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Biomedical subjects

A C Norton

Publications and source records attributed to A C Norton.

15 recordsLinked to original sources
PubMed1997

A comparison of topical anaesthesia and retrobulbar block for cataract surgery.

It is possible to remove a cataract and insert an intraocular lens under topical anaesthesia (lignocaine 4% preservative-free eye drops) with a van Lint block. This study was performed to evaluate this anaesthetic technique. Nineteen patients having cataract surgery with topical anaesthesia and a van Lint block were compared with 21 patients who received a retrobulbar block and a van Lint block. There were no significant differences between the two groups in patient characteristics, mean cardiovascular stress of the procedure, experience of pain during the operation or willingness to have the same anaesthetic technique again. Topical anaesthesia with a van Lint block is feasible for cataract surgery and is potentially safer than other regional anaesthetic techniques.

Aged↗
PubMed1993

Antiemetic efficacy of prophylactic ondansetron in laparoscopic surgery: randomized, double-blind comparison with metoclopramide.

In a randomized, double-blind study, we have compared the prophylactic antiemetic efficacy of ondansetron with that of metoclopramide in 123 patients undergoing general anaesthesia for day-case gynaecological laparoscopic surgery. The patients received either i.v. ondansetron 4 mg or metoclopramide 10 mg immediately before a standard anaesthetic. The number of patients with no nausea or vomiting in the ondansteron group was 50 (82%) compared with 29 (47%) in the metoclopramide group (P < 0.001). In those patients with a previous history of postoperative nausea and vomiting, nausea was less severe in those receiving ondansetron compared with those receiving metoclopramide (P < 0.05). We conclude that preoperative prophylactic administration of i.v. ondansetron was superior to metoclopramide in preventing nausea and vomiting after general anaesthesia for day-case gynaecological laparoscopic surgery.

Adolescent↗
PubMed1990

The value of flumazenil in the reversal of midazolam-induced sedation for upper gastrointestinal endoscopy.

Fifty patients who underwent diagnostic upper gastrointestinal endoscopy after midazolam sedation were randomized to receive (after completion of the examination) either the benzodiazepine receptor antagonist flumazenil or an identical-looking placebo. The speed of recovery from sedation was assessed by reaction time testing, measurement of critical flicker fusion frequency, and the semi-quantitative SOCA scoring system. Measurements were made up to 6 h post examination in all subjects, and at 12 and 24 h in all in-patients (n = 20). Flumazenil-treated patients were significantly more alert than those who received placebo at 10 min, 30 min, 1 h and 2 h (P less than 0.001 in all instances). Thereafter the two groups were similar. There was no evidence of recurrence of sedation in flumazenil-treated patients, nor did this drug adversely affect the period of anterograde amnesia between the administration of midazolam and flumazenil.

Adolescent↗
PubMed1990

Induction agents for day-case anaesthesia. A double-blind comparison of propofol and midazolam antagonised by flumazenil.

Early postoperative recovery was studied using sedation scoring, measurement of flicker fusion frequency and completion of Trieger test figures in 60 male patients who presented for vasectomy under general anaesthesia as day patients. Anaesthesia was induced in groups 1 and 2 (20 patients each) with mean (SD) doses of 0.16 (0.04) mg/kg or 0.16 (0.03) mg/kg midazolam respectively; group 2 received flumazenil 0.55 (0.19) mg after completion of surgery. The remaining 20 patients (group 3) received propofol 1.50 (0.24) mg/kg. Anaesthesia was maintained with isoflurane vaporized in 33% oxygen and nitrous oxide in all patients. Flumazenil tended to improve tests of recovery after midazolam anaesthesia, but early recovery after propofol anaesthesia was associated with better psychomotor test results and less impairment of mental state as judged by sedation and amnesia scoring.

Adult↗
PubMed1989

Anaesthetic agents and their effect on tissue protein synthesis in the rat.

1. Rates of protein synthesis were measured, in vivo, in lung, liver, heart and skeletal muscle of young male rats. Groups of rats were exposed for 1 h duration to one of the following anaesthetic regimens: 1.4% halothane, 2.2% halothane, 1.4% halothane in 66% nitrous oxide, intravenous pentobarbitone (20 mg/kg) and intravenous midazolam (18 mg/kg) combined with fentanyl (2 micrograms/kg). Fractional rates of protein synthesis were determined by injecting [3H]phenylalanine (150 mumol/100 g body weight). 2. Liver protein synthesis was depressed significantly by all regimens, except midazolam/fentanyl, by up to 37.7% of control values. Lung protein synthesis was significantly reduced by all the anaesthetic agents by up to 30% of control rates. 3. The effects of the anaesthetic agents on skeletal muscle and heart were small and not statistically significant. 4. There was no evidence of ventilatory depression as manifested by changes in arterial blood gas partial pressures of CO2 and O2, except in the group treated with 2.2% halothane.

