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.