Fluid compartments in hemorrhaged rats after hyperosmotic crystalloid and hyperoncotic colloid resuscitation

Postresuscitation organ failure may be associated with detrimental changes in body fluid compartments. We measured how shock and resuscitation acutely alters the interstitial, cellular, and plasma compartments in different organs. Nephrectomized, anesthetized rats were bled to 50 mmHg mean arterial pressure for 1 h, followed by 60 min of resuscitation to restore blood pressure using 0.9% normal saline (NS,n = 10), 7.5% hypertonic saline (HS,n = 8), 10% hyperoncotic albumin (HA, n = 8), or 7.5% hypertonic saline and 10% hyperoncotic albumin (HSA, n = 7). A 2-h 51Cr-EDTA distribution space estimated extracellular fluid volume (ECFV), and a 5-min 125I-labeled albumin distribution space measured plasma volume (PV). Total tissue water (TW) was measured from wet and dry weights; interstitial fluid volume (ISFV) and cell water were calculated. NS resuscitation required 7 times more fluid (50.9 +/- 7.7 vs. 8.6 +/- 0.7 for HA, 5.9 +/- 0.4 for HS, and 3.9 +/- 0.5 ml/kg for HSA), but there were no differences between solutions in whole animal PV, ECFV, or ISFV. Fluid shifts within tissues depended on resuscitation solution and type of tissue. TW was significantly reduced by hypertonic saline groups in heart, muscle, and liver (P < 0.05). ISFV was significantly reduced by HA groups in the skin. In all tissues, mean cell water in groups receiving HS was smaller; this was significant for heart, lung, muscle, and skin. In conclusion, 1) HS solutions mobilize fluid from cells while expanding both PV and ISFV, and 2) TW and cellular water increase with both isotonic crystalloids and hyperoncotic colloids in many tissues.