[Plasma vasopressin in premature infants on mechanical ventilation].

A systematic study has been undertaken to improve the understanding of water regulation in premature babies who are artificially ventilated. Thirty nine premature babies, 16 normal (Group N, GA 31.4 weeks, B/W 1622 g) and 23 with respiratory distress syndrome who were ventilated with or without continuous positive pressure (Group V, GA 31 weeks, BW 1505 g) have been studied. Plasma osmolalities were the same in both groups (284 and 282 mosM/Kg H2O) but there were significant differences (p less than 0.001) between the urine osmolalities N = 150.6 +/- 19.6 V = 294 +/- 25.9 mosM/Kg H2O) and the plasma ADH levels of the two groups (N = 2.9 +/- 0.4 pg/ml, V = 12.2 +/- 2.4 pg/ml). There was a significant correlation between the urine osmolality and the plasma ADH level but not between plasma osmolality and the plasma ADH level. Several hypotheses can be proposed but none are satisfactory.