Question

An otherwise healthy 30 year old male is being observed in the Emergency Department for chest discomfort. Blood pressure is 140/95 mmHg, respiration rate of 24/minute. Temp 98.9 F. By cardiac monitor, heart rhythm is normal, with normal intervals. A normal QRS complex follows each P wave. A 6 second rhythm strip shows 8 QRS complexes. An ECG is normal. On echocardiogram, all cardiac chambers and heart valves are normal in appearance. Left ventricular end diastolic volume is 100 ml. Left ventricular end systolic volume is 40 ml. All calculations and units must be included in calculations for full credit.  Calculate heart rate. __________________________  Calculate stroke volume. __________________________  Calculate left ventricular ejection fraction. __________________________  Calculate cardiac output. __________________________  Calculate mean arterial pressure. _______________________

Answer 1

-->​​​​​​​​​​​​​​Calculation of heart rate:

Heart rate can be calculated by subtracting our age from the value 220. This value gives the average maximum heart rate of a person.

220 - Your age = Max. heart rate

As the patient's age is 30 years,

220 - 30 = 190 beats/min.

So, the patient's Heart rate = 190 beats/min

-->Calculation of stroke volume:

Stroke volume is calculated by subtracting end systolic volume from end diastolic volume.

SV = EDV - ESV

As the patient's end diastolic volume is 100 ml

end systolic volume is 40 ml

SV = 100-40 = 60 ml

So, the patient's stroke volume = 60 ml

-->Calculation of left ventricular ejection fraction:

Left ventricular ejection fraction is calculated by dividing stroke volume (volume of blood pumped from left ventricle) by end-diastolic volume (volume of blood collected at left ventricle).

LVEF = SV/EDV

= 60/100 = 0.6 = 60%

So, the patient's left ventricular ejection fraction = 60%

-->Calculation of cardiac output:

Cardiac output is the product of stroke volume and heart rate.

CO = SV × HR

  = 60 × 190 = 11400 ml = 11.4 liters

So, the patient's cardiac output = 11.4 liters

-->Calculation of mean arterial pressure:

Mean arterial pressure (MAP) is calculated by doubling diastolic pressure and adding the sum to systolic pressure and then, dividing the whole by 3.

MAP = Systolic pressure + (2 × diastolic pressure) ÷ 3

= 40 + (2 × 100) ÷ 3

= 240 ÷ 3 = 80 mm Hg

So, the patient's Mean arterial pressure = 80 mm Hg

Thank you!