Severe hypoglycemia reduces the shivering threshold in rabbits.

BACKGROUND: We previously reported that each 100 mg dL- 1 reduction in blood glucose over the range from ≈90 to > 300 mg dL- 1 decreases the shivering threshold (triggering core temperature) in rabbits by 1 °C. However, the effects of lower blood glucose concentrations has yet to be evaluated. We thus evaluated the relationship between the shivering threshold and blood glucose concentration over the mild-to-severe hypoglycemic range. METHODS: Thirty-nine rabbits were lightly anaesthetized with isoflurane and randomly assigned to one of the three groups: 1) severe hypoglycemia, insulin and dextrose infusions titrated to achieve blood glucose concentration at 45-75 mg dL- 1; 2) mild hypoglycemia, insulin and dextrose infusions titrated to achieve blood glucose concentration at 75-100 mg dL- 1; and 3) saline infusion. Cooling by colonic perfusion of water at 10 °C was continued until shivering occurred or esophageal core temperatures reached to 34 °C. RESULTS: The shivering threshold in the severe hypoglycemic rabbits was 35.7 ± 1.1 °C (mean ± SD); the thresholds in the mild hypoglycemic rabbits was 37.0 ± 0.7 °C; and the threshold in the control rabbits was 37.9 ± 1.0 °C. The shivering threshold increased linearly with blood glucose concentration: shivering threshold (°C) = 0.032 ∙ [blood glucose concentration (mg dL- 1)] + 34.1, R2 = 0.45. The shivering threshold thus decreased by approximately 1 °C for each 31 mg dL- 1 decrease in blood glucose concentration. CONCLUSIONS: There was a linear relationship between blood glucose and the shivering threshold over the range from severe hypoglycemia to normoglycemia. Blood glucose perturbations in the hypoglycemic range reduced the shivering threshold about three times as much as previously reported for the hyperglycemic range.

The Effects of Blood Glucose Concentration on the Shivering Threshold in Rabbits.

BACKGROUND: Hyperglycemia is common in critically ill and surgical patients, as are core temperature disturbances. The effect of hyperglycemia on thermoregulatory defenses remains unknown. We determined the effect of blood glucose concentration on the shivering threshold in rabbits. METHODS: Twenty-seven rabbits lightly anesthetized with isoflurane were randomly assigned to infusions of (1) saline, (2) insulin titrated to produce blood glucose concentrations 60 to 100 mg/dL, or (3) 50% dextrose titrated to produce blood glucose concentrations 200 to 300 mg/dL. Core temperature was reduced at a rate of 2 to 3°C/h by perfusing water at 10°C through a plastic tube positioned in the colon. Cooling continued until shivering was observed by an investigator blinded to treatment or until esophageal (core) temperature reached 34°C. Core temperatures at the onset of shivering defined the threshold. All analyses were conducted using SAS version 9.3 (SAS Institute Inc., Cary, NC). RESULTS: Rabbits given saline shivered at 37.2 ± 0.5°C (mean ± SD). Rabbits given insulin shivered at 36.3 ± 1.1°C. Rabbits given dextrose shivered at 38.0 ± 0.6°C. The shivering threshold increased as a function of blood glucose concentration: shivering threshold (°C) = 0.009 [blood glucose concentration (mg/dL)] + 35.6, r = 0.53. The shivering threshold thus increased approximately 1°C for each 100 mg/dL increase in blood glucose concentration. CONCLUSIONS: Hyperglycemia increases the threshold for shivering, whereas hypoglycemia lowers the threshold on rabbits.

[Anesthesia for a Patient with Acute Appendicitis and Idiopathic Cervical Internal Carotid Artery Vasospasms].

A 33 year-old female patient was admitted to the hospital with acute appendicitis. She had idiopathic cervical internal carotid artery vasospasms and had been taking aspirin. We used intracranial oxygen saturation measuring instrument (INVOS®) for anesthetic management during general anesthesia. We administered atropine and continuous small amount of dopamine, and loaded fluids when her blood pressure decreased. We refrained from using medicines which might influence cerebral blood flows. Intracranial oxygen saturation was maintained above baseline during the operation. Intracranial oxygen saturation measuring instrument was useful in achieving the maintenance of intracranial environment Administration of dopamine and atropine was useful and safe in keeping the circulation dynamics and intracranial tissue oxygen saturation in this patient.

