Oxygen Analyzer Clinical Application & Evaluation of Oxygenation PDF

Chapter 18 Analysis and Monitoring of Gas Exchange Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.  Analysis vs. Monitoring  Laboratory analysis: discrete measurements of fluids or tissue that m...

Chapter 18 Analysis and Monitoring of Gas Exchange Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.  Analysis vs. Monitoring  Laboratory analysis: discrete measurements of fluids or tissue that must be removed from body  Such measurements are made with an analyzer  Monitoring is an ongoing process by which clinicians obtain & evaluate dynamic physiological processes in a timely manner, usually at bedside  This is done with monitor Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 2 Invasive vs. Noninvasive Procedures  Invasive procedures require insertion of sensor or collection device into body  Noninvasive monitoring is means of gathering data externally  Generally, invasive procedures provide more accurate data but carry greater risk  After gradient between invasive & noninvasive method is established, trends in change of noninvasive method can be useful in making clinical decisions Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 3  Measuring FIO2  Most bedside systems to measure FIO2 use electrochemical principles  2 most common: 1. Polargraphic (Clark) electrode- needs battery 2. Galvanic fuel cell- no battery needed  Response times for Clark electrodes = about 10 to 30 seconds  Response times for galvanic fuel cells = 60 seconds Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 4  Troubleshooting O2 Analyzers  Calibration according to manufacturer’s recommendation must be done before using device  Failure to calibrate or inconsistent readings are signs of malfunctioning  Best way to avoid problems is through preventative maintenance  If analyzer fails to calibrate, problem could be related to:  Low batteries, sensor depletion, electronic failure Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 5  Sampling & Analyzing Blood Gases  Analyzing arterial blood samples is important part of diagnosing & treating patients with respiratory failure  Radial artery is most often used because:  Near surface & easy to stabilize  Collateral circulation usually exists (confirmed with the Allen test)  No large veins are near  Radial puncture is relatively pain free  Arterial cannulation can be done if frequent sampling is needed Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 6  Arterial Sampling Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 7  Arterial Sampling (cont.)  Modified Allen’s test:  Done prior to radial artery puncture ONLY  Normal test indicating collateral circulation - hand flush pink within 5-10 seconds  Cannot be performed on critically ill patients who are uncooperative or unconscious Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 8  Modified Allen Test Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 9  Arterial Sampling (cont.)  Sample volume of 0.5 to 1 mL of blood is adequate  Actual volume depends on:  Anticoagulant used  Requirements of specific analyzer used  Whether or not other tests will be performed on obtained sample Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 10  Arterial Sampling (cont.)  Important transmission-based and safety precautions:  Never recap used needle without safety device; never handle using both hands, & never point it toward any part of body  Never bend, break, or remove used needles from syringes by hand  Always dispose of used syringes, needles, & other sharp items in appropriate puncture-resistant sharps containers Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 11  Indications for Arterial Sampling  Sudden, unexplained dyspnea  Acute shortness of breath/tachypnea  Abnormal breath sounds  Cyanosis  Heavy use of accessory muscles  Changes in ventilator settings  CPR  Diffuse infiltrates in chest radiograph  New infiltrates in CXR  Sudden cardiac arrhythmias  Acute hypotenesion Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 12  Blood Sample Analysis  Clinicians can avoid most pre-analytical errors by ensuring that sample is:  Obtained anaerobically  Properly anticoagulated  Analyzed within 10 to 30 minutes Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 13  Interpretation of ABGs  Interpret oxygenation status  PaO2 (see below)  SaO2 (normal = 95100%)  CaO2 (normal = 1820 vol%) PaO2 6079 mm Hg = mild hypoxemia PaO2 4059 mm Hg = moderate hypoxemia PaO2