3 Acute Respiratory Failure
Learn how acute respiratory failure is classified, recognized, assessed, and managed, including ABG interpretation and priorities for ventilatory support.
Classification and core concepts
occurs when the lungs cannot adequately oxygenate blood, remove carbon dioxide, or both. It is commonly classified as hypoxemic, meaning oxygenation failure, or hypercapnic, meaning ventilatory failure.
Causes and clinical patterns
involves impaired oxygenation. Findings such as can support the diagnosis, but they must be interpreted in context, including the patient’s baseline and clinical condition.
Causes of hypoxemia include pneumonia, pulmonary edema, atelectasis, pulmonary embolism, and acute respiratory distress syndrome (ARDS). Pneumonia can fill or inflame alveoli, impair oxygen transfer, and lead to hypoxemia. Diffuse lung opacities with a of despite supplemental oxygen are an example of findings consistent with this type of failure.
results from inadequate alveolar ventilation. A with acidemia can support the diagnosis, with interpretation guided by the patient’s baseline and clinical condition. Causes can include COPD exacerbation, sedative or opioid effects, neuromuscular weakness, and respiratory muscle fatigue.
Recognizing deterioration
Signs that may signal worsening hypoxemia or ventilatory fatigue include restlessness, confusion, tachypnea, diaphoresis, and accessory-muscle use. A patient whose shortness of breath worsens and who develops these findings requires prompt reassessment rather than waiting for the next scheduled vital-sign check.
Assess airway, breathing, oxygen saturation, work of breathing, and mental status. Provide prescribed oxygen, summon appropriate clinical support, and prepare to escalate care if the patient is deteriorating.
Assessment and ABG interpretation
Pulse oximetry helps detect hypoxemia. An can assess oxygenation, ventilation, and acid–base status, while chest imaging can help identify causes such as pneumonia or pulmonary edema. Select tests according to the clinical presentation; do not delay needed oxygen support while awaiting results.
In an ABG with , , and , the low pH indicates acidemia and the elevated indicates a primary respiratory cause. The near-normal bicarbonate is consistent with limited renal compensation, as may occur in an acute process. Interpret results alongside the clinical status and prior results; a chronically elevated may represent a different baseline.
Oxygen and ventilatory support
Begin appropriate oxygen or ventilatory support promptly and monitor the response. In a COPD exacerbation with respiratory distress and acute respiratory acidosis, may be appropriate for a patient who is alert and cooperative, if there are no contraindications. NIV can support ventilation and reduce the need for intubation in selected patients, but it requires close monitoring.
Worsening distress, declining consciousness, inability to protect the airway, or failure to improve calls for urgent reassessment and possible invasive ventilation. Administer oxygen and adjust it to the prescribed target; elevated carbon dioxide is not a reason to withhold needed oxygen.
Mechanical ventilation priorities
If a mechanically ventilated patient suddenly becomes hypoxemic and distressed, rapidly assess the patient and airway first. Check oxygen delivery, the airway, tubing and connections, and the ventilator display; summon the respiratory therapist or emergency support while intervening within scope and local protocol.
A may indicate a patient problem or an equipment problem. Do not silence the alarm and leave without assessing the patient, change ventilator settings without assessment or authorization, or disconnect the ventilator and wait for the alarm to stop. Ongoing care includes monitoring trends in oxygenation and ventilation, airway security, patient–ventilator synchrony, and ordered ventilator parameters.