Effects of Nitroglycerin Versus Labetalol on Tissue Perfusion During Deliberate Hypotension
Condition: Tissue Perfusion; Deliberate Hypotension; Sinus Endoscopic Surgery
MeSH terms: Hypotension
Study type: Interventional
Phase: Phase 4

Summary: 
      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
    

Detailed description: 
      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.
    

Intervention name(s): Nitroglycerin; Labetalol
Intervention type(s): Drug; Drug
Intervention description(s): Nitroglycerin is a direct vasodilator and its main action is through venodilation. Nitroglycerin will be diluted by adding 3 mL (3 mg) to 47 mL normal saline in a 50 mL syringe and will be infused after endotracheal intubation with a starting dose of 0.5 mL/Kg/ hr to have a starting dose of 0.5 μg/Kg/min. The rate of nitroglycerin infusion will be 0.5-2 μg /kg/min .The infusion rate will be finely adjusted to maintain MAP around 55-65mmHg or till reaching adequate surgical field {defined as surgical field score (SFS) <3}.; Labetalol is an α and β - adrenergic receptors competitive antagonist. Labetalol will be diluted by adding 10 mL (50 mg) to 40 mL normal saline in a 50 mL syringe and will be infused after endotracheal intubation with a starting dose of 0.5 mL/Kg/ hr. The rate of Labetalol infusion will be 0.5-2 mg/kg/h.The infusion rate will be finely adjusted to maintain MAP around 55-65mmHg or till reaching adequate surgical field {defined as surgical field score (SFS) <3}.
Intervention MeSH terms: Labetalol; Nitroglycerin
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Supportive Care
Keywords: Deliberate hypotension; Nitroglycerin; Labetalol; Peripheral perfusion