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Biomedical subjects

C S Reilly

Publications and source records attributed to C S Reilly.

At least 55 records · Page 3Linked to original sources

Infusion of propofol to identify smallest effective doses for induction of anaesthesia in young and elderly patients.

We studied 110 patients older than 60 yr or aged 18-50 yr as separate groups in two stages to identify the smallest effective doses of propofol for induction of anaesthesia. In the elderly patients, in stage 1, at infusion rates of 25, 50 or 100 mg min-1 the mean (SD) doses administered were propofol 0.82 (0.14) mg kg-1, 1.22 (0.24) mg kg-1 and 1.65 (0.60) mg kg-1 and the induction times 140.1 (21.9) s, 103.2 (23.5) s and 69.4 (10.0) s, respectively. In stage 2, after induction with a fixed dose of 0.82 mg kg-1 as a bolus over 5 s or as an infusion at 25 mg min-1, the times for induction were 38.5 (14.0) s and 144.5 (36.6) s, respectively. In the young patients, at induction rates of 33.3, 50, 100 or 200 mg min-1, the doses administered were propofol 1.36 (0.28) mg kg-1, 1.46 (0.12) mg kg-1, 1.85 (0.43) mg kg-1 and 2.39 (0.50) mg kg-1 and the induction times 145.0 (25.4) s, 120.0 (18.4) s, 80.2 (19.2) s and 54.5 (10.4) s, respectively. In stage 2, a fixed induction dose of 1.46 mg kg-1 resulted in induction times of 35.0 (8.5) s and 134.0 (26.8) s, respectively. In stage 2 of each age group, induction was achieved with smaller doses than those recommended previously and there was no difference in the number of patients in whom induction of anaesthesia was successful or in the measured cardiorespiratory variables between the two induction regimens. This suggests the latter effects are caused by the dose administered and not the rate of administration.

Adolescent↗

Disposition of alfentanil in burns patients.

We have studied the disposition of alfentanil in six patients (who had suffered 10-30% surface area burns 5-21 days previously) undergoing surgical debridement and grafting and compared the data with those from a control group of six patients matched for age, sex and weight undergoing body surface surgery of similar duration. Plasma samples were collected up to 480 min after an i.v. bolus of alfentanil 50 micrograms kg-1. Drug concentrations were measured by radioimmunoassay and alfentanil binding to plasma proteins by equilibrium dialysis. The burns patients had significantly greater concentrations of alpha-1-acid glycoprotein (AAG) and smaller concentrations of albumin. The mean protein binding of alfentanil was 94.2 (SEM 0.05)% in the burns group and 90.7 (0.4)% in the control group (P = 0.004). There was a good correlation between AAG concentration and protein binding (r = 0.8). The volume of distribution and total clearance of alfentanil were reduced significantly in the burns group. The clearance of the unbound fraction and the elimination half-life of alfentanil were not decreased significantly.

Adolescent↗

Pharmacokinetics of lignocaine in children after infiltration for cleft palate surgery.

We have studied the pharmacokinetics of lignocaine in children after local infiltration for cleft palate surgery. After induction of anaesthesia, lignocaine 2.5 mg kg-1 with adrenaline 1:200,000 was injected into the palate. Blood samples were collected before and at 2, 5, 10, 15, 20, 30, 60 and 120 min after infiltration. Plasma concentrations of lignocaine were measured by a gas-liquid chromatographic technique. There were no signs of systemic toxicity on routine monitoring of the patients and the peak plasma concentrations were less than the accepted toxic values. Mean half-life was 72.9 (SEM 9.9) min, similar to that found previously in adults and children. However differences in mean clearance (24.6 (2.04) ml kg-1 min-1) and volume of distribution (0.80 (0.07) litre kg-1) were found between this and previous studies.

Anesthesia, General↗

The response times during anaesthesia of pulse oximeters measuring oxygen saturations during hypoxaemic events.

Episodes of desaturation were recorded simultaneously by computer from two Ohmeda Biox 3700 pulse oximeters, one with an ear and one with a finger probe, on patients undergoing anaesthesia. Over a period of 6 months, 28 episodes of desaturation were detected. Analysis of the recordings showed the mean minimum saturations recorded for ear and finger probes were 86.3% and 83.5% respectively (p less than 0.01). The mean delay for finger compared to ear pulse oximetry was 4.4 s (p less than 0.01). Analysis at different saturation levels showed finger probe responses to be significantly slower than ear probe responses at saturations equal to and above 91% (p less than 0.05). At saturation levels of 90% or less no significant difference in probe response times were found.

