Showing papers in "BJA: British Journal of Anaesthesia in 1977"
TL;DR: Intracranial pressure has been measured in 45 patients undergoing neurosurgery during the induction of deliberate hypotension using either sodium nitroprusside or trimetaphan and a statistically significant increase in ICP occurred during the early stages of the infusion of nitro Prusside in normocapnic patients.
Abstract: Intracranial pressure has been measured in 45 patients undergoing neurosurgery during the induction of deliberate hypotension using either sodium nitroprusside or trimetaphan. A statistically significant increase in intracranial pressure (ICP) occurred during the early stages of the infusion of nitroprusside in normocapnic patients. A non-significant increase in ICP was obtained in hypocapnic patients. The mean ICP increased from 6.3 mm Hg to 11.7 mm Hg when the arterial pressure was reduced slightly, but the response in individual patients varied widely (range -1.6 mm Hg to +20.9 mm Hg). When the arterial pressure (BP) had decreased to 70% of the value existing before infusion of nitroprusside, mean ICP returned to control values and thereafter decreased with further reductions in BP. In patients rendered hypotensive with trimetaphan, there was no change in mean ICP but two patients showed moderate increases (+9.3 mm Hg and +5.7 mm Hg). The mechanism of the increase in ICP with nitroprusside is thought to be expansion of the intracranial blood volume as a result of cerebral vasodilatation. Trimetaphan does not usually produce ICP changes except when intracranial compression is severe, for in these circumstances a small change in intracranial blood volume consequent upon autoregulation may trigger an increase in ICP.
124 citations
TL;DR: A new thebaine derivative, buprenorphine, 0.6 mg, was compared with morphine 15 mg in a double-blind trial, in patients recovering from elective Caesarean section, with no serious side-effects encountered.
Abstract: A new thebaine derivative, buprenorphine, 0.6 mg, was compared with morphine 15 mg in a double-blind trial, in patients recovering from elective Caesarean section. Within 1 h of administration analgesia was obtained with both drugs and was sustained for 7–8 h with buprenorphine, and 3–4 h with morphine. Buprenorphine caused a greater decrease in diastolic arterial pressure than did morphine, but arterial systolic pressure and heart rate were not influenced by either drug. No serious side-effects were encountered in this study.
104 citations
TL;DR: In six dogs chronically implanted with flow and pressure transducers, equipotent inspired concentrations of halothane and isoflurane were determined as the minimum inspried concentration of each agent which would abolish an individual dog's response to paw clamping.
Abstract: In six dogs chronically implanted with flow and pressure transducers, equipotent inspired concentrations of halothane and isoflurane were determined as the minimum inspired concentration of each agent which would abolish an individual dog's response to paw clamping. In equipotent concentrations, isoflurane (1.2%, SD 0.2%) caused less myocardial depression than halothane (1.0%, SD 0.1%). Dose–response studies were possible up to a mean inspired isoflurane concentration of 3.0%, both before and after propranolol 0.3 mg kg-1, i.v. After propranolol, sensitive indices of myocardial contractility were depressed at all concentrations of isoflurane, indicating a moderate degree of β-receptor activation by isoflurane. The hacmodynamic response to hypovolaemia during isoflurane anaesthesia was not modified by propranolol.
93 citations
TL;DR: The effects of local, i.v. and volatile anaesthetic agents on locomotion of human blood leucocytes were studied in vitro and it was concluded that Serum albumin can protect against the inhibitory action of anaesthetics.
Abstract: SUMMARY The effects of local, i.v. and volatile anaesthetic agents on locomotion of human blood leucocytes were studied in vitro. Blood neutrophils and monocytes and PHA-activated lymphocytes were allowed to migrate in filters towards standard chemotactic agents and the effect of adding anaesthetic agents to the system was measured. The results showed that locomotion of all cell types was depressed reversibly by all classes of anaesthetics used at clinical concentrations. The pattern of depression varied according to the cell type under study and the class of anaesthetic used. The action of anaesthetics on chemically stimulated locomotion of leucocytes was analysed. It was concluded that the principal action of these drugs is primarily on the mechanism of locomotion itself, rather than on the capacity of the cells to detect and respond to concentration gradients of attractants. Serum albumin can protect against the inhibitory action of anaesthetics.
