[Effect of controlled hypotension using sodium nitroprusside on platelet aggregation].
OBJECTIVE
To determine the influence of sodium nitroprusside (SNP) on platelet aggregation when this agent is used to induce hypotension during surgery.


METHODS
Spontaneous platelet aggregation (SPA) determined by impedance measurement and induced platelet aggregation (IPA) determined by turbidimetry were studied in 30 subjects scheduled for elective ear, nose or throat surgery. Fifteen patients in the SNP group (SNPG) received SNP in doses adjusted to maintain a mean arterial pressure of 50 mmHg. Another 15 patients who did not receive SNP served as controls.


RESULTS
SPA increased progressively in both groups. The greatest increase occurred after anesthetic induction (control group +172%, SNPG +48%); the highest level recorded was reached on the morning of the first day after surgery (control group +215%, SNPG +46%). IPA decreased after anesthetic induction (control group -21%, SNPG -40%) and stayed down throughout surgery. IPA was higher on the first morning after surgery than before the operation (control group +35%, SNPG +2%). SPA was significantly higher 60 minutes after start of surgery than before surgery in the control group; IPA and SPA were likewise higher in these patients the morning after surgery.


CONCLUSIONS
Platelet aggregation increases during surgery and in the immediate postoperative period. This increase is attenuated when SPA is given to induce hypotension. SPA should be determined by measurement of impedance in whole blood when the nature of platelet aggregation during surgery is being studied, given that early increases in IPA can be masked as a result of the low sensitivity of turbidimetry.
Heesen
M
M
Departamento de Anestesiología y Cuidados Intensivos, Universidad Justus-Liebig, Giessen, Alemania.
Dietrich
G V
GV
Wirth
R
R
Ballesteros
M
M
Welters
I
I
Hempelmann
G
G
D001778:Blood Coagulation Disorders / Q000517:prevention & control; D016063:Blood Loss, Surgical / Q000517:prevention & control*; D001800:Blood Specimen Collection; D006801:Humans; D007023:Hypotension, Controlled; D007430:Intraoperative Care; D007432:Intraoperative Period; D009300:Nasal Septum / Q000601:surgery; D009391:Nephelometry and Turbidimetry; D009599:Nitroprusside / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010979:Platelet Function Tests / Q000379:methods; D011184:Postoperative Period; D013048:Specimen Handling
D010975:Platelet Aggregation Inhibitors; D009599:Nitroprusside
Influencia de la hipotensión controlada con nitroprusiato sódico sobre la agregación plaquetaria.