Adult↗

Maintenance of anaesthesia with propofol--a comparative study of a stepdown infusion of propofol and a low dose infusion supplemented by incremental doses.

Forty-four patients, ASA Grade I or II, had anaesthesia induced with propofol at 100 mg min-1 followed by a maintenance rate of 6 mg kg-1 h-1 or a stepdown regimen of 10 mg kg-1 h-1 for 10 min, 8 mg kg-1 h-1 for the next 10 min and at 6 mg kg-1 h-1 thereafter. Anaesthesia was maintained with propofol infused using an Ohmeda 9000 pump supplemented by nitrous oxide and oxygen (2:1) in a Bain circuit with spontaneous ventilation. Incremental doses of 20 mg of propofol were given to both groups as clinically indicated to maintain anaesthesia. Both methods provided satisfactory maintenance of anaesthesia but significantly more incremental doses were required in the group receiving the steady rate infusion. However, a lower cumulative dose was required up to 30 min in this group but not by 40 min. A comparable fall in systolic and diastolic blood pressure and heart rate was seen in both groups. There was no difference in the recovery times between the groups and the total dose did not correlate with time to recovery.

Adult↗

Continuous ambulatory ECG monitoring in the perioperative period: relationship of preoperative status and outcome.

We have used continuous ambulatory electrocardiography in the perioperative period to monitor 108 patients with known cardiovascular disease undergoing non-cardiac surgery. There was a high incidence of ischaemic ST segment changes and ventricular arrhythmias. For the group as a whole, anaesthesia and surgery were followed by increased ventricular ectopic activity, but did not worsen myocardial ischaemia. However, the mean duration of ischaemic ST segment changes was increased significantly in those patients with treated hypertension. Of the risk factors considered, preoperative ischaemia and peroperative systolic arterial pressure were significant correlates with postoperative myocardial ischaemia.

Aged↗

Gastric emptying in pregnancy.

The rate of gastric emptying in pregnancy was measured indirectly using the rate of paracetamol absorption in four groups of 15 patients: non-pregnant controls, first trimester patients presenting for termination of pregnancy, second trimester patients presenting for prostaglandin termination of pregnancy, and patients presenting for elective Caesarean section. All patients were fasted for 6 h and then received paracetamol tablets 1.5 g orally with water 50 ml. Blood samples were taken at 15-min intervals for 120 min and analysed for paracetamol concentration. There was no significant difference between the groups in the maximum concentration and time to maximum concentration (ANOVA). The AUC was reduced for the first trimester group at 60 and 120 min (P less than 0.05). No significant delay in gastric emptying was demonstrated in any of the three trimesters of pregnancy compared with the control group.

Acetaminophen↗

Effectiveness of preoxygenation in morbidly obese patients.

The time taken for the oxygen saturation (SpO2) to decrease to 90% after preoxygenation was studied in six morbidly obese patients and six matched controls of normal weight. During apnoea the obese patients maintained Spo2 greater than 90% for 196 (SD 80) s (range 55-208 s), compared with 595 (SD 142) s (range 430-825 s) in the control group (P less than 0.001). One patient in the obese group had desaturation before the onset of complete relaxation and tracheal intubation, without complications. Bedside lung function tests were not significantly different between groups and cannot be used as a predictor of the effectiveness of preoxygenation.

Carbon Dioxide↗

Policies for oral intake during labour. A survey of maternity units in England and Wales.

A postal survey was conducted to gain information on the use of policies on oral intake, selection of mothers and type of intake given during established labour by all maternity units in England and Wales. A response rate of 91.6% (351 out of 383) was achieved; 79.5% of units had a written policy for oral intake, 96.4% of units allowed mothers some form of oral intake and 68.3% of these units selected mothers according to risk categories. Of the 268 units allowing oral intake, 67.2% gave drink only and 32.8% drink and food. Of those allowing food, all but 13.6% had a selection policy. Of the 85 units not selecting mothers, 78.8% gave water only; the remaining 21.2% gave water and other drink or food. This survey demonstrates a wide variation in policies for oral intake during labour.

Anesthesia, Obstetrical↗

Paracetamol metabolism after general anaesthesia.

