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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.

An adapter (Sunnybrook Fibreoptic Adapter) is described which permits the use of intermittent positive pressure ventilation during bronchoscopy with the flexible fibreoptic bronchoscope, under general anaesthesia or in patients in respiratory failure maintained on ventilators.

We measured plasma cortisol levels during surgery in seven neonates within ten days after birth and in 14 infants ranging in age from three months to 11 months. The 14 infants were divided into two groups; Group I included eight infants in whom general anaesthesia was maintained with oxygen, nitrous oxide and a muscle relaxant, Group II, six infants in whom general anaesthesia was maintained with oxygen, nitrous oxide, halothane and a muscle relaxant. In the neonates, the changes in mean plasma cortisol levels during anaesthesia were not statistically significant. In both Group I and Group II infants, the mean cortisol levels gradually rose during anaesthesia, but the initial rise in plasma cortisol levels was suppressed in the patients who received halothane.

The effects of anaesthetic agents, per se, on the asphyxiated foetus are difficult to quantitate clinically. Anaesthesia is often necessary in foetal distress, however, to effect a rapid delivery. To investigate the effect of general anaesthetic agents commonly used for Caesarean section we administered these agents to 18 chronically prepared pregnant ewes with asphyxiated foetuses in utero. The foetuses were asphyxiated by partial occlusion of the umbilical cord until foetal arterial pH had decreased from 7.30 to a range of 7.08-7.13. The animals were divided into three groups: Group A which received no anaesthesia and thus served as a control, Group B which received thiopentone (3 mg . kg-1) intravenously followed by 50 per cent nitrous oxide and 0.5 per cent halothane in oxygen for 15 minutes, and Group C which received thiopentone (3 mg . kg-1) followed by one per cent halothane in oxygen for 15 minutes. Foetal cerebral, myocardial, and renal blood flows were measured by injection of radioactive microspheres after production of asphyxia and after 5 and 15 minutes of anaesthesia. General anaesthesia in both groups B and C abolished the hypertension and bradycardia produced by foetal asphyxia secondary to umbilical cord occlusion. There were no significant differences between Groups B and C in foetal pH, PCO2, or PO2. Two foetuses in the nitrous oxide group died after ten minutes of anesthesia, but the aetiology of the sudden demise is unclear. We conclude that general anaesthesia abolishes the foetal response to umbilical cord occlusion and does not improve foetal oxygenation or acid-base status.

Sixteen patients were studied to determine if naloxone could be shown to affect general anaesthesia with halothane and oxygen or nitrous oxide and oxygen with halothane. Changes in blood pressure, pulse rate, electroencephalogram and evidence of physical response were observed. The end-tidal halothane and carbon dioxide were controlled. The temperature and blood gases were held constant, as was the degree of neuromuscular blockade. Naloxone 1.2 mg was administered during general anaesthesia with either halothane in oxygen or halothane with nitrous oxide to 16 patients who were premedicated without a narcotic. No significant responses were recorded.

Seventy-three patients were studied during and after anaesthesia with either alfentanil or halothanefor surgical procedures of short duration. The procedures were minor gynaecological or minor urological procedures, involving males and females between the ages of 21 and 86 years. After pre-medication with lorazepam, anaesthesia was induced with methohexitone and continued with nitrous oxide and oxygen, supplemented with halo-thane (34 patients) or alfentanil (39 patients). Anaesthesia was generally smooth and uncomplicated except that at induction 22 of the patients receiving alfentanil became apnoeic for longer than 30 seconds. Spontaneous respiration resumed without the need for naloxone in any patients. After surgery, recovery of consciousness was significantly more rapid after alfentanil than after halo-thane (5.6 minutes versus 10.1 minutes). This study demonstrates that alfentanil can be a suitable alternative to conventional general anaesthesia for short cases and may have a useful place when rapid recovery and turnover of cases is important.

Thirty patients received general anaesthesia for forty intralaryngeal operations using a laser beam. The essential requirements for the anaesthetic management are: (1) Anaesthetic agents should be non-flammable. (2) Small diameter red rubber cuffed tracheal tubes provide maximum working space for the surgeon, facilitate controlled ventilation and minimize the explosion hazard of anaesthetic gases in the vicinity of the laser beam. (3) Continuous muscle relaxation of head and neck and of laryngeal muscles facilitates the instrumentation and lasing of lesions of vocal cords which are thus rendered fixed and immobile.

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.

