Catecholamine response to laryngoscopy and intubation

The haemodynamic response and changes in plasma catecholamine concentrations associated with laryngoscopy and tracheal intubation were compared during anaesthesia employing three strictly standardised techniques with commonly used drug combinations. Thirty-six patients were investigated consecutively resulting in 12 patients in each of three study groups. Anaesthesia was induced with thiopentone 5 mg.kg-1 (group 1), fentanyl 6 micrograms.kg-1 with thiopentone 5 mg.kg-1 (group 2), or midazolam 0.2 mg.kg-1 with fentanyl 6 micrograms.kg-1 (group 3). Undesirable changes in haemodynamic effects and an elevation of plasma catecholamine concentrations during laryngoscopy and intubation occurred in group 1. Heart rate and mean arterial pressure increased significantly (34% and 23% respectively). Noradrenaline concentration increased by a maximum of 147%. The addition of fentanyl (groups 2 and 3) attenuated the adverse haemodynamic response and elevation of plasma catecholamine concentrations; heart rate and mean arterial pressure did not differ from pre-intubation values and plasma catecholamine concentrations decreased steadily. Substitution of thiopentone by midazolam in combination with fentanyl abolished the adverse haemodynamic response and modified the increase in plasma catecholamine concentrations. 'High-dose' opioid anaesthesia is not necessary to produce optimal conditions during laryngoscopy and intubation.     

Blood pressure and heart rate changes during intubation: a comparison of direct laryngoscopy and a fibreoptic method

Blood pressure and heart rate changes during nasotracheal intubation under general anaesthesia were studied in 100 patients who were randomly allocated to fibreoptic bronchoscope or direct laryngoscopy intubation. Noninvasive blood pressure and heart rate were recorded before and immediately after anaesthesia induction, at anaesthesia intubation and every minute thereafter for 5 min. Nasotracheal intubation was accompanied by significant increases in blood pressure and heart rate compared to baseline values in both groups. Blood pressure and heart rate at intubation, and the maximum values of blood pressure during the observation were significantly higher in the fibreoptic bronchoscope group. However, the maximum values of heart rate were not significantly different between the two groups. Fibreoptic nasotracheal intubation may result in more severe pressor and tachycardiac responses than direct laryngoscopic nasotracheal intubation.     

Does the choice of the neuromuscular blocking agent affect the cardiovascular response to intubation?

Heart rate and arterial pressure changes induced by tracheal intubation, 3 min after administration of atracurium, vecuronium, tubocurarine, pancuronium or alcuronium, have been studied under thiopentonenitrous oxide-oxygen anaesthesia supplemented by either 0.5% halothane or fentanyl 2 micrograms kg-1. Pancuronium and alcuronium were associated with the greatest increase in heart rate and tubocurarine with the greatest decrease in arterial pressure prior to intubation. Following intubation, all groups, with the exception of tubocurarine showed a similar and significant rise in heart and arterial pressure when compared with control values. The cardiovascular response to intubation, particularly the effect on heart rate, was less marked when fentanyl was given at induction and was short lived with atracurium and vecuronium. Although those patients who received tubocurarine showed no significant rise in arterial pressure following tracheal intubation, this was due to significant hypotension occurring in this group prior to intubation.     

Butorphanol compared with fentanyl in general anaesthesia for ambulatory laparoscopy

Butorphanol was compared with fentanyl as the narcotic component of general anaesthesia for ambulatory laparoscopic surgery. This double-blind, randomized study enrolled 60 healthy women who received equianalgesic doses of fentanyl 1 microgram.kg-1 (F, n = 30) or butorphanol 20 micrograms.kg-1 (B, n = 30) prior to induction of anaesthesia. Tracheal anaesthesia was maintained with nitrous oxide/oxygen, isoflurane, and succinylcholine by infusion. Intraoperatively, patients who received B demonstrated lower pulse rate before and after intubation (P less than 0.05, P less than 0.01) and lower diastolic blood pressure after intubation (P less than 0.01). Anesthesiologists judged the maintenance phase as satisfactory more often with B (P less than 0.05). Postoperatively, there were no differences in analgesic need. No major side-effects occurred in either group. Among minor side-effects, patients who received B reported postoperative sedation more often, 77% vs 37% (P less than 0.01), which occurred during the first 45 min of recovery (P less than 0.05). Discharge times were not different. On the first postoperative day, more subjects who received B were satisfied with their anaesthesia experience (P less than 0.05). Butorphanol 20 micrograms.kg-1 is an acceptable alternative analgesic in general anaesthesia for ambulatory laparoscopy.     

