Showing papers in "BJA: British Journal of Anaesthesia in 1968"
TL;DR: In the early postoperative period, oxygen consumption was close to basal in fourteen non-shivering patients but raised within the range 135–486 per cent in ten shivering patients, and there was no correlation between oxygen consumption and arterial Po2.
Abstract: SUMMARY In the early postoperative period, oxygen consumption was close to basal (range 71–135 per cent of basal) in fourteen non-shivering patients but raised within the range 135–486 per cent in ten shivering patients. There was no correlation between oxygen consumption and arterial Po2, which ranged from 57 to 89 mm Hg in non-shivering patients and from 61 to 96 mm Hg in shivering patients. In every case, ventilation was adequate for the increased metabolic demand of shivering and the highest arterial Pco2 was 42.6 mm Hg. Two non-shivering patients had Pco2 of 46 and 52 mm Hg respectively. In two out of three shivering patients, cardiac output was adequate for demand and mixed venous oxygen content was within the normal range. In the third shivering patient, a cardiac output of 9.4 l./min was inadequate for an oxygen consumption of 1,192 ml/min and the arterial/mixed venous oxygen content difference was 12.7 ml/100 ml. This was a factor in the associated arterial hypoxaemia (65 mm Hg). In other patients arterial Po2 was mainly influenced by venous admixture which ranged from 3.5 to 13.8 per cent.
213 citations
TL;DR: The large fall in cardiac output found may, if unaccompanied by a decrease in oxygen utilization, augment the alveolar-arterial oxygen tension differences by causing a decreases in the mixed venous oxygen tension.
Abstract: Anaesthetized, laterally recumbent horses were found to have large alveolar-arterial oxygen tension differences. These differences had a rapid onset following the induction of anaesthesia and remained constant during the anaesthetic period both in horses breathing spontaneously and in those subjected to intermittent positive pressure ventilation. It is suggested that the differences may result from mismatching of ventilation and perfusion due to the effect of gravity on the pulmonary circulation and restricted ventilation of the lower lung. The large fall in cardiac output found may, if unaccompanied by a decrease in oxygen utilization, augment the alveolar-arterial oxygen tension differences by causing a decrease in the mixed venous oxygen tension.
166 citations
TL;DR: It is concluded that ICI.50,172 can safely be administered to asthmatic patients and that its introduction could represent an important advance in beta blocking therapy.
Abstract: A new beta-adrenergic receptor blocking agent, ICI.50,172, has been compared with propranolol with respect to the effects on airway resistance (AWR), forced expiratory volume (FEV1) and pulse rate. AWR was measured by body plethysmography. The drugs were given intravenously to ten asthmatic patients on different occasions. ICI.50,172 caused no subjective alteration of their respiratory condition, and only a slight increase in AWR. Propranolol caused dyspnoea and wheeze in all but one of the subjects together with a marked increase in AWR. It is concluded that ICI.50,172 can safely be administered to asthmatic patients and that its introduction could represent an important advance in beta blocking therapy.
103 citations
TL;DR: Diazepam has been studied as an intravenous induction agent in intermittent and sinle doses and there was a remarkable absence of cardiovascular or other side effects, even from very large doses, and amnesia was also an outstanding feature.
Abstract: SUMMARY Diazepam has been studied as an intravenous induction agent in intermittent and sinle doses. There is a delay of about 1 minute in onset of the soporific effect, and a great individual variation in response to the drug. Even with doses up to 0.8 mg/kg it was not possible to guarantee induction of anaesthesia. There was a remarkable absence of cardiovascular or other side effects, even from very large doses, and amnesia was also an outstanding feature. The eventual place of diazepam in anaesthesia will not be as a competitor with established induction agents.
91 citations
TL;DR: The frequency and type of laryngeal pathology suggest that therapeutic intubation should not be used for more than a few hours if there is not a strong indication for an artificial airway, but the incidence of damage is not so high as to contraindicate a prospective study comparing it with tracheostomy under apparently the same conditions.