Sixteen extremely obese patients were anaesthetized for intestinal short circuiting operations. Severe obesity may cause pathological cardio-pulmonary changes. Cardiovascular alterations include increased systemic, pulmonary artery and pulmonary capillary venous pressure. Cardiac output, total blood volume and left ventricular work increase. Expiratory reserve volume and consequently functional residual capacity decrease with gross obesity. Functional residual capacity falls below closing volume and inspired gas may be distributed to non-dependent lung zones, resulting in decreased ventilation/perfusion ratios and arterial hypoxaemia. Low total respiratory compliance increases the oxygen cost of the work of breathing. Obesity may change the dose requirements for regional anaesthesia and long-acting muscle relaxants. General anaesthesia may also reduce functional residual capacity. We used a technique of anaesthesia which consisted of epidural analgesia with intra-operative mechanical ventilation and which specifically avoided volatile inhalation agents and long-acting muscle relaxants. All patients were extubated immediately after operation and returned to the recovery room for an average duration of 26 hours. Post-operative treatment included humidified oxygen, chest physiotherapy and elevation of the head of the bed to 45 degrees. Each patient's respiratory progress was monitored by repeated determinations of arterial blood gases and vital capacity and by serial chest X-rays. None of the patients in this group required post-operative tracheal intubation and mechanical ventilation.

With the advent of surgery under the operating microscope microvascular surgical techniques requiring prolonged anaesthesia have greatly increased in number. Local anaesthetic techniques, whilst often producing excellent surgical conditions, are limited by the duration of action of the anaesthetic agents and by the ability of the patient to remain still, often in uncomfortable positions, for periods of up to twenty hours. The use of indwelling catheters as a means of prolonging the duration of nerve blocks is discussed along with methods of sedation or general anaesthesia to enable the patient to tolerate lengthy surgical intervention. Present general anaesthetic techniques may not be ideally suited to long surgical procedures. The problems and possible alternatives are discussed. Sympathetic ganglion blockade, intravenous regional blockade and systemic vasodilator therapy are discussed as a means of improving the success rate of these procedures. The general principles of patient management such as fluid balance, temperature control, patient positioning and control of the operating room environment assume a much greater significance when related to the provision of prolonged general anaesthesia, whilst the effect of extended periods of work on operating personnel must also be considered.

Sixty-four cases of posterior lumbar extension osteotomy performed at the Toronto East General Hospital between 1969 and 1983 are reviewed. The anaesthetic management is presented. The procedure was performed with local infiltration anaesthesia, heavy sedation and a brief period of general anaesthesia induced with nitrous oxide, halothane or ketamine. Five stages in the anaesthetic management are distinguished, each in relation to a phase of the surgical procedure and drug usage. A method of supporting these deformed patients in the prone position in moulded plaster casts is described. Anaesthetic and surgical complications and postoperative psychological disturbances are described and discussed. It is suggested that caudal epidural opioid or local anaesthetic analgesia be explored as an aid in the management of these patients.

Anaesthesia-induced rhabdomyolysis (AIR) is a rare but serious complication of general anaesthesia. We report the occurrence of this event in a previously healthy three-year-old male, with a strongly positive family history of Duchenne muscular dystrophy. Following an uneventful anaesthetic, which included succinylcholine, myoglobinuria developed and led to renal failure which fortunately reversed with conservative treatment. Based on review of reports of similar cases, it is clear that succinylcholine should be avoided in paediatric patients with known myopathy or at high risk for latent myopathy.

EXCEPT WITH DIETIIYL ETHER, no appreciable metabolic disturbances develop during general anaesthesia even with mild I to severe ~ hypoxia (15 per cent and 10 per cent oxygen) for 90 minutes, provided that normal pulmonary ventilation is maintained. In a comparative evaluation of enflurane and isoflurane, we did not observe a deleterious circulatory response in dogs subjected to 30 minutes of apnoea induced by anaesthesia plus muscle relaxants, with oxygen insufflation ("apnoeie oxygenation"). All of the animals survived the test. 3 Thereupon we attempted a crossover study to determine the physiological and biochemical effects of general anaesthesia in dogs with acute hypoxia (8 per cent to 10 per cent inspired oxygen concentration) for 90 minutes with spontaneous breathing. The original design for the investigation was abandoned because most of the animals did not survive. Review of the data suggested several factors contributory to the high mortality. The depth and duration of anaesthesia was too great to permit adequate pulmonary ventilation and optimal myocardial contractility. Blood volume was significantly reduced by sampling for laboratory tests. Liver glycogen stores and blood sugar were depleted and serum potassium and plasma insulin were reduced. The degree of hypoxia was evidently more than a dog's heart could tolerate during deep anaesthesia with spontaneous breathing. 4,5 This report describes a modified experimental approach and compares the response to enflurane and isoflurane with the responses to seven other inhalation anaesthetics and two parenteral anaesthetics.

