Total intravenous anaesthesia in ponies using detomidine, ketamine and guaiphenesin: Pharmacokinetics, cardiopulmonary and endocrine effects

Pharmacokinetics and some pharmacological effects of anaesthesia induced by a combination of detomidine, ketamine and guaiphenesin were investigated in eight ponies. Cardiopulmonary function was studied and plasma met-enkephalin, dynorphin, β-endorphin; arginine vasopressin, adrenocorticotrophin, cortisol, 11-deoxycortisol and catecholamine concentrations were measured. The combination produced slight cardiorespiratory depression, hyperglycaemia and a reduction in haematocrit. There were no changes in plasma opioids, pituitary peptides or catecholamines. Plasma cortisol concentration decreased and plasma 11-deoxycortisol increased indicating a suppression of steroidogenesis. Steady state ketamine and guaiphenesin concentrations were attained during the infusion period, and ketamine concentrations likely to provide adequate analgesia for surgical operations were achieved (more than 2.2 μg ml-1). Steady state detomidine concentration was not attained. The ponies took on average 68 minutes to recover to standing and the recovery was uneventful.

EFEIFOS DO SULFATE DE MAGNESIO NA HEMODINAMICA CARDIOVASCULAR DE CAES ANESTESIADOS COM PENTOBARBITAL SODICO

Background and Objectives - A controversy exists in the literature regarding the effects of the acute administration of magnesium on the cardiovascular system of animals and humans. The purpose of this study was to evaluate the effects of hypermagnesemia on the cardiovascular hemodynamics of dogs. Methods - Sixteen mongrel dogs were anesthetized with pentobarbitone 30 mg.kg-1 and submitted to volume expansion with Ringer's solution (0.4 ml.kg-1.min-1 and mechanical ventilation with room air. In this model, the hemodynamic repercussions of the following drugs and doses were studied. pentobarbitone 5 mg.kg-1 Group 1, control - and the association of pentobarbitone and magnesium sulphate (MS), at the dose of 140 mg.kg-1 injected in 15 minutes, followed by an infusion of 80 mg.kg-1.h-1 - Group 2. The parameters studied were: heart rate, blood pressure, inferior vena cava pressure, cardiac index, systolic index and peripheral resistance index, evaluated at 5 different moments: 15(M1), 30(M2), 60(M3) and 75(M4) minutes after the first suppplementary dose of pentobarbitone and 15 minutes (M5) after the second supplementary dose. In Group 2, the moments M3, M4, M5 corresponded to 15, 30 and 60 minutes after the priming dose of magnesium sulphate. Results - Group 1 animals exhibited tachycardia since the beginning of the experiment. There was a decrease in the cardiac index, in the systolic index and an increase in the inferior vena cava pressure. Group 2 animals also exhibited tachycardia, but heart rate decreased after MS infusion. The blood pressure and the peripheral resistance index decreased. The systolic index increased and the cardiac index decreased only at the end of the experiment. Conclusions: The antiadrenergic effects of MS could have been responsible for the decrease in heart rate. The vasodilating effects of the magnesium induced the decrease in the peripheral resistance index. The systolic index increased, showing that myocardial depression did not occur.