Effect of remifentanil on the haemodynamic response to orotracheal intubation

We have examined the effect of remifentanil on the haemodynamic response to orotracheal intubation in a randomized, double-blind study. We studied 40 patients allocated to one of four groups of 10 each, to receive the following immediately before induction of anaesthesia: remifentanil 1 microgram kg-1 bolus over 30 s, followed by an infusion of 0.5 microgram kg-1 min-1; saline placebo only; glycopyrrolate 200 micrograms and remifentanil 1 microgram kg-1 bolus over 30 s, followed by an infusion of 0.5 microgram kg-1 min-1; or glycopyrrolate 200 micrograms only. Anaesthesia was induced with propofol, vecuronium and 1% isoflurane with 66% nitrous oxide in oxygen. The trachea was intubated under direct laryngoscopy 3 min after induction of anaesthesia. Arterial pressure and heart rate were measured non- invasively, immediately before induction of anaesthesia and then at 1- min intervals. Remifentanil was found to effectively attenuate the pressor response to intubation (P < 0.05 for the increase in mean arterial pressure; P < 0.01 for the increase in heart rate). In the absence of a concurrent vagolytic agent, remifentanil was associated with bradycardia or hypotension, or both, in five of 10 patients, compared with one patient who received remifentanil and glycopyrrolate.      

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

The purpose of this randomized, double-blind study was to compare the ability of a combination of fentanyl and esmolol to blunt the haemodynamic effects of intubation with that of either agent alone. Patients received fentanyl or saline four minutes before, and esmolol or saline two minutes before rapid-sequence induction of anaesthesia. The F2 group (n = 24) received fentanyl 2 micrograms.kg-1, the E2 group (n = 24) received esmolol 2 mg.kg-1, the F2/E2 group (n = 25) received a combination of fentanyl 2 micrograms.kg-1 and esmolol 2 mg.kg-1, and the F5 group (n = 26) received fentanyl 5 micrograms.kg-1. Following tracheal intubation, the maximum percent change from baseline heart rate was less in the F2/E2 and F5 groups (12% and 16% respectively) than in the E2 group (34%)(P < 0.05). The maximum percent changes from baseline systolic blood pressure in the F2/E2 and F5 groups (15% and 6% respectively) were less than in the F2 and E2 groups (24% and 33% respectively) (P < 0.05). The combination of a low dose of fentanyl and esmolol provides an alternative to a higher dose of fentanyl for blunting the haemodynamic responses to laryngoscopy and tracheal intubation during rapid-sequence induction in healthy patients.     

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.      

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.      

Comparison of Alfentanil and Fentanyl as Supplements to Induction of Anaesthesia with Thiopentone

In 120 premedicated patients undergoing general surgery, anaesthesia was induced with thiopentone 3 mg kg-1, preceded by alfentanil 4.5, 9.0 or 13.5 micrograms kg-1 or fentanyl 1.5 micrograms kg-1. The largest alfentanil dose attenuated the arterial blood pressure response to laryngoscopy and intubation better than the smaller doses of alfentanil. Changes in frontal muscle electromyogram or plasma cortisol and prolactin levels were not dependent on the adjuvant used. After thiopentone, 30, 7 and 17% of the patients given alfentanil 9.0 and 13.5 micrograms kg-1 and fentanyl 1.5 micrograms kg-1, respectively, reacted to pinching of the lower abdomen. Patients given alfentanil 4.5 micrograms kg-1 did not tolerate the endotracheal tube after recovery from suxamethonium block and their heart rate was increased 12 min after alfentanil administration. We conclude that the antinociceptive effect of alfentanil is distinctly shorter than that of fentanyl. The analgesic potency of alfentanil is between one sixth and one ninth of that of fentanyl.     

