Showing papers in "Canadian Journal of Anaesthesia-journal Canadien D Anesthesie in 1979"

Fentanyl-oxygen anaesthesia for coronary artery surgery: cardiovascular and antidiuretic hormone responses.

Abstract: This study demonstrates that large doses of fentanyl, as the sole anaesthetic with ventilation with oxygen, produces complete anaesthesia and minimal changes in cardiovasuclar dynamics in patients with coronary artery disease. It also indicates that high dose fentanyl anaesthesia blocks the increase in plasma anti-diuretic hormone and cardiovascular dynamics which are so common with morphine and other anaesthetic techniques during tracheal intubation and surgical stimulation in patients with coronary artery disease. Our findings suggest that fentanyl-oxygen anaesthesia is an attractive technique in patients with coronary artery disease.

Human misadventure in anaesthesia.

Abstract: An account is given of the 602 anaesthetic accidents reported to the Medical Defence Union of the United Kingdom over the eight-year period 1970-1977: these were reported from a total membership of 2,000 anaesthetists. It is known that reporting of minor accidents, for example damage to teeth, is very imcomplete, and that many deaths associated with surgery but due to disease processes rather than anaesthesia would not be reported either. It is thought, however, that the reporting by members of other accidents involving death and cerebral damage is likely to be complete, or nearly so. Cases of death and cerebral damage reported numbered 348 (60 per cent of the total) and the causes of these two major accidents were so closely similar that it was possible to deal with them together. This appears to be a suitable approach since cerebral damage can be as great, or greater, a catastrophe than death. In nearly half of this group of accidents there was discernibly faulty technique. Failure of postoperative care ( 10 per cent of the 348 cases) was another prominent and avoidable cause. Analysis of the faulty anaesthetic techniques which led to these major accidents showed that factors involved in tracheal intubation were preeminent, and that misuse of apparatus was also conspicuous. Over all error was deemed to be twice as common a cause of death and cerebral damage as was misadventure.

Efficacy of helium--oxygen mixtures in the management of severe viral and post-intubation croup.

Abstract: An appreciable number of children with viral or post-intubation croup progress to respiratory failure necessitating an artificial airway. We report seven such patients with critical airway narrowing in whom we reduced the work of breathing by developing helium rather than air as a carrier gas for oxygen. Assessment of patients by a croup-scoring system and blood gas analysis suggests helium-oxygen mixtures to be a useful alternative to intervention with tracheostomy or tracheal intubation. The rationale and limitations of this treatment are discussed.

Midazolam maleate induction in patients with ischaemic heart disease: haemodynamic observations

Abstract: Midazolam maleate is a new water soluble benzodiazepine used for induction of anaesthesia. Ten patients with symptomatic ischaemic heart disease were premedicated intramuscularly with morphine 0.l mg · kg-1 and scopolamine 6–8 µg · kg-1, 60–90 minutes before induction. The heart rate, systolic/diastolic blood pressure, mean systolic blood pressure, mean pulmonary artery blood pressure, pulmonary artery occluded pressure, mean right atrial pressure, cardiac output (duplicate thermodilution) and arterial blood gas tensions were measured at four time periods: (1) after instrumentation while breathing room air, (2) after transfer to the operating room while breathing 100 percent oxygen by mask, (3) one to two minutes after intravenous midazolam maleate 0.2 mg · kg-1 and (4) four to five minutes after midazolam maleate. The cardiac index, stroke index, heart ratesystolic blood pressure product, systemic vascular resistance index, pulmonary vascular resistance index, left ventricular stroke work index and right ventricular stroke work index were calculated for each of the study time-periods from the measured parameters.

Pulmonary atelectasis and other respiratory complications after cardiopulmonary bypass and investigation of aetiological factors

Abstract: Radiological evidence of pulmonary complications and possible aetiological factors were investigated in 50 consecutive patients after heart operations with cardiopulmonary bypass. Atelectasis was the most frequent pulmonary complication except for small pleural effusions, with an incidence of 64 per cent. Several types of atelectasis frequently co-existed, with a predominance of the less extensive plate and subsegmental forms. The incidence of atelectasis was the same on each side and the site of atelectasis was basal in three quarters of the patients. Preoperative clinical and catheter data were unrelated to the incidence of atelectasis. There was a significant positive correlation between a short cardiopulmonary bypass time and plate atelectasis, between a large fluid load after bypass and segmental atelectasis, between re-operation for bleeding and subsegmental atelectasis and between post-operative gastric dilation and atelectasis. The type of operation, the use of the intra-aortic balloon and the length of postoperative respiratory ventilation were unrelated to the incidence of atelectasis. The mechanism of development of atelectasis is discussed.

