Anesthesia Machines
Purpose
• Anesthesia units dispense a mixture of gases and vapors and vary the proportions to control a patient’s level of consciousness and/or analgesia during surgical procedures.Functions
• Provide oxygen (O2) to the patient.• Blend gas mixtures that can include (besides O2) an anesthetic vapor, nitrous oxide (N2O), other medical gases, and air.
• Facilitate spontaneous, controlled, or assisted ventilation with these gas mixtures.
• Reduce, if not eliminate, anesthesia-related risks to the patient and clinical staff.
Anesthesia delivery
• The patient is anesthetized by inspiring a mixture of O2, the vapor of a volatile liquid halogenated hydrocarbon anesthetic, and, if necessary, N2O and other gases.• Because normal breathing is routinely depressed by anesthetic agents and by muscle relaxants administered in conjunction with them, respiratory assistance — either with an automatic ventilator or by manual compression of the reservoir bag — is usually necessary to deliver the breathing gas to the patient.
Principles of operation
• An anesthesia system comprises four basic subsystems:– a gas supply and control circuit;
– a breathing and ventilation circuit;
– a scavenging system;
– a set of system function and breathing circuit monitors (e.g., inspired O2 concentration, breathing circuit integrity).
Safe practice of anesthesia
• Anesthesia machines incorporate a number of alarms that indicate:
– levels and variations of several physiologic variables and parameters associated with cardiopulmonary function; and/or– gas and agent concentrations in breathed-gas mixtures.
Safe practice of anesthesia
• Anesthesia machines must monitor:
– O2 concentration;
– airway pressure; and either
– the volume of expired gas (Vexp); or
– the concentration of expired CO2 (capnography).
• Stand-alone monitors may be used to track other essential variables:
– electrocardiogram;
– SpO2;
– blood pressure (invasive / non-invasive);
– temperature.
MAJOR COMPONENTS
• Gas Supply• Pressure Regulators
• Flowmeters
• Vaporizers
• Safety Devices
• Breathing System
Breathing circuits used in continuous-flow systems
Preventive Maintenance
• Test apparatus and supplies:
– Lung simulator with adjustable compliance or ventilator tester
– Pressure gauge or meter with 2cm H2O resolution, from -20 to +120 cm H2O
– Various breathing circuit adapters
– Leakage current meter or electrical safety analyzer
– Ground resistance ohmmeter
– Additional items as required for specific manufacturers’ procedures
Preventive Maintenance
• Qualitative tests:
– Chassis/Housing
– Mount/Fasteners
– Casters/Brakes
– AC Plug
– Line Cord
– Strain Reliefs
– Circuit Breaker/
– Tubes/Hoses
– Cables
– Fittings/Connectors
– Filters
– Controls/Switches
– Fan
– Battery/Charger
– Indicators/Displays
– Alarms/Interlocks
– Labeling
– Accessories
– Bellows
• Quantitative tests:
– Grounding resistance [≤0.5 Ω]
– Leakage current [≤300μA chassis]
– Modes and settings [±10% accuracy]
– Monitors and Alarms [±10% accuracy]
– Alarms tested:
• Airway pressure
• Tidal volume
• FIO2
تعليقات
إرسال تعليق