Rapid Sequence Induction Of Anaesthesia Research Articles

Preoxygenation: Comparison of Maximal Breathing and Tidal Volume Techniques

ChairmanResearch Associateninosj@aol.comDirector of Research LaboratoryAttending AnesthesiologistDepartment of AnesthesiologyIllinois Masonic Medical CenterChicago, IllinoisTo the Editor:—Baraka et al. 1recently demonstrated that preoxygenation using eight deep breaths within 60 s (8 DB/60 s) at an oxygen flow of 10 L/min can produce arterial oxygen tension (Pa02) values comparable to those obtained using normal tidal volume breathing (TVB) for 3 min. In addition, they showed that this technique significantly delayed the onset of apnea-induced hemoglobin desaturation.Before this new method becomes widely accepted, several issues need to be clarified. First, we wonder what role the baseline values for Pa02played in the delayed hemoglobin desaturation after 8 DB/60 s. For this portion of their study, Baraka et al. used a separate group of subjects, group B, in whom baseline Pa02values were 407 ± 53 mmHg after 3 min of TVB and 434 ± 45 mmHg after 8 DB/60 s. Both values were higher than those of subjects in group A, in whom 3 min of TVB yielded a Pa02higher than 392 ± 72 mmHg versus 369 ± 69 mmHg after 8 DB/60 s. It cannot be ruled out that the higher Pa02values observed in in group B after 8 DB/60 s contributed to the delay in hemoglobin desaturation. If subjects from group A were subjected to apnea, the benefit of 8 DB/60 s may not have been evident, or at least may not have been as dramatic.Second, we think that reporting this technique as eight breaths in 60 s underestimates the number of breaths and the time of preoxygenation. If we understand the protocol correctly, after the eight breaths, a rapid-sequence induction of anesthesia was carried out. During this period, face-mask oxygenation was continued until apnea ensued, a period described as 15 to 30 s during which an additional 2 to 4 deep breaths occurred. Thus, it appears that Baraka et al. actually evaluated the efficacy of 10 to 12 breaths during a 75 to 90 s period rather than eight deep breaths in 60 s. The authors proposed two possible mechanisms for the delayed decrease in hemoglobin saturation during 8 DB/60 s: (1) that the extra 15 to 30 s provided more alveolar oxygenation in patients breathing deeply for 60 s than during TVB; and (2) that continued deep breathing during this extra time may have opened collapsed airways or lung tissue, with a consequent increase in oxygen store in the functional residual capacity. In his editorial, Benumof 2proposed other explanations, including a leftward shift of oxyhemoglobin dissociation curve secondary to hyperventilation-induced reductions in PaCO2. We propose that by extending the duration of deep breathing beyond 60 s (i.e., to 75–90 s) may have enhanced the potential influence of this factor. A delay in desaturation caused by a leftward shift of the oxyhemoglobin dissociation curve would not necessarily favor improved oxygen transport. Because the authors presented only values for Pa02, the role of changes in arterial carbon dioxide tension and arterial pH must remain speculative.Third, Baraka et al. state that using the technique of four deep breaths in 30 s (4DB/30 s), Pa02values increased exponentially as oxygen flow is increased from 5 to 10 to 20 L/min. Although this description may accurately describe the increase from baseline values, the mean values for Pa02at 5, 10, and 20 L/min oxygen flow all decrease within the linear, essentially flat portion of the curve. The differences appear minimal, and the authors make no statement concerning the significance of the differences among the values for Pa02at the three fresh gas flows. Recently, Nimmagadda et al. 3demonstrated that increasing fresh gas flows from 5 to 7 to 10 L/min had no significant effect on end-tidal oxygen or nitrogen during preoxygenation using 4DB/30 s or 2-min TVB techniques in healthy volunteers. Although Nimmagadda et al. 3did not test 20 L/min, this value is probably not encountered in most circumstances in the operating room. Although interesting and provocative, the study of Baraka et al. is far from conclusive. More studies are required to ascertain if the 8 DB/60 s method actually delays hemoglobin desaturation, and whether this method is more beneficial than the traditional TVB. It is clearly premature to anoint the 8 DB/60 s technique as the method of choice for preoxygenation.

The potency of succinylcholine in obese adolescents.

