A comparison of fentanyl, esmolol, and their combination for blunting the haemodynamic responses during rapid-sequence induction

Effectiveness of the oral Clonidine as a pre-anesthetic medicine for thyroidectomy surgery; A randomized clinical trial

Introduction

Hemodynamic disturbance is a common problem in patients undergoing thyroid surgery. It may be due to episodic increases in thyroid hormones (thyroid storm) or stimulation of the carotid sinus baroreflex. The aim of the present study was to investigate effectiveness of the pre-operative oral Clonidine on reducing these hemodynamic changes during total thyroidectomy surgery.

Methods

In a prospective, randomized, double-blind study, 80 patients scheduled for elective total thyroidectomy were randomized to receive either 0.2 mg Clonidine (n=40) or a matched placebo (n=40) orally sixty minutes before entering the operating room. Hemodynamic variables, the duration of surgery, estimated amount of blood loss and the dose of administered remifentanil were recorded for further analysis.

Results

Oral Clonidine was found to be significantly better in maintaining stable hemodynamics compared to the control group. Also, In the Clonidine group, the estimated amount of blood loss (110.4±10 ml vs. 182.2±11.4 mL, P=0.04), duration of the surgery (78.26±55.2 min vs. 105.16±61.75 min, P=0.027) and administered dose of remifentanil (26.67±6.6 μg vs. 216.2±14.8 μg, P=0.01) were also significantly lower than the control group.

Conclusion

Pre-operative administration of 0.2 mg oral Clonidine in patients undergoing total thyroidectomy results in improved perioperative hemodynamic stability and reduced response to perioperative stress.

Evaluation and Management of the Physiologically Difficult Airway: Consensus Recommendations From Society for Airway Management

Multiple international airway societies have created guidelines for the management of the difficult airway. In critically ill patients, there are physiologic derangements beyond inadequate airway protection or hypoxemia. These risk factors contribute to the "physiologically difficult airway" and are associated with complications including cardiac arrest and death. Importantly, they are largely absent from international guidelines. Thus, we created management recommendations for the physiologically difficult airway to provide practical guidance for intubation in the critically ill. Through multiple rounds of in-person and telephone conferences, a multidisciplinary working group of 12 airway specialists (Society for Airway Management's Special Projects Committee) over a time period of 3 years (2016-2019) reviewed airway physiology topics in a modified Delphi fashion. Consensus agreement with the following recommendations among working group members was generally high with 80% of statements showing agreement within a 10% range on a sliding scale from 0% to 100%. We limited the scope of this analysis to reflect the resources and systems of care available to out-of-operating room adult airway providers. These recommendations reflect the practical application of physiologic principles to airway management available during the analysis time period.

Emergency Neuropharmacology

Management of acute neurologic disorders in the emergency department is multimodal and may require the use of medications to decrease morbidity and mortality secondary to neurologic injury. Clinicians should form an individualized treatment approach with regard to various patient specific factors. This review article focuses on the pharmacotherapy for common neurologic emergencies that present to the emergency department, including traumatic brain injury, central nervous system infections, status epilepticus, hypertensive emergencies, spinal cord injury, and neurogenic shock.

Comparison of hemodynamic responses to laryngoscopy and intubation using Macintosh or McCoy or C-MAC laryngoscope during uniform depth of anesthesia monitored by entropy

Background and Aims:

Laryngoscopy forms an important part of general anesthesia and endotracheal intubation. The aim of the present study was to compare the hemodynamic responses to Laryngoscopy and Intubation using Macintosh or McCoy or C-MAC Laryngoscope with M-Entropy module monitoring to ensure uniform and adequate depth of anesthesia, during and after intubation.

Material and Methods:

A prospective, randomised, comparative study was done and patients included were of 18 to 60 years, ASA (American Society of Anesthesiologist) physical status I and II of both sexes undergoing elective surgery under general anesthesia. They were assigned to three groups using simple randomisation, after securing IV (intravenous) access, standard monitoring and Entropy leads were attached. General anesthesia was administered with glycopyrrolate 0.1 mg, fentanyl 2 ug/kg and intravenous thiopentone, 4 mg/kg. Adequate muscle relaxation was achieved with atracurium 0.6 mg/kg IV. By titrating isoflurane concentration, Entropy maintained between 40 and 60, orotracheal intubation done, with Macintosh or McCoy or C-MAC blades according to simple randomisation. Size of laryngoscope blade, time taken for laryngoscopy and intubation were noted. Heart rate, blood pressure, RE (Response Entropy) and SE (State Entropy) were noted before and during induction and laryngoscopy and post intubation up to 5 minutes. Statistical analysis done using NCSS 9 version 9.0.8 statistical software.

Results:

Hemodynamic responses during laryngoscopy and intubation using Macintosh or McCoy or C-MAC laryngoscope were statistically insignificant (p > 0.05) between the three groups, provided the depth of anesthesia is maintained constant.

Conclusions:

It is the depth of anesthesia that decides the magnitude of hemodynamic responses and not the choice of laryngoscope.

Comparison of fentanil and remifentanil for coronary artery surgery with low ejection fraction

Introduction

In this study, we evaluated patient response and haemodynamic parameters in patients with low ejection fraction undergoing coronary bypass surgery with either fentanil or remifentanil in conjunction with etomidate.

