Showing papers in "Canadian Journal of Anaesthesia-journal Canadien D Anesthesie in 1982"
TL;DR: The data suggest that ketamine is a mild depressant of cerebral metabolic rate and has no other cerebral vascular effects.
Abstract: The effects of kelamine on cerebral blood flow (CBF), cerebral metabolic rate (CMRo2) and intracranial pressure (ICP) were evaluated in ventilated or spontaneously breathing goats after peripheral administration of 5mg.kg-1 and central administration of 0.1 -2.0 mg.
102 citations
TL;DR: The findings suggest that patients subjected to spinal fusion need not be awakened during operation for testing of cord function provided somatosensory evoked potentials are monitored and remain stable and Hypotension seems unlikely to increase the risk of neurological damage if spinal cord function is monitored.
Abstract: Twenty-four patients requiring spinal fusion with Harrington rod instrumentation were studied prospectively to determine the effects of moderate hypotension on blood loss, operating conditions, operating time and spinal cord function. Hypotension reduced blood loss and improved operating conditions but did not shorten operating time. Five patients had alterations in somatosensory cortical evoked potentials after straightening of the spine that prompted us to reverse hypotension (when present) and haemodilution, and then to do wake-up tests. All wake-up tests were normal and all evoked potential alterations resolved during operation. Hypotension seems unlikely to increase the risk of neurological damage if spinal cord function is monitored. Our findings suggest that patients subjected to spinal fusion need not be awakened during operation for testing of cord function provided somatosensory evoked potentials are monitored and remain stable.
68 citations
TL;DR: This study of 100 patients with Trisomy 21 (T21) indicates that the incidence of complications is low, however, the anaesthetist must understand the pathophysiology of T21 in order to provide optimal anaesthetic care.
Abstract: Down's Syndrome (Trisomy 21, T21) occurs in approximately 0.15 per cent of live births. In addition to the stigmata of the syndrome, other congenital defects are frequently found in these patients. Cardiac lesions are particularly prominent. To determine the complications associated with anaesthesia and surgery we examined the records of 100 consecutive patients (58 males, 42 females) who underwent surgery with general anaesthesia during a two year period, from March 1978-March 1980. In addition to the cardiac lesions, the low birth weight of Trisomy 21 infants, increased susceptibility to infections, atlanto-occipital dislocation, and reduced central nervous system catecholamine levels might be expected to result in an increased incidence of complications. This study of 100 patients with Trisomy 21 (T21) indicates that the incidence of complications is low. However, the anaesthetist must understand the pathophysiology of T21 in order to provide optimal anaesthetic care.
62 citations
TL;DR: Linear airway dimensions from incisor teeth to vocal cords were measured from radiographs and tracheal length was found to correlate best with body weight and strong positive correlation with height.
Abstract: Linear airway dimensions from incisor teeth to vocal cords were measured from radiographs. Normal children were slightly taller and heavier than children being treated for cleft palate and had significantly longer upper airway dimensions. Tracheal length was measured in 50 normal children breathing spontaneously under general anaesthesia and was found to correlate best with body weight. Strong positive correlation with height was also found. Data from normal children in these two studies were used to calculate the distance from lips to mid-trachea to determine optimal length for a tracheal tube. Previously published data on airway lengths in children are reviewed.
59 citations
TL;DR: For anaesthetists, direct enquiry into daytime and nightime sleep abnormalities and careful examination of the upper airway are important for preoperative detection of patients and especially patients with obstructive sleep apnoea who might present for anaesthesia and operation.
Abstract: The sleep apnoea syndrome is reviewed, defined, and classified. Particular emphasis is placed on the identification of a patient population that is prone to sleep apnoea and the diseases and syndromes that are associated with it. For anaesthetists, direct enquiry into daytime and nightime sleep abnormalities and careful examination of the upper airway are important for preoperative detection of these patients and especially patients with obstructive sleep apnoea who might present for anaesthesia and operation. A typical case is reported and details of the preoperative, peroperative and postoperative management are discussed.
