Oxide-oxygen Anaesthesia Research Articles

EFFECT OF STIMULATION OF THE P6 ANTIEMETIC POINT ON POSTOPERATIVE NAUSEA AND VOMITING

The antiemetic action of stimulation of the P6 (Neiguan) acupuncture (ACP) point has been studied in women, premedicated with nalbuphine 10 mg, undergoing minor gynaecological operations under methohexitone-nitrous oxide-oxygen anaesthesia. Invasive ACP--manual or electrical at 10 Hz--applied for 5 min at the time of administration of the premedication markedly reduced the incidence of vomiting and nausea in the first 6 h after operation, compared with untreated controls. This did not occur with stimulation of a "dummy" ACP point outside the recognized ACP meridians. Non-invasive methods (stimulation via a conducting stud or by pressure) were equally as effective as invasive ACP during the early postoperative period. However, both these non-invasive approaches were less effective than invasive ACP in the 1-6 h postoperative period, although each was as effective as two standard antiemetics (cyclizine 50 mg, metoclopramide 10 mg). In view of the total absence of any side effects in more than 500 ACP procedures, the clinical applications of this finding are worthy of further study.

EFFECTS OF HALOTHANE ON MOTOR EVOKED POTENTIAL RECORDED IN THE EXTRADURAL SPACE

We studied the effects of supplementing nitrous oxide-oxygen anaesthesia with halothane (1 MAC end-tidal concentration) on the motor evoked potential recorded in the extradural space of eight patients before corrective surgery for idiopathic adolescent scoliosis. The motor cortex was stimulated electrically through the scalp. An additional eight patients in whom anaesthesia was supplemented with an infusion of propofol acted as a control group. Halothane had no significant effect on the amplitude or latency of the motor evoked potential. We conclude that halothane is unlikely to alter the interpretation of motor evoked potentials recorded extradurally during scoliosis surgery.

Rückkehr motorischer und mentaler Funktionen nach Enfluran-Stickoxidul-Narkose bei 1,3 MAC in verschiedenen Altersgruppen

Recovery of motor and mental functions we investigated in 60 patients at different age ranges (Group 1: 20 young patients between 20 and 35 years; Group 2: 20 middle-aged patients between 40 and 55 years; Group 3: 20 elderly patients between 60 and 73 years) after nitrous oxide-oxygen anaesthesia in combination with enflurane of 1.3 MAC for lumbar nucleotomy

SOMATOSENSORY-EVOKED POTENTIALS DURING BLOCK OF SURGICAL STIMULATION WITH PROPOFOL

The effect of propofol on somatosensory evoked potentials was assessed during different intra-operative stimuli in prolonged (greater than 2 h) abdominal operations. SSEP were used to evaluate the extent of block of sensory nerve conduction at the following stages: preinduction; during steady state anaesthesia; during traction of the mesentery; 10 min after anaesthesia. Propofol 100 micrograms kg-1 min-1 and nitrous oxide in oxygen anaesthesia induced a significant decrease in amplitude of the SSEP; noxious stimulation resulted in an increase in afferent nerve transmission and a concomitant increase of amplitude of the late evoked potential. After operation, impulse transmission recovered rapidly and the amplitude was similar to control at 10 min after anaesthesia.

Esmolol for Potentiation of Nitroprusside-Induced Hypotension

Esmolol infusion at rates of 200, 300, and 400 micrograms.kg-1.min-1 was used to potentiate hypotension (mean arterial pressure = 60 mm Hg) induced with sodium nitroprusside (SNP) in 10 male patients undergoing radical cancer surgery during nitrous oxide-oxygen and fentanyl anesthesia. Heart rate (HR), blood pressure (radial arterial catheter), and plasma levels of renin activity (PRA), norepinephrine (N), epinephrine (E), and dopamine (D) were measured: 1) while patients were awake; 2) after induction of anesthesia (nitrous oxide, 60% in oxygen, fentanyl = 5 micrograms/kg followed by an infusion at 10 micrograms.kg-1.hr-1); 3) after surgery had begun; 4) after 20 minutes of SNP-induced hypotension; 5) after 20 minutes of esmolol at each of the above infusion rates; and 6) after the completion of surgery. Compared to awake values, SNP-induced hypotension (mean infusion rate = 3.1 micrograms.kg-1.min-1 +/- 0.6 SE) during surgery resulted in significant (P less than 0.05) increases in heart rate, PRA, N, and D. Infusion of esmolol resulted in significant (P less than 0.05) dose-dependent reductions in SNP requirement to maintain MAP = 60 mm Hg. At 200 micrograms.kg-1.min-1, SNP requirement was 2.1 micrograms.kg-1.min-1 +/- 0.4, at 300 micrograms.kg-1.min-1, it was 1.0 micrograms.kg-1.min-1 +/- 0.2, and at 400 micrograms.kg-1.min-1, was 0.5 micrograms.kg-1.min-1 +/- 0.3. Concomitant with the decrease in SNP requirement, there were significant reductions in HR and PRA at all infusion rates of esmolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Sufentanil to supplement nitrous oxide in oxygen during balanced anaesthesia