EFEITOS DO SULFATE DE MAGNESIO NA HEMODINAMICA E FUNCAO RENAL DE CAES ANESTESIADOS CORN PENTOBARBITAL SODICO

Background and objectives - The use of magnesium sulphate for the prevention of seizures in pre-eclampsia may induce hypermagnesemia. Clinical and experimental studies are not in agreement about the effects of magnesium on the renal hemodynamics and function. We therefore studied the effects of hypermagnesemia on the renal hemodynamics and function of dogs anesthetized with pentobarbitone. Methods - Sixteen mongrel dogs were anesthetized with pentobarbitone 30 mg.kg-1 and submitted to extracellular ) and mechanical ventilation with room air. The dogs were volume expansion with Ringer's solution (0.4 ml.kg.min allocated into two groups of 8 animals, for the study of renal hemodynamics and function following the administration of 5 mg.kg-1 of pentobarbitone (Group 1 - control or of pentobarbitone associated with magnesium sulphate in the dose (Group 2). The parameters studied were: PAH of 140 mg.kg, administered in 15 minutes, followed by 80 mg.kg-1.h-1 clearance, creatinine clearance, osmolar clearance, free water clearance, renal blood flow, renal vascular resistance, filtration fraction, urinary volume, plasmatic and urinary osmolarity, urinary and fractionary excretion of sodium and potassium, measured at five moments: 15 (M1), 30 (M2), 60 (M3) and 75 (M4) minutes after the first supplementary dose of pentobarbitone and 15 minutes (M5) after the second supplementary dose in Group 1. In Group 2, the moments M3, M4, M5 were 15, 30 and 60 minutes after the priming dose of magnesium sulphate and during the maintenance dose. Results - In Group I no significant changes were observed in renal hemodynamic parameters and creatinine clearance. The extracellular volume expansion increased urinary volume and decreased urinary osmolarity as a consequence of sodium, potassium and free water clearance. The fractionary excretion of sodium was maintained. The plasmatic osmolarity increased. In Group 2, renal hemodynamic parameters and creatinine clearance were also maintained. There was an increase in renal sodium clearance, as detected by the increase in the fractionary excretion of sodium. Conclusions - Magnesium sulphate did not produce significant changes in renal hemodynamics and facilitated the renal excretion of sodium in dogs anesthetized with pentobarbitone.

Cardiorespiratory, endocrine and metabolic changes in ponies undergoing intravenous or inhalation anaesthesia

Six Welsh gelding ponies (weight 246 ± 6 kg) were premedicated with 0.03 mg/kg of acepromazine intravenously (i.v.) followed by 0.02 mg/kg of detomidine i.v. Anaesthesia was induced with 2 mg/kg of ketamine i.v. Ponies were intubated and lay in left lateral recumbency. On one occasion anaesthesia was maintained for 2 h using 1.2% halothane in oxygen. The same group of ponies were anaesthetized 1 month later using the same induction regime and anaesthesia was maintained with a combination of detomidine, ketamine and guaiphenesin, while the ponies breathed oxygen-enriched air. Electrocardiogram, heart rate, mean arterial blood pressure, cardiac output, respiratory rate, blood gases, temperature, haematocrit, glucose, lactate and cortisol were measured and cardiac index and systemic vascular resistance were calculated in both groups. Beta-endorphin, met-enkephalin, dynorphin, arginine vasopressin (AVP), adrenocorticotrophic hormone (ACTH) and catecholamines were measured in the halothane anaesthesia group only and 11-deoxycortisol during total intravenous anaesthesia (TIVA) only. Cardiorespiratory depression was more marked during halothane anaesthesia. Hyperglycaemia developed in both groups. Lactate and AVP increased during halothane anaesthesia. Cortisol increased during halothane and decreased during TIVA. There were no changes in the other hormones during anaesthesia. Recovery was smooth in both groups. TIVA produced better cardiorespiratory performance and suppressed the endocrine stress response observed during halothane anaesthesia.

Nausea e vomito em laparoscopia ginecologica: Efeitos do oxido nitroso e da metoclopramida

Background and Objectives - Gynecological laparoscopy causes high postoperative morbidity, mainly due to occurrences such as nausea and vomiting. They result from a great multiplicity of etiologies and drugs used in anesthesia may function as contributing factors. Both the emetic properties of nitrous oxide and the efficacy of metoclopramide as antiemetic agent are controversial. This study was undertaken to determine the effects of both drugs, when used alone or in combination. Methods - Eighty three physical status ASA I and II women were studied. They were premedicated with midazolam before induction of anesthesia with alfentanil and propofol. Anesthesia was maintained with isoflurane with or without nitrous oxide in oxygen. Muscle relaxation was achieved with atracurium. There were 4 groups of patients: GI: midazolam, alfentanil, propofol, atracurium, isoflurane/oxygen; GII: midazolam, alfentanil, propofol, atracurium, isoflurane/nitrous oxide/oxygen; GIII: metoclopramide, midazolam, alfentanil, propofol, atracurium, isoflurane/oxygen; GIV: metoclopramide, midazolam, alfentanil, propofol, atracurium, isoflurane/nitrous oxide/oxygen. The incidence of nausea and vomiting was assessed both in the recovery room (RR) and in the ward. Results - There were no significant differences as regards age, weight and height of the patients and duration of anesthesia and surgery. Nausea and vomiting were more frequent in patients who received N2O (GII, 50%; GIV, 33%), as compared to those who didn't receive this agent (GI and GII, 9.5% and 14.35%, respectively). Metoclopramide decreased the incidence of nausea and vomiting in the recovery room, in patients who didn't receive N2O (GII). These patients remained in the recovery room for 90 minutes. Conclusions - N2O increases the incidence of nausea and vomiting and metoclopramide is effective in reducing these complications only in the recovery room.

