Effects of alfentanil on the hemodynamic and catecholamine response to tracheal intubation

Effects of different doses of alfentanil on cardiovascular response to rapid sequence intubation in elderly patients: a parallel-controlled randomized trial

BACKGROUND

Rapid sequence intubation (RSI) have been shown to be effective in preventing reflux aspiration in patients with a full stomach during anaesthesia induction and endotracheal intubation. However, there is currently no standardized operation protocol or anaesthesia induction drug standard for RSI. Furthermore, there is a lack of evidence regarding the use of RSI in patients older than 65. In this study, we aimed to investigate the cardiovascular effects of different doses of alfentanil combined with propofol and etomidate during RSI in elderly patients aged 65-80 years.

METHODS

A total of 96 patients aged 65-80 years who underwent general anaesthesia with tracheal intubation were selected for this study. The patients were randomly assigned to one of four groups using a random number table. Group A patients received an induction dose of 10 µg/kg alfentanil, group B patients received 15 µg/kg alfentanil, group C patients received 20 µg/kg alfentanil, and group D patients received 25 µg/kg alfentanil. Heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), and ejection fraction (EF) were measured at three time points: 5 min before anaesthesia induction (T0), 1 min after endotracheal intubation (T1), and 5 min after endotracheal intubation (T2). Concurrently, 4 ml of arterial blood was collected from patients at three time points, and the concentrations of norepinephrine (NE) and cortisol (Cor) in plasma were detected. Occurrences of hypertension, hypotension, bradycardia and tachycardia during anesthesia induction to 5 min after tracheal intubation were noted.

RESULTS

Compared with T0, the HR, MAP, NE and Cor concentrations in group A and group B were increased at the T1 and T2 time points, CI and EF values were decreased (P < 0.05). HR and MAP in groups C and D were increased at the T1 time point, while they were decreased at the T2 time point in group D (P < 0.05). The changes in CI and EF values, concentrations of NE and Cor, were not significant at T1 and T2 time points in group C (P > 0.05). Additionally, they were not significant in group D at the T1 time point (P > 0.05), but decreased at the T2 time point (P < 0.05). Compared with group A, the HR, MAP, NE and Cor concentrations in groups C and D were decreased at T1 and T2 time points (P < 0.05). The CI and EF values of groups C and D were increased at T1 time point but decreased at T2 time point in group D (P < 0.05). The incidence of hypertension and tachycardia in group A was significantly higher than that in group C and group D (P < 0.05), and the incidence of hypotension and bradycardia in group D was significantly higher than that in group A and group B (P < 0.05).

CONCLUSION

Alfentanil 20 µg/kg for RSI in elderly patients, can effectively inhibit the violent cardiovascular reaction caused by intubation, and avoid the inhibition of cardiovascular system caused by large dose, hemodynamics more stable.

TRIAL REGISTRATION

ChiCTR2200062034 ( www.chictr.org.cn ).

Comparative Study of Gabapentin, Clonidine and Placebo in Alleviating the Hemodynamic Changes Due to Tracheal Intubation and Laryngoscopy

INTRODUCTION

Hemodynamic changes during laryngoscopy and tracheal intubation must be reduced for safe and effective anesthesia. The present study was conducted to compare the efficacy of oral clonidine, gabapentin and placebo in alleviating the hemodynamic changes due to tracheal intubation and laryngoscopy.

METHODS

This was a double-blinded randomized controlled trial conducted on 90 patients who were undergoing elective surgery and were randomized into three groups. Group I (n=30) received a placebo, group II (n=30) received gabapentin and group III (n=30) received clonidine as premedication before anesthesia induction. Patient heart rate and pressor response were recorded periodically and compared between the groups.

RESULTS

There was no significant difference in the baseline heart rate (HR) and mean arterial pressure (MAP) between the groups. HR elevation was observed in all three groups and found to be significant (p=0.0001) but the increase was higher in the placebo (15 min: 80.80± 15.41) and lower in the clonidine group (15 min: 65.53± 12.43). The elevation in systolic and diastolic blood pressure was least and transient in the gabapentin group, as compared to placebo and clonidine group. Intra-operatively, the requirement of opioids was higher in the placebo as compared to clonidine and gabapentin (p < .001).

CONCLUSION

Clonidine and gabapentin were effective in reducing the hemodynamic changes during laryngoscopy and intubation.