This study determined the cardiovascular effects of percutaneous radiofrequency coagulation of the Gasserian ganglion, performed under neuroleptanalgesia and intermittent ultrashort-acting barbiturate anaesthesia. Twelve ASA physical status class II patients were studied. Highly significant increases in mean heart rate and arterial blood pressure followed the insertion of the cannula electrode into the Gasserian ganglion (p less than 0.001). In six randomly assigned patients severe tachycardia and hypertension also accompanied the progress of the thermal lesion (p less than 0.0001). Three patients developed premature ventricular contractions, and two developed significant ST segment depression. Intravenous nitroglycerin, used during current generation, successfully controlled the hypertensive response in the other six patients. In percutaneous thermocoagulation of the Gasserian ganglion the patient's co-operation is essential. In addition to providing suitable operating conditions for both surgeons and patient, we should also be able to maintain normal and stable cardiovascular haemodynamics. Intravenous nitroglycerin used as an adjunct to light general anaesthesia safely maintained intraoperative normotension. It is also suggested that patients with coronary artery disease be adequately monitored and protected during the procedure.

The effects of dobutamine, a new catecholamine, have been studied during anaesthesia with halothane, halothane and nitrous oxide and alphaprodine. Renal blood flow is increased by dobutamine as are mean arterial pressure and heart rate. The increase in rate is less marked during alphaprodine anaesthesia than when halothane is administered. Dobutamine may prove a useful agent in the management of acute circulatory failure but it is capable of inducing dysrhythmias under the conditions of these experiments.

A young healthy male, who had three consecutive episodes of postoperative hyperthermia was anaesthetized with special precautions to prevent malignant hyperthermia. Despite neuroleptic anaesthesia and dantrolene pretreatment, the patient experienced post-anaesthetic hyperthermia. The patient's clinical picture was almost identical to the symptoms experienced by two of his maternal relatives. All three experienced nausea, vomiting, muscle cramps and high fever which occurred between five to seven hours after general anaesthesia. The serum potassium (K) and creatinine phosphokinase (CPK) levels determined during the hyperthermic episode and on the next day were not elevated. On the basis of the patient's family history, his clinical picture, and his laboratory data, we speculate that this patient might have a form of malignant hyperthermia or a possible new variant.

CENERAL ANAESTHESIA 1-~ may be associated with an ineflqcient gas exchange cansing an increased alveolar-arterial oxygen tension difference (AaDo,,). Current evidence favors primarily mechanical causes 4,~, but the possibility of different pharmacological effects from anaesthetic agents has not been evaluated. The purpose of the present studies was to determine whether an inefficient oxygen exchange was an inevitable accompaniment of general anaesthesia, and also to compare the effects of two induction agents on the subsequent course of anaesthesia.

beta-endorphin, administered into the cerebral ventricles of rats, provokes a sequence of behavioural and electroencephalographic (EEG) responses similar to those observed with general anaesthetics used clinically. Initial behavioural and EEG excitation, motor incoordination and exaggerated responsiveness to sensory stimuli are followed by a stage of rigid immobility with maintenance of local reflexes (withdrawal, corneal) and EEG arousal in response to stimulation. Finally, there is immobility associated with both EEG and behavioural unresponsiveness to severely noxious stimuli. Such a state of unconsciousness with complete analgesia defines general anaesthesia. This state was completely and rapidly reversed by the specific opiate antagonist, naloxone. The induction of general anaesthesia by a water-soluble neurohormonal peptide acting at specific receptor sites has important implications for traditional theories of anaesthesia.

Twenty severely pre-eclamptic patients requiring caesarean section for delivery were allocated to two groups. One group received epidural anaesthesia consisting of either 20 ml of bupivacaine 0.75 per cent at L3-4 or 12ml at Ll-2. The other group received general anaesthesia consisting of thiopentone, 40 per cent nitrous oxide and halothane 0.5 per cent. Mean arterial pressure (MAP), pulmonary artery pressure (PAP), pulmonary wedge pressure (PWP), and central venous pressure (CVP) were recorded at five-minute intervals for at least 60 minutes before operation and at least every two minutes during anaesthesia. Patients receiving general anaesthesia had pressures recorded every minute during tracheal intubation and extubation. There was a mean increase of MAP of 45 mm Hg, of PAP 20 mm Hg, and PWP 20mm Hg during intubation and extubation. Apart from a slight mean fall in MAP the parturients receiving epidural anaesthesia showed little change in these cardiovascular parameters. It is concluded that tracheal intubation of patients with gestational hypertension produces an increase in MAP, PAP, and PWP which can lead to a significant risk of cerebral haemorrhage and pulmonary oedema. The value and dangers of using short-acting hypotensive agents to prevent these episodes of hypertension has still to be assessed. With epidural anaesthesia there is a danger of hypotension which can be treated with intravenous fluid replacement and ephedrine.