Peridural com ropivacaina a 1%: Experiencia com volume proporcional a estatura

Background and Objectives - Ropivacaine - a local amino amide anesthetic agent - is a plain S enantiomer which makes it a potent and low toxicity drug. The aim of our study was to evaluate 1% ropivacaine for epidural block in lower doses than those described in the literature. Methods - Thirty-eight patients, physical status ASA I and II, aged 15 to 70 years, weighing 50 to 100 kg were selected. Premedication consisted of 15 mg oral midazolam given 60 min before anesthesia induction. In the OR, after standard monitoring a catheter was inserted intravenously to administer 10 ml.kg-1 Ringers lactate solution. Epidural puncture was performed with the patient in the sitting position and 1% ropivacaine was administered in a volume corresponding to 10% of patient's height in centimeters. With the patient in the supine position, motor blockade intensity, temperature sensitivity and sensory block extension at 1, 3, 5, 7, 10, 15, 20, 30 minutes after drug injection were evaluated. Blood pressure, heart rate and adverse side effects during the course of anesthesia and in the post-anesthetic period were also observed. In the recovery room patients were followed-up until motor blockade intensity temperature sensitivity and sensory block had returned to level L2. Results - Mean values were 41.4 years of age, 68.8 kg of body weight and 165 cm height. Upper thermal blockade level was T4 and upper sensory block level was T6. Most patients showed motor block level 1 (Bromage scale) after 30 minutes of observation. Motor block mean duration was 254 minutes and temperature sensitivity 426 minutes. Only three patients had complications: two cases of hypotension and one of bradycardia. Conclusions - In the volumes used in this study, ropivacaine produced adequate analgesia and a less intense lower limb motor block which, however, was sufficient to allow for surgical procedures with low incidence of side-effects.

REDUCAO DA CONCENTRACAO ALVEOLAR MINIMA DO ISOFLURANO E DO SEVOFLURANO PELO SUFENTANIL

Background and Objectives - Inhalational anesthetics have a mild analgesic effect. The reduction of alveolar concentration (MAC) of potent volatile anesthesics by increasing plasma concentrations of opioids is desired in inhalational anesthesia. The purpose of this study was to determine the role of sufentanil in reducing sevoflurane and isoflurane MAC. Methods - Thirty eight adult patients of both genders, physical status ASA I or II, submitted to major abdominal procedures were randomly allocated into two groups. Group I (n = 24) received inahalational anesthesia with sevoflurane and Group II (n = 14) received inhalational anesthesia with isoflurane, both diluted in a mixture of N2O (1 liter) and O2 (0.5 liter). A semi-closed system with CO2 absorber and partial reinhalation was used. Ventilation was mechanically controlled. Sufentanil infusion was administered aiming at obtaining 0.5 ng.ml-1 of plasma concentration. Sufentanil plasma concentration was previously calculated by a computer software. End-tidal concentrations were obtained through a gas analyzer and measured at 15 minutes (M1), 30 minutes (M2), 60 minutes (M3), 90 minutes (M4) and 120 minutes (M5). Systolic and diastolic blood pressure (SBP and DBP) and heart rate (RR) were measured during the same periods with the addition of M0 (pre-anesthetic period). Hourly consumption of the inhalational anesthetic agent (IAC), extubation time (ET = time between admission to the recovery room and extubation) and stay in the post anesthesia recovery room (PA-RR) were also measured. Results - Type and duration of surgeries were similar for both groups. There were no statistically significant differences in MAC, SBP, DBP, RR, IAC, TE and PA-RR between groups. Systolic blood pressure in group I (sevoflurane) showed differences among periods F = 3.82 p < O.05; (M2 = M3)(M4 = M5) and M1 had a intermediate value. MAC in group I showed differences among periods F = 9.0 p < 0.05; M1 < M3. MAC in group II also showed differences among periods F = 13.03 p < O.05; M1 < (M2,M3,M4,M5). Conclusions - Both groups had similar behavior when associated to sufentanil in major abdominal surgeries. Group II showed a higher cardiac and circulatory stability.

Associacao de opioides lipofilicos a bupivacaina na anestesia peridural. Ha vantagem no aumento da dose do opioide?

