Targeting the amount of fluid given to measurements of the patients own fluid status during major abdominal surgery has been linked with improved speed of recovery of gut function and reduced length of hospital stay, mortality and complications.

Pleth variability index (PVI) offers a noninvasive, risk and pain free alternative to more invasive forms of monitoring to direct how much fluid to give.

The study aims primarily to measure and compare how much fluid is given when guided by PVI compared to the established technique; oesophageal doppler during major abdominal surgery.

The study will compare 40 patients undergoing major elective abdominal surgery. Patients will receive intraoperative fluid guided by either oesophageal doppler or PVI. Secondarily, the study will examine biochemical markers, length of hospital stay and how frequently complications occur

Inclusion Criteria:

• Major abdominal surgery
• Anaerobic Threshold >11 ml O2/kg/min
• VE/VCO2 <34 OR
• Low risk according to Consultant anaesthetist

Exclusion Criteria:

• Patients age less than 18
• Patient refused consent
• Patient unable to give consent
• Patient has had <24hrs to consider the Patient information Sheet
• Contraindication to Doppler Probe being inserted
• Emergency Procedure
• Patient has a ASA Grade 5
• Patient is receiving dialysis treatment
• Patient has a known hypersensitivity to hydroxyethyl starch or gelatin solutions
• Patients with renal failure with oliguria or anuria - not related to hypovolaemia
• Patients with a previously diagnosed dysrhythmia
• Patients who weight >100kg