Material and methods

We evaluated 30 cases of coronary artery surgery, which were divided into two treatment groups (n = 15 each). In group F (fentanil group), the following regimen was employed for anaesthesia induction: 1 mg/kg lidocaine, 0.3 mg/kg etomidate, and, following a 1 µg/kg 60 s bolus dose of fentanil, a 0.1 µg/kg/min fentanil infusion was initiated, after which 0.6 mg/kg rocuronium was administered. In group R (remifentanil group), the following regimen was employed for anaesthesia induction: 1 mg/kg lidocaine, 0.3 mg/kg etomidate and, following a 1 µg/kg 60 s bolus dose of remifentanil, a 0.1 µg/kg/min remifentanil infusion was initiated, after which 0.6 mg/kg rocuronium was administered. Systolic artery pressure, diastolic artery pressure, mean arterial pressure, heart rate, SPO₂ (saturation), cardiac output, stroke volume variance, central venous pressure, and systemic vascular resistance values were recorded for all study patients at five minutes before anaesthetic induction (T1), immediately following induction (T2), and immediately following intubation (T3).

Results

The demographic values obtained for both groups were similar. We found that remifentanil use was associated with decreased cardiac output and increased fluctuations in both heart rate and mean values of arterial pressure.

Conclusions

Although many studies have demonstrated remifentanil to be as safe as fentanil when titrated to an appropriate dose, our study suggests that fentanil may be a more appropriate choice during the induction of anaesthesia in patients with a low ejection fraction.

Rapid Sequence Intubation in Traumatic Brain-injured Adults

Deciding on proper medication administration for the traumatic brain injury (TBI) patient undergoing intubation can be daunting and confusing. Pretreatment with lidocaine and/or vecuronium is no longer recommended; however, high-dose fentanyl can be utilized to help blunt the sympathetic stimulation of intubation. Induction with etomidate is recommended; however, ketamine can be considered in the proper patient population, such as those with hypotension. Paralysis can be performed with either succinylcholine or rocuronium, with the caveat that rocuronium can lead to delays in proper neurological examinations due to prolonged paralysis. Recommendations for post-intubation continuous sedation medications include a combination propofol and fentanyl in the normotensive/hypertensive patient population. A combination midazolam and fentanyl or ketamine alone can be considered in the hypotensive patient.

Clinical Practice and Risk Factors for Immediate Complications of Endotracheal Intubation by Intensive Care Unit Doctors in a Regional Hospital in Hong Kong

Background

Endotracheal intubation in critically ill patients is often challenging and is associated with a high complication rate. Intensive Care Unit (ICU) doctors are often responsible for emergency intubation but local data about their experience is lacking.

Objective

To describe the ICU team's practice of endotracheal intubation in critically ill patients in a regional hospital; to evaluate the incidence of immediate complications; and to identify risk factors for complications and predictors for successful intubation.

Design

Retrospective, observational study

Patients

All patients who received endotracheal intubation by the ICU team of the study centre between the 1st July 2013 and 31st December 2013.

Results

Complete data from 325 endotracheal intubations were analyzed. The commonest diagnosis was pneumonia (41.5%) and the mostly frequently cited indication for endotracheal intubation was respiratory failure (50.8%). Complications occurred in 25.5% of all intubations including 4 cases of cardiac arrest after the procedure. Haemodynamic alterations (hypotension and hypertension occurred in 9.2% and 7.4% respectively) were the most common complications. Overall, 96.6% of intubations were successful on the first two attempts. Logistic regression analyses showed that reduced mouth opening was a significant risk factor for immediate complications (odds ratio [OR] 15.98, 95% confidence interval [CI]: 2.71 to 94.41, P=0.006). Cormack-Lehane laryngoscope grading below 2b (OR 0.2, 95% CI: 0.07-0.59, P=0.003) and operator with more than 6 months of formal anaesthetic training (OR 7.06, 95% CI: 1.63 to 30.62, P=0.009) were independent predictors for successful intubation.

Conclusion

The ICU team achieves a high successful rate of emergency endotracheal intubation. High rates of anticipated and unanticipated difficult airway are encountered. Reduced mouth opening is a significant risk factor for complications occurrence. Cormack-Lehane laryngoscopic grading below 2b and intubation performer with more than 6 months of formal anaesthetic training are significant independent predictors for successful intubation. (Hong Kong j.emerg.med. 2016;23:135-144)

A Comparative Study of Dexmedetomidine and Diltiazem for Attenuating Pressor Responses to Laryngoscopy and Endotracheal Intubation: A Double-blind, Randomized Study

CONTEXT

Endotracheal intubation has been suggested to be one of the most invasive stimuli in anesthesia, particularly during induction and after tracheal intubation. The present study aims to evaluate the efficacy of dexmedetomidine as compared to diltiazem on hemodynamic response to laryngoscopy and intubation.

AIMS

To assess and compare the hemodynamic response of dexmedetomidine as compared to diltiazem in patients undergoing laryngoscopy and intubation and rate and type of side effects of the drugs if any.

SETTINGS AND DESIGN

This study design was a prospective, randomized, and double-blind trial.

