Effects of Nitroglycerin Versus Labetalol on Tissue Perfusion During Deliberate Hypotension
Effects of Nitroglycerin Versus Labetalol on Tissue Perfusion During Deliberate Hypotension
Deliberate hypotension is used to provide bloodless field during endoscopic sinus surgery;
 however, hypotension might impair perfusion of vital organs. The aim of this work is to
 compare the impact of nitroglycerin and labetalol on peripheral perfusion when used for
 induction of deliberate hypotension
Hypotensive anesthesia is associated with the risk of reduced tissue perfusion. The usual
 target mean arterial pressure during deliberate hypotension is 50- 65 mmHg; however, the
 status of peripheral perfusion under this target is not well investigated. Nitroglycerin and
 Labetalol are commonly used drugs to achieve deliberate hypotension. Nitroglycerin is a
 direct vasodilator and its main action is through venodilation, while labetalol combines a
 selective α1 and non selective beta-adrenergic blocking activity. Both drugs were previously
 compared during deliberate hypotension with regard to surgical field quality and blood loss.
 No study to date compared the effects of both drugs on peripheral perfusion when used for
 induction of deliberate hypotension. The Peripheral Perfusion Index (PPI) is the ratio
 between pulsatile and non-pulsatile components of peripheral circulation. Measurement of PPI
 is based on analysis of the pulse oximetry signal. PPI showed increasing popularity as a non
 invasive monitor of peripheral perfusion. Serum lactate is another frequently used marker of
 global tissue perfusion.The aim of this study is to compare the influence of nitroglycerin
 and labetalol on tissue perfusion when used for induction of deliberate hypotension during
 FESS operations. Tissue perfusion will be evaluated using PPI and serum lactate as markers of
 peripheral and global tissue perfusion respectively.
Inclusion Criteria:

 -  Adult male or female patients

 -  18-45 years

 -  ASA physical status I-II

 -  scheduled for FESS operations

 Exclusion Criteria:

 -  uncontrolled hypertension

 -  cerebrovascular disorders

 -  coagulation disorders

 -  cardiovascular diseases

 -  renal impairment

 -  liver impairment

 -  history of allergic reaction to any of the study medications