Recommended Oxygen Saturation Range for Asthma Exacerbation
For this patient with acute asthma exacerbation, the target oxygen saturation should be 94-98% (Option C: 92% or above is the closest correct answer, though the precise range is 94-98%).
Target Saturation for Acute Asthma
The British Thoracic Society guidelines clearly recommend a target oxygen saturation of 94-98% for patients with acute asthma who are not at risk of hypercapnic respiratory failure 1, 2.
This patient presents with classic acute asthma (wheezing, prolonged expiratory phase, tachypnea, hypoxemia at 89%) without any mentioned risk factors for CO2 retention, making the standard 94-98% target appropriate 2.
The lower target range of 88-92% is reserved specifically for patients with COPD or other conditions at risk for hypercapnic respiratory failure, which does not apply to typical asthma patients 1.
Initial Oxygen Delivery Method
Given the initial SpO2 of 89%, start with nasal cannula at 2-6 L/min or simple face mask at 5-10 L/min 1, 2.
If the saturation had been below 85%, a reservoir mask at 15 L/min would be indicated 1, 2.
Nebulized bronchodilators should be driven by oxygen at flow rates >6 L/min to maintain adequate oxygenation during treatment 2.
Monitoring Requirements
Pulse oximetry should be used continuously to guide oxygen therapy and ensure the patient remains within the 94-98% target range 2.
If the initial PaO2 is <8 kPa (60 mm Hg), if initial PaCO2 was normal or raised, or if the patient deteriorates, repeat blood gas measurements within 2 hours 1, 2.
Monitor respiratory rate, heart rate, and mental status at least twice daily, as tachypnea and tachycardia are more sensitive indicators of hypoxemia than visible cyanosis 1.
Critical Pitfall to Avoid
Do not undertarget oxygen saturation in asthma patients—unlike COPD patients who require lower targets (88-92%) to avoid CO2 retention, asthma patients without chronic respiratory failure need the standard 94-98% range 1, 2.
Conversely, avoid excessive oxygen administration that could lead to hyperoxia, which has been associated with adverse outcomes in critically ill patients 3, 4.
Answer Selection
Among the provided options, Option C (92% or above) is the most appropriate choice, as it encompasses the recommended 94-98% range. Options A (90% or above) and B (91-93%) set the target too low, while option D (93-95%) is too narrow and excludes the upper recommended range of 96-98% 1, 2.