SUBJECTS AND METHODS

The patients were randomly allocated into three groups: Group I (control), Group II (dexmedetomidine), and Group III (diltiazem) of 45 patients each. Group I (n = 45): 0.9% NaCl 10 ml was given to the patients over 10 min before intubation in Group I (control). Group II (n = 45): injection dexmedetomidine (0.5 μg/kg) in 10 ml normal saline was given to the patients over 10 min before intubation. Group III (n = 45): injection diltiazem (0.3 mg/kg) in 10 ml normal saline was given to the patients over 10 min before intubation.

STATISTICAL ANALYSIS USED

The data so collected were subjected to statistical analysis using Statistical Package for the Social Sciences version 15.0.

RESULTS

Mean percentage increase in systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) following intubation was 17.90%, 19.96%, and 19.04%, respectively, in control group, 9.04%, 6.32%, and 7.53%, respectively, in dexmedetomidine group, and 12.30%, 10.32%, and 11.14%, respectively, in diltiazem groups. Statistically, there was a significant difference in postintubation SBP, DBP, and MAP of the three groups (P < 0.001). Dexmedetomidine at a dose of 0.5 μg/kg showed to have a better attenuation of pressor response as compared to diltiazem at a dose of 0.3 μg/kg.

CONCLUSIONS

Both dexmedetomidine and diltiazem were safe and effective in attenuating the hemodynamic response following laryngoscopy and endotracheal intubation; however, between two trial drugs, dexmedetomidine had a better response.

Comparison of the efficacy of lornoxicam and fentanyl in attenuating the hemodynamic response to laryngoscopy and intubation

BACKGROUND AND OBJECTIVES

Laryngoscopy and intubation elicits huge spectrum of stress response which is hazardous in high-risk patients. Many drugs and techniques have been used to attenuate the stress response. Lornoxicam 16 mg is a potent nonsteroidal anti-inflammatory drug agent with analgesic potency equivalent to morphine 10 mg, fentanyl 100 μg and tramadol 100 mg. Lornoxicam has been found to attenuate stress response in some studies. We compared the lornoxicam with fentanyl in attenuating stress response.

MATERIALS AND METHODS

A double blind randomized controlled study was conducted on 60 adult patients of American Society of Anesthesiologist physical status 1 and 2. Group L (n = 30) receives injection lornoxicam 16 mg intravenous 30 min before induction, Group F (n = 30) receives injection fentanyl 2 μg/kg during induction. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) were recorded baseline (BL), before induction, every minute up to 5 min and at 10 min after intubation.

RESULTS

After intubation, there is a gradual decrease in SBP and DBP in both groups. The MAP was also comparable between the two groups except at 5 min and 10 min during which MAP recovered toward BL in Group L where as it remained low in Group F which was statistically significant (P < 0.05). Both the drugs have successfully attenuated the HR response.

CONCLUSION

Lornoxicam successfully attenuated the hemodynamic response to laryngoscopy and endotracheal intubation and is equally efficacious as fentanyl.

Use of lidocaine and fentanyl premedication for neuroprotective rapid sequence intubation in the emergency department

Introduction:

Autoregulation is dysfunctional in the injured brain. Increases in intracranial and arterial pressure may therefore result in extension of the primary injury. Rapid sequence intubation (RSI) is a well-known cause of surges in both arterial pressure and intracranial pressure. Neuroprotective agents, namely lidocaine and fentanyl, have the potential to minimize the pressure surges implicated in secondary brain injury. The purpose of this study was to determine the frequency with which neuroprotective agents were used for neuroprotective RSI in the emergency department.

Methods:

We conducted a retrospective chart review of all 139 patients intubated in the emergency department of Vancouver General Hospital between March and October 2003. Patients were eligible if there was an indication for neuroprotective agents defined as presumed intracranial pathology and a mean arterial pressure (MAP) &gt; 85 mm Hg. Contraindications to fentanyl included MAP &lt; 85 mm Hg or allergy to fentanyl.

Results:

Seventy-seven patients were intubated for primary neurological indications. Indication for intubation included non-traumatic causes (n = 37) (including cerebrovascular accident or intracranial hemorrhage) and closed head injury (n = 40). The mean age (± standard deviation) was 52.3 ± 20.4 years, and 31.4% were female. Fifty-seven (74.0%) patients had indications for neuroprotective agents, without contraindications. When neuroprotective agents were indicated, lidocaine was used in 84.2% (95% confidence interval [CI] 72.6%–91.5%) of patients while fentanyl was used in 33.3% (95%CI 22.4%–46.3%) of patients. Eleven percent of the intubations were performed with a fentanyl dose of Δ 2 mcg/kg, which is the lower limit considered effective.

Conclusions:

Despite the potential benefit of using lidocaine and fentanyl in appropriate patients undergoing neuroprotective RSI in the emergency department, our study identified a significant underutilization of optimal premedication. The identification of barriers to use and the implementation of strategies to optimize use are necessary.

Premedication with clonidine versus fentanyl for intraoperative hemodynamic stability and recovery outcome during laparoscopic cholecystectomy under general anesthesia

BACKGROUND

Laparoscopic cholecystectomy under general anesthesia induced intraoperative hemodynamic responses which should be attenuated by appropriate premedication. The present study was aimed to compare the clinical efficacy of clonidine and fentanyl premedication during laparoscopic cholecystectomy for attenuation of hemodynamic responses with postoperative recovery outcome.

