Description

• Fluid from pulmonary capillaries leaks into the lung interstitium and alveoli, leading to hypoxia and respiratory distress.
• Fluid accumulation results from cardiogenic causes (e.g., heart failure) that lead to imbalanced hydrostatic and oncotic pressures within the pulmonary capillaries or from noncardiogenic causes (e.g., acute lung injury) that increase alveolar-capillary membrane permeability.

Epidemiology

• Heart failure: Annual incidence increases with age:
  • Patients aged 35–64: 2/1,000
  • Patients >70: 13.6/1,000:
    • Higher rates among blacks (16.3/1,000) than whites (11.9/1,000)
    • Higher rates among men (15.8/1,000) than women (11.7/1,000)
• Acute lung injury (ALI): 86 cases/100,000/yr (~190,000 cases annually in the US)
• Acute respiratory distress syndrome (ARDS): 64 cases/100,000/yr

Prevalence
Heart failure syndromes: 5.8 million US adults

Risk Factors

• Cardiogenic: HTN, ischemic heart disease, valvular disease, left ventricular hypertrophy (LVH)
• Noncardiogenic: Sepsis, severe systemic inflammatory states, aspiration, pneumonia, trauma

Genetics
Multifactorial

General Prevention

Early detection and treatment of risk factors

Pathophysiology

• Cardiogenic causes will increase hydrostatic pressure in the pulmonary capillaries, leading to increased transvascular filtration of a protein-poor fluid into lung interstitium.
• Systolic dysfunction is due to decreased contractility of the left ventricle (LV), leading to decreased cardiac output, which in turn stimulates the renin–angiotensin system and increases fluid retention. Diastolic dysfunction is often due to decreased LV compliance secondary to hypertrophy.
• Noncardiogenic causes will increase permeability of the lung vasculature, leading to accumulation of protein-rich fluid in the lung interstitium and air spaces. Many causes of this vascular permeability are associated with ALI/ARDS.

Etiology

• Cardiogenic (left-sided heart failure):
  • Impaired contractility:
    • Ischemic heart disease
    • Dilated cardiomyopathy
    • Myocarditis
    • Volume overload
    • Alcoholic cardiomyopathy
  • Increased LV afterload:
    • Systemic HTN
    • Aortic stenosis
    • Cocaine abuse
  • Poor diastolic filling:
    • LV hypertrophy
    • Hypertrophic cardiomyopathy
    • Mitral stenosis
    • Atrial fibrillation
  • High cardiac output states:
    • Thyrotoxicosis
    • Systemic arteriovenous fistulas
    • Anemia
  • Noncompliance with medications or diet
• Noncardiogenic:
  • Severe systemic inflammatory states:
    • Sepsis
    • Severe trauma
    • Severe burns
    • Pancreatitis
    • DIC
  • Pneumonia
  • Aspiration or near-drowning
  • Inhalation of smoke or toxic gases
  • Blood product transfusion
  • Preeclampsia
  • Rapid ascent to high altitude (>2,500 m)
  • Drug toxicity (salicylates, opiates)
  • Embolism (thrombus, fat, air, amniotic fluid)
  • Rapid ascent to high altitude
  • Neurogenic (after head trauma/surgery)
  • Re-expansion (after pneumothorax/thoracentesis)

Commonly Associated Conditions

See “Etiology.”