Showing papers in "Canadian Journal of Anaesthesia-journal Canadien D Anesthesie in 1975"

A simplified scoring system for the post-operative recovery room.

Abstract: A new and very simple scoring system for recording post-anaesthetic recovery is described. When numerical values are assigned to factors indicating recovery progress or lack of it is obvious. The records may have medico-legal value. It can be incorporated into the Recovery Room Record.

A Sudden death associated with the use of sodium nitroprusside for induction of hypotension during anaesthesia

Abstract: A death from cyanide poisoning during operation was attributable to the use of approximately 400 mg (10 mg per Kg) sodium nitroprusside as an hypotensive agent. Autopsy cyanide levels of 0.5 mg per cent in blood and 0.3 mg per cent in urine and thiocyanate levels too low to measure in either, suggest an abnormality of cyanide metabolism. The lethal dose of sodium nitroprusside appears to be 7 mg per Kg. A safe regimen would be 3.5 mg per Kg as the anticipated total dose for the period of hypotension. Patients resistant to the full hypotensive effects of sodium nitroprusside, or unable to maintain the level of hypotension, or requiring more than 3.5 mg per Kg to achieve the required effect for the anticipated time, may accumulate toxic levels of cyanide in the blood. Patients with Leber’s optic atrophy, tobacco amblyopia and possibly those with other nerve atrophies should not receive sodium nitroprusside or any other cyanide precursor.

Percutaneous transtracheal ventilation for anaesthesia and resuscitation: a review and report of complications.

Abstract: Percutaneous transtracheal ventilation with intermittent jets of oxygen under high pressure has been used for approximately five years. This paper briefly reviews published reports on the use of this technique for resuscitation and during anaesthesia. Complications occurring in the reports reviewed are tabulated. The complications occurring in a series of 80 patients (52 elective prior to anaesthesia and 28 for acute respiratory distress) at the Pittsburgh Eye and Ear Hospital are documented. This includes three detailed case reports. No deaths and few serious complications have so far been reported, particularly with the elective use of transtracheal ventilation. This technique has established itself as an important adjunct in life support. When used in properly selected cases, its continued use appears justified.

Post-operative epidural analgesia: effects on lung volumes.

Abstract: A study was undertaken to assess the role of post-operative pain in reducing Functional Residual Capacity (FRC) and Vital Capacity (VC). The efficacy of post-operative epidural analgesia in reversing these changes was measured in eight subjects after upper abdominal operations. With pain, FRC and VC were 78 per cent and 37 per cent of control respectively. Following epidural analgesia, the values were 84 per cent and 55 per cent. These figures indicate the pain component in the post-operative reduction of these two lung capacities. This partial restoration may be of value in the prevention of post-operative pulmonary complications by avoiding closure of small airways during tidal breathing and by increasing the effectiveness of deep breathing and coughing in the removal of secretions and the reversal of atelectasis.

The cerebral response to sodium nitroprusside and trimethaphan controlled hypotension.

Abstract: Cette etude avait pour but d’etablir la marge de securite associee a l’emploi d’hypotension controllee en neuro-chirurgie, hypotension produite soit avec du Trimethaphan ou du Nitro-prussiate. Ces agents par leur action sur la resistance vasculaire permettent de diminuer la pression de perfusion cerebrale (C.P.P.) tout en maintenant le flot sanguin cerebral (C.B.F.) et le mecanisme d’autoregulation. L’etude a porte sur deux groupes de sept chiens chacun. Les chiens du permier groupe ont recu du Trimethaphan, ceux du second du Nitroprussiate. On a etudie les parametres suivants: flot sanguin cerebral (CBF), consommation d’O2 cerebrale (CMRO2), resistance vasculaire cerebrale (CVR) et debit cardiaque. On a observe que pour une diminution du meme ordre du flot sanguin cerebral, avec pression de perfusion superieure a 60 mm Hg, il y a conservation de l’autoregulation; au-dessous de 60 mm Hg de pression de perfusion il y a perte du mecanisme d’autoregulation avec le Trimethaphan et conservation de ce mecanisme avec le Nitroprussiate, meme a des pressions de perfusion basses, le debit sanguin cerebral se maintient stable, grâce a une vasodilatation (chute de la resistance vasculaire cerebrale parallele a la chute de la pression de perfusion. Ce mecanisme permet une extraction adequate d’oxygene au niveau cerebral. Par ailleurs, avec le Trimethaphan aux memes basses pressions de perfusion, on observe une diminution de l’extraction cerebrale d’O2 traduisant une hypoxie; contrairement a ce qu’on observe avec le Nitroprussiate, il y a maintien de la resistance vasculaire cerebrale, le flot sanguin cerebral devenant ainsi dependant de pression de perfusion. La diminution initiale de debit cardiaque observee avec les deux agents devient plus prononcee a mesure qu’on augmente les doses de Trimethaphan, phenomene qui n’est pas observe avec le Nitroprussiate.