58 citations
TL;DR: The authors studied the effectiveness of ephedrine given intramuscularly before epidural anaesthesia with bupivacaine 0.5 per cent in three groups of patients undergoing electivecaesarean section and found it did not lower the incidence of hypotension significantly and was associated with an increase in umbilical artery [H+] and decrease in pH.
Abstract: The authors studied the effectiveness of ephedrine given intramuscularly before epidural anaesthesia with bupivacaine 0.5 per cent in three groups of patients undergoing electivecaesarean section. The patients received intramuscular saline as a placebo, ephedrine 25 mg or ephedrine 50 mg, 15 to 30 minutes before anaesthesia. The incidence of hypotension was 8 to 12 per cent in all three groups. Prophylactic intramuscular ephedrine did not lower the incidence of hypotension significantly. Intramuscular ephedrine 50 mg caused a persistent hypertension in eight out of 12 patients and was associated with an increase in umbilical artery [H+] (decrease in pH). No differences were observed in other indices of neonatal well-being. The prophylactic use of intramuscular ephedrine before epidural anaesthesia for caesarean section is not recommended.
53 citations
TL;DR: One case of tympanic perforation and one case of haemotympanum are reported as examples of such consequences of middle ear pressure variations during inhalation of high concentrations of nitrous oxide.
Abstract: Many authors have reported middle ear pressure variations during inhalation of high concentrations of nitrous oxide. An on-going study on subjects anaesthetized with nitrous oxide and oxygen supplemented with halogens or narcotics and excluding operations on the ear enables us to register three typical curves of middle ear pressure according to the patency of the Eustachian tube. We recorded significant negative middle ear pressures during the recovery period when there was important obstruction of the Eustachian tube.
53 citations
TL;DR: Determination of serum CPK is very important before general anaesthesia and the caffeine sensitivity test of biopsied muscle fibers revealed an increase in sensitivity, although there was no sign of muscle rigidity during or after anaesthesia.
Abstract: We report a patient with Duchenne muscular dystrophy who developed malignant hyperpyrexia during general anaesthesia. During anaesthesia bradycardia was followed by ventricular fibrillation, on which ventricular flutter supervened and a body temperature rise of 0.6°C for 15 minutes, myoglobinuria and elevation of CPK level were observed. The caffeine sensitivity test of biopsied muscle fibers revealed an increase in sensitivity, although there was no sign of muscle rigidity during or after anaesthesia. Diagnosis of Duchenne muscular dystrophy was first established after the development of malignant hyperpyrexia in the present case as well as in previously reported cases. Determination of serum CPK is very important before general anaesthesia.
47 citations
TL;DR: The use of these agents to decrease the risk of acid pulmonary aspiration syndrome by no means obviates the need for proper anaesthesia technique during induction of anaesthesia, and ranitidine appears to be a better choice than Cimetidine in the doses studied.
Abstract: A comparative trial of the H2-receptor antagonists, Cimetidine and ranitidine, on gastric pH and volume, was conducted in 168 healthy patients coming to elective surgery. The drugs were administered in random fashion either intravenously (ranitidine 50 mg or 100 mg, Cimetidine 300 mg or placebo) or orally (ranitidine 150 mg, Cimetidine 300 mg or placebo). The patients received the drugs or placebo 45 minutes to five hours before operation. After induction of anaesthesia, a nasogastric tube was passed and the stomach contents were aspirated. The volume and pH were measured. Those patients receiving ranitidine 50 or 100 mg or Cimetidine 300 mg intravenously had statistically significantly higher gastric pH compared to those receiving placebo, but up to eight percent of patients had a pH less than 2.5. Oral administration of Cimetidine 300 mg or ranitidine 150 mg were also superior when compared to placebo. However, 25 per cent of the patients receiving oral Cimetidine had a pH less than 2.5; Cimetidine orally was statistically significantly inferior to ranitidine 100 mg given intravenously. We conclude that the intravenous use of either ranitidine or Cimetidine is an acceptable method to decrease the acidity of gastric contents before induction of anaesthesia. Orally, ranitidine appears to be a better choice than Cimetidine in the doses studied. Both ranitidine and Cimetidine need to be given at least 45 minutes before induction of anaesthesia to be effective; therefore the use of these agents to decrease the risk of acid pulmonary aspiration syndrome by no means obviates the need for proper anaesthesia technique during induction of anaesthesia.