Ventilation and chemoreflexes during enflurane sedation and anaesthesia in man

Abstract: Enflurane sedation and anaesthesia in healthy fit subjects reduced ventilation and the response to carbon dioxide, hypoxaemia and a low dose of doxapram, all in a dose-related fashion. Comparing the three chemoreflexes tested, the response to hypoxaemia and doxapram were the more profoundly impaired; they were nearly totally abolished by anaesthesia. These effects of enflurane on chemoreflex activities are qualitatively similar to those previously observed with halothane.

Prophylactic blood patch does not prevent post lumbar puncture headache

Abstract: Of 86 patients in whom accidental puncture of the dura occurred during insertion of a needle for induction of epidural analgeisa for labour and delivery, 11 received a prophylactic blood patch at the completion of delivery. Of the 75 patients with no prophylactic blood patch, 59 per cent developed post-lumbar-puncture headache, while 54 per cent of those who had a prophylactic blood patch developed headache. The prophylactic blood patch appears to have no value in preventing post-lumbar-puncture headache in this small group of patients.

Comparison of droperidol, haloperidol and prochlorperazine as postoperative anti-emetics.

Abstract: The results of this study demonstrate that prochlorperazine, haloperidol and droperidol are all effective post-operative anti-emetic compounds when compared to saline but vary in onset of activity and duration of action. Haloperidol has the shortest onset of action, being effective within 30-minutes of intravenous administration. Prochlorperazine has an intermediate onset of action and droperidol is the slowest of the three compounds but the only one to provide significant anti-emesis 4–24 hours following administration. Our data suggest that a combination of haloperidol and droperidol may be more effective as an anti-emetic than any one of the compounds used alone.

Midazolam compared with thiopentone as a hypnotic component in balanced anaesthesia: a randomized, double-blind study.

Abstract: Midazolam is a short-acting water soluble benzodiazepine derivative. It is a hypnotic used for intravenous anaesthesia induction. The present investigation was designed in a prospective double-blind fashion to compare midazolam with thiopentone as hypnotic components in balanced anaesthesia. The study included 50 healthy patients undergoing relatively short surgical procedures. The results revealed that thiopentone is faster in onset than midazolam for induction of anaesthesia, with less variation of dose response. However, maintenance of anaesthesia was superior with midazolam, requiring fewer supplemental anaesthetic drugs, having better patient acceptance and providing more amnesia. Postoperative complications were very low with both techniques. Midazolam was surprisingly similar to thiopentone in most parameters including emergence time from anaesthesia. Midazolam is a new drug with potential both for induction of anaesthesia and maintenance of balanced anaesthesia.

The regulation of $$Pa_{CO_2 } $$ during controlled ventilation of children with a T-piece

Abstract: A lung model study described the factors determining the carbon dioxide tension during controlled ventilation with a T-piece system (either a Bain circuit or the classical Ayre’s T-piece). When minute ventilation was large with respect to fresh gas flow and a standard ventilatory pattern was utilized the important variables were fresh gas flow (FGF) and carbon dioxide production $$\left( {\dot V_{CO_2 } } \right)$$ . Under these circumstances the influence of minute ventilation $$\left( {\dot V_E } \right)$$ , dead space to tidal volume ratio (VD/VT), waveform and $$a - AD_{CO_2 } $$ on carbon dioxide tension were minimized. Eight healthy patients (11–64 kg) were studied during controlled ventilation to determine how much of the fresh gas coming from the flowmeters actually participates in gas exchange. With a T-piece system when minute ventilation to fresh gas flow ratio is at least 1.5 the patient’s effective alveolar ventilation equals 72 per cent of the total fresh gas flow. This value and levels of carbon dioxide production from the literature were used to derive a simple two part formula of fresh gas flow requirements for two levels of arterial carbon dioxide in children. Children weighing between 10 and 30 kg require fresh gas flows of 1000 + 100 ml · kg-1 · min-1 and 1600 + 100 ml · kg-1 · min-1 to achieve arterial carbon dioxide tensions of 4.9 kPa (37 torr) and 4.0 kPa (30 torr) respectively. When body weight is between 30 and 70 kg the requirements increased to 2000 + 50 ml · kg-1 · min−1 to achieve a $$Pa_{CO_2 } $$ of 4.9 kPa (37 torr) and 3200 + 50 ml · kg-1 · min-1 to achieve a $$Pa_{CO_2 } $$ of 4.0 kPa (30 torr). In all situations Ve must be at least twice the fresh gas flow requirements. p ]The formula was validated in a heterogeneous group of 26 patients. Mean values of $$Pa_{CO_2 } $$ were very close to those predicted, although individual values differed considerably from the mean. These deviations cannot be eliminated because of patient and equipment variability. Therefore blood gas analysis must be performed whenever the exact regulation of $$Pa_{CO_2 } $$ is required.

