Abstract
Refractory hypotension is frequent in very low-birth weight infants, whose hypothalamic-pituitary-adrenal axis has been suggested to be immature. The objective of the present study was to evaluate basal cortisol and 17-a-OH-progesterone in the first 36 h of life in preterm infants with and without refractory hypotension (mean arterial blood pressure below the lower limit for gestational age throughout the study despite aggressive volume expansion and use of vasopressors). Thirty-five infants with £30 weeks of gestation and a birth weight £1250 g, with no postnatal use of corticosteroid or death in the first 48 h were studied. Mean arterial pressure was measured every 4 h during the first 48 h. Cortisol and 17-a-OH-progesterone were determined at 12 and 36 h and patients were divided into refractory hypotensive (N = 15) and control (N = 20) groups. The groups were not different regarding type of delivery, use of prenatal corticosteroid, requirement of mechanical ventilation, use of vasopressor drugs, morphine, fentanyl, prophylactic indomethacin, and mean sample timing. Although refractory hypotensive newborns were more immature, were smaller, suffered more deaths after 48 h of life and had a higher SNAPPE-2 score, their cortisol and 17-a-OH-progesterone levels were not different from controls at 12 h and at 36 h. The increase of cortisol in newborns with refractory hypotension 36 h after birth was significantly higher than in controls. Despite the fact that refractory hypotensive very low-birth weight neonates were submitted to a very stressful condition, their cortisol and 17-a-OH-progesterone levels were similar to controls.
Highlights
A significant proportion of very lowbirth weight (VLBW) infants may present hypotension that is refractory to both volume expanders and vasopressor drugs [1,2]
Hanna et al [8] have reported that very preterm newborn infants have a normal pituitary response to ovine corticowww.bjournal.com.br tropin-releasing hormone and a normal adrenal response to ACTH, recent studies have shown that those with refractory hypotension have an immature hypothalamic-pituitary-adrenal (HPA) axis and a decreased response to the ACTH test compared to VLBW infants with no refractory hypotension at the end of the first week of life [1,2]
Hypotension is an early manifestation in VLBW infants, usually in the first 48 h of life, and is associated with increased mortality and central nervous system morbidity in preterm infants [10,11,12]
Summary
A significant proportion of very lowbirth weight (VLBW) infants may present hypotension that is refractory to both volume expanders and vasopressor drugs [1,2]. Many of these infants have been shown to respond to the use of corticosteroids, with normalization of arterial blood pressure and a reduction of the dose of vasopressor drugs [3,4,5,6,7]. An adrenal response to a stressful situation like severe arterial hypotension resistant to inotropic treatment is expected in VLBW infants with an intact HPA axis [13]
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