3. (1) A Fick technique is used to measure the heart output. If the O, consumpti

Question

3. (1) A Fick technique is used to measure the heart output. If the O, consumption is 1.42 liter measured in 5 minutes, the arterial O2 concentration is 0.22 ml/ml and venous O2 concentration is 0.16ml/ml. What is the patient's cardiac output? (2) A rapid-injection method is used to measure the average flow rate. If the injected mass of indicator is 50 mg. The measured concentration curve is shown in Fig. 8.2 in the text. If the area under the curve (from time B to time E or infinite without recirculation) is 0.54 mg-s/ml, what is the average flow rate in unit L/min?

Explanation / Answer

1) Cardiac Output CO is given by following formula

CO = VO2 / (Ca - Cv )

Where

VO2 = Oxygen consumption in ml /min = 1.42*1000 / 5 = 284 ml /min

Ca = Oxygen concentration of arterial blood = 0.22 ml/ml

Cv = Oxygen concentration of venous blood = 0.16 ml/ml

Therefore putting these values in formula we get

CO = 284 / (0.22 - 0.16 )

CO = 284 / 0.06

CO = 4733.33 ml/min                                  ..................1

This is the required value of cardiac output.

2) data is insufficient.

   graph is not provided

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