[A case of severe hypotension caused by external cardiac compression by tumor and doctor's hand in a patient with mediastinal tumor].

There are several causes of hypotension during anesthesia. We report a case of severe hypotension caused by external cardiac compression. A 72-year-old man was scheduled for resection of mediastinal tumor under general anesthesia. He had undergone mediastinal tumor resection four times uneventfully. Anesthesia was induced and maintained with target controlled infusion of propofol and continuous infusion of remifentanil. Tracheal intubation was facilitated with rocuronium. Massive bleeding and severe hypotension developed during the operation. Blood transfusion, cryoprecipitate, fresh frozen plasma, and percutaneous cardiopulmonary support were commenced. However, hemorrhage was not the only cause of hypotension. The transesophageal echocardiography revealed external cardiac compression by tumor and doctor's hand. Transesophageal echocardiography was useful for verifying the causes of hypotension. It is necessary to evaluate the causes of hypotension during the operation, because a certain number of problems may exist.

High-frequency jet ventilation during video-assisted thoracoscopic surgery in a patient with previous contralateral pneumonectomy.

A case of high-frequency jet ventilation (HFJV) during video-assisted thoracoscopic surgery (VATS) in a patient with previous contralateral pneumonectomy is presented. A 77-year-old man with a right pneumothorax was scheduled for bullectomy by VATS. He had undergone left pneumonectomy due to lung cancer 6 years earlier. Anesthesia was induced and maintained with propofol and fentanyl. The patient was intubated with a normal, single-lumen endotracheal tube (ETT). HFJV was applied through the ETT during the VATS procedure. Although PaCO(2) gradually increased from 51.9 mmHg to 80.0 mmHg, appropriate surgical conditions were provided, PaO(2) was well preserved, and blood pressure and heart rate were stable throughout the VATS procedure.

Cardiac arrest after spinal anesthesia in a patient with neurally mediated syncope.

We present the case of cardiac arrest in a patient with neurally mediated syncope (NMS). A 66-year-old male patient was scheduled to undergo right inguinal hernioplasty. He had a history of syncope, which occurred a few times a year in childhood and once a year recently. One minute after the second spinal injection, cardiac arrest (asystole) developed. Sinus rhythm was restored by cardiac massage and intravenous administration of atropine and ephedrine. The operation was cancelled. The patient was diagnosed as NMS by a cardiologist. Four months later, right inguinal hernioplasty was performed, uneventfully, under general anesthesia. High sympathetic blockade due to spinal anesthesia and transient withdrawal of sympathetic tone and increase in vagal discharge due to NMS could be the main causes of the cardiac arrest. If the patient has any possibility of NMS, anesthesiologists should consider the possibility of cardiac arrest after spinal anesthesia.

The usefulness of an earphone-type infrared tympanic thermometer during cardiac surgery with cardiopulmonary bypass: clinical report.

We evaluated the usefulness of a novel earphone-type infrared tympanic thermometer (IRT) during cardiac surgery with cardiopulmonary bypass. Tympanic membrane temperature (T(Tym)) was monitored using the IRT inserted into the right ear canal of 12 adult patients (ASA III) who had been scheduled for elective cardiac surgery with cardiopulmonary bypass under general anesthesia. Rectum (T(Rec)) and nasopharyngeal temperatures (T(Naso)) were also monitored, and all temperatures were recorded at 5-min intervals during cardiopulmonary bypass. Operating room temperature was kept at 20°-27°C; a conductive warming/cooling system was used to control the patient's body temperature. Of 265 measurements obtained, body temperature range was 31.6°-37.6°C. No complications were related to site of insertion of the monitoring probe. Significant correlations were seen between T(Tym) and T(Naso) (r = 0.971, P < 0.001), and T(Tym) and T(Rec) (r = 0.759, P < 0.001). A Bland-Altman plot showed that average temperature of T (Tym) was 0.06°C above T(Naso) (±0.66°C, 2 SD) and 0.12°C below T(Rec) (±1.78°C, 2 SD). We conclude that an earphone-type IRT is noninvasive and hygienic and could continuously evaluate selective cerebral temperature during cardiopulmonary bypass in adults.

[Abnormality of thyroid function].