Cardiovascular effects of fibrescope-guided nasotracheal intubation

The cardiovascular effects of fibrescope-guided nasotracheal intubation were compared to those of a control group of patients who were intubated using the Macintosh laryngoscope. The 60 patients studied received a standard anaesthetic technique which included a muscle relaxant and were allocated randomly to one of two groups immediately before tracheal intubation. Systolic and diastolic arterial pressures in the fibreoptic group were significantly lower than in the control group during the first minute after intubation. The maximum increase in diastolic pressure was significantly lower in the fibreoptic group. The heart rate in the fibreoptic group was significantly higher than in the control group during all five minutes after intubation. The maximum increase in heart rate was significantly higher in the fibreoptic group. The cardiovascular responses to fibreoptic nasotracheal intubation under general anaesthesia should not cause undue concern in fit patients, but appropriate measures should be taken to prevent excessive tachycardia in compromised patients.     

Sevoflurane requirements for tracheal intubation with and without fentanyl

We studied 80 healthy ASA 1 patients (aged 20-52 yr) to determine if fentanyl affects sevoflurane requirements for achieving 50% probability of no movement in response to laryngoscopy and tracheal intubation (MAC- TI). Patients were allocated randomly to one of four fentanyl dose groups (0, 1, 2 and 4 micrograms kg-1). Patients in each group received sevoflurane at a pre-selected end-tidal concentration according to an 'up-down' technique. After steady state sevoflurane concentration had been maintained for at least 10 min, fentanyl was administered i.v. Tracheal intubation was performed 4 min after administration of fentanyl, and patients were assessed as moving or not moving. Heart rate (HR) and mean arterial pressure (MAP) were recorded before induction of anaesthesia, just before administration of fentanyl, just before laryngoscopy for intubation, and after intubation. The MAC-TI of sevoflurane was 3.55% (95% confidence intervals 3.32-3.78%), and this was reduced markedly to 2.07%, 1.45% and 1.37% by addition of fentanyl 1, 2 and 4 micrograms kg-1, with no significant difference in the reduction between 2 and 4 micrograms kg-1, showing a ceiling effect. Fentanyl attenuated haemodynamic responses (HR and MAP) to tracheal intubation in a dose-dependent manner, even with decreasing concomitant sevoflurane concentration. Fentanyl 4 micrograms kg-1 suppressed the changes in HR and MAP more effectively than fentanyl 1 or 2 micrograms kg-1 at sevoflurane concentrations close to MAC-TI.      

Bolus administration of esmolol for controlling the haemodynamic response to tracheal intubation: the canadian multicentre trial

A multicentre trial was designed to determine the dose-response and side-effects of esmolol when administered as a single iv bolus prior to induction of anaesthesia for controlling the haemodynamic response to tracheal intubation. Five hundred and forty-eight patients from 12 university-affiliated centres across Canada were randomized prospectively to receive either placebo (PLAC) or esmolol (E) in a dose of 100 mg (E100) or 200 mg (E200). Study medication was given immediately before induction of anaesthesia with thiopentone 3-5 mg.kg-1 and succinylcholine 1.5 mg.kg-1. Low-dose narcotic (fentanyl 2-3 micrograms.kg-1 or sufentanil 0.3 micrograms.kg-1) or moderate dose narcotic (fentanyl 4-7 micrograms.kg-1) was also given at five of the participating centres, whereas patients in the remaining seven centres received no narcotic. Patients who received PLAC and no narcotic had greater HR and SBP values after tracheal intubation than patients who received either E100 or E200 (P less than 0.005). The proportion of patients whose maximum HR exceeded 110 min-1 was also greater in the PLAC group (22/180) than in either the E100 (10/187) or E200 (9/181) groups (P less than 0.05), but was not different when comparing E100 with E200. Esmolol was less effective in controlling blood pressure, but, in combination with low-dose narcotic, esmolol suppressed the SBP response to tracheal intubation. In the presence of moderate-dose narcotic, however, a decrease in SBP occurred in all three groups following induction of anaesthesia (P less than 0.003), with the largest decrease (17 +/- 4%) occurring in patients who had received E200. The overall incidence of hypotension (SBP less than 90 mmHg) was greater in the E200 group (33%) than either the E100 (25%) or PLAC (16%) groups (P less than 0.05). Other side-effects, such as bradycardia, bronchospasm or pain on injection, occurred no more frequently in either esmolol group than with placebo. It is concluded that a 100 mg bolus of esmolol is safe and effective for controlling the haemodynamic response to tracheal intubation. This dose of esmolol combined with a low dose of narcotic (fentanyl 2-3 micrograms.kg-1 or equivalent) results in effective control of both heart rate and blood pressure, while avoiding important side-effects.     