SUBJECTS AND METHODS

In this prospective randomized double blind study 64 adult consented patients of either sex with ASA I and II, scheduled for elective laparoscopic cholecystectomy under general anesthesia and met the inclusion criteria, were allocated into two groups of 32 patients. Group C patients have received intravenous clonidine 1μg kg(-1) and Group F patients have received intravenous fentanyl 2μg kg(-1) 5 min before induction. Anesthetic and surgical techniques were standardized. All patients were assessed for intraoperative hemodynamic changes at specific time and postoperative recovery outcome.

RESULTS

Premedication with clonidine or fentanyl has attenuated the hemodynamic responses of laryngoscopy and laparoscopy. Clonidine was superior to fentanyl for intraoperative hemodynamic stability. No significant differences in the postoperative recovery outcome were observed between the groups. Nausea, vomiting, shivering and respiratory depression were comparable between groups.

CONCLUSION

Premedication with clonidine or fentanyl has effectively attenuated the intraoperative hemodynamic responses of laparoscopic cholecystectomy.

Pregabalin premedication - A new treatment option for hemodynamic stability during general anesthesia: A prospective study

Background:

Hemodynamic responses of laryngoscopy, intubation, and pain are powerful noxious stimulus which should be attenuated by the appropriate premedication, smooth induction, and rapid intubation.

Context:

The oral pregabalin may attenuate the hemodynamic pressor response with intraoperative hemodynamic stability.

Aims:

The present study was designed to evaluate the clinical efficacy and safety of oral pregabalin for hemodynamic stability.

Settings and Design:

This is a prospective blind randomized controlled cohort observation study.

Materials and Methods:

The 80 adult consented patients of ASA grade I and II of either gender aged 24–54 years who met the inclusion criteria were randomized to receive oral pregabalin 150 mg or placebo capsule, given 60–75 min before surgery. Patients were premedicated with metoclopramide (10 mg), glycopyrrolate (0.2 mg), and fentanyl (1 μg/kg). Anesthesia was induced with propofol and rocuronium and maintained with isoflurane, nitrous oxide, and oxygen. Both groups were assessed for preoperative sedation and changes in heart rate and mean arterial blood pressure before and after the induction and 1, 3, 5, and 10 min after laryngoscopy and intubation, then at 5 min intervals till end of surgery along with postoperative complications.

Statistical Analysis:

The hemodynamic variables were analyzed by using analysis of variance (ANOVA), Student's t test, and chi square test as appropriate.

Results:

Preoperative sedation was higher with pregabalin with no significant change in heart rate. The mean arterial pressure was attenuated with oral pregabalin to statistically significant value (P<0.007). The requirement of analgesic drug was reduced with no postoperative respiratory depression, nausea, or vomiting and hemodynamic parameters remained stabilized perioperatively.

Conclusions:

Oral pregabalin premedication effectively leads to sedation and analgesia with successful attenuation of the adverse and deleterious hemodynamic pressor response.

[The effect of different doses of esmolol on hemodynamic, bispectral index and movement response during orotracheal intubation: prospective, randomized, double-blind study]

OBJECTIVE

A prospective, randomized and double-blind study was planned to identify the optimum dose of esmolol infusion to suppress the increase in bispectral index values and the movement and hemodynamic responses to tracheal intubation.

MATERIALS AND METHODS

120 patients were randomly allocated to one of three groups in a double-blind fashion. 2.5mgkg(-1) propofol was administered for anesthesia induction. After loss of consciousness, and before administration of 0.6mgkg(-1) rocuronium, a tourniquet was applied to one arm and inflated to 50mmHg greater than systolic pressure. The patients were divided into 3 groups; 1mgkg(-1)h(-1) esmolol was given as the loading dose and in Group Es50 50μgkg(-1)min(-1), in Group Es150 150μgkg(-1)min(-1), and in Group Es250 250μgkg(-1)min(-1) esmolol infusion was started. Five minutes after the esmolol has been begun, the trachea was intubated; gross movement within the first minute after orotracheal intubation was recorded.

RESULTS

Incidence of movement response and the ΔBIS max values were comparable in Group Es250 and Group Es150, but these values were significantly higher in Group Es50 than in the other two groups. In all three groups in the 1st minute after tracheal intubation heart rate and mean arterial pressure were significantly higher compared to values from before intubation (p<0.05). In the study period there was no significant difference between the groups in terms of heart rate and mean arterial pressure.

CONCLUSION

In clinical practise we believe that after 1mgkg(-1) loading dose, 150μgkg(-1)min(-1) iv esmolol dose is sufficient to suppress responses to tracheal intubation without increasing side effects.

Preliminary observations on the vasomotor responses to electrical stimulation of the ventrolateral surface of the human medulla

Object

Pulsatile arterial compression (AC) of the ventrolateral medulla (VLM) is hypothesized to produce the hypertension in a subset of patients with essential hypertension. In animals, a network of subpial neuronal aggregates in the VLM has been shown to control cardiovascular functions. Although histochemically similar, neurons have been identified in the retro-olivary sulcus (ROS) of the human VLM, but their function is unclear.