Paracetamol metabolism was compared between nine patients after general anaesthesia and nine healthy volunteers. Each subject received 1.5 g of paracetamol orally, and paracetamol concentrations in venous blood were measured by HPLC at intervals over 12 h. Urine samples collected over 24 h were analysed by HPLC for cysteine, mercapturic acid, sulphate and glucuronide metabolites. There were no significant differences in the area under the concentration-time curve for paracetamol, or plasma half-life. Statistically significant differences were observed in the median percentages of unchanged paracetamol (volunteers 2.9%, patients 2.0%) and mercapturic acid (volunteers 4.5%, patients 6.5%) excreted in 24 h. The percentage of sulphate excreted was significantly lower in the 8-24-h period, although there was no difference over the total 24 h.

Acetaminophen↗

A survey of general anaesthesia and sedation in dental practice in two cities.

Using a postal questionnaire, the use of general anaesthesia and sedation in general dental practice in two cities over a 4-week period was investigated. Questionnaires were sent to a random sample of one in five dental practitioners in Bristol and Sheffield, and an 82% response rate was attained. More practices in Sheffield administered general anaesthesia than those in Bristol. The differences between the facilities provided are discussed. Equipment and facilities have improved since a larger survey was described in 1976, but the use and availability of monitoring equipment has changed little since then. The results reflect the decline in the use of general anaesthesia in dental practice seen nationally. The survey provides an insight into the current anaesthetic services provided in general dental practice in two cities, both of which contain dental hospitals, and provides a basis for the design of a protocol for a further national survey.

Anesthesia Recovery Period↗

Effect of different rates of infusion of propofol for induction of anaesthesia in elderly patients.

The effect of changing the rate of infusion of propofol for induction of anaesthesia was studied in 60 elderly patients. Propofol was administered at 300, 600 or 1200 ml h-1 until loss of consciousness (as judged by loss of verbal contact with the patient) had been achieved. The duration of induction was significantly longer (P less than 0.001) with the slower infusion rates (104, 68 and 51 s), but the total dose used was significantly less (P less than 0.001) in these patients (1.2, 1.6 and 2.5 mg kg-1, respectively). The decrease in systolic and diastolic arterial pressure was significantly less in the 300-ml h-1 group at the end of induction and immediately after induction (P less than 0.01). The incidence of apnoea was also significantly less in the slower infusion group.

Aged↗

Pharmacokinetic interaction of propofol and fentanyl: single bolus injection study.

The effect of pretreatment with fentanyl on the pharmacokinetics of a single bolus of propofol was studied in 17 female patients (mean age 35 yr), ASA grade I. Eight patients received fentanyl 1.5 micrograms kg-1 5 min before induction of anaesthesia. In all patients anaesthesia was induced with propofol 2.5 mg kg-1 and maintained with halothane and nitrous oxide in oxygen. Pretreatment with fentanyl resulted in prolonged apnoea in all eight patients compared with three of nine patients in the control group. The pharmacokinetic values for propofol were described by a three-compartment mammillary model with rapid distribution phases (T1/2 alpha mean (SEM) 3.1 (2.0) min and T1/2 beta 44 (9.1) min) and a slower final phase of T1/2 gamma 520 (96) min. The clearance of propofol was rapid (mean 1.6 (0.24) litre min-1). Propofol was distributed initially into a relatively large central compartment (mean 23.7 (6.6) litre) and was extensively redistributed (mean Vss 593 (157) litre). There was no difference in the pharmacokinetic profile of propofol between the two groups.

Adolescent↗

Intra-operative pulmonary embolism. Detection by pulse oximetry.

A case is presented of a 49-year-old patient who had a pulmonary embolism during ovarian cystectomy. The only evidence of its occurrence was a sudden, marked reduction in arterial oxygen saturation as detected by a pulse oximeter. The diagnosis was confirmed 24 hours later by a chest radiograph and a ventilation perfusion scan. Anticoagulant treatment was instituted.

Female↗

Recovery of neuromuscular function after infusion or intermittent bolus doses of atracurium or vecuronium.

Neuromuscular block and postoperative recovery of grip strength and peak expiratory flow (PEF) were compared in patients receiving atracurium or vecuronium administered by continuous infusion or intermittent bolus doses. The same total dose of atracurium (0.92-0.98 mg kg-1) or vecuronium (0.16-0.18 mg kg-1) was given by both methods. A similar degree of neuromuscular block was attained in all groups. A control group receiving no neuromuscular blocking drugs was also studied. Grip strength and PEF were reduced significantly in all groups (less than 80% of preoperative value) 15 min after operation. This was most marked following infusion of vecuronium (less than 50%). Grip strength recovered in all groups in 30-60 min. PEF was still significantly less than control value at 90 min in all groups receiving neuromuscular blocking drugs.

Adult↗