92 citations
TL;DR: The effect of the inhalation of dried or humidified air was studied in dogs in which a tracheostomy had been performed and the optimal range of humidity was determined to be 100% water-saturation between 25 and 30 °C.
Abstract: The effect of the inhalation of dried (less than 40% water-saturation) or humidified air (100% water-saturation at 25, 30, 35 and 40 °C) was studied in dogs in which a tracheostomy had been performed to determine the optimal humidity. After inhalation for various periods, the dogs were killed and pieces of lung tissue were excised for analysis of surfactant. Sections of the trachea and the primary to tertiary bronchi were taken for scanning electron microscopic examination. Structural changes were observed in the trachea of dogs inhaling dried air and in the tertiary bronchi of dogs inhaling 100% water-saturated air at 35 °C. No change was observed after 24 h in dogs which had inhaled 100% water-saturated air at 25 °C under anaesthesia or at 30 °C without anaesthesia. Consequently, the optimal range of humidity was determined to be 100% water-saturation between 25 and 30 °C.
89 citations
TL;DR: The gastric contents of three groups of patients were aspirated at the beginning and end of anaesthesia and sodium citrate, as used in this study, was shown to be an ineffective antacid.
Abstract: The gastric contents of three groups of patients were aspirated at the beginning and end of anaesthesia. There were 62 prepared patients, 28 emergency patients untreated and 69 prepared patients who were given 15 ml of 0.3 M sodium citrate mixture at the time of premedication. In approximately 50% of both emergency and prepared patients pH of gastric contents initially suggested the risk of developing acid aspiration syndrome, had inhalation occured. The proportion of untreated patients in whom more than 40 ml of gastric contents was present at induction and when the tracheal tube was removed were 13% and 31% respectively. The risks were greater in those undergoing upper abdominal operations. Sodium citrate, as used in this study, was shown to be an ineffective antacid. The use of Mist. magnesium trisilicate B.P. as preoperative antacid is urged strongly.
83 citations
TL;DR: It may be clinically significant that hypoxia and hypercapnia during anaesthesia with these agents did not produce optimal stimulation of ventilation.
Abstract: The ventilatory responses to isocapnic hypoxia and hypercapnia were studied in six dogs each with a tracheostomy, awake and during anaesthesia with halothane, enflurane and isoflurane (1-2.5 MAC). Isocapnic hypoxic ventilatory response (HVR) was expressed as the parameter A, such that the greater the value of A, the greater the hypoxic response. In the anaesthetized dogs HVR (A) was reduced significantly from the awake value of 2010 +/- 172 (mean + SEM) to 630 +/- 173 by 1 MAC halothane, 495 +/- 105 by 1 MAC enflurane and 952 +/- 157 by 1 MAC isoflurane (PL0.05). All three anaesthetic agents produced significant depression of HUR at 1 MAC, but enflurane was more depressant than isoflurane. At 1.5 MAC all three anaesthetics produced equal and significant depression of HVR at equianalgesic concentrations. Further increases in anaesthetic concentration caused no increase in depression. Hypercapnic drive, as measured by the slope of the VE/PACO2 response curve, was reduced significantly from 9.75 litre min-1 kPa-1 +/- 2.4 in awake dogs to 0.83 +/- 0.56 after 1 MAC halothane, 0.68 +/- 0.53 after 1 MAC enflurane and 1.58 +/- 0.75 after 1 MAC isoflurane. In addition, hypercapnia-induced augmentation of the hypoxic drive was abolished by 1 MAC halothane or enflurane and diminished markedly by 1 MAC isoflurane. It may be clinically significant that hypoxia and hypercapnia during anaesthesia with these agents did not produce optimal stimulation of ventilation.
83 citations
TL;DR: By injecting a mixture of a radio-opaque substance and 4% lignocaine it was shown by comparison of the radiological spread of the solution and the distribution of clinical analgesia that the latter always exceeded the former by four to six segments, indicating the occurrence of diffusion.
