Haemodynamic responses to laryngoscopy and tracheal intubation in geriatric patients: effects of fentanyl, lidocaine and thiopentone

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

Objectives

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

Materials and Methods

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

Results

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

Conclusion

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

Cerebral blood flow changes during palpation of external airway structures in healthy volunteers

Introduction

Previous studies demonstrate increased intracranial pressure (ICP) during direct laryngoscopy in patients with traumatic brain injury (TBI). Worse outcomes in TBI have been associated with increased ICP. It remains unclear if the same effect occurs during cricothyrotomy. We evaluated changes in cerebral blood flow and hemodynamic changes that occurred during preparation for cricothyrotomy in healthy volunteers.

Methods

An emergency medicine trainee performed routine anatomical procedural palpation with simultaneous transcranial doppler (TCD) measurements of cerebral blood flow velocities (CBFV) from bilateral middle cerebral arteries (MCAs). Mean arterial pressure (MAP) and heart rate (HR) were recorded throughout event. Our primary outcome was changes in pulsatility index (PI) and CBFV by TCD during palpation. TCD measurements were used as a surrogate for ICP.

Results

We enrolled 20 healthy volunteers for this study. No significant differences were found in pulsatility index [Right MCA -0.02 (95% confidence interval, -0.09 to 0.06), left MCA -0.02 (95% confidence interval, -0.011 to 0.07)] or mean CBFV [right MCA -0.70 mm/s (95% confidence interval, -10.15 to 8.75) left MCA -1.20 mm/s (95% confidence interval, -10.68 to 8.28)] during palpation. No significant change in HR was found [-1.1 bpm ((95% confidence interval, -2.4 to 0.1)]. A change in MAP was observed [1.3 mmHg (95% confidence interval, -0.1 to 2.4)].

Conclusions

In healthy individuals, no clinically significant change in cerebral blood flow velocities, ICP, or change heart rate was observed during palpation for cricothyrotomy.

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.

Preoperative Low-dose and High-dose Pregabalin and Cardiovascular Response to Endotracheal Intubation: A Prospective, Randomized, Single-blind, Controlled Study in China

PURPOSE

A prospective, randomized, single-blind, controlled clinical study was designed to evaluate the efficacy and tolerability of preoperative pregabalin on cardiovascular response to laryngoscopy and endotracheal intubation.

METHODS

Patients aged 18-60 years with an American Society of Anesthesiologists scale score of I or II were recruited and randomly allocated to receive placebo (control), low-dose (150-mg) pregabalin, or high-dose (300-mg) pregabalin. The medications were orally administered 1 hour before general anesthesia. Heart rate, systolic and diastolic blood pressures, and mean arterial blood pressure were measured and recorded prior to the administration of placebo or pregabalin; before endotracheal intubation; and at 0, 1, 3, 5, 7, and 10 minutes after intubation. The sedation score was evaluated 1 hour after the administration of placebo or pregabalin.

FINDINGS

A total of 90 patients were enrolled (n = 30 per group). Pregabalin (150 or 300 mg) was associated with reduced blood pressure fluctuations after intubation, but with no significant differences between the 2 dose groups. Pregabalin was associated with an inhibitory effect on heart rate fluctuations and reduced hemodynamic complications after intubation, in a dose-dependent manner, but no effect on the required perioperative opioid dosage was found. Both doses were effective in reducing preoperative anxiety, but visual analog scale pain scores at 1 hour after surgery were reduced only in limb and spine as well as abdominal surgeries. A pregabalin-related adverse reaction was dizziness, which was observed at 1 hour after surgery in both groups.

IMPLICATIONS

In this study, high-dose (300-mg) pregabalin effectively attenuated cardiovascular response after endotracheal intubation. ClinicalTrials.gov identifier: NCT03456947.

Effects of Intravenous and Inhaled Nebulized Lignocaine on the Hemodynamic Response of Endotracheal Intubation Patients: A Randomized Clinical Trial

Background

Endotracheal intubation is one of the most common measures in the Intensive Care Unit (ICU) which plays an important role in airway management of the critically ill patients.

Aims

The study aimed to evaluate the effects of lignocaine spray on hemodynamic response of endotracheal intubation patients.

Settings and Design

This study is a randomized clinical trial on a study population comprising patients admitted to the ICU.

Subjects and Methods

The patients were divided into three groups using a permuted block randomization. In Group 1, inhaled nebulized lignocaine 4% (75.0 mg/kg) was sprayed around the patients' epiglottis and larynx. In Group 2, intravenous (IV) lignocaine 2% (75.0/mg/kg) was injected. No lignocaine was prescribed for or administered to the control group. One and four minutes after intubation, the patients' hemodynamic and vital signs were measured.

Statistical Analysis Used

Data analysis was run using Stata 13 software through repeated measure ANOVA tests.

Results

Although the mean arterial blood pressure (MAP) of Group 1 (inhaled nebulized lignocaine) was smaller than that of Group 2 (IV lignocaine), there was no significant difference between the two groups. Both groups' MAPs were significantly different from that of the control group. As for the average number of pulses, a significant difference was observed between the inhaled and IV lignocaine groups; hence, the average number of pulses in Group 1 (inhalation) was lower than that of Group 2 (IV injection).