46 citations
TL;DR: Suggestions are made concerning possible modification of the technique of anterior approach to the stellate ganglion, including test dose size, to reduce the incidence of inadvertent injection into the vertebral artery and subsequent central nervous system toxicity.
Abstract: Two case reports illustrate that low doses of local anaesthetics such as bupivacaine 2.5 mg and a mixture of bupivacaine 1.25 mg and lidocaine 5 mg can induce grand mal seizures if injected into the vertebral artery during stellate ganglion block. The effect of the dose of local anaesthetic agent and technique of administration into the stellate ganglion region discussed as is the relationship between vertebral artery blood flow and cerebral intravascular local anaesthetic concentration required to produce seizure activity. Suggestions are made concerning possible modification of the technique of anterior approach to the stellate ganglion, including test dose size, to reduce the incidence of inadvertent injection into the vertebral artery and subsequent central nervous system toxicity.
45 citations
TL;DR: Randomly selected trachéal tubes were used in 56 patients undergoing elective abdominal surgery, followed by direct questioning about sore throat on the first postoperative day, and the incidence of postoperative sore throat was 41 per cent with high volume low pressure cuffed tubes and 55 per percent with low volume high pressure cuffs.
Abstract: Recent reports of the incidence of postoperative sore throat following anaesthesia with tracheal intubation have claimed that low volume high pressure cuffs are preferable to those with high volume and low pressure. In this study similar methods were used for evaluating postoperative sore throat. Randomly selected tracheal tubes were used in 56 patients undergoing elective abdominal surgery, followed by direct questioning about sore throat on the first postoperative day. The incidence of postoperative sore throat was 41 per cent with high volume low pressure cuffed tubes and 55 per cent with low volume high pressure cuffed tubes. This difference is not statistically significant, but the tendency of the results is contradictory to those published earlier. The incidence of postoperative sore throat varies greatly if direct or indirect questioning is used and also varies between studies using the same method of questioning. Therefore the validity of this method for evaluating the influence of cuff design must be questioned. Postoperative sore throat is a symptom caused by many factors, such as the intubation procedure and the use of stylets or lubricants. The incidence of postoperative sore throat does not necessarily reflect damage caused by the tracheal tube cuff.
TL;DR: The data indicate that patients undergoing CABG operations taking propranolol require significantly less sufentanil for unconsciousness and the entire operation than patients not taking this drug, and had less hypertension during operation and thus required less supplements.
Abstract: We measured the dose of sufentanil required for unconsciousness as well as the entire operation in 44 patients (22 taking propranolol and 22 not taking propranolol) undergoing coronary artery bypass grafting (CABG) operations The incidence of hypertension during operation, requirements for supplements to treat hypertension and recovery times were also determined The data indicate that patients undergoing CABG operations taking propranolol require significantly less sufentanil for unconsciousness and the entire operation than patients not taking this drug In spite of requiring less sufentanil, patients taking propranolol had less hypertension during operation and thus required less supplements However recovery times in both groups were the same The results of this study may partially explain the varying incidence of hypertension reported during high dose fentanyl and other narcotic-oxygen anaesthetic techniques
TL;DR: The evidence suggests that all three agents - like thiopentone, halothane and enflurane — can impair the ventilatory response to isocapnic hypoxaemia in man, but that in relation to the carbon dioxide responses, the magnitude of this depressive effect varies.