Abstract: Data on the segmental spread of analgesia from three independent studies of caudal extradural blocks in children with three different local anaesthetic agents were examined with multiple regression techniques to find the effects of age on dose requirements. All three studies confirmed the existence of a linear relationship between the spread of analgesia and age. As there were no significant differences between the three regression lines a common regression line was calculated. This may be used as a guideline for predicting dose requirements in the daily routine of anaesthesia. By injecting a mixture of a radio–opaque substance and 4% lignocaine it was shown by comparison of the radiological spread of the solution and the distribution of clinical analgesia that the latter always exceeded the former by four to six segments. This may indicate the occurrence of diffusion.
77 citations
TL;DR: Comparison of the results revealed that the major factor responsible for reduction of operative mortality to almost zero was control of hypotension by replacement of blood volume rather than by the use of noradrenaline following resection of the tumour.
Abstract: A total of 102 patients with phaeochromocytoma who underwent surgery by the same team between 1964 and 1976 were allocated to three groups according to the anaesthetic protocol used: (1) balanced anaesthesia and control of hypotension with noradrenaline; (2) anaesthesia with halothane and replacement of blood volume; (3) neuroleptanalgesia (droperidol and phenoperidine) and replacement of blood volume. None of the patients in any of the three groups received adrenergic inhibitors before anaesthesia. Comparison of the results in the three groups revealed that the major factor responsible for reduction of operative mortality to almost zero was control of hypotension by replacement of blood volume rather than by the use of noradrenaline following resection of the tumour, whereas the type of anaesthetic agent used was of secondary importance.
76 citations
TL;DR: Glycopyrrolate 0.2 mg to neostigmine 1.0 mg was found to be safe and effective and the antisialogogue action of glycopyrolate was superior to that of atropine.
Abstract: Glycopyrrolate, a new anticholinergic agent, was evaluated and compared with atropine. Glycopyrrolate 0.2 mg to neostigmine 1.0 mg was found to be safe and effective. The heart rates remained more stable with glycopyrrolate, and the frequency of arrhythmia, which was both transient and of no consequence, was similar in the two groups. The antisialogogue action of glycopyrrolate was superior to that of atropine.
72 citations
TL;DR: Plasma concentrations of local anaesthetic agents have been measured after 40 interscalene brachial plexus blocks in 39 patients, using lignocaine, prilocaine and bupivacaine, and the addition of adrenaline resulted in much lower concentrations in the case of all four agents.
Abstract: Plasma concentrations of local anaesthetic agents have been measured after 40 interscalene brachial plexus blocks in 39 patients, using lignocaine, prilocaine, bupivacaine and etidocaine. Lignocaine produced greater concentrations than prilocaine, and bupivacaine greater concentrations than etidocaine. The addition of adrenaline resulted in much lower concentrations in the case of all four agents.
TL;DR: With improving standards of antenatal care, severe pre-eclampsia dn eClampsia are becoming less common and experience in the management of these conditions is lessening, so co-ordinated plans for the care of patients should be established by obstetricians and anaesthetists working as a team.
Abstract: With improving standards of antenatal care, severe pre-eclampsia dn eclampsia are becoming less common and experience in the management of these conditions is lessening Co-ordinated plans for the care of patients should be established by obstetricians and anaesthetists working as a team A suitable regime for drug therapy in severe pre-eclampsia or eclampsia is the following: Initial management Diazepam 10 mg slowly iv Pethidine 100-150 mg im or iv in incremental dosage, or extradural blocks, if analgesia is also required Hydrallazine 20 mg iv initially, followed by 5 mg at intervals of 20 min until the diastolic pressure is less than 110 mm Hg Then, preferably by syringe pump in a concentration of 2 mg/ml, at a rate of 2-20 mg/h If vomiting occurs this can be controlled by administration of atropine Subsequent management Sedation and anticonvulsant therapy Continue diazepam and, in severe cases, institute chlormethiazole infusion Continue analgesia with pethidine or extradural block Control of hypertension by adjusting the dose of hydrallazine If tachycardia exceeds 120 beat/min give propanolol 2-4 mg iv Plasma protein depletion with groww oedema is treated by administration of salt-free albumin or plasma protein fraction Diuretic therapy is indicated if there is gross oedema or signs suggestive of acute renal failure Oliguria associated with increased blood urea may be a result of renal failure or dehydration The latter should be evident from the patient's condition and central venous pressure, but iv fluids and frusemide 20-40 mg can be used as a therapeutic test Mannitol reduces cerebral oedema and may be given if diuresis has been first produced with frusemide Potassium chloride is given if the plasma potassium decreases to less than 3 mmol/litre Heparin therapy is considered if there is clinical evidence of disseminated intravascular coagulation
TL;DR: Plasma concentrations of pancuronium were measured in nine patients undergoing surgery because of total biliary obstruction and the terminal half-life of 270 min was more than twice normal.
