Superiority of Blood Over Saline Resuscitation From Hemorrhagic Shock: A 31P Magnetic Resonance Spectroscopy Study

Abstract

ObjectiveTo study the relation between blood and saline administration, postresuscitation hematocrit (Hct) level, and metabolic recovery after hemorrhagic shock. Summary Background DataIt is generally believed that crystalloid can be substituted, in whole or in part, for blood during resuscitation of hemorrhagic shock. This is based on the belief that Hct can be safely reduced but should not fall below a critical level. MethodsMale rats weighing 200 g were subjected to an isobaric hemorrhagic shock at a mean arterial pressure of 30 mmHg for 14 minutes, after which they were randomized to one of three resuscitation regimens. Control group (n = 36) were resuscitated by return of all shed blood. Mid-Hct (n = 39) and low-Hct (n = 60) groups were depleted of one third and one half of their circulating blood volumes, respectively, and were resuscitated with three times that volume of normal saline. Skeletal muscle intracellular energetics and pH were measured serially using 31p magnetic resonance spectroscopy at baseline, during shock, and after resuscitation. Arterial blood was sampled at the same time points. The number of surviving animals in each group at 24 hours was recorded. ResultsAfter resuscitation, surviving rats in the low-Hct group demonstrated a greater consumption of high-energy phosphocreatine stores than did the other groups (control = 0.479 ± 0.003, mid-Hct = 0.465 ± 0.004, low-Hct = 0.457 + 0.007, mean ± standard error of the mean; p < 0.01 low-Hct vs. other groups by analysis of variance). The rats that received saline resuscitation developed a relative intracellular acidosis (control = 7.29 + 0.02, midHct = 7.25 ± 0.02, low-Hct = 7.23 ± 0.02; p < 0.05 controls vs. other groups by analysis of variance). At 24 hours, the death rates were significantly different among the groups: control = 1 of 36 rats (2.8%), mid-Hct = 6 of 39 (15.4%), and low-Hct = 14 of 60 (23.3%) (p < 0.05 by chi square analysis). ConclusionThe oxygen-carrying capacity of resuscitation fluid has an important impact on intracellular metabolism and outcome.653

Magnetic Resonance Spectroscopy for Evaluation of Liposome-Encapsulated Hemoglobin as a Resuscitation Fluid

“…In order to obtain statistically significant (p<0.01 or 0.05) differences in the results, it may be necessary to either enhance the severity of shock (from 40% to ~70% bleeding) or to prolong the duration of shock. The typical signatures of hemorrhagic shock like a high mortality in the non-resuscitated group [44, 47] and a significant drop in ATP level (expected only after complete PCr depletion) were absent in our study. This suggests that with a 40% blood withdrawal the shock was not of a severe nature.…”

Major venous injury and large volume crystalloid resuscitation: A limb threatening combination

“…Additionally, if venous ligation is required, venous hypertension develops, leading to increased vascular resistance, decreased arterial flow, and worse interstitial edema from capillary leak. 10 Patients in hemorrhagic shock can have profound ischemic changes to the lower extremity resulting from inadequate distal perfusion followed by reperfusion injury. This is particularly evident in the skeletal muscle that makes up the bulk of the soft tissue of the lower extremity.…”

Tissue Energetics as Measured by Nuclear Magnetic Resonance Spectroscopy During Hemorrhagic Shock

“…By following changes in the NMR phosphorus signal, a real-time measurement of ATP levels, as well as other important energetic variables, can be examined during shock and resuscitation (10). This allows an investigator to understand the magnitude of the energetic deficiency that a shock state can impose on various tissues.…”