Abstract: We compared the ventilatory response to isocapnic hypoxaemia with a standard response to hyperoxic hypercarbia in human subjects sedated with methoxyflurane, diethyl ether or nitrous oxide, or anaesthetized with methoxyflurane. Compared to the awake state, methoxyflurane 0.1 MAC sedation did not alter either response significantly; methoxyflurane 1.1 MAC anaesthesia depressed both, with a somewhat greater effect on the hypoxaemic response. Diethyl ether 0.1 MAC sedation reduced only the hypoxaemic response. Nitrous oxide 0.1 MAC reduced both hypoxaemic and carbon dioxide responses in parallel. The evidence suggests that all three agents - like thiopentone, halothane and enflurane - can impair the ventilatory response to isocapnic hypoxaemia in man, but that in relation to the carbon dioxide responses, the magnitude of this depressive effect varies. Halothane and enflurane are the most depressant, nitrous oxide and thiopentone the least, with methoxyflurane and diethyl ether appearing to be intermediate in effect.
TL;DR: The femoral nerve block was found to be useful for purposes of transportation and immobilization and is easy, safe, economical and most useful in emergency and poor risk patients.
Abstract: Twenty five adults and children with fractured shaft of femur were given femoral nerve block for pain relief. The block was found to be useful for purposes of transportation and immobilization. The pain relief was complete if the fracture site was in the middle third of the femoral shaft. The block is easy, safe, economical and most useful in emergency and poor risk patients.
TL;DR: The experience suggests that the epidural administration of morphine 4 mg may be a safe and reliable method of obtaining prolonged analgesia following Caesarean section.
Abstract: A randomized double blind placebo controlled study of the efficacy, duration and safety of epidural morphine for the management of pain after Caesarean section is reported. Three similar groups of patients received either 0, 4 mg or 8 mg of morphine sulphate in 10 ml of normal saline through an epidural catheter at the completion of the operation. Compared to the saline controls, both the 4 mg and 8 mg epidural morphine groups had significant pain relief as judged by an analogue pain scale (p < 0.001), the time to the first administration of narcotic analgesics (p < 0.001) and the amount of supplemental analgesic required in the first 36 hours after operation (p < 0.001). The side effects occurred in a dose-dependent fashion. Two patients who received epidural morphine 8 mg plus additional narcotic or antihistamine had reduced respiratory rates but were easily rousable. Our experience suggests that the epidural administration of morphine 4 mg may be a safe and reliable method of obtaining prolonged analgesia following Caesarean section.
TL;DR: Data indicate a lack of baroresponse in these preterm infants during light halothane anaesthesia which may alter their ability to maintain cardiac output when hypotensive, which is highly statistically significant in both instances.
Abstract: Anaesthetics depress the baroresponse of adults. If the same is true of infants, they will have difficulty maintaining their cardiac output if they become hypotensive because they are primarily rate dependent for cardiac output. The opportunity to test whether anaesthetics depress the baro-response of neonates arose while anaesthetizing preterm infants for ligation of patent ductus arteriosus.
TL;DR: It is concluded that reduction in body temperature influences the volume of distribution, rate of metabolism and excretion of phenobarbitone.
Abstract: Four critically injured children receiving large doses of phenobarbitone were studied during hypothermia (30 degrees - 31 degrees C) and at normal body temperature. The volume of distribution of phenobarbitone varied from 0.79 to 1.01 litres per kg and the serum t 1/2 ranged from 36.8 +/- 9.4 to 86.2 +/- 10.5 hrs. The percentage of dose recovered in urine in 16 days ranged from 40.5 to 65.5 per cent: 2.7 to 12.4 per cent as hydroxyphenobarbitone, 1.7 to 19.7 per cent as conjugated hydroxyphenobarbitone, 6.0 to 22.4 per cent as phenobarbitone-N-glucoside and 17.8 to 23.1 per cent as unchanged drug. After the body temperature was allowed to return to normal the rate of excretion of metabolites increased substantially and the rate of excretion of the unchanged drug decreased markedly. It is concluded that reduction in body temperature influences the volume of distribution, rate of metabolism and excretion of phenobarbitone.