Abstract: Plasma concentrations of pancuronium were measured in nine patients undergoing surgery because of total biliary obstruction. When compared with the averaged model-independent pharmacokinetic parameters obtained for normal patients, the terminal half-life of 270 min was more than twice normal (132 min, P
TL;DR: It would appear that the effects of etomidate on respiration are less than those of other i.v. induction agents, but involuntary muscle movement during induction remains a problem.
Abstract: The respiratory effects of etomidate 0.3 mg/kg were studied in patients premedicated with either diazepam and atropine or papaveretum and hyoscine. The incidence of apnoea was 40% in those who received the non-narcotic premedication, compared with 27% in those who received the opiate. Those premedicated with diazepam and atropine showed a significant increase in respiratory frequency which was associated with a significant increase in minute volume 4 min after induction of anaesthesia. No such increase occurred in those premedicated with papaveretum and hyoscine. It would appear that the effects of etomidate on respiration are less than those of other i.v. induction agents, but involuntary muscle movement during induction remains a problem.
TL;DR: In seven patients who suffered anaphylactic cardiovascular collapse during anaesthesia the degree of haemoconcentration was used to assess changes in blood volume, suggesting plasma loss of 20.2-37%.
Abstract: In seven patients who suffered anaphylactic cardiovascular collapse during anaesthesia the degree of haemoconcentration was used to assess changes in blood volume. The patients who were resuscitated with electrolyte solutions, or electrolyte solutions with a small volume of colloid, showed haemoconcentration suggesting plasma loss of 20.2–37%. Patients who were resuscitated initially with colloid solutions showed minimal haemoconcentration. In anaphylactic cardiovascular collapse, the reduction of blood volume is a result of loss of plasma and colloid solutions should be used to replace the volume deficit.
TL;DR: It is suggested that a reduction in the lifetime of open postsynaptic ionic channels is a common action of anaesthetic drugs and a similar effect at central synapses may account for a failure of synaptic transmission caused by anaesthesia drugs.
Abstract: The effects of sodium thiopentone 19–757μmol/litre, sodium pentobarbitone 25–806 μmol/litre, propanidid 74–1186 μol/litre, Althesin 55–220 μol/litre, diazepam 17.6–140 μmol/litre and ketamine 1.8–116.8 μmol/litre on the time–course of miniature end–plate currents of the excised mouse diaphragm were investigated. The currents were detected by means of extracellular electrodes and recorded with a transient recorder. The drugs had no significant effect on the growth phase of the current, but all six shortened the time-constant of the decay phase. This reduction in the duration of end-plate currents reduced the amplitude of postsynaptic potentials. A similar effect at central synapses may account for a failure of synaptic transmission caused by anaesthetic drugs and it is suggested that a reduction in the lifetime of open postsynaptic ionic channels is a common action of anaesthetic drugs.
TL;DR: In six patients undergoing coronary vein graft operations under cardiopulmonary bypass and hypothermia, the temperatures of arterial and mixed-venous blood, nosopharynx, oesophagus, liver, rectum, deltoid and vastus lateralis muscles and 10 skin sites were recorded.