We constructed a single-dose response curve for succinylcholine in 30 obese adolescents during thiopental-fentanyl anesthesia administration by using 100 microg/kg, 150 microg/kg, or 250 microg/kg IV. The maximal response (percent depression of neuromuscular function) of the adductor pollicis to supramaximal train-of-four stimuli was recorded by using a Datex (Helsinki, Finland) relaxograph. Linear regression and inverse prediction were used to determine doses of succinylcholine to produce 50% (ED(50)), 90% (ED(90)), and 95% (ED(95)) depression of neuromuscular function. The ED(50), ED(90), and ED(95) were 152.8 microg/kg (95% confidence interval: 77.8-299.5), 275.4 microg/kg (95% confidence interval: 142-545.7), and 344.3 microg/kg (95% confidence interval: 175.3-675. 3), respectively. This ED(50) is similar to the dose reported for similarly aged, nonobese adolescents, 147 microg/kg. The previously reported ED(95) for succinylcholine in nonobese adolescents, 270 microg/kg, is within the 95% confidence interval generated for ED(95) in our study. The potency estimates for succinylcholine in obese (body mass index > 30 kg/m(2)) adolescents are comparable to those in similarly aged nonobese adolescents when dosing is calculated based on total body mass and not lean body mass. When a rapid sequence induction of anesthesia is considered in an obese adolescent, the dose of succinylcholine should be based on actual (not lean) body mass.

Bolus Dose Remifentanil for Control of Haemodynamic Response to Tracheal Intubation During Rapid Sequence Induction of Anaesthesia

Bolus Dose Remifentanil for Control of Haemodynamic Response to Tracheal Intubation During Rapid Sequence Induction of Anaesthesia

Comparison of Intubating Conditions After Rapacuronium (Org 9487) and Succinylcholine Following Rapid Sequence Induction in Adult Patients

We have assessed intubating conditions provided by rapacuronium (Org 9487) and succinylcholine after rapid sequence induction of anaesthesia in adult patients undergoing elective surgery. We studied 335 patients, ASA I and II, in five centres. Two hundred and thirty-four subjects with normal body weight and 101 obese subjects were allocated randomly to one of four treatment groups differing in the neuromuscular blocking drug administered (rapacuronium 1.5 mg kg-1 or succinylcholine 1 mg kg-1) and in the technique used for induction of anaesthesia (fentanyl 2-3 micrograms kg-1 with thiopental 3-6 mg kg-1 or alfentanil 20 micrograms kg-1 with propofol 1.5-2 mg kg-1). Intubation was started at 50 s by an anaesthetist blinded to the drugs used. Intubating conditions were clinically acceptable (excellent or good) in 89.4% of patients after rapacuronium and in 97.4% after succinylcholine (P = 0.004), the estimated difference being 8.1% (95% confidence interval (CI) 2.0-14.1%). Neither anaesthetic technique nor subject group had an influence on intubating conditions. After intubation, the maximum increase in heart rate averaged 23.1 (SD 25.4%) and 9.4 (26.1%) after rapacuronium and succinylcholine, respectively (P

Bolus dose remifentanil for control of haemodynamic response to tracheal intubation during rapid sequence induction of anaesthesia

Bolus dose remifentanil for control of haemodynamic response to tracheal intubation during rapid sequence induction of anaesthesia

Effect of rocuronium compared with succinylcholine on intraocular pressure during rapid sequence induction of anaesthesia

We have compared the effect of rocuronium and succinylcholine on intraocular pressure (IOP) during rapid sequence induction of anaesthesia using propofol and fentanyl, in a randomized double-blind study. We studied 30 adult patients, allocated to one of two groups. Anaesthesia was induced with fentanyl 2 micrograms kg-1 and propofol until loss of verbal response. This was followed by succinylcholine 1.5 mg kg-1 (group S; n = 15) or rocuronium 0.9 mg kg-1 (group R; n = 15). Laryngoscopy was performed 60 s later. IOP, mean arterial pressure (MAP) and heart rate (HR) were measured before induction, immediately before intubation and every minute after intubation for 5 min. A Keeler Pulsair air impulse tonometer was used to measure IOP and the mean of two readings obtained in the right eye at each measurement time was recorded. Intubating conditions were evaluated according to a simple scoring system. IOP in the succinylcholine group was significantly greater than that in the rocuronium group (mean 21.6 (SEM 1.4) mm Hg vs 13.3 (1.4) mm Hg; P < 0.001). Intubating conditions were equally good in both groups. We conclude that with rapid sequence induction of anaesthesia using propofol and fentanyl, rocuronium did not cause as great an increase in IOP as succinylcholine and may be an alternative in open eye injury cases.

