What is the management of a pulmonary hypertension crisis in an emergency setting?

Pulmonary Hypertension Crisis Management in Emergency

In a pulmonary hypertension crisis, immediately avoid hypoxia and acidosis through careful respiratory management, maintain systemic vascular resistance greater than pulmonary vascular resistance using vasopressors (preferably dobutamine or vasopressin), and initiate pulmonary vasodilators such as inhaled nitric oxide while preparing for possible ECMO if the patient deteriorates despite optimal medical therapy. 1

Immediate Priorities: The ABCs of PH Crisis

Respiratory Management - Avoid Intubation When Possible

• Hypoxia and acidosis are the primary triggers that worsen pulmonary vascular resistance and precipitate right ventricular failure 1
• Optimize oxygenation and ventilation non-invasively if at all possible, as positive pressure ventilation can precipitate cardiovascular collapse 1, 2
• If intubation is unavoidable, use careful ventilator settings to minimize positive end-expiratory pressure and avoid hyperinflation that increases right ventricular afterload 1
• Maintain normocapnia or mild hypocapnia, as hypercarbia dramatically increases pulmonary vascular resistance 1

Hemodynamic Assessment - Know Your Numbers

• Place a central venous line immediately to measure central venous pressure and mixed venous oxygen saturation, as volume status in PH patients is notoriously difficult to assess clinically 1
• Non-invasive estimates of volume status are unreliable and misleading in this population 1
• A pulmonary artery catheter can be useful but is not required in the emergency setting 1

Vasopressor and Inotrope Selection - The Critical Decision

The Golden Rule: SVR Must Exceed PVR

The fundamental principle is maintaining systemic vascular resistance (SVR) greater than pulmonary vascular resistance (PVR) to prevent right ventricular ischemia 1

• Unlike the left ventricle, the right ventricle receives coronary perfusion during both systole and diastole 1
• When systolic pulmonary artery pressure exceeds systolic systemic arterial pressure during systole, right ventricular ischemia occurs 1
• This means systolic blood pressure targets should be higher than in non-PH patients 1

Preferred Agents

• Dobutamine is the preferred inotrope due to its neutral or beneficial effects on PVR and shorter half-life compared to milrinone 1, 3
• Vasopressin (at replacement doses) should be used to offset the potential drop in SVR from dobutamine, particularly in septic patients where vasopressin deficiency is common 1
• Milrinone and epinephrine also have neutral or beneficial effects on PVR but carry higher hypotension risk 1, 3
• No single agent is absolutely contraindicated, but each must be selected based on its effects on both SVR and PVR 1

Pulmonary Vasodilator Therapy

Inhaled Nitric Oxide - First-Line Pulmonary Vasodilator

Inhaled nitric oxide acutely decreases PVR and improves cardiac output with the critical advantage of having no detrimental effect on systemic vascular resistance 1

• Short half-life and rapid onset of action make it ideal for acute management 1
• Improves oxygenation by enhancing ventilation-perfusion matching 1
• Can cause methemoglobinemia at sustained high doses 1
• Critical warning: Rebound pulmonary hypertension can occur upon weaning, so discontinuation must be gradual 1

PAH-Specific Targeted Therapies

The 2024 International Consensus guidelines identify three therapeutic pathways 1:

Nitric oxide-cGMP pathway enhancers:

• Phosphodiesterase-5 inhibitors: sildenafil, tadalafil, riociguat 1

Prostacyclin pathway agonists:

• Epoprostenol or treprostinil 1
• Epoprostenol is initiated at 2 ng/kg/min and increased in 2 ng/kg/min increments every 15 minutes until dose-limiting effects occur 4

Endothelin pathway antagonists:

• Bosentan or ambrisentan 1

Restart Home Medications Immediately

• If the patient was on chronic pulmonary vasodilator therapy that was discontinued, restarting these medications is crucial and takes priority 5
• Patients may rapidly develop right ventricular failure and death without their maintenance therapies 2

Sedation and Analgesia Strategy

• Use opioids, sedatives, and neuromuscular blocking agents to reduce sympathetic surge and oxygen consumption 1
• These agents help prevent further increases in pulmonary vascular resistance from pain and agitation 1

Volume Management - The Delicate Balance

• Patients with right ventricular failure are often volume overloaded, but aggressive diuresis can precipitate cardiovascular collapse 2
• Careful volume management is imperative, especially in hypotension 2
• In shock, vasopressors and inotropes rather than fluid boluses are required to augment cardiac output and reduce right ventricular ischemia risk 2
• The right ventricle is preload-dependent but easily overdistended, making volume resuscitation a double-edged sword 3, 6

ECMO Consideration - Know When to Escalate

ECMO should be considered before cardiac arrest occurs in patients who develop signs of pulmonary hypertensive crisis, low cardiac output, or right ventricular failure despite optimal medical therapy 1

• ECMO can serve as a bridge to recovery or bridge to transplant evaluation in select cases 1
• For refractory cardiac arrest (ECPR), ECMO may be lifesaving 1
• Early consultation with a pulmonary hypertension specialist and transfer to a tertiary center with ECMO capabilities is advised 2

Common Pitfalls to Avoid

What NOT to Do

• Never give large fluid boluses in hypotensive PH patients - this worsens right ventricular distension and ischemia 2, 6
• Avoid excessive blood pressure reductions that can lead to coronary, cerebral, or renal ischemia (Note: This is from general hypertensive emergency guidelines 7, 8 and does not apply to PH crisis management)
• Do not delay restarting home pulmonary vasodilators 5
• Avoid hypoxia, hypercarbia, and acidosis at all costs 1

Mortality Context

• The risk of death for children with pulmonary hypertension admitted to ICU is 10% versus 3.9% for other cardiac admissions 1
• 6.1% of PH admissions experience a cardiopulmonary resuscitation event 1
• Patients with PH and in-hospital cardiac arrest have lower survival to discharge (59.1% vs 61.6%) 1
• However, a more recent multicenter study found that pre-arrest pulmonary hypertension was not associated with statistically significant differences in survival when modern management strategies were employed 1

Disposition and Monitoring

• All patients with pulmonary hypertension crisis require ICU admission with continuous hemodynamic monitoring 1, 6
• Ideally, transfer to a center with pulmonary hypertension expertise, invasive monitoring capabilities, and mechanical support options (right ventricular assist device, ECMO) 2, 6
• These patients should not be managed in general emergency departments without specialist consultation 2