Sufentanil in doses of 0.4 and 1.0 microgram/kg was used as an analgesic supplement to nitrous oxide-oxygen anaesthesia in 28 patients whose lungs were ventilated during body surface or lower abdominal surgery. Significant decreases in arterial blood pressure followed drug administration (mean 35.6%). Decreases in arterial pressure of greater than 30% occurred in 5 out of 14 patients in the low dose group, and 12 out of 14 in the high dose sufentanil group. There was a blunting of the pressor response to laryngoscopy and intubation after sufentanil. Increases in blood pressure were seen in both treatment groups at the onset of surgery. The peak responses were 27% increase in mean arterial pressure in the low dose group, and 51% increase in the 1.0 microgram/kg group. There was however no significant change in heart rate. Fourteen patients (8 in the low dose group) required volatile supplementation during surgery for clinical signs of inadequate anaesthesia. This occurred between 21 and 70 minutes after sufentanil administration, and plasma drug concentrations 0.06 and 0.54 ng/ml. Tracheal extubation was successfully achieved at the end of surgery in 26 out of 28 patients at plasma sufentanil concentrations which ranged from 0.03 to 0.37 ng/ml. The two remaining patients, neither of whom had received additional volatile supplementation, required naloxone to overcome postoperative ventilatory depression. No cases of intra-operative awareness were noted.

Clinical Pharmacology of Doxacurium Chloride (BW A938U) in Children

The neuromuscular effects of doxacurium were studied in 26 children during halothane-nitrous oxide-oxygen anesthesia. Neuromuscular blockade was measured using electromyographic activity of the adductor pollicis muscle after supramaximal stimulation of the ulnar nerve at 2 Hz for 2 seconds at 10-second intervals. To estimate the cumulative dose-response relation, nine patients received incremental doses of doxacurium (2.5-10 micrograms/kg); nine patients received 27.5 micrograms/kg (the estimated ED95); eight patients received 50 micrograms/kg (1.8 X ED95). The ED25, ED50, ED75, and ED95 (estimated from linear regression plots of log dose vs probit of effect) were 11.5, 14.8, 19.0, and 27.3 micrograms/kg, respectively. Clinical duration (T25) was 27.8 +/- 10.3 (mean +/- SD) minutes at 1 X ED95 and 50.6 +/- 15.6 minutes at 1.8 X ED95. Time to recovery of the train-of-four ratio to 0.75 was 63.1 +/- 32.9 minutes at 1 X ED95 and 108.5 +/- 25.7 minutes at 1.8 X ED95. There were no significant changes in heart rate or mean arterial pressure after bolus administration of any dose of doxacurium.

COMPARISON OF ATRACURIUM-INDUCED NEUROMUSCULAR BLOCKADE IN NEONATES, INFANTS AND CHILDREN

The potency of atracurium was determined in neonates, infants and children during thiopentone-fentanyl-nitrous oxide in oxygen anaesthesia using single dose-response curves. The effective doses producing 50% depression of the first twitch of the train-of-four were significantly lower in neonates and infants than in children (82 and 112 v. 135 micrograms kg-1). Following a standard dose of atracurium 0.5 mg kg-1, 95% depression of the first twitch occurred more rapidly in neonates than in children (0.9 v. 1.4 min), while recovery to 10% of the control twitch height occurred more rapidly in neonates than in the other two groups (22.7 v. 29.7 and 28.6 min). It is concluded that neonates and infants require less atracurium to produce a given degree of neuromuscular blockade compared with older children. However, prompt recovery can be expected in all healthy paediatric patients following a standard intubating dose of atracurium 0.5 mg kg-1.

Does the Choice of the Neuromuscular Blocking Agent Affect the Cardiovascular Response to Intubation?