Comparison of intubating conditions after rapacuronium (Org 9487) and succinylcholine following rapid sequence induction in adult patients

We have assessed intubating conditions provided by rapacuronium (Org 9487) and succinylcholine after rapid sequence induction of anaesthesia in adult patients undergoing elective surgery. We studied 335 patients, ASA I and II, in five centres. Two hundred and thirty-four subjects with normal body weight and 101 obese subjects were allocated randomly to one of four treatment groups differing in the neuromuscular blocking drug administered (rapacuronium 1.5 mg kg-1 or succinylcholine 1 mg kg-1) and in the technique used for induction of anaesthesia (fentanyl 2-3 micrograms kg-1 with thiopental 3-6 mg kg-1 or alfentanil 20 micrograms kg-1 with propofol 1.5-2 mg kg-1). Intubation was started at 50 s by an anaesthetist blinded to the drugs used. Intubating conditions were clinically acceptable (excellent or good) in 89.4% of patients after rapacuronium and in 97.4% after succinylcholine (P = 0.004), the estimated difference being 8.1% (95% confidence interval (CI) 2.0-14.1%). Neither anaesthetic technique nor subject group had an influence on intubating conditions. After intubation, the maximum increase in heart rate averaged 23.1 (SD 25.4%) and 9.4 (26.1%) after rapacuronium and succinylcholine, respectively (P < 0.001). Pulmonary side effects (bronchospasm and increased airway pressure) were observed in 10.7% (95% CI 5.8-17%) and 4.1% (95% CI 1.3-8.8%) of patients given rapacuronium and succinylcholine, respectively (P = 0.021). We conclude that after rapid sequence induction of anaesthesia in adults, clinically acceptable intubating conditions were achieved less frequently after rapacuronium 1.5 mg kg-1 than after succinylcholine.

Rapid sequence induction: a questionnaire survey of its routine conduct and continued management during a failed intubation.

Two hundred and ten obstetric anaesthetists completed a questionnaire assessing how they would perform a rapid sequence induction of anaesthesia for a Caesarean section and their continued management during a failed tracheal intubation. The survey revealed considerable variation in the timing and application of cricoid pressure, the choice and dose of drugs used and the timing of their administration. The management of a difficult intubation also varied. This variability was independent of both grade of anaesthetist and frequency of practice. There appear to be at least two distinct techniques in current practice, characterised by 'fast' or 'slow' rapid sequence induction. Rapid sequence induction is clearly not a standard technique and debate is necessary to clarify the risks and benefits of its components. In particular, the rapidity of the technique and the application of cricoid pressure may contribute to the increased incidence of difficult tracheal intubation in obstetric anaesthesia.

Bolus dose remifentanil for control of haemodynamic response to tracheal intubation during rapid sequence induction of anaesthesia

The effect of three bolus doses of remifentanil on the pressor response to laryngoscopy and tracheal intubation during rapid sequence induction of anaesthesia was assessed in a randomized, double-blind, placebo-controlled study in four groups of 20 patients each. After preoxygenation, anaesthesia was induced with thiopental 5-7 mg kg-1 followed immediately by saline (placebo) or remifentanil 0.5, 1.0 or 1.25 micrograms kg-1 given as a bolus over 30 s. Cricoid pressure was applied just after loss of consciousness. Succinylcholine 1 mg kg-1 was given for neuromuscular block. Laryngoscopy and tracheal intubation were performed 1 min later. Arterial pressure and heart rate were recorded at intervals until 5 min after intubation. Remifentanil 0.5 microgram kg-1 was ineffective in controlling the increase in heart rate and arterial pressure after intubation but the 1.0 and 1.25 micrograms kg-1 doses were effective in controlling the response. The use of the 1.25 micrograms kg-1 dose was however, associated with a decrease in systolic arterial pressure to less than 90 mm Hg in seven of 20 patients.

