Showing papers in "BJA: British Journal of Anaesthesia in 1974"
TL;DR: The results confirm the presence of a markedly increased oxygen consumption at term and emphasize the importance in obstetric anaesthesia of preoxygenation before and of prompt reoxygenations following endotracheal intubation.
Abstract: The decrease in arterial oxygen tension, during 60 sec of apnoea with exposure to room air, was studied in twelve healthy parturient women undergoing Caesarean section under endotracheal fluroxene-oxygen anaesthesia. Eight young gynaecological patients, anaesthetized in an identical manner, served as controls. The reduction in oxygen tension was significantly greater in the pregnant women than in the controls and was greatest in women in labour. The results confirm the presence of a markedly increased oxygen consumption at term and emphasize the importance in obstetric anaesthesia of preoxygenation before and of prompt reoxygenation following endotracheal intubation.
159 citations
TL;DR: The helium dilution technique has been used to measure the FRC of 13 patients before and during anaesthesia with paralysis and artificial ventilation, and also in 5 conscious subjects during spontaneous andificial ventilation without paralysis.
Abstract: The helium dilution technique has been used to measure the FRC of 13 patients before and during anaesthesia with paralysis and artificial ventilation, and also in 5 conscious subjects during spontaneous and artificial ventilation without paralysis. After induction of anaesthesia the mean reduction in FRC was 297 ml or 15.4% of the preoperative value and the change was highly significant (P
102 citations
TL;DR: Mucus flow rates were measured in the intact trachea of anaesthetized dogs, using a radioactive tracer technique, and no significant difference in mucus flow rate was found.
Abstract: Mucus flow rates were measured in the intact trachea of anaesthetized dogs, using a radioactive tracer technique. Measurements were made before intubation, and after intubation at inspired air temperatures of 32, 37 and 42°C, with a constant inspired water vapour content of 33 mg/l.; and again at each temperature with a relative humidity of 75%. No significant difference in mucus flow rate was found under any of these conditions.
96 citations
TL;DR: Four of 8 baboons given sodium nitroprusside in a study of induced hypotension failed to recover normal arterial pressure after discontinuance of i.v. infusion; instead arterial Pressure continued to decrease progressively and irreversibly.
Abstract: Four of 8 baboons given sodium nitroprusside in a study of induced hypotension failed to recover normal arterial pressure after discontinuance of i.v. infusion; instead arterial pressure continued to decrease progressively and irreversibly. Other features noted in these animals were metabolic acidosis in both arterial blood and cerebrospinal fluid, and a markedly depressed cerebral oxygen uptake. In comparing this "non-recovery" group of animals with the other 4 baboons, in which arterial pressure recovered rapidly after discontinuance of nitroprusside infusion, it was found that the mean nitroprusside dose in the former was 4–6 times that used in the latter. The animals showing a "normal" response received doses of nitroprusside which, after correction for body weight, were similar to those used clinically. On the same weight correction basis, the smallest toxic dose in the baboon given over 1½–¾4 hours would be equivalent to 320 mg/hr in man and the mean toxic dose equivalent to 518 (SE 122) mg/hr. Caution is advocated in the use of high doses of sodium nitroprusside in patients who appear resistant to its hypotensive action. The appearance of a systemic acidosis may be an indication that the dose administered is nearing the toxic range.
92 citations
TL;DR: The patient had no previous neurological abnormality and it is postulated that vascular ischaemia of the spinal cord was responsible for the sequence of neurological events.
Abstract: Paraplegia complicating a block of the coeliac plexus with 6% aqueous phenol for carcinoma of the pancreas is described. The patient had no previous neurological abnormality and it is postulated that vascular ischaemia of the spinal cord was responsible for the sequence of neurological events.
84 citations
TL;DR: Haemodynamic measurements and estimates of pulmonary gas exchange have been made in 15 patients during varying degrees of deliberate arterial hypotension induced by IPPV with varying concentrations of halothane in oxygen, which indicate a dose-dependent impairment of the contractile function of the myocardium.
Abstract: Haemodynamic measurements and estimates of pulmonary gas exchange have been made in 15 patients during varying degrees of deliberate arterial hypotension induced by IPPV with varying concentrations of halothane in oxygen. Used in this way, halothane caused a dose-dependent arterial hypotension, which was directly related to a reduction in stroke volume and cardiac output, raised right atrial pressures, but insignificant changes in either heart rate or systemic vascular resistance. The findings are not compatible with the concept that the hypotensive effects of halothane are due to “vaso-dilatation”, but are compatible with the results of animal studies which indicate a dose-dependent impairment of the contractile function of the myocardium.