The cardiovascular effects of ketamine used for induction of anaesthesia in patients with valvular heart disease

Abstract: The effects of induction of anaesthesia by ketamine 2 mg.kg-1 were studied in six patients with valvular heart disease before tracheal intubation and operation. Cardiac index was unaffected because a mean decrease in stroke index was compensated for a mean increase in heart rate. A significant increase was found in mean arterial pressure, pulmonary arterial mean pressure, pulmonary capillary wedge pressure and central venous pressure. Systemic vascular resistance increased, but not significantly, whereas pulmonary vascular resistance increased significantly by more than 150 per cent. Right ventricular minute work index increased in all patients, and the increase was as much as 400 per cent. Left ventricular minute work index increased in four of the six patients, but the magnitude of the increase was not so marked. It is therefore concluded that ketamine causes pronounced pulmonary vasoconstriction and an undesirable strain on the myocardium. Such effects could prove deleterious in patients with limited functional reserve of the right ventricle.

Knotting of an epidural catheter: a case report.

Abstract: Difficulty with removal of an epidural catheter is described due to formation of a knot near the end of the catheter. It is stressed that in the lumbar area an epidural catheter should never be inserted more than 5 cm into the epidural space, as curling with knot formation may occur. Removal may be attempted by pulling on the catheter if testing of a similar catheter indicates that it will withstand the tension. The patient and the spouse should be kept informed and involved in the decision-making for medico-legal reasons.

Awareness, muscle relaxants and balanced anaesthesia.

Abstract: The incidence of awareness during insufficient anaesthesia is reported to be one per cent. It is usually due to the use of muscle relaxants, a balanced technique and the lightest possible depth of anaesthesia. Increased incidences were noted in open-heart surgery, during intubation-endoscopy procedures and in caesarean delivery patients. Experiences of awareness are disturbing to patients, who are usually benefited by a sympathetic and forthright explanation of the event. Fourteen representative cases of the problem are reported. Since no adequate sign or test exists for detection of awareness during very light anaesthesia or with associated paralysis, more meticulous attention is required in using relaxants or the balanced technique. Greater anaesthetic supplementation and reduction in the use of relaxants are recommended to halt the recurrence of this most serious anaesthetic problem.

Intubation and other experiences in cardiac surgery: the consumer’s views

Abstract: Recent publications have advocated earlier weaning and early extubation of the trachea in patients after cardiac surgery. Greater comfort of the patients is one of the advantages claimed for this policy. One hundred consecutive adult patients were questioned on the fifth postoperative day to assess the relative comfort or discomfort of the patients during tracheal intubation and ventilation. Overnight tracheal intubation and ventilation were easily tolerated by over 90 per cent of patients who had received morphine and diazepam. There was a high incidence of amnesia. Some of the other claimed advantages appear inconclusive and further study is desirable to elucidate the effect of early removal of the tracheal tube upon the indicence of pulmonary complications.

Rectal methohexitone for induction of anaesthesia in children.

Abstract: Rectal induction of anaesthesia using ten per cent methohexitone is a safe and effective method for young children. It is particularly applicable to the child three months to four years of age. Twenty-five mg- kg-1 of methohexitone should be given and the child should be observed continuously by the anaesthetist until he falls asleep. Equipment to establish an artificial airway and to ventilate the lungs should be immediately at hand. The use of rectal methohexitone does not significantly delay immediate or late recovery after short (30-minute) surgical procedures.

Preservation of auditory-evoked brainstem responses in anaesthetized children.

Abstract: In a series of six anaesthetized children we have been unable to demonstrate any effect of anaesthetic concentrations of halothane or thiopentone on the brainstem auditory-evoked response. The results imply preservation of brain stem function during anaesthesia with these drugs and suggest future application of anaesthesia to the testing of hearing disabilities in children, as well as application of evoked response audiometry to neurological critical care.

Chronic pain syndromes and their treatment. III. The piriformis syndrome.