Rapid-Sequence Induction: Practices Vary

Rapid-sequence induction of anesthesia (RSIA) is believed to minimize risk of aspiration in unfasted patients and is widely used in obstetric anesthesia for emergency cesarean section. These authors in the U.K. surveyed 210 obstetrical anesthetists about RSIA practices. All respondents practiced pre-oxygenation, but only 76% administered 100% oxygen for …

Anesthetic Implications of Laryngeal Trauma

Anesthetic Implications of Laryngeal Trauma

Massive Intraoperative Pulmonary Embolism Coincident with the Administration of Succinylcholine

Massive Intraoperative Pulmonary Embolism Coincident with the Administration of Succinylcholine

Comparison of suxamethonium and different combinations of rocuronium and mivacurium for rapid tracheal intubation in children

The use of suxamethonium in children is associated with undesirable side effects. The synergistic effect of a rocuronium-mivacurium combination can be considered as an acceptable alternative to suxamethonium in clinical practice. The calculated ED50 of the rocuronium-mivacurium mixture was only 62% of the predicted value assuming a purely additive interaction. The use of this combination has not been evaluated in children. In this two-part study, we assessed the intubating conditions and pharmacodynamics of suxamethonium, rocuronium, mivacurium or a rocuronium-mivacurium combinations in children. We studied 120 ASA I children of both sexes, aged 3-10 yr. Children were premedicated with trimeprazine 2 mg kg-1 orally, and received fentanyl 2 micrograms kg-1 and propofol 2 mg kg-1 for induction of anaesthesia. They were allocated randomly to receive one of the following drugs or drug combinations: suxamethonium 1.0 mg kg-1, mivacurium 0.2 mg kg-1, rocuronium 0.6 or 0.9 mg kg-1, mivacurium 0.1 mg kg-1 with rocuronium 0.3 mg kg-1 or mivacurium 0.15 mg kg-1 with rocuronium 0.45 mg kg-1. In part 1, 60 s after administration of the neuromuscular blocking drug or drug combination, tracheal intubation was performed in 60 children by mimicking rapid sequence induction, and intubating conditions were evaluated by a blinded investigator according to a standard score. In part 2, neuromuscular monitoring was established before administration of neuromuscular blocking agent(s) and the time from injection of drug or drug combination until complete ablation of T1 (onset) and recovery of T1 to 25% (duration) were recorded in another 60 children. The frequency of distribution of excellent or good intubating conditions in the higher dose of rocuronium and the combination groups were similar to those in the suxamethonium group, but significantly different (P < 0.05) from those in the mivacurium group. Mean onset time was faster in the suxamethonium (55.1 (SD 11.4) s), rocuronium 0.9 mg kg-1 (70.5 (37.7) s), mivacurium 0.1 mg kg-1 with rocuronium 0.3 mg kg-1 (67 (35.9) s) and mivacurium 0.15 mg kg-1 with rocuronium 0.45 mg kg-1 (55 (26.7) s) groups compared with the mivacurium 0.2 mg kg-1 (116 (26.8) s) and rocuronium 0.6 mg kg-1 (97.9 (29) s) groups. This study demonstrated that the combination of rocuronium 0.45 mg kg-1 and mivacurium 0.15 mg kg-1 could possibly be considered as an acceptable alternative to suxamethonium when rapid sequence induction of anaesthesia is indicated in children because it provides uniform excellent intubating conditions and complete neuromuscular block in < 60 s.

Comparison of suxamethonium and different combinations of rocuronium and mivacurium for rapid sequence induction of anaesthesia in children

Comparison of suxamethonium and different combinations of rocuronium and mivacurium for rapid sequence induction of anaesthesia in children

Prehospital emergency rapid sequence induction of anaesthesia.

OBJECTIVE: To determine the number of and reasons for rapid sequence inductions done by accident and emergency (A&E) doctors out of hospital as part of the activities of the MEDIC...

Attenuation of ocular and systemic responses to tracheal intubation by intravenous lignocaine

This study was undertaken to determine whether intravenous lignocaine could mitigate or prevent the ocular reactions and especially the acute increase in intraocular pressure associated with laryngoscopy and tracheal intubation. Two groups of children undergoing minor eye surgery under nitrous oxide-oxygen-halothane anaesthesia were examined. The experimental group (n = 17) received 2 mg/kg lignocaine and the controls (n = 18) an equivalent volume of saline. The incidence of local laryngeal and ocular reflexes was much lower in the lignocaine group. Pulse acceleration was significantly lower in the lignocaine group (p less than 0.025), and the maximal mean intraocular pressure was significantly less than in the control group (p less than 0.005). Other ocular reactions were recorded, and all were attenuated after lignocaine administration. The beneficial effects of lignocaine, a suppressant of autonomic reflexes, suggest that intraocular pressure, like the heart rate, rises after intubation as a result of autonomic stimulation. The use of intravenous lignocaine is thus recommended for children at risk, such as those needing an urgent operation because of lacerated eye injury under rapid sequence induction of anaesthesia.

