Biomaterial Database

Preparing a new generation anaesthetic machine for patients susceptible to malignant hyperthermia. 2003

L H B Schönell, and C Sims, and M Bulsara

Department of Anaesthesia, Princess Margaret Hospital for Children and Department of Public Health, The University of Western Australia, GPO Box D184, Perth, W.A. 6840.

Anaesthetic machines are prepared for use with patients who are susceptible to malignant hyperpyrexia (MH) by flushing with oxygen at 10 l/min for ten minutes to reduce the anaesthetic concentration to 1 part per million (ppm) or less. Anaesthetic workstations are now often used in place of traditional machines. Workstations have greater internal complexity, and it is not known if they can be made safe for susceptible patients by flushing with oxygen. We used a high sensitivity infrared gas analyser to measure the washout of isoflurane from five Datex-Ohmeda workstations. Measurements were then repeated with a patient breathing circuit. Isoflurane washout occurred in an exponential manner. The time to reach a concentration of 1 ppm at the fresh gas outlet was 17 +/- 7 minutes, and all machines had reached less than 2 ppm by ten minutes. The washout of isoflurane from the machine and patient breathing circuit was much slower than from the machine alone, with a concentration less than 2 ppm reached only after 30 minutes. We conclude that the Datex-Ohmeda workstation can be prepared for use in MH susceptible patients by flushing with oxygen at 10 l/min for ten minutes. Flushing of the patient breathing system is not straightforward, and we recommend using a clean T-piece circuit. If the circle system and ventilator are required for anaesthesia, we suggest using new breathing hoses, rebreathing bag and soda lime cartridge, and ventilating an artificial lung for 30 minutes with a fresh gas flow rate of 10 l/min and tidal volume of 1 litre.

UI	MeSH Term	Description	Entries
D007530	Isoflurane	A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
D008305	Malignant Hyperthermia	Rapid and excessive rise of temperature accompanied by muscular rigidity following general anesthesia.	Hyperpyrexia, Malignant,Hyperthermia, Malignant,Malignant Hyperpyrexia,Anesthesia Related Hyperthermia,Hyperthermia of Anesthesia,Anesthesia Hyperthermia,Hyperthermia, Anesthesia Related,Malignant Hyperpyrexias
D004198	Disease Susceptibility	A constitution or condition of the body which makes the tissues react in special ways to certain extrinsic stimuli and thus tends to make the individual more than usually susceptible to certain diseases.	Diathesis,Susceptibility, Disease,Diatheses,Disease Susceptibilities,Susceptibilities, Disease
D004867	Equipment Design	Methods and patterns of fabricating machines and related hardware.	Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000776	Anesthesiology	A specialty concerned with the study of anesthetics and anesthesia.
D018685	Anesthetics, Inhalation	Gases or volatile liquids that vary in the rate at which they induce anesthesia; potency; the degree of circulation, respiratory, or neuromuscular depression they produce; and analgesic effects. Inhalation anesthetics have advantages over intravenous agents in that the depth of anesthesia can be changed rapidly by altering the inhaled concentration. Because of their rapid elimination, any postoperative respiratory depression is of relatively short duration. (From AMA Drug Evaluations Annual, 1994, p173)	Inhalation Anesthetic,Inhalation Anesthetics,Anesthetic Gases,Anesthetic, Inhalation,Gases, Anesthetic