What is the management approach for desaturations in patients?

Management of Inpatient Desaturations

For any patient with SpO2 <85%, immediately initiate high-flow oxygen at 15 L/min via reservoir mask regardless of underlying conditions (including COPD or hypercapnic risk), while simultaneously performing rapid assessment to identify the underlying cause. 1

Initial Oxygen Delivery Strategy

Severity-Based Approach:

• Critical desaturation (SpO2 <85%): Administer the highest possible inspired oxygen concentration using a reservoir mask at 15 L/min immediately, without delay for any reason including concerns about hypercapnia 1

• Moderate desaturation (SpO2 85-93%): Start oxygen at 2-6 L/min via nasal cannulae or 5-10 L/min via simple face mask 1

• Target saturations: Aim for SpO2 94-98% in most acutely ill patients 1. However, for patients with COPD, morbid obesity, cystic fibrosis, chest wall deformities, neuromuscular disorders, or bronchiectasis with fixed airflow obstruction, target SpO2 88-92% instead 1

Immediate Clinical Assessment Algorithm

Perform rapid ABCDE assessment to identify life-threatening causes: 2

• Airway: Check for obstruction, verify pulse oximetry signal quality and proper probe placement, ensure waveform correlates with pulse rate 1, 2

• Breathing: Assess for tension pneumothorax, massive pulmonary embolism, acute pulmonary edema, endobronchial intubation (causes nearly 20% of all desaturations under anesthesia) 1, 3

• Circulation: Record heart rate and rhythm, blood pressure, assess for low cardiac output states 1, 2

• Disability: Evaluate mental status and level of consciousness 1, 2

• Exposure: Check temperature and other contributing factors 2

Management for Patients Requiring Intubation

Preoxygenation Protocol:

• Use tight-fitting facemask with circuit capable of delivering CPAP (5-10 cm H2O) if oxygenation is impaired 1

• For severe hypoxemia (PaO2/FiO2 <200): Non-invasive positive pressure ventilation (NIPPV) has the strongest evidence for decreasing critical desaturation during rapid sequence intubation, with desaturation rates of 24% compared to 35% with high-flow nasal oxygen (HFNO) 4

• Apply nasal oxygen at 5 L/min during preoxygenation while awake, then increase to 15 L/min when consciousness is lost 1

• Continue nasal oxygen at 15 L/min or HFNO at 30-70 L/min during laryngoscopy to provide apneic oxygenation 1

For agitated/uncooperative patients: Use medication-assisted preoxygenation (delayed sequence intubation) with sedative-hypnotic agents to facilitate tolerance of preoxygenation devices before administering neuromuscular blocking agents 4

Monitoring and Titration

Continuous monitoring requirements: 5

• Monitor oxygen saturation continuously in critically ill patients or at minimum every 4 hours in stable patients 5

• Observe for at least 5 minutes after initiating or adjusting oxygen therapy 5

• Record oxygen delivery device and flow rate on monitoring charts 1, 5

• Monitor for signs of inadequate oxygen delivery: tachycardia, hypotension, altered mental status 2

Oxygen Weaning Protocol

Step-down approach: 1, 5

• Lower oxygen concentration when patient is clinically stable and oxygen saturation is above target range for 4-8 hours 5

• Never abruptly discontinue oxygen as this causes life-threatening rebound hypoxemia with rapid fall below baseline SpO2 1, 5

• Step down oxygen to the lowest level required to maintain SpO2 88-92% (or 94-98% in non-hypercapnic patients) 1

• Discontinue oxygen once patient maintains saturation within or above target range on room air, but leave prescription in place for potential deterioration 1, 5

Special Population Considerations

Acute coronary syndrome patients: Do not routinely administer oxygen if SpO2 ≥94%, as supplemental oxygen in normoxemic ACS patients increases myocardial injury, infarction size, reinfarction rates, and cardiac arrhythmias 1

Neuromuscular disease/chest wall disorders: Rapid desaturation during breaks from NIV and difficulty achieving adequate oxygenation are important warning signs suggesting need for HDU/ICU placement 4

Obese patients: Position in ramped position (head-up 35°) to improve functional residual capacity and reduce rapid desaturation risk 2

Pregnant patients: Target SpO2 94-98% and position in full left lateral position or use left lateral tilt to avoid aortocaval compression 1

Critical Pitfalls to Avoid

• Pulse oximetry may be inaccurate below 80% saturation 2

• Supplemental oxygen may mask hypoventilation by delaying onset of hypoxemia 2

• Do not rely on clinical signs alone (such as cyanosis) to detect hypoxemia, particularly in patients with dark complexion 5

• In persistent desaturation without apparent cause, management should include hand ventilation with 100% oxygen, and consider blood gases, chest radiography, and bronchoscopy 3

• Half of persistent desaturations are due to pulmonary problems (underlying lung disease, excessive secretions, obesity) and one-third cannot be diagnosed initially 3