TL;DR: Serum cholinesterase activities were measured for 270 minutes in patients following administration of neostigmine or pyridostIGmine for the reversal of pancuronium block in groups of seven patients each to assess the clinical relevance of these findings.
Abstract: Serum cholinesterase activities were measured for 270 minutes in patients following administration of neostigmine or pyridostigmine for the reversal of pancuronium block in groups of seven patients each. The enzyme activities were significantly depressed by neostigmine for four hours and by pyridostigmine throughout the whole period of study. Whereas the immediate effects of neostigmine were more intense, the effects of pyridostigmine beyond the first 30 minutes were more profound. The clinical relevance of these findings is discussed.
TL;DR: The scoring system proposed by Leventhal,et al may have been of some value in predicting whether or not a particular patient undergoing thymectomy was likely to need ventilation postoperatively, however, this scoring system was found to be of no value.
Abstract: In a recent report Leventhal, Orkin, and Hirsh described a scoring system felt to be of value in predicting the need for postoperative mechanical ventilation in patients with myasthenia gravis undergoing thymectomy. Leventhal, et al. identified four risk factors felt to have predictive value, namely: (1) duration of myasthenia gravis greater than or equal to 6 years, (2) chronic respiratory disease, (3) dose of pyridostigmine greater than or equal to 750 mg per day, and (4) vital capacity less than or equal to 2.9 litres. Forty-six patients with myasthenia gravis who received 68 general anaesthetics were studied retrospectively. They represented the past 10 years' anaesthetic experience with myasthenia gravis at the Vancouver General Hospital. The patients were divided into two groups: (1) those who underwent thymectomy, and (2) those who underwent procedures other than thymectomy. Using the risk factors of Leventhal, et al., a predictive score was assessed for each patient; the time of postoperative tracheal extubation was also noted for each patient. From this study it was concluded that the scoring system proposed by Leventhal, et al. may have been of some value in predicting whether or not a particular patient undergoing thymectomy was likely to need ventilation postoperatively. In 41 myasthenics who had procedures other than thymectomy, however, this scoring system was found to be of no value.
TL;DR: Two diagnostic tests for Malignant Hyperthermia (MH) are compared and contrasted - the Caffeine-Halothane Contracture Test and theCaffeine Skinned Fibre Tension Test - both shows a strongly positive relationship both with the occurrence of MH reactions and with each other.
Abstract: We have compared and contrasted two diagnostic tests for Malignant Hyperthermia (MH) -the Caffeine-Halothane Contracture Test and the Caffeine Skinned Fibre Tension Test. Both tests show a strongly positive relationship both with the occurrence of MH reactions and with each other. The former test is more rapid and requires less skill. The latter test can be performed on much less muscle and permits storage of the muscle over prolonged periods of time.
TL;DR: The authors speculate that aminophylline, which is a known inhibitor of the enzyme phosphodiesterase, raised thelevel of c-AMP and, in turn, the level of acetylcholine at the neuromuscular junction and thus antagonized the blocking effect of pancuronium.
Abstract: A 17 year old male with a history of bronchial asthma was admitted to the intensive care unit in severe respiratory distress. During a two week period of intensive respiratory care he received large doses of aminophylline and corticosteroids. In addition, pancuronium was given to facilitate ventilation and to reduce airway pressure. Large doses of pancuronium, as much as 5 mg/hr, were required to stop spontaneous respiratory efforts and restlessness. The total pancuronium dose given during the two week period was 800 mg. One hour after pancuronium was discontinued the patient could open his eyes and move his lips. Peripheral nerve stimulation indicated partial paralysis which improved promptly following a test dose of edrophonium.