Abstract: SUMMARY In recent years there has been an increased use of therapeutic intubation. It is especially useful in conscious patients postoperatively for periods of a day or so when the need for respiratory assistance is short-lived. It can be utilized for many days but the likelihood of laryngeal damage is probably increased, although in the individual case the shortness of the period of intubation is no guarantee of laryngeal safety. Whether the advantages of prolonged intubation outweigh the disadvantages can only be decided when the results of a series of carefully followed-up cases of prolonged intubation can be compared with those of a series of patients who have a tracheostomy inserted early in their treatment and for approximately the same length of time as the endotracheal tube. The frequency and type of laryngeal pathology suggest that therapeutic intubation should not be used for more than a few hours if there is not a strong indication for an artificial airway, but the incidence of damage is not so high as to contraindicate a prospective study comparing it with tracheostomy under apparently the same conditions.
73 citations
TL;DR: It is discussed that the high-threshold inflation receptors may be involved in some of the reflex effects that have been observed during surgical anaesthesia with high concentrations of halothane.
Abstract: The effect of halothane, ether, chloroform and trichloroethylene on the impulse discharge of two types of pulmonary receptor has been investigated in cats and dogs under chloralose or barbiturate anaesthesia. Afferent impulses were recorded from pulmonary stretch fibres and also from slowly-conducting vagal fibres whose pulmonary endings were stimulated by hyperinflation (high-threshold inflation receptors). Ventilating the lungs with low concentrations of each agent (e.g. 1–3 per cent halothane) caused sensitization of the pulmonary stretch receptors but had no effect on the high-threshold endings. With high concentrations (e.g. 5–20 per cent halothane), pulmonary stretch receptors showed an initial sensitization followed by a reduction or abolition of activity, while the high-threshold receptors showed a marked increase in impulse activity during inflation. The possibility is discussed that the high-threshold inflation receptors may be involved in some of the reflex effects that have been observed during surgical anaesthesia with high concentrations of halothane.
61 citations
TL;DR: A case is advanced for recording alveolar Pco2 during air-breathing and taking the increase above normal as the measure of respiratory depression and measuring oxygen consumption as pan of the assessment of the effect of a drug on respiration.
Abstract: The methods currently employed for the assessment in normal human subjects of the respiratory effects of drugs are briefly reviewed; the diversity of criteria of depression is indicated, with reference to the many types of test for ventilatory response to inspired carbon dioxide. A case is advanced, with support from the results of control measurements, for (1) recording alveolar Pco2 during air-breathing and taking the increase above normal as the measure of respiratory depression and (2) measuring oxygen consumption as pan of the assessment of the effect of a drug on respiration. A method is described which has been used for making measurements before and after drug administration; the results of control studies using this method are presented: values for PAco2 varied least, and parameters of a rebreathing carbon dioxide response test varied most, among the several measurements of ventilatory function.
56 citations
TL;DR: The oesophageal temperature recorded in the anaesthetized and intubated adult depends on the site at which it is taken and is both the warmest and the most stable.
Abstract: The oesophageal temperature recorded in the anaesthetized and intubated adult depends on the site at which it is taken. The longitudinal variation is greater than the lateral and can be as much as 6°C. The lowest temperatures are found in the upper and middle thirds. Both longitudinal and lateral variations level out in the lower third. The lower fourth of the oesophagus is both the warmest and the most stable. To reach this area, thermocouple leads should be inserted at least 24 cm below the comiculate cartilages.
55 citations
TL;DR: Prolongation of anaesthesia in subjects with low enzyme activity corresponded with the e.e.g. findings, and it is recommended that a dose of 3–4 mg/kg of Epontol is sufficient for induction of anaesthetic in high-risk patients.
