocaine were effective in attenuating systolic blood pressure response after intubation, but clonidine was more effective than lignocaine as systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) in the Group C remained much lower than the Group L and the difference between the two groups was statistically significant at all times after intubation.

Conclusion

Premedicating with a single slow infusion of 2 µg/kg i.v. clonidine has been proven to be effective in maintaining perioperative hemodynamic stability at 1, 5, and 10 min post-intubation than lignocaine.

Anesthetic Management of a Patient With Catecholaminergic Polymorphic Ventricular Tachycardia

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited arrhythmogenic disorder induced by adrenergic stress. Electrophysiologically, it is characterized by emotional stress- or exercise-induced bidirectional ventricular tachycardia that may result in cardiac arrest. Minimizing perioperative stress is critical as it can reduce fatal arrhythmias in patients with CPVT. Dexmedetomidine (DEX), a centrally acting sympatholytic anesthetic agent, was used in the successful intravenous (IV) moderate sedation of a 27-year-old female patient with CPVT, a history of cardiac events, and significant dental fear and anxiety scheduled to undergo mandibular left third molar extraction. Oral surgery was successfully performed under DEX-based IV sedation to reduce stress, and no arrhythmias were observed. IV sedation with DEX provided a sympatholytic effect with respiratory and cardiovascular stability in this patient with CPVT who underwent oral surgery.

Effectiveness of lidocaine/prilocaine cream on cardiovascular reactions from endotracheal intubation and cough events during recovery period of older patients under general anesthesia: prospective, randomized placebo-controlled study

BACKGROUND

Endotracheal intubation is known to pose significant physiological, pharmacokinetic, and dynamic changes and postoperative respiratory complications in patients under general anesthesia.

METHOD

An RCT trial was organized by the Third Affiliated Hospital at Sun Yat-sen University, China. Patients were eligible for inclusion in the trial if they were over 60 years old and had upper-abdominal surgery during the induction of anesthesia and had enrolled in endotracheal intubations. The primary end point included cardiovascular reactions during the induction of anesthesia and endotracheal intubations and cough events during the recovery period. In the test group, 2 g of lidocaine/prilocaine cream (and in the control group, 2 g of Vaseline) were laid over the surface of the tracheal tube cuff.

RESULTS

The systolic blood pressure (F value = 62.271, p < 0.001), diastolic blood pressure (F value = 150.875, p < 0.001), and heart rate (F value = 75.627, p < 0.001) of the test group were significantly lower than the control group. Cough events during the recovery period in the test group were better (spontaneous cough, χ² value = 10.591, p < 0.001; induced cough, χ² value =10.806, p < 0.001).

CONCLUSION

In older patients, coughing and cardiovascular reactions under anesthesia and endotracheal intubations were reduced, as a result of using lidocaine/prilocaine cream on the surface of the tracheal tube cuff.

TRIAL REGISTRATION

International Clinical Trials Network NCT02017392, 2013-12-16.

Effects of stellate ganglion block on cardiovascular reaction and heart rate variability in elderly patients during anesthesia induction and endotracheal intubation

STUDY OBJECTIVE

To investigate the effects of stellate ganglion block (SGB) on cardiovascular response and heart rate (HR) variability in elderly patients during anesthesia induction and endotracheal intubation.

DESIGN

A randomized, double-blinded, and placebo-controlled study.

SETTING

University-affiliated teaching hospital.

PARTICIPANTS

Eighty elderly patients (American Society of Anesthesiologists grades I and II) receiving elective surgery during general anesthesia.

INTERVENTIONS

Right stellate ganglion injection (SGB) was performed in all patients using 10 mL of 1% lidocaine or normal saline.

MEASUREMENTS

Systolic blood pressure (BP), diastolic BP, HR, and calculated rate pressure product. HR variability at the following time points: conscious status before induction (T0); immediately before intubation (T1); immediately after intubation (T2); and 1, 3, and 5 minutes postintubation (T3, T4, and T5).

MAIN RESULTS

No significant differences in BP and HR were observed between the 2 groups. Rate pressure product values significantly increased in the control group compared with baseline and SGB group values. Low-frequency power (LF) and LF/high-frequency power (HF) significantly increased, and HF and normalized units of HF significantly decreased in the control group compared with baseline values. LF, normalized units of LF, and LF/HF in the SGB group significantly decreased compared with those of the control group.

CONCLUSION

SGB protects the myocardium and effectively suppresses stress responses during anesthesia induction and tracheal intubation in elderly patients.

Comparison of bolus and continuous infusion of esmolol on hemodynamic response to laryngoscopy, endotracheal intubation and sternotomy in coronary artery bypass graft

BACKGROUND AND OBJECTIVE

The aim of this randomized, prospective and double blinded study is to investigate effects of different esmolol use on hemodynamic response of laryngoscopy, endotracheal intubation and sternotomy in coronary artery bypass graft surgery.

METHODS

After approval of local ethics committee and patients' written informed consent, 45 patients were randomized into three groups equally. In Infusion Group; from 10 min before intubation up to 5th minute after sternotomy, 0.5mg/kg/min esmolol infusion, in Bolus Group; 2 min before intubation and sternotomy 1.5mg/kg esmolol IV bolus and in Control Group; %0.9 NaCl was administered. All demographic parameters were recorded. Heart rate and blood pressure were recorded before infusion up to anesthesia induction in every minute, during endotracheal intubation, every minute for 10 minutes after endotracheal intubation and before, during and after sternotomy at first and fifth minutes.

RESULTS

While area under curve (AUC) (SAP×time) was being found more in Group B and C than Group I, AUC (SAP×Tint and Tst) and AUC (SAP×T2) was found more in Group B and C than Group I (p<0.05). Moreover AUC (HR×Tst) was found less in Group B than Group C but no significant difference was found between Group B and Group I.