TL;DR: A pre-shaped, pre-cut paediatric orotracheal tube was designed from data obtained from a study of airway length and configuration in children of various ages, intended for use in head and neck, and pharyngeal surgery.
Abstract: A pre-shaped, pre-cut paediatric orotracheal tube was designed from data obtained from a study of airway length and configuration in children of various ages. This tube is intended for use in head and neck, and pharyngeal surgery.
TL;DR: Rigidity following succinylcholine should prompt the clinician to consider malignant hyperthermia but has been associated with other myopathic conditions as discussed.
Abstract: We evaluated six boys who had developed isolated masseter muscle spasm following intravenous succinylcholine. All were receiving halothane by inhalation.In vitro muscle contracture tests utilizing halothane and caffeine were performed. Four of the six boys had contracture responses similar to those of malignant hyperthermia susceptible patients. Rigidity following succinylcholine should prompt the clinician to consider malignant hyperthermia but has been associated with other myopathic conditions as discussed.
TL;DR: A significant decrease in ionized calcium occurred which preceded the maximal reduction in cardiac output and systemic arterial pressure and the clinical implications of these results are discussed.
Abstract: Ten anaesthetized, heparinized healthy adult dogs were infused with protamine sulphate 3 mg.kg-1 and plasma ionized calcium was measured. A significant (p < 0.01) decrease in ionized calcium occurred which preceded the maximal reduction in cardiac output and systemic arterial pressure. The clinical implications of these results are discussed.
TL;DR: Because of its ease of use and short duration of action, Entonox appears to be well suited for the treatment of pre-hospital pain by Emergency Medical Technicians.
Abstract: Pre-hospital self-administered analgesia using a 50:50 mixture of nitrous oxide and oxygen (Entonox) was evaluated in 240 patients. Of these, 93.4 per cent experienced either complete or partial relief from traumatic, chest, abdominal or back pain. Drowsiness was the most common side effect noted. No complications occurred during delivery of the mixture. Attention is drawn to the effect of extreme temperatures on the Entonox mixture and recommendations are made with respect to its use below-freezing climates. Because of its ease of use and short duration of action, Entonox appears to be well suited for the treatment of pre-hospital pain by Emergency Medical Technicians.
TL;DR: Charts of nine patients with Duchenne and one with Becker’s muscular dystrophy who had undergone spinal fusion and Harrington rod insertion for scoliosis were reviewed retrospectively and a vital capacity of at least 20 ml-kg-1 would appear to be adequate in patients with muscular Dystrophy requiring Harrington rods insertion.
Abstract: Charts of nine patients with Duchenne and one with Becker’s muscular dystrophy who had undergone spinal fusion and Harrington rod insertion for scoliosis were reviewed retrospectively. The mean age was 15 years and mean angle of scoliosis was 69 degrees. Preoperative pulmonary function studies showed a restrictive defect with a mean vital capacity of 1.3 ± 0.69 litres, 35 ± 20 per cent of predicted value, 33 ± 20 ml-kg-1 and a mean inspiratory capacity of 0.99 ±0.5 litres, 23 ± 13 ml.kg-1. There were no anaesthetic complications during operation and obstructive cardiomyopathy, hyperpyrexia, hyperkalaemia and rhabdomyolysis were not problems. Succinylcholine was avoided. One patient developed an arrhythmia postoperatively and one patient whose postoperative problems included tracheostomy, pneumonia and sepsis could not be weaned from the ventilator and died 11 weeks after operation. As assessing risk and survival of the operation depends on objective pulmonary function, a vital capacity of at least 20 ml-kg-1 in the range of 30 per cent of predicted volume with an inspiratory capacity of at least 15 ml.kg-1 would appear to be adequate in patients with muscular dystrophy requiring Harrington rod insertion. Other factors including the rapidity of progression of the muscular disease, other respiratory and cardiovascular problems, and disease such as obesity should also be considered.
