Reference no: EM133638239
In the lecture, we learned the relation between heart rate (HR), stroke volume (SV), and cardiac output (CO). Actually, the stroke volume can be further expressed as the difference between the end-diastolic volume (EDV) and the end-systolic volume (ESV) of the heart chambers, i.e. SV = EDV - ESV. We can understand the EDV corresponds to the largest volume of heart chambers after the diastolic (blood filling) phase, while the ESV corresponds to the smallest volume of heart chambers after the systolic (blood pumping-out) phase. Suppose we measure an adult's heart rate at rest HR = 75 bpm, end-diastolic volume EDV = 142 mL/beat, and end-systolic volume ESV = 47 mL/beat.
1. We define the ejection fraction EF = SV/EDV × 100%, which is a measure of the fraction of blood ejected by the heart chambers during the contraction or ejection phase. Please compute the ejection fraction of this adult.
2. Please compute the cardiac output of this adult.
3. We define the cardiac index (CI) based on the ratio of cardiac output (CO) and body surface area (BSA) to relate the heart performance to the size of the individual, i.e. CI = CO/BSA.
The body surface area can be estimated through DuBois formula, i.e. BSA = 0.007184 × W0.425 × H0.725, where W is the body weight with the unit of kg, H is the body height with the unit of cm, leading to the unit of BSA as m2. Suppose we measure this adult's weight as 75 kg, and height as 170 cm. Please compute the cardiac index of this adult.
4. The normal range of cardiac index at rest is 2.6 - 4.2 L/(min·m2). Based on your computation, is the adult's CI in the normal range?