Assessment of the Effects of Pressors on Graft Blood Flow After Free Tissue Transfer Surgery

Study Overview
=================
Brief Summary
-----------------
Following surgery to remove tumours of the head and neck, patients undergo reconstruction with free flaps - tissue that is taken from elsewhere in the body and given a new blood supply by attaching it to vessels in the neck. Following this type of surgery, patients often need medication to maintain their blood pressure in the intensive care unit. The effect of these drugs on the transplanted tissues is unknown. This study investigates the effects of four commonly used drugs on free flap perfusion.

Detailed Description
-----------------
The optimal sympathomimetic drug to support blood pressure without adverse vasoconstriction of free flap circulation remains unknown. This study examined the effects of four agents (epinephrine, norepinephrine, dobutamine and dopexamine) on free flaps following resection of head and neck cancer. Twenty five patients were recruited to the study. Each patient received an infusion of the four drugs in a random order with an intervening washout period between drugs, at four infusion rates. Continuous free flap skin blood flow monitoring was performed using laser Doppler velocimetry, with a second sensor on normal skin acting as a control. Global cardiovascular variables were monitored using the LiDCO Rapid pulse contour analysis system.

Official Title
-----------------
An Assessment of the Effects of Pressors on Graft Blood Flow After Free Tissue Transfer Surgery: A Randomised Study

Conditions
-----------------
Oral Cancer, Head and Neck Cancer, Free Flap, Hypotension

Intervention / Treatment
-----------------
* Drug: Epinephrine
* Drug: Norepinephrine
* Drug: Dobutamine
* Drug: Dopexamine


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients undergoing free tissue transfer surgery at the John Radcliffe Hospital wih planned post-operative admission to the intensive care unit. Exclusion Criteria: Pregnancy Weight >100kg Contraindications to pressor infusions Overnight ventilation not indicated

Ages Eligible for Study
-----------------
Minimum Age: 17 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Pressors<br>Epinephrine, Norepinephrine, Dobutamine, Dopexamine | Drug: Epinephrine<br>* 0.2mcg/kg/min maximum infusion; to increase mean arterial pressure by 30mmHg<br>Drug: Norepinephrine<br>* Maximum infusion of 0.2mcg/kg/min, to increase mean arterial pressure by 30mmHg<br>Drug: Dobutamine<br>* Maximum infusion rate of 8mcg/kg/min to increase mean arterial pressure by 30mmHg<br>Drug: Dopexamine<br>* Maximum infusion rate of 5mcg/kg/min to increase mean arterial pressure by 30mmHg<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Absolute change in transfer function (flap vascular resistance) after pressor infusion. |  | Post infusion (at 4 hours) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Relative change in transfer function after pressor infusion compared with normal tissue. |  | Post infusion (at 4 hours) | 
| Change in flap flow after pressor infusion |  | Post infusion (at 4 hours) | 
| Differences in frequency spectrum of skin blood flow between flaps and normal tissue before and after pressor infusion. |  | Post infusion (at 4 hours) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
norepinephrine, noradrenaline, epinephrine, adrenaline, dobutamine, dopexamine, inotrope, pressor, sympathomimetic, free flap, transplantation, free tissue transfer, microsurgery, survival