Prescribing oxygen involves targeting specific oxygen saturation levels based on the patient's condition, with the primary aim to treat hypoxaemia, not breathlessness