Conclusion

As blood pressure is considered to be normal under 140/90 and may not entail any hemodynamic complications, it can be concluded that inhaled nebulized lignocaine can control the hemodynamic changes of intubation more effectively than IV lignocaine.

Effects of intravenous administration of fentanyl and lidocaine on hemodynamic responses following endotracheal intubation

OBJECTIVES

To compare the effects of intravenous fentanyl and lidocaine on hemodynamic changes following endotracheal intubation in patients requiring Rapid Sequence Intubation (RSI) in the emergency department (ED).

METHODS

A single-centered, prospective, simple non-randomized, double-blind clinical trial was conducted on 96 patients who needed RSI in Edalatian ED. They were randomly divided into three groups (fentanyl group (F), lidocaine group (L), and fentanyl plus lidocaine (M) as our control group). M was administered with 3 μgr/kg intravenous fentanyl and 1.5 μgr/kg intravenous lidocaine, F was injected with 3g/kg intravenous fentanyl and L received 1.5mg/kg intravenous lidocaine prior to endotracheal intubation. Heart rate (HR) and mean arterial pressure (MAP) were assessed four times with the chi-square test: before, immediately after, 5 and 10 min after intubation. Intervention was discontinued for five people due to unsuccessful CPR.

RESULTS

HR was notably different in F, L and M groups during four time courses (p<0.05). Comparison of MAP at measured points in all groups exhibited no significant difference (p>0.05). In fentanyl group both HR and MAP increased immediately after intubation, and significantly decreased 10 min after intubation (p<0.05).

CONCLUSIONS

Overall, the result of this study shows that lidocaine effectively prevents MAP and HR fluctuations following the endotracheal intubation. According to our findings, lidocaine or the combination of fentanyl and lidocaine are able to diminish hemodynamic changes and maintain the baseline conditions of the patient, thus could act more effectively than fentanyl alone.

"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.

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

CONTEXT

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

AIMS

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

SETTINGS AND DESIGN

This was a prospective randomized double-blind control study.

SUBJECTS AND METHODS

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

STATISTICAL ANALYSIS USED

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

RESULTS

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

CONCLUSIONS

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

Pharmacological agents for preventing morbidity associated with the haemodynamic response to tracheal intubation

BACKGROUND

Several drugs have been used in attenuating or obliterating the response associated with laryngoscopy and tracheal intubation. These changes are of little concern in relatively healthy patients but can lead to morbidity and mortality in the high risk patient population.

OBJECTIVES

The primary objective of this review was to determine the effectiveness of pharmacological agents in preventing the morbidity and mortality resulting from the haemodynamic changes in response to laryngoscopy and tracheal intubation in adult patients aged 18 years and above who were undergoing elective surgery in the operating room setting.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 6), MEDLINE (1950 to June 2011), EMBASE (1980 to June 2011), and the bibliographies of published studies. We reran our search from June 2011 to December 2012 and will deal with these studies when we update the review.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared a drug used as an intervention for preventing or attenuating the haemodynamic response to tracheal intubation to a control group, and that mentioned mortality, major morbidity, arrhythmia or electrocardiogram (ECG) evidence of ischaemia in the methodology, results, or discussion section of the reports.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted the outcome data.

MAIN RESULTS

We included 72 RCTs. The included trials studied the effects of 32 drugs belonging to different pharmacological groups. Only two trials mentioned the primary outcome of morbidity and mortality related to the haemodynamic response to tracheal intubation. Of the secondary outcomes, 40 of the included trials observed arrhythmia only, 11 observed myocardial ischaemia only and 20 observed both arrhythmias and myocardial ischaemia. Arrhythmias were observed in 2932 participants and myocardial ischaemia in 1616 participants. Arrhythmias were observed in 134 out of 993 patients in the control group compared to 80 out of 1939 in the intervention group. The risk of arrhythmias was significantly reduced with pharmacological interventions in the pooled data (Peto odds ratio (OR) 0.19, 95% CI 0.14 to 0.26, P < 0.00001, I(2)= 47%). Local anaesthetics, calcium channel blockers, beta blockers and narcotics reduced the risk of arrhythmia in the intervention group compared to the control group. Myocardial ischaemia was observed in 21 out of 604 patients in the control group compared to 10 out of 1012 in the treatment group; the result was statistically significant (Peto OR 0.45, 95% CI 0.22 to 0.92, P = 0.03, I(2) = 19%). However, in subgroup analysis only local anaesthetics significantly reduced the ECG changes indicating ischaemia, but this evidence came from one study. The majority of the studies had a negative outcome. Hypotension and bradycardia were reported with 40 µg kg(-1) intravenous alfentanil, chest rigidity with 75 ug kg(-1) alfentanil, and increased bronchomotor tone with sympathetic blockers.There were 17 studies which included high risk patients. Pharmacological treatment in this group resulted in the reduction of arrhythmias when the data from nine trials looking at arrhythmias were pooled (Peto OR 0.18, 95% CI 0.05 to 0.59, P = 0.005, I(2) = 80%). The analysis from four studies was not included. Three of these trials looked at the effect of sympathetic blockers but arrhythmias or myocardial ischaemia was observed throughout the perioperative period in two studies and some patients had arrhythmias due to atropine premedication in the third study. In the fourth study the authors mentioned myocardial ischaemia in the objectives section but did not report it in the results.