Anesthetics↗
PubMed1988

Lignocaine 2% with adrenaline for epidural caesarean section. A comparison with 0.5% bupivacaine.

A randomised double blind controlled trial of freshly prepared 2% lignocaine with 1/200,000 adrenaline and 0.5% plain bupivacaine was conducted on 60 women undergoing elective Caesarean section. The use of the former enabled epidural blockade to above the T6 dermatome to be established in a significantly shorter time than with bupivacaine (p less than 0.005). The quality of sensory blockade and incidence of complications was similar in the two groups. The solutions were of similar potency as measured by the volume required per segment blocked. Motor blockade was more intense with 2% lignocaine with adrenaline (p less than 0.03). More neonates had moderately depressed Apgar scores (5-7) at one minute in the lignocaine group but this difference was not statistically significant, and there was no difference in the distribution of Apgar scores at 3 minutes. Lignocaine with 1/200,000 adrenaline is a useful alternative to 0.5% plain bupivacaine when it is desired to establish rapidly epidural blockade for Caesarean section.

Adult↗
PubMed1984

A microprocessor-based system for measurement of gas exchange.

The basic physical measurements for determining gas exchange are difficult to make accurately even in a well-equipped, human-performance laboratory with experienced personnel. A fully automated system has been developed to achieve the accuracy of standard laboratory measurements. The application of this instrument extends from critical care to stress-testing. Real-time, multitasking software integrates the data collected from several transducers and analyzers and calculates up to several dozen physiological variables, which are range-checked for reasonableness. The operator is provided with user-friendly means to tailor the data-reporting and- collection functions of the system to his own needs and requirements. Because the instrument is controlled by software, the functions of calibration, measurement, timing, reporting, plotting, and data quality assurance are highly cost-effective. Extensive use of formal test procedures permits verifying all systems and data reliability; it also assures meeting the desired specifications. The ease of operation and high-quality results inherent in this system make it unsurpassed in gas-exchange measurements.

Computers↗
PubMed1982

An automated, indirect assessment of cardiac output during rest and exercise.

The present study describes a modification of the equilibration CO2-rebreathing technique for determining cardiac output (Q), utilizing the Beckman Metabolic Measurement Cart (MMC) to provide partial automation of the procedures described by Jones et al. (Clinical Exercise Testing. Philadelphia, PA: Saunders, 1975). Q was determined in six normal healthy males to establish the reliability of the technique at rest, and during exercise at power outputs of 49 and 98 W, or 300 and 600 kpm/min. An additional 11 patients, who were symptomatic for coronary artery disease and scheduled for right and left heart catheterization, were used in validating these procedures against Q determined by the thermodilution method. The automated CO2-rebreathing procedure was found to be reliable at rest and during exercise, and demonstrated a direct linear relationship with VO2 (r = 0.90). Also, this procedure correlated (r = 0.87) with the thermodilution method during supine rest, and both methods were quite consistent between trials within the same subject. It was concluded that the CO2-rebreathing procedure used in this study, as interfaced with the Beckman MMC, provides reasonable estimates of Q, both in patients during supine rest, and in normal healthy subjects at rest and during low to moderate levels of exercise.

Adult↗
PubMed1981

Oxygen monitors.

Explore the source record for details and available documents.

Anesthesia, Inhalation↗
PubMed1976

An automated system for assessing metabolic and respiratory function during exercise.

This paper provides a brief description of a new, totally automated system for assessing metabolic and respiratory function during exercise. This system was evaluated simultaneously against two established systems, one a computer-based system and the other a semiautomated system, to determine its validity over a wide range of metabolic levels, i.e., less than 2 to greater than 16 mets. A total of 112 males and females, 12-65 yr of age, performed either arm or leg exercises on a bicycle ergometer or treadmill, starting at approximately 2 mets and progressing by approximately 1 met/min to the point of volitional fatigue. Respiratory and metabolic assessments were made each minute during the entire exercise bout. Comparisons across the three systems demonstrated remarkable agreement, particularly when all potential sources of error for each system are considered. Although several statistically significant differences between two of the systems were noted at the lowest work levels, the difference in VO2 between any two systems never exceeded 1.1 ml/kg-min.

Adolescent↗