Summary of patients included in the study
| Variable . | Overall . | Males . | Females . | P difference between genders . |
|---|---|---|---|---|
| N | 31 | 16 | 15 | |
| Age (years) | 40.5 [37.1, 43.8] | 42.3 [37.0, 47.5] | 38.5 [34.1, 43.0] | .2585 |
| Weight (kg) | 62.3 [56.9, 67.6] | 67.3 [61.6, 72.9] | 56.9 [47.8, 66.1] | .0462 |
| Height (cm) | 159.6 [155.4, 163.9] | 166.3 [161.1, 171.4] | 153.0 [147.7, 158.4] | .0006 |
| Days since previous transfusion | 22 [20, 24] | 22 [18,25] | 23 [20, 25] | .5701 |
| Number of red cell units transfused | 2.8 [2.6, 3.1] | 2.9 [2.5, 3.2] | 2.8 [2.4, 3.2] | .7835 |
| Transfusion volume (mL/kg)* | 11.9 [10.7, 13.2] | 11.0 [9.3, 12.7] | 12.9 [11.0, 14.8] | .1273 |
| Estimated patient blood volume (L)† | 3.91 [3.59, 4.22] | 4.46 [4.14, 4.78] | 3.36 [2.97, 3.74] | .0001 |
| Estimated milliliters transfused per liter blood volume† | 196.5 [175.2, 217.9] | 171.3 [143.4, 197.2] | 221.0 [190.9, 251.2] | .0122 |
| Mean age of transfused unit (days) | 16.1 [14.2, 18.0] | 15.7 [13.0, 18.4] | 16.5 [13.4, 19.6] | .6865 |
| Variable . | Overall . | Males . | Females . | P difference between genders . |
|---|---|---|---|---|
| N | 31 | 16 | 15 | |
| Age (years) | 40.5 [37.1, 43.8] | 42.3 [37.0, 47.5] | 38.5 [34.1, 43.0] | .2585 |
| Weight (kg) | 62.3 [56.9, 67.6] | 67.3 [61.6, 72.9] | 56.9 [47.8, 66.1] | .0462 |
| Height (cm) | 159.6 [155.4, 163.9] | 166.3 [161.1, 171.4] | 153.0 [147.7, 158.4] | .0006 |
| Days since previous transfusion | 22 [20, 24] | 22 [18,25] | 23 [20, 25] | .5701 |
| Number of red cell units transfused | 2.8 [2.6, 3.1] | 2.9 [2.5, 3.2] | 2.8 [2.4, 3.2] | .7835 |
| Transfusion volume (mL/kg)* | 11.9 [10.7, 13.2] | 11.0 [9.3, 12.7] | 12.9 [11.0, 14.8] | .1273 |
| Estimated patient blood volume (L)† | 3.91 [3.59, 4.22] | 4.46 [4.14, 4.78] | 3.36 [2.97, 3.74] | .0001 |
| Estimated milliliters transfused per liter blood volume† | 196.5 [175.2, 217.9] | 171.3 [143.4, 197.2] | 221.0 [190.9, 251.2] | .0122 |
| Mean age of transfused unit (days) | 16.1 [14.2, 18.0] | 15.7 [13.0, 18.4] | 16.5 [13.4, 19.6] | .6865 |
Arithmetic mean [95% confidence interval]; P calculated from 2-sample t test.
Assuming each bag contains 260 mL red cells (Australian Red Cross Blood Service red cell unit mean volume = 259 ± 23 mL).50
Nadler’s formula for total blood volume (TBV): men, TBV (mL) = 604 + (367 × height3 [m3]) + (32.2 × weight [kg]); women, TBV (mL) = 183 + (356 × height3 [m3]) + (33.1 × weight [kg]).