Heart rate and arterial pressure changes during fibreoptic tracheal intubation under general anaesthesia

The cardiovascular responses to fibreoptic orotracheal intubation under general anaesthesia were compared with those in a control group in whom tracheal intubation was effected with a Macintosh laryngoscope. The patients received a standard anaesthetic and were allocated randomly to either group immediately before intubation. Fibreoptic intubation took significantly longer to perform. There were significant increases in heart rate and arterial pressure in both groups compared with pre-induction values. The tachycardia in the fibreoptic group was significantly greater than that in the control group during the second minute after intubation, and the increase in systolic pressure was sustained for a longer period in the fibreoptic group. The maximum increases in systolic and diastolic pressures above pre-intubation values were significantly greater in the fibreoptic group. The cardiovascular responses associated with fibreoptic intubation under general anaesthesia appear to be more severe than those which follow intubation effected with a Macintosh laryngoscope.     

Comparison of the effects of topical lignocaine spray applied before or after induction of anaesthesia on the pressor response to direct laryngoscopy and intubation

In an attempt to attenuate the cardiovascular pressor response to laryngoscopy and intubation, 30 patients presenting for routine ophthalmic surgery were studied and were randomly allocated into two groups: group A (n = 15) received direct laryngeal/tracheal lignocaine spray immediately before intubation; and group B (n = 15) received orolaryngeal lignocaine spray before the induction of anaesthesia. In both groups, general anaesthesia was induced with thiopentone 3-5 mg kg-1, followed by atracurium 0.6 mg kg-1 to facilitate tracheal intubation. Laryngoscopy and endotracheal intubation caused a significant increase in heart rate, by 28% in group A and 23% in group B (P < 0.05 in both), and in diastolic blood pressure, by 28% in group A and 24% in group B (P < 0.05 in both). In group A, the systolic blood pressure also increased significantly (by 18%) after intubation, but there was no significant change in group B. In addition, the plasma lignocaine concentrations remained well below the toxic range in both groups. It was concluded that topical lignocaine administration as an orolaryngeal spray before the induction of anaesthesia is effective in reducing but not abolishing the pressor response to laryngoscopy and endotracheal intubation.     

A comparison of hemodynamic changes with sufentanil-O2 and fentanyl-O2 anesthesia for coronary bypass grafting

Hemodynamic changes were investigated in twenty patients undergoing coronary artery bypass grafting. Thirteen patients received sufentanil-O2 anesthesia and seven patients had fentanyl-O2 anesthesia. Systolic, diastolic, as well as mean arterial blood pressures, heart rate and rate pressure product (RPP) were measured before and after intubation, one minute after skin incision, and one minute after sternotomy. The sufentanil group received 3-5 micrograms.kg-1 of sufentanil for induction and a continuous infusion of 2.5-5.0 micrograms.kg-1.hour-1. The fentanyl group received 10 to 20 micrograms.kg-1 for induction and a continuous infusion of 12.5 micrograms.kg-1.hour-1. In sufentanil group, a decrease of systolic as well as mean arterial pressure, heart rate and RPP was observed following induction. These results showed effective blocking of the sympathetic reflex by sufentanil. In the fentanyl group, immediately after intubation, an increase in systolic pressure, mean pressure, heart rate and RPP was observed. Particularly RPP increased to more than 12000 at this moment. Diastolic pressure was not significantly changed in each group. Stable hemodynamic parameters with no ST-T change were noticed during surgical procedure in each group. We conclude that sufentanil is a superior narcotic agent than fentanyl for the patients undergoing CABG, and it effectively blocks sympathetic reflex activity.     

Effect of bolus dose of remifentanil on haemodynamic response to tracheal intubation

