[Changes in whole blood ionized magnesium concentration during cardiac surgery employing St. Thomas' cardioplegic solution].
BACKGROUND
Although there is growing evidence to suggest that magnesium supplementation to patients undergoing cardiac surgery is beneficial, the way to administer magnesium is not established. Moreover in Japan St Thomas' cardioplegic solution, containing a high level of magnesium is widely used and the effect of such magnesium-rich cardioplegic solutions on blood magnesium concentration has not been well defined.


METHODS
We measured ionized magnesium concentrations (iMg) during cardiac surgery employing St Thomas' solution. Patients were divided into four groups. Group 1 patients were adults and group 2 were children, both of whom received St. Thomas' solution. Group 3 patients underwent cardiopulmonary bypass but did not receive any cardioplegic solution. Group 4 patients underwent off-pump coronary artery bypass grafting.


RESULTS
In cardioplegia group (group 1 and 2) iMg was higher than the normal reference range at periods of rewarming, immediately postbypass, and at the end of the operation. iMg at immediately postbypass was related to the total amount of cardioplegic solution. In non-cardioplegia group (group 3 and 4) progressive decrease of iMg was observed throughout the operation.


CONCLUSIONS
Because magnesium in cardioplegic solutions has substantial effect on perioperative iMg, it is crucial to measure iMg to avoid overdose of magnesium when magnesium-rich cardioplegic solutions are employed.
Department of Anesthesia, Showa General Hospital, Tokyo 187-8510.
Kyung-ho
KH
Chang
Masahiko
M
Bougaki
Ryou
R
Kubota
Kumiko
K
Tsubaki
Hideki
H
Matsuo
Kazuo
K
Hanaoka
D000293:Adolescent; D000328:Adult; D000368:Aged; D001639:Bicarbonates / Q000737:chemistry; D002122:Calcium Chloride / Q000737:chemistry; D006348:Cardiac Surgical Procedures; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007477:Ions; D008274:Magnesium / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control; D011189:Potassium Chloride / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013613:Tachycardia, Ectopic Junctional / Q000517:prevention & control
D001639:Bicarbonates; D007477:Ions; C041711:St. Thomas' Hospital cardioplegic solution; D012965:Sodium Chloride; D011189:Potassium Chloride; D008274:Magnesium; D002122:Calcium Chloride