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Platelet function and adrenoceptors during and after induced hypotension using nitroprusside
G V Dietrich1, M Heesen, J Boldt
1Department of Anaesthesiology and Intensive Care Medicine, Justus-Liebig-University, Giessen, Germany.
Anesthesiology
|December 1, 1996
Summary
Controlled hypotension with sodium nitroprusside reduced platelet aggregation and blood loss during surgery. This effect persisted post-operatively, unlike in control groups.
Area of Science:
- Anesthesiology
- Hematology
- Surgical Oncology
Background:
- Sodium nitroprusside-induced hypotension can reduce intraoperative blood loss.
- Endogenous catecholamines may influence platelet aggregation via adrenoceptors.
Purpose of the Study:
- To investigate the effect of controlled hypotension on platelet aggregation and blood loss.
- To assess the influence of sodium nitroprusside on platelet function post-surgery.
Main Methods:
- Forty patients undergoing nasal or sinus surgery were randomized into hypotension (A) and control (B) groups.
- Blood samples were collected pre-operatively, post-anesthesia, during surgery, and post-surgery.
- Platelet aggregation and alpha 2 receptor expression were measured.
Main Results:
- Epinephrine-induced and spontaneous platelet aggregation increased in controls but not in the hypotension group.
- Norepinephrine concentrations were higher in the hypotension group during surgery.
- Blood loss was significantly greater in the control group (379 ml) compared to the hypotension group (180 ml).
Conclusions:
- Controlled hypotension with sodium nitroprusside effectively reduces platelet aggregation and intraoperative blood loss.
- The anti-aggregatory effect persisted post-operatively, with no reactive increase observed.
- Potential mechanisms include nitroprusside's direct effect, augmented stress response, or reduced shear stress on platelets.