Rapid sequence induction (RSI) in trauma patients: Insights from healthcare providers

BACKGROUND

We aimed to describe the current practice of emergency physicians and anaesthesiologists in the selection of drugs for rapid-sequence induction (RSI) among trauma patients.

METHODS

A prospective survey audit was conducted based on a self-administered questionnaire among two intubating specialties. The preferred type and dose of hypnotics, opioids, and muscle relaxants used for RSI in trauma patients were sought in the questionnaire. Data were compared for the use of induction agent, opioid use and muscle relaxant among stable and unstable trauma patients by the intubating specialties.

RESULTS

A total of 102 participants were included; 47 were anaesthetists and 55 were emergency physicians. Propofol (74.5%) and Etomidate (50.0%) were the most frequently used induction agents. Significantly higher proportion of anesthesiologist used Propofol whereas, Etomidate was commonly used by emergency physicians in stable patients (P=0.001). Emergency physicians preferred Etomidate (63.6%) and Ketamine (20.0%) in unstable patients. The two groups were comparable for opioid use for stable patients. In unstable patients, use of opioid differed significantly by intubating specialties. The relation between rocuronium and suxamethonium use did change among the anaesthetists. Emergency physicians used more suxamethonium (55.6% vs. 27.7%, P=0.01) in stable as well as unstable (43.4 % vs. 27.7%, P=0.08) patients.

CONCLUSION

There is variability in the use of drugs for RSI in trauma patients amongst emergency physicians and anaesthesiologists. There is a need to develop an RSI protocol using standardized types and dose of these agents to deliver an effective airway management for trauma patients.

Dose requirements of alfentanil to eliminate autonomic responses during rapid-sequence induction with thiopental 4 mg/kg and rocuronium 0.6 mg/kg

STUDY OBJECTIVE

Opioids are integral part of anesthesia induction, but information on optimal dosing is limited. We aimed to determine doses of alfentanil needed to eliminate increases in 5 autonomic response variables (plasma concentrations of epinephrine, norepinephrine and vasopressin, arterial blood pressure [ABP], and heart rate) during rapid-sequence induction of anesthesia with thiopental 4 mg/kg and rocuronium 0.6 mg/kg.

DESIGN

Prospective, randomized, observer-blinded, interventional clinical study.

SETTING

Large academic institution.

PATIENTS

Eighty-four healthy patients, aged 18 to 55 years, received 1 of 7 assessor-blinded doses of alfentanil (0, 10, 20, 30, 40, 50, and 60 μg/kg) together with thiopental 4 mg/kg and rocuronium 0.6 mg/kg, administered in rapid succession (15 seconds). Laryngoscopy was initiated 40 seconds after rocuronium, and tracheal intubation was concluded within 15 seconds thereafter.

MEASUREMENTS

An indwelling radial artery catheter was used for hemodynamic monitoring and blood sampling. Relationships between alfentanil dose and response variables were tested with linear regression, and the influence of covariates (sex, body weight, and age) was determined. Alfentanil dose needed to prevent increases in ABP >10% above baseline with 95% probability was estimated with logistic regression.

MAIN RESULTS

Significant relationships were determined between alfentanil dose and response variables. Clinically interesting influence of covariates was not found. Alfentanil 55 μg/kg was needed to prevent increases in ABP postintubation >10% above baseline with 95% probability. One individual needed a bolus of vasopressor postintubation.

CONCLUSIONS

Optimal control of autonomic responses during rapid-sequence induction was achieved with clinically relevant doses of alfentanil in healthy patients anesthetized with thiopental 4 mg/kg and rocuronium 0.6 mg/kg.

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.

Alfentanil during rapid sequence induction with thiopental 4 mg/kg and rocuronium 0.6 mg/kg: tracheal intubation conditions

BACKGROUND

Opioids have become an integral part of anaesthesia induction. We aimed to determine the dose of alfentanil needed to obtain perfect tracheal intubation conditions during rapid sequence induction with standard doses of thiopental and rocuronium, where laryngoscopy was initiated 55 s after commencement of drug administration. The influence of covariates (sex, body weight, age, alfentanil plasma concentration at laryngoscopy) was tested.