The thyroid hormones are synthesized by iodine. Thyroid dysfunction can develop in patients who have received treatment with iodine-containing contrast media or treatment with amiodarone. Thyrotoxicosis is a symptom due to high levels of thyroid hormone. The entity most threatened is the cardiovascular system. beta-adrenergic receptor blockade can control the heart rate. And a decreasing heart rate may improve heart-pumping function. We should aim to avoid surgery on any patients whose thyroid function is abnormal. The avoidance of a thyroid storm is the goal in managing hyperthyroid patients. Suppression of the sympathetic tone and maintenance of a deep level of surgical anesthesia are prudent. Thyroid storm is rare nowadays but still carries a high mortality. Precipitating factors include infection, surgery, childbirth or trauma, et al. Hypothyroid patients are sensitive to the effects of anesthetic agents and many drugs, including opioids. Mild hypothyroidism may have little perioperative significance. However, overt hypothyroidism can develop in a high percentage of patients with history of subclinical hypothyroidism. An untreated patient with hypothyroidism may present as an emergency with myxedema coma. Myxedema coma is rare but carries a high mortality. Precipitating factors include hypothermia, surgery, trauma, sedative drugs, et al.

[Pheochromocytoma].

0.1-0.2% of all cases of hypertension are caused by pheochromocytomas, or catecholamine-producing tumors derived from chromaffin tissue. The occurrence of combined symptoms of paroxysmal headache, sweating, and hypertension is probably a more sensitive and specific indicator than any one biochemical test for pheochromocytoma. Alpha-adrenergic receptor blockade with prazosin or doxazosin has been administered to restore plasma volume by counteracting the vasoconstrictive effects of high levels of catecholamines. Virtually all anesthetic drugs and techniques (including isoflurane, sevoflurane, remifentanil, fentanyl, and regional anesthesia) have been used with success. For intraoperative hypertension various drugs have been used and for hypotension noradrenaline, dopamine, dobutamine, and adrenaline have been used. 25-50% of hospital deaths in patients with pheochromocytoma occur during induction of anesthesia or during operative procedures for other causes. Adrenergic receptor blocking drugs probably reduce the complications of hypertensive crisis, the wide BP fluctuations during manipulation of the tumor (especially until venous drainage is obliterated), and the myocardial dysfunction that occurs perioperatively. A reduction in mortality associated with resection of pheochromocytoma (from 40% to 60% to the current 0% to 6%) occurred when alpha-adrenergic receptor blockade was introduced as preoperative preparatory therapy.

Cerebral pial vascular changes under propofol or sevoflurane anesthesia during global cerebral ischemia and reperfusion in rabbits.

BACKGROUND: Propofol and sevoflurane are commonly used anesthetics for neurosurgery. The aim of the study was to compare the effects of propofol with sevoflurane on cerebral pial arteriolar and venular diameters during global brain ischemia and reperfusion. METHODS: Japanese white rabbits were anesthetized with propofol (n=11), sevoflurane (n=9), or the combination of sevoflurane and intralipid (n=10). Global brain ischemia was induced by clamping the brachiocephalic, left common carotid, and left subclavian arteries for 15 minutes. Pial microcirculation was observed microscopically through closed cranial windows and measured using a digital-video analyzer. Measurements were recorded before clamping and afterward for 120 minutes. RESULTS: Plasma glucose and mean arterial blood pressure increased significantly during ischemia in the propofol-anesthetized rabbits. During ischemia, pial arteriolar and venular diameters decreased significantly in all groups. After unclamping, large and small, pial arteriolar and venular diameters increased temporarily and significant dilation was observed in both sevoflurane groups. From 10 minutes after unclamping until the end of the study, large and small arterioles returned to baseline diameters in the sevoflurane groups, but decreased significantly by 10% to 20% in the propofol rabbits. Ischemia-induced adverse effects such as pulmonary edema and acute brain swelling were observed primarily in propofol-anesthetized rabbits. CONCLUSION: Propofol and sevoflurane acted differently on pial vessels during reperfusion after ischemic insult. Pial arterioles and venules did not dilate immediately after reperfusion, and subsequently constricted throughout the reperfusion period in propofol-anesthetized rabbits. In contrast, pial arterioles and venules dilated temporarily and returned to baseline in sevoflurane-anesthetized rabbits.

The shivering threshold in rabbits with JM-1232(-), a new benzodiazepine receptor agonist.

