Pulmonary hypertension

Revision as of 00:29, 30 January 2016 by Rossdonaldson1 (talk | contribs) (Diagnosis)

Background

  • Definition: mean PA pressure >25mmHg assessed by right heart catheterization

Types

  • Group 1: Idiopathic pulmonary arterial hypertension, formerly called primary PH
  • Group 2: PH due to left heart disease (systolic/diastolic dysfunction and valvular heart dz)
  • Group 3: PH due to lung diseases or various causes of hypoxemia, such as COPD, ILD, or sleep-disordered breathing
  • Group 4: PH due to chronic thromboembolic disease
  • Group 5: PH of unclear multifactorial mechanisms (myeloproliferative dz, sarcoidosis, glycogen storage dz, etc)

Etiologies

  • heritable
  • idiopathic
  • associated with connective tissue disease, HIV, portal HTN, congenital heart dz, schistosomiasis, chronic hemolytic anemia
  • due to lung disease, left heart disease, chronic exposure to high altitudes, chronic thromboembolic disease, myeloproliferative disorders, sarcoidosis, vasculitis, glycogen storage disease, Gaucher disease, chronic renal failure on dialysis

Clinical Features

History

  • Exertional dyspnea (most common symptom)[1]
  • Consider in undifferentiated patients with dyspnea, fatigue, syncope (late PH finding), chest pain, palpitations, LE edema

Physical exam

  • JVD
  • hepatomegaly
  • ascites
  • edema
  • stigmata of liver failure

Differential Diagnosis

Acute dyspnea

Emergent

Non-Emergent

Diagnosis

Testing

  • ECG findings (similar to acute pulmonary embolism):
    • Right axis deviation
    • Evidence of right heart strain
    • S1Q3T3
    • Right ventricular hypertrophy
      • Large R waves in precordial leads
    • Tachyarrhythmias (aflutter or afib)
  • Radiologic findings:
    • CXR:
      • RA enlargement (obliteration of retrosternal space on lateral CXR)
      • Prominent pulmonary vasculature (congestion)
      • PA dilation
    • CT Chest:
      • Pulmonary artery > ascending aorta suggests PH
      • Pulmonary artery diameter greater than 30 mm suggest PH
      • Right heart enlargement
    • Echocardiogram:
      • RVH, RV dilatation and hypokinesis
      • RV close to LV size (+/- septal flattening/bowing)
      • Tricuspid valve regurgitation
    • Estimate systolic pulmonary artery pressure (SPAP) with echo[2]
      • SPAP = Max TR gradient + Mean RAP
      • Cannot use this method with vent-dependent pts, pulmonic stenosis
      • Max TR gradient as measured by tricuspid regurg (TR) jet, which >90% of adults have
        • Use parallel CW Doppler line across TR jet in apical view
        • Obtain dense TR profile below the line with well-defined envelope and measure peak = Max TR gradient
      • Estimate right atrial pressure (RAP) with IVC diameter from subcostal view
Normal Intermediate High
Mean RAP, mmHg 3 8 15
IVC diameter max 2.1 max 2.1 > 2.1
Resp variation >50% <50% <50%

Evaluation

  • Initial diagnosis not typically made in the ED because right-sided heart catheterization needed for definitive diagnosis

Acute Management

PH patients do not tolerate rapid changes in hemodynamics well, all therapies should be instituted with caution.

Optimize Circulation

  1. Optimize (usually reduce) RV preload:
    • Usually euvolemic or hypervolemic, rarely need IVF
    • Diuretics to treat RV failure:
      • Furosemide 20-40mg IV
      • Furosemide drip @ 5-20mg/hr
    • If suspect sepsis or hypovolemia, small (250-500cc) NS challenge to assess fluid responsiveness. If not responsive to IVF challenge, start norepinephrine (MAP > 65 mmHg).
  2. Increase cardiac output:
    • Once MAP >65 mmHg, start low dose dobutamine (5-10mcg/kg/min)
    • Improves inotropic support and theoretically decreases pulmonary vascular resistance
  3. Reduce RV afterload:
    • Avoid hypoxia, maintain O2 sat >90% (increases pulmonary vasoconstriction)
    • Avoid hypercapnea (increases pulmonary vascular resistance)
    • Avoid acidosis
  4. Treat arrhythmias:
    • SVT most common although may also become bradycardic (aflutter and afib occur equally)
    • Treatment of aflutter is often more successful than afib
    • Do not tolerate negative inotropy, deteriorate to RV failure
Do NOT rate control tachycardias, best to electrically cardiovert or attempt rhythm control with amiodarone
  • May require radiofrequency ablation
  • AVOID calcium channel blockers or beta blockers

Optimize Oxygenation

  • Intubated patients should be optimized to increased O2 delivery and minimize hypercapnea, maintain low tidal volumes and low PEEP as tolerated

Early Consultation[3]

  • May require interventions not readily available in the ED:
    • Pulmonary arterial cathteter
    • Inhaled pumonay vasodilators
    • Mechanical support with right ventricular assist device or ECMO

Chronic Therapies

Prostacyclins

Mechanisms of action: vasodilatation, inhibit platelet aggregation

  • Epoprostenol, Iloprost, Treprostinil, Beraprost
    • Complications include acute decompensation if stopped abruptly, diarrhea, edema, headache

Phosphodiesterase Type 5 (PDE5) Inhibitors

Mechanism of Action: vasodilation, increases RV contractility

  • Sildenafil
  • Complications include hypotension with administration of nitrates, flushing, epistaxis, headache

Endothelin receptor antagonists

Mechanism of Action: vasodilation via vascular modulation modulation

  • Bosentan, Ambrisentan
    • Complications include liver failure, supratherapeutic INR,
  • Patients also usually taking digoxin, coumadin, diuretics, home O2. RARELY are they on CCB only if responsive during cath. Consider line infections as complication to chronic infusions.

Disposition

  • Low threshold for admission if acute decompensation

See Also

References

  1. Wilcox et al. "Pulmonary Hypertension and Right Ventricular Failure in Emergency Medicine." Annals of EM. Dec 2015. 66(6):619-631
  2. Critical USG. Echocardiographic assessment of pulmonary artery pressure. 2012. http://www.criticalusg.pl/en/echo/tte/tutorials/echocardiographic-assessment-of-pulmonary-artery-pressures
  3. Wilcox et al. "Pulmonary Hypertension and Right Ventricular Failure in Emergency Medicine." Annals of EM. Dec 2015. 66(6):619-631