METHODS

Eighty-four healthy individuals were randomly assigned to receive one of the seven assessor-blinded alfentanil doses (0, 10, 20, 30, 40, 50 and 60 μg/kg) in conjunction with thiopental 4 mg/kg and rocuronium 0.6 mg/kg. For drug administration, 15 s was allowed. Laryngoscopy was initiated 40 s after rocuronium and tracheal intubation concluded within 70 s after commencement of drug administration. Alfentanil doses associated with 50%, 90% and 95% probability of perfect intubation conditions were determined with logistic regression. Multiple logistic regressions were used to test the influence of covariates. The relationship between alfentanil dose and concentration at laryngoscopy was analysed with linear regression. The effects of covariates on plasma concentrations of alfentanil were tested with multiple linear regressions.

RESULTS

Perfect intubation conditions of 95% probability was obtained with 56 μg/kg (confidence intervals 44-68). None of the covariates were significant predictors of perfect intubation conditions. Alfentanil plasma concentration correlated with dose and increased with increasing body weight (1.7 ng/ml/kg).

CONCLUSION

Perfect intubation conditions during rapid sequence induction can be obtained with clinically relevant doses of alfentanil in most healthy patients anaesthetized with thiopental 4 mg/kg and rocuronium 0.6 mg/kg.

Comparison of cardiac output and hemodynamic responses of intubation among different videolaryngoscopies in normotensive and hypertensive patients

Tracheal intubation with Macintosh laryngoscope (MAC) might result in severe cardiovascular complications. The results of conducted studies investigating the effects of videolaryngoscopies on hemodynamic response of tracheal intubation are conflicting. We know little about the effects of videolaryngoscopies on cardiac output changes during tracheal intubation. We compared cardiac output (COP) and hemodynamic responses in normal blood pressure (n=60) and hypertensive patients (n=60) among 3 intubation devices: the MAC, the UE videolaryngoscopy ® (UE), and the UE video intubation stylet ® (VS). Cardiac index (CI), stroke volume index (SVI), heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded using LidcoRapid (V2)® preinduction, preintubation, and every minute for the first 5 min after intubation. We assessed oropharyngeal and laryngeal structures injury as well. Intubation time was significantly shorter than MAC groups (P<0.001) only in UE group of normotensive and hypertensive patients. In normotensive patients, there were no significant differences in any of COP variables or hemodynamic variables among the three devices. In hypertensive patients, SBP and DBP in the MAC group were significantly higher (P<0.05 or <0.01) than the UE and VS groups at 1, 2 and 3 min after intubation, but there were no significant differences in CI, SVI and HR among the three devices. There was no significant difference in oropharyngeal and laryngeal structures injury among all groups. It was concluded that both the UE and VS attenuate only the hemodynamic response to intubation as compared with the MAC in hypertensive patients, but not in normotensive patients.

"Comparative efficacy of different doses of fentanyl on cardiovascular responses to laryngoscopy and tracheal intubation"

BACKGROUND

This study was conducted to determine an effective bolus dose of fentanyl, which would attenuate the cardiovascular response to laryngoscopy and tracheal intubation.

MATERIALS AND METHODS

A randomised double blind controlled study was carried out on 50 healthy adult patients (ASA I and II) undergoing elective surgery under general anaesthesia. The patients were randomly allocated into two groups of 25 each i.e. group A and group B receiving fentanyl 3 μg/kg, 5 μg/kg intravenously three minutes before intubation respectively. The pulse rate, systolic blood pressure was recorded at induction, during intubation and at 1,3, 5 min post intubation.

RESULTS

The study showed that both the doses were equally effective in blunting the pulse rate response, but the 5μg /kg proved significantly effective in blunting the blood pressure response. The rate pressure product, a measure of cardiac O2 consumption was found to be significantly lower in fentanyl 5μg/kg compared to fentanyl 3μg/kg.

CONCLUSION

So, we conclude that both blood pressure and rate pressure product were completely abolished by a bolus dose of fentanyl 5μg /kg in comparison with fentanyl 3μg/kg following laryngoscopy and intubation.

Oral clonidine versus gabapentin as premedicant for obtunding hemodynamic response to laryngoscopy and tracheal intubation

BACKGROUND

We compared the effects of oral clonidine and gabapentin as premedicant in obtunding hemodynamic response to laryngoscopy and intubation in normotensive patients undergoing elective surgery.

METHODS

A total of 100 patients of either sex enrolled in the study were randomly divided into two groups of 50 each. Group A patients received oral clonidine 200 μg and Group B patients received oral gabapentin 900 mg, 90 min prior to induction of anesthesia.

