Cardiovascular calculations: Peter is wearing a cardiovascular monitoring device
ID: 3476027 • Letter: C
Question
Cardiovascular calculations: Peter is wearing a cardiovascular monitoring device during his rowing competition. He is at the 1000 meter mark (halfway through), and his device is reading the following data: PARAMETER Systolic pressure (aorta) Diastolic pressure (aorta) R-R interval Left ventricular EDV Left ventricular ESV Mean pulmonary artery pressure Right atrial pressure Left atrial pressure O2 consumption (whole body) O2 content of systemic arterial blood O2 content of pulmonary arterial blood VALUE 170 mm Hg 80 mm Hg 470 msec 180 mL 50 mL 21 mmHg 3 mm Hg 6 mmHg 1500 mL/min 0.20 mL O2/mL blood 0.11 mL O2/mL bloodExplanation / Answer
Mean arterial pressure (MAP) is the average pressure in an individual's arteries during the cardiac cycle. It is a time-weighted average; the ventricles spend only about 1/3rd of their type in pumping blood out and 2/3rd of their time in receiving it. Hence, averaging systolic and diastolic pressure would assign them equal weights and give an incorrect picture.
MAP is estimated by the average of systolic pressure and twice the diastolic pressure.
MAP = [SBP + 2 (DBP)]/3 = [170 + (2×80)]/3 = 110 mm Hg