A pregnant patient at 38 weeks gestation presented for a combined procedure of Caesarean section, tubal ligation and cerebral aneurysm clipping. Anaesthesia was induced with thiopental, succinylcholine was administered to facilitate tracheal intubation, and intravenous lidocaine and sodium nitroprusside were used to reduce the hypertensive response to tracheal intubation. Anaesthesia was maintained with nitrous oxide until delivery of the infant, after which time fentanyl, low-dose halothane and pancuronium were added for maintenance of anaesthesia during the neurosurgical procedure. Blood pressure was controlled during the case by administration of a sodium nitroprusside infusion and propranolol. Following completion of the surgical procedures, the patient promptly emerged from anaesthesia and was neurologically normal in the operating room. It is concluded that general anaesthesia can be used satisfactorily for a combined procedure of Caesarean section and cerebral aneurysm clipping.

The speed, side effects and cardiovascular changes associated with anaesthetic induction and endotracheal intubation following alfentanil (20 micrograms/kg/min, IV), thiopental (84 micrograms/kg/min, IV), etomidate (5 micrograms/kg/min, IV) and midazolam (20 micrograms/kg/min, IV) prior to halothane-nitrous oxide general anaesthesia were evaluated and compared in 80 patients undergoing elective general surgical operations. Anaesthetic induction was fastest with etomidate and thiopental (approximately one minute) and slowest with midazolam (about two minutes). Systolic arterial blood pressure (SBP) was decreased at the moment of unconsciousness with thiopental but unchanged with the other compounds. Heart rate (HR) was increased at unconsciousness with midazolam and thiopental but unchanged with etomidate and alfentanil. After intubation HR was increased in all groups except those induced with alfentanil. Arrhythmias were infrequent (5 per cent or less in all groups). Rigidity during induction only occurred with alfentanil (55 per cent) and pain on injection only with etomidate (35 per cent) and alfentanil (5 per cent). Postoperative vomiting was infrequent in all groups (15 per cent) except etomidate (55 per cent). No patient remembered any aspect of laryngoscopy or the operation and all rapidly regained consciousness at the end of operation. The results of this study demonstrate that with the exception of rigidity (which is easily overcome with succinylcholine) and a slightly slower onset of action, alfentanil compares favourably as an induction agent with thiopental and is better than midazolam and etomidate. Alfentanil is superior to all three other induction agents with respect to cardiovascular stability during induction and intubation.

Out-patient surgery for infants and children offers the advantages of minimal emotional upset, less risk of infection, and fiscal economy. Many different operations can be done in the out-patient department and most children can be accepted for general anaesthesia for these operations. Preparation of the child is similar to that required for in-patient surgery. Premedication is unnecessary and contraindicated. A variety of techniques may be selected for induction of anaesthesia without unduly prolonging recovery. General inhalation anaesthesia with halothane is preferred for maintenance. Careful tracheal intubation should be utilized whenever indicated. Regional analgesia has many advantages over narcotic analgesics in the treatment of post-operative pain. A follow-up service should be provided.

Anaesthetic management for Caesarean section in a pre-eclamptic patient with Ebstein's anomaly and a right to left intracardiac shunt was accomplished under general anaesthesia. Air bubbles in the venous line were meticulously eliminated to prevent paradoxical air emboli. A rapid sequence induction using standard doses of thiopentone and succinylcholine did not result in loss of consciousness and muscle relaxation was inadequate for endotracheal intubation. This problem must be anticipated in patients with extremely enlarged right atria and the dose of induction agents should be increased. Carefully controlled epidural anaesthesia may be used if the cardiac reserve is adequate.

The Wolff-Parkinson-White syndrome or its variant, the pre-excitation syndrome, are described in about 1.2 per 1000 of the population, so the anaesthetic management of patients with this syndrome is important. Our experience is reported in 15 elective operations on seven patients with pre-excitation syndrome. The most significant feature is the occurrence of variation of the morphology of QRS complexes. Rhythm disturbance most commonly encountered is supraventricular tachycardia, but different cardiac arrhythmias may occur and sometimes these are fatal. In our study, major complications or cardiac arrhythmias did not occur. With regard to the anaesthetic technique, care should be taken not to produce tachycardia. Atropine is not absolutely contraindicated for premedication. Preoperative use of propranolol or of quinidine is questionable.

Oscillometry using an automatic monitor was compared with invasive blood pressure monitoring in 21 patients scheduled for surgery under general anaesthesia with deliberate hypotension. Six ranges of mean blood pressure measurements were studied, two of which were hypotensive. An excellent correlation was found between the two methods (systolic: r = 0.94; mean: r = 0.93; diastolic: r = 0.88) but there was a large variability among individual subjects. For systolic, diastolic and mean intra-arterial readings above an approximative value of 10.64 KPa (80 mmHg), the oscillometric monitor was found to underestimate blood pressure. Inversely, it was found to overestimate blood pressure for intra-arterial readings under the approximative value of 10.8 KPa (80 mmHg). We conclude that the non-invasive monitor represents a good trend estimation of the invasive radial blood pressure technique, but that wide inter-individual variability and the overestimation of blood pressure below an approximative value of 10.64 KPa (80 mmHg) precludes interchange of techniques when absolute values are considered, especially during controlled hypotension. However, oscillometry could represent a better estimate of central aortic pressure.