RESULTS

Both groups were matched for age, sex weight and intubation time. Anxiety score and sedation scores before induction were significantly better in Group A as compared with Group B. Heart rate rise was obtunded in Group A except at 1 min, as compared with Group B in which tachycardia persisted even at 3 and 5 min following intubation. Mean arterial pressure was maintained below baseline at all times in Group A as compared with Group B in which significant rise (+7.55%, P < 0.001) was seen at 1 min after intubation.

CONCLUSION

Oral clonidine provided good attenuation of hemodynamic response to laryngoscopy and intubation as compared with oral gabapentin.

Comparison of the effects of remifentanil andalfentanil on cardiovascular response to nasotracheal intubation: A prospective, randomized, double-blind study

BACKGROUND

Nasotracheal intubation is often necessary in patients undergoingelective or emergency maxillofacial surgery. Previous studies have suggested that the increase in blood pressure after nasotracheal intubation is significantly greater than the increase after orotracheal intubation. Many drugs, including narcotic analgesics, are effective in modifying cardiovascular responses to orotracheal intubation.

OBJECTIVE

The effects of remifentanil and alfentanil on the cardiovascularresponses to nasotracheal intubation were compared in healthy patients scheduled to undergo surgery.

METHODS

This prospective, randomized, double-blind study was conductedat the Department of Anesthesiology and Reanimation, Faculty of Medicine, Dicle University, Diyarbakir, Turkey. Patients aged 16 to 65 years scheduled to undergo elective maxillofacial surgery and who were American Society of Anesthesiologists status I or 11 were randomly assigned to receive remifentanil 1 μg/kg in 10 mL saline over 30 seconds followed by an infusion of 0.5 μg/kg · min, or alfentanil 10 μg/kg in 10 mL saline over 30 seconds followed by an infusion of saline. Anesthesia was then induced with propofol, cisatracurium, and 1% isoflurane with 66% nitrous oxide in oxygen. Heart rate (HR) and systolic and diastolic arterial pressures (SAP and DAP, respectively) were measured noninvasively at 2 minutes before general anesthesia induction (baseline); 2 minutes after induction; and 1, 3, and 5 minutes after nasotracheal intubation. Patients were monitored for cardiac changes using electrocardiography.

RESULTS

Forty consecutive patients were enrolled in the study. Twenty patients (11 males, 9 females; mean [SD] age, 27.7 [12.6] years) received remifentanil, and 20 patients (12 males, 8 females; mean [SD] age, 31.5 [17.2] years) received alfentanil. Two minutes after anesthesia induction, mean (SD) arterial pressures decreased significantly from baseline in the remifentanil group (changes, 22 [8]/11 [6] mm Hg) and the alfentanil group (changes, 10 [9]/12 [8] mm Hg) (both, P < 0.05). Changes in SAP and DAP followed a similar pattern in both groups, but SAP was significantly lower in the remifentanil group compared with that in the alfentanil group throughout the study period (all, P < 0.05). After 1 minute of intubation, DAP was significantly lower in the remifentanil group compared with that in the alfentanil group (66 [9] mm Hg vs. 73 [20] mm Hg; P < 0.05). Compared with baseline, HR was decreased significantly in both groups throughout the study (all, P < 0.05). Except SAP in the alfentanil group, SAP, DAP, and HR were increased 1 minute after intubation compared with preintubation values. However, SAP, DAP, and HR remained significantly lower compared with baseline values throughout the study period in both groups (all, P < 0.05) except DAP at 1 minute after incubation in the alfentanil group. Five patients in the remifentanil group and 2 patients in the alfentanil group required treatment of hypotension. None of the patients in either group required treatment of bradycardia.

CONCLUSIONS

In this study in healthy surgical patients aged 16 to 65 years, remifentanil 1 μg/kg given over 30 seconds, followed by a remifentanil infusion of 0.5 μg/kg · min, was similarly effective compared with alfentanil 10 μg/kg in attenuating the pressor response to nasotracheal intubation, but the incidence of hypotension in patients administered remifentanil was high.

Pretreatment of magnesium sulphate improves intubating conditions of rapid sequence tracheal intubation using alfentanil, propofol, and rocuronium - a randomized trial

Background

We investigated the effects of a magnesium sulfate pretreatment on intubating conditions and cardiovascular responses during rapid sequence tracheal intubation (RSI) in this double-blind randomized study.

