Cardiovascular function during acute normovolemic hemodilution (ANH) with hydroxyethyl starch or Ringer's lactate

Purpose

Our objective was to study the cardiovascular function in canines that underwent progressive normovolemic hemodilution using two different solutions.

Methods

Under general anesthesia using etomidate and isoflurane, and with controlled ventilation, 2 animals were submitted to progressive ANH with either hydroxyethyl starch (HES, n = 10) or Ringer's lactate (RL, n = 10) solution on a ratio of 1:1 or 1:3, respectively. A Swan-Ganz catheter, echocardiography and eletrocardiography were used in the assessment of the cardiovascular function. The hemodilution was monitored with sequential measurements (20 min) of the concentration values of hemoglobin and hematocrit, while the cardiovascular function for the different variables were studied. Data were evaluated through ANOVA (P < 0.05).

Results

The final hemoglobin concentration for the HES was 4.0 (± 1.2)g/dl and 3.0 (± 1.0) g/dl for the RL. Heart rate and blood pressure did not change. The cardiac output and cardiac index increased in both groups during the hemodilution procedure; however, the RL group data had a lower value than was statistically significant at the end of the study period. The systemic and pulmonary vascular resistance decreased in both groups. The pulmonary capillary wedge pressure and central venous pressure reached higher values in both groups during ANH.

Conclusion

The study demonstrated that the cardiovascular variables deteriorated along with the reduction hemoglobin; nevertheless, the echocardiography data obtained would suggest that the use of HES allowed better cardiac contractility during prolonged periods of time over in lower levels of hemoglobin.