The effectiveness and safety of the Carden tube-oxygen injector system for ventilation was studied in 18 hlgh-rlsk patients with obstructive airways disease during mlcrolaryngeal surgery. Blood gas studies during operation demonstrated a mean Pao2 of 65.6 kPa (493 torr) and a mean Paco~Of4.5 kPa (34 tort) during mechanical ventilation. No serious complications were noted during operation. Fifty per cent of the patients had postoperative hypercapnia and in two the trachea was re-intubated. Airway maintenance and ventilation are discussed in detail and it is concluded that the Carden tube-oxygen injector system is a safe and convenient method for ventilating the lungs of patients with pulmonary disease who require microlaryngeal surgery. MECHANICAL VENTILATION of patients undergoing microlaryngoscop y or laryngeal microsurgery under general anaesthesia poses special problems for both anaesthetist and surgeon. Effective airway control, adequate ventilation and prevention of aspiration compete for primacy with good visibility and surgical access. Many techniques have been devised to meet anaesthetic and surgical requirements. These include reinforced tracheal tubes ~-3 and high-pressure gas injection through ventilating attachments to laryngoscopes or bronchoscopes 4'5 through small bore catheters 6-7 through lrans-tracheal catheters or cricothyroid needles s'9 or through the Carden tube ~~ and modifications. ~ In many centres these "venturi" or "injector" methods are replacing conventional spontaneous ventilation techniques for airway endoscopy. The Carden tube, first described in 1973, ~~ has many desirable properties and, since becoming commercially available, is now in widespread use. It allows for unimpeded surgical access while providing excellent airway anti ventilation control when used with a highpressure gas source. Some difficulties remain even when using the Carden tube. It has been claimed that the tube is difficult to insert. ~2 Many of the patients requiring laryngeal surgery are heavy smokers with significant pulmonary disease. It has never been shown that ventilation with this system is

Cimetidine 400 mg was administered intramuscularly 60 minutes before the beginning of general anaesthesia. The double blind experiment was conducted on 84 patients divided in two groups: cimetidine and control. There was no difference in gastric fluid volume between the two groups during general anaesthesia, but acid secretion decreased significantly in the cimetidine group. Values of pH lower than 2.5 were observed in 33.3 per cent at induction and 34 per cent at recovery in the control group against 14.6 per cent and 0 per cent in the cimetidine group. Clinical tolerance to cimetidine was studied in 100 patients during operation. Cimetidine did not alter pharmacological action of usual anaesthetics. There were no significant changes in cardiovascular and electrocardiographic data.

General anaesthesia with Althesin was administered on two occasions to a patient who was identified as susceptible to malignant hyperthermia, in whom there was identified familial subclinical myopathy and once in another patient suffering from arthrogryposis multiplex congenita with a history of fever associated with two previous anaesthetics. In the first patient halothane was administered by accident in association with the Althesin, but no hyperpyrexia occurred. In the second instance nitrous oxide-oxygen and halothane were associated purposely with Althesin. In none of these cases was there any rise in temperature, muscle rigor or elevation of the serum CPK level. This experience corroborates the experimental evidence of Hall, et al.10 and Harrison, who reported that Althesin prevented the onset of hyperthermia, and the clinical reports of Page and Judelman. Althesin can be assumed to be an effective anaesthetic for malignant hyperthermia susceptible patients.

We measured occlusion pressure, tidal volume, frequency, and the duration of the ventilatory phases in twenty-eight patients before and immediately after induction of anaesthesia by thiopentone. From these measurements we derived mean inspiratory flow rate and "effective" impedance to flow. Occlusion pressure was generally, but not universally, less after induction. Mean inspiratory flow rate was reduced due to a combination of smaller tidal volume and shorter duration of inspiration. This was noted in all twenty-eight patients, as was a clearcut increase in "effective" impedance to flow. These results suggest an important mechanical component to the reduced ventilation noted following induction of general anaesthesia.