A method for prevention of cardiovascular reactions to laryngoscopy and intubation.

Abstract: A technique of nebulizing lidocaine in the upper airways was developed and its effectiveness in preventing cardiovascular responses to laryngoscopy and intubation was documented. In ten pre-treated patients the average percentage-rise in systolic blood pressure was 10.3 per cent and there were no arrhythmias. The pulse rate increased by 16.8 per cent. In ten control patients, the systolic blood pressure increased by 56 per cent and the incidence of arrhythmias was 40 per cent. The pulse rate increased by 38.8 per cent. The significance and application of these results is discussed and compared to other available methods. The opinion is expressed that the effect of the aerosol, especially as it relates to the suppression of arrhythmias, is partly due to systemic absorption of lidocaine.

Sodium nitroprusside in children: Observations on metabolism during normal and abnormal responses

Abstract: Three different responses to sodium nitroprusside as a hypotensive agent during anaesthesia in children are described. A constant high dose (greater than 3 mg/Kg) response to, abnormal resistance to and tachyphylaxis to the drug are recognised and are dangerous and potentially lethal. They are probably related to abnormalities of cyanide-thiocyanate metabolism resulting in cyanide accumulation. The abnormal responses produce metabolic acidosis, an increase in mixed venous oxygen tension and a decrease in arterial mixed venous oxygen content difference. Tachyphylaxis may be due to depletion of endogenous thiosulphate and was reversible by sodium thiosulphate therapy (150 mgm/Kg) in two cases in which it was used.

Response to hypercapnia under ketamine anaesthesia

Abstract: The respiratory response to hypercapnia in dogs anaesthetized with ketamine was increased. This respiratory stimulation was most probably due to a direct effect of the drug on the medullary respiratory neurones. This effect was not modified by preanaesthetic medication pentobarbitone 5 mg/kg or morphine 0.1 mg/kg. Catecholamine response to hypercapnia was essentially the same as that reported by hypercapnic dogs anaesthetized with thiopentone.

Anaesthesia for dwarfs and other patients of pathological small stature.

Abstract: Sixty-nine anaesthetics were administered to 29 patients of pathological proportionate and disproportionate small stature. The anaesthetic course in most cases was uncomplicated. The few complications noted were similar in type and severity to those found in normal size patients undergoing similar anaesthesia and operative procedures. Achondroplastic dwarfs often develop neurological problems due to their bony deformities. General anaesthesia should be given preferential consideration in these patients. Non-achondroplastic dwarfs may have an associated odontoid dysplasia and if the neck is placed in flexion there is a potential risk of spinal cord damage. Tube size for proportionately small children is best estimated from body weight. No definite recommendations concerning proper tube size in dwarfs can be given on the basis of the findings in this study.

Prediction of arterial carbon dioxide tension during controlled ventilation with a modified Mapleson D system.

Abstract: Based on measurements of arterial CO2 tension in 132 adult patients, a curve was constructed relating fresh gas inflow and arterial CO2 tension for a modified Mapleson D system. In patients on controlled ventilation using a ventilating volume greater than the predicted respiratory minute volume, it was found that the arterial Pco2 can be predicted from the fresh gas inflow with an accuracy sufficient to be clinically useful.

Airway closure in pregnancy.

Abstract: Closing capacity (CC; the lung volume at which dependent lung zones cease to ventilate, presumably as a result of airway closure) and standard lung volumes were measured in twenty-four normal women 21 to 29 years of age in the seated and supine positions. Measurements were made serially during pregnancy and once 6 to 8 weeks post partum (the control period). CC was unchanged during pregnancy, while functional residual capacity (FRC) fell by approximately 15 per cent. The difference between FRC and CC (FRC-CC) was reduced during pregnancy, but in one of the subjects when seated, and in only two supine subjects did CC exceed FRC. FRC-CC was reduced in the supine position as compared to seated. The reduced FRC-CC during pregnancy offers a potential explanation for the observations of abnormally low arterial oxygen tensions (Pa02) during pregnancy in some women, and of reduced Pa02. in pregnant women in the supine as compared to upright position.