CONCLUSION

This study highlights that esmolol infusion is more effective than esmolol bolus administration on controlling systolic arterial pressure during endotracheal intubation and sternotomy in CABG surgery.

[Quality of premedication and patient satisfaction after premedication with midazolam, clonidine or placebo : Randomized double-blind study with age-adjusted dosage]

BACKGROUND

Premedication aims at alleviating preoperative anxiety and nervousness and also at minimizing adverse effects. To our knowledge there is no study comparing efficacy and patient satisfaction of different premedications in age-adjusted dosage.

METHODS

In 139 patients anxiety, sedation and adverse effects were measured at 6 consecutive perioperative time points after administration of midazolam, clonidine or a placebo.

RESULTS

Midazolam showed the strongest sedative and anxiolytic effects, clonidine less and placebo none. Clonidine and midazolam reduced the risk of postoperative nausea and vomiting (PONV). Midazolam showed minimal adverse effects and the best patient satisfaction.

CONCLUSION

Midazolam was the most anxiolytic, sedative and favored premedication with the least adverse effects. Most patients would choose midazolam next time.

Effects of esmolol, lidocaine and fentanyl on haemodynamic responses to endotracheal intubation: a comparative study

BACKGROUND AND OBJECTIVE

Predicting the haemodynamic changes that may result in myocardial ischaemia for patients undergoing laryngoscopy and tracheal intubation will help to avoid events that trigger ischaemia and allow immediate treatment. The objective of this study was to compare the effects of esmolol with those of lidocaine (lignocaine) and fentanyl on prevention of tachycardia and hypertension caused by endotracheal intubation.

METHODS

This was a prospective, randomised, double-blind study. The study was conducted at the Adnan Menderes University Hospital in Aydin, Turkey and involved 120 patients of American Society of Anesthesiologists physical status I or II aged 20-50 years. The patients were randomised into four equal groups. The control group (group C) received dextrose 5% 5 mL, the esmolol group (group E) received esmolol 1.5 mg/kg, the fentanyl group (group F) received fentanyl 1 microg/kg and the lidocaine group (group L) received lidocaine 1.5 mg/kg 2 minutes before endotracheal intubation. Heart rate (HR), mean arterial pressure (MAP) and rate-pressure product (RPP) were recorded before and after induction of anaesthesia, immediately after intubation, and 1, 3, 5, 7 and 10 minutes after intubation.

RESULTS

Compared with control, HR decreased significantly in group E after induction, immediately after intubation and 1 minute after intubation (p < 0.0083). In group F there was an increase in MAP immediately after intubation, but the increase was less than in other groups. Compared with control, RPP decreased significantly in groups E and F after induction, immediately after intubation and 1 minute after intubation (p < 0.0083). RPP was significantly lower in group E than in controls and group L 3 minutes after intubation (p < 0.0083), and it was significantly lower in group F than in controls 10 minutes after intubation (p < 0.0083).

CONCLUSION

It can be concluded that administration of esmolol 1.5 mg/kg 2 minutes before intubation prevents tachycardia and an increase in RPP caused by laryngoscopy and tracheal intubation, and can be beneficial when administered before laryngoscopy and tracheal intubation in patients with tachycardia.

The Effects of Esmolol and Dexmedetomidine on Myocardial Oxygen Consumption During Sympathetic Stimulation in Dogs

OBJECTIVE

The purpose of this study was to compare the potential of the beta(1)-adrenergic receptor blocker esmolol and the alpha(2)-adrenergic receptor agonist dexmedetomidine to suppress the cardiovascular and neuroendocrine response to a sympathetic stimulus.

DESIGN

Experimental study.

SETTING

Laboratory of university.

PARTICIPANTS

Eleven anesthetized dogs.

INTERVENTIONS

Catheters for arterial and coronary venous blood sampling and calculation of myocardial oxygen consumption were inserted. Pressure sensors were placed in the aorta, left ventricle, and a carotid artery. Flow probes were placed around the aortic root and around the left anterior descending coronary artery. Esmolol was infused (loading dose of 1 mg/kg, infusion of 0.3 mg/kg/h), and the adequacy of beta-blockade was checked. Thirty minutes after stopping esmolol, dexmedetomidine infusion was started (loading dose of 1 microg/kg, infusion of 1.5 microg/kg/min). Occlusion of both carotid arteries was used as a sympathetic stimulus before and during infusion of esmolol and before and during infusion of dexmedetomidine.

MEASUREMENTS AND MAIN RESULTS

The variables were measured just before and during sympathetic stimulation, and changes were calculated. Both drugs suppressed the increase in dPdT(max). Dexmedetomidine suppressed the increase in plasma norepinephrine and the increase in systemic vascular resistance (dexmedetomidine 4% +/- 4% and esmolol 25% +/- 19% increase, p = 0.02). Esmolol attenuated the heart rate response (esmolol 2% +/- 2% and dexmedetomidine 20% +/- 18% increase, p = 0.02). However, dexmedetomidine decreased baseline heart rate more than esmolol; therefore, the absolute maximal heart rate during sympathetic stimulation was lower in the presence of dexmedetomidine (dexmedetomidine 119 +/- 14 and esmolol 141 +/- 15 beats/min, p = 0.01). Neither drug suppressed the increase in myocardial oxygen consumption.

CONCLUSIONS

Both esmolol and dexmedetomidine have the potential to suppress some of the cardiovascular and neuroendocrine changes to a sympathetic stimulus but neither drug abolished the increase in myocardial oxygen consumption.

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.