6 Respiratory Emergencies and Complications

Recognize and respond

Acute respiratory emergencies can rapidly impair airway patency, oxygenation, ventilation, or all three. Early recognition and support are critical while the underlying cause is treated. The guidance here concerns initial adult care; pediatric care and medication choices require age-appropriate protocols.

Assess the patient

Assess the patient promptly. Determine whether the airway is open, breathing is effective, and the patient is alert, speaking, and moving air. Look for stridor, wheezing, unusually quiet breath sounds, accessory-muscle use, cyanosis, poor air movement, exhaustion, or altered mental status. Falling respiratory effort in a patient who remains severely ill can indicate fatigue rather than recovery.

Activate emergency or advanced clinical support for severe distress, suspected airway obstruction, worsening oxygenation, or declining consciousness. When appropriate, position the patient to ease breathing; open and clear the airway, suction visible secretions, and use airway adjuncts or assisted ventilation within your training and local protocol. Apply pulse oximetry, provide oxygen for hypoxemia, and frequently reassess breathing, mental status, and response to treatment. Obtain ECG, blood gas, imaging, or other tests as indicated, without delaying stabilization.

Support oxygenation and ventilation

Oxygenation is the transfer of oxygen into the blood; ventilation is the movement of air that removes carbon dioxide. Supplemental oxygen may improve hypoxemia, but it does not correct inadequate ventilation. Titrate oxygen to the patient and local protocol. One adult acute-care guideline suggests an $SpO_2$ target of $94\text{–}98\%$ for most acutely ill adults and $88\text{–}92\%$ for patients with COPD or risk of carbon-dioxide retention. Do not treat a saturation number in isolation; assess the whole patient.

If breathing is absent or inadequate, support ventilation with a bag-mask device and supplemental oxygen when available. Aim for visible chest rise and avoid rapid or forceful breaths. For an adult with a pulse who is not breathing normally, AHA guidance considers one breath every $6$ seconds reasonable. Escalate to a more advanced airway when basic support cannot maintain airway patency, oxygenation, or ventilation, or when deterioration makes airway loss imminent. Advanced airway placement requires trained clinicians and continued reassessment.

Waveform capnography displays exhaled carbon dioxide over time and can help assess ventilation and trends. Continuous waveform capnography is recommended to confirm and monitor endotracheal-tube placement during resuscitation. A sudden change or loss of the waveform warrants immediate assessment of the patient, airway, breathing circuit, and circulation. End-tidal $CO_2$ is not the same as arterial $CO_2$; the values may diverge, particularly with severe lung disease or poor perfusion.

Airway obstruction

Upper-airway obstruction may cause noisy breathing or stridor, difficulty speaking, a weak or absent cough, and eventually silence or loss of consciousness. Causes include foreign bodies, swelling, secretions, and reduced consciousness. Open and clear the airway and summon help.

For a conscious adult with severe foreign-body airway obstruction, the 2025 AHA algorithm recommends repeated cycles of five back blows followed by five abdominal thrusts. Use chest thrusts when abdominal thrusts are not suitable. If the person becomes unresponsive, begin CPR and look for a visible object before giving breaths; do not perform blind finger sweeps. Suspected swelling or rapidly worsening obstruction needs urgent advanced airway support.

Bronchospasm

Asthma or COPD exacerbation commonly causes wheezing, prolonged exhalation, cough, and increased work of breathing. Severe bronchospasm may produce very poor air movement or a “silent chest.” Worsening fatigue, confusion, or reduced responsiveness are danger signs.

Give inhaled short-acting bronchodilator treatment according to protocol; ipratropium and systemic corticosteroids are commonly added for significant exacerbations. Provide oxygen for hypoxemia and escalate urgently if the patient worsens or does not respond. In a patient with severe asthma, a normalizing or rising $CO_2$ can be concerning for fatigue and ventilatory failure; interpret it in clinical context.

Pulmonary edema

Acute pulmonary edema often presents with severe breathlessness, low oxygen saturation, crackles, and sometimes pink, frothy sputum. Orthopnea, raised neck veins, or leg swelling may suggest a cardiac cause, but other causes are possible.

Sit the patient upright if tolerated, support oxygenation, and obtain urgent emergency evaluation. CPAP or other noninvasive positive-pressure ventilation may help selected patients who are alert and able to protect their airway. Monitor closely, and do not let this support delay escalation if the patient deteriorates. Treat the underlying cause under clinical direction; vasodilators or diuretics may be appropriate in selected cases, not automatically for every patient with crackles.

Respiratory failure

Respiratory failure occurs when the respiratory system cannot maintain adequate oxygenation, ventilation, or both. Suspect it with persistent hypoxemia, inadequate or tiring breathing, rising $CO_2$ with acidemia, inability to protect the airway, or altered mental status. Pulse oximetry estimates oxygenation but does not measure ventilation; blood gases and clinical assessment may be needed.

Provide oxygen for hypoxemia, correct reversible causes, and support ventilation when breathing is inadequate. Noninvasive ventilation may be appropriate for selected patients. Worsening mental status, inability to protect the airway, hemodynamic instability, or failure to improve calls for immediate escalation and consideration of invasive airway management.

Reassess and escalate

Recognize distress early, call for help, maintain the airway, support oxygenation and ventilation, and reassess continuously. Treat the likely cause while preparing to escalate if the patient fatigues, becomes confused, or fails to improve. Use pulse oximetry and capnography as monitoring tools, not substitutes for clinical assessment.