Background and Objectives: - The effects of associating lipophilic opioids to local anesthetics in epidural anesthesia are not well defined. There are still questions and controversies about opioid doses to be used and their major effects in the epidural block. This study aimed at evaluating the epidural block effects in humans of the association of different fentanyl and sufentanil doses to bupivacaine with 1:200.000 epinephrine. Methods: - A double-blind randomized study was performed in 94 patients of both genders, physical status ASA I, aged between 18 and 60 years, submitted to lower abdomen, perineal or lower limb surgery. Patients without preanesthetic medication were epidurally injected with 100 mg (20 ml) 0.5% bupivacaine, 0.1 mg (0.1 ml) 1%o epinephrine plus a combination of the following drugs: BUPI Group (15 patients): 2 ml of 0.9% saline solution (SS); FENT50 Group (19 patients): 50 μg (1 ml) fentanyl + 1 ml SS; FENT100 Group (20 patients): 100 μg (2 ml) fentanyl; SUF30 Group (20 patients): 30 μg (0.6 ml) sufentanil + SS (1.4 ml); SUF100 Group (20 patients): 50 μg (1 ml) sufentanil + SS (1 ml). The following parameters were studied: onset of sensory block, analgesic block (onset time) in T12, T10 and T8, analgesic block duration in T10 and T12, motor block degree, consciousness degree, need for supplemental perioperative sedation and analgesia, hypotension, bradycardia and peri and post operative side-effects, analgesia duration, proportion of patients needing supplemental analgesia and evaluation of postoperative pain (pain analog visual scale). Results: Groups were demographically uniform. The addition of fentanyl or sufentanil did not alter major characteristics of perioperative epidural block and has not significantly increased postoperative analgesia duration as compared to the use of bupivacaine only. However, the addition of lipophilic opioids has increased the quality of perioperative anesthetic block, translated into a lesser need for supplemental analgesia (p < 0.02). The increased dose of fentanyl and especially of sufentanil has increased the incidence of perioperative drowsiness (p < 0.001) without significant increase in other side effects. Conclusions: In the conditions and doses used, the addition of lipophilic opioids to bupivacaine and the increased dose of lipophilic opioids have improved anesthetic block quality without changes in the epidural block characteristics or a significant increase in side effects, with the exception of drowsiness mainly caused by sufentanil. However, they were not able to provide a significant increase in postoperative analgesia duration.

Efeitos de diferentes doses de tenoxicam sobre a medula espinhal e as meninges. Estudo experimental em caes

Background and Objectives. The analgesic actions of nonsteroidal anti-inflammatory drugs (NSAID) result from the inhibition of the peripheral synthesis of prostaglandins. In spite of the emphasis on the peripheral action, several studies have shown the potential central action of such drugs. In rats, NSAID doses insufficient to block pain when systemically administered were effective when intrathecally injected. This effect could be mediated by interaction with descending serotoninergic ways together with neurotransmission modulation of glycine or N-methyl-D-aspartate receptors. Our goal was to study the effect of different tenoxican doses in the histology of dogs spinal cord and meninges. Methods. Thirty two dogs (7 to 17 kg) were randomly distributed in four groups: G1 - Control with distilled water (DW); G2 - 2 mg tenoxican diluted in DW; G3 - 4 mg tenoxican diluted in DW; G4 - 10 mg tenoxican diluted in DW in a constant volume of 1 ml. Anesthesia was induced with etomidate and fentanyl and dural puncture was performed with a 25G spinal needle in interspace L6-7. Animals were observed for 72 hours and subsequently euthanized by electrocution. Lumbar and sacral spinal cord segments were removed for further histologic examination. Results. All animals were clinically normal during the observation period and there has been no histologic alteration of the nervous system and meninges. Conclusions. In our experimental model intrathecal tenoxican doses up to 10 mg have not triggered nervous tissue or meningeal injuries in dogs.