Heart rate and arterial pressure changes induced by tracheal intubation, 3 min after administration of atracurium, vecuronium, tubocurarine, pancuronium or alcuronium, have been studied under thiopentonenitrous oxide-oxygen anaesthesia supplemented by either 0.5% halothane or fentanyl 2 micrograms kg-1. Pancuronium and alcuronium were associated with the greatest increase in heart rate and tubocurarine with the greatest decrease in arterial pressure prior to intubation. Following intubation, all groups, with the exception of tubocurarine showed a similar and significant rise in heart and arterial pressure when compared with control values. The cardiovascular response to intubation, particularly the effect on heart rate, was less marked when fentanyl was given at induction and was short lived with atracurium and vecuronium. Although those patients who received tubocurarine showed no significant rise in arterial pressure following tracheal intubation, this was due to significant hypotension occurring in this group prior to intubation.

FENTANYL AND THE β-ENDORPHIN, ACTH AND GLUCOREGULATORY HORMONAL RESPONSE TO SURGERY

The effect of the supplementation of nitrous oxide-oxygen anaesthesia with either fentanyl 15 micrograms kg-1 or 0.5% halothane on the beta-endorphin, ACTH, glucoregulatory hormonal and metabolic response to pelvic surgery was investigated. Fentanyl inhibited the increases in circulating beta-endorphin, ACTH, growth hormone, cortisol and glucose concentrations found in the patients receiving halothane. Changes in circulating beta-endorphin concentrations during surgery probably reflect alterations in pituitary secretion and appear to have no major metabolic effects. The suppression of pituitary secretion persisted for at least 4 h after the start of surgery.

AN EVALUATION OF THE ACCURACY OF PHARMACOKINETIC DATA FOR THE COMPUTER ASSISTED INFUSION OF ALFENTANIL

The accuracy of using average alfentanil pharmacokinetic data in a computer assisted infusion pump (TIAC) to predict alfentanil plasma concentrations was tested in 35 patients (divided into three groups) receiving alfentanil and nitrous oxide in oxygen anaesthesia for lower and upper abdominal surgery. By frequently measuring the arterial plasma concentration, it was possible to determine the average prediction error for individual patients and for groups of patients. For the groups, there were no significant systematic over- or underpredictions of the alfentanil plasma concentrations (bias). However, there existed a moderate degree of variability (imprecision) within the groups, caused by deviations of measured and predicted plasma concentrations in the individual patients within each group. As a result, prediction errors of 22.2-32.5% can be expected with the average pharmacokinetic data used in this study to drive TIAC. It was concluded that, as a result of the moderate degree of imprecision, it is unwise to rely totally on the absolute values of alfentanil plasma concentrations predicted by a computer-regulated infusion pump such as TIAC. However, such devices can be used to attain rapidly a relatively stable plasma concentration that can be adjusted (titrated) to the requirements of an individual patient during anaesthesia.

USE OF AN EMULSION OF ICI 35868 (PROPOFOL) FOR THE INDUCTION AND MAINTENANCE OF ANAESTHESIA

2,6-Diisopropyl phenol in a fat emulsion formulation (propofol) has been used to supplement 67% nitrous oxide in oxygen anaesthesia in 20 patients premedicated with morphine 0.15 mg kg-1 and atropine 0.6 mg, and undergoing body surface surgery. Following an induction dose of propofol 2.5 mg kg-1, the mean maintenance dose was 73.4 micrograms kg-1 min-1. When compared with 10 patients receiving Althesin to supplement nitrous oxide in oxygen in a similar manner, recovery was considerably faster following propofol. The only major side-effect associated with the use of propofol was pain on injection in nine out of 20 patients. When the patients receiving propofol were compared with a second control group (n = 11) in whom anaesthesia was induced with thiopentone 4 mg kg-1 and maintained with 1% halothane and nitrous oxide in oxygen, the former group showed a significant (P less than 0.01) decrease in the plasma cortisol concentration 30 min after the induction of anaesthesia. However, by 3 h after induction, the cortisol concentration in both groups was not significantly different from the baseline (preinduction) value. The mechanism of this decrease is not known. Investigation of the influence of the fat emulsion on blood coagulation and fibrinolysis revealed no differences when compared with patients receiving Althesin.

