pituitrin and Pneumothorax

The release of vasopressin (AVP) was assessed by measuring urinary excretion of the hormone in ten neonates who had an acute and symptomatic pneumothorax in the first three days after birth. AVP excretion rose significantly (paired t analysis) after the pneumothorax occurred. When apparent re-expansion of the lungs occurred after treatment, excretion of AVP returned to prepneumothorax levels within eight to 16 hours. If the pneumothorax persisted or worsened. AVP excretion remained elevated. Urine osmolality rose significantly (paired t analysis) after pneumothorax, presumably in response to the increased AVP levels. Two of the ten infants had hyponatremia in the period studied, while in a state of sodium balance. It was concluded that AVP release is increased after a pneumothorax occurs. This increase is apparently not due to osmoregulatory requirements. Fluid intake in these infants may need adjustment to prevent an inappropriate positive water balance.

Topics: Drinking; Humans; Hyponatremia; Infant, Newborn; Infant, Newborn, Diseases; Osmolar Concentration; Pneumothorax; Respiration, Artificial; Urine; Vasopressins

Nine episodes of the syndrome of inappropriate antidiuretic hormone secretion occurred in five newborn infants following atelectasis or pneumothorax. All infants had pre-existing lung disease and were being treated with positive pressure ventilation. The mean interval between acute atelectasis or pneumothorax and the development of diagnostic hyponatremia, hypo-osmolal serum, hyperosmolal urine, and oliguria was 13.4 hours. Fluid restriction and removal of the triggering event resulted in resolution of the abnormalities within 1.5 to 4 days. Infants who develop atelectasis or pneumothorax should be evaluated for the subsequent occurrence of SIADH; the administration of a water load to them may result in dilutional hyponatremia, for which fluid restriction, not sodium infusion, is the proper therapy.

Topics: Acute Disease; Humans; Infant, Newborn; Infant, Newborn, Diseases; Osmolar Concentration; Pneumothorax; Pulmonary Atelectasis; Sodium; Syndrome; Vasopressins