Kettering - Pulmonary Diagnostic Testing Questions With Complete Solutions

arterial puncture correct answer: puncture of a peripheral artery to obtain an arterial blood sample for direct measurement of pH, PaCO2, PaO2 indications for arterial puncture correct answer: evaluation of the adequacy of a patients ventilation (PaCO2), oxygenation (PaO2) and/or acid base status (pH) assess the need for therapeutic intervention (i.e., oxygen therapy, mechanical ventilation, etc) and/or diagnostic evaluation (i.e., exercise desaturation) monitor the severity and progression of a documented disease process there are three primary sites for obtaining an ABG correct answer: radial brachial femoral - if BP is low (60/40) the radial artery is the first choice in most patients because of its accessibility and collateral blood flow correct answer: the brachial artery is an appropriate alternative site the femoral artery is the last choice the modified allens test correct answer: used to assess the collateral circulation in the hand prior to drawing a radial ABG a positive modified allen's test confirms that collateral blood flow is present correct answer: the hand should pink up within 1-2 seconds after releasing the ulnar artery if it does not - use another site never attempt arterial punctures on patients with an indwelling dialysis shunt (radial or brachial), use another site only performed for radial ABGs, performed every single time ABG sampling hazards and problems correct answer: disruption of blood flow - hematoma clotting bleeding - hold pressure on site for a minimum of 5 mins or until bleeding stops vessel spasm tissue trauma - muscles, bone, nerves anticoagulant therapy (heparin) - apply pressure to site longer air bubbles in ABG sample correct answer: PaCO2 decreases toward 0 torr PaO2 increases or decreases toward 150 torr pH increases improper cooling of ABG sample (sample not iced) correct answer: PaCO2 increases PaO2 decreases pH decreases too much liquid heparin in ABG sample correct answer: PaCO2 decreases toward 0 PaO2 increases or decreases towards room air (150 torr) pH decreases toward 7 capillary samples or heel sticks can also be used to obtain blood gas samples in infants correct answer: the site must be arterialized by wrapping it in a wet, warm cloth at 45C for 5-7 minutes 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 results will show a consistent correlation with arterial pH and PCO2 PO2 values do not correlate well with actual arterial blood, this is especially true when the arterial PO2 is above 60 torr capillary gases should not be used to monitor oxygen therapy, actual oxygen levels may be either higher or lower than what is measured in capillary sample umbilical arterial lines are used for newborn babies correct answer: a catheter is inserted into the umbilical artery at the ut end of the umbilical cord, the safest place for the tip of the umbilical arterial catheter is at L-3, which is above the bifurcation of the aorta but below the renal arteries umbilical artery PO2 may be used to regulate FiO2 - true arterial sample catheter is in a post-ductal location and may be used to identify right-to-left shunting across the ductus arteriosus there are 2 umbilical arteries advantages of umbilical artery catheter (UAC) correct answer: allows continuous monitoring of blood pressure arterial samples for ABG and other lab analysis blood replacement (transfusions) arterial line correct answer: 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 a transducer is used to convert pressure (analog signal) to an electrical signal (digital signal) which is measured, displayed and recorded by a monitor transducer of arterial line should be level with the catheter for accurate measurement of pressure correct answer: if transducer is above catheter, displayed pressure is lower than actual if transducer is below catheter, displayed pressure is higher than actual sampling technique from A line correct answer: withdraw approximately 3-5 mL of fluid from catheter (waste solution) attach blood gas syringe to sampling port and collect blood sample return waste solution to patient cause stopcock and flush catheter and tubing failure of arterial waveform to return indicates the stopcock was not turned to the correct position complications of A line correct answer: thrombosis/embolism bleeding infection hematoma arterial spasm blood gas analyzers directly measure correct answer: PCO2 -