Antihypertensive activity and metabolic rate of prostaglandin E 1 in surgical patients under general anesthesia

Plasma immunoreactive prostaglandin E (iPGE) levels during PGE 1 infusion for controlling systemic blood pressure were investigated. Differences in systemic blood pressure changes between halothane-nitrous oxide-oxygen (GOF) anesthesia groups and a neuroleptanesthesia (NLA) group during infusion in hypertensive surgical patients were compared. Plasma iPGE concentration increased from 200 ± 30 pg/ml to 408 ± 55 pg/ml within 5 minutes at the beginning of PGE 1 infusion. After the cessation of PGE 1 infusion, iPGE levels quickly returned to pre-infusion levels, but blood pressure had not recovered to pre-infusion levels within 30 minutes. Blood pressure was well controlled with PGE 1 infusion, but the pressure changes in GOF anesthesia group were significantly larger than those in the NLA group. The results suggest that the long anti-hypertensive action of PGE 1 could be effective to control blood pressure in hypertensive surgical patients during and after surgery.

Common Bile Duct Pressure Changes After Fentanyl, Morphine, Meperidine, Butorphanol, and Naloxone

Five groups of 10 patients received thiamylal, enflurane, nitrous oxide-oxygen anesthesia for elective cholecystectomy. The common bile duct was intubated via the cystic duct with a 16-g plastic catheter, and the control intraductal pressure was measured. Patients then were given equi-analgesic doses of fentanyl, morphine, meperidine, butorphanol, or placebo intravenously, and the common bile duct pressure was recorded for 20 min. Fentanyl, morphine, and meperidine significantly increased pressure in the common duct (P less than 0.001). Butorphanol produced only insignificant changes. Naloxone given 20 min later significantly (P less than 0.001) decreased pressure in patients given fentanyl, morphine, and meperidine. Naloxone given without narcotics caused an increase in pressure that, although statistically significant (P less than 0.03), was clinically insignificant. In five additional patients anesthetized with thiamylal, nitrous oxide-oxygen and intermittent doses of fentanyl, common bile duct pressures were normal.

Antagonism of d-tubocurarine-induced neuromuscular blockade with a mixture of 4-aminopyridine and neostigmine in man.

The antagonistic properties of a mixture of 4-aminopyridine (4-AP) 3 mg X ml-1 and neostigmine 0.2 mg X ml-1 (in three patient groups) administered at 90 per cent d-tubocurarine block were compared with those of plain neostigmine (in three patient groups) in thirty-six patients during thiopentone-fentanyl-nitrous oxide-oxygen anaesthesia. The recovery variables included thumb twitch height, thenar e.m.g. peak-to-peak amplitude, and train-of-four ratio in response to supramaximal ulnar nerve stimulation. In addition, mean arterial pressure, heart rate, apnoea time and time to responsiveness to verbal command after nitrous oxide was turned off at 20 minutes of recovery were examined as circulatory and central nervous system responses to antagonism. The addition of 4-AP 30 mg to neostigmine 2 mg enhanced the recovery of train-of-four ratio from 54.2 +/- 5.2 to 80.2 +/- 5.2 per cent at 20 mins of antagonism (mean +/- SEM; p less than 0.01) while adding 4-AP 45 mg to neostigmine 3 mg increased the train-of-four ratio from 67.7 +/- 2.3 to 92.3 +/- 2.4 per cent (p less than 0.01) when compared with plain neostigmine. No statistically significant difference could be found between the groups in the recovery of twitch height or e.m.g. amplitude. The antagonism of d-tubocurarine block with 4-AP 30 mg plus neostigmine 2 mg was at least as effective as with neostigmine 3-4 mg. Mean arterial pressure increased in the group receiving 45 mg 4-AP plus 3 mg neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

MEASUREMENT OF THE RATES OF NITROUS OXIDE UPTAKE AND NITROGEN EXCRETION IN MAN

Using a completely closed anaesthetic circuit, nitrous oxide uptake and nitrogen excretion were measured simultaneously in patients undergoing nitrous oxide in oxygen anaesthesia for abdominal surgery. The results have been compared with standard models of uptake and excretion. Mean nitrous oxide uptake was measured and did not exceed 400 ml min-1 (normalized to 70-kg man) and was not less than 60 ml min-1 at 100 min after the start of nitrous oxide in oxygen anaesthesia. Nitrogen excretion did not exceed 100 ml min-1 and was measurable (8 ml min-1) at 100 min. The persistence of nitrogen excretion contrasts with other published data obtained with intact volunteers and this suggests that exposure at surgery of abdominal tissues, including fat, affects substantially the rates of excretion and uptake after 70 min.