Comparison of Nicardipine, Diltiazem, and Verapamil for Controlling the Cardiovascular Responses to Tracheal Intubation

We have compared the efficacy of three calcium channel blockers, nicardipine, diltiazem and verapamil, in attenuating the cardiovascular responses to laryngoscopy and intubation in 60 normotensive patients (ASA I) undergoing rapid sequence induction of anaesthesia with thiopentone and fentanyl. We also examined whether or not these blockers inhibited catecholamine release induced by intubation. The patients were allocated to one of four groups (n = 15 for each): saline (control), nicardipine 30 micrograms kg-1, diltiazem 0.2 mg kg-1 or verapamil 0.1 mg kg-1. Verapamil and the three other drugs were administered 45 s and 60 s before the start of direct laryngoscopy, respectively, in a double-dummy design. Anaesthesia was induced with thiopentone 4 mg kg-1 i.v. and fentanyl 2 micrograms kg-1 i.v. Tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% isoflurane and 50% nitrous oxide in oxygen. Laryngoscopy lasting 30 s was attempted 2 min after administration of thiopentone and vecuronium. Patients receiving saline exhibited significant increases in systolic and diastolic arterial pressures (AP), heart rate (HR) and plasma concentrations of catecholamines associated with tracheal intubation. The increase in AP was attenuated in patients treated with any calcium channel blocker. The greatest effect was elicited by verapamil, which attenuated the increase in HR, although nicardipine seemed to enhance tachycardia. All three drugs failed to suppress the increase in plasma catecholamine concentrations in response to tracheal intubation. These findings suggest that bolus injection of verapamil 0.1 mg kg-1 was a more effective method of controlling hypertension and tachycardia associated with intubation than diltiazem 0.2 mg kg-1 or nicardipine 30 micrograms kg-1, and that these prophylactic effects were not caused by inhibition of the catecholamine response.

Study of the safe threshold of apneic period in children during anesthesia induction

Study Objectives: (1) To investigate changes in arterial oxygen saturation via pulse oximeter (SpO 2) during apnea and after reinstitution of manual ventilation at SpO 2 of 95% or 90% following rapid sequence induction of anesthesia in children after 2-minute preoxygenation; (2) to determine whether the setting of a safe threshold of apneic period to an SpO 2 of 95% is appropriate in children during anesthetic induction; and (3) to evaluate the influences of age, body weight, and height on the time from the start of apnea to SpO 2 of 95%. Design: A clinical study of random design and comparison among groups. Setting: Operating room of a plastic surgery hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. Patients: 152 infants and children, ASA physical status I, aged 3 months to 12 years, scheduled for elective plastic surgery. Interventions: Patients were divided into three age groups: Group 1-infants 3 months to 1 year (n = 39); Group 2-children 1 to 3 years (n = 41); and Group 3-children 3 to 12 years (n = 72). Patients in each age group were randomly allocated again to Subgroups A and B. After a 2-minute preoxygenation, anesthesia was induced with thiopental 5 mg/kg, fentanyl 5 μg/kg, and suxamethonium 1.5 mg/kg. Patients were manually ventilated when SpO 2 decreased to 90% in Subgroups A and 95% in Subgroups B, respectively, during apnea. Measurements and Main Results: SpO 2 was measured continuously with a Datex pulse oximeter applied to the right index finger. During apnea, the times for SpO 2 to decrease to 99% (T 99) and 95% (T 95) in all children, and 90% (T 90) in Subgroups A were recorded. The time for SpO 2 to decrease from 95% to 90% (T 95 − 90) in Subgroups A was also measured. After reinstitution of manual ventilation, the time when SpO 2 continued to decrease (T 1) and the time from the end of apnea to recovery of SpO 2 baseline (T 2) were determined. In addition, the lowest value of SpO 2 after apnea was also recorded. The results showed that younger children were more susceptible than older children to the risk of hypoxemia during apnea. There were significant differences in T 99, T 95, T 90, and T 95 − 90 between the three age groups. T 1 and T 2 were significantly longer in Group 3 than in Groups 1 and 2. There were significant differences in the lowest values of SpO 2 following apnea among the three Subgroups A and between Subgroups A and B of each age group. During apnea, heart rate decreased gradually as SpO 2 decreased, showing a significant decrease at SpO 2 of 95%. Bradycardia was found in three children in Subgroups A. The apnea time to SpO 2 of 95% correlated well with age, weight, and height by linear regression analysis. Conclusions: The safe threshold of an apneic period setting to an SpO 2 of 95% was appropriate in children during anesthesia induction. Despite the same duration of preoxygenation, younger children were more susceptible than older ones to the risk of hypoxemia during apnea. The apnea time to Sp0 2 of 95% correlated with age, body weight, and height using linear regression analysis.

