Table 1: The effects of maintaining low central venous pressure during liver transplantation on clinical outcomes.

References Study Design Number of Patients per Group Target Value of CVP per Phase* Strategies to Maintain Low CVP Favorable Clinical Outcomes Unfavorable Clinical Outcomes Study Limitations
Schroeder et al. (2004) [5] Retrospective
analysis		 Low CVP group: 73
Normal CVP group: 78		 Preanhepatic and neohepatic phases: < 5 mmHg
Anhepatic phase: as low as possible		 Alpha-agonists (phenylephrine or norepinephrine)
Venodilator (nitroglycerin)
Opioid (Morphine)
Diuretic (Furosemide)		 Reduced transfusion rate Higher peak creatinine level
More frequent need for postoperative dialysis
Higher 30-day mortality
Lower mean arterial pressure during the anhepatic phase		 Patient allocation to groups according to transplant center (low CVP group from transplant center 1; normal CVP group from transplant center 2)
Higher proportion of critically ill patients in the normal CVP group
Insignificant difference in CVP between the groups during the preanhepatic phase; Significantly low CVP during the anhepatic phase in the normal CVP group compared to the low CVP group (assumed to be an error in data input); Average CVP values (10 to 12 mmHg) close to upper normal limits during the preanhepatic and neohepatic phases
Massicotte et al. (2006) [4] Prospective study combined with retrospective analysis Prospective low CVP group: 98
Historical control: 206		 Preanhepatic phase: approximately 60% of the baseline Restriction of volume infusion
Phlebotomy without volume replacement		 Reduced transfusion rate, blood loss, and 72-hour postoperative creatinine level - Use of historical controls
Short average duration of surgery (approximately 260 minutes) complicating universal application of the protocol to transplantation centers not reaching a learning curve plateau
Massicotte et al. (2008) [3]† Prospective study combined with retrospective analysis Prospective low CVP group: 300
Historical control: 206		 Preanhepatic phase: approximately 67% of the baseline Restriction of volume infusion
Phlebotomy without volume replacement		 Reduced transfusion rate, blood loss, and 72-hour and 1-year postoperative creatinine level
Higher final hemoglobin level		 - Use of historical controls
Short average duration of surgery (approximately 260 minutes) complicating universal application of the protocol to transplantation centers not reaching a learning curve plateau
Feng et al. (2010) [2] Prospective, randomized-controlled, parallel-group study Low CVP group: 43
Control group: 43		 Preanhepatic phase: < 5 mmHg or 60% of the baseline Restriction of volume infusion
Reverse Trendelenberg position
Somatostatin
Nitroglycerin		 Reduced transfusion rate
Lower levels of AST, ALT, TB, and lactate during the neohepatic phase		 Lower mean arterial pressure 2 hours after the surgery -
Cywinski et al. (2010) [32] Retrospective analysis Low CVP group: 56
High CVP group: 88		 Neohepatic phase: < 10 mmHg Discretion of the attending anesthesiologists - Slow rates of decrease in ALT and bilirubin levels between postoperative days 1 and 5 Significantly low BMI, short case duration, high preoperative platelet count, and high frequency of epinephrine use in the low CVP group
Wang et al. (2013) [30] Prospective, randomized-controlled, parallel-group study Low CVP group: 33
Control group: 32		 Approximately 60% of the baseline (the phase in which low CVP was maintained was not specified) Restriction of volume infusion
Trendelenberg position
Nitroglycerin
Furosemide		 Reduced transfusion rate and blood loss
Low incidence of pulmonary complications
Early weaning from mechanical ventilation		 - -

CVP: Central venous pressure; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; TB: Total bilirubin; BMI: Body mass index. *Preanhepatic phase: begins with surgical incision and ends with vascular exclusion and total hepatectomy of the native liver; Anhepatic phase: begins with the occlusion of vascular inflow to the native liver and ends with the reperfusion of a liver graft; Neohepatic phase: begins with the reperfusion of a liver graft. †By recruiting more patients in the prospective group from the previous study [4], the results of this study were created.