Summary
Definition
History and exam
Key diagnostic factors
- direct trauma to the thorax and neck
- dyspnea
- confusion
- tachypnea
- accessory breathing muscle use
- stridor
- inability to speak
- retraction of intercostal spaces
- cyanosis
- loss of airway/gag reflex
Other diagnostic factors
- anxiety
- headache
- hypoventilation
- cardiac rhythm disturbances
- underlying neuromuscular disorder
- drug use
- seizure
- coma
- asterixis
- papilledema
Risk factors
- cigarette smoking
- young age
- older age
- pulmonary infection
- chronic lung disease
- upper airway obstruction
- lower airway obstruction
- alveolar abnormalities
- perfusion abnormalities
- cardiac failure
- peripheral nerve abnormalities
- muscle system abnormalities
- opioid and sedative medications
- toxic fumes and gases
- traumatic spinal injury
- traumatic thoracic injury
- central nervous system (CNS) disorders
- acute vascular occlusion
- pulmonary effusion
- pneumothorax
- hypercoagulable states
Diagnostic tests
1st tests to order
- pulse oximetry
- arterial blood gases
Tests to consider
- CBC
- D-dimer
- serum bicarbonate (HCO₃)
- Cardiac troponin I and/or T
- ECG
- chest x-ray
- pulmonary function tests
- Urine or serum toxicology
- chest CT
- CT pulmonary angiography (CTPA)
- ventilation/perfusion lung scan
- capnometry
- cardiothoracic ultrasound
Emerging tests
- transcutaneous CO₂ monitoring
Treatment algorithm
airway obstruction
no acute upper airway obstruction: stable
no acute upper airway obstruction: unstable
Contributors
Authors
Samuel J. Stratton, MD, MPH
Professor
Fielding School of Public Health
David Geffen School of Medicine at UCLA
Los Angeles
Deputy Health Officer
Orange County Health Care Agency
Health Disaster Management/Emergency Medical Services
Santa Ana
CA
Disclosures
SJS declares that he has no competing interests.
Peer reviewers
C. Michael Roberts, MA, MD, FRCP
Consultant Physician
Barts Health
London
UK
Disclosures
CMR declares that he has no competing interests.
Ken Miller, MD, PhD
University of California
Irvine and Orange County Fire Authority
Irvine
CA
Disclosures
KM declares that he has no competing interests.
Christopher Kahn, MD, MPH
Assistant Professor of Clinical Emergency Medicine
Department of Emergency Medicine
University of California
Irvine and Orange County Fire Authority
Irvine
CA
Disclosures
CK declares that he has no competing interests.
Differentials
- Hyperventilation secondary to metabolic acidosis
- Hyperventilation secondary to anxiety
- Sleep apnea
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