The pressure field as a methodology for fluid management and red cell preservation during cardiac surgery

Table 2 Regression coefficients of pre-operative and post-operative hemoglobin concentration, as visualised in Fig. 2

Method	Slope	intercept	R²	P
Conventional	0.36 ± 0.03	36 ± 5	0.212	< 0.0001
Pressure field	1.11 ± 0.13	− 22 ± 18	0.491	< 0.0001
Conventional—female	0.07 ± 0.07	72 ± 9	0.002	0.291
Pressure field—female	0.65 ± 0.55	23 ± 64	0.047	0.275
Conventional—male	0.41 ± 0.04	30 ± 6	0.234	< 0.0001
Pressure field—male	1.06 ± 0.16	− 21 ± 21	0.444	< 0.0001

A slope of ‘1’ indicates no change in hemoglobin between the beginning and completion of surgery; a zero slope indicates a constant final hemoglobin, irrespective of the initial value. Correlation is shown for the combined male and female groups, and the groups are then classified by both method and sex. P-values < 0.05 are indicated in bold type

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