Intraoperative Considerations for Liver Transplantation in Portopulmonary Hypertension
Patients with portopulmonary hypertension and mean pulmonary artery pressure ≥35 mmHg require specialized intraoperative hemodynamic monitoring with pulmonary artery catheterization and transesophageal echocardiography, combined with immediately available pulmonary vasodilators to prevent right ventricular failure during transplantation. 1, 2, 3
Mandatory Intraoperative Monitoring
Invasive Hemodynamic Monitoring
Pulmonary artery catheterization (PAC) must be placed for continuous monitoring of pulmonary artery pressures, cardiac output, and systemic vascular resistance throughout the procedure. 1 This allows real-time assessment of right ventricular function and immediate detection of acute pressure elevations.
Transesophageal echocardiography (TOE) should be available for immediate direct assessment of cardiac structures, ventricular function, regional wall motion abnormalities, left ventricular filling status, and right ventricular function. 1, 2 TOE provides critical visualization of right ventricular strain and function that cannot be obtained from PAC alone.
Critical Hemodynamic Parameters to Monitor
Continuously track mean pulmonary artery pressure, pulmonary vascular resistance, cardiac output, and right ventricular preload throughout all surgical phases. 2, 3 The anhepatic phase and reperfusion are particularly high-risk periods for acute pressure spikes.
Monitor transpulmonary gradient (mean PAP minus pulmonary artery occlusion pressure) to distinguish true portopulmonary hypertension from volume overload or left ventricular dysfunction. 4
Pulmonary Vasodilator Management
Immediately Available Agents
Inhaled nitric oxide and/or intravenous epoprostenol must be immediately available in the operating room for rapid administration if pulmonary artery pressures acutely rise. 2, 3 These rapidly acting vasodilators can prevent right ventricular decompensation during critical surgical phases.
Continue all preoperative pulmonary vasodilator therapy (endothelin receptor antagonists, phosphodiesterase-5 inhibitors, prostacyclin analogues) throughout the perioperative period without interruption. 5, 6 Discontinuation risks acute hemodynamic decompensation.
Intraoperative Vasodilator Strategy
For patients on parenteral prostacyclin therapy preoperatively, maintain continuous infusion throughout surgery with backup delivery systems in case of line complications. 2
Have protocols established for escalating vasodilator therapy if mean pulmonary artery pressure exceeds 45 mmHg or right ventricular dysfunction develops intraoperatively. 3
Prevention of Right Ventricular Failure
Avoiding Acute Pressure Elevations
The primary intraoperative goal is preventing right ventricular failure from acutely elevated pulmonary artery pressures or sudden increases in right ventricular preload. 3 This requires meticulous attention during reperfusion when sudden volume shifts occur.
Avoid factors that increase pulmonary vascular resistance: hypoxia, hypercarbia, acidosis, hypothermia, and excessive positive end-expiratory pressure. 2 These can precipitate acute right heart failure in patients with limited pulmonary vascular reserve.
Volume Management
Maintain careful fluid balance to avoid both hypovolemia (which reduces right ventricular preload excessively) and volume overload (which increases right ventricular afterload). 3, 4 Central venous pressure should be monitored but interpreted in context of pulmonary artery pressures.
Recognize that cirrhotic patients have baseline hyperdynamic circulation with extremely low peripheral vascular resistance and compensatory increased cardiac output. 1 This baseline state complicates volume management during transplantation.
Anesthetic Considerations
Ventilation Strategy
Maintain normocapnia and avoid hypoxia, as both hypercarbia and hypoxia cause pulmonary vasoconstriction that can acutely worsen pulmonary hypertension. 2
Use lung-protective ventilation strategies with moderate tidal volumes to minimize effects on pulmonary vascular resistance while maintaining adequate oxygenation.
Inotropic Support
Have inotropic agents readily available to support right ventricular contractility if dysfunction develops, but avoid agents that significantly increase pulmonary vascular resistance. 3
Milrinone may be particularly useful as it provides both inotropic support and pulmonary vasodilation. 2
Critical Surgical Phases
Reperfusion Period
The reperfusion phase carries highest risk for acute hemodynamic instability with sudden increases in venous return and potential for acute right ventricular volume overload. 3 Intensify monitoring and have vasodilators prepared for immediate administration.
Communicate closely with surgical team about timing of reperfusion to allow anesthetic preparation and optimization of hemodynamics before this critical moment. 2
Anhepatic Phase
- During the anhepatic phase, reduced venous return may temporarily improve right ventricular loading conditions, but this creates risk for acute decompensation when circulation is restored. 3
Common Pitfalls and Caveats
Distinguishing True Portopulmonary Hypertension
Elevated mean pulmonary artery pressure ≥35 mmHg can occur from high cardiac output states or increased pulmonary venous volume rather than true elevated pulmonary vascular resistance. 7, 4 Intraoperative hemodynamics must distinguish these, as outcomes differ dramatically.
Patients with elevated mean PAP but normal pulmonary vascular resistance (<240 dynes/s/cm⁻⁵ or <3 Wood units) from high flow states have excellent outcomes and do not require the same intensive vasodilator management. 7, 4
Contraindications That Should Have Been Identified Preoperatively
Mean pulmonary artery pressure >45 mmHg despite maximal medical therapy represents an absolute contraindication to liver transplantation. 5 If such patients reach the operating room, the procedure should be aborted as mortality risk is prohibitive.
Right ventricular dysfunction on preoperative assessment is also an absolute contraindication. 5 These patients should not proceed to surgery.
Medication Interactions
Be aware that beta-blockers (often used for variceal bleeding prophylaxis) worsen hemodynamics and exercise capacity in portopulmonary hypertension patients. 5 Consider discontinuation or dose reduction perioperatively in consultation with hepatology.
Avoid anticoagulation in patients at increased bleeding risk despite pulmonary hypertension. 5 The bleeding risk from portal hypertension and surgical procedure outweighs anticoagulation benefits.
Specialized Anesthetic and Surgical Expertise Required
Liver transplantation in portopulmonary hypertension requires specialized anesthetic sophistication and surgical expertise beyond routine transplant procedures. 3 Centers without this experience should consider transferring such patients to high-volume centers with established protocols.
Ensure availability of cardiac anesthesiologists or anesthesiologists with advanced training in pulmonary hypertension management for these cases. 2