Studies were carried out on 22 large, male, mongrel dogs at two-week intervals, in a crossover design, to determine the metabolic, blood-gas and cardiovascular effects, and the rate of recovery to steady ambulation from a surgical depth of general anaesthesia administered with passive hyperventilation. To prepare the animal, induction of anaesthesia was accomplished with 20 mg/kg body weight of 2 per cent thiopentone, tracheal intubation and inhalation of 50 per cent nitrous oxide and oxygen. After attachment of recording equipment and drawing of control blood samples, a respirator was attached to the anaesthetic circuit to provide passive hyperventilation by providing pulmonary ventilation of 15 ml/kg body weight at the rate of approximately 25 cycles per minute for 90 minutes, adding an anaesthetic concentration of methoxyflurane, chloroform, trichlorethylene, halothane, halothane-ether, azeotrope, isoflurane, cnflurane, diethyl ether, or fluorexcne from an out-of-circuit calibrated vapourizer. Thiopentone and Innovar were also tested and were given by an intravenous drip infusion. Nitrous oxide 50 per cent was given with 50 per cent oxygen with all the maintenance agents. No muscle relaxants were used and no stimulants were administered at the end of the test period.

A report is presented of a questionnaire survey of obstetrical anaesthesia practice patterns, academic structure, resident teaching and research programmes in Canadian University Departments of Anaesthesia. Replies were received from 13 of the 16 departments, representing 24 university-affiliated hospitals. It is apparent that the majority of these hospitals do not have adequate obstetrical anaesthesia coverage. In most instances the delivery suite is covered by the anaesthetists on duty in the operating rooms. While epidural analgesia is widely used during labour, there are some hospitals where it still has a limited use, or is not used at all. Caesarean sections are still largely done under general anaesthesia in most reporting hospitals, with a few institutions reporting an increasing use of regional (mainly epidural) anaesthesia. Resident training in this branch of anaesthesia is felt to be deficient, based on the reports from many hospitals that resident staff are frequently not in attendance at deliveries; and on the evident failure in the majority of institutions to utilize their clinical material for teaching purposes. Research programmes in obstetrical anaesthesia are rare. The most common reason cited was the difficulty experienced in obtaining research funds. It is suggested that the major problems in obstetrical anaesthesia service, teaching and research are: It is recommended that consideration be given to

The effects of succinylcholine (1.5 mg X kg-1 IV) administered five minutes after a defasciculating dose of curare (0.05 mg X kg-1 IV), were compared with the effects of atracurium (0.5 mg X kg-1 IV) on intracranial pressure (ICP) in 13 cynomolgus monkeys with intracranial hypertension (ICP approximately 25 mmHg). Neither succinylcholine nor atracurium increased ICP during general anaesthesia with 60 per cent N2O/O2, 0.5-1 per cent halothane. During a rapid sequence induction and intubation with thiopentone 5 mg X kg-1 IV, ICP increased equally with intubation following both atracurium (25 +/- 1 to 32 +/- 2 mmHg) and succinylcholine (25 +/- 1 to 31 +/- 2 mmHg) (p less than 0.05). Intubation was also associated with significant increases in PaCO2, CVP and MAP. We conclude that in this primate model of intracranial hypertension, neither atracurium nor succinylcholine (when given following a defasciculating dose of curare) elevates ICP. In terms of the elevation of ICP associated with intubation, atracurium was found to offer no advantage over succinylcholine.

One hundred Nigerian patients presenting for emergency caesarian section were interviewed within the first 24 hours post-operatively. The purpose was to deter-mine the incidence of awareness and dreams. The standard anaesthetic technique consisted of atropine 0.6 mg and thiopentone 250 mg given intravenously at the time of induction, suxamethonium bromide 40 mg intravenously to facilitate tracheal intubation and nitrous oxide/oxygen/pancuronium for maintenance. The incidence of awareness was 4 per cent while the incidence of dreaming was 17 per cent. Most (94 per cent) of the patients said they dreamed only occasionally at home and of these, 15 per cent claimed they dreamed more frequently when pregnant than when not pregnant.

The effects of physostigmine on reversal of post-operative somnolence following general anaesthesia were evaluated in 187 patients. Significant reversal of anaesthetic-induced post-operative somnolence was observed in those patients receiving physostigmine when compared to a control group. These results suggest that general anaesthesia with halothane may be included in those situations where central nervous system depression may be reversed by administration of physostigmine. Cholinergic side-effects observed with physostigmine administration were minimal.

Light general anaesthesia combined with marked muscle paralysis can be used as the procedure while unpleasant and terrifying is not painful nor surgically stimulating. In addition the airway is well anaesthetized topically. Paralysis permits maximal control over the patient and the maintenance of position of the Carlens tube, in a situation where movement or coughing might be dangerous. Paralysis also maximizes lung-thorax compliance, reduces O2 consumption and permits lavage under light anaesthesia. The choice of maintenance anaesthetic appeared to be a negligible factor in the management of these patients. With the doses of ketamine employed, post-lavage CNS depression did not delay weaning and extubation. Dreaming, hallucinations and emergence delirium related to ketamine were not reported nor observed. The absence of these phenomena was probably related to the use of diazepam before and immediately after the lavage but prior to weaning from the respiratory support as suggested by Coppel,et al. 11 In our opinion either ketamine or halothane employed in these doses are suitable maintenance anaesthetics. The use of ketamine does avoid the controversial administration of two halothane anesthetics in close sequence.