Methods

The authors recorded cardiovascular responses to electrical stimulation at various locations along the VLM surface, including the ROS, in patients who were undergoing posterior fossa surgery for trigeminal neuralgia. This vasomotor mapping of the medullary surface was performed using a bipolar electrode, with stimulation parameters ranging from 5- to 30-second trains (20–100 Hz), constant current (1.5–5 mA), and 0.1-msec pulse durations. Heart rate (HR) and blood pressure (BP) were recorded continuously from baseline (10 seconds before the stimulus) up to 1 minute poststimulus. In 6 patients, 17 stimulation responses in BP and HR were recorded.

Results

The frequency threshold for any cardiovascular response was 20 Hz; the stimulation intensity threshold ranged from 1.5 to 3 mA. In the first patient, all stimulation responses were significantly different from sham recordings (which consisted of electrodes placed without stimulations). Repeated stimulations in the lower ROS produced similar responses in 3 other patients. Two additional patients had similar responses to single stimulations in the lower ROS. Olive stimulation produced no response (control). Hypotensive and/or bradycardic responses were consistently followed by a reflex hypertensive response. Slight right/left differences were noted. No patient suffered short- or long-term effects from this stimulation.

Conclusions

This stimulation technique for vasomotor mapping of the human VLM was safe and reproducible. Neuronal aggregates near the surface of the human ROS may be important in cardiovascular regulation. This method of vasomotor mapping with measures of responses in sympathetic tone (microneurography) should yield additional data for understanding the neuronal network that controls cardiovascular functions in the human VLM. Further studies in which a concentric bipolar electrode is used to generate this type of vasomotor map should also increase understanding of the pathophysiological mechanisms of neurogenically mediated hypertension, and assist in the design of studies to prove the hypothesis that it is caused by pulsatile AC of the VLM.

A comparative study of efficacy of esmolol and fentanyl for pressure attenuation during laryngoscopy and endotracheal intubation

OBJECTIVE

To compare the effectiveness of single bolus dose of esmolol or fentanyl in attenuating the hemodynamic responses during laryngoscopy and endotracheal intubation.

METHODS

Ninety adult ASA I and ASA II patients were included in the study who underwent elective surgical procedures. Patients were divided into three groups. Group C (control) receiving 10 ml normal saline, group E (esmolol) receiving bolus dose of esmolol 2 mg/kg and group F (fentanyl) receiving bolus dose of fentanyl 2 µg/kg intravenously slowly. Study drug was injected 3 min before induction of anesthesia. Heart rate, systemic arterial pressure and ECG were recorded as baseline and after administration of study drug at intubation and 15 min thereafter.

RESULTS

Reading of heart rate, blood pressure and rate pressure product were compared with baseline and among each group. The rise in heart rate was minimal in esmolol group and was highly significant. Also the rate pressure product at the time of intubation was minimal and was statistically significant rate 15 min thereafter in group E.

CONCLUSION

Esmolol 2 mg/kg as a bolus done proved to be effective in attenuating rises in heart rate following laryngoscopy and intubation while the rise in blood pressure was suppressed but not abolished by bolus dose of esmolol.

Scandinavian clinical practice guidelines on general anaesthesia for emergency situations

Emergency patients need special considerations and the number and severity of complications from general anaesthesia can be higher than during scheduled procedures. Guidelines are therefore needed. The Clinical Practice Committee of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine appointed a working group to develop guidelines based on literature searches to assess evidence, and a consensus meeting was held. Consensus opinion was used in the many topics where high-grade evidence was unavailable. The recommendations include the following: anaesthesia for emergency patients should be given by, or under very close supervision by, experienced anaesthesiologists. Problems with the airway and the circulation must be anticipated. The risk of aspiration must be judged for each patient. Pre-operative gastric emptying is rarely indicated. For pre-oxygenation, either tidal volume breathing for 3 min or eight deep breaths over 60 s and oxygen flow 10 l/min should be used. Pre-oxygenation in the obese patients should be performed in the head-up position. The use of cricoid pressure is not considered mandatory, but can be used on individual judgement. The hypnotic drug has a minor influence on intubation conditions, and should be chosen on other grounds. Ketamine should be considered in haemodynamically compromised patients. Opioids may be used to reduce the stress response following intubation. For optimal intubation conditions, succinylcholine 1-1.5 mg/kg is preferred. Outside the operation room, rapid sequence intubation is also considered the safest method. For all patients, precautions to avoid aspiration and other complications must also be considered at the end of anaesthesia.