AUTHORS' CONCLUSIONS

The risk of arrhythmias associated with tracheal intubation was significantly reduced with pre-induction administration of local anaesthetics, calcium channel blockers, beta blockers and narcotics compared to placebo. Pharmacological intervention also reduced the risk of ECG evidence of myocardial ischaemia in the pooled data. Lignocaine pretreatment showed a significant effect but evidence came from one study only. The data suggested that there may be a reduction in ECG evidence of myocardial ischaemia with beta blocker pretreatment but this difference was not statistically significant. There is a need to focus on outcomes rather than haemodynamic measurements alone when studying this response in future trials.

Comparison of effects of fentanyl and remifentanil on hemodynamic response to endotracheal intubation and myoclonus in elderly patients with etomidate induction

BACKGROUND

Etomidate has a stable hemodynamic profile after induction, but hypertension and tachycardia are frequent after intubation as well as myoclonus. We compared the effects of fentanyl and remifentanil on the hemodynamic response to intubation and myoclonus during etomidate induction in elderly patients.

METHODS

Ninety ASA I or II patients aged over 65 were randomly assigned to 3 groups. Group C received normal saline 10 ml (n = 30), group F and R were pretreated with fentanyl 1.0 µg/kg (n = 30) or remifentanil 1.0 µg/kg with continuous infusion of 0.1 µg/kg/min (n = 30) 1 min before induction with etomidate 0.2 mg/kg. Endotracheal intubation was performed after administration of rocuronium 0.8 mg/kg. Systolic blood pressure (SBP), mean arterial pressure, diastolic blood pressure (DBP), heart rate (HR), and the incidence and intensity of myoclonus were recorded.

RESULTS

After intubation, group R showed significant decreases compared with groups C and F for all of the hemodynamic variables measured. The incidences of increases in SBP and HR of more than 30% of the baseline levels, SBP of > 200 mmHg, and HR of > 120 beats/min were significantly lower in group R (0%, 10%, 0%, and 0%, respectively) compared with groups C (83%, 83%, 30%, and 13%, respectively) and F (63%, 77%, 13%, and 7%, respectively). The frequency and intensity of myoclonus were significantly decreased in both groups F and R compared with group C.

CONCLUSIONS

Pretreatment with remifentanil suppressed cardiovascular reactions to endotracheal intubation more effectively than that of fentanyl during etomidate induction. Both opioids reduced the incidence of myoclonus.

[Bolus administration of fentanyl vs continuous perfusion of remifentanil for control of hemodynamic response to laryngoscopy and orotracheal intubation: a randomized double-blind trial]

OBJECTIVES

To compare the efficacy and safety of fentanyl and remifentanil in the prevention of hemodynamic responses to direct laryngoscopy and orotracheal intubation, and to compare the effects of these techniques on peripheral blood oxyhemoglobin saturation in normotensive women undergoing scheduled gynecologic surgery.

MATERIAL AND METHODS

Prospective clinical trial in ASA 1-2 patients undergoing gynecologic surgery. The patients were randomized to 2 groups: the remifentanil group received a perfusion of 1 microg x kg(-1) x min(-1) until intubation whereas the fentanyl group received a bolus dose of 2 microg x kg(-1). Etomidate (0.3 mg x kg(-1)) and rocuronium bromide (0.6 mg x kg(-1)) were used for anesthetic induction. Seven serial measurements of systolic, diastolic, and mean arterial pressure were recorded in addition to heart rate and peripheral blood oxyhemoglobin saturation at the following times: baseline, denitrogenation, postinduction, and 3 more times at consecutive 2-minute intervals.

RESULTS

Fifty-four patients were enrolled. A statistically significant attenuation of the postintubation hemodynamic response was observed in the remifentanil group. The effect was evident on arterial pressure (P=.0001) and heart rate (P=.031) with respect to baseline values. That protective effect was not seen in the fentanyl group. No differences in peripheral blood oxyhemoglobin saturation were observed.

CONCLUSIONS

Remifentanil provides greater hemodynamic control than fentanyl at the doses utilized. No adverse effects attributable to these opioids were observed in either group.

Effect of intravenous lidocaine on heart rate, systolic arterial blood pressure and cough responses to endotracheal intubation in propofol-anaesthetized dogs

OBJECTIVE

To evaluate the effect of intravenous lidocaine on coughing and variations in heart rate (HR) and systolic arterial pressure (SAP) at endotracheal intubation in propofol-anaesthetized dogs.

STUDY DESIGN

Prospective, randomized, blinded clinical study.

ANIMALS

Eighty dogs, ASA grades I/II.

METHODS

Dogs were randomly assigned to one of two treatments, with dogs in the lidocaine group receiving 1 mg kg(-1) lidocaine intravenously and those in the saline group receiving 0.05 mL kg(-1) saline intravenously before induction of anaesthesia with up to 6.5 mg kg(-1) propofol intravenously. An electrocardiogram was recorded continuously. Heart rate was calculated and SAP (using Doppler ultrasonic flow detection) was recorded at the following time points: pre-treatment, following lidocaine or saline administration, before and after intubation. The occurrence, number and strength of coughs were recorded. Systolic arterial pressure and HR were compared using one-sample t-tests to examine whether SAP and HR changed with test drug administration or following intubation. The number of coughs was compared between groups using t-tests. A cross tabulation and chi-square or Fisher's exact test was used to compare proportions of dogs that coughed and intensity of coughing in each group. The level of significance was set at p < 0.05.