Propofol and Alfentanil Prevent the Increase in Intraocular Pressure Caused by Succinylcholine and Endotracheal Intubation During a Rapid Sequence Induction of Anesthesia

The increase in intraocular pressure (IOP) associated with succinylcholine (Sch) has made its use in patients with open globe injuries controversial.Studies that have examined techniques to prevent the increase in IOP due to Sch have shown a larger increase in IOP from the stimulus of laryngoscopy and endotracheal intubation. The purpose of our study was to examine whether the combination of propofol and alfentanil would prevent the increase in IOP due to Sch as well as endotracheal intubation during a rapid sequence induction of anesthesia. Sixty patients were randomized to receive either thiopental 5 mg/kg and Sch 1.5 mg/kg (Group I), propofol 2 mg/kg and Sch 1.5 mg/kg (Group II), or propofol 2 mg/kg, alfentanil 40 micro gram/kg, and Sch 1.5 mg/kg (Group III). The IOP was measured continuously from baseline awake (control) values until 15 s after successful intubation. All three groups had a significant decrease in IOP with the induction of anesthesia. Succinylcholine produced a consistant increase in IOP from the postinduction low in Groups I and II, but this increase was not significantly higher than baseline. The postintubation IOPs in Groups I and II were significantly higher than baseline (P < 0.001). During the entire study period, the IOP in Group III never increased above baseline. The IOP in Groups I and II had already begun to decline by 15 s postintubation, suggesting that laryngoscopy and intubation have the greatest effect on increasing IOP. We conclude that the combination of propofol and alfentanil prevents the increase in IOP from Sch as well as the increase associated with endotracheal intubation during a rapid sequence induction of anesthesia. (Anesth Analg 1996;83:814-7)

Comparison of nicardipine, diltiazem and verapamil for controlling the cardiovascular responses to tracheal intubation

We have compared the efficacy of three calcium channel blockers, nicardipine, diltiazem and verapamil, in attenuating the cardiovascular responses to laryngoscopy and intubation in 60 normotensive patients (ASA I) undergoing rapid sequence induction of anaesthesia with thiopentone and fentanyl. We also examined whether or not these blockers inhibited catecholamine release induced by intubation. The patients were allocated to one of four groups (n = 15 for each): saline (control), nicardipine 30 micrograms kg-1, diltiazem 0.2 mg kg-1 or verapamil 0.1 mg kg-1. Verapamil and the three other drugs were administered 45 s and 60 s before the start of direct laryngoscopy, respectively, in a double-dummy design. Anaesthesia was induced with thiopentone 4 mg kg-1 i.v. and fentanyl 2 micrograms kg-1 i.v. Tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% isoflurane and 50% nitrous oxide in oxygen. Laryngoscopy lasting 30 s was attempted 2 min after administration of thiopentone and vecuronium. Patients receiving saline exhibited significant increases in systolic and diastolic arterial pressures (AP), heart rate (HR) and plasma concentrations of catecholamines associated with tracheal intubation. The increase in AP was attenuated in patients treated with any calcium channel blocker. The greatest effect was elicited by verapamil, which attenuated the increase in HR, although nicardipine seemed to enhance tachycardia. All three drugs failed to suppress the increase in plasma catecholamine concentrations in response to tracheal intubation. These findings suggest that bolus injection of verapamil 0.1 mg kg-1 was a more effective method of controlling hypertension and tachycardia associated with intubation than diltiazem 0.2 mg kg-1 or nicardipine 30 micrograms kg-1, and that these prophylactic effects were not caused by inhibition of the catecholamine response.