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Biomedical subjects

J A Langton

Publications and source records attributed to J A Langton.

14 recordsLinked to original sources
PubMed1992

Movements of the vocal cords on induction of anaesthesia with thiopentone or propofol.

Using a fibreoptic laryngoscope, we have recorded on video tape the movements of the vocal cords after induction of anaesthesia with either propofol or thiopentone. The angle formed by the vocal cords decreased after induction of anaesthesia in both groups. This reduction in angle was significantly greater in the thiopentone group. The vocal cords closed completely in four patients in the thiopentone group and one patient in the propofol group. This difference may be explained by greater depression of laryngeal reflexes by propofol and this may account for the lower incidence of laryngospasm after induction of anaesthesia with propofol in comparison with thiopentone.

Adult↗
PubMed1992

Regurgitation of gastric contents during general anaesthesia using the laryngeal mask airway.

We have investigated the incidence of regurgitation of gastric contents during general anaesthesia administered via a laryngeal mask airway (LMA) or face mask and Guedel airway in 56 patients with no risk factors for regurgitation. Patients swallowed a gelatin capsule containing methylene blue 10 min before induction of anaesthesia. Fibreoptic laryngoscopy in the LMA group or conventional laryngoscopy in the face mask group was performed at the end of surgery. Dye was observed within the laryngeal mask in seven of 28 patients (25%). No patients in the face mask-Guedel airway group regurgitated dye (P = 0.005). There was no evidence of aspiration of dye.

Adult↗
PubMed1992

Effect of the laryngeal mask airway on lower oesophageal sphincter pressure in patients during general anaesthesia.

We have studied the tone of the lower oesophageal sphincter (LOS) in 40 adults undergoing routine body surface surgery and allocated randomly to receive anaesthesia either by face mask and Guedel airway or by laryngeal mask airway. In the laryngeal mask group there was a mean (SEM) decrease in barrier pressure (LOS minus gastric pressure) of 3.6 (1.4) cm H2O, compared with a mean increase of 2.2 (1.2) cm H2O in the face mask group (P < 0.005).

Adult↗
PubMed1991

Effect of prior administration of cold saline on pain during propofol injection. A comparison with cold propofol and propofol with lignocaine.

A single-blind, randomised, controlled study was undertaken to compare the efficacy of three methods of preventing pain during injection of propofol on induction of anaesthesia. Patients were allocated randomly to receive unmodified propofol, propofol with 0.05% lignocaine, propofol at 4 degrees C and unmodified propofol preceded by 10 ml of 0.9% saline at 4 degrees C. Prior injection of cold saline reduced the incidence of pain and discomfort significantly (22%) compared with unmodified propofol (75%; p less than 0.005) and was similar to that after cold propofol (33%) and propofol with lignocaine (44%). There was no significant difference between the treatment groups.

Adult↗
PubMed1990

Comparison of four pulse oximeters: effects of venous occlusion and cold-induced peripheral vasoconstriction.

The ability of four pulse oximeters (the Ohmeda 3700, Nellcor N100 and N200 and the Datex Oscar) to detect hypoxaemia was determined in the presence of venous obstruction and cold-induced peripheral vasoconstriction. Significant increases in detection time for hypoxaemia were found in both cases. There were no significant differences in detection time between the instruments, although the Ohmeda 3700 displayed smaller values of SaO2 under certain conditions. Peripheral vasoconstriction was induced using three differing methods which gave differing results, thus emphasizing the importance of methodology in assessments of pulse oximetry.

Body Temperature↗
PubMed1990

Effect of motion artefact on pulse oximeters: evaluation of four instruments and finger probes.

The ability of the Ohmeda 3700, Nellcor N200, Datex Satlite Plus and Simed S100 pulse oximeters to detect induced hypoxaemia in the presence of motion artefact was assessed, under conditions of controlled vibration using an industrial vibration facility. Vibration at 4 Hz and 8 Hz induced increases in detection time for hypoxaemia and spurious decreases in the displayed SaO2 in some of the oximeters tested. Finger-dependent differences in oximeter performance and pulse rate registration were noted especially in those oximeters without ECG linkage (Ohmeda 3700 and Simed S100). Subsequently, eight different pulse oximeter finger probes were assessed for those characteristics that may predispose to motion artefact. There were marked differences in the mass of the probes, the forces exerted on the test finger and in the force required to displace the probes from the subject's finger. Differences in both the microprocessor programmes and the physical characteristics of the finger probes may explain the observed differences in function. Similar studies should form part of the standard evaluation of new pulse oximeters.

Adult↗
PubMed1990

Pressure generated during insertion of lumbar epidurals. A comparison with the Portex epidural injection simulator.

The aim of this study was to measure pressures exerted during insertion of lumbar epidurals in obstetric patients. The pressures were compared with those obtained when the Portex epidural injection simulator was used, and were significantly greater when a saline technique was used compared to those when air was used (p less than 0.05). There were no differences between the pressures obtained with the simulator and those measured in vivo.

Air↗
PubMed1988

Anaphylaxis following "Hexabrix" during routine coronary angiography.

A case is described of an anaphylactic reaction to "Hexabrix 320" radiographic contrast medium in a patient undergoing routine coronary angiography. The case is reported because such reactions to "Hexabrix" are considered rare, because the patient was pretreated with hydrocortisone and chlorpheniramine, and because of the continuous monitoring that occurred during the procedure.

Aged↗