A consideration of ketamine dreams.

Abstract: This study was designed to see whether covering of the eyes during and after ketamine anaesthesia would reduce the incidence of dreams. One hundred and fifty patients, randomly divided into three groups, underwent therapeutic abortion with ketamine as the sole anaesthesia. One hundred patients had their eyes completely covered, 50 in the operating room only and 50 in the operating room and in the recovery room. The third 50 were controls, with their eyes uncovered. All patients were questioned post-operatively about dreams, nausea and vomiting, headache, dizziness and other experiences, and also how frequently they dreamed at home. Although covering the eyes in the recovery room only reduced the incidence of dreams marginally, it became obvious that the patients who dreamed after ketamine (in all 3 groups) were those who normally dreamed at home. There were 82 patients who were recorded as not being home-dreamers, and only two of these dreamed after ketamine. In contrast, of the 68 home-dreamers, 50 dreamed after ketamine, and 17 of these had unpleasant dreams. In the home-dreamers, covering the eyes reduced the incidence of dreams from 86 per cent in Group 1 to 72 per cent in Group 2 and 64 per cent in Group 3. It is suggested that goggles may be advantageous when dealing with home-dreamers, and a question about the patient’s tendency to dream should be included in the preoperative questioning. Alterations in premedication and the use of a quiet dark room during recovery may even further reduce unpleasant dreams in this group.

Pathogenesis of gangrene following intra-arterial injection of drugs: a new hypothesis.

Abstract: We have demonstrated the toxicity of diazepam and the safety of ketamine hydrochloride following intra-arterial injection in an anaesthetized animal model.

Anaesthetic complications in surgical out-patients.

Abstract: This study reports retrospectively the post-anaesthetic complications in surgical out-patients. We have studied the incidence and severity of these complications during the first five post-operative days in 500 female patients who underwent tubal ligation by laparoscopy. The report shows that post-anaesthetic complications in surgical out-patients are frequent but of mild severity. Although they produced some discomfort for the patients most of them were of the opinion that the advantages of having the operation as out-patients made up for the discomfort.

Effect of isoflurane anaesthesia and surgery on carbohydrate metabolism and plasma cortisol levels in man.

Abstract: The present study was undertaken to investigate in nine male surgical patients the effects of isoflurane anaesthesia alone on the carbohydrate metabolism by determining plasma growth hormone (GH), insulin, blood glucose, and cortisol, and to compare them with the effects of anaesthesia associated with surgical operations. Determination of plasma GH, insulin, cortisol, and blood glucose were made simultaneously before induction of isoflurane anaesthesia, after maintenance of anaesthesia for 15 minutes and 30 minutes and during and after conclusion of the operation. Plasma GH concentrations showed a significant elevation during isoflurane anaesthesia, and maintained a similar high level one hour after the start of the operation. An insignificant elevation in plasma insulin level and significant increases in blood glucose were noted during anaesthesia and operation. Plasma cortisol levels increased insignificantly during anaesthesia, but increased markedly during operation. Our observations would suggest that the increased blood level of GH and elevated blood cortisol play a part in the increase of blood glucose during isoflurane anaesthesia and surgical operations in man.

Doses of epinephrine causing arrhythmia during enflurane, methoxyflurane and halothane anaesthesia in dogs.

Abstract: The arrhythmogenic dosage of epinephrine, administered by constant intravenous infusion, was measured in five dogs during enflurane, methoxyflurane and halothane anaesthesia. While premature ventricular contractions were observed in only one of five dogs with enflurane and methoxyflurane, epinephrine-induced arrhythmias were seen in all animals during halothane anaesthesia. Epinephrine dosage and the resultant increase in mean arterial blood pressure at which arrhythmias occurred during halothane anaesthesia were significantly less (p < 0.05) than with the other anaesthetics. These observations indicate that enflurane and methoxyflurane, as compared to halothane, possess relatively less arrhythmogenic potential as sensitizing agents in the presence of increased circulating catecholamines.