Abstract: SUMMARY The concentration of propanidid in human serum was determined and was found to depend on the rate of injection. None was found 25 minutes after injection over a 20-second period. Propanidid passed the placental barrier, the umbilical vein concentration depending on the dose injected. Serum cholinesterase was inhibited by propanidid both in vivo and in vitro; the red-cell esterase was also inhibited. The concentration in umbilical vein blood was highest in mothers with reduced cholinesterase activity. The duration of anaesthesia appears to be influenced by serum cholinesterase activity. In vitro, enzymatic hydrolysis in human serum was slow but occurred rapidly in purified concentrated cholinesterase. When suxamethonium was injected after Epontol the period of apnoea was increased and this is ascribed to enzyme inhibition. The e.e.g. was useful in determining the duration of anaesthesia. Prolongation of anaesthesia in subjects with low enzyme activity corresponded with the e.e.g. findings. Propanidid is bound to plasma proteins and it is recommended that a dose of 3–4 mg/kg of Epontol is sufficient for induction of anaesthesia in high-risk patients.
53 citations
TL;DR: The immediate and late complications of prolonged nasotracheal intubation in eighty-three children are reviewed and it is recommended that intUBation be carried out as gently as possible, using the smallest tube which will permit adequate ventilation, and that the duration of intubations should not exceed seven days.
Abstract: SUMMARY The immediate and late complications of prolonged nasotracheal intubation in eighty-three children are reviewed. Twenty-six of the thirty survivors were examined by laryngoscopy to determine the incidence of permanent laryngeal lesions. Seventeen had no lesion. Of the remaining nine, two had severe subglottic stenosis, four slight subglottic stenosis, and three minor degrees of scarring without narrowing. In order to prevent these complications arising, it is recommended that intubation be carried out as gently as possible, using the smallest tube which will permit adequate ventilation, and that the duration of intubation should not exceed seven days.
52 citations
TL;DR: There were no significant differences in age, sex, duration and type of procedure, anaesthetic dose, and levels of oxygenation in the two groups which could account for the observed results.
Abstract: To study the effect of hypocarbia during anaesthesia on postoperative performance of a reaction time test, thirty-seven selected surgical patients were anaesthetized in a manner which does not alter cerebral blood flow at normal arterial Pco2 levels Patients were hyperventilated and variable amounts of carbon dioxide (0–2 per cent) were added to the inspired mixture to obtain a steady Paco2 A range of Paco2 of 12 to 38 mm Hg was obtained in the thirty-seven patients In twenty patients whose Paco2 was below 24 mm Hg throughout the procedure there was postoperative prolongation of reaction time which lasted 3 to 6 days Seventeen patients, whose Paco2 was greater than 24 mm Hg did not demonstrate this prolongation There were no significant differences in age, sex, duration and type of procedure, anaesthetic dose, and levels of oxygenation in the two groups which could account for the observed results
TL;DR: The effects of posture upon circulatory haemodynamics in late pregnancy and their importance to the anaesthetist are discussed in relation to conscious patients, during general anaesthesia and following epidural or spinal blockade.
Abstract: SUMMARY The effects of posture upon circulatory haemodynamics in late pregnancy and their importance to the anaesthetist are discussed in relation to conscious patients, during general anaesthesia and following epidural or spinal blockade.
TL;DR: An anaesthetic system incorporating the principle of kinetic energy of gas flow has been developed for use during intermittent positive pressure respiration in paediatric anaesthesia that has no moving parts, is of small bulk and has minimum deadspace and resistance to respiration.
Abstract: SUMMARY An anaesthetic system incorporating the principle of kinetic energy of gas flow has been developed for use during intermittent positive pressure respiration in paediatric anaesthesia. The advantages of the system are that it has no moving parts, is of small bulk and has minimum deadspace and resistance to respiration. The major disadvantage of the system is the large gas flows required particularly in the presence of a low compliance or a small endotracheal tube. The system has been used during anaesthesia and in three cases who required prolonged mechanical ventilation.
