Hemodynamics in experimental hypernatremic dehydration with special reference to individual organ blood flow in shock and after rehydration.

Shock after hypernatremic dehydration in the mini-pig is characterized by low cardiac output but little reduction of arterial blood pressure. Maintenance of pressure is due to extensive arteriolar vasoconstriction in the splanchnic and renal vascular bed, as calculated from their markedly diminished blood flow. The expected preservation of flow to vital organs did occur in the brain and the adrenals, but not in the heart. Sufficient oxygen was probably provided by the elevated hematocrit. After 24 h, intravenous fluid therapy produced adequate rehydration as seen from the correction of azotemia, metabolic acidosis, and hypernatremia; only serum creatinine remained elevated. Although cardiac output increased, it did not reach the initial value. Blood flow to most organs was back to normal, but gastrointestinal and particularly renal blood flow remained diminished.