Intravenous Nicardipine

Nicardipine is a water soluble calcium channel antagonist, with predominantly vasodilatory actions. Intravenous (IV) nicardipine (Cardene IV), which demonstrates a relatively rapid onset/offset of action, is used in situations requiring the rapid control of blood pressure (BP). IV nicardipine was as effective as IV nitroprusside in the short-term reduction of BP in patients with severe or postoperative hypertension. A potential role for IV nicardipine in the intraoperative acute control of BP in patients undergoing various surgical procedures (including cardiovascular, neurovascular and abdominal surgery), and in the deliberate induction of reduced BP in surgical procedures in which haemostasis may be difficult (e.g. surgery involving the hip or spine) was demonstrated in preliminary studies. Preliminary studies also indicated the ability of a bolus dose of IV nicardipine to attenuate the hypertensive response, but not the increase in tachycardia, after laryngoscopy and tracheal intubation in anaesthetised patients. In large, well designed studies, IV nicardipine prevented cerebral vasospasm in patients with recent aneurysmal subarachnoid haemorrhage; however, overall clinical outcomes at 3 months were similar to those in patients who received standard management. Small preliminary studies have investigated the use of IV nicardipine in a variety of other settings, including acute intracerebral haemorrhage, acute ischaemic stroke, pre-eclampsia, acute aortic dissection, premature labour and electroconvulsive therapy.In conclusion, the efficacy of IV nicardipine in the short-term treatment of hypertension in settings for which oral therapy is not feasible or not desirable is well established. The ability to titrate IV nicardipine to the tolerance levels of individual patients makes this agent an attractive option, especially in critically ill patients or those undergoing surgery. Potential exists for further investigation of the use of this agent in clinical settings where a vasodilatory agent with minimal inotropic effects is appropriate.

Combined use of esmolol and nicardipine to blunt the haemodynamic changes following laryngoscopy and tracheal intubation

We examined the effect of different combinations of esmolol and nicardipine upon the circulatory response to tracheal intubation. One hundred patients were randomly allocated into five groups of twenty to receive pretreatments of saline or different combinations of esmolol (0.5 or 1.0 mg x kg(-1)) and nicardipine (15 or 30 microg x kg(-1)). Significant tachycardia persisted over a 5-min period after intubation in all five groups compared with baseline levels (p < 0.05). Patients receiving esmolol 1.0 mg x kg(-1) and nicardipine 30 g x kg(-1) showed no significant change in systolic blood pressure after tracheal intubation compared with baseline and significant lower peak systolic blood pressure than those receiving saline (p = 0.023).

Rapid sequence induction: a national survey of practice

We performed a national postal survey exploring anaesthetists' practice in rapid sequence induction. All respondents used pre-oxygenation, although the technique employed, and its reliability, varied. Thiopental and succinylcholine, given after waiting for signs of loss of consciousness, were the most widely used drugs for rapid sequence induction. Propofol and rocuronium were used by more than a third of respondents, and most respondents (75%) also routinely administered an opioid. Cricoid pressure was used universally but the practice of its application varied widely. The commonest aids used if intubation was difficult were the gum elastic bougie, the long laryngoscope blade and the laryngeal mask. After failed intubation, approximately half of respondents would maintain the supine position. Failure to intubate at rapid sequence intubation had been seen by 45% of respondents but harm was uncommon. In contrast, 28% had seen regurgitation, which frequently led to considerable harm and to three deaths. In spite of this, practice of a failed intubation drill was uncommon (15%) and anaesthetic assistants were rarely known to practice application of cricoid pressure. Consultants were less likely than trainees to use rocuronium as a muscle relaxant, and more likely to choose morphine if administering an opioid. They were less likely to practice a failed intubation drill. Other aspects of practice varied little between grades. This survey suggests that many anaesthetists do not follow best practice when performing a rapid sequence induction.

Assessment of the efficacy of esmolol on the haemodynamic changes induced by laryngoscopy and tracheal intubation: a meta-analysis

BACKGROUND

Adrenergic stress response induced by laryngoscopy and tracheal intubation (LTI) appears to be attenuated by esmolol, but its potential clinical benefits have not been fully weighed against possible adverse effects.

METHODS

A systematic search up to May 2000 was performed using MEDLINE, EMBASE, LILACS, Cochrane library, manual searching and bibliographies in all languages. All randomised comparisons of esmolol with placebo on the haemodynamic changes elicited by LTI were obtained. Trials were included in the present meta-analysis if they recorded heart rate (HR), systolic pressure (SBP), mean arterial pressure (MAP) or diastolic pressure (DBP) at three different stages: pre-induction, immediately prior to intubation, and in the post-intubation period. Weighted mean differences (WMD) and 95% confidence intervals (CI) of the changes in the haemodynamic variables between treatment and placebo groups were calculated.

RESULTS

Of 72 publications identified, 38 randomised controlled trials containing a total of 2009 patients were finally included. Eleven different regimens and doses of esmolol demonstrated effectiveness in the attenuation of HR and BP after LTI in a dose-dependent manner. The most effective regimen was a loading dose of 500 microg x kg(-1) x min(-1) over 4 min followed by continuous infusion dose of 200-300 microg x kg(-1) x min(-1) [WMD: 20.2 bpm (95% CI: 15.6 to 24.7)]. High bolus dose (200 mg) of esmolol produced a considerable decrease in DBP [WMD 10.1 mmHg (95% CI: 7.3 to 12.8)].

CONCLUSION

Esmolol is effective, in a dose-dependent manner, in the attenuation of the adrenergic response to LTI. To minimise its adverse effects it should be administered, when considered clinically appropriate, as a continuous infusion regimen.

Antinociceptive and cardiovascular properties of esmolol following formalin injection in rats

PURPOSE

To assess the role of esmolol, a beta1 receptor blocker, in the modulation of pain in the absence of anesthesia.