Journal Article•
TL;DR: The hypoxaemia was associated with increased alveolar-arterial differences in oxygen tension, and with large values for the "physiological deadspace" these indicated irregular ventilation-perfusion relationships.
Abstract: SUMMARY Studies were made of the ventilation and arterial acid-base balance of twenty-three patients who had suffered severe head injuries. The most frequent findings were an increased minute volume, an increased production of carbon dioxide, an arterial hypoxaemia, hypocapnia and a raised arterial pH. There was no instance of respiratory acidosis, and only three patients showed normal ventilation and acid-base values. The increased minute volume was associated not only with an increased carbon dioxide production, but also with a reduced arterial carbon dioxide tension and, therefore, with an increased alveolar ventilation, which may be due to hypoxaemia or to central factors which were not investigated. The hypoxaemia was associated with increased alveolar-arterial differences in oxygen tension, and with large values for the "physiological deadspace" these indicated irregular ventilation-perfusion relationships. Aspiration andatelectasis at the time of the head injury may initiate the hypoxaemia, the increase in ventilation, and the arterial respiratory alkalosis which have been recorded.
TL;DR: There was a positive correlation between the tubocurarine requirements and the serum level of gamma globulin and the electrophoretic serum protein pattern in 52 adult patients undergoing upper abdominal surgery under nitrous oxide and oxygen anaesthesia.
Abstract: SUMMARY The correlation between tubocurarine requirements and the electrophoretic serum protein pattern was investigated in 52 adult patients undergoing upper abdominal surgery under nitrous oxide and oxygen anaesthesia. There was a positive correlation between the tubocurarine requirements (mg/kg) and the serum level of gamma globulin; r = +0.604, which is highly significant (P
TL;DR: The rises in Pco2 provided a guide to respiratory depression which was as consistent and as statistically significant as most quoted changes in parameters of carbon-dioxide response tests.
Abstract: SUMMARY Three drugs and saline were given intravenously, on separate occasions, to eight normal subjects. The doses used were pentazocine 20 mg, phenoperidine 1.5 mg and morphine sulphate 10 mg, each per 70 kg body weight End-tidal Pco2 and ventilatory pattern were followed continuously; expired volume and oxygen consumption were measured before and at intervals after injection; a rebreathing carbon-dioxide response test was also applied. The three drugs produced similar, and significant increases, of the order of 5 torr in Pco2 and dissimilar, significant, reductions in ventilation which could be related to dissimilar effects on oxygen consumption: injection of morphine or of phenoperidine was followed within 10 minutes by an average reduction in oxygen consumption by 20–30 per cent whereas after pentazocine the reduction was only about 10 per cent. The rises in Pco2 provided a guide to respiratory depression which was as consistent and as statistically significant as most quoted changes in parameters of carbon-dioxide response tests. The results of the carbon dioxide-response test used in this trial were very variable.
TL;DR: Epidural analgesia has a valuable therapeutic role in obstetrics and is one of the benefits which result from the introduction of a 24-hour resident obstetric anaesthetic service.
Abstract: SUMMARY Experiences with 300 continuous and 62 single-shot epidural blocks administered during labour are presented. The main indications for continuous epidural analgesia were inco-ordinate uterine action, severe pre-eclampsia and failure of orthodox analgesic drugs to produce satisfactory pain relief. The method can also be used with benefit in selected cases of cardiac and respiratory disease. In hypertonic inco-ordinate uterine action graphical analysis of labour demonstrates an increased rate of cervical dilatation after epidural block in 70 per cent of cases. In pre-eclampsia a satisfactory reduction of systolic and diastolic blood pressure is produced. Analgesia is virtually complete and the complication rate is acceptably low in experienced hands. Single-shot epidural analgesia is excellent for forceps delivery and blood loss at delivery is reduced. Epidural analgesia has a valuable therapeutic role in obstetrics and is one of the benefits which result from the introduction of a 24-hour resident obstetric anaesthetic service.
