Postocclusive Reactive Hyperaemia of Cutaneous Blood Flow in Premature Newborn Infants

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Abstract
Beaufort-Krol, G. C. M., Suichies, H. E., Aarnoudse, J. G., Okken, A., Jentink, H. W. and Greve, J. (Departments of Obstetrics and Paediatrics, University Hospital, Groningen, and Department of Applied Physics, Enschede, The Nether- lands). Postocclusive reactive hyperaemia of cutaneous blood flow in premature new- born infants. Acta Paediatr Scand Suppl 360: 20, 1989. Reactive hyperaemia, which occurs after a period of arterial occlusion is the result of an autoregulatory mechanism, involving local factors and autonomic nerve system control. To determine this autoregulatory mechanism in cutaneous blood flow in premature newborns we measured the cutaneous reactive hyperaemia response after a 1 min occlusion, using a diode laser Doppler flowmeter applied to the skin. Twenty- four infants with a gestational age ranging from 25 to 37 weeks and a postnatal age of 0.3 to 72 days were studied. The reactive hyperaemia response is described by the parameters maximal cutaneous blood flow (V,,,), the time to reach maximal flow (t,,,), the time taken for blood flow to return to baseline following V,,, (tend) and the % increase in cutaneous blood flow above preocclusional level (overshoot). A cutaneous reactive hyperaemia response could be elicited in all infants. Following occlusion the V,,, was 2 640 ? 1 050 mV (mean t SD), the t,,, was 7.6 ? 3.9 sec (mean t SD), the tend was 35.6 t 14.6 sec (mean ? SD) and the overshoot was 74.6 2 34 % (mean 2 SD). A negative correlation was found between hematocrit and t,,, (r= -0.62, p < 0.01). No influence of postconceptional age, postnatal age, skin and rectal tempera- ture, incubator temperature, weight, and transcutaneous oxygen tension on the reac- tive hyperaemia parameters could be found. We conclude that reactive hyperaemia of cutaneous blood flow can be elicited in premature newborn infants irrespective of postconceptional age, and that the hematocrit is inversely related to the time to reach