4. Kettering National Seminars Comprehensive Review: Pulmonary Diagnostic Testing D Questions With Complete Solutions

Blood Gas Sampling correct answer: - Puncture of a peripheral artery to obtain an ABG sample for direct measurement of pH, PaCo2, PaO2. a. Indications: 1. Evaluation of adequacy of pt's ventilation( PaCO2), Oxygenation ( PaO2), and acid base (pH). 2. Assess the need for therapeutic intervention ( oxygen therapy, mechanical ventilation, and/or diagnostic evaluation ( exercise desaturation) 3) Monitor the severity and progress of a documented disease process. b. There are three primary sites for obtaining an arterial blood gas: 1. Radial 2. Brachial 3. Femoral c. The radial artery is the first choice in most patients because of its accessibility and collateral blood flow. 1. The brachial artery is an appropriate alternative site. 2. The femoral artery is the last choice. d. The Modified Allen's Test is used to assess the collateral circulation in the hand prior to drawing a radial ABG. Modified Allen's Test correct answer: - It confirms that collateral blood flow is present. 1. The hand should pink up within 1-2 secs after releasing the ulnar artery. 2. If it does not- use another site. 3. Never attempt arterial punctures on patients with an indwelling dialysis shunt (Radial or Brachial), use another site.Samp Sampling hazards and problems correct answer: 1.* Disruption of blood flow- hematoma 2. Clotting 3.* Bleeding- hold pressure on site for a minimum of 5 mins. 4. Vessel spasm 5. Tissue trauma- muscle, bone, nerves 6. Anticoagulant therapy (heparin)- apply pressure to site longer. 7.* Air bubbles: -PaCo2- decrease toward 0 torr - PaO2- increases or decreases toward 150 torr - pH- increases 8.*Improper cooling: ( sample not iced) - PaCo2- increases - PaO2- decreases - pH- decreases 9.* Too much liquid Heparin: - PaCo2- decreases toward 0 - PaO2- increases or decreases toward room air ( 150) torr - pH-decreases toward 7.0 Capillary Sample correct answer: -* Capillary sample or heel sticks can also be used to obtain blood gas samples in infants. a) The site must be arterialized by wrapping it in a wet, warm cloth at 45C for 5-7 mins. b) The heel is cleansed with alcohol and a lancet is used for the puncture and is done deep enough to allow for free-flowing blood. c)* Results will show a consistent correlation with arterial pH and PcO2. d)* PO2 values do not correlate well with actual arterial blood. This is especially true when the arterial PO2 is above 60 torr. e) Capillary gases should be used to monitor oxygen therapy. Actual oxygen levels may be either higher or lower than what is measured in capillary sample. Arterial line correct answer: a.* Arterial catheters can be inserted into the radial, brachial, or femoral artery to provide continuous monitoring of systemic blood pressure and access for arterial blood sampling.