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The Anesthesia Gas MachineLast updated Feb 2006. Comments or
criticism to the author at: |
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The Anesthesia Gas MachineLast updated Feb 2006. Comments or
criticism to the author at: |
DRE is a professional supplier of new, preowned, and refurbished anesthesia machines, surgical tables, patient monitors, surgery lights, and a wide variety of used medical equipment.
Click on the headings in the table of contents for this page and you will be taken directly to each section.
The Anesthesia Gas Machine is a large, current, full-text, illustrated, comprehensive treatment of all aspects, from the University of Detroit Mercy. Last revised Jun 2004. It covers gas supply, the internal pneumatics and other processing, delivery to the patient (circuits, ventilators), disposal (scavenging systems), an extensive section on the gas machine checklist, vaporization, compressed gases, and a variety of smaller topics (malignant hyperthermia, medical legal, etc.). The last portion is a "Test Yourself", which covers selected clinical implications in a question and answer format. By the author of the chapter on equipment in Nagelhout and Zaglaniczny (Eds.) Nurse Anesthesia 3rd ed. 2005.
World Anaesthesia Online has several articles posted which relate to practice and conditions overseas.
From Walter Reed, the USUHS/US Army 885A Field Anesthesia Machine Tutor is an interesting document even for those who may never use equipment under wartime or mobile army surgical hospital conditions. It contains the 885A description and safety review, Vernitrol vaporizer theory & use, and references.
The Washington State University Anesthesia Equipment Outline is comprehensive. It covers circuits, vaporizers, gas cylinders, pressure regulators, flowmeters, scavenging, ventilators, endotracheal tubes, and is referenced. Much of the content applies to any anesthetizing equipment.
A recently redesigned site from Drager Medical showcases new products such as Fabius GS, and Narkomed 6400 gas machines. The Datex-Ohmeda site has an overview of Datex-Ohmeda gas machines, including Aestiva and S/5 ADU, which gives some details of their features. Vital Signs and King Systems make pictures and descriptions of their circuits and airways available online.
Checklists and Pre-Use checkout of the anesthesia gas machine are covered in several places. The checklist given at Anesthesia Apparatus Checkout Procedure, does not correspond to the current FDA checklist. However, it has a unique and useful feature: giving potential faults the user might discover while checking each component. The University of Michigan checkout has color photos of the Narkomed 2B, and is well-presented. It dates from 1994. Putting it all together- Checklist, Medicolegal, Cleaning and Sterilization (a subset of the overview mentioned earlier on this page) has a section which presents a minimum checklist (when time to check the machine is not available), and a modified checklist designed to eliminate common faults (and add a few reminders not written by the FDA). Finally, Dr J. Andrews (author of equipment chapters in texts edited by Miller et al. and Barash et al.) writes on Troubleshooting the anesthesia gas machine, which in part addresses checkout.
The last few years have seen a revolutionary change in a component of gas machines whose formulation dates to the First Word War- soda lime carbon dioxide absorption. Because the methyl ethyl ethers (desflurane, enflurane, isoflurane) break down to carbon monoxide, and sevoflurane produces a toxic breakdown product (Compound A) in dry soda lime or barium hydroxide lime, research has focused on the clinical significance of the problem, and potential solutions. Since 2000, a potential solution has been found in the form of a change in carbon dioxide absorption granule formulation- elimination of the "activators" (strong bases sodium and potassium hydroxide).
Baralyme has been withdrawn in Aug 2004: "Allied Healthcare Products, Inc. (NASDAQ NM : AHPI) filed an 8-K on 8/30, in which the Company reported that on 8/27, it entered into an agreement with Abbott Laboratories pursuant to which Allied will cease production of its product Baralyme(R), will, within sixty days, effect the withdrawal of Baralyme(R) product held by distributors and will pursue the development of a new carbon dioxide absorbent product." more...
Read more by searching for "soda lime" in Anesthesiology or Anesthesia and Analgesia.
The Association for Low Flow Anaesthesia (ALFA) is a comprehensive site for closed circuit and low flow techniques and information. Datex-Ohmeda has a clinical bulletin section on low flow (search in the archive on the category "low flow" gives several articles).
Michael Olympio offers a fascinating analysis of the effect of new gas machine designs on patient safety at Modern Anesthesia Machines Offer New Safety Features. He has also made a powerpoint available for download on Comparison of Breathing Circuits of Modern Anesthesia Machines. Both are well-worth your study.
The Low-Pressure Alarm Condition: Safety Considerations and the Anesthesiologist's Response gives an algorithm and detailed analysis for troubleshooting these alarms.
The Oklahoma State University Safety Library: Compressed gases links to many government, university, and manufacturer's documents. One of them, the Compressed Gas Association, contains safety bulletins and technical publications. One section is devoted to nitrous oxide safety and security.
Medical gas contamination, especially as supplied by pipelines, is a continuing source of mortality and morbidity. See JCAHO Sentinel Alert: Medical gas mix-ups which reports on two deaths and five injuries occurring in 2000.
A Bibliography on equipment and liability is published at the ASA Closed Claims Project. Also at that site is an ASA Newsletter article by Kaplan, which contains data on equipment problems, and how they impact patient safety.
The Malignant Hyperthermia Association of the US (MHAUS) contains several worthwhile items. Click Online Brochures at the left, and select "Managing MH: Drugs, Equipment, and Dantrolene Sodium", or "Preventing Malignant Hyperthermia: An Anesthesia Protocol". Or click Professional's Info Center on the left, and select either "MH Online Brochure", or "Medical FAQ". Using breathing circuits and ventilators has a section discussing the equipment implications of malignant hyperthermia.
ASTM lists the scope and subcommittees of Committee F-29 on Anesthetic and Respiratory Equipment, also refers to the standards writing process and gives contact information. ASA standards relating to Pre and Post Anesthesia care, and Intraoperative Monitoring standards have equipment implications.
GasMan is a commercial product which allows one to simulate and experiment with anesthesia delivery systems. One can vary fresh gas flow, minute ventilation, circuit type, patient body habitus, cardiac output, vaporizer settings, and other parameters, while observing the effects on volatile agent uptake and distribution (in several body compartments), excretion, and cost. Fascinating and worthwhile (but not free).
A "virtual anesthesia machine" is an animated gas machine illustration on computer screen, which is modifiable when the user selects different gas flows, vapor concentrations, etc. It requires Shockwave, or there is a downloadable version.
The Review of Currently Used Inhalation Anesthetics Part I has some implications for equipment and how it is used. Part II has good pictures and descriptions of several topics including how to fill vaporizers.
Two very worthwhile sites are OSHA Fact Sheet (1991) on WAGs, and the Update on WAGs (July 1999), which is from the ASA Newsletter. Finally, there is a very comprehensive and current document at the ASA on Waste anesthesia gases.
This page is one chapter of many in the Virtual Anaesthesia Textbook. Please direct all comments about the organisation of this chapter, corrections to links, and suggestions for additions to: Michael Dosch CRNA MS, Department of Anesthesia. St Joseph Mercy Oakland, Pontiac Michigan USA; Director and Co-Chair of Nurse Anesthesia, University of Detroit Mercy
Questions about the Virtual Anaesthesia Textbook project itself should be e-mailed to Chris Thompson.