Abstract: In six patients undergoing coronary vein graft operations under cardiopulmonary bypass and hypothermia, the temperatures of arterial and mixed-venous blood, nasopharynx, oesophagus, liver, rectum, deltoid and vastus lateralis muscles and 10 skin sites were recorded. Whole-body oxygen consumption was measured before cooling and twice during hypothermia. On average, a patient lost 1000 kJ of heat by the end of hypothermia, of which 84% was lost to the heat-exchanger and pump circuit. Evaporative and convective loss amounted to 380 kJ, while the patient's metabolism supplied 220 kJ. During rewarming, the pump returned 670 kJ to the patient. Nasopharyngeal temperature reflected accurately venous, oesophageal and hepatic temperatures in the steady state; however, it was slow to reflect changes. Compared with other sites, muscle remains warmer during hypothermia and cooler after rewarming.
TL;DR: Progressive visual reaction times were measured before and after exposure of 10 subjects (anaesthetics or anaesthetic technicians) to either halothane 100-150 p.p.m. in air or air alone and there were no significant differences between the control and test situations.
Abstract: Progressive visual reaction times were measured before and after exposure of 10 subjects (anaesthetists or anaesthetic technicians) to either halothane 100–150 p.p.m. in air or air alone. There were no significant differences between the control and test situations. In a subsequent study of 15 psychology students using an audiovisual reaction time test, a tachistoscope and the Wechsler memory scale, there was no significant difference in the subjects' responses when breathing either air or a mixture of halothane 15 p.p.m. and nitrous oxide 500 p.p.m. in air (range: halothane 10.3–16.0 p.p.m., nitrous oxide 485–700p.p.m.).
TL;DR: To produce a blood-free field for middle ear surgery performed with the operating microscope, the arterial systolic pressure was reduced to less than 50 mm Hg in 700 patients by means of thiopentone-halothane-nitrous oxide in oxygen anaesthesia together with pentolinium tartrate.
Abstract: To produce a blood-free field for middle ear surgery performed with the operating microscope, the arterial systolic pressure was reduced to less than 50 mm Hg in 700 patients by means of thiopentone-halothane-nitrous oxide in oxygen anaesthesia together with pentolinium tartrate. In 84% the results were excellent, in 12% moderately good and they were poor in 4%. There were more unsatisfactory results in males (22.8%) than in females (11.4%). In spite of the arterial pressure being reduced to very low values in many instances, there was no mortality or morbidity which could be ascribed to the technique.
TL;DR: Buprenorphine 4-8 microgram-kg-1 was shown to be an effective analgesic, superior in some cases to the other drugs in the doses employed in the study.
Abstract: The analgesic effects of buprenorphine 2 μg.kg−1, 4 μg.kg−1 and 8μg.kg−1 were compared with those of pethidine 1 mg.kg−1 and pentazocine 0.6 mg.kg−1 in 172 patients recovering from surgery. The drugs were given by i.m. injection in the period immediately after operation and the quality of pain relief was assessed at intervals for at least 4 h. Buprenorphine 4–8 μg.kg−1 was shown to be an effective analgesic, superior in some cases to the other drugs in the doses employed in the study.
TL;DR: Venting and inspired gas composition were made while volunteers breathed a non-anaesthetic gas through a Bain anaesthetic system and it was found that rebreathing occurred when the fresh gas flow was between two-and-a-half and three times the minute volume.
Abstract: Measurements of ventilation and of inspired gas composition were made while volunteers breathed a non-anaesthetic gas through a Bain anaesthetic system. It was found that rebreathing occurred when the fresh gas flow was between two-and-a-half and three times the minute volume. Fresh gas flows at least three times the minute volume appear to be necessary to prevent rebreathing when using this system.
TL;DR: Oral lorazepam in doses of 2.5-5.0 mg was a reliable, effective sedative which could be recommended for routine preanaesthetic medication, provided rapid recovery was not essential.