TL;DR: The onset of analgesia produced by the epidural injection of β-endorphin was slower and the duration less than those observed after intrathecal injection.
Abstract: Epidural administration of 3 mg of synthetic beta-endorphin produced analgesia in 10 patients with intractable pain due to disseminated cancer. Mean onset of relief of pain was 24 +/- 3 minutes and the mean duration of analgesia was 19 +/- 3 hours. The onset of analgesia produced by the epidural injection of beta-endorphin was slower and the duration less than those observed after intrathecal injection.
TL;DR: The present study attempts to determine if malignant hyperthermia susceptibility (MHS) is limited to muscles composed predominantly of a single major fiber type, and finds that the greater contracture response of MHS trapezius to halothane or to caffeine is more biochemical than physiological in origin.
Abstract: The present study attempts to determine if malignant hyperthermia susceptibility (MHS) is limited to muscles composed predominantly of a single major fiber type. The MHS trapezius muscle (49 per cent type 1 and 51 per cent type 2 fibers) has greater abnormal contracture response to halothane or to caffeine than does MHS gracilis (11 per cent type 1 and 80 per cent type 2 fibers). The dynamic properties (contraction and relaxation times) of MHS trapezius and MHS gracilis are similar, suggesting that the greater contracture response of MHS trapezius to halothane or to caffeine is more biochemical than physiological in origin. The results of this study are discussed in relevance to the diagnosis and to aetiologic investigation of malignant hyperthermia.
TL;DR: Controversial aspects of malignant hyperthermia management such as the safety of calcium and catechol inotropes are discussed in relationship to the successful use of cardio-pulmonary bypass in a patient with biopsy-proven malignanthyperthermia.
Abstract: The anaesthetic management of cardiopulmonary bypass (CPB) for a patient with biopsy-proven malignant hyperthermia is reported. Specific changes in the technique used, such as venting the oxygenator before use, monitoring mixed venous Po2 and PCO2, as well as the safety of cold hyperkalaemic cardioplegia are described. Controversial aspects of malignant hyperthermia management such as the safety of calcium and catechol inotropes are discussed in relationship to the successful use of cardio-pulmonary bypass in our patient. We chose to treat left ventricular dysfunction by aggressive vasodilator (nitroglycerine) therapy. We detected no myocardial or respiratory depression secondary to dantrolene therapy either before or after operation.
TL;DR: This method of administration of ORG NC45 assures a stable level of curarization without side-effects, however, because of the different individual levels of sensitivity which were noted, this mode of administration requires careful monitoring to avoid inappropriate dosage.
Abstract: In order to obtain stable muscle relaxation for intra-abdominal operation, a continuous demand perfusion of ORG NC45 was administered following a loading dose of 0.07 mg . kg-1. The patients had previously been anaesthetized with methohexitone, fentanyl and nitrous oxide. The perfusion rate of ORG NC45 was regulated so that the mechanical muscular response of the adductor pollicis following a supra-maximal stimulation of the ulnar nerve was maintained at 10 per cent of its initial value. The level of relaxation thus obtained was always adequate for the surgeons. During the course of the operation the requirement for more relaxant decreased progressively, becoming stable after one half hour. Nevertheless, during stable administration, individual variations were quite marked, being 44 to 483 micrograms/M2 BSA/10 min (average 225 micrograms/M2 BSA/10 min). The duration of the infusion varied from 60 to 107 minutes (average 103 minutes). After its termination the time taken from recovery varied between 3 and 82 minutes (average 27 minutes). Having regained a single twitch height of 75 per cent patients awoke rapidly after the administration of nitrous oxide was terminated. No signs of recurarization were noticed in any of the patients. In conclusion, this method of administration of ORG NC45 assures a stable level of curarization without side-effects. However, because of the different individual levels of sensitivity which were noted, this mode of administration requires careful monitoring to avoid inappropriate dosage.