Comparacao da recuperacao de anestesia venosa com propofol e anestesia inalatoria com sevoflurano para laparoscopia ginecologica

Backgrounds and Objectives: Both continuous venous anesthesia with propofol and inhalational anesthesia with sevoflurane propitiate fast arousal with few side effects. The aim of this study was to compare the arousal and post anesthestic recovery times in patients submitted to these two agents. Methods: Forty three patient aged 18 to 50 years, physical status I or II, submitted to gynecological laparoscopy were distributed in two groups: G1 - propofol in continuous infusion of 115 μg.kg -1.min -1 and G2 sevoflurane. All the patients were pre-medicated with 7.5 mg midazolam, sufentanil 0.5 μg.kg -1, propofol 2 mg.kg -1, atracurium 0.5 mg.kg -1, N 2O in 50% of oxygen in a no-rebreathing system. The depth of the anesthesia and arousal time were assessed by the Bispectral index (BIS). The time between end of anesthesia and eye opening, time for command response and time for orientation were also evaluated. Results: The times recorded in minutes were: G1 - eye opening 8.2 ± 2.9, command response 8.6 ± 3.1, orientation 9.8 ± 3.4, recovery 31.6 ± 3.8; G2 - eye opening 4.5 ± 3, command response 4.9 ± 3.4, orientation 6.2 ± 3.4, recovery 66 ± 8. Except the recovery time, all the values were larger in G1. Conclusions: Both intravenous propofol or inhalational sevoflurane were considered excellent anesthetic techniques as to recovery time and recovery room discharge. Sevoflurane provided an earlier arousal with a longer recovery room stay as compared to propofol.

Effects of glucose infusion on the endocrine, metabolic and cardiorespiratory responses to halothane anaesthesia of ponies

Glucose was infused intravenously into six ponies during halothane anaesthesia, to evaluate its effect on their endocrine response to anaesthesia. The ponies were premedicated with acepromazine, and anaesthesia was induced with thiopentone and maintained with halothane in oxygen for two hours. Glucose was infused to maintain the plasma glucose concentration above 20 mmol/litre. Anaesthesia was associated with hypothermia, a decrease in haematocrit, hypotension, hyperoxaemia, respiratory acidosis and an increase in the plasma concentrations of lactate and arginine vasopressin. The concentration of β-endorphin in plasma increased transiently after 20 minutes but there were no changes in concentrations of adrenocorticotrophic hormone, dynorphin, cortisol or catecholamines. These data suggest that the glucose infusion attenuated the normal adrenal response of ponies to halothane anaesthesia.

Investigation into the use of the Laryngeal Mask Airway in pentobarbital anesthetized dogs

Objective - To investigate the use of the laryngeal mask airway (LMA) in dogs. Study Design - Prospective experimental study. Animals - Eight healthy adult mixed breed dogs weighing from 15 to 20 kg. Methods - The dogs were anesthetized with intravenous pentobarbital. An LMA was introduced after the induction of anesthesia and 1 L/min O2 plus 1 L/min air was delivered using a circle anesthetic system. Respiratory rate, tidal volume, arterial O2 saturation (pulse oximetry), end tidal CO2, inspired fraction of O2, pulse rate, and mean arterial blood pressure were measured after the insertion of the LMA and 30, 60, 90, and 120 minutes afterwards. Results - There were no changes in respiratory rate, tidal volume, arterial O2 saturation, and pulse rate during anesthesia. End tidal CO2 decreased significantly by the end of anesthesia and ventilation appeared satisfactory. Conclusions - An LMA appeared to be an alternative option to maintain the patency of the airway in dogs. Clinical Relevance - This device may allow safe maintenance of an airway in dogs when intubation is difficult or when it interferes with the procedure (eg, cervical myelography). ©Copyright 1999 by The American College of Veterinary Surgeons.

Tracheobronchial consequences of the use of heat and moisture exchangers in dogs

Purpose: To determine the effect of heat and moisture exchange (HME) on the tracheobronchial tree (TBT) using a unidirectional anesthesic circuit with or without CO2 absorber and high or low fresh gas flow (FGF), in dogs. Methods: Thirty-two dogs were randomly allocated to four groups: G1 (n = 8) valvular circuit without CO2 absorber and high FGF (5 L·min-1); G2 (n = 8) as G1 with HME; G3 (n = 8) circuit with CO2 absorber with a low FGF (1 L·min-1); G4 (n = 8) as G3 with HME. Anesthesia was induced and maintained with pentobarbital. Tympanic temperature (TT), inhaled gas temperature (IGT), relative (RH) and absolute humidity (AH) of inhaled gas were measured at 15 (control), 60, 120 and 180 min of controlled ventilation. Dogs were euthanized and biopsies in the areas of TBT were performed by scanning electron microscopy. Results: The G2 and G4 groups showed the highest AH (>20 mgH2O·L-1) and G1 the lowest (< 10 mgH2O·L-1) and G3 was intermediate (<20 mgH2O·L-1) (P < 0.01). There was no difference of TT and IGT among groups. Alterations of the mucociliary system were greatest in G1, least in G2 and G4, and intermediate in G3. Conclusion: In dogs, introduction of HME to a unidirectional anesthetic circuit with/without CO2 absorber and high or low FGF preserved humidity of inspired gases. HME attenuated but did not prevent alterations of the mucociliary system of the TBT.