83 citations
77 citations
TL;DR: Two groups of children, comparable in age and weight, underwent normal preoperative starvation and received milk orally 4 hours prior to operation, and Hypoglycaemia occurred only in those children in the SG who were less than 47 months of age and 15.5 kg body weight.
Abstract: Two groups of children, comparable in age and weight were studied. The first, the Starvation Group (SG), underwent normal preoperative starvation. The second, the Milk Group (MG), received milk orally 4 hours prior to operation. At operation the mean blood glucose concentration was 53.3 mg/100 ml in the SG and 66.4 mg/100 ml in the MG. The difference between the two groups was statistically significant. Hypoglycaemia occurred only in those children in the SG who were less than 47 months of age and 15.5 kg body weight.
77 citations
TL;DR: Functional residual capacity has been measured by helium dilution in 26 spontaneously breathing patients before and immediately after anaesthesia, which was induced with thiopentone and maintained with halothane and the change was highly significant and correlated with age.
Abstract: Functional residual capacity has been measured by helium dilution in 26 spontaneously breathing patients before and immediately after anaesthesia, which was induced with thiopentone and maintained with halothane. The mean reduction was 390 ml (16.1% of pre-induction value) and the change was highly significant (P
68 citations
TL;DR: The increasing use of modern techniques for monitoring intracranial and systemic arterial pressures has shown that considerable changes can occur in these two parameters during a number of anaesthetic manoeuvres.
Abstract: The increasing use of modern techniques for monitoring intracranial and systemic arterial pressures has shown that considerable changes can occur in these two parameters during a number of anaesthetic manoeuvres. However, although sharp increases in both pressures have been documented during the induction of anaesthesia and during the initial surgery in patients undergoing craniotomy (1), less attention has been paid to those changes taking place during the conclusion of anaesthesia (2). It is reasonably held that, following internal decompression, the changes in intracranial pressure are minimal in the immediate post-surgical phase. However, in view of the clinical deterioration that can occur occasionally at this stage, it seemed worth while investigating the sequence of events which take place during the termination of anaesthesia, to determine if significant changes in intracranial or arterial pressure occur.
67 citations
TL;DR: Cardiac output was varied in normal dogs and in dogs with oleic acid induced pulmonary oedema by inducing hyper- and hypovolaemia produced by either transfusing or bleeding 15–20 ml of blood per kg body weight from the normovolaemic state by means of veno-venous shunting of blood through a disc oxygenator.
Abstract: Cardiac output was varied in 6 normal dogs and in 12 dogs with oleic acid induced pulmonary oedema by inducing hyper- and hypovolaemia produced by either transfusing or bleeding 15–20 ml of blood per kg body weight from the normovolaemic state. In normal dogs, a reduction in cardiac output of 42% was accompanied by a reduction in intrapulmonary shunt (Qs/Qt) from 9.8 to 6.4%. With induced pulmonary oedema, a 35% reduction in cardiac output was accompanied by a fall in Qs/Qt from 29 to 21.6%. In another series of experiments, mixed venous oxygen saturation was varied independently of cardiac output by means of veno-venous shunting of blood through a disc oxygenator. Decreasing SvO2 from 70 to 50% in normal lungs caused a decrease in QS/QT from 10.1 to 7.9% whilst in pulmonary oedema a decrease in Sv02 from 59.3 to 32.2% produced a decrease in Qs/Qt from 10.1 to 7.9% whilst in pulmonary oedema a decrease in SvO2 from 59.3 to 32.2% produced a decrease in Qs/Qt from 28.8 to 25.7%.
TL;DR: An increase in shunt between the beginning and the end of the operation was found to correlate with a fall in the ventilation volume of the dependent lung during OLV, probably because of uptake of residual oxygen in the unventilated lung.
Abstract: The efficiency of arterial oxygenation was assessed at different stages during noncardiac thoracic surgery in 17 patients who had been intubated with Robertshaw double-lumen endobronchial tubes. Arterial oxygen tension (Pao2), "ideal" alveolar to arterial oxygen tension differences (PAo2 —Pao2), arteriovenous oxygen content differences (Cao2 —Cvo2) and physiological shunt (QS/QT) were measured during ventilation with halothane/oxygen mixtures. Highly significant decreases in Pao2 and increases in QS/QT occurred during periods of one-lung ventilation (OLV), although the changes were significantly greater in a group of patients who were undergoing exploratory thoracotomy and non-pulmonary surgery (non-resection group) than in those undergoing lobectomy or pneumonectomy (resection group). Four out of seven patients in the non-resection group had a Pao2 of less than 80 mm Hg during OLV and the mean shunt in this group was over 40%. In both groups the shunt measured within 10 min of the commencement of OLV was significantly smaller than values obtained after 10–30 min of OLV, probably because of uptake of residual oxygen in the unventilated lung. An increase in shunt between the beginning and the end of the operation was found to correlate with a fall in the ventilation volume of the dependent lung during OLV.
