Publications
42 results found
Watt SJ, Cook LB, Ohri S, et al., 1996, The relationship between anaesthetic uptake and cardiac output, ANAESTHESIA, Vol: 51, Pages: 24-28, ISSN: 0003-2409
- Author Web Link
- Cite
- Citations: 8
Walker TJ, Chakrabarti MK, Lockwood GG, 1996, Uptake of desflurane during anaesthesia., Anaesthesia, Vol: 51, Pages: 33-36, ISSN: 0003-2409
The amount of desflurane required to maintain an end-expired concentration of 8% was measured in 30 ASA 1 and 2 patients undergoing elective spinal surgery. The anaesthetic was administered using a computer-controlled closed circle system. After an initial period during which the expired concentration of desflurane was stabilised (4 min) the rate of uptake showed a bi-exponential decline. Mean cumulative usage of desflurane was 10.1 ml of liquid at 30 min, 14.8 ml at 60 min, 25.4 ml at 120 min, 35.8 at 180 min.
Cheam EW, Dob DP, Skelly AM, et al., 1995, The effect of nitrous oxide on the performance of psychomotor tests. A dose-response study., Anaesthesia, Vol: 50, Pages: 764-768, ISSN: 0003-2409
The effect of different nitrous oxide concentrations on the performance of psychomotor tests (inspection time, tapping frequency, critical flicker fusion, picture memory and time sense) was investigated in seven healthy volunteers. The results show a dose-related impairment of memory, a reduction in tapping frequency and an increase in inspection time. A paradoxical increase in critical flicker-fusion threshold was observed. There was no effect on critical fusion-flicker threshold or time sense. Recovery was incomplete for memory tests performed 20 min after withdrawal of nitrous oxide. Subjective effects persisted for several hours.
Gowrie-Mohan S, Chakrabarti MK, Lockwood GG, 1995, The estimation of inspired isoflurane concentration in a low-flow system., Anaesthesia, Vol: 50, Pages: 706-708, ISSN: 0003-2409
We have examined the predictability of inspired isoflurane concentration during low-flow anaesthesia using a to-and-fro breathing system. Twenty one adult patients requiring mechanical ventilation of the lungs during surgery took part in this study. Using a fresh gas flow of 2 l.min-1, the ratio of inspired isoflurane concentration to isoflurane vaporizer setting was found to be approximately 4/5th after 5 min of anaesthesia. The ratio was maintained throughout the procedure, except for a few minutes following each change in vaporizer setting.
Cheam EW, Lockwood GG, 1995, The use of a portable refractometer to measure desflurane., Anaesthesia, Vol: 50, Pages: 607-610, ISSN: 0003-2409
The measurement of volatile anaesthetic agents by infrared absorption is liable to interference by other gases which absorb infrared light. In particular, nitrous oxide may, in principle, interfere with the measurement of desflurane. On the other hand, the refractometer should be immune to such effects. We demonstrated that interactions may occur between desflurane and nitrous oxide with some gas analysers and that the refractometer remains a useful instrument.
Lockwood GG, 1994, Techniques of mechanical ventilation in closed and low flow systems., Anaesth Intensive Care, Vol: 22, Pages: 419-425, ISSN: 0310-057X
Lockwood GG, Landon MJ, Chakrabarti MK, et al., 1994, The Ohmeda Rascal II. A new gas analyser for anaesthetic use., Anaesthesia, Vol: 49, Pages: 44-53, ISSN: 0003-2409
The Ohmeda Rascal II is a multigas analyser and pulse oximeter for dedicated anaesthetic.use. It uses the Raman scattering of laser light to identify and quantify oxygen, nitrogen, carbon dioxide, nitrous oxide and three volatile anaesthetic agents. Its response times equal or better the published response times of infrared or photo-acoustic devices. It is linear within the clinical ranges of all gases and vapours, simple to use, requires no maintenance, holds its calibration well, and is a suitable monitor for clinical and research use.
COOK LB, LOCKWOOD GG, MOORE CM, et al., 1993, TRUE PATIENT-CONTROLLED SEDATION, ANAESTHESIA, Vol: 48, Pages: 1039-1044, ISSN: 0003-2409
- Author Web Link
- Cite
- Citations: 48
MENON DK, LOCKWOOD GG, PEDEN CJ, et al., 1993, IN-VIVO F-19 MAGNETIC-RESONANCE SPECTROSCOPY OF CEREBRAL HALOTHANE IN POSTOPERATIVE-PATIENTS - PRELIMINARY-RESULTS, MAGNETIC RESONANCE IN MEDICINE, Vol: 30, Pages: 680-684, ISSN: 0740-3194
- Author Web Link
- Cite
- Citations: 13
Lockwood GG, Chakrabarti MK, Whitwam JG, 1993, The uptake of isoflurane during anaesthesia., Anaesthesia, Vol: 48, Pages: 748-752, ISSN: 0003-2409
The uptake of isoflurane at a constant end-expired concentration of 1.5% in oxygen was studied in 15 women, ASA 1 or 2, undergoing elective total abdominal hysterectomy. The anaesthetic was administered by a simple computer-controlled to-and-fro closed system. After an initial period of wash-in to the system, the rate of uptake of isoflurane decreased bi-exponentially with a rapid reduction during the first 15 min. Perturbations from this bi-exponential decline reflect changes in cardiac output. The mean (SD) cumulative use of isoflurane was 4.5 (0.43) ml after 30 min and 7.3 (0.79) ml after 60 min.
Lockwood GG, Chakrabarti MK, Whitwam JG, 1993, A computer-controlled closed anaesthetic breathing system., Anaesthesia, Vol: 48, Pages: 690-693, ISSN: 0003-2409
We describe the design and working of a computer-controlled, closed anaesthetic breathing system which rapidly achieves and maintains a prescribed end-tidal concentration of isoflurane in oxygen. The system is simple to set up and not expensive; the only nonstandard component is a modified glass syringe. We have demonstrated that gas analysers may contribute as much as the patient to the accumulation of nitrogen within the breathing system. Details of our clinical experience with the system are presented in an accompanying article.
Lockwood GG, Chakrabarti MK, Whitwam JG, 1993, An evaluation of anaesthetic loss from a closed breathing system., Anaesthesia, Vol: 48, Pages: 564-567, ISSN: 0003-2409
We present the results of a laboratory study of the loss of isoflurane from a to-and-fro system, ventilated with oxygen, using a standard ventilator connected to the system via a long corrugated tube (the trunk) in place of the reservoir bag. No conventional fresh gas supply is used and isoflurane is injected as a liquid directly into the soda lime canister. The loss of isoflurane from the system due to mixing in the trunk was generally less than that lost by absorption into rubber and plastic system components. Glass syringes used for injection of liquid isoflurane were found to be a potential source of much greater leaks. The results showed that a to-and-fro system ventilated with oxygen via an open trunk functions as a virtually completely closed anaesthetic breathing system.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.