Biomedical subjects

M L Tatnall

Publications and source records attributed to M L Tatnall.

4 recordsLinked to original sources

PubMed1983

Controlled anaesthesia: a clinical evaluation of an approach using patient characteristics identified during uptake.

The performance of a system to control the alveolar concentration of halothane in patients undergoing halothane and nitrous oxide or halothane anaesthesia with controlled ventilation has been evaluated. The method involved the identification and quantification of the uptake characteristics of patients from their early response to the anaesthetic and implements the vaporizer control necessary to achieve and maintain a desired alveolar halothane concentration. Initial targets are based on the concept of MAC, but modifications to the desired alveolar concentration may be effected readily by the anaesthetist at any time during the procedure if evaluation of the normal clinical signs indicates inappropriate depth of anaesthesia. The results obtained during anaesthesia for routine surgery in 80 patients demonstrated that the system was accurate, stable, robust and able to adapt for variability between patients in the uptake of halothane.

Anesthesia, Inhalation↗

PubMed1981

Controller anaesthesia: an approach using patient characteristics identified during uptake.

A system to control the alveolar anaesthetic concentration of patients undergoing halothane anaesthesia with controlled ventilation is described. Parameters characterizing the alveolar concentration response are determined on-line from breath-by-breath measurement of the inspired and end-tidal concentrations and the mixed venous anaesthetic partial pressure is estimated throughout the procedure. The method does not depend on the use of reference models or pre-programming and the inspired concentration required to control the alveolar concentration is determined as induction proceeds. Results using both computer simulations and data from patients undergoing routine clinical anaesthesia are analysed. Off-line verification results illustrate the operation of the technique and in 20 cases the inspired concentration, as controlled by the anaesthetist, was compared with that predicted by the automated system. These results indicate the feasibility of the system as a method for the control of anaesthesia.

Anesthesia, Inhalation↗

PubMed1979

Breath-by-breath halothane monitoring during anaesthesia. A study in children.

The use of a halothane meter in routine paediatric anaesthesia with controlled ventilation is described. The results demonstrate the accuracy achieved in the control of the alveolar halothane concentration. Measurement of the alveolar halothane concentration revealed responses to surgical stimulation otherwise obscured by neuromuscular blockade, and this may indicate insufficient depth of anaesthesia.

Adolescent↗

PubMed1978

A rapid-response u.v. halothane meter.

The design and performance characteristics of an instrument for monitoring halothane concentrations which operates on the principle of the absorption of u.v. light are described. The innovation is that the entire exhaled breath passes through the sample cell, enabling the breath-by-breath halothane concentration to be measured accurately and instantaneously. Stablized power supplies, solid-state circuitry and filtering make the instrument stable and selective. A valve prevents rebreathing of gas exposed previously to u.v. light in the sample cell. Inspired and end-tidal concentrations are displayed digitally and an analog output is available also. Zero and gain drift were negligible after an initial settling period, and interference from other respiratory gases was not detectable. The monitor is suitable for use during anaesthesia for adults and children.

Adult↗