Abstract: The piriformis is a deep-seated muscle, most of its muscular portion being part of the dorsal wall of the pelvis. The lateral portion and its insertion is extra-pelvic and lies deep to the glutei. Like more superficially located and therefore more easily accessible skeletal muscles, the piriformis too can be the seat of trigger points, giving rise to symptoms indistinguishable from those of other causes of low backache, unless a deliberate search is made for the signs specific to the piriformis syndrome. Having made a presumptive diagnosis, confirmation is. gained by palpating the muscle itself via rectum or vagina and reproducing the pain by digital pressure. If this test also is positive, the muscle is injected, the approach being either through the sciatic notch, from the perineum, or through the vagina. Immediate relief of pain is experienced after the solution of local anaesthetic and steroid has been deposited deep within the fleshy portion of the muscle.

Anaesthetic considerations in the prolonged Q-T interval (LQTS): A case report

Abstract: A case of prolonged Q-T interval syndrome (LQTS) with ventricular dysrhythmias is presented. The patient was unresponsive to medical treatment. Left stellate ganglion block, followed be surgical excision of the ganglion, resulted in reversion to normal sinus rhythm. The causes of LQTS, its treatment and the effects of anaesthetic agents are discussed.

Acute airway obstruction: a complication of aluminum tape wrapping of tracheal tubes in laser surgery

Abstract: A case is reported of acute airway obstruction arising from the use of a tracheal tube wrapped with aluminum tape during laryngeal surgery with a carbon dioxide laser. Problems associated with aluminum tape wrapping of tracheal tubes are discussed.

Ventricular fibrillation in a patient with unsuspected mitral valve prolapse and a prolonged Q-T interval.

Abstract: Mitral valve prolapse is a common cardiac abnormality associated with arrhythmias and sudden death. In most instances it can be diagnosed on the basis of physical findings. Those patients who are symptomatic or who display electrocardiographic abnormalities appear to be most susceptible to arrhythmias and, therefore, may be at increased risk for anaesthesia. Because the syndrome is relatively common and may present a very innocent clinical picture, anaesthetists should be aware of this condition and the problems it may present. A case of mitral valve prolapse syndrome associated with ventricular fibrillation on induction of anaesthesia is reported. The symptoms and pathophysiology of the disorder are reviewed and the potential problems and the anaesthetic management are discussed.

Epidural analgesia and the metabolic response to surgery.

Abstract: The effect of epidural blockade on the metabolic and hormonal responses to pelvic surgery was investigated in 14 female patients Central venous blood samples were collected every 30 minutes and analysed for free fatty acids, glycerol, β-hydroxybutyrate, acetoacetate, glucose, lactate, pyruvate, cortisol and growth hormone concentrations There was no change in fat and glucose metabolism except for a transient decrease in lipolysis after 30 minutes of surgery Cortisol and growth hormone values were significantly increased (p < 001) after 60 minutes A small but statistically significant increase in blood lactate concentration was observed (p< 001) and the concept of a “metabolic V/Q” abnormality is postulated to explain the lacticacidaemia

Chronic pain syndromes and their treatment. II. Trigger points.

Abstract: Trigger points are distinct areas of focal hyperirritability which give rise to areas of referred pain in well-defined areas of the musculoskeletal system, sometimes remote from the point itself and not related to it by anatomically definable pathways. While the vast majority of pain manifestations from trigger points are related to the musculo-skeletal system, this need not be invariably so, as has been demonstrated in two of the cases cited, where injection of trigger points in the neck relieved chronic tinnitus. In all manifestations of chronic pain it is recommended that a diligent search be made for such trigger points.

The humidification of anaesthetic gases: its importance and control.

Abstract: Les auteurs ont decrit les differentes definitions concernant ľhumidite des gaz ďanesthesie et ont etudie les facteurs capables ďinfluencer sa regulation. Ils ont de plus demontre les effets nefastes de ľemploi des gaz secs qui dessechent les muqueuses respiratoires et elevent le pourcentage des complications pulmonaires qui suivent ľanesthesie. Une revue du debit de vapeur ďeau des systemes en usage courant a ete suivie par une description des mesures prises pour elever ľhumidite des gaz respires par les malades durant ľanesthesie. Ils ont aussi recommande la reduction de ľhumidite durant les periodes ďhyperthermie et les precautions a prendre pour eviter la contamination microbienne des equipements ďanesthesie, un risque augmente durant ľhydratation des gaz aspires par les malades.

A randomized evaluation of the reversal of ketamine by physostigmine.

