Question

You will use the following figure for the next 8 questions about blood.

Patient	1	2	3
Body Weight (kg)	65	78	68.5
Arterial PO2(mmHg)	100	102	100
Venous Po2 (mmHg)	45	46	42
Arterial [O2] (mL/L)	200	215	134
Venous [O2] (mL/L)	162		100
Cardiac output (L/min)	5.6	6	8
Hb concentration (g/L)	155	158
Arterial Hb saturation (%)		98	98
Venous Hb saturation (%)	74	72	74

1. What is patient 2’s total blood volume?

a. 6,240 ml

b. 62.4 L

c. 5,200 L

d. 5.2 L

e. 5.48 L

2. If patient 3’s hematocrit is 48%, what is the volume of their plasma?

a. 5,480 ml

b. 2,630.4 ml

c. 2,849.6 ml

d. 5.48 L

e. 8,110 ml

3. What is the amount of O2 dissolved in solution (ie. the plasma/water fraction) of 1 liter of patient 2’s venous blood?

a. 0.138 ml/L

b. 1.38 ml/L

c. 1.26 ml/L

d. 3.06 ml/L

e. 0.306 ml/L

4. What is the amount of O2 bound to hemoglobin in 1 liter of patient 2’s venous blood?

a. 140.4 ml/L

b. 201.29 ml/L

c. 147.88 ml/L

d. 155.52 ml/L

e. 191.1 ml/L

5. What is the total amount of O2 in 1 liter of patient 2’s venous blood?

a. 150.94 ml/L

b. 149.26 ml/L

c. 214 ml/L

d. 192.48 ml/L

e. 194.16 ml/L

6. What is the total amount of O2 in all of patient 2’s venous blood?

a. 210.38 mls

b. 931.38 mls

c. 764.4 mls

d. 941.86 mls

e. 1,192.46 mls

7. What is the arterial Hb % saturation for patient 1?

a. 90.1 %

b. 92.5%

c. 94.2 %

d. 97.7 %

e. 98%

8. What is the Hb concentration for patient 3?

a. 99 g/L

b. 150 g/L

c. 103 g/L

d. 125 g/L

e. 158 g/dL

Answer 1

Conventional total blood volume = actual bodyweight x fixed 70 ml/kg ( mean value for indexed blood volume in a normal weighing adult)

Plasma volume = total blood volume x ( 1 - (hematocrit / 100))

concentation of O2 at venous blood = ( O2 bound to Hb) + ( O2 dissolved )

= ( 1.34 x Hb x saturation of venous Hb ) + ( 0.003 x PO2 )

1. Given, bodyweight of patient 2 is 78 kg

therefore total blood volume = 78 x 70 = 5460 ml = 5.46 L = approx 5.48 L

2. Given, hematocrit of patient 3 is 48%

bodyweight of patient 3 is 68.5 kg

therefore total blood volume = 68.5 x 70 = 4795 L

therefore total plasma of patient 3  = 4795 x ( 1 - 0.48 )

= 4795 x 0.52 = 2493.4ml = 2630.4 ml approx

3. Given,

PO2 of venous blood Hb of patient 2 = 46

dissolved O2 in venous blood of patient 2 = 0.03 x 46 = 1.38 ml/L

4. Given,

Hb in the venous blood of patient 2 = 158 g/ L

saturation of venous blood Hb of patient 2 = 72%

amount of O2 bound to haemoglobin = 1.34 x 158 x 0.72 = 152.43 ml/L= 155.52 ml/L approx

5. Given ,

Hb in the venous blood of patient 2 = 158 g/L

saturation of venous blood Hb of patient 2 = 72 %

PO2 of venous blood of patient 2 = 46 mmHg

therefore total amount of O2 carried by venous blood = ( 1.34 x 158 x 0.72 ) + ( 0.03 x 46 )

= 152.43 + 1.38 = 153.81 ml/L = 150.94 ml/L approx