Depending on the population characteristics, 12 to 80 per cent of patients undergoing elective surgery exceed the current risk criteria for aspiration pneumonitis (gastric volume greater than or equal to 0.4 ml.kg-1 and pH less than or equal to 2.5), in sharp contrast to the actual incidence of the disorder, estimated at 0.01 per cent. Improved specificity would likely result if the risk of regurgitation was also considered, in addition to the volume and pH criteria. As a first attempt to assess the risk of regurgitation under general anaesthesia, we measured the minimal gastric volume (VR) required to produce regurgitation in cats anaesthetized with ketamine. The mean was 20.8 ml.kg-1 (n = 7, range: 8-41, SD = 7.8). We conclude that the residual gastric volume needed to produce a regurgitation under general anaesthesia is at least 20 times greater than the volume required to produce pulmonary damage by intratracheal injection (0.3 ml.kg-1, assuming a pH of 2.5 or less).

Foetal heart rate and tocodynamic monitoring of the uterus was performed in five pregnant patients undergoing urgent or emergency surgery unrelated to their pregnancy. All received general anaesthesia with halothane or enflurane and nitrous oxide. The loss of beat-to-beat variation of the foetal heart rate was observed in all patients under general anaesthesia, and is probably normal for the anaesthetized foetus. Since continuous intraoperative monitoring of foetal heart rate in pregnant patients is technically feasible during peripheral surgery and during many intra-abdominal procedures, attempts should be made to monitor foetal heart rate in all anaesthetized parturients to assure that the anaesthetic is not causing foetal insult. Postoperative monitoring of uterine tone is useful in the diagnosis and treatment of postoperative premature labor.

Plasma levels of antidiuretic hormone (ADH) were evaluated in 40 adult patients during and after various types of anaesthesia and surgery. The plasma level of ADH increased significantly 30 minutes after the start of anaesthesia with diethyl-ether (3.7 times) and after thiopentone (1.5 times), but it increased insignificantly in neuroleptanaesthesia (2.4 times) and with halothane (1.3 times). The surgical stress evoked marked increases in plasma ADH levels especially at ten minutes after the skin incision. A slight increase in plasma ADH level still continued into the early post-operative days.

Some of the advantages and disadvantages of local and general anaesthesia for bronchoscopy have been discussed and the findings in a series of 275 cases reported. It is shown that general anaesthesia is preferable to a high percentage of patients, permitting an easier instrumentation and quicker examination and giving fewer complications of trauma, but the present technique, using succinylcholme and thiopentone, introduces several further complications, figures for which are given. It is suggested that, while each case should be considered on its merits, general anaesthesia will be the anaesthesia of choice in the vast majority of cases. Suggestions are made for improvements in the current technique.

A case report of a 62-year-old man undergoing general anaesthesia for an inguinal herniorrhaphy is presented. Hypertension bronchospasm, tachycardia, and pulmonary oedema developed during the procedure and the patient was treated for left ventricular failure. Death occured 40 fy&urs ptistoperatively and a phaeochromocytoma on the right side was discovered at post-mortem examination. An account of the causes and significance of hypertension dur,i:ig anaesthesia is given: and a plan of treatment suggested for these cases in which the reason: for the pressor response is difficult to determine. This involves the assessment of ventilation and depth of anaesthesia, use of chlorpromazine and phentolamine. Attention is drawn to the possible need for additional cardiovascular supportive therapy.

Si eanesthesiste, pai ailleurs bien qualifie, ne fait pas ľeffort de quitter sa confortable salle ďoperation pour penetrer dans le bureau du dentiste, ce champ ďaction demeure ouvert ou au medecin peu prepare, ou au dentiste qui peut etre tente de pratiquer simultanement la chiruigie et ľanesthesie. Nous ne pouvons permettre cela. Dans ľune ou ľautre eventualite, le malade est mal servi, et ľanesthesie recule au lieu ďavancei.

Adequate pulmonary ventilation can be obtained in completely relaxed patients under intravenous general anaesthesia by applying the injector principle directly to the human trachea. A jet of oxygen is introduced into the traches by a transtracheal approach, using a 14- or 16-gauge plastic intravenous cannula or by the nasotracheal route, employing a long polyethylene tube corresponding to a 15-gauge intravenous cannula. The latter technique is preferred for routine procedures. Intermittent interruption of jet flow with a Bird Mark II ventilator provides intermittent positive pressure ventilation. The theoretical basis for this technique is outlined and anaesthetic procedure is described. For microscopic endolaryngeal surgery, this approach provides excellent conditions, imposing no restrictions on the operative field or on the duration of surgery.