RESULTS

Heart rate did not change in either group. Systolic arterial blood pressure increased following intubation in both the lidocaine (p = 0.003) and saline groups (p = 0.001). There was no difference in the increase in SAP or in the number or intensity of coughs at intubation between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Intravenous lidocaine had no effect on the occurrence or intensity of coughing or on changes in SAP at endotracheal intubation in dogs anaesthetized with propofol. The use of 1 mg kg(-1) lidocaine intravenously before intubation in dogs to attenuate cough and the pressor response was not supported.

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

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Reflex activity caused by laryngoscopy and intubation is obtunded differently by meptazinol, nalbuphine and fentanyl

BACKGROUND AND OBJECTIVE

To evaluate the different potencies of several opioids in obtunding reflex mechanisms of laryngoscopy and intubation.

METHODS

Three groups of patients (each n = 25, ASA 1-2) undergoing elective plastic surgery were randomly given meptazinol (2.5 mg kg-1), nalbuphine (0.3 mg kg-1) or fentanyl (5 microg kg-1) in a blinded fashion prior to laryngoscopy and intubation. This was followed by a standardized bolus induction of a barbiturate and a muscle relaxant. The response to laryngoscopy and intubation was studied, using blood pressure, heart rate and bispectral index.

RESULTS

With fentanyl, there was an increase of heart rate by 17%, and systolic blood pressure by 7% when compared to control. Bispectral index dropped an additional 8% when compared to 1 min after barbiturate induction. In the nalbuphine group there was a 16% increase in systolic blood pressure, and a 16% increase in heart rate when compared to control. Also, bispectral index increased by 18% when compared to 1 min after barbiturate injection. The group receiving meptazinol demonstrated no cardiovascular changes although bispectral index dropped by an additional 19% when compared to 1 min after barbiturate injection.

CONCLUSION

Meptazinol, appears to depress cardiovascular stimulatory effects and electroencephalogram arousal induced by laryngoscopy and intubation better than nalbuphine or fentanyl.

Should etomidate be the induction agent of choice for rapid sequence intubation in the emergency department?

The ideal induction agent for emergency airway management should be rapidly acting, permit optimum intubating conditions, and be devoid of significant side effects. This review was performed to ascertain whether etomidate should be the induction agent of choice for rapid sequence intubation (RSI) in the emergency department, specifically examining its pharmacology, haemodynamic profile, and adrenocortical effects. A search of Medline (1966-2002), Embase (1980-2002), the Cochrane controlled trials register, and CINAHL was performed. In addition, the major emergency medicine and anaesthesia journals were hand searched for relevant material. Altogether 144 papers were identified of which 16 were relevant. Most studies were observational studies or retrospective reviews with only one double blind randomised controlled trial and one un-blinded randomised controlled trial. Appraisal of the available evidence suggests that etomidate is an effective induction agent for emergency department RSI; it has a rapid onset of anaesthesia and results in haemodynamic stability, even in hypovolaemic patients or those with limited cardiac reserve. Important questions regarding the medium to long term effects on adrenocortical function (even after a single dose) remain unanswered.

Endotracheal intubation with a lightwand or a laryngoscope results in similar hemodynamic variations in patients with coronary artery disease

PURPOSE

To asses the cardiovascular changes after either lightwand or conventional laryngoscopic endotracheal intubation (EI) in patients with coronary artery disease.

METHODS

Following Institutional approval and informed consent, 80 consecutive patients undergoing elective coronary artery bypass grafting were enrolled in this prospective, controlled, single-blinded study. General anesthesia was induced with fentanyl 5 micro x kg(-1) and thiopental 5 mg x kg(-1) followed by pancuronium 0.1 mg x kg(-1). After loss-of-eyelash reflex the lungs were manually ventilated with 2% isoflurane in oxygen for five minutes. Patients were then randomly allocated to receive either the lightwand (lightwand group, n = 41) or direct-vision laryngoscopy (laryngoscopy group, n = 39). Heart rate (HR) and direct blood pressure were recorded before induction, after induction but before EI, during EI, immediately after EI and at ten-second intervals for the following five minutes. Hemodynamic management during induction was standardized. Hypotension was treated with volume replacement, ephedrine, or phenylephrine as indicated; hypertension was treated with iv nitroglycerin; tachycardia was treated with boluses of esmolol; and, bradycardia was treated with atropine or ephedrine.

RESULTS

In both groups, mean arterial blood pressures and HR increased significantly after EI. There was a tendency for the lightwand group to have lower arterial blood pressures and slower HR. However, the differences between the two groups did not reach statistical significance. Requirements for drugs to control HR and mean arterial pressure were similar in both groups.

CONCLUSION

In patients with coronary artery disease using a lightwand intubation technique does not modify the hemodynamic response associated with EI as compared with standard direct-vision laryngoscopy.