TL;DR: In this paper, the authors measured the ability of participants to discriminate the fusion of flickering light, and concluded that patients should not drive or operate machinery for 10 hours after i.v. injection of diazepam and 24 hours after flunitrazepam and droperidol.
Abstract: Skills related to driving and the ability to discriminate the fusion of flickering light were measured double-blind in 62 healthy volunteer students before and 4, 6, 8 and 10 hours after intravenous injection of diazepam (0.3 mg/kg), flunitrazepam (0.03 mg/kg) or droperidol (5 mg), alone or in combination with pethidine (1 mg/kg) or fentanyl (0.2 mg). The dose of diazepam and flunitrazepam was halved in those subjects given pethidine but the dose of droperidol was the same with and without fentanyl. Impairment by droperidol in almost all tests remained up to 10 hours after injection. Droperidol proved more deleterious than the benzodiazepines. Flunitrazepam impaired flicker fusion discrimination and co-ordination for up to 10 hours. Diazepam impaired flicker fusion discrimination and co-ordination for up to 6 hours. The doses of narcotic analgesics used here did not enhance the effect of other drugs on performance in the tests used. It is concluded that patients should not drive or operate machinery for 10 hours after i.v. injection of diazepam and 24 hours after flunitrazepam and droperidol.
TL;DR: There was no significant decrease in cerebral blood flow, as determined by measurement of grey matter flow, or change in the cerebral metabolic rate for oxygen when the blood pressure was reduced by 42%.
Abstract: Cerebral blood flow and metabolism have been studied during hypotension induced with sodium nitroprusside in 20 patients undergoing surgery for cerebral aneurysms. Cerebral blood flow was measured using an injection of xenon-133 into the common carotid artery, after the retrograde cannulation of the superficial temporal artery, and exponential stripping of the decay curve as detected by a scintillation counter placed over the ipsilateral fronto-parietal region. In the group as a whole there was no significant decrease in cerebral blood flow, as determined by measurement of grey matter flow, or change in the cerebral metabolic rate for oxygen when the blood pressure was reduced by 42%. Cerebrovascular resistance decreased by 40%. During hypotension there were significant decreases in arterial oxygen tension, arterial and jugular venous oxygen contents, but insignificant decreases in jugular venous oxygen tension and arterio-jugular venous oxygen content difference. There were no complications that could be attributed to sodium nitroprusside.
TL;DR: During nitrous oxide anaesthesia, the tendency of closed body air cavities is to increase in size and/or pressure until equilibrium prevails, which indicates thatNitrous oxide is not an innocuous agent and, in certain situations, may be contraindicated.
Abstract: The characteristic feature of body air cavities is their tendency to decrease in size and ultimately disappear. During air breathing the transfer of gases from a high partial pressure within cavities to a lower partial pressure in blood forms the basis for the resorption of air spaces such as pneumoperitoneum, pneumothorax and subcutaneous emphysema (Piiper, 1965). The formation of atelectasis in closed alveoli also follows these principles. However, during nitrous oxide anaesthesia, the reverse occurs; that is, the tendency of closed body air cavities is to increase in size and/or pressure until equilibrium prevails. This effect is related to the difference in solubility between nitrous oxide and nitrogen, and accounts for a number of potential hazards during the induction, maintenance, and subsequent recovery from nitrous oxide anaesthesia. This indicates that nitrous oxide is not an innocuous agent and, in certain situations, may be contraindicated.
Journal Article•
TL;DR: The cause of jaundice was a bilirubin overload which could not be excreted effectively by a liver whose cellular metabolism was disturbed, and there was no evidence of a relationship between halothane and liver damage.
Abstract: Jaundice often complicates recovery after surgery. We have studied 180 patients undergoing 218 major operations and found an incidence of 3.7% severe jaundice and 16.5% mild jaundice. The causes of the jaundice were diverse, but the most important was a bilirubin overload (primarily from blood transfusion) which could not be excreted effectively by a liver whose cellular metabolism was disturbed. We found no evidence of a relationship between halothane and liver damage.
TL;DR: Direct tracheoscopy was employed to assess tracheal damage following prolonged intubation and comparison of conventional and low-pressure cuffs showed that there was less trauma from the low- pressure cuff.