BACKGROUND: JM-1232(-) is a novel isoindoline derivative which shows sedative and hypnotic activities through the benzodiazepine site of gamma-aminobutyric acid type A (GABAA) receptors. Typical doses of midazolam, another GABAA receptor agonist, slightly reduce the shivering threshold in humans. We thus determined the extent to which JM-1232(-) decreases the shivering threshold. METHODS: Eighteen rabbits, lightly anesthetized with isoflurane 0.2 minimum alveolar anesthetic concentration (MAC), were randomly assigned to infusions of 1) saline (control), 2) 0.01 mg x kg(-1) x min(-1) JM-1232(-), or 3) 0.1 mg x kg(-1) x min(-1) JM-1232(-). Body temperature was reduced at a rate of 2-3 degrees C/h by perfusing water at 10 degrees C though a U-shaped plastic tube positioned in the colon. Cooling continued until shivering was observed by an investigator blinded to treatment, or until core temperature reached 34 degrees C. Core temperatures were recorded from the distal esophagus, and core temperature at the onset of shivering defined the threshold. Data were analyzed by one-way analysis of variance with Student-Newman-Keuls tests. Results are presented as means +/- SD; P < 0.05 was considered statistically significant. RESULTS: The rabbits given a saline infusion shivered at 36.5 +/- 0.3 degrees C. Five of the six rabbits given JM-1232(-) at a rate of 0.01 mg x kg(-1) x min(-1) shivered at 35.7 +/- 0.8 degrees C, and one of these rabbits failed to shiver at 34.0 degrees C. None of the rabbits given JM-1232(-) at a rate of 0.1 mg x kg(-1) x min(-1) shivered before reaching the 34.0 degrees C cutoff temperature. CONCLUSION: A low dose of JM-1232(-) reduced the shivering threshold in rabbits approximately 0.8 degrees C which is similar to the effects in humans given premedication doses of midazolam. In contrast, a 10-fold larger dose reduced the threshold more than 2.5 degrees C. This is a substantial decrement and might facilitate induction of therapeutic hypothermia.

[Total intravenous anesthesia with propofol and remifentanil for a patient with myotonic dystrophy].

A 54-year-old woman, complicated with myotonic dystrophy, underwent laparoscopic cholecystectomy for cholelithiasis. The patient was given total intravenous anesthesia using propofol, remifentanil and vecuronium, combined with epidural anesthesia using ropivacaine. No complication occurred, and the patient recovered from anesthesia without delay. For the relief of postoperative pain, ropivacaine (0.2%) was given epidurally. The postoperative course was uneventful. The anesthesia with remifentanil is extremely useful for patients with myotonic dystrophy.

Intravenous famotidine does not always change core temperature during general anesthesia.

It has been reported that oral premedication with the H(2) receptor antagonist famotidine augmented intraoperative hypothermia. We again investigated whether the H(2) receptor antagonist famotidine significantly affected body temperature during open abdominal surgery under general anesthesia. We studied 20 female patients undergoing elective gynecological surgery. Participating patients were assigned randomly to one of two regimens: (1) 10 ml saline given intravenously just before induction of general anesthesia or (2) 20 mg famotidine in 10 ml saline given just before induction of general anesthesia. General anesthesia was induced by 2 mg x kg(-1) propofol and 0.1 mg x kg(-1) vecuronium. After tracheal intubation, anesthesia was maintained with sevoflurane (1%-2%) in nitrous oxide (2 l x min(-1)) and oxygen (1 l x min(-1)) along with 1-2 microg x kg(-1) fentanyl as needed. Tympanic temperature (T(Tym)) was measured as the core temperature, and arteriovenous perfusion of the fingertip was evaluated using the forearmminus-fingertip skin-surface temperature gradient (Grad(a-f)). T(Tym) gradually and significantly decreased in both groups during anesthesia, and no significant differences in these values were observed between the two groups. Grad(a-f) did not differ significantly between the two groups during anesthesia. We conclude that intravenous famotidine does not always change the core temperature during general anesthesia.

[Anesthetic management by total intravenous anesthesia with propofol, pentazocine and ketamine].