A randomized placebo-controlled double-blinded study was conducted in 40 ASA 1 and 2 patients to determine the dose response of remifentanil in attenuating the haemodynamic response to tracheal intubation. Patients were allocated to one of four groups: placebo, remifentanil 1 microgram.kg-1, remifentanil 2 micrograms.kg-1 and remifentanil 4 micrograms.kg-1. A propofol target-controlled infusion was started at 4 micrograms.ml-1 and incrementally titrated to loss of verbal contact. Muscle relaxation was provided by cisatracurium. The study drug was given three minutes later over 30 seconds, and 90 seconds later the patient's trachea was intubated under direct laryngoscopy. Baseline noninvasive blood pressure and heart rate recordings were made prior to starting target-controlled infusion, then at one-minute intervals after loss of verbal contact for the duration of the study. Demographic data and target-controlled infusion rate at intubation was similar for the groups. Following intubation, heart rate increased by 15% in the placebo group, 10% in 1 microgram.kg-1 group, with no changes in 2 micrograms.kg-1 and 4 micrograms.kg-1 groups. Systolic blood pressure following intubation increased by 30% in the placebo group, 10% in the 1 microgram.kg-1 group and remained unchanged in the 2 micrograms.kg-1 and 4 micrograms.kg-1 groups. Remifentanil 1 microgram.kg-1 attenuated the rise in heart rate and systolic blood pressure. Remifentanil 2 micrograms.kg-1 blocked the haemodynamic response completely: no further benefit was shown from increasing the dose to 4 micrograms.kg-1.     

Nifedipine versus fentanyl to prevent the pressor response to tracheal intubation

Thirty six patients, ASA I or II, undergoing surgery that required tracheal intubation, were allocated randomly into three groups of twelve. Before induction of anesthesia, they received either saline, nifedipine sublingual 10 mg or fentanyl 1.5 micrograms.kg-1 i.v. Heart rate, systolic blood pressure, diastolic blood pressure and mean blood pressure (MAP) were recorded automatically every minute for 5 minutes before induction of anesthesia, and for 5 minutes after intubation. Nifedipine was better than fentanyl in blocking the pressor response to intubation. The fentanyl dose was too small to abolish this response completely. The increase in HR and blood pressure were most evident in the control group, followed by fentanyl, and the least increase was seen with nifedipine.     

Effects of urapidil on the cardiovascular response to intratracheal intubation]

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

Remifentanil vs. fentanyl during interventional rigid bronchoscopy under general anaesthesia and spontaneous assisted ventilation.

The treatment of tracheo-bronchial diseases with rigid bronchoscopy requires general anaesthesia without tracheal intubation. Spontaneous assisted ventilation is a safe modality of ventilation. In this study the use of remifentanil and fentanyl is compared during rigid bronchoscopy with spontaneous assisted ventilation. Ninety high-risk patients received fentanyl or remifentanil with propofol for general anaesthesia. During the maintenance fentanyl was delivered at 6.1 +/- 4.6 micrograms kg-1 h-1 and remifentanil at 0.15 +/- 0.07 microgram kg-1 min-1. The same degree of intra-operative respiratory acidosis with similar good operating conditions resulted in both groups. Patients treated with remifentanil recovered more quickly compared with those in the fentanyl group (3.8 +/- 2 vs. 10.4 +/- 9.2 min, P < 0.001). In conclusion, the use of remifentanil during rigid bronchoscopy under general anaesthesia with spontaneous assisted ventilation is safe and assures good operating conditions. Moreover, remifentanil permits a more rapid recovery than fentanyl. The dose of remifentanil is higher than previously described for spontaneously breathing patients.     

The circulatory responses to fibreoptic intubation: a comparison of oral and nasal routes

The circulatory responses to fibreoptic intubation under general anaesthesia were studied in 60 adult female patients who were randomly assigned to receive either the oral or nasal route for insertion. Non-invasive blood pressure and heart rate were recorded before anaesthesia induction (baseline values), immediately after anaesthesia induction (post-induction values), at intubation and every minute for a further 5 min. The product of heart rate and systolic blood pressure (rate pressure product) at every time point was also calculated. The results showed that both fibreoptic orotracheal intubation and fibreoptic nasotracheal intubation resulted in significant increases in blood pressure, heart rate and rate pressure product compared to baseline and post-induction values. The times required to reach the maximum values of systolic blood pressure and heart rate were significantly longer in the fibreoptic nasotracheal intubation group than in the fibreoptic orotracheal intubation group. There were no significant differences between the two groups in blood pressure, heart rate and rate pressure product at any measuring point, or in the maximum values during observation. The time required for recovery of systolic blood pressure to the post-induction value was not significantly different between the two groups, but the time required for recovery of heart rate to post-induction value was significantly longer in the fibreoptic orotracheal intubation group than in the fibreoptic nasotracheal intubation group. It was concluded that both fibreoptic orotracheal and fibreoptic nasotracheal intubations could cause a similar magnitude of circulatory responses in general anaesthetised, female adults, but the tachycardic response to fibreoptic orotracheal intubation lasted longer than that to fibreoptic nasotracheal intubation.