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KEY POINTS

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KEY POINTS

  1. A basic understanding of the anesthesia delivery system and its components is essential for the provision of safe patient care.

  2. Use error is the most common cause of adverse outcomes in relation to anesthesia gas delivery equipment. User education must be emphasized, and there must be a thorough in-service whenever there is a new user or new equipment is introduced.

  3. The anesthesia workstation must be checked each day before anesthetizing the first patient and again whenever any change is made to the system. A shortened checkout should precede each administration of anesthesia.

  4. Because of the diversity of the newer workstations, in 2008 the ASA published guidelines to act as a template for developing preanesthesia checkout procedures. Presently, a positive pressure check for leaks in the low-pressure system is recommended for traditional Dräger Narkomed machines and a negative pressure check for GE-Datex machines.

  5. An O2 analyzer in the patient circuit is essential to detect a hypoxic mixture. It should be automatically enabled and the low O2 concentration alarm set whenever the machine is capable of delivering an anesthetic gas mixture.

  6. In the event of a severe machine or gas delivery system malfunction, an alternative means for ventilating the patient’s lungs with O2 (or room air) must be immediately available. Thus, a self-inflating manual ventilation device (eg, “Ambu bag”), whose function has been checked and verified before use, must be available and functioning in each anesthetizing location.

  7. Vaporizers are agent-specific. Erroneous filling must be avoided; agent-specific filling devices should be used.

  8. Use of freestanding vaporizers downstream from the common gas outlet can be hazardous and must be avoided.

  9. Anesthesia circuits are classified as rebreathing (ie, no CO2 absorption) or nonrebreathing (including a CO2 absorber; eg, circle system). In all circuits, the greater the fresh gas flow, the closer inspired gas composition approaches that of fresh gas.

  10. A standing bellows design is preferred for traditional ventilators as it makes a leak in the breathing system more obvious (ie, partial filling or collapse of the bellows implies a leak in the breathing circuit). This design requires that the ventilator relief valve incorporate a positive end-expiratory pressure (PEEP) mechanism.

  11. Waste anesthesia gases should be scavenged to minimize occupational exposure to halogenated agents. The National Institute for Occupational Safety and Health (NIOSH) recommends that exposure of operating room workers to halogenated agents should be kept below 2 ppm. N2O levels should be controlled so that no worker is exposed at time-weighted average concentrations greater than 25 ppm. This last guide should result in levels of approximately 0.5 ppm of the halogenated agents.

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INTRODUCTION

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The anesthesia delivery system comprises the anesthesia machine, anesthesia vaporizer(s), ventilator, breathing circuit, and waste gas scavenging system. It is the anesthesia caregiver’s constant companion in the operating room or procedure room. Whether a patient is to receive general anesthesia, regional anesthesia, or monitored anesthesia care, the anesthesia ...

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