Hyperosmotic sodium salts reverse severe hemorrhagic shock: other solutes do not.

Severe hemorrhage in pentobarbital-anesthetized dogs (25 mg/kg) is reversed by intravenous NaCl (4 ml/kg, 2,400 mosmol/l, 98% long-term survival). This paper compares survival rates and hemodynamic and metabolic effects of hypertonic NaCl with sodium salts (acetate, bicarbonate, and nitrate), chlorides [lithium and tris(hydroxymethyl)aminomethane (Tris)], and nonelectrolytes (glucose, mannitol, and urea) after severe hemorrhage (44.5 +/- 2.3 ml/kg blood loss). Sodium salts had higher survival rates (chloride, 100%; acetate, 72%; bicarbonate, 61%; nitrate, 55%) with normal stable arterial pressure after chloride and nitrate; near normal cardiac output after sodium chloride; normal acid-base equilibrium after all sodium salts; and normal mean circulatory filling pressure after chloride, acetate, and bicarbonate. Chlorides and nonelectrolytes produced low survival rates (glucose and lithium, 5%; mannitol, 11%; Tris, 22%; urea, 33%) with low cardiac output, low mean circulatory filling pressure, and severe metabolic acidosis. Plasma sodium, plasma bicarbonate, mean circulatory filling pressure, cardiac output, and arterial pressure correlated significantly with survival; other parameters, including plasma volume expansion or plasma osmolarity, did not. It is proposed that high plasma sodium is essential for survival.

Hypertonic resuscitation from severe hemorrhagic shock: patterns of regional circulation.

Severe blood loss can be reverted to normal circulatory function and indefinite survival by a small volume of 2,400 mOsm/liter NaCl (7.5%). This response requires functioning cervical vagal trunks at the time of hypertonic injection. Other equally hypertonic solutes (glucose, mannitol) are ineffective. This paper examines the effects of hypertonic (2,400 mOsm/liter) NaCl (7.5%) and glucose (50%) on femoral, mesenteric, splanchnic, renal, and coronary circulations. Hypertonic NaCl was given to dogs with intact or blocked vagi. Femoral flow was measured in innervated or denervated hindlimbs. Hemorrhage severely restricted both innervated and denervated femoral flows. Hypertonic glucose and NaCl, vagi blocked, redilated both femoral territories. Hypertonic NaCl, intact vagi, redilated denervated femoral vasculature but severely restricted innervated flow. Renal, mesenteric, total splanchnic, and coronary flows were restricted by hemorrhage and undistinguishable redilated by glucose or NaCl, blocked or intact vagi. It appears therefore that hypertonic NaCl induces permanent survival, partly because of its ability to elicit a pulmonary reflex, which induces muscular/cutaneous precapillary constriction. This shunts essentially required flow into the viscera, which are unspecifically vasodilated by hypertonicity.