BACKGROUND: The authors evaluated the efficacy of anesthetic management by total intravenous anesthesia with propofol, pentazocine and ketamine. METHODS: Thirty-five patients for mastectomy were anesthetized by propofol, pentazocine and ketamine. Patients were divided into two groups by age; one is patients under 61 years of age and the others are patients above 61 years. Analysis was made retrospectively. Anesthesia was induced with propofol and ketamine and was maintained with propofol infusion and intermittent administration of vecuronium with 40% oxygen in air. Pentazocine was administrated as a bolus dose before incision. RESULTS: There were no differences in the patient background except age and height between the two groups. After induction of anesthesia, systolic and diastolic blood pressures decreased compared with those before induction in both groups. Systolic and diastolic blood pressures and heart rate increased after tracheal intubation, but the hemodynamics remained stable after the start of surgery. The induction and maintenance doses of propofol were not different between the two groups. Patients above 61 years had smaller dosage of pentazocine compared with those in patients under 61 years. The dosage of ketamine was not different between two groups. Awakening time in about 80% of patients was within 15 minutes and is not different between the two groups. Postoperative pain relief was good in both groups. Incidence of nausea and vomiting was 25% and was not the different between the two groups. CONCLUSIONS: Total intravenous anesthesia with propofol, pentazocine and ketamine would be useful to stabilize hemodynamic state, to obtain rapid recovery and to provide effective postoperative pain relief.

[Successful control of rapid heart rate with atrial flutter by intravenous administration of esmolol in a patient after total correction of the tetralogy of Fallot].

A 30-year-old woman with atrial flutter after surgical correction of tetralogy of Fallot, underwent gynecological procedure under general anesthesia. Because she had been noted to have atrial flutter and heart failure at 8 weeks' gestation, she was scheduled for dilatation and curettage. Chest X-ray film showed cardiomegaly and pulmonary congestive changes. ECG showed atrial flutter with 3:2 atrio-ventricular conduction rate and complete right branch block. She was anesthetized with propofol infused with target-controlled infusion system, fentanyl and 66% of nitrous oxide under close monitoring and appropriate respiratory management. The quantity of hemorrhage was about 850 ml, and hypovolemia was treated with volume infusion and the use of vasoactive drugs. Soon after emergence from anesthesia, atrial flutter with 1:1 A-V conduction (> 230 bpm) occurred suddenly. Esmolol hydrochloride, 30 mg, was administered. Despite the relatively low doses, rapid control of heart rate was possible in a few minutes and the atrial flutter returned to 2:1 conduction. Although atrial flutter had continued until the discharge, tachyarrhythmia was no longer observed and the heart resumed sinus rhythm 3 month after the operation. The present case suggests that esmolol can be used effectively and safely for controling atrial flutter with rapid ventricular response in a patient after surgical correction of tetralogy of Fallot.

[Anesthetic management of three patients with myotonic dystrophy in a family].

Case-1: A 24-year-old woman was admitted because of pressing hydramnion. She was treated by ritodrine hydrochlorides leading to rhabdomyolysis, and she was diagnosed as myotonic dystrophy. She underwent cesarean section because of urgent premature birth. The surgery was performed with spinal anesthesia using tetracaine. Case-2: A 1-year-old boy, the son of Case 1, underwent orchiopexy. He showed respiratory distress at birth and needed respiratory support for 140 days. The surgery was performed under general anesthesia combined with caudal anesthesia. Anesthesia was induced with nitrous oxide-oxygen-sevoflurane. He was intubated without muscle relaxants. Since he recovered consciousness soon after the surgery, he was extubated and returned to the ward. Case-3: A 30-year-old woman, the sister of Case 1, underwent tonsillectomy. At the age of 27 she underwent salpingectomy under general anesthesia with nitrous oxide-oxygen-halothane, after which she was diagnosed as myotonic dystrophy. She was anesthetized with propofol and fentanyl. Because severity of the myotonic dystrophy varies among the patients, the strategy for anesthesia should be planned on each patient. Generally speaking, regional anesthesia including spinal and epidural anesthesia is preferable.

[Intermittent complete left bundle branch block during general anesthesia].