Effect-site concentration of propofol for recovery of consciousness is virtually independent of fentanyl effect-site concentration

Fentanyl reduces the amount of propofol necessary to prevent responses to surgical stimuli. However, opioids have relatively little effect on consciousness. We, therefore, tested the hypothesis that fentanyl minimally alters the effect-site concentration of propofol associated with awakening. Fifty women having gynecologic laparotomy with propofol anesthesia were randomly allocated into the following target effect-site fentanyl concentrations: 0.8, 1.0, 1.4, 2.0, and 3.0 ng/mL. Fentanyl was continued at the designated rate through the initial postoperative phase. The propofol effect-site concentration associated with eye opening in response to verbal command was regarded as the awakening concentration. The estimated propofol effect-site concentrations at awakening did not differ significantly among the groups and were 1.9 +/- 0.5 micro g/mL with a fentanyl effect-site concentration of 0.8 ng/mL; 1.6 +/- 0.4 micro g/mL with 1.0 ng/mL of fentanyl; 1.6 +/- 0.2 micro g/mL with 1.4 ng/mL of fentanyl; 1.7 +/- 0.4 micro g/mL with 2.0 ng/mL of fentanyl; and 1.6 +/- 0.34 micro g/mL with 3.0 ng/mL of fentanyl (mean +/- SD). Seventy percent of the subjects in the 0.8 ng/mL fentanyl group spontaneously complained of pain, whereas none of the patients in the 2 or 3 ng/mL groups did. Five (56%) of 9 women in the 3 ng/mL group had a postoperative respiratory rate <6 breaths/min. Heart rate in one of these women decreased to <40 bpm. These data suggest that the optimal fentanyl effect-site concentration in patients recovering from gynecologic laparoscopy is between 1.4 and 2.0 ng/mL.

IMPLICATIONS

The effect-site concentration for propofol at awakening was virtually independent of the fentanyl effect-site concentration over the range of 0.8 to 3.0 ng/mL; however, 0.8 ng/mL of fentanyl was associated with inadequate postoperative analgesia, and 3.0 ng/mL of fentanyl was associated with respiratory toxicity. The optimal postoperative fentanyl effect-site concentration during recovery from propofol general anesthesia for laparotomy thus appears to be near 2 ng/mL.

[Rapid sequence intubation in emergency: is there any place for fentanyl?]

OBJECTIVES

Rapid sequence intubation (RSI) with the association of etomidate and succinylcholine is the French "Gold standard" for urgent "full stomach" endotracheal intubations. The aim of this study is to assess the fentanyl as a co-induction agent to take over the sedation between the RSI and the keeping of sedation, which is a critical period in which harmful neuro-vegetatives events, and awakening signs are frequently seen.

STUDY DESIGN

Randomized, double blind controlled prospective study, after acceptation by the local ethical committee.

PATIENTS AND METHODS

Three groups of patients undergoing RSI in the intensive care unit and by the out-of-hospital medical team were compared: group A patients received fentanyl 3 micrograms kg-1 during RSI, before paralysis was induced. Group B patients received the same dose of fentanyl immediately after endotracheal intubation. Group C patients did not received fentanyl (control group). Outcome measures were awakening signs arrival (respiratory movements, eyes opening, spontaneous limb movements), Ramsay score assessment, and haemody namics. Attempt at intubation and vomiting incident were also measured. Discrete data were compared by chi-2 analysis, continuous data were compared with two-way analysis of variance. A p value < 0.05 was the significant threshold.

RESULTS

Thirty-six patients were enrolled and completed the study. All the included patients presented awakening signs. The use of fentanyl did not prevent the recourse of other sedative medications. Ten minutes after endotracheal intubation, significant differences has been noticed for the awakening signs arrival between fentanyl groups (A: 42% and B: 36%) and control group (C: 77%). The Ramsay score evolution follows the same variation. All the patients were intubated on the first attempt, there was no vomiting incident noticed.

CONCLUSION

The use of fentanyl, as a co-induction agent with etomidate and succinylcholine during RSI, allows a significant delay of the awakening signs arrival and attenuate the neurovegetative response during the minutes after endotracheal intubation after RSI, without deleterious haemodynamic effects.

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.

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.

In patients with head injury undergoing rapid sequence intubation, does pretreatment with intravenous lignocaine/lidocaine lead to an improved neurological outcome? A review of the literature

It is well known that laryngeal instrumentation and endotracheal intubation is associated with a marked, transient rise in intracranial pressure (ICP). Patients with head injury requiring endotracheal intubation are considered particularly at risk from this transient rise in ICP as it reduces cerebral perfusion and thus may increase secondary brain injury. The favoured method for securing a definitive airway in this patient group is by rapid sequence intubation (RSI). In the United States the Emergency Airway Course teaches emergency physicians to routinely administer intravenous lidocaine as a pre treatment for RSI in this patient group in an attempt to attenuate this rise in ICP. A literature search was carried out to identify studies in which intravenous lidocaine was used as a pretreatment for RSI in major head injury. Any link to an improved neurological outcome was also sought. Papers identified were appraised in the manner recommended by the evidence based medicine group to ensure validity. There were no studies identified that answered our question directly and, furthermore, it is our belief that no such study, at present, exists in the literature. Six valid papers were found, which individually contained elements of the question posed and these are presented in a narrative and graphic form. There is currently no evidence to support the use of intravenous lidocaine as a pretreatment for RSI in patients with head injury and its use should only occur in clinical trials.

The efficacy of esmolol versus lidocaine to attenuate the hemodynamic response to intubation in isolated head trauma patients

OBJECTIVE

To assess the effect of esmolol vs lidocaine to attenuate the detrimental rise in heart rate and blood pressure during intubation of patients with isolated head trauma.