Glycopyrrolate methobromide 2. Comparison with atropine sulphate in anaesthesia

Abstract: A double blind study of 98 patients was undertaken to compare the clinical usefulness of atropine and glycopyrrolate for pre-anaesthetic medication and their relative effectiveness in antagonizing the muscarinic effects of neostigmine methylsulphate given to reverse neuromuscular blockade. Intramuscular administration of atropine 0.4 mg or of glycopyrrolate 0.2 mg produced the same degree of dryness of the pharynx. However, glycopyrrolate was found to be a more potent antagonizer of the increased salivation induced by neostigmine. By intramuscular administration, both drugs produced the same degree of tachycardia, although atropine tended to cause no change in the pulse rate or even to produce bradycardia in a greater number of patients. Administered intravenously, atropine produced a more significant tachycardia in a large number of patients prior to neostigmine administration, although the protection against a decreased pulse rate from neostigmine is greater in those patients who received glycopyrrolate. It would appear, therefore, that glycopyrrolate is more effective in antagonizing the muscarinic effects of neostigmine methylsulphate.

Ulnar nerve injury associated with anaesthesia

Abstract: Information regarding 35 patients who developed signs and symptoms of lesions in the ulnar nerve during the post-anaesthetic period, has been reported. The pertinent anatomical and physiological factors in the aetiology of compression neuropathy of the ulnar nerve have been summarized. The use of electromyography and nerve conduction studies has been discussed in relation to localizing the site, following the progression, estimating the severity of a lesion and helping to differentiate between a recent or a pre-operative lesion. Lesions of the ulnar nerve continue to occur in patients who receive an anaesthetic. In our cases the severity of the lesions was not related to age, sex, type of operation or anaesthetic or the duration of the anaesthetic. Compression neuropathies of the ulnar nerve occurred more commonly in males than females. They may lead to a prolonged disability. Preventive measures and the importance of adequate follow-up have been discussed briefly.

The cardiovascular effects of ketamine in hypotensive states.

Abstract: Ketamine was found to raise the systemic arterial blood pressure but not necessarily the perfusion in hypovolaemic states. However, in hypotensive states of short duration from endotoxin treatment, it improved the haemodynamics with increase in both the perfusion and the systemic pressure. The implications of these observations for clinical situations were discussed.

Vascular responses to anaesthetic agents

Abstract: Data have been presented showing that certain general anaesthetic agents such as halothane decrease the spontaneous activity of the rabbit anterior mesenteric portal vein and decrease the response of venous and aortic strips to exogenous noradrenaline. If these observations can be extrapolated to the intact animal they may indicate that the hypotension occurring with use of such agents may be due not only to cardiac effects but also to peripheral vasodilatation and muting of reflex sympathetic vasoconstriction. Although the response to noradrenaline is antagonized, this appears to be nonspecific effect and no evidence was found for interference with noradrenaline release nor for direct actions on beta-adrenegic receptors. While the thiobarbiturates increased spontaneous activity and tone of the rabbit anterior portal vein no evidence was obtained that this occurred through release of noradrenaline from tissue stores.

Anaesthesia for intestinal short circuiting in the morbidly obese with reference to the pathophysiology of gross obesity.

Abstract: 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°. 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.

Measurement of intratracheal oxygen concentrations during face mask administration of oxygen: A modification for improved control

Abstract: Direct measurement of the inspired tracheal oxygen concentration was made in patients breathing through standard aerosol face masks Factors affecting the tracheal FIO2 were analyzed using both mechanical and mathematical models When oxygen is delivered to the face mask at low flow rates, there is considerable patient variation in the measured tracheal FIO2 Delivery of oxygen at higher flow rates (15 litres per minute or greater), reduces such variation Furthermore, turbulent air currents within and around the face mask reduce the measured FIO2 and contribute to fluctuations in the FIO2 This effect may be virtually eliminated by placing shields around the mask orifices as described Using the shielded mask, it is possible to deliver the desired oxygen concentration to the patient more accurately and to maintain humidification of the delivered gases Changes desired in inspired oxygen concentration are accomplished by changing the concentration of the incoming gas mixture, and not by merely changing the flow rate of oxygen delivered to the system Using the shielded mask, it is possible to deliver an inspired oxygen concentration of 100 per cent This is not true with most other commonly used face masks, and, therefore, caution should be used to avoid administration of unnecessary high inspired oxygen concentrations with this type of mask

A hazard associated with improper connection of the Bain breathing circuit.