Titulacao do sevoflurano utilizando o indice bispectral em anestesia pediatrica. Influencia da medicacao pre-anestesica no tempo de despertar e no consumo de anestesico inalatorio

Background and Objectives - Sevoflurane is an inhalational anesthetic drug with low blood/gas solubility providing fast anesthesia induction and emergence. Its ability to maintain cardiovascular stability makes it ideal for pediatric anesthesia. The aim of this study was to evaluate hemodynamic stability, consumption of inhalational anesthetics and emergence time in children with and without premedication (midazolam or clonidine) anesthetized with sevoflurane titrated according to BIS monitoring. Methods - Participated in this study 30 patients aged 2 to 12 years, physical status ASA I, undergoing elective surgeries who were divided into 3 groups: G1 - without premedication, G2 - 0.5 mg.kg-1 oral midazolam, G3 - 4 μg.kg-1 oral clonidine 60 minutes before surgery. All patients received 30 μg.kg-1 alfentanil, 3 mg.kg-1 propofol, 0.5 mg.kg-1 atracurium, sevoflurane in different concentrations monitored by BIS (values close to 60) and N2O in a non rebreathing system. Systolic and diastolic blood pressure, heart rate, expired sevoflurane concentration (EC), sevoflurane consumption (ml.min-1) and emergence time were evaluated. Emergence time was defined as time elapsed between the end of anesthesia and patients' spontaneous movements trying to extubate themselves, crying and opening eyes and mouth. Results - There were no differences among groups as to systolic and diastolic blood pressure, EC, sevoflurane consumption and emergence time. Heart rate was lower in G3 group. Conclusions - Sevoflurane has provided hemodynamic stability. Premedication with clonidine and midazolam did not influence emergence time, inhaled anesthetic consumption or maintenance of anesthesia with sevoflurane. Anesthesia duration has also not influenced emergence time. Hypnosis monitoring was important for balancing anesthetic levels and this might have been responsible for the similarity of emergence times for all studied groups.

Tempo de latencia e duracao do efeito do brometo de rocuronio no paciente submetido ao transplante renal

Background and Objectives - Successful cadaver kidney transplantation relies on a fast procedure. Patients with chronic renal failure may present with a delayed gastric emptying making it critical a fast tracheal intubation and airway maintenance. Rocuronium a recently introduced nondepolarizing neuromuscular blocker with a fast onset. The aim of this study was to evaluate onset time and duration of rocuronium effects in patients undergoing renal transplantation. Methods - Sixty patients were allocated into two groups of 30: Group R (GR) = patients undergoing renal transplantation and Group N (GN) = patients with normal renal function. All patients were premedicated with oral midazolam (15 mg) and anesthesia was induced with 30 μg.kg-1 alfentanil, 0.3 mg.kg-1 etomidate and 0.6 mg.kg-1 rocuronium injected through a central venous catheter. neuromuscular block was monitored by acceleromyography in the ulnar nerve pathway. The following parameters were evaluated: time between administration of rocuronium and first twitch reduction to 5% after supra-maximal stimulation (T1) (onset time = OT); time for first twitch to return to 25% (clinical duration = R25); time elapsed between 25% and 75% recovery of first twitch (relaxation recovery time = R25-75). Heart rate (HR) and mean blood pressure (MBP) were recorded in 6 moments. Results - Median OT was 31 sec. in GR and 47 sec. in GN. Median R25 was 51.5 min in GR and 33.5 min in GN. Median R25-75 was 28 min in GR and 20 min in GN. MBP and HR were higher in GR. Tracheal intubation conditions were excellent for most patients in both groups. Conclusions - These results open the possibility of 0.6 mg.kg-1 rocuronium being injected through a central venous catheter when a faster onset is needed. Due to wide differences in individual responses, monitoring of neuromuscular block is recommended.