Abstract: One hundred and eleven patients undergoing ketamine anaesthesia for therapeutic abortion were studied in a double-blind trial of the reversal of ketamine by physostigmine administered postoperatively. The results demonstrate that physostigmine does not shorten recovery time or reduce the occurrence of ketamine emergence phenomena such as hallucinations, restlessness and dreams. In fact, the recovery course was prolonged in patients given physostigmine immediately upon termination of anaesthesia as compared with controls. By contrast, when physostigmine was given 30 minutes after the last dose of ketamine, the recovery was not prolonged as compared with that of the placebo-treated controls. These findings suggest some synergism between the effects of ketamine and physostigmine and should discourage the use of physostigmine as a ketamine antidote.

Successful use of dantrolene sodium in human malignant hyperthermia syndrome: a case report

Abstract: We present a case of malignant hyperthermia in which successful management included the intravenous use of dantrolene sodium. A subsequent operation under spinal anaesthesia with oral dantrolene prophylaxis did not lead to development of malignant hyperthermia. Since this syndrome is rare during regional anaesthesia, the role of prophylactic oral dantrolene in preventing the redevelopment of malignant hyperthermia in our patient is open to question.

Pancuronium for rapid induction technique for tracheal intubation.

Abstract: Suxamethonium in a dose of 2 mg · kg-1 was compared to pancuronium in three different dosages (0.1 mg · kg-1, 0.15 mg · kg-1, 0.2 mg · kg1) for a rapid induction (crash) technique for tracheal intubation. Pancuronium 0.1 mg · kg-1 was inferior to suxamethonium, but the larger doses of pancuronium were equally satisfactory. In those instances where suxamethonium is either contraindicated or undesirable, pancuronium in a dose of 0.15 mg · kg-1 is a suitable alternative for rapid induction for tracheal intubation.

Anaesthesia and the respiratory system.

Abstract: Pulmonary gas exchange is disturbed during general anaesthesia; both oxygenation and elimination of carbon dioxide are impaired. The shape of the chest wall alters after induction of anaesthesia-paralysis in recumbent subjects, and its motion during inspiration is also altered. The mechanical properties of lung and chest wall are also affected and FRC may be reduced. Inspired gas distribution changes after induction of anaesthesia-paralysis with mechanical ventilation of the lungs. Distribution of pulmonary blood flow is altered in subjects in the sitting and right lateral decubitus positions, but the distribution is not adjusted to the altered distribution of inspired gas. This results in an increased mismatching of ventilation to perfusion, with development of lung regions that have low and high ventilation-to-perfusion ratios. Some lung regions with low ventilation-to-perfusion ratios develop into right-to-left shunt on breathing 100 per cent oxygen. The following sequence of events probably occurs after induction of anaesthesia-paralysis. The initial effect of anaesthesia seems to be on the shape and motion of the chest wall. This may alter the mechanical properties of both the chest wall and the lung. Intrapulmonary gas distribution is altered secondarily. Pulmonary bloodflow distribution, which is primarily determined by gravity, does not seem to adjust to the altered distribution of inspired gas. Hence, an increased mismatching of ventilation to perfusion develops. This includes the development of lung regions with low ventilation-to-perfusion ratios. These regions may progress into right-to-left shung during 100 per cent oxygen breathing. The low ventilation-to-perfusion regions and the shunt may both impair oxygenation. The development of lung regions with high ventilation-to-perfusion ratios after induction of anaesthesia-paralysis contributes to the inefficient elimination of carbon dioxide.

Posterior laryngeal cleft - anaesthetic experiences.

Abstract: Two cases of congenital posterior laryngeal cleft are reported which typify the anaesthetic techniques used for operation on this defect at The Hospital for Sick Children, Toronto. Although this anomaly of the airway is rare, it is potentially curable by surgery and should be included in the differential diagnosis of neonatal respiratory distress aggravated by feeding. The anaesthetic technique used for microlaryngeal surgery consisted of topical lidocaine, insufflation of oxygen and halothane with supplementary methoxyflurane and spontaneous ventilation. A nasotracheal tube is left in situ postoperatively until laryngeal oedema has subsided. The literature is reviewed and the relevant anaesthetic experience over a ten-year period at The Hospital for Sick Children, Toronto, is summarized.

Bacterial filters — are they necessary on anaesthetic machines?

Abstract: At the Vancouver General Hospital the effectiveness of the system for decontamination of anaesthetic equipment was evaluated to determine the need for bacterial filters on anaesthetic machines.

Phaeochromocytoma and postoperative hypoglycaemia.

Abstract: A case of hypoglycaemia following the removal of a phaeochromocytoma is reported and the mechanisms that influence the blood sugar before and after the removal of that tumour are discussed.