Methods

Adult patients (n = 154) were randomly allocated to a rocuronium-0.6, rocuronium-0.9, or magnesium group. The magnesium group was pretreated with 50 mg/kg MgSO₄, and the other two groups received the same volume of isotonic saline. Anesthesia was induced with alfentanil, propofol, and either 0.6 mg/kg (rocuronium-0.6 and magnesium groups) or 0.9 mg/kg (rocuronium-0.9 group) rocuronium. An anesthesiologist, blinded to the group assignments, performed RSI and assessed the intubating conditions. Systolic arterial pressure (SAP) and heart rate (HR) were recorded before the magnesium sulfate or normal saline was administered, before anesthesia induction, before intubation, and every minute after intubation for 5 min.

Results

Airway features were similar among the three groups. The intubating conditions were improved significantly in the magnesium group (P < 0.001) compared with the other two groups. Significant increases in SAP at 1 min after intubation were observed in the rocuronium-0.6 and -0.9 groups when compared with the magnesium group (P < 0.05). HR was comparable among the three groups (P > 0.05). No hypertensive episode occurred during the immediate post-intubation period in the magnesium group (P = 0.001), and tachycardia occurred most frequently in the rocuronium-0.6 group (P < 0.05).

Conclusions

MgSO₄ administered prior to RSI using alfentanil, propofol, and rocuronium may improve intubating conditions and prevent post-intubation hypertension.

Comparison of target-controlled infusion of sufentanil and remifentanil in blunting hemodynamic response to tracheal intubation

Background:

Maintaining blood pressure (BP) and heart rate (HR) after laryngoscopy and tracheal intubation has always been a concern in injured patients. Opioids can attenuate or stop an increase in these two parameters if administered with proper doses or targets in target-controlled infusion (TCI). Remifentanil and sufentanil are widely used for this purpose because their cardiac side effects are low and, especially in traumatic patients, they are tolerated well. A comparison of the benefits and limitations of these two opioids in TCI is much needed. A literature review in electronic data bases revealed few results.

Methods:

40 normotensive patients were enrolled to this randomized clinical trial study. After BIS guided anesthesia with a target-controlled propofol infusion and muscle relaxation with cisatracurium, remifentanil and sufentanil were infused using TCI with 2 and 0.2 ng.ml-1 targets respectively. BP and HR were recorded for five data points and compared with Fischer's exact test.

Results:

Systolic, mean and diastolic arterial pressure and HR in different points of the study remained below baseline values but were out of control in some cases, however the out-of-control values showed significant difference between the two groups only for heart rate changes. The relative risk for producing out-of-control changes with remifentanil compared to sufentanil is significantly more than 1 for HR decrease.

Conclusions:

Sufentanil produced more common pre-intubation hypotension than remifentanil in propofol anesthetized patients but this hypotension disappeared sooner than remifentanil after tracheal intubation. Both opioids prevent an increase in BP and HR after tracheal intubation but the side effects (hypotension and bradycardia) may be a cause for concern (IRCT138710011361N3).

Optimal fentanyl dosage for attenuating systemic hemodynamic changes, hormone release and cardiac output changes during the induction of anesthesia in patients with and without hypertension: a prospective, randomized, double-blinded study

PURPOSE

The purpose of this study was to compare the dose-related effects of fentanyl on systemic hemodynamics, hormone release and cardiac output in response to endotracheal intubation in patients with and without hypertension.

METHODS

Forty-five patients without hypertension and 45 patients with hypertension (total 90 patients) undergoing elective general surgical, urological or gynecological procedures under general anesthesia were studied. The patients were randomly divided into three groups to receive either saline (control), 2.0 μg/kg fentanyl or 4.0 μg/kg fentanyl before tracheal intubation. Anesthesia was induced via intravenous target controlled infusion of propofol (plasma concentration, 4.0 μg/mL) followed by administration of the three drugs. Heart rate, blood pressure, and cardiac output were continuously monitored using Flo Trac/Vigileo system™ and Bispectral index from before anesthetic induction until 10 min after tracheal intubation.

