MCC ICU Topic Deep Dive: Pulmonary Hypertension 

Definition: Elevated blood pressure within the pulmonary arteries. There are def

ined parameters for pulmonary vascular resistance and wedge pressures, but for the purposes of this teaching segment we will focus on measured PA pressures only and assume that your patient has pre-diagnosed pulmonary hypertension. There are also pre capillary, post capillary, and combined versions of pulmonary hypertension. Again, to keep this simplified, we will focus on just PA pressures for this segment. 

Grade 1 (Mild): SBP 30 - 50 or DBP 20 - 25,  MAP > 20 

Grade II (Moderate): SBP 50 - 70 or DBP 26 - 35, MAP > 40

Grade III (Severe): SBP 70 - 110 or DBP 36 - 45, MAP >50

Grade IV (Systemic): SBP > 110 or DBP > 45, MAP > 60 

Pulmonary hypertension is further delineated by the etiology of the elevated pressure. 

WHO Group I: Pulmonary Arterial Hypertension. The source of elevated pressure is narrowed, stiff, or thickened pulmonary arteries. This is idiopathic or can be associated with connective tissues disorders, drug exposure, or congenital heart disease 

WHO Group II: Left Heart Failure Mediated. The source of elevated pressure is LV failure, cardiomyopathy, or valve disease of the left side of the heart.

WHO Group III: Pulmonary disease mediated. Reduced lung function and hypoxia from COPD, ILD, or sleep apnea results in poor circulation through the lungs and results in elevated pulmonary pressures. 

WHO Group IV: Chronic Thromboembolism. Chronic pulmonary embolism results in restricted flow through the pulmonary vasculature resulting in elevated blood pressures. 

WHO Group V: Unclear or multifactorial. In this category the elevated blood pressure has a source that is poorly understood or due to multiple issues. Examples include sarcoidosis, sickle cell, lupus, and several hematological and metabolic disorders. 

After severity and group is determined, that patient is placed in a functional class of pulmonary hypertension. 

Functional Class 1: No symptoms, even with activity 

Functional Class 2: No symptoms at rest, but slight discomfort or shortness of breath and limits with normal activities. 

Functional Class 3: Symptom free at rest, but any activity is limited by shortness of breath and/or fatigue. 

Functional Class 4: Symptoms at rest and severe symptoms with any activity. 

Symptoms: Shortness of breath (dyspnea), Fatigue, Chest pain or pressure, Dizziness or fainting (syncope), Swelling in the legs, ankles, or abdomen, JVD, Rapid heartbeat, transaminitis (Hepatic congestion) 

Diagnosis: Right heart catheterization (gold standard), echocardiogram. There may be evidence of PH on EKG, CTA, or PFT’s as well. 

                                                   Pharmacologic Treatment: 

Calcium Channel Blockers: Result in blood vessel dilation. A very small percentage of patients in group I PH only will be CCB responsive. This should be tested during the initial right heart 

catheterization and is generally not implemented at the bedside without evidence. 

Diuretics (Water Pills) – Reduce fluid buildup and edema with potential benefit in all WHO groups of pulmonary hypertension. 

Anticoagulation (Warfarin, Apixaban, Xarelto, Pradaxa): : Impedes thrombus formation. These are for group 4 pulmonary hypertension (CTEPH). There is limited evidence to suggest that anticoagulation may be beneficial in group 1 pulmonary hypertension as well, although this has not been consistent in studies. As of 2025, anticoagulation for group 1 is not standard of practice.

Phosphodiesterase-5 Inhibitors (e.g., Sildenafil, Tadalafil): Result in blood vessel vasodilation and lower pressure. These are for group 1 pulmonary hypertension only. 

Pulmonary Vasodilators (e.g., Epoprostenol, Treprostinil, Iloprost):  Result in blood vessel vasodilation. These are for group 1 pulmonary hypertension only. 

Endothelin Receptor Antagonists (e.g., Bosentan, Ambrisentan, Macitentan):  Blocks endothelin receptors which narrow blood vessels when stimulated. These are for group 1 pulmonary hypertension only. 

Soluble Guanylate Cyclase Stimulators (e.g., Riociguat):  Improves blood vessel relaxation by promoting nitric oxide production. Riociguat is FDA approved for WHO group I and group IV pulmonary hypertension. 

Oxygen Therapy – Oxygen by itself acts as a pulmonary vasodilator and a goal of O2 saturation above 92% is reasonable. 

                                    Nonpharmacologic Treatment

Regular exercise

Low-sodium diet to reduce fluid retention

Avoiding smoking and alcohol

Managing stress and maintaining a healthy weight

Balloon Atrial Septostomy 

Pulmonary Thromboendarterectomy (PTE) 

Lung Transplant or Heart-Lung Transplant 

       Treatment path usually follows an algorithm noted on the top right side of this page. 

Random Dan Advice: 

• As you can tell from the above, the vast majority of medication available targets WHO I pulmonary hypertension. You need to know the cause of your patient’s PH and treat appropriately. Treat heart failure, clots, or lung disease as you normally would if it is the source of your patient’s high PA pressures. 
• For your patient’s with WHO I pulmonary hypertension, their ability to have medications covered by insurance depends on their functional class. Starting tadalafil or asking for an IV vasodilator will depend on how symptomatic they are on a day to day basis. These medications typically are not started in an ICU setting unless pulmonary hypertension group I (or IV in the case of Riociguat)  has been confirmed and is believed to be the etiology of the patient’s symptoms. 
• Pulmonary hypertension treatment is highly specialized and medication choice should be the decision of a pulmonologist that specializes and can follow up with PH patients. It would be rare that initial PH treatment would be started by an ICU team without assistance. 
• In an emergency,  and especially if the cause of the PH is unknown, flolan or inhaled nitric oxide are of consideration to test at the bedside with great caution. For a patient that has heart failure induced PH, there is evidence of harm with many of the medications typically trialed for advanced group 1 PH (See FIRST trial and MELODY below). A couple points about this. One, you must have a way to measure if these treatments are working (Swan Ganz). And two, keep your expectations low and don't hesitate to stop treatment if there is no effect. Only a small subset of group I PH will respond and for the vast majority of PH patients there will be no benefit (and only 5-10% of group I will respond in the short term with only half of the responding patients showing continued response in the long term). 

Recent evidence for/against some of the above. 

European Respiratory Review 2023 32(167): 220211; DOI: https://doi.org/10.1183/16000617.0211-2022