METHODS

Rats were chronically instrumented to record mean arterial blood pressure (MAP) and heart rate (HR). Animals were divided into three groups. Group 1 [esmolol high (EH) 150 mg x kg(-1) x hr(-1); n = 9], Group 2 [esmolol low (EL) 40 mg x kg(-1) x hr(-1); n = 7] and Group 3 saline (n = 9). Formalin 5% was injected in the rat hind paw. Formalin-induced lifting, MAP and HR were recorded at five minute intervals for 35 min after formalin injection.

RESULTS

Formalin was associated with an early (Phase 1; 0-5 min) and late nociceptive response (Phase 2; 10-35 min). Esmolol did not affect Phase 1. Although low dose esmolol had minimum effects on nociceptive Phase 2, it was diminished with high dose esmolol. Formalin induced biphasic increases in MAP and HR. Although esmolol did not affect the initial increase in MAP, high dose esmolol blunted the secondary increase in MAP Both low and high doses of esmolol inhibited formalin-induced tachycardia during the first 30 min.

CONCLUSION

Our data suggest that esmolol leads to analgesia and reduction of cardiovascular responses to pain.

Advances in airway pharmacology. Emerging trends and evolving controversy

The practice of emergency medicine is a constant onslaught of decision making and challenges and the issues of airway management are no exception. Obtaining proper airway control requires thoughtful organization and planning, and necessitates a thorough working knowledge of the drugs or medications employed. Because there are so many agents available, expertise in airway pharmacology has become essential. The emergency physician who is well versed in the uses, and the physiologic effects, contraindications, and alternatives of drugs administered is both providing immediate intervention and positively affecting patient outcome, which is certainly a goal worth achieving.

The use of esmolol, nicardipine, or their combination to blunt hemodynamic changes after laryngoscopy and tracheal intubation

Laryngoscopy and tracheal intubation (LTI) often provoke an undesirable increase in blood pressure (BP) and/or heart rate (HR). We tested the premise that nicardipine (NIC) and esmolol (ESM) in combination (COMB) would oppose both. Adult surgical patients received pretreatment (randomized) with IV bolus NIC 30 microg/kg (n = 31), ESM 1.0 mg/kg (n = 34), or COMB (one-half dose each, n = 32). Peak BP and HR after LTI were compared with controls (CONT; n = 35) with no pretreatment. Anesthetic induction was standardized: IV thiopental (5-7 mg/kg), fentanyl (1-2 microg/kg), and succinylcholine (1.5 mg/kg). Systolic (S), diastolic (D), and mean (M) BP and HR awake before pretreatment (baseline) were similar in all test groups. No patient was treated for hypotension, bradycardia, or tachycardia after pretreatment or anesthetic induction. Peak HR after LTI was increased versus baseline in CONT and all test groups, but did not differ from CONT among the test groups. Peak SBP and DBP increased versus baseline in CONT, and with ESM and NIC, but not COMB. Peak SBP, DBP, and MBP were increased with ESM versus COMB, and peak DBP with ESM versus NIC. Compared with no pretreatment before the IV induction of general anesthesia, the peak increase in BP after LTI is best blunted by the combination of nicardipine and ESM, compared with either drug alone. No single drug or combination in the doses tested opposed increased HR.

IMPLICATIONS

Compared with no pretreatment before the IV induction of general anesthesia, the peak increase in blood pressure after laryngoscopy and tracheal intubation is best blunted by the combination of nicardipine and esmolol, compared with either drug alone. No single drug or combination in the doses tested opposed increased heart rate.

Effects of anesthetic technique on the hemodynamic response to microlaryngeal surgery

Our aim was to study the attenuation of the hemodynamic response to microlaryngeal surgery by beta-blocking agents used as support drugs to the anesthetic technique. The study was carried out in 30 patients randomly allocated to one of three groups. The control group received only anesthetic drugs. The second group received labetalol hydrochloride 0.3 mg/kg 3 minutes before induction and 0.15 mg/ kg 2 minutes prior to the start of suspension of the larynx. The third group received esmolol hydrochloride 500 micrograms/kg 3 minutes prior to induction and a continuous infusion of 300 micrograms/kg during the surgical procedure. Hemodynamic data in the three groups were compared by analysis of variance. A statistically significant difference (p < .05) was found in hemodynamic data among the two groups treated with blocking agents and the control group. The addition of beta-blocking agents to the anesthetic technique attenuates the hemodynamic response to suspension laryngoscopy.

Effect of esmolol on the heart rate, arterial pressure and electrocardiographic changes during laryngomicroscopy

BACKGROUND

Laryngomicroscopy causes considerable haemodynamic and ECG changes and therefore requires high doses of anaesthetic agents, which prolong recovery. In this double-blind randomized work, we studied the effect of esmolol, a short-acting beta-adrenergic receptor-blocking agent, on haemodynamic and ECG changes during laryngomicroscopy under thiopental-alfentanil-isoflurane-suxamethonium anaesthesia.

METHODS

Forty ASA class I-II patients (mean age 43 +/- 11 yr) were allocated to receive either esmolol 1 mg.kg-1 + 200 micrograms.kg-1.min-1 (the esmolol group) or saline (the control group). Heart rate and arterial pressure were measured noninvasively and ECG was analyzed with the aid of a microcomputer. Comparisons between the groups were performed using two-way analysis of variance with repeated measures and the Student's t-test.