BAROREFLEX EFFECTS OF ALTHESIN INFUSIONS TO SUPPLEMENT NITROUS OXIDE ANAESTHESIA IN MAN

The effects on baroreflex control of heart rate, of two infusion rates of Althesin (18 and 36 micrograms kg-1 min-1 as total steroid) to supplement 66% nitrous oxide in oxygen anaesthesia, have been studied in six younger (mean age 35.5 yr) and six older (mean age 61.0 yr) patients. Steady-state anaesthesia at both infusion rates was associated with diminished baroreflex sensitivity and resetting of the reflex to allow lower arterial pressures to be maintained without tachycardia.

HEPATIC FUNCTION AFTER ANAESTHESIA FOR MAJOR VASCULAR RECONSTRUCTIVE SURGERY: A comparison of four anaesthetic techniques

Three groups of patients received Althesin, minaxolone or di-isopropyl phenol to supplement 67% nitrous oxide in oxygen. A fourth group receiving halothane to supplement nitrous oxide in oxygen acted as a control. Hepatic function tests were measured before operation and on days 1, 3, 5 and 7 after major vascular reconstructive surgery. There were significant increases to a mean value above the upper limit of normal in aspartate amino-transferase activity by day 3 in all groups. Total lactic dehydrogenase activity increased in the patients receiving Althesin, minaxolone and halothane. No change was seen in the alkaline phosphatase in any of the study groups. Gamma glutamyl transpeptidase increased in all groups, but the mean value at day 7 was not greater than the upper limit of normal. The mean activity of ornithine carbamoyl transpeptidase showed no change in any group throughout the study period. Two of the patients receiving minaxolone suffered cholestatic jaundice during the first month. These results suggest that anaesthesia with Althesin or di-isopropyl phenol results in enzyme changes similar to those seen in a comparable group of patients receiving halothane to supplement nitrous oxide in oxygen anaesthesia.

Comparison of the cardiovascular effects of nitroglycerine and sodium nitroprusside during hypotensive anesthesia for clipping of cerebral aneurysm

The cardiovascular effects of nitroglycerine and sodium nitroprusside during hypotensive anesthesia were studied on 16 cases of cerebral aneurysm.Under halothane-nitrous oxide-oxygen anesthesia fully stabilized, nitroglycerine or sodium nitroprusside was administered by an infusion pump at the rate of 10μg/kg/min and 2μg/kg/min respectively.These rate were instantaneously adjusted to reduce the systolic blood pressure to 50-70mmHg.There were marked fall in arterial blood pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, central venous pressure, systemic vascular resistance and rate pressure product to the similar extent by hypotensive agents.Cardiac output revealed a tendancy to increase during hypotensive period.From these results authors concluded that both hypotensive agents reduce arterial blood pressure due to dilatation of peripheral vascular beds.Cardiac function indicated rather favorable condition during hypotensive period.

EFFECT OF HYPOCARBIA AND HYPERCARBIA ON THE ANTAGONISM OF PANCURONIUM-INDUCED NEUROMUSCULAR BLOCKADE WITH NEOSTIGMINE IN MAN

The effects of variations in carbon dioxide concentration on the antagonism of pancuronium-induced neuromuscular block by neostigmine were studied in 21 patients: normocarbia (PE'CO2 5.4%, PaCO2 4.93 kPa, n = 7), hypocarbia (PE'CO2 3.6%, PaCO2 3.30 kPa, n = 7) and hypercarbia (PE'CO2 7.5%, PaCO2 7.13 kPa, n = 7). Mechanical and electromyographic responses to ulnar nerve stimulation (0.1 Hz and 2 Hz) were recorded. A 90% block during nitrous oxide in oxygen anaesthesia was maintained by incremental single injections of pancuronium and reversed with neostigmine 0.35 mg kg-1 with atropine 0.0175 mg kg-1. The recovery of twitch tension up to 50% was similar in all groups but thereafter slower in the hypercarbia group. The recovery times from 25% to 75% twitch tension correlated with PaCO2 (r = 0.55, P less than 0.05). A residual block of about 10% was seen in hypercarbic patients. However, the recovery of e.m.g. amplitude and train-of-four ratios was similar in all groups. Thus, the impaired recovery of twitch tension seems to be the result of depressed contractility rather than failure of neuromuscular transmission.