Different dose ranges of diazepam have been studied in women as to their suitability or otherwise for the purpose of induction of general anaesthesia, and they have been compared with thiopental under standardized conditions. On the basis of our findings it would appear that diazepam is indeed a satisfactory induction agent and because of the minimal effects which it exerts on circulation might be recommended in patients in whom it is advisable to avoid the circulatory depression and tachycardia which so often follows the injection of thiopental, or in those who in the past have demonstrated sensitivity to or intolerance of barbiturates. The state produced by diazepam cannot be compared with thiopental narcosis in that it comes on somewhat more gradually and induces a state of quiescence, unresponsiveness, and amnesia in which the subsequent inhalation agents are accepted readily. Indeed this state of stupor is frequently preceded by a feeling of elation, and general well-being, and by slurring of speech and loquaciousness; these are not seen with thiopental. The only major complication attributable to diazepam itself was the high incidence of burning on injection and of venous thrombosis which followed injection of the drug into the smaller peripheral veins of the upper extremity. However, this complication can be prevented entirely by selecting larger veins such as those in the antecubital fossa.

Energy metabolism and electrolyte values were studied in 28 volunteers during general anaesthesia without operation for periods up to 3 hours. Anaesthesia was induced and maintained with a combination of thiopentone sodium, meperidine, and succinylcholine given by intravenous injection. Ventilation was controlled and normal arterial oxygen and carbon dioxide tensions were maintained. Plasma sodium and potassium concentrations did not change but those of magnesium and inorganic phosphate decreased during anaesthesia. Plasma concentrations of total and ionized calcium, parathyroid hormone, and total protein concentration were unchanged. Blood glucose and plasma insulin concentrations increased from exogenous dextrose but those of fatty acids, ketone bodies, luteinizing hormone, and growth hormone showed no change. General anaesthesia with these nonvolatile agents produced no evidence of a stress response as reflected in energy metabolism.

Plasma catecholamine levels were studied during general anaesthesia with diethyl ether, cyclopropane, and halothane in dogs and human subjects. Anaesthesia with ether/oxygen caused highly significant increases in plasma noradrenaline in dogs and man. The response was less marked in man, but a significant direct correlation could be established (in a small number of patients) between the rise in plasma noradrenaline and blood ether concentrations during ether anaesthesia without surgical interference. Plasma adrenaline was also significantly increased in dogs during ether anaesthesia, and in man to a lesser extent; highly significant rises were measured during surgery in man. The severe metabolic acidosis induced by diethyl ether in the dog bore a direct relationship to circulating catecholamine concentration and was greatly reduced by bilateral adrenalectomy. A mild but definite metabolic acidosis was measured during nitrous oxide/ oxygen/ether and ether/oxygen anaesthesia in man. In adrenalectomized dogs, variable moderate rises in plasma noradrenaline were measured during ether anaesthesia, from which it is inferred that in this species the rise in plasma noradrenaline stems partly from extra-adrenal areas. Since hypercarbia superimposed on ether anaesthesia in adrenalectomized dogs caused further increases in plasma noradrenaline, it is considered that the extra-adrenal sympathetic excitation induced by ether is submaximal.

A method of performing laryngoscopies and bronchoscopies with thiopentone, succinylcholme and a cuirass respirator is described. Our experiences with two hundred cases are summarized Some advantages and disadvantages of the technique are outlined.

1. We have presented a technique of general anaesthesia for eye surgery which is safe and preasant for the patient and is satisfactory to the surgeon and anaesthetist. 2. Pentothal, a relaxant, and cyclopropane and nitious oxide per endotracheal tube are considered a superior anaesthetic routine for any eye surgery. 3. Patients who have received general anaesthesia show no apprehension when they return for a second operation as is evident when this is to be done under local anaesthesia.

An outline is given of the clinical course and pathological processes involved in severe burns in children. The anaesthetist can and should help at every stage. He should advise and help with resuscitation, in the care of the airway and oxygen therapy, in the use of drugs for pain relief, for sedation and for the control of vomiting and anorexia. He should know the place of hypnosis in treating burned children. Case histories are presented from a seven-year review of deaths occurring in burned children at The Children’ s Hospital, Winnipeg. The extent and severity of the pathological changes in burned children can be easily underestimated. The problems of general anaesthesia are described, especially the high incidence of cardiac arrest reported in children with burns of long duration. A review of the literature on this aspect of the problem, together with personal experience, leads to some suggested precautions. These include the pre-operative estimation of blood volume, if feasible, radiography of the chest, and electro-cardiography. During induction of anaesthesia succinylcholine is better avoided and thiopental given slowly and in small doses. Extreme care and gentleness are necessary to assure the safety of such children.