RESULTS

In the presence of esmolol, neither the heart rate nor the QTc interval of the ECG increased significantly when compared with the baseline values, with the exception that the QTc interval was increased after intubation. The increase in arterial pressure after insertion of the operating laryngoscope was not prevented in esmolol-treated patients. No cardiac arrhythmias occurred in either of the groups.

CONCLUSIONS

On the basis of the present study, esmolol-bolus + infusion during alfentanil-isoflurane anaesthesia in healthy, middle-aged patients is a useful treatment in circumstances where an increase of the heart rate, prolongation of the QTc interval and cardiac arrhythmias should be avoided.

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 efficacy of guanfacine in reducing perioperative hemodynamic changes and volatile anesthetic requirement

STUDY OBJECTIVE

To evaluate the efficacy of guanfacine, an alpha 2-adrenergic agonist, for attenuating hemodynamic changes associated with tracheal intubation or extubation, providing intraoperative hemodynamic stability, and reducing inhalation anesthetic requirement in patients undergoing gynecologic surgery.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

Inpatient gynecology at a university hospital.

PATIENTS

45 women (ASA I) undergoing elective abdominal hysterectomy.

INTERVENTIONS

Guanfacine and placebo supplementation. Oral guanfacine at 0.5 or 1 mg or a placebo (control) 3 hours before induction of anesthesia. Anesthesia was induced with thiamylal 5 mg/kg and vecuronium 0.2 mg/kg, and maintained with isoflurane and 50% nitrous oxide (N2O) in oxygen. The inspired isoflurane concentration was maintained at 1% during the first 5 minutes following induction of anesthesia and titrated to the concentration required to maintain hemodynamic stability [defined as +/- 10% of systolic blood pressure (SBP)]. The end-tidal concentration of isoflurane was monitored throughout anesthesia. On completion of surgery, N2O and isoflurane were discontinued. Following confirmation of recovery from anesthesia and muscle relaxation, the endotracheal tube was removed.

MEASUREMENTS AND MAIN RESULTS

Patients in the control group showed significant increases in SBP and diastolic blood pressure (DBP) and heart rate (HR) associated with tracheal intubation 50 +/- 5, 57 +/- 6.3, and 45 +/- 4.6 (%, mean +/- SEM, p < 0.05 for any variables), respectively. Plasma norepinephrine and epinephrine concentrations increased to 382 +/- 40 pg/ml and 49 +/- 4.2 pg/ml, respectively (p < 0.05 compared with basal values). These changes were attenuated in patients receiving 1 mg of guanfacine (29 +/- 4.2, 33 +/- 4.5, 25 +/- 3.2, 210 +/- 32, and 22 +/- 3.5, respectively (p < 0.05 for any variables compared with placebo group). Higher inspired concentrations of isoflurane (%) were required in the control and 0.5 mg guanfacine-treated groups (1.2 +/- 0.05 and 1.0 +/- 0.04, respectively) than in the 1 mg guanfacine-treated group (0.62 +/- 0.03) for hemodynamic stability (p < 0.05). Coefficient of variation in HR changes during surgery was 17.2, 13.9, and 8.8 in the placebo, guanfacine 0.5 mg, and guanfacine 1 mg treated groups, respectively. Compared with placebo, guanfacine 1 mg reduced the maximum changes (mean +/- SEM) in SBP (7 +/- 1.2 vs. 18 +/- 2.2) and in HR (23 +/- 2.1 vs. 44 +/- 3.6) occurring during tracheal extubation. The incidence of perioperative complications was similar among the three groups.

CONCLUSION

Guanfacine 1 mg administered orally proved to be an effective premedicant for providing intraoperative hemodynamic stability, attenuating the increase in BP and HR associated with tracheal intubation and extubation, and reducing anesthetic requirements without increasing the incidence of perioperative complications.

Modification of the haemodynamic responses to induction of anaesthesia and tracheal intubation with alfentanil, esmolol and their combination

The purpose of this double-blind randomized work was to study the effect of alfentanil and esmolol and their half-dose combination on the increases of heart rate and arterial pressure and on the prolongation of the QTc interval of the ECG occurring during anaesthetic induction. Sixty ASA class I-II patient with mean age ranging from 26 to 32 yr among the groups. Patients were allocated to one of four equal groups to receive saline, esmolol 2 mg.kg-1, alfentanil 0.03 mg.kg-1 and alfentanil 0.015 mg.kg-1+esmolol 1 mg.kg-1. Anaesthesia was induced with thiopentone. Succinylcholine was used to facilitate tracheal intubation. Haemodynamic variables were measured non-invasively and the QTc interval with the aid of a microcomputer. Comparisons between the groups were performed using two-way analysis of variance with repeated measures. Both alfentanil and alfentanil-esmolol prevented the increase of heart rate and arterial pressure caused by intubation whereas esmolol prevented only the increase of the heart rate. None of the treatments prevented prolongation of the QTc interval after intubation and only alfentanil prevented that after succinylcholine. The present results suggest that in the prevention of the haemodynamic responses to tracheal intubation, the half-dose combination of alfentanil and esmolol is as effective as alfentanil and superior to esmolol. The combination is preferable to relatively large doses of either drug in circumstances where side effects, such as respiratory depression due to alfentanil or bradycardia due to both drugs should be minimized.