We report a case of intermittent complete left bundle branch block (CLBBB) which occurred during general anesthesia. An 83-year-old female was scheduled for upper lobectomy of the right lung under general anesthesia. Her preoperative 12-lead ECG showed atrial fibrillation and ST-depression in V4-6. Anesthesia was induced with propofol and pentazocine, and maintained with 0.5-1.5% isoflurane, 0-50% nitrous oxide in oxygen under close monitoring and appropriate respiratory management. The operation was performed uneventfully. Several minutes after the end of surgery, on converting her into the supine position from the left lateral decubitus position, widened QRS complexes, later diagnosed as CLBBB, appeared on ECG. At that time, heart rate was 92 beats x min(-1). After the administration of esmolol hydrochloride, heart rate decreased rapidly in a few minutes and ECG returned to normal conduction from CLBBB. We diagnosed this as rate-dependent intermittent CLBBB. Although intermittent CLBBB continued until the next day, the patient was asymptomatic and cardiac enzymes were within normal ranges. The intermittent CLBBB, which occasionally occurs during anesthesia, makes the diagnosis of myocardial ischemia and acute myocardial infarction difficult. The present case suggests that esmolol can be used effectively and safely to distinguish CLBBB as a benign disorder from myocardial ischemia in a patient with CLBBB.

[Double-lumen tracheostomy tube (Tracheopart) used in two patients for one-lung ventilation under general anesthesia].

Double-lumen tracheostomy tube (Tracheopart, RUSCH) is now available in Japan. We used the device to perform one-lung ventilation in two patients with previous laryngectomy and permanent tracheostomy. Reliable fixation and observation of the right position during the operation are especially important throughout the procedure. We think that this device needs more improvements regarding its size and length.

[Anesthetic management in a patient complicated with left coronary artery-left ventricular fistulae].

We have experienced anesthetic management for posterior lumbar interbody fusion in a 76-year-old female with left coronary artery-left ventricular fistulae. She was admitted to our hospital because of chest pain and was found to have left coronary artery-left ventricular fistulae 6 months before this operation. The electrocardiogram at rest showed T-wave inversions in leads V3-V6. Selective coronary angiography showed the contrast medium streaming into the left ventricle via a maze of fine vessels from the distal left anterior descending coronary artery. Cardiac catheterization revealed left ventricular end-diastolic pressure of 30 mmHg and mean pulmonary capillary wedge pressure of 16 mmHg. Anesthesia was induced with intravenous propofol 60 mmHg, fentanyl 0.1 mg and vecuronium 6 mg, and maintained with 50% nitrous oxide and isoflurane (0.5-1.5%) in oxygen with meticulous intravenous administration of fentanyl. Cardiac function was evaluated with Swan-Ganz catheter during anesthesia. Dopamine and prostaglandin E1 ware continuously infused intravenously to decrease high afterload and maintain cardiac output. The operative and post-operative courses were uneventful. Coronary artery-left ventricular fistulae are extremely rare and can cause myocardial ischemia from coronary steal. A careful management with meticulous anesthetic care is emphasized for patients with coronary artery-left ventricular fistulae.

[Pretreatment with lidocaine accelerates onset of vecuronium-induced neuromuscular blockade].

The purpose of this study was to investigate the effect of pre-treatment with lidocaine on the onset of vecuronium-induced neuromuscular block in a randomized, double-blinded trial. Thirty-one patients were randomly allocated to one of two groups according to the agents administrated 3 min prior to vecuronium injection; Group C, normal saline 0.75 ml.kg-1 and Group L, 2% lidocaine 1.5 mg.kg-1. Anesthesia was induced with propofol 1.5 mg.kg-1 followed by continuous infusion at 8 mg.kg-1.hr-1. Neuromuscular blockade was evaluated with accelerometry, which measured a train-of-four (TOF) pattern of abductor policies muscle. The disappearance of the first response in TOF was regarded as onset of neuromuscular block. Changes in systolic and diastolic arterial pressure (SBP, DBP) and heart rate (HR) were measured before and after tracheal intubation. Times to onset of neuromuscular blockade induced by vecuronium in Group L and Group C were 115 +/- 20 sec and 174 +/- 45 sec, respectively. After tracheal intubation, SBP, DBP and HR in both groups increased compared with those before tracheal intubation, but the changes were not significant. Changes in SBP, DBP and HR did not differ between Group L and Group C. The mechanisms by which lidocaine reduced the time to onset of neuromuscular block caused by vecuronium could not be clarified from our study, but this may be related to pre- and post-junctional effects of lidocaine at neuromuscular junction. In conclusion, administration of lidocaine prior to tracheal intubation reduces the time to onset of neuromuscular block caused by vecuronium, but does not attenuate changes in blood pressure and heart rate caused by tracheal intubation.