Altered interstitial fluid space dynamics and postresuscitation hypertension.

Hypertensin occurred 24 to 48 hours after resuscitation in 35 of 86 injured patients, who had combined systolic and diastolic hypertensin (150/100 mmHg) for six or more consecutive hours. Plasma volume (PV), RBC volume, extracellular fluid (ECF) volume by the inulin dilution technique, renal plasma flow, glomerular filtration rate, and peripheral renin levels were measured in hypertensive and nonhypertensive patients an average of 40 hours after injury. The hypertensive patients had an average mean arterial pressure (MAP) of 114 mmHg, compared with 95 mmHg in the nonhypertensive patients. The RBC volume and ECF were comparable for both groups, whereas PV was increased in the hypertensive patients (3.6 L vs 3.3 L). Calculated interstitial fluid space (IFS) volume was greater in the nonhypertensive patients, as was the ratio PV/IFS. The MAP in both groups correlated directly with PV/IFS and serum albumin concentrations, and inversely with peripheral renin concentrations. This suggests that postresuscitative hypertension is not due to fluid overload but rather to the fluid maldistribution related to altered IFS compliance as reflected by the increased PV/IFS.