Abstract: Direct tracheoscopy was employed to assess tracheal damage following prolonged intubation. Comparison of conventional and low-pressure cuffs showed that there was less trauma from the low-pressure cuff. Comparison of tube sizes showed a reduction in injury with 8-mm diameter tubes compared with larger ones.
TL;DR: Investigations of ketamine's mechanism of action were undertaken using the guineapig tracheal chain, a preparation which reacts to drugs in a manner similar to that of the smooth muscle of human bronchioles, and ketamine was found to possess a direct relaxant effect on the trachesal chain.
Abstract: Ketamine is claimed to decrease airways resistance in patients suffering from broncho-constriction. Investigations of its mechanism of action were undertaken using the guineapig tracheal chain, a preparation which reacts to drugs in a manner similar to that of the smooth muscle of human bronchioles. Ketamine was found to possess a direct relaxant effect on the tracheal chain, to antagonize the spasmogenic effects of carbachol and potentiate the antispasmodic effects of adrenaline. Reduction in airway resistance after ketamine anaesthesia is probably the result of a direct relaxant effect on bronchial smooth muscle and a changed response to endogenous humoral substances.
TL;DR: Some of the subjects with mild analgesia could have been sufficiently anaesthetized for surgery if the pain of the stimulus had been increased to an unacceptably high level.
Abstract: Acupuncture analgesia was performed on 100 occasions in 35 subjects. In 10% of cases the resulting analgesia was considered just adequate for surgery, and in 65% mild analgesia was produced but insufficient for surgery, whilst in the remaining 25 % there was only minimal analgesia, if any. Some of the subjects with mild analgesia could have been sufficiently anaesthetized for surgery if the pain of the stimulus had been increased to an unacceptably high level.
TL;DR: Reduced left ventricular filling appears to preclude any increase in cardiac output despite an increase in heart rate and a marked reduction in the impedance to left Ventricular ejection.
Abstract: The cardiovascular effects of four different infusion rates (5, 10, 20 and 40 µg kg−1 min−1) of a 001% solution of sodium nitroprusside were studied in six anaesthetized dogs The animals received IPPV with 50% nitrous oxide in oxygen under four sets of conditions: (a) with 06% halothane and normocapnia, (b) with 06% halothane and hypocapnia, (c) with 12% halothane and normocapnia, and (d) with 06% halothane and s-adrenergic receptor blockade with propranolol 02 mg kg−1 Left ventricular pressure, aortic pressure and flow (electromagnetic flow transducer), pulmonary artery pressure, stroke volume, peak aortic blood acceleration and max LV dP/dt were measured Aortic input impedance, the distribution of energy during ventricular ejection and (max LV dP/dt)/IP, were calculated Sodium nitroprusside was found to have no adverse effect on myocardial contractility Reduced left ventricular filling appears to preclude any increase in cardiac output despite an increase in heart rate and a marked reduction in the impedance to left ventricular ejection
TL;DR: A patient who developed a severe metabolic acidosis following the use of sodium nitroprusside is reported, which has also been reported in baboons.
Abstract: Sodium nitroprusside has been considered to have few side effects when used to produce hypotension in anaesthesia. We report here a patient who developed a severe metabolic acidosis following its use. This complication has also been reported in baboons. As sodium nitroprusside has been used on over 600 occasions in our hospital, experience suggests this complication to be an infrequent occurrence. Nevertheless, should a metabolic acidosis be suspected during the use of sodium nitroprusside, blood-gas measurements should be made.
TL;DR: In nine patients with severe intracranial disease causing increased intrac Cranial pressure (ICP), the effects on ICP and cerebral perfusion pressure (CPP) of the following manoeuvres were studied: endotracheal intubation, addition of 50% nitrous oxide to the inspired gas after hyperventilation with oxygen and thereafter addition of halothane to the nitrousoxide/oxygen mixture.
Abstract: In nine patients with severe intracranial disease causing increased intracranial pressure (ICP), the effects on ICP and cerebral perfusion pressure (CPP) of the following manoeuvres were studied: (1) endotracheal intubation, (2) addition of 50% nitrous oxide to the inspired gas after hyperventilation with oxygen and thereafter (3) addition of halothane to the nitrous oxide/oxygen mixture. The mean "peak" increase in ICP during endotracheal intubation was 16.6 mm Hg. Critically small CPP values were prevented by an increase in arterial pressure. Nitrous oxide caused only a minor increase in ICP. Halothane caused a mean increase in ICP of 7.6 mm Hg and critically small CPP values in three patients.
