In order to get accurate readings, it is important to level and zero the lines prior to waveform analysis. SvO2 65-70% (typical oxygen extraction is 25-30%).So, what are the normal values for these measurements? Using this measurement has many caveats and will require an entire post in itself! This is a continuous waveform measurement and can also be assessed with a CVC sans PAC. Do not wedge a PAC unless there is an order to do so from the clinician.įinally, CVP is a representation of RV preload and pressure. Not all PACs will wedge, often due to positioning.
Allow the balloon to deflate passively and ensure a PAP waveform is present following wedging. Only insert air until the waveform is “wedged”, freeze the screen, and deflate the balloon. Since you do not want to be wedged for longer than 15 seconds, preparing to get a still of the wedged waveform, or “freezing” the screen, will allow you time to assess the waveform once the air is removed from the balloon. Due to the occlusion created by wedging, it is important to have your monitor set up to “freeze” the screen when a wedge waveform is achieved.
Between 0.5-1.5mL (a specific syringe exists that only allows 1.5mL, try not to lose it!) is injected into the red lumen, this causes the balloon to occlude antegrade flow from the distal PA to the pulmonary capillaries. PAWP is obtained by utilizing the balloon port of the PAC. Basically, this is a measurement of preload, or filling volume, to the left ventricle (LV). PAWP is a measurement of left ventricular end-diastolic pressure. An SvO2 is obtained through a blood draw from the yellow lumen of the PAC. A Low SvO2 can indicate that either body tissues are taking more oxygen from the blood as compensation for increased oxygen needs or are not receiving enough oxygen to begin with (CO is not high enough to meet the body’s demand). Therefore, SvO2 can be used to determine if CO and oxygen delivery is sufficient for the patient. SvO2 is the percentage of oxygen attached to the hemoglobin in the blood leaving the right ventricle.
This is a continuous waveform measurement. Whereas pulmonary artery diastolic pressure (PADP) is a measurement of the pressure in the PA during RV diastole. Pulmonary artery systolic pressure (PASP) is the pressure exerted by the right ventricle (RV) during systole on the PA. PAP is a reflection of cardiac heart pressures and is read as a systolic and diastolic number. CI is merely CO with consideration of the patient’s body surface area (BSA), and is, therefore, more accurate for clinical decision making. The only lab values needed to run a Fick is a mixed venous saturation (SvO2) and an arterial saturation. All of these numbers are collected and inserted into a Fick calculator which gives us CO and cardiac index (CI). With a PAC, CO is determined by obtaining an SvO2 level, the patient’s body surface area, a hemoglobin level, and an SpO2 reading. CO is the amount of blood pumped by the heart each minute and is simply heart rate multiplied by stroke volume (the amount of blood ejected with each beat). PACs allow for assessment of Cardiac Output (CO), Pulmonary Artery Pressure (PAP), Mixed venous oxygenation (SvO2), Pulmonary Artery Wedge Pressure (PAWP), and Central Venous Pressure (CVP) through blood draws and waveform analysis.
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