Decreases in hemoglobin and hematocrit may signal degree of hemorrhagic shock: retrospective evaluation in a dog model.

Objective: Data were extracted from preexisting published studies and evaluated retrospectively to compare lactate and base deficit values at baseline and posthemorrhage with changes in corresponding hemoglobin (Hb) and Hct measurements to assess any association of such changes with severity of hemorrhage over time. To understand the goal, the objective of this study was to demonstrate statistical changes in laboratory values as described above.

Methods: Previous prospectively designed experiments on 120 mixed-breed dogs were conducted. Various parameters, including Hb and Hct, lactate concentration, and base deficit, were extracted from the previously mentioned experiments. To validate this retrospective study, subset data on heart rate and arterial pressure were compared. In a subset analysis, 60 experiments were extracted to compare baseline mean arterial pressure to posthemorrhagic values to prove the validity of this model. Published studies were evaluated retrospectively to compare lactate and base deficit values at baseline and posthemorrhage.

Results: Arterial pressure is lowest posthemorrhage, increases, then stabilizes. Baseline Hb averaged 15.1 g/dL and Hct 43.4%, and posthemorrhage values averaged 12.1 g/dL (Hb) and 35.3% (Hct). Significant differences were observed for both Hb (3.0 g/dL difference; P < .001) and Hct (8.3% difference; P < .001) posthemorrhage. Lactate significantly increased (2.1; P < .001), and base deficit significantly decreased (5.2; P < .001).

Conclusions: The data collected retrospectively validated the model for significant hypotension. It was then possible to evaluate whether Hb and Hct may accurately predict the degree of hemorrhage. In this model, both Hb and Hct decreased posthemorrhage significantly, although the actual change in Hb and Hct posthemorrhage was modest. Lactate concentration increased, and base deficit decreased.

Clinical relevance: The data suggest that Hb, Hct, lactate, and base deficit should be studied to see if they may have a potential role in guiding resuscitation decisions.