The purpose of this study is to determine if vasopressin and nitroglycerin in combination will affect hepatic hemodynamics, in the setting of liver surgery.

The patients in this study (undergoing elective liver resection) will be anesthetized according to routine practice in our hospital. A radial arterial catheter and a central venous catheter will be inserted, as well as a femoral arterial catheter for Picco monitoring. After the dissection phase, catheters will be inserted in the portal and hepatic veins by the surgeon. Base line data (HR, CVP, MAP, CO from thermodilution, portal and hepatic venous pressure, blood gases from radial artery, vena cava superior, hepatic vein and portal vein) will be obtained twice, with 10 minutes of steady state in between. An infusion of vasopressin 4,8 U/h will then be started and continued for 20 minutes. Data will be collected again, and an infusion of nitroglycerine (to a target of MAP 60 mmHg) will be added. After 5 minutes of steady MAP 55-65, the last set of data is collected. 12 Patients will be recruited, and the total data collection is estimated to be completed and assessed after six to nine months.

Inclusion Criteria:

• Patients within ASA-class I-II scheduled for open liver resection

Exclusion Criteria:

• ASA-class III and IV, more than 2 medications for hypertension, BMI > 35, technical difficulties with insertion av catheters, extensive surgery.

No plans of sharing IPD