METHODS

This was a prospective, double-blind, randomized study, performed at an urban, county teaching emergency department. Participants were 30 patients with isolated head trauma. Each underwent a standardized intubation protocol including esmolol or lidocaine, both at 2 mg/kg.

RESULTS

Esmolol was used in 16 patients and lidocaine in 14. Mechanisms of injury included 12 assaults, 6 motor vehicle collisions, 6 falls, 4 auto-vs-pedestrian crashes, and 2 bicycle incidents. Mean ethanol level was 0.116+/-0.133 SD (range 0-0.482). Mean Glasgow Coma Scale (GCS) score was 7.9+/-4.0 SD. Cranial computed tomography (CT) hemorrhagic findings included 9 subdural/epidural hematomas, 6 cortex hemorrhages, and 2 multi-hemorrhages. Eleven patients received surgical intervention: 9 patients received a craniotomy, and 2 a ventricular catheter. The 2-minute time interval around intubation was used to assess each drug's efficacy. The mean difference change between groups for heart rate was 4.0 beats/min (95% CI = -17.7 to 9.7 beats/min), for systolic blood pressure was 1.3 mm Hg (95% CI = -27.8 to 30.4 mm Hg), and for diastolic blood pressure was 2.6 mm Hg (95% CI = -27.1 to 21.9 mm Hg). The power of this study was 90% to detect a 20-beat/min difference in heart rate, a 35-mm Hg difference in systolic blood pressure, and a 20-mm Hg difference in diastolic blood pressure.

CONCLUSIONS

Esmolol and lidocaine have similar efficacies to attenuate moderate hemodynamic response to intubation of patients with isolated head trauma.

Evaluation of the cardiovascular responses to fiberoptic orotracheal intubation with television monitoring: comparison with conventional direct laryngoscopy

STUDY OBJECTIVE

To evaluate and compare cardiovascular responses to a new method of orotracheal intubation incorporating TV monitoring, with conventional orotracheal intubation via rigid blade laryngoscopy.

DESIGN

Prospective single-blind study.

SETTING

Operating room of a medical college hospital.

PATIENTS

90 ASA physical status I and II surgical patients requiring general anesthesia and orotracheal intubation.

INTERVENTIONS

Patients were randomly allocated to two groups, one for the new intubation method and the other for conventional intubation using a rigid laryngoscope. In the new method, an anesthesiologist inserted an endotracheal tube alone into the trachea via TV monitoring through the bronchoscope, which was inserted by an assistant through the mouth to the middle larynx. The patient's trachea was intubated without extreme stretching of laryngeal tissues or deep insertion of the tip of the bronchoscope. In the conventional method, orotracheal intubation was performed with rigid direct laryngoscopy.

MEASUREMENTS

Noninvasive blood pressure (BP) and heart rate (HR) were measured before arrival at the operating room, and before and after orotracheal intubation.

MAIN RESULTS

Although this method was expected to be a minimally invasive fiberoptic intubation technique, the patients showed significant increases in BP and HR. No significant differences between the two groups were observed in cardiovascular responses immediately after intubation: the systolic BP, 169.5 +/- 28.3 versus 167.0 +/- 23.1 mmHg, and HR, 100.2 +/- 18.2 versus 98.8 +/- 16.6 bpm.

CONCLUSIONS

Insertion of an endotracheal tube may itself be the most invasive stimulus during intubation procedures.

Emergent management of the airway. New pharmacology and the control of comorbidities in cardiac disease, ischemia, and valvular heart disease

Once it is decided that the patient in distress requires tracheal intubation, the primary goal is to secure the airway as quickly and safely as possible to assure adequate oxygenation and ventilation. The clinician should quickly review the patient's history, physical examination findings, and laboratory data to determine the presence of cardiovascular disease, assess intravascular volume status, and formulate a plan for induction of anesthesia. The stresses of hypoxia, hypercarbia, acidosis, and extreme fatigue result in near-maximal sympathetic outflow that is manifest as tachycardia, labile blood pressure, and increased myocardial contractility. The astute clinician should anticipate that the tachycardia and hypertension associated with laryngoscopy and tracheal intubation is followed by a period of hypotension. This postintubation hypotension results from the acute marked attenuation of the sympathetic tone associated with resolution of hypoxia and hypercarbia, direct drug-induced negative inotropic effect, and vasodilation. The decrease in sympathetic vascular tone may result in hypotension by exacerbating the decrease in cardiac preload and afterload from hypovolemia. In addition, the use of positive pressure ventilation and positive end-expiratory pressure (PEEP) in these hypovolemic patients will further decrease ventricular preload by impeding venous return, leading to profound hypotension. Several pharmacologic agents are required to treat effectively the hemodynamic perturbations associated with induction, laryngoscopy, and tracheal intubation. Most sedative hypnotic agents that are administered for induction provide minimal to no analgesia. Patients are most often given a combination of drugs to provide adequate sedation, analgesia to blunt the noxious stimuli, and muscle relaxation to facilitate the laryngoscopy. The major challenge is to choose a combination of drugs that at the appropriate doses, effectively blunt the responses to intubation without contributing to postlaryngoscopy hypotension. One can use several strategies to accomplish these goals; administration of a narcotic analgesic before induction decreases the dose of induction agent and can attenuate the sympathetic response to intubation. Because of the prevalence of cardiovascular disease and hypovolemia in this population of patients, all chosen drugs should have minimal negative effect on cardiac function and patients with hypovolemia should be hydrated. Most clinical studies have been performed in hemodynamically stable patients, so the routine dosages of sedative hypnotics should be reduced substantially and titrated to effect. An additional strategy is to treat significant hemodynamic perturbations with vasopressors, vasodilators, short-acting selective beta-1 blockers, and inotropic agents. The choice of vasoactive agent depends on the magnitude of the hemodynamic response and the presence of specific underlying cardiovascular pathology.