RESULTS

In patients without hypertension, there was a significant difference in mean arterial pressure (MAP) among the three groups 2 min after intubation. Cardiac index (CI) in all three groups decreased before intubation compared with that in the awake period, returning to awake values after intubation in all three groups. There was a significant difference in CI between the 4 μg/kg fentanyl group and the other two groups immediately and 1 min after intubation. In patients with hypertension, a differential time course of MAP changes was observed among the three groups after intubation. CI in the three groups decreased after the induction of anesthesia and increased after intubation in control and 2 μg/kg fentanyl groups compared with that in the awake period.

CONCLUSIONS

The present study shows that it is preferable to administer 2 μg/kg fentanyl in patients without hypertension and 4 μg/kg fentanyl in patients with hypertension in order to minimize the changes in heart rate, systolic blood pressure and cardiac output associated with tracheal intubation.

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.

Adequate sevoflurane concentrations in inhalation induction of sevoflurane following administration of remifentanil

BACKGROUND

Currently, sevoflurane and remifentanil are utilized frequently for the inhalation induction of anesthesia. However, there is currently an insufficient amount of clinical data regarding the inhalation induction of sevoflurane after the administration of remifentanil.

METHODS

80 patients undergoing elective surgery were allocated randomly to four groups. Group A inhaled only sevoflurane at 8 vol%. Other groups were administered 3 ng/ml of remifentanil and inhaled sevoflurane at 8 vol% (group B) or 6 vol% (group C) or 4 vol% (group D). All groups also received 0.6 mg/kg of rocuronium. The blood pressure and heart rate were measured at pre-induction, and before and after tracheal intubation. After operation, the patients??levels of satisfaction with the inhalation induction were evaluated.

RESULTS

The time to loss of consciousness was substantially longer in group D than in the other groups, but no significant differences were noted among the groups in terms of satisfaction scores. The HR in groups B, C and D increased significantly after pre-intubation as compared to baseline in group A. The HR decreased significantly during induction as compared to group A. The MAP in groups B, C and D decreased significantly at 1 and 2 minutes after tracheal intubation as compared to group A. In group D only, we noted no significant differences in the MAP as compared to baseline at 1, 2 minutes after tracheal intubation.

CONCLUSIONS

4 vol% sevoflurane was a more appropriate concentration for the inhalation induction of anesthesia when coupled with 3 ng/ml of remifentanil.

Dose of alfentanil needed to obtain optimal intubation conditions during rapid-sequence induction of anaesthesia with thiopentone and rocuronium

BACKGROUND

The primary aim of the present study was to determine the dose of alfentanil that must be added to a rapid-sequence induction (RSI) regimen using thiopentone and rocuronium to obtain optimal intubation conditions in >95% of the individuals.

METHODS

A total of 60 ASA I patients were randomly allocated to five different alfentanil dose groups (0, 15, 30, 45, or 60 microg kg-1). A blinded dose of alfentanil followed by thiopentone 4 mg kg-1 and rocuronium 1 mg kg-1 was administered in rapid succession, and tracheal intubation was attempted 40 s thereafter. The relationship between the alfentanil dose and the probability of optimal intubation conditions was determined by non-linear logistic regression analysis. Blood pressure (BP) changes were recorded continuously using an intra-arterial catheter.

RESULTS

The success rate of optimal intubation conditions increased with increasing doses of alfentanil. The alfentanil dose needed to obtain optimal intubation conditions in >95% of the patients was 36.4 (CI 33.4-39.4) microg kg-1. In 12 patients, the systolic BP declined to <90 mm Hg during the 3 min immediately after intubation.

CONCLUSION

Adding 36-40 microg kg-1 alfentanil to a regimen of thiopentone and rocuronium during RSI of anaesthesia may significantly increase the success rate of optimal intubation conditions. Significant hypotension requiring vasopressor treatment may occur.

Alfentanil attenuates phenylephrine-induced contraction in rat aorta

BACKGROUND AND OBJECTIVES

Alfentanil was reported to relax the rat aorta by direct action on the vascular smooth muscle. The aims of this in vitro study were to examine the effect of alfentanil on phenylephrine-induced contractions in the rat aorta and to determine the cellular mechanism associated with this process.

METHODS

Endothelium-denuded aortic rings were suspended in order to record isometric tension. In the rings with or without 10(-6) mol naloxone or 10(-5) mol verapamil, the concentration-response curves for phenylephrine and potassium chloride were generated in the presence or absence of alfentanil (10(-6), 5 x 10(-5), 10(-4) mol). In the rings exposed to a calcium-free isotonic depolarizing solution, the contractile response induced by the addition of calcium was assessed in the presence or absence of alfentanil (5 x 10(-5), 10(-4) mol).

