Effect of buprenorphine on the cardiovascular response to tracheal intubation

Effects of epidural and intravenous buprenorphine on halothane minimum alveolar anesthetic concentration and hemodynamic responses

There is limited information regarding the effects of epidural or intravenous (i.v.) buprenorphine on minimum alveolar anesthetic concentration (MAC) of volatile anesthetic and hemodynamic responses to tracheal intubation and surgical incision. This study was conducted to find the effects of i.v. and epidural buprenorphine required for postoperative pain relief on halothane MAC and hemodynamic responses to tracheal intubation and surgical incision in 126 female patients. Patients were randomly assigned to the four groups: Group I received i.v. and epidural saline as a control; Group II was given buprenorphine 4 micrograms/kg i.v.; and Groups III and IV received buprenorphine 2 and 4 micrograms/kg epidurally, respectively. Groups II-IV were divided into the two subgroups according to the timing of administration, either at induction of anesthesia in the operating room (OR) (OR group) or 90 min before anesthetic induction in the ward (Ward group). Anesthesia was induced with only halothane in oxygen, and the trachea was intubated without other drugs. Halothane MAC was determined by logistic regression analysis and the Dixon up-and-down method. Halothane MAC in the seven study groups was as follows: 0.75% +/- 0.05% (mean +/- SE) in Group I; 0.49% +/- 0.03% and 0.59% +/- 0.04%, respectively, in Groups II OR and Ward; 0.65% +/- 0.003% and 0.49% +/- 0.07%, respectively, in Groups III OR and Ward; and 0.51% +/- 0.07% and 0.37% +/- 0.02%, respectively, in Groups IV OR and Ward. Halothane MAC decreased significantly (P < 0.05) in groups that received buprenorphine except Group III-OR compared with Group I. Systolic blood pressure did not change significantly in Groups II-OR and IV-OR after tracheal intubation and in Group III-Ward and IV-Ward after surgical incision but increased significantly (P < 0.05) in the remaining groups in response to noxious stimuli. Heart rate responses to tracheal intubation and surgical incision were similar to those in systolic blood pressure. These results indicate that preanesthetic administration of epidural or IV buprenorphine required for postoperative analgesia reduces halothane MAC and attenuates hemodynamic responses to tracheal intubation and surgical incision according to the dose, route, and timing of administration.

Esmolol blunts the haemodynamic responses to tracheal intubation in treated hypertensive patients

PURPOSE

To compare the ability of different bolus doses of esmolol to blunt the haemodynamic effects of laryngoscopy and tracheal intubation in treated hypertensive patients.

METHODS

In this randomised, double-blind placebo controlled study, 45 ASA II patients, treated for essential hypertension with drugs other than beta blockers, were divided into three groups of 15 patients each. Patients in different groups either received 20 ml normal saline (Group P), or 100 mg esmolol (Group E100) or 200 mg esmolol (Group E200) as a single bolus intravenous dose before laryngoscopy and intubation. Systolic, diastolic and mean arterial pressure and heart rate were monitored for up to 10 min following intubation and were compared with respective basal readings as well as across groups.

RESULTS

Esmolol alone reduced systolic arterial pressure (P < 0.01 in Group E100 and P < 0.001 in Group E200) and heart rate (P < 0.001). Though there was an increase in arterial pressure and heart rate in the control group, esmolol 100 mg maintained arterial pressure and heart rate at levels comparable to basal values throughout the study (P > 0.05). Patients receiving esmolol 200 mg had lower values (P < 0.001) than their basal readings during most of the post-intubation study period.

CONCLUSION

Esmolol 100 mg given as bolus, is effective as well as safe in blunting the haemodynamic responses to laryngoscopy and tracheal intubation in treated hypertensive patients.