TL;DR: It is suggested that patients receiving monoamine oxidase inhibitors who require an operation should undergo a sensitivity test to morphine.
Abstract: SUMMARY Fifteen patients being treated with monoamine oxidase inhibitors were given injections of pethidine, morphine and water in a random order. Every patient received a series of four injections of each of these, in increasing doses and at 45-minute intervals. As judged from measurements of their blood pressure and pulse rate, and from observation of the general state of awareness, all patients reacted normally. It is suggested that patients receiving monoamine oxidase inhibitors who require an operation should undergo a sensitivity test to morphine.
TL;DR: The claims that these drugs are capable of allaying pre-operative apprehension were fully substantiated and chlordiazepoxide 100 mg achieved this with very little soporific effect.
Abstract: SUMMARY Two benzodiazepine tranquillizers, chlordiazepoxide (50 and 100 mg) and diazepam (10 and 20 mg) were studied under standard conditions in females, as single-dose premedicants before a standard operation. The findings were compared with those obtained using saline and with previously reported data using opiates and phenothiazine derivatives. The claims that these drugs are capable of allaying pre-operative apprehension were fully substantiated and chlordiazepoxide 100 mg achieved this with very little soporific effect. The action of these drugs was as good as that of most opiates and side effects were much fewer. The eventual place for them may be for use as a "pre-preanaesthetic-medication" given by mouth on the day before operation.
TL;DR: The more potent the drug the safer it is with respect to the sequelae of intra-arterial injection because it can be used in a more dilute solution, and diis was less likely to occur with low concentrations.
Abstract: SUMMARY A study was made of the effects of mixing thiopentone and mediohexitone with blood in the proportions likely to occur in accidental intra-arterial injection of die barbiturates. In addition to crystal formation, which had been previously reported, red blood cell haemolysis and platelet aggregation also occurred. Since these all lead to intravascular clotting the damaging effect of intra-arterial injection of barbiturates could be explained on this basis. On the basis of a further study of the crystal-forming properties of the commercially available barbiturates in aqueous solutions at differing dilutions, it was concluded that diis was less likely to occur with low concentrations. Thus the more potent the drug the safer it is with respect to the sequelae of intra-arterial injection because it can be used in a more dilute solution.
TL;DR: It is well accepted that nitrous oxide is satisfactory for the relief of pain in labour and to provide analgesia for conservative dental procedures and its use has been extended, too, to include pain in myocardial ischaemia, acute trauma, and after surgical operations.
Abstract: SUMMARY Administration of nitrous oxide in order to provide analgesia is now more practicable because improved apparatus is available. It is well accepted that nitrous oxide is satisfactory for the relief of pain in labour and to provide analgesia for conservative dental procedures. Its use has been extended, too, to include pain in myocardial ischaemia, acute trauma, and after surgical operations. Apart from its value in mitigating pain, its value in other conditions is considered. These include the management of head injuries, bronchial asthma and some neoplastic conditions. The principal limitation of nitrous oxide therapy is that continuous treatment must be limited to 24 or at the most 48 hours because of the risk of leucopenia.
TL;DR: The method used in a long-continuing study of drugs given as premedication to healthy patients undergoing minor gynaecological operations has been reviewed in order to evaluate the importance of various potential sources of bias.
Abstract: SUMMARY The method used in a long-continuing study of drugs given as premedication to healthy patients undergoing minor gynaecological operations has been reviewed in order to evaluate the importance of various potential sources of bias. Factors which were found not to have influenced the results, in the context of the standard method used throughout the study, included the subject's body weight and age, and the use of different observers. Those factors which did affect the outcome included the frequency of pre-operative visits of the subject by the observer, the precise nature of the operation performed, and the duration of anaesthesia. These considerations are discussed in the light of the design of similar clinical trials.
