Low Hematocrit Impairs Gastric Mucosal Co2 Removal During Experimental Severe Normovolemic Hemodilution

Abstract

de-Figueiredo LF. Low hematocrit impairs gastric mucosal co 2 removal during experimental severe normovolemic hemodilution. CLINICS. 2006(5):445-52. OBJECTIVE: The net effects of acute normovolemic hemodilution with different hemoglobin levels on splanchnic perfusion have not been elucidated. The hypothesis that during moderate and severe normovolemic hemodilution, systemic and splanchnic hemodynamic parameters, oxygen-derived variables, and biochemical markers of anaerobic metabolism do not reflect the adequacy of gastric mucosa, was tested in this study. METHODS: Twenty one anesthetized mongrel dogs (16 ± 1 kg) were randomized to controls (CT, n = 7, no hemodilution), moderate hemodilution (hematocrit 2 5% ± 3%, n = 7) or severe hemodilution (severe hemodilution, hematocrit 15% ± 3%, n = 7), through an isovolemic exchange of whole blood and 6% hydroxyethyl starch, at a 20 mL/min rate, to the target hematocrit. The animals were followed for 120 min after hemodilution. Cardiac output (CO, L/min), portal vein blood flow (PVF, mL/min), portal vein-arterial and gastric mucosa-arterial CO 2 gradients (PV-artCO 2 and PCO 2 gap, mm Hg, respectively) were measured throughout the experiment. RESULTS: Exchange blood volumes were 33.9 ± 3.3 and 61.5 ± 5.8 mL/kg for moderate hemodilution and severe hemodilution, respectively. Arterial pressure and systemic and regional lactate levels remained stable in all groups. There were initial increases in cardiac output and portal vein blood flow in both moderate hemodilution and severe hemodilution; systemic and regional oxygen consumption remained stable largely due to increases in oxygen extraction rate. There was a significant increase in the PCO 2-gap value only in severe hemodilution animals. CONCLUSION: Global and regional hemodynamic stability were maintained after moderate and severe hemodilution. However, a very low hematocrit induced gastric mucosal acidosis, suggesting that gastric mucosal CO 2 monitoring may be useful during major surgery or following trauma.

Blood Tranfusion in Critically Ill Patients: State of the Art

“…Perin D et al, in a recent paper, confirmed the findings that global and regional stability were maintained after moderate and severe hemodilution. 77 However, this work showed that severe hemodilution was related to increased intestinal-arterial PCO 2 , suggesting that monitoring gastric mucosal CO 2 may be useful during major surgery or following trauma.…”

Role of acute hemodilution in blood transfusion rate in patients submitted to scoliosis surgery: observational retrospective study

“…Increase in the extraction rate compensating low oxygen delivery works during normovolemia only. 3. , 4.…”