Small-dose fentanyl: optimal time of injection for blunting the circulatory responses to tracheal intubation

This study was designed to examine the optimal time of injection of a small dose of fentanyl during anesthetic induction to attenuate circulatory responses to laryngoscopy and tracheal intubation. One hundred seventy patients were randomly assigned to one of five groups. In Groups II, III, IV, and V, patients received fentanyl (2 microg/kg) 1, 3, 5, or 10 min before tracheal intubation, respectively. Group I patients did not receive fentanyl and served as the control group. In Groups III and IV, blood pressures were not increased, except diastolic pressure in Group III, significantly postintubation compared with preinduction values; but Groups I, II, and V showed a significant increase (P < 0.05). The 1-min postintubation values of systolic, diastolic, and mean arterial pressure in Groups III and IV were less than those in the control group (P < 0.05). Increases of heart rate in Group IV were less (P < 0.05) than those in the control group, but significant differences were not observed in Groups II, III, and V. The number of patients with tachycardia and dysrhythmia was significantly smaller in Group IV than in the control group (P < 0.05). We conclude that the most effective time to administer fentanyl to protect circulatory responses to laryngoscopy and tracheal intubation is 5 min before tracheal intubation.

IMPLICATIONS

Fentanyl is often used to reduce the hemodynamic response to tracheal intubation. However, large doses may cause unwanted side effects. Administration of fentanyl at the optimal time reduces the dose required. Our results indicate that optimal injection time of fentanyl for intubation is 5 min before intubation.

Controlling the hemodynamic response to laryngoscopy and endotracheal intubation

The hemodynamic response to the stress of laryngoscopy and endotracheal intubation does not present a problem for most patients. However, patients with cardiovascular or cerebral disease may be at increased risk of morbidity and mortality from the tachycardia and hypertension resulting from this stress. These hemodynamic effects gained notice after the introduction and use of muscle relaxants, such as curare and succinylcholine, for endotracheal intubation at the time of anesthesia induction. A variety of anesthetic techniques and drugs are available to control the hemodynamic response to laryngoscopy and intubation. The method or drug of choice depends on many factors, including the urgency and length of surgery, choice of anesthetic technique, route of administration, medical condition of the patient, and individual preference. The possible solutions number as many as the medications and techniques available and depend on the individual patient and anesthesia care provider. This paper reviews these medications and techniques to guide the clinician in choosing the best methods.

Nebulized bupivacaine attenuates the heart rate response following tracheal intubation

STUDY OBJECTIVE

To determine whether nebulized bupivacaine attenuates the acute hemodynamic response to laryngoscopy and intubation.

DESIGN

Prospective, randomized, placebo-controlled study.

SETTING

Operating room at a university medical center.

PATIENTS

40 health ASA physical status I and II patients scheduled for minor surgical procedures.

INTERVENTIONS

Patients were randomized to receive 4 ml of a nebulized solution of either saline (n = 20) or 0.75% bupivacaine (n = 20) 15 minutes before induction of anesthesia. On completion of the aerosol treatment, fentanyl 1.5 micrograms/kg was given intravenously (i.v.), and 3 minutes later anesthesia was induced with thiopental sodium 5 mg/kg i.v. and succinylcholine 1.5 mg/kg i.v.. Laryngoscopy was begun 60 seconds after induction, and the trachea was intubated at 90 seconds. Anesthesia was maintained with 50% nitrous oxide in oxygen following intubation, and 1% isoflurane was administered at 180 seconds.

MEASUREMENTS AND MAIN RESULTS

Heart rate (HR) and blood pressure were recorded automatically every 30 seconds for 5 minutes. Bupivacaine significantly attenuated HR (p < 0.05) but not the hypertensive response to laryngoscopy and intubation.

CONCLUSION

Nebulized 0.75% bupivacaine was only partially effective in blunting the hemodynamic response to tracheal intubation.

Fentanyl attenuates cardiovascular responses to tracheal extubation

We carried out a controlled, randomized, double-blind study to examine the effects of intravenous fentanyl (1 or 2 micrograms kg-1) on hemodynamic changes during tracheal extubation and emergence from anesthesia in 60 ASA physical status I or II patients undergoing elective gynecological surgery. Anesthesia was maintained with 0.5%-1.5% isoflurane and 60% nitrous oxide (N2O) in oxygen. Muscle relaxation was achieved with vecuronium. The patients were randomly assigned to three group (each, n = 20), and fentanyl (1 or 2 micrograms kg-1), or saline (as a control) was given at the time of peritoneal closure. Changes in heart rate (HR) and blood pressure (BP) were measured during and after tracheal extubation. Adverse effects, including postoperative sedation and respiratory depression, were also assessed. The HR, systolic BP, and diastolic BP increased significantly during tracheal extubation in the control group (P < 0.05). Fentanyl 2 micrograms kg-1 attenuated the increases in these variables more effectively than fentanyl 1 microgram kg-1. The time interval from the study drug to extubation was similar in each group. Postoperative somnolence and respiratory depression were not observed in any patients in any of the three groups. We concluded that a bolus dose of intravenous fentanyl 2 micrograms kg-1 given at the time of peritoneal closure was of value in attenuating the cardiovascular changes associated with tracheal extubation and emergence from anesthesia, and that this treatment did not prolong the recovery. However, further studies are required to assess this technique in patients with cardiovascular or cerebrovascular diseases.

