Splanchnic circulation in cardiac surgery
Author: Gårdebäck, Michael
Date: 1996-06-07
Location: Thoraxklinkernas aula, Plan U1, Karolinska sjukhuset
Time: 10.00
Department: Inst för klinisk vetenskap, intervention och teknik / Dept of Clinical Science, Intervention and Technology
Abstract
The studies addressed different techniques of monitoring hepatic and splanchnic blood flow (SBF) during open heart surgery. Calculations of gastric mucosal pH (pHi) using tonometry was performed in 72 patients, and the effect of dopaminergic stimulation on pH1 was studied in 33 patients.
Transesophageal echocardiography (TEE) for determination of hepatic venous flow (HVF) was used in 18 patients and the method was validated against indicator dilution technique with indocyanine green (ICG) in 10 patients. In 9 patients estimations of SBF by low-dose ethanol was validated against ICG.
Specific aims: (1) To measure SBF in cardiac surgery with ICG. (2) To study the effect of cardiopulmonary bypass on pH1 and to evaluate the possible effect of dopexamine on a postoperatively low pHi. (3) To evaluate the possible effects on pHi of low-dose dopexamine and dopamine when used for 24 hours as a prophylactic infusion and started directly after induction of anesthesia for cardiac surgery. (4) To estimate HVF with echo-Doppler during open heart surgery and to assess right heart dynamics by recordings of hepatic venous flow patterns. (5) To compare measurements of SBF with ethanol and ICG as indicators. (6) To validate echo-Doppler measurements of HVF against dye extraction estimations of total SBF by continuous ICG infusion, before and during CPB and by low-dose ethanol infusion before, during and after CPB.
Results: (I) SBF measured with ICG was 765 (s.e.m. 88) ml/min following induction of anesthesia and did not change during surgery and CPB. (2) An increase in pHi was noted during CPB (p<0.05) followed by a decrease compared to baseline after CPB. Dopexamine reduced pHi compared to the placebo group (p <0.05). (3) pHi and arterial pH did not differ between patients receiving dopexamine or dopamine versus control patients. Both the carbondioxide tension of arterial blood (PaCO2) and of the saline in the tonometer (PtonCO2) changed in parallel with a decrease during CPB and an increase after CPB. (4) HVF measured by TEE was unchanged during normothermic and reduced during hypothermic CPB. Six of 8 patients had a normal predominant systolic flow pattern in the hepatic vein before CPB. In the postoperative period 7 patients showed an abnormal predominant diastolic filling pattern. (5) A positive correlation (r=0.76, p < 0.01 was noted between SBF measured with ethanol and ICG. (6) The echo-Doppler measurements of HVF were on the average 46¡/o below those with ICG. There was no correlation between HVF measured with TEE and SBF measured with ICG.
Conclusions: The maintained splanchnic blood flow and the absence of signs of anaerobic metabolism, as measured with gastric tonometry, was indicative of a good perfusion technique during CPB. Dopexamine did not increase a postoperatively low pHi, and dopaminergic stimulation with dopexamine and dopamine initiated after anesthetic induction was withouteffect on pHi. The gastric mucosal pH and PtonCO2 were changed in parallel to arterial pH and PCO2. The hepatic venous flow pattern was altered after CPB indicating changes in the diastolic function of the right atrium and the right ventricle. Indicator dilution technique with ethanol did constitute an alternative to ICG in measuring SBF. The technique can be used without hepatic vein catheterization. Determination of HVF with echo-Doppler technique was not suitable to quantify SBF. The technique as applied in the study can not be recommended indetermining flow changes in the individual patient.
Transesophageal echocardiography (TEE) for determination of hepatic venous flow (HVF) was used in 18 patients and the method was validated against indicator dilution technique with indocyanine green (ICG) in 10 patients. In 9 patients estimations of SBF by low-dose ethanol was validated against ICG.
Specific aims: (1) To measure SBF in cardiac surgery with ICG. (2) To study the effect of cardiopulmonary bypass on pH1 and to evaluate the possible effect of dopexamine on a postoperatively low pHi. (3) To evaluate the possible effects on pHi of low-dose dopexamine and dopamine when used for 24 hours as a prophylactic infusion and started directly after induction of anesthesia for cardiac surgery. (4) To estimate HVF with echo-Doppler during open heart surgery and to assess right heart dynamics by recordings of hepatic venous flow patterns. (5) To compare measurements of SBF with ethanol and ICG as indicators. (6) To validate echo-Doppler measurements of HVF against dye extraction estimations of total SBF by continuous ICG infusion, before and during CPB and by low-dose ethanol infusion before, during and after CPB.
Results: (I) SBF measured with ICG was 765 (s.e.m. 88) ml/min following induction of anesthesia and did not change during surgery and CPB. (2) An increase in pHi was noted during CPB (p<0.05) followed by a decrease compared to baseline after CPB. Dopexamine reduced pHi compared to the placebo group (p <0.05). (3) pHi and arterial pH did not differ between patients receiving dopexamine or dopamine versus control patients. Both the carbondioxide tension of arterial blood (PaCO2) and of the saline in the tonometer (PtonCO2) changed in parallel with a decrease during CPB and an increase after CPB. (4) HVF measured by TEE was unchanged during normothermic and reduced during hypothermic CPB. Six of 8 patients had a normal predominant systolic flow pattern in the hepatic vein before CPB. In the postoperative period 7 patients showed an abnormal predominant diastolic filling pattern. (5) A positive correlation (r=0.76, p < 0.01 was noted between SBF measured with ethanol and ICG. (6) The echo-Doppler measurements of HVF were on the average 46¡/o below those with ICG. There was no correlation between HVF measured with TEE and SBF measured with ICG.
Conclusions: The maintained splanchnic blood flow and the absence of signs of anaerobic metabolism, as measured with gastric tonometry, was indicative of a good perfusion technique during CPB. Dopexamine did not increase a postoperatively low pHi, and dopaminergic stimulation with dopexamine and dopamine initiated after anesthetic induction was withouteffect on pHi. The gastric mucosal pH and PtonCO2 were changed in parallel to arterial pH and PCO2. The hepatic venous flow pattern was altered after CPB indicating changes in the diastolic function of the right atrium and the right ventricle. Indicator dilution technique with ethanol did constitute an alternative to ICG in measuring SBF. The technique can be used without hepatic vein catheterization. Determination of HVF with echo-Doppler technique was not suitable to quantify SBF. The technique as applied in the study can not be recommended indetermining flow changes in the individual patient.
Issue date: 1996-05-17
Publication year: 1996
ISBN: 91-628-2113-X
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