Table 2

Use of central-peripheral temperature difference (CPTd), capillary refill time (CRT), mean and systolic blood pressure (BP) to predict low superior vena cava flow (< 41 ml/kg/min) in preterm infants < 30 weeks gestation. Combined observations and conditional likelihood ratios in first 24 hours

	Normal flow	Low flow	Total
*Mean blood pressure ⩽ gestation in weeks.
CPTd
< 2°C	74	15	89
⩾ 2°C	33	10	43
Total	107	25	132
CRT
< 3 seconds	249	25	274
3–3.9 seconds	49	15	64
⩾ 4 seconds	13	16	29
Total	311	56	367
Systolic BP
⩾ 48 mm Hg	89	4	93
40–47.9 mm Hg	81	9	90
< 40 mm Hg	81	41	122
Total	251	54	305
Mean BP
⩾ 30 mm Hg	193	22	215
< 30 mm Hg	58	32	90
Total	251	54	305
> Gestation	220	38	258
⩽ Gestation*	31	16	47
Total	251	54	305