TL;DR: Reductions in arterial pressure caused by the anaesthetics influenced these results, increased chemoreceptor activity, and could overcome the effects of blood gas changes.
Abstract: SUMMARY In cats anaesthetized with pentobarbitone, the left carotid sinus was denervated by dissection of baroreceptor elements, and the mean integrated carotid body chemoreceptor discharge was recorded Chemoreceptor response curves to altered Pao2 at constant end-tidal Pco2, and to altered Paco2 at constant Pao2, were plotted before and during pulmonary ventilation with diethyl ether, cyclopropane, or halothane The response curves were tilted in the direction of chemoreceptor stimulation by cyclopropane and by ether, while halothane appeared to depress the discharge In no instance did the inhalation anaesthetics increase chemoreceptor activity above the maximum attainable by blood gas changes alone Reductions in arterial pressure caused by the anaesthetics influenced these results, increased chemoreceptor activity, and could overcome the effects of blood gas changes
TL;DR: Factors which can lead to awareness during surgery are considered and a circle system is shown to need time to acquire an adequate concentration of anaesthetic.
Abstract: SUMMARY Factors which can lead to awareness during surgery are considered. They are divided into those affecting induction and those affecting maintenance. Induction: The risk of a patient recovering consciousness while still paralyzed is greater if an ultrashort-acting intravenous anaesthetic is used. The time interval necessary before surgery may begin is governed by the need to build up a sufficient concentration of inhalation agent to take over from the waning effect of the intravenous agent. Maintenance: Three sources of trouble are distinguished, each leading to the patient receiving an anaesthetic mixture less potent than intended. (1) Ventilators may mix air or oxygen with the anaesthetic gas if they are not adjusted properly or if there are leaks. Ventilators are classified according to their propensities for doing this. (2) Some anaesthetic machines have pitfalls. (3) A circle system is shown to need time to acquire an adequate concentration of anaesthetic. The importance of high flowrates is stressed both at the start of an anaesthetic and also if the circuit should happen to be broken later on.
TL;DR: The authors review the present evidence for the transplacental passage of tubocurarine and suggest that previous work may not represent the situation accurately.
Abstract: SUMMARY A case is reported in which tubocurarine crossed the placental barrier and paralyzed a 28-week foetus. The mother was under treatment for status epilepticus. The authors review the present evidence for the transplacental passage of tubocurarine and suggest that previous work may not represent the situation accurately. Reference is made to a further case which also suggests transplacental passage of tubocurarine, this time in the first trimester of pregnancy.
TL;DR: An electrocardiographic study on the effect of atropine-neostigmine mixture was carried out on thirty-one curarized patients under nitrous oxide and oxygen anaesthesia, finding that it caused no cardiac hazards.
Abstract: SUMMARY An electrocardiographic study on the effect of atropine-neostigmine mixture was carried out on thirty-one curarized patients under nitrous oxide and oxygen anaesthesia. Adequate oxygenation and carbon dioxide elimination was ensured during reversal and injection of a mixture of atropine (0.02 mg/kg) and neostigmine (0.05 mg/kg) caused no cardiac hazards.
TL;DR: The Servomex OA.150 paramagnetic oxygen analyzer has been assessed and found to possess features which make it suitable for the analysis of gas samples of not less than 50 mL and for greater accuracy a four- or even five-figure read-out is recommended in order to utilize the basic sensitivity of this instrument.
Abstract: Paramagnetism is described and discussed in relation to the measurement of oxygen tension in gases. In medical practice the need for a comparatively cheap instrument which will accurately measure the oxygen concentration in gas mixtures has been felt by both clinical and laboratory workers. The Servomex OA.150 paramagnetic oxygen analyzer has been assessed and found to possess features which make it suitable for the analysis of gas samples of not less than 50 mL For greater accuracy a four- or even five-figure read-out is recommended in order to utilize the basic sensitivity of this instrument. Some problems concerning its use for long-term monitoring are discussed.