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KNOWLEDGE COMPETENCIES
Interpret normal and abnormal arterial blood gas (ABG) results and determine common management strategies for treatment.
Identify indications, complications, and management strategies for artificial airways, oxygen delivery, and monitoring devices.
Identify indications, principles of operation, complications, and management strategies for mechanical ventilation.
Explain the concepts of respiratory muscle fatigue, rest, and conditioning as they relate to the mechanically ventilated weaning patient.
Discuss essential components for successful weaning from short- and long-term ventilation, and multidisciplinary institutional approaches to the care of prolonged mechanically ventilated patients.
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DIAGNOSTIC TESTS, MONITORING SYSTEMS, AND RESPIRATORY ASSESSMENT TECHNIQUES
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Arterial Blood Gas Monitoring
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Arterial blood gas (ABG) monitoring is frequently performed in critically ill patients to assess acid-base balance, ventilation, and oxygenation. An arterial blood sample is analyzed for oxygen tension (PaO2), carbon dioxide tension (PaCO2), and pH using a blood gas analyzer. From these measurements, several other parameters are calculated by the blood gas analyzer, including base excess (BE), bicarbonate (HCO–3), and oxygen saturation (SaO2). Fractional arterial SaO2 can be directly measured, if a co-oximeter is available. Normal ABG values are listed in Table 5-1.
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ABG samples are obtained by direct puncture of an artery, usually the radial artery, or by withdrawing blood through an indwelling arterial catheter system. A heparinized syringe is used to collect the sample to prevent clotting of the blood prior to analysis. Blood gas samples are kept on ice unless there is the ability to immediately analyze to prevent the continued transfer of CO2 and O2 in and out of the red blood cells. ABG analysis equipment is often kept in or near the critical care unit to maximize accuracy and decrease the time for reporting of results. Additionally, portable point-of-care devices are available at many hospitals, which ...