Blood magnesium concentration and dopamine or dobutamine infusion demand in patients during CABG (coronary artery bypass grafting) with normovolemic haemodilution.
It is well known that magnesium (Mg) plays an essential role in cardiac protection. Mg has many beneficial effects on the myocardium and cardiac function, e.g. it improves contractility and reduces the number of cardiac arrhythmia episodes. The inotropically positive effects of Mg are interesting and worth stressing. High blood Mg concentration may result in an increase in cardiac contraction strength, which may be important for haemodynamic stabilization, and thus it is likely to decrease the demand for dopamine and dobutamine infusions. However, the exact determination of correlation between blood Mg concentrations and dopamine or dobutamine infusion demand is still unknown. The aim of the study was to assess the demand for dopamine or dobutamine infusion in relation to changes in blood magnesium concentrations in patients undergoing CABG (Coronary artery bypass graft) with extracorporeal circulation and normovolemic haemodilution. The study included 20 male patients, aged 53-70 (61.1 +/- 6.9) who underwent general anaesthesia and coronary artery bypass grafting (CABG) with extracorporeal circulation (ECC) and normovolemic haemodilution (NH) due to stable angina pectoris. The patients were retrospectively divided into three groups: A--patients who did not receive dopamine or dobutamine infusion, B--those receiving only D infusion in the doses dependent on their clinical state and C--those receiving DB infusion in the doses dependent on their clinical state. Mg was measured in 7 stages: 1) just before anaesthesia after the radial artery cannulation, 2) during normovolemic haemodilution and ECC, 3) immediately after surgery, 4) in the evening of the surgery day, 5) in the morning of the lst postoperative day, 6) in the evening of 1st postoperative day, 7) in the morning of the 2nd postoperative day. The spectrophotometric methods were used to determine Mg. The CABG procedure resulted in a decrease in Mg. Its level returned to normal in the evening of surgery day. The NH caused a similar Mg decrease in groups A, B and C, but these significantly low values of Mg were observed only in stage 2. There was no correlation between blood Mg concentrations and dopamine or dobutamine infusion demand.


CONCLUSIONS
1) The CABG procedure resulted in decreased blood magnesium concentrations. 2) The Mg changes do not correlate with dopamine or dobutamine infusion demand.
Pasternak
K
K
Department of Medical Chemistry, Feliks Skubiszewski Medical University of Lublin, Poland. kazimierz.pasternak@am.lublin.pl
Wrońska
J
J
Dabrowski
W
W
Sztanke
M
M
D000368:Aged; D001810:Blood Volume; D002316:Cardiotonic Agents / Q000008:administration & dosage; D001026:Coronary Artery Bypass; D004280:Dobutamine / Q000008:administration & dosage*; D004298:Dopamine / Q000008:administration & dosage*; D005112:Extracorporeal Circulation; D006438:Hemodilution; D006801:Humans; D007262:Infusions, Intravenous; D008274:Magnesium / Q000097:blood*; D008297:Male; D008875:Middle Aged
D002316:Cardiotonic Agents; D004280:Dobutamine; D008274:Magnesium; D004298:Dopamine