Systemic-to-pulmonary artery pressure ratio as a predictor of patient outcome following liver transplantation

Table 1 Patient demographics and surgical characteristics

	Age (yr)	Gender (F:M ratio)	MELD (score)	OR duration (min)	Crystalloid (mL)	Colloid (mL)	PRBC (units)	FFP (units)
Group 1 (n = 66)	55.6 ± 8.6	24:42 (36%)	18.7 ± 8.4	400.9 ± 43.5	5804 ± 2824	1440 ± 972	3.3 ± 3.7	2.8 ± 3.0
Group 2 (n = 25)	58.9 ± 5.4	7:18 (28%)	16.3 ± 6.9	427.9 ± 63.3	6086 ± 3424	1607 ± 626	3.9 ± 3.1	4.0 ± 4.6
P-value	0.081	0.189	0.204	0.081	0.690	0.428	0.473	0.148

Data are shown as mean ± SD. P value was obtained using paired t-test for all parameters except gender. The 1-tail exact binomial calculation with probability value of 0.5. Group 1 (n = 66): Patients with MAP/mPAP ratio increase during anhepatic period; Group 2 (n = 25): Patients with MAP/mPAP ratio decrease or no change during anhepatic period. MELD: Model For End-Stage Liver Disease score; OR duration: Anesthesia time from induction to ICU transfer; Crystalloid: Amount of intraoperative normal saline; Colloid: Amount of intraoperative 5% Albumin; PRBC: Packed red blood concentrate; FFP: Fresh frozen plasma; MAP/mPAP: Mean systemic-to-pulmonary artery pressure.

Table 2 Mean systemic-to-pulmonary artery pressure ratio and cardiac index, measured at several times during the liver transplant: Baseline (30 min after incision), preanhepatic (1 h before inferior vena cava cross-clamp), anhepatic (15 min before reperfusion), neohepatic (15 min after reperfusion), and 1 h neohepatic (1 h after reperfusion)

	Group 1	Group 2	P-value
	MAP/mPAP increase during anhepatic period (n = 66)	MAP/mPAP no change or decrease during anhepatic period (n= 25)
MAP/mPAP baseline	3.32 ± 0.734	4.13 ± 1.191	0.185
% change preanhepatic	0.278 ± 1.276	0.184 ± 1.268	0.754
% change anhepatic	2.892 ± 1.827	-0.088 ± 1.137	< 0.01a
% change neohepatic	0.206 ± 1.411	-0.688 ± 1.325	< 0.01a
% change 1 h neohepatic	0.098 ± 0.828	-0.611 ± 1.373	< 0.01a
CI baseline	4.111 ± 1.229	4.214 ± 0.961	0.879
% change preanhepatic	0.039 ± 0.790	-0.204 ± 0.832	0.200
% change anhepatic	-1.606 ± 1.018	-1.188 ± 1.082	0.089
% change neohepatic	-0.327 ± 1.316	-0.058 ± 1.231	0.378
% change 1 h neohepatic	0.335 ± 1.106	0.454 ± 1.038	0.643
ET
min	967 ± 1361	1719 ± 1933	0.040a
h	16.1 ± 22.7	28.7 ± 32.2
Median (min)	540	1045
LOS ICU (d)	3.9 ± 4.4	12.1 ± 19.2	< 0.01a
Median (d)	2	6
LOS hospital (d)	12.0 ± 12.5	26.3 ± 33.2	< 0.01a
Median (d)	8	11

% change is calculated as difference from value to baseline value; data are shown as mean ± SD, and median value for ET and LOS. P value was obtained using paired t-test.

^aP < 0.05. ET (duration of postoperative endotracheal intubation): Minutes from ICU arrival to extubation to supplemental oxygen; LOS ICU: Length of stay in intensive care unit; LOS total: Time from ICU arrival to hospital discharge; MAP/mPAP: Mean systemic-to-pulmonary artery pressure ratio; CI: Cardiac index.

Table 3 Vasopressor use

	Group 1	Group 2	P-value
Vasopressor use frequency	MAP/mPAP increase during anhepatic period (n = 66)	MAP/mPAP no change or decrease during anhepatic period (n = 25)
No vasopressor use	14	5	0.624
Low dose vasopressor use	39	12	0.341
High dose vasopressor use	13	8	0.214

Following medications are intraoperatively available: Norepinephrine (NE), Epinephrine (EPI), Vasopressin (V), Dopamine or Phenylephrine (PHE). Based on intraoperative documentation at 15 min before reperfusion (anhepatic measurement of MAP/mPAP ratio). The patients were sorted into three different categories: No vasoactive medication use; low dose vasoactive medication use (NE < 0.05 mcg/kg per minute or EPI < 0.03 mcg/kg per minute or V < 0.03 units/min or PHE < 0.1 μg/kg per minute) and high dose vasoactive medication use (NE ≥ 0.05 μg/kg per minute, EPI ≥ 0.03 μg/kg per minute, V ≥ 0.03 units/min or any vasopressor combination). Data are shown as patient number receiving vasopressor therapy at the anhepatic measurement point (15 min before reperfusion). P value was obtained using χ² test. A P-value for < 0.05 was set for statistical significance. MAP/mPAP: Mean systemic-to-pulmonary artery pressure.