Prophylactic lidocaine use preintubation: a review

This article is a review of the use of prophylactic lidocaine as a preintubation medication. Intubation is associated with a cardiovascular response of elevated blood pressure and pulse, cough reflexes, occasional dysrhythmias, increased intracranial pressure, and increased intraocular pressure. In patients with atherosclerotic heart disease, potential intracranial lesions, and potential penetrating eye injuries, these responses to intubation are of greater risk. Various studies have reviewed the effect of lidocaine to blunt these responses. It is agreed that lidocaine blunts cough reflexes and dysrhythmias. Some studies note a response of lidocaine in blunting rises in pulse, blood pressure, intracranial and intraocular pressure. No studies document any harmful effects of prophylactic lidocaine given preintubation. A dose of prophylactic lidocaine of 1.5 mg/kg given intravenously 3 minutes before intubation is optimal. For suctioning of intubated patients, lidocaine can be given endotracheally in a 5-6 mg/kg dose diluted in 6 cc via simple administration at the entrance to the endotracheal tube.

Rapid-sequence intubation in head trauma

Elevated intracranial pressure commonly is associated with severe head injury. Emergency airway management technique in the patient who has sustained severe head injury must optimize conditions for intubation, minimize the adverse effects of intubation, and permit rapid and effective management of the elevated intracranial pressure. Disturbances in autoregulation make the injured brain particularly susceptible to the adverse effects of alterations of systemic blood pressure. Airway manipulation without adequate pharmacologic support can cause precipitous changes in systemic hemodynamic parameters. This article reviews the physiologic and pathologic relationship among airway management, systemic hemodynamic parameters, and intracranial pressure. Specific recommendations for the use of neuromuscular blocking agents, anesthetic induction agents, and adjunctive medications are provided.

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

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

Emergency management of the airway outside the operating room

Successful emergency airway intervention incorporates the anaesthetist's basic skills in airway management with the knowledge of the special nature of the clinical problems that arise outside the operating room. While a thorough but rapid evaluation of the key anatomical and physiological factors of an individual patient may result in an obvious choice for optimal management, clinical problems often arise in which there is not an evident "best approach." In these less clear-cut situations, the anaesthetist may do well to employ those techniques with which she/he has the greatest skills and experience. At times, however, some degree of creative improvisation is required to care for an especially difficult problem.

Haemodynamic responses to tracheal intubation following etomidate and fentanyl for anaesthetic induction

The haemodynamic response to anaesthetic induction and tracheal intubation was studied in 29 patients undergoing elective myocardial revascularization surgery. All patients included in the study were anaesthetized with etomidate, 0.3 mg.kg-1. The patients were randomized to three groups: Group I received fentanyl, 2.5 micrograms.kg-1; Group II received fentanyl, 5 micrograms.kg-1; and Group III received fentanyl, 10 micrograms.kg-1. Haemodynamic variables were measured at baseline (awake), after anaesthetic induction, and at one, three, five, and ten minutes after tracheal intubation. The number of patients with haemodynamic responses to intubation (> 20% increase in heart rate or mean arterial pressure) was greater (P < 0.05) in Group I than in Groups II and III. Statistically significant, but clinically minor, decreases in mean arterial pressure and cardiac output occurred in all groups at the last three study times. The frequency of involuntary muscle movements was 14%, and all of these events occurred in patients in Group I. In conclusion, the authors recommend using fentanyl, 5-10 micrograms.kg-1 to blunt the haemodynamic response to tracheal intubation following anaesthetic induction with etomidate, 0.3 mg.kg-1.

Cardiovascular responses to fiberoptic intubation: A comparison of orotracheal and nasotracheal intubation

We compared the cardiovascular responses between nasal and oral intubation with a fiberoptic bronchoscope under the combination of neuroleptic analgesia (NLA) and topical anesthesia. The 16 patients studied were divided into 2 groups: the nasal intubation group (N group: 8 patients) and the oral intubation group (O group: 8 patients). There were significant changes in systolic, diastolic and mean arterial pressures in the N group and in the pressure rate quotient in the O group. Diastolic arterial pressure and heart rate were significantly higher in the N group than in the O group before induction of general anesthesia. The rate pressure product (RPP) was significantly higher in the N group than in the O group at some points during the procedure. The individual RPP in both groups was relatively stable except for one patient in the N group, who had a marked increase in RPP during the procedure. We conclude that, under the combination of NLA and topical anesthesia, the cardiovascular responses to oral fiberoptic intubation are less severe than those to the nasal approach. The oral approach is recommended, especially in patients with coronary artery disease, taking into consideration of the cardiovascular responses to fiberoptic intubation.