Abstract: Lorazepam has been studied as preanaesthetic medication given by mouth, i.m. and i.v. Sedation and side-effects and the incidence of anterograde amnesia in patients having a standard operation under methohexitone-nitrous oxide-oxygen anaesthesia were assessed. In a preliminary study of three i.m. (2-, 4- and 8-mg) and six oral (1-, 2-, 2.5-, 4-, 5- and 8-mg) doses, the optimum dose was found to be 4 mg for patients with an average weight of 60 kg. This dose was studied in detail when given by all three routes and compared with the commercially available 2.5-and 5-mg tablets. Even when given i.v., there was a delay of 30—40 min in the onset of maximum sedative effect and drowsiness persisted for at least 4 h. Although the onset of action by i.m. injection was slightly faster than when the drug was given by mouth this advantage was more than offset by the high frequencies of pain at the site of injection and restlessness which persisted for 20—40 min. Oral lorazepam in doses of 2.5—5.0 mg was a reliable, effective sedative which could be recommended for routine preanaesthetic medication, provided rapid recovery was not essential. Its soporific effect was accompanied by an appreciable incidence of anterograde amnesia.
TL;DR: The results demonstrate the importance of alpha-adrenergic stimulation to heat production in MH-susceptible pigs and show the effects of noradrenaline alone on lipolytic response and hyperglycaemic response.
Abstract: The effects of the administration of noradrenaline alone, and noradrenaline with either phentolamine or propranolol, on thermogenesis and substrate mobilization were investigated in six Pietrain (MH-susceptible) and six Large White (unsusceptible) pigs. The infusion of noradrenaline alone produced a significantly increased lipolytic response and a significantly decreased hyperglycaemic response in Pietrain pigs compared with the Large White breed. Although noradrenaline alone produced only a small increase in body temperature in both breeds, the administration of noradrenaline with propranolol in two Pictrain pigs was associated with the development of fatal hyperthermia. In a further experiment, phenylephrine or isoprenaline was infused into six Pietrain pigs. Three pigs, receiving phenylephrine, became hyperthermic and died, whereas isoprenaline had no effect on body temperature. The results demonstrate the importance of α-adrenergic stimulation to heat production in MH-susceptible pigs.
TL;DR: The most favourable flow waveform for most variables was the reversed ramp waveform which resulted in decreased V D/ V T and P a CO2 , and increased P a O2, and total dynamic and lung compliance, when compared with the Ramp waveform.
Abstract: In artificial ventilation with alteration in inspiratory flow waveforms and time, there were statistically significant differences in a number of physiological variables. Tidal volume and respiratory frequency were kept constant and inspiratory time and waveform both varied independently. With shortening of inspiratory time physiological deadspace to tidal volume ratio (VD/VT) increased, total dynamic and lung compliance decreased, PaO2, decreased, PaCO2 increased and mean airway and oesophageal pressures decreased. There was no change in alveolar to arterial PO2 difference (PAO2–PaO2), in cardiac output, or in chest wall compliance. The most favourable flow waveform for most variables was the reversed ramp waveform which resulted in decreased VD/VT and PaCO2, and increased PaO2, and total dynamic and lung compliance, when compared with the ramp waveform. The effects of sine and top-hat waveforms could not be separated statistically but were significantly different from ramp and reversed ramp waveforms, having effects between these two. The reversed ramp waveform produced the greatest mean airway and oesophageal pressures, and the ramp waveform the least. No differences were found for chest wall compliance and (PAO2–PaO2) and the cardiac output changes were equivocal (but with the suggestion of waveform effects with ramp waveform allowing the best output and reversed ramp and top-hat waveforms the poorest). Pulmonary venous admixture increased with shortening of inspiratory time, and ramp flow waveform, and decreased with the reversed ramp flow waveform.
TL;DR: A 9-year-old boy undergoing anaesthesia including suxamethonium and halothane suffered cardiac arrest on two occasions and clinical and laboratory examination showed that the patient had suffered from acute rhabdomyolysis.
Abstract: A 9-year-old boy undergoing anaesthesia including suxamethonium and halothane suffered cardiac arrest on two occasions. Clinical and laboratory examination subsequently showed that the patient had suffered from acute rhabdomyolysis. The eventual recovery was satisfactory.
TL;DR: It is suggested that screening for malignant hyperpyrexia by in vitro pharmacological testing of skeletal muscle should be carried out at 37 degrees C, and should include exposure of the sample to halothane, caffeine, suxamethonium and potassium rather than to Halothane alone.