RESULTS

Alfentanil (5 x 10(-5), 10(-4) mol) attenuated (P < 0.05) the phenylephrine-induced contraction in the ring with or without 10(-6) mol naloxone but had no effect on the phenylephrine-induced contraction in the rings pretreated with verapamil. Alfentanil (5 x 10(-5), 10(-4) mol) produced a significant rightward shift (P < 0.01) in the potassium chloride dose-response curve, and attenuated the contractile response (P < 0.001) induced by calcium in the calcium-free isotonic depolarizing solution in a dose-dependent manner.

CONCLUSIONS

A supraclinical dose of alfentanil attenuates the phenylephrine-induced contraction via an inhibitory effect on calcium influx by blocking the l-type calcium channels in the rat aortic vascular smooth muscle.

Gabapentin attenuates the pressor response to direct laryngoscopy and tracheal intubation

BACKGROUND

Laryngoscopy and tracheal intubation increase blood pressure and heart rate (HR). The aim of the present study was to investigate the effect of gabapentin when given before operation on the haemodynamic responses to laryngoscopy and intubation.

METHODS

Forty-six patients undergoing abdominal hysterectomy for benign disease were randomly allocated to receive gabapentin 1,600 mg or placebo capsules at 6 hourly intervals starting the day (noon) before surgery. Anaesthesia was induced with propofol and cis-atracurium. Systolic, diastolic arterial blood pressures (SAP, DAP) and heart rate (HR) were recorded before and after the anaesthetic and 0, 1, 3, 5 and 10 min after tracheal intubation.

RESULTS

SAP was significantly lower in the gabapentin vs the control group 0, 1, 3, 5 and 10 min after intubation [128 (27) vs 165 (41), P=0.001, 121 (14) vs 148 (29), P=0.0001, 115 (13) vs 134 (24), P=0.002, 111 (12) vs 126 (19), P=0.004 and 108 (12) vs 124 (17), P=0.001 respectively]. DAP also was lower in the gabapentin group 0, 1, 3, and 10 min after intubation [81 (18) vs 104 (19), P=0.0001, 77 (9) vs 91 (16), P=0.001, 71 (10) vs 84 (13), P=0.001 and 67 (10) vs 79 (12), P=0.004]. HR did not differ between the two groups at any time [82 (11) vs 83 (15), 79 (10) vs 80 (12), 86 (17) vs 92 (10), 82 (11) vs 88 (10), 81 (12) vs 81 (11), 77 (13) vs 79 (13), and 75 (15) vs 78 (12)].

CONCLUSION

Gabapentin, under the present study design attenuates the pressor response but not the tachycardia associated with laryngoscopy and tracheal intubation.

Intubation conditions after rocuronium or succinylcholine for rapid sequence induction with alfentanil and propofol in the emergency patient

BACKGROUND AND OBJECTIVE

Previous studies mainly conducted on elective patients recommend doses of 0.9-1.2 mg kg[-1] rocuronium to obtain comparable intubation conditions with succinylcholine 1.0 mg kg[-1] after 60 s during a rapid-sequence induction. We decided to compare the overall intubating conditions of standard doses of rocuronium 0.6 mg kg[-1] and succinylcholine 1.0 mg kg[-1] during a strict rapid-sequence induction regimen including propofol and alfentanil.

METHODS

Male and female patients (ASA I-III) older than 17 yr scheduled for emergency abdominal or gynaecological surgery and with increased risk of pulmonary aspiration of gastric content were randomized to a rapid-sequence induction with succinylcholine 1.0 mg kg[-1] or rocuronium 0.6 mg kg[-1]. Patients with a predicted difficult airway were excluded. A senior anaesthesiologist 'blinded' for the randomization performed the intubation 60 s after injection of the neuromuscular blocker. Intubating conditions were evaluated according to an established guideline. Tracheal intubation not completed within 30 s was recorded as failed.

RESULTS

222 patients were randomized. Three patients had their operation cancelled and 10 did not fulfil the inclusion criteria. Clinically acceptable intubation conditions were present in 93.5% and 96.1% of patients in the succinylcholine group (n=107) and the rocuronium group (n=102), respectively (P=0.59).