Abstract: A case of cardiac arrest is presented which was caused by improper connection of a modified Mapleson D circuit (Bain breathing circuit). Excessive external deadspace was created by interchanging the gas inflow line and the attachment for an airway pressure manometer. This resulted in a marked respiratory acidosis, clinically undetected until the concomitant hypoxia produced a severe cardiac depression and arrest. The sequence of events was reproduced in a dog under comparable anaesthetic conditions.

Visual disturbances during transurethral resection of the prostate

Abstract: We present a case of temporary blindness without mental changes following over-hydration during transurethral resection of the prostate. The symptoms suggest oedema of the occipital cortex.

Disinfection of anaesthesia equipment by a mechanized pasteurization method.

Abstract: Using a technique of artificial contamination of anaesthetic breathing tubes we have examined the bacteriological efficacy of a mechanized hot water pasteurization process which involves use of an automatic clothes washing machine. Organisms tested were Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus faecalis. Contamination was massive, greater than 108 organisms/ml. Following pasteurization, 88 of 96 breathing tubes showed no growth of the test organisms while recovery of bacteria in the remaining 8 was at the rate of less than 1 organism/40 ml. Pasteurization provides a relatively simple and reliable method of disinfecting some types of anaesthetic equipment, in the absence of other more effective methods.

The use of spontaneous continuous positive airway pressure (CPAP) for reduction of intrapulmonary shunting in adults with acute respiratory failure

Abstract: A discussion of the indications for and technique and effects of spontaneous CPAP are presented, showing its value in the treatment of hypoxaemia, using a basically simple system. A series of patients are presented showing a typical clinical course.

Direct arterial pressure monitoring from the dorsalis pedis artery.

Abstract: The arteria dorsalis pedis, when clearly palpable, is a suitable artery for direct arterial blood pressure monitoring. The systolic pressure and the pulse pressure are likely higher in the dorsalis pedis artery when compared to the radial artery but there is no clinically significant difference in mean pressures. In plethysmographic studies it was found that in 16 per cent of the patients examined the pulse in the second toe disappeared after occlusion of the dorsalis pedis artery indicating that it carried the main blood supply to the toes. Although no complications have resulted from cannulation of the dorsalis pedis artery in our practise, some caution is in order and preliminary testing may be advisable even if the posterior tibial artery is distinctly palpable.

The effects of morphine and halothane anaesthesia on urine norepinephrine during and after coronary artery surgery.

Abstract: Urine concentrations and excretion rates of norepinephrine were measured in 28 patients anaesthetized with halothane or morphine before, during and for two hours after aortocoronary artery grafting procedures. All patients were paralyzed with d-tubocurarine, incubated and respiration was controlled. Urine was obtained for 90 minutes before induction, during induction, before, during and after bypass and postoperatively. In patients anaesthetized with halothane, urinary norepinephrine concentrations and excretion rates were not significantly different from preoperative values until the postoperative period. Patients anaesthetized with morphine did not have urine norepinephrine concentrations different from preoperative values until bypass, when they became significantly increased. All subsequent urine norepinephrine concentrations and excretion rates were significantly elevated when compared to preoperative values. These findings do not indicate a mechanism but they do demonstrate that morphine anaesthesia is associated with increased urinary and probably also increased plasma levels of norepinephrine during and after cardiopulmonary bypass in patients undergoing coronary artery operations.

Concentration of lidocaine hydrochloride in newborn gastric fluid after elective caesarean section and vaginal delivery with epidural analgesia

Abstract: Lidocaine concentrations were measured after vaginal delivery or Caesarean section with epidural anaesthesia in samples of maternal and umbilical blood and in newborn gastric contents. The pH of the gastric aspirate was also determined in a number of neonates. Gastric lidocaine concentrations were higher and the pH was lower after vaginal delivery in comparison to Caesarean section. A significant inverse correlation exists between gastric pH and gastric lidocaine concentration. Neonate gastric lidocaine concentration was significantly higher than in maternal or umbilical venous plasma after vaginal delivery, but not after Caesarean section. Due to these differences, gastric lavage for the treatment of neonatal lidocaine intoxication may be more beneficial in reducing foetal systemic local anaesthetic concentration after vaginal than after elective abdominal delivery.

The effects of continuous positive pressure ventilation on pulmonary oedema, gas exchange and lung mechanics.

Abstract: The effect of continuous positive pressure ventilation was studied in 23 dogs in whom pulmonary oedema was induced by rapid intravenous infusion of dextran 40. CPPV slowed but did not prevent the formation of oedema.