Abstract: Skeletal muscle from normal human subjects produced linear contracture responses in vitro to caffeine at concentrations of between 4 and 32 mmol/litre. In the presence of 0.4% halothane, caffeine contractures were greater but the magnitude of halothane potentiation decreased as the caffeine concentration was increased. The contractures produced by caffeine 4 and 8 mmol/litre at 37 degrees C were significantly reduced by decreasing the temperature of the incubation solution to 25 degrees C. Among 57 normal subjects, 18% had fibres which responded to halothane treatment with contracture. On the basis of these findings, it is suggested that screening for malignant hyperpyrexia by in vitro pharmacological testing of skeletal muscle should be carried out at 37 degrees C, and should include exposure of the sample to halothane, caffeine, suxamethonium and potassium rather than to halothane alone.
TL;DR: Halothane with and without nitrous oxide and chloroform alone were tested for mutagenic effects at the 8-azaguanine locus on the chromosomes of Chinese hamster lung fibroblast cells in culture.
Abstract: Halothane with and without nitrous oxide and chloroform alone were tested for mutagenic effects at the 8-azaguanine locus on the chromosomes of Chinese hamster lung fibroblast cells in culture. No significant numbers of mutations were found after 24 h exposures to 1–3% of these anaesthetics, or to 75%.nitrous oxide.
TL;DR: The data suggest that the antagonism of narcotics with high doses of naloxone may impair the myocardial oxygen supply in patients suffering from coronary insufficiency.
Abstract: The cardiovascular effects of naloxone 15 μg/kg following morphine 2.0 mg/kg were studied in closed-chest dogs during light nitrous oxide-halothane anaesthesia. The bolus injection of naloxone caused an increase in heart rate (73%), cardiac output (20%) and mean arterial pressure (20%). Total peripheral resistance was unaffected. LV d P 0/dt max and LV d P /dt max/IP increased by 25% and 14% respectively, but positive inotropic effects could not be shown when load data, heart rate and the decrease in left ventricular ejection fraction (22%) were taken into consideration. The cardiovascular stimulation resulted in an increase in myocardial oxygen demand (66%) which was met by an increase in coronary blood flow (59%). The data suggest that the antagonism of narcotics with high doses of naloxone may impair the myocardial oxygen supply in patients suffering from coronary insufficiency. It is concluded that naloxone should be titrated for each patient to ensure adequate reversal of respiratory depression and to avoid circulatory stress.
TL;DR: In seven normal subjects premedicated with atropine and pethidine and lightly anesthetized with thiopentone, the ventilatory response evoked by doxapram 20 mg i.v. is consistent with drug activity on both peripheral and central respiratory control mechanisms.
Abstract: In seven normal subjects premedicated with atropine and pethidine and lightly anaesthetized with thiopentone, the ventilatory response evoked by doxapram 20 mg i.v. was delayed on average from 15.7 s to 23.0 s when changing from air to oxygen breathing. Mean VE, immediately after the administration of doxapram was increased by 3.3 litre and 1.9 litre when breathing air and oxygen respectively. These findings indicate that doxapram has an effect on the peripheral chemoreceptors and are consistent with drug activity on both peripheral and central respiratory control mechanisms.
TL;DR: It is found that the neonate can metabolize pethidine, although the rate of metabolism is probably less than in the adult.
Abstract: In seven neonates, whose mothers were given pethidine during labour, urine was collected for the first 24–40 h of life. Urinary volume and pH, and concentrations of pethidine and norpethidine in the urine were measured. Urine flow rate was low for the first 7–22 h, and then high for about 12 h. The rate of excretion of pethidine and norpethidine was approximately parallel to the urine flow rate. However, the ratio of the rate of excretion of norpethidine to that of pethidine increased with time and the concentration of norpethidine in urine decreased first and then, after 18 h, increased significantly. These findings indicate that the neonate can metabolize pethidine, although the rate of metabolism is probably less than in the adult. The total amounts of pethidine and norpethidine excreted in the first 24 h after birth were positively related to the does-delivery interval in the mother for intervals up to at least 5 h. From the data it is estimated that 95% of the total pethidine transferred from the mother would be eliminated by the baby by the 2nd to 3rd day after birth.