CONCLUSIONS

During a rapid-sequence induction with alfentanil and propofol, both rocuronium 0.6 mg kg[-1] and succinylcholine 1.0 mg kg[-1] provide clinically acceptable intubation conditions in 60 s in patients scheduled for emergency surgery. Under the conditions of this rapid-sequence induction regimen rocuronium may be a substitute for succinylcholine.

Double-blind placebo controlled study of the effects of etomidate-alfentanil anesthesia in electroconvulsive therapy

The effect of etomidate and alfentanil on heart rate, systolic arterial pressure, diastolic arterial pressure, and mean arterial pressure was compared with etomidate and placebo during electroconvulsive therapy (ECT). We also studied the influence of alfentanil on seizure duration using both the cuff method and 2-lead electroencephalographs on the prevention of myoclonus induction by etomidate, on duration of apnea and on postictal agitation after ECT. We enrolled 21 consecutive patients in a prospective placebo-controlled, within patient blocked randomized study. Alfentanil significantly reduced heart rate, diastolic arterial pressure, and mean arterial pressure both before and after the stimulus. The increase in these variables during the convulsion was not affected, compared with placebo. Alfentanil had no effect on seizure duration. However, apnea duration was prolonged during the alfentanil sessions as compared with placebo (73 seconds). Alfentanil did not significantly reduce the occurrence of myoclonus after etomidate as compared with placebo, nor did postictal agitation after ECT appear more often with alfentanil. Alfentanil could be useful to reduce tachycardia and hypertension during ECT in high-risk patients without effects on seizure duration. Alfentanil itself has no proconvulsive effect in combination with etomidate.

Effects of remifentanil and alfentanil on the cardiovascular responses to induction of anaesthesia and tracheal intubation in the elderly

BACKGROUND

We compared the effects of remifentanil and alfentanil on arterial pressure and heart rate at induction of anaesthesia and tracheal intubation in 40 ASA I-III patients aged greater than 65 yr, in a randomized double-blind study.

METHODS

Patients received either remifentanil 0.5 microg kg(-1) over 30 s, followed by an infusion of 0.1 microg kg min(-1) (group R) or alfentanil 10 microg kg(-1) over 30 s, followed by an infusion of saline (group A). Anaesthesia was then induced with propofol, rocuronium, and 1% isoflurane with 66% nitrous oxide in oxygen.

RESULTS

Systolic arterial pressure (SAP) and mean arterial pressure (MAP) decreased after the induction of anaesthesia (P<0.05) and increased for 3 min after intubation in both groups (P<0.05), but remained below baseline values throughout. Heart rate remained stable after induction of anaesthesia but increased significantly from baseline after intubation for 1 and 4 min in groups R and A, respectively (P<0.05). There were no significant between-group differences in SAP, MAP, and heart rate. Diastolic pressure was significantly higher in group A than group R at 4 and 5 min after intubation (P<0.05). Hypotension (SAP < 100 mm Hg) occurred in four patients in group R and three patients in group A.

CONCLUSIONS

Remifentanil and alfentanil similarly attenuate the pressor response to laryngoscopy and intubation, but the incidence of hypotension confirms that both drugs should be used with caution in elderly patients.

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.

Comparison of the effects of intravenous alfentanil and esmolol on the cardiovascular response to double-lumen endobronchial intubation

We compared the effect of alfentanil 10 microg.kg-1 and esmolol 1.5 mg.kg-1 on the cardiovascular responses to laryngoscopy and double-lumen endobronchial intubation in two groups of 20 ASA 2-3 patients undergoing pulmonary surgery, in a randomised double-blind study. Arterial pressure and heart rate decreased after induction of anaesthesia and increased after intubation in both groups (p < 0.05) but remained at or below baseline values, and changes were comparable in both groups. Plasma catecholamine concentrations decreased after induction of anaesthesia in both groups (p < 0.05). Epinephrine concentrations increased in the esmolol group after intubation (p < 0.05) but remained below baseline in the alfentanil group (p < 0.05). Norepinephrine concentrations increased significantly in both groups after intubation but were higher in the esmolol group (p < 0.05). Although both esmolol 1.5 mg.kg-1 and alfentanil 10 microg.kg-1 similarly attenuated the arterial pressure and heart rate response to endobronchial intubation, plasma catecholamine concentrations increased in the esmolol group to values greater than previously reported after tracheal intubation.