TL;DR: Clinical information, and serrum cholinesterase studies using a new substrate, succinyldithiocholine, provide evidence on the aetiology of suxamethonium hypersensitivity.
Abstract: SUMMARY Forty-seven patients demonstrating prolonged apnoea after suxamethonium have been investigated in a 3-year survey carried out in south-east Scotland. Clinical information, and serrum cholinesterase studies using a new substrate, succinyldithiocholine, provide evidence on the aetiology of suxamethonium hypersensitivity. While 13 Patients possessed only variant forms of the serum enzyme, the remaining 34 patients appeared to have a catalytically active form of cholinesterase. The causes of prolonged apnoca in the latter group are discussed. The value of screening the relatives of patients with cholinesterase variants is demonstrated by the finding of 26 relatives “at risk” out of 123 screened.
TL;DR: It was calculated that the formation of Ca-lactate complexes accounts for the difference between lactic and hydrochloric acidosis and differences in the behaviour of ionized calcium between hypercapnic and lactic acidosis might contribute to the known differences in cardiovascular effects.
Abstract: The effects of various forms of acidosis on ionized calcium concentrations were investigated in vivo in rabbits and in vitro in human plasma. Calculation of least square regression equations of ionized calcium (mM) on pH yielded the following regression coefficients in human plasma: hypercapnic acidosis —0.53±0.07; hydrochloric acidosis —0.65±0.06; lactic acidosis —0.27±0.05. These findings in human plasma are roughly paralleled by those in rabbits. From stability constants it was calculated that the formation of Ca-lactate complexes accounts for the difference between lactic and hydrochloric acidosis. It is concluded that differences in the behaviour of ionized calcium between hypercapnic and lactic acidosis might contribute to the known differences in cardiovascular effects.
TL;DR: Percutaneous transtracheal ventilation using an intermittent jet of oxygen under high pressure in an 11-year-old child undergoing operation for laryngeal stenosis and a 6-year old child with mandibular facial dysostosis, who became obstructed and cyanosed in the recovery room.
Abstract: SUMMARY Two case reports describe percutaneous transtracheal ventilation using an intermittent jet of oxygen under high pressure in an 11-year-old child undergoing operation for laryngeal stenosis and a 6-year-old child with mandibular facial dysostosis, who became obstructed and cyanosed in the recovery room.
TL;DR: The duration of storage of blood in CPD or ACD did not affect the sensitivity of the red cells to haemolysis at 50°C, and blood stored in ACD Haemolyses less rapidly at50°C than blood storedIn CPD: but there is no significant difference in the rate of haemorysis at 45°C and below.
Abstract: Incubation of blood in vitro for up to 1 hour at temperatures below 45°C caused no significant haemolysis as determined by a colorimetric method. The duration of storage of blood in CPD or ACD did not affect the sensitivity of the red cells to haemolysis at 50°C. Blood stored in ACD haemolyses less rapidly at 50°C than blood stored in CPD: but there is no significant difference in the rate of haemolysis at 45°C and below.
TL;DR: It would appear that neither method guarantees an empty stomach at induction and failure to induce vomiting with apomorphine does not signify that the stomach is empty.
Abstract: A comparison has been made between two methods of emptying the stomach before general anaesthesia in obstetric patients: aspiration by a stomach tube, and apomorphine-induced vomiting. It was found that most patients preferred apomorphine to the stomach tube. During the operation stomach contents were aspirated in both groups. The mean volumes aspirated were not significantly different. It would appear that neither method guarantees an empty stomach at induction and failure to induce vomiting with apomorphine does not signify that the stomach is empty. Patients, undergoing elective operations, starved for 6 hours and who were not subjected to either method of gastric emptying were found to have significant quantities of stomach contents during anaesthesia. There was no evidence that apomorphine had a deleterious effect on the Apgar scores of the infants at birth.
TL;DR: The authors showed that metoclopramide can almost completely eliminate the preoperative emetic effects of pethidine, and that an additional 10-20 mg at the end of the operation markedly reduced the emetic effect of pthidine premedication but has less effect when morphine has been given.
Abstract: When given with pethidine 100 mg or morphine 10 mg as preanaesthetic medication, 10 and 20 mg of metoclopramide cause a reduction in postoperative nausea and vomiting in women undergoing a standard operation with a standard anaesthetic technique. The preoperative emetic effects of pethidine are almost completely abolished by metoclopramide. An additional 10–20 mg of metoclopramide, given i.m. at the end of the operation markedly reduces the emetic effects of pethidine premedication but has less effect when morphine has been given. The evidence suggests that the ineffectiveness of metoclopramide, relative to other antiemetics, is because of its brevity of action.