Management Algorithm for PAH Crises
In PAH crisis, immediately admit to ICU, initiate inhaled nitric oxide as first-line pulmonary vasodilator, start dobutamine for inotropic support, and prepare for continuous IV epoprostenol escalation if the patient fails to stabilize—with veno-arterial ECMO as rescue therapy for refractory right ventricular failure. 1
Immediate Recognition and ICU Admission
Recognize PAH crisis by the constellation of high heart rate, low systolic blood pressure, low urine output, and rising lactate levels—these indicate imminent right ventricular failure requiring immediate ICU admission. 1 The mortality rate for PAH patients admitted to ICU reaches 41%, making early recognition and aggressive intervention critical. 1
Critical Hemodynamic Monitoring
- Establish central venous access immediately for direct measurement of central venous pressure and central venous oxygen saturation. 2
- Monitor vital signs, urine production, central venous oxygen saturation, and blood lactate levels continuously. 1
- Central venous oxygen saturation <60% combined with rising lactate and absent urine production signals imminent right heart failure requiring immediate therapy escalation. 1
- The fundamental hemodynamic goal is maintaining systemic vascular resistance greater than pulmonary vascular resistance at all times. 2, 1
Pharmacologic Management Algorithm
Step 1: Pulmonary Vasodilators (First-Line)
Initiate inhaled nitric oxide immediately as the preferred first-line pulmonary vasodilator. 2, 1 Inhaled nitric oxide decreases pulmonary vascular resistance, improves cardiac output, has a short half-life allowing rapid titration, and critically does not affect systemic vascular resistance. 2, 1
- Start inhaled nitric oxide at standard dosing and titrate to hemodynamic response. 2
- If inhaled nitric oxide is unavailable, consider inhaled iloprost as an alternative. 3
Step 2: Inotropic Support
Start dobutamine as the preferred inotrope for all hypotensive PAH crisis patients. 2, 1 Dobutamine has neutral or beneficial effects on pulmonary vascular resistance and a shorter half-life than milrinone, allowing better control when hypotension risk exists. 2, 1, 3
- Initiate dobutamine to maintain adequate cardiac output and systemic perfusion. 1
- Consider vasopressin at replacement doses to offset potential drops in systemic vascular resistance, particularly in septic patients or those with liver disease. 2, 3
Step 3: Escalation to IV Epoprostenol
If the patient fails to stabilize on inhaled nitric oxide and dobutamine, immediately initiate continuous IV epoprostenol. 1, 3
- Start epoprostenol at 2 ng/kg/min and increase in increments of 2 ng/kg/min every 15 minutes or longer until dose-limiting effects occur or tolerance is established. 1
- IV epoprostenol has demonstrated mortality reduction in high-risk PAH patients. 1, 3
- Critical caveat: Patients on prostacyclin analogues placed on ECMO may develop pronounced systemic vasodilation requiring temporary dose reduction. 4
Step 4: Weaning Strategy
- When weaning from inhaled nitric oxide, start or restart a phosphodiesterase-5 inhibitor as replacement therapy to prevent rebound pulmonary hypertension. 2
Respiratory Management
Maintain oxygen saturation >90% at all times to prevent hypoxia-induced increases in pulmonary vascular resistance. 2, 1, 3
Mechanical Ventilation (If Required)
- Avoid mechanical ventilation if possible, as positive intrathoracic pressure reduces venous return and worsens right ventricular failure. 3
- If ventilation becomes necessary, employ a low tidal volume strategy (approximately 6 mL/kg lean body weight) to minimize increases in right ventricular afterload. 2, 1, 3
- Keep peak pressures <30 cmH₂O and limit positive end-expiratory pressure to ≤10 cmH₂O when possible. 2, 1
- Avoid permissive hypercapnia as acidosis acutely increases pulmonary vascular resistance. 2, 1
Fluid Management
Optimize fluid balance with IV diuretics, as volume overload worsens right ventricular function. 1, 3 Diuretics are indicated in PAH patients with signs of right ventricular failure and fluid retention. 5
Mechanical Circulatory Support
For patients with PAH crisis, low cardiac output, or right ventricular failure despite optimal medical therapy, initiate veno-arterial ECMO as a bridge to recovery or transplantation. 2, 1, 6
- Upper-body ECMO configuration allows for daily physical therapy and ambulation, avoiding complications of immobility and invasive mechanical ventilation. 6
- All three patients in one series using extubated, nonsedated upper-body ECMO were extubated within 24 hours of ECMO initiation. 6
- Consider additional mechanical circulatory support options for left ventricular unloading if needed, such as intra-aortic balloon pump or Impella. 2
Post-Crisis Monitoring
All PAH patients must be admitted to ICU/CCU for at least 24 hours of monitoring after stabilization, as major cardiovascular complications often manifest 1-2 days following the acute event. 1
Critical Pitfalls to Avoid
- Never allow pulmonary vascular resistance to exceed systemic vascular resistance, which results in right ventricular ischemia. 2
- Avoid betablockers in PAH patients, as they worsen right ventricular function. 3
- Do not use non-selective systemic vasodilators that cause systemic hypotension without reducing pulmonary pressure. 3
- Riociguat combined with phosphodiesterase-5 inhibitors (sildenafil) is contraindicated due to hypotension risk. 3
- Avoid using static central venous pressure values alone to guide fluid therapy without considering dynamic parameters. 2
- For intubation, consult an experienced cardiac anesthesiologist and use fiberoptic awake intubation to avoid overstimulation of sympathetic drive, which increases pulmonary vascular resistance. 2