The effect of increasing the dose of buprenorphine on the haemodynamic response associated with tracheal intubation

The effect of buprenorphine on the haemodynamic response to tracheal intubation was studied at two dose levels, 2.5 micrograms.kg-1 and 5 micrograms.kg-1, in a placebo-controlled double-blind trial in 75 patients undergoing laparoscopic cholecystectomy. The study drugs were administered intravenously 8 min before induction of anaesthesia with thiopentone 5 mg.kg-1 and vecuronium 0.1 mg/kg-1. Buprenorphine 2.5 micrograms.kg-1 caused 50% attenuation of the blood pressure response whereas 5 micrograms/kg-1 caused 70% attenuation compared to the saline placebo. The maximum increase in heart rate was 14% of the control value after 2.5 micrograms.kg-1 and 11% after 5 micrograms/kg-1 of buprenorphine. A significant difference in heart rate was also observed between the two buprenorphine groups at 5 and 10 min after intubation. Blood pressure and heart rate both showed a significant fall from baseline values 10 min after intubation in both buprenorphine groups, with the changes being greater in the 5 micrograms.kg-1 group. We recommend the use of 2.5 micrograms.kg-1 buprenorphine for attenuation of the hypertensive response to intubation in major abdominal surgery.

[Consequences and prevention methods of hemodynamic changes during laryngoscopy and intratracheal intubation]

In patients ranked ASA 1, laryngoscopy and intubation lead to an average increase in blood pressure of 40 to 50%, and a 20% increase in heart rate. These changes, which are greatest one minute after intubation, last for 5 to 10 min. They are due to sympathetic and adrenal stimulation, which may also result in some arrhythmias. About half the patient with coronary artery disease experience episodes of myocardial ischaemia during intubation when no specific prevention is undertaken. Among the different means available for this, narcotics seem to have a reliable and constant effect, but they may be responsible for postoperative respiratory depression. The protective effect of fentanyl starts at 2 micrograms.kg-1, and is at a maximum at 8 micrograms.kg-1. Lidocaine is the drug used most. Recent studies have questioned its efficacy. In clinical practice, it is particularly effective in preventing the pressor response to tracheal intubation, whatever its route of administration (intravenous or intratracheal), but not the increase in heart rate. Beta blockers with bradycardic, antihypertensive, antiarrhythmic and antiischaemic properties, have been advocated. As opposed to lidocaine, these agents are more effective in preventing the changes in heart rate than the pressor response. Because of their depressor effect on the myocardium, their place still remains to be defined, especially in the cardiac risk patient. Short-acting beta blockers should be preferred. Nitroglycerin is specifically indicated in coronary artery disease. Other agents, such as clonidine or calcium blockers, seem to be less effective or less convenient in preventing the haemodynamic alterations. In clinical practice, prevention will first rely on a sufficient dose of narcotics. In some cases, nitroglycerin or beta blockers may be used so as to decrease the doses of narcotics, without altering their efficacy; however, the risk of hypotension should be constantly borne in mind. If preventing measures have not been taken, short-acting antihypertensive agents (beta blockers, calcium blockers) should be used in patients who develop major hypertension during laryngoscopy and intubation.

Effects of diazoxide on the cardiovascular response to tracheal intubation

The efficacy of 2 or 3 mg/kg diazoxide given 2.5 min before laryngoscopy in attenuating the cardiovascular responses to laryngoscopy and intubation was studied in 30 patients undergoing elective surgery. Data were compared with those from 10 control patients receiving saline. Anaesthesia was induced using 5 mg/kg thiopentone given intravenously and tracheal intubation was facilitated with 0.2 mg/kg vecuronium bromide. Patients receiving saline showed a significant increase in mean arterial pressure and rate-pressure product associated with tracheal intubation. The increases following tracheal intubation were significantly reduced (P less than 0.05) in diazoxide-treated patients compared with those in the control group, but there were no significant differences in heart rate following tracheal intubation among the three groups. Data suggest that diazoxide can be used as a supplement during induction of anaesthesia to attenuate the hypertensive response associated with laryngoscopy and tracheal intubation.

[Effects of urapidil on the cardiovascular response to intratracheal intubation]

The effects of urapidil on the haemodynamic response to endotracheal intubation were compared to that of placebo in two groups of 25 patients scheduled for general surgery. Normal saline solution or 0.4 mg.kg-1 urapidil were injected 3 min before induction of anaesthesia with 3 micrograms.kg-1 fentanyl, 0.3 mg.kg-1 etomidate and 0.1 mg.kg-1 vecuronium. Blood pressure (Pasys, Padia, Pa) and heart rate were measured continuously by servoplethysmomanometry before giving the test drug (T0), at the time when the lowest blood pressure was recorded during the three minute period between giving the drug and induction (T1), at the time when the lowest blood pressure was recorded during the three minute period between induction and endotracheal intubation (T2), at the time when the highest blood pressure was recorded immediately after intubation (T3), three minutes after intubation (T4), five minutes after intubation (T5), and at the time when the lowest blood pressure was recorded after surgery had been started (T6). It was planned to give a 25 mg urapidil dose to any patient, from either group, who had a Pasys greater than 200 mmHg for more than 60 sec. Giving urapidil lowered Pasys (T1) by 16%, whilst heart rate increased by 12%. The blood pressure peak due to endotracheal intubation was lower in those patients who had been given urapidil than in the placebo group (T3; p less than 0.05). Six patients in the latter group required the 25 mg urapidil dose, versus 2 in the urapidil group. The preventive effects of urapidil seem to be similar to those obtained with other antihypertensive agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of prostaglandin E1 on the cardiovascular response to tracheal intubation

STUDY OBJECTIVE

To evaluate the efficacy of prostaglandin E1 in attenuating the hypertensive response to laryngoscopy and intubation.

DESIGN

Controlled, comparative, and randomized study.

SETTING

Induction of anesthesia for elective surgery at a university hospital.

PATIENTS

Thirty normotensive patients (ASA physical status I) undergoing elective surgery divided into three groups. Each group consisted of ten patients.

INTERVENTIONS

Anesthesia was induced with thiopental sodium 5 mg/kg intravenously, and tracheal intubation was facilitated with vecuronium 0.2 mg/kg. Either 0.3 micrograms/kg of prostaglandin E1, 0.6 micrograms/kg of prostaglandin E1, or saline (control) was injected 15 seconds before starting direct laryngoscopy (within 30 seconds), which was attempted 2 minutes after administration of thiopental sodium and vecuronium.

MEASUREMENTS AND MAIN RESULTS

Patients receiving saline showed a significant increase in mean arterial pressure and rate-pressure product associated with tracheal intubation. These increases following tracheal intubation were significantly less in prostaglandin E1-treated patients than in the control group (p less than 0.05).

CONCLUSIONS

A single rapid intravenous administration of prostaglandin E1 is a practical pharmacologic and safe method to attenuate the hypertensive response to tracheal intubation. The use of 0.6 micrograms/kg of prostaglandin E1 as a supplement during induction is recommended for reducing the pressor response to intubation on the basis of rate-pressure product and mean arterial pressure following intubation as an index.

The effect of diltiazem on the cardiovascular response to tracheal intubation

The efficacy of diltiazem in the attenuation of the cardiovascular response to laryngoscopy and tracheal intubation was studied in patients who received 0.2 or 0.3 mg/kg diltiazem 60 seconds before the start of laryngoscopy. These data were compared with a control group who received saline. Each group consisted of 10 patients who had elective surgery. Patients who received saline showed a significant increase in mean arterial pressure and rate pressure product associated with tracheal intubation. These increases after tracheal intubation were reduced in diltiazem-treated patients compared with those of the control group (p less than 0.05). The data suggest that a bolus injection of diltiazem is a simple, practical and effective method to attenuate the hypertensive response to laryngoscopy and tracheal intubation.