DESCRIPTION

Inability to breathe comfortably

• Describes a symptom of many possible underlying diseases
• Is different from signs of increased work of breathing
• Usually an unconscious activity, dyspnea is the subjective sensation of breathing, from mild discomfort to feelings of suffocation.
• Dyspnea comes from the Greek word for "hard breathing."
• Often described as "shortness of breath"
• Common presenting complaint seen in 3.5% of ED visits
• Caused by difficulties in maintaining homeostasis with respect to gas exchange and acid–base status
• Dyspnea usually reflects an impairment in ventilation, perfusion, metabolic function, or CNS drive.
• Mechanisms that control breathing:
  • Control centers:
    • Brainstem and cerebral cortex affect both automatic and voluntary control of breathing.
  • Chemo, stretch, and irritant sensors:
    • CO₂ receptors located centrally and PO₂ receptors located peripherally.
    • Mechanoreceptors lie in respiratory muscles and respond to stretch.
    • Intrapulmonary mechanoreceptors respond to chemical irritation, engorgement, and stretch.
  • Effectors of respiratory center output are in the respiratory muscles and respond to central stimulation to move air in and out of the thoracic cavity.
  • Motor–sensory control of the diaphragm and muscles of respiration are controlled by C3–C8 nerves and T1–T12 nerves.
• Derangements of any of these neurosensory pathways produces dyspnea:
  • Many etiologies for the sensation of dyspnea are due to the complex nature of mechanisms that control breathing.

ETIOLOGY

• Upper airway:
  • Epiglottitis
  • Laryngeal obstruction
  • Tracheitis or tracheobronchitis
  • Angioedema
• Pulmonary:
  • Airway mass
  • Asthma
  • Bronchitis
  • Chest wall trauma
  • CHF
  • Drug-induced conditions (e.g., crack lung, aspirin overdose)
  • Effusion
  • Emphysema
  • Lung cancer
  • Metastatic disease
  • Pneumonia
  • Pneumothorax
  • Pulmonary embolism
  • Pulmonary HTN
  • Restrictive lung disease
• Cardiovascular:
  • Arrhythmia
  • Coronary artery disease
  • Intracardiac shunt
  • Left ventricular failure
  • Myxoma
  • Pericardial disease
  • Valvular disease
• Neuromuscular:
  • CNS disorders
  • Myopathy and neuropathy
  • Phrenic nerve and diaphragmatic disorders
  • Spinal cord disorders
  • Systemic neuromuscular disorders
• Metabolic acidosis:
  • Sepsis
  • DKA
  • AKA
  • Renal failure
  • Profound thiamine deficiency
• Toxic:
  • Methemoglobinemia
  • Salicylate poisoning
  • Cellular asphyxiants:
    • Carbon monoxide
    • Cyanide
    • Hydrogen sulfide
    • Sodium azide
  • Toxic alcohols
• Abdominal compression:
  • Ascites
  • Pregnancy
  • Massive obesity
• Psychogenic:
  • Hyperventilation
  • Anxiety
• Other:
  • Altitude
  • Anaphylaxis
  • Anemia

Geriatric Considerations

• Most common diagnoses in elderly patients presenting to the ED with dyspnea:
  • Decompensated heart failure
  • Pneumonia
  • COPD
  • Pulmonary embolism
  • Asthma

Pediatric Considerations

• Common conditions in differential diagnosis for age < 2 yr:
  • Asthma
  • Croup
  • Congenital anomalies of the airway
  • Congenital heart disease
  • Foreign-body aspiration
  • Nasopharyngeal obstruction
  • Shock

[Outline]

• DESCRIPTION
• ETIOLOGY

SIGNS AND SYMPTOMS

• Difficult, labored, or uncomfortable breathing
• Upper airway:
  • Stridor
  • Upper-airway obstruction
• Pulmonary:
  • Tachypnea
  • Accessory muscle use
  • Wheezing
  • Rales
  • Asymmetric breath sounds
  • Poor air movement
  • Prolonged expiratory phase
• Cardiovascular:
  • S3 gallop
  • Murmur
  • Jugular venous distention
• CNS:
  • Altered levels of consciousness
• General:
  • Diaphoretic/cool vs. hot/dry skin
  • Pallor
  • Upright patient position
  • Clubbing
  • Cyanosis
  • Edema
  • Ketotic breath odor

History

• Previous history of dyspnea
• Time course, abruptness of onset, triggers, and severity
• History of stridor or wheezing
• Exercise (activity) tolerance
• Medications and recent compliance
• Exposure to allergens
• Past medical history
• Associated symptoms:
  • Chest pain
  • Fever
  • Cough
  • Hemoptysis

Physical Exam

• Signs of acute distress:
  • Altered mental status
  • Cyanosis
  • Respiratory rate
  • Retractions suggest severe disease
• Listen for abnormal lung sounds:
  • Stridor
  • Rales
  • Wheezing
  • Decreased breath sounds

ESSENTIAL WORKUP

• Pulse oximetry:
  • May be falsely elevated due to increased ventilation or carbon monoxide
• End tidal CO₂:
  • Quickly gives hint of PaCO₂
  • Waveform can give clue to etiology
• CXR:
  • For diagnosis of pulmonary conditions
  • Assess heart size and evidence of CHF
• ABG:
  • Oxygenation
  • Calculate arterial–alveolar gradient:
    • A–a (at sea level) = 150 – (PO₂ – PCO₂)/0.8, normal 5–20
  • Assess degree of acidosis

DIAGNOSIS TESTS & INTERPRETATION

Lab

• CBC:
  • Evaluation for anemia
  • Neutrophil count helpful in evaluation of infectious processes
• Electrolyte, BUN, creatinine, glucose:
  • Consider when specific metabolic derangements are suspected
  • B-type natriuretic peptide may be elevated in CHF
• Toxicology screen
• Methemoglobin/carboxyhemoglobin level
• Thyroid function tests
• D-dimer (ELISA):
  • Useful for excluding pulmonary embolus if normal

Imaging

• Chest x-ray for infiltrate, effusion, pneumothorax, or vascular consolidation
• Ventilation–perfusion scan or CT pulmonary angiogram for suspected pulmonary embolism
• Soft tissue neck radiograph or fiberoptic visualization for suspected upper airway obstruction

Diagnostic Procedures/Surgery

• EKG for suspected myocardial ischemia, CHF, suspected pericardial effusion/tamponade
• Peak expiratory flow/spirometry to assess for reactive-airway disease
• Tensilon test for suspected myasthenia gravis

DIFFERENTIAL DIAGNOSIS

• Anticholinergic or adrenergic toxidrome
• Thyroid storm
• Munchausen syndrome

[Outline]

• SIGNS AND SYMPTOMS
• ESSENTIAL WORKUP
• DIAGNOSIS TESTS & INTERPRETATION
• DIFFERENTIAL DIAGNOSIS

PRE-HOSPITAL

• Place all patients on supplemental oxygen, pulse oximetry, end tidal CO₂, and cardiac monitor.
• Initiate therapy for suspected cause of dyspnea when indicated:
  • Asthma
  • COPD
  • CHF
• Utilize advanced airways in the face of impending respiratory failure.

INITIAL STABILIZATION/THERAPY

• ABCs
• Immediate intubation for impending respiratory arrest:
  • Altered mental status
  • Unstable vital signs
• BiPAP in alert patients:
  • Contraindications:
    • Cardiac instability
    • Suspicion of upper airway obstruction
    • Inability to protect airway
    • Upper GI bleeding
    • Status epilepticus

ED TREATMENT/PROCEDURES

• Based on underlying etiology
  • Antibiotics and fluid for pneumonia
  • CPAP and diuretics for CHF
  • Bronchodilators and steroids for asthma
  • Aspirin, heparin, and lyrics/cath lab for MI
  • Other treatments as necessary for other etiologies
• Palliative care with opiates is indicated for the relief of dyspnea in terminally ill patients.

[Outline]

• PRE-HOSPITAL
• INITIAL STABILIZATION/THERAPY
• ED TREATMENT/PROCEDURES

DISPOSITION

Admission Criteria

• Assisted ventilation
• Hypoxia
• A–a gradient > 40
• Medical condition requiring hospital therapy

Discharge Criteria

• Adequate oxygenation
• Stable medical illness that can be managed as outpatient
• Adequate ambulatory pulse ox

Issues for Referral

Based on suspected underlying etiology

FOLLOW-UP RECOMMENDATIONS

• Patients should be told not to smoke while short of breath and to try to quit to help with some of the causes, as well as to prevent others from getting worse.
• The patient should return for any of the following problems:
  • No improvement or worsening in 24 hr
  • New chest pain, pressure, squeezing, or tightness
  • Shaking chills, or a fever > 102°F
  • New or worsening cough or wheezing
  • Abdominal (belly) pain, vomiting, severe headache
  • Dizziness, confusion, or change in behavior
  • Any serious change in symptoms, or any new symptoms that are of concern

[Outline]

• DISPOSITION
• FOLLOW-UP RECOMMENDATIONS

• Altered mental status is an indication for immediate airway management in a patient with severe dyspnea.
• Dyspnea can and should be quantified.
• Dyspnea and tachypnea may occur without a respiratory etiology because of metabolic derangement or a catastrophic CNS event.

ICD9

• 786.05 Shortness of breath
• 786.07 Wheezing
• 786.09 Other respiratory abnormalities

ICD10

• R06.00 Dyspnea, unspecified
• R06.02 Shortness of breath
• R06.2 Wheezing

[Outline]

• ICD9
• ICD10

• Camargo CA Jr, Rachelefsky G, Schatz M. Managing asthma exacerbations in the emergency department: Summary of the National Asthma Education and Prevention Expert Panel Report 3 guidelines for the management of asthma exacerbations. J Allergy Clin Immunol. 2009;124(2 suppl):S5–S14.
• De Peuter S, Van Diest I, Lemaigre V, et al. Dyspnea: The role of psychological processes. Clin Psychol Rev. 2004;24(5):557–581.
• Mahler DA, Selecky PA, Harrod CG, et al. American College of Chest Physicians consensus statement on the management of dyspnea in patients with advanced lung or heart disease. Chest. 2010;137(3):674–691.
• Stenton C. The MRC breathlessness scale. Occup Med (Lond). 2008;58:226–227.
• Weintraub NL, Collins SP, Pang PS, et al., Acute heart failure syndromes: Emergency department presentation, treatment, and disposition: Current approaches and future aims: A scientific statement from the American Heart Association. Circulation. 2010;122:1975–1996.

See Also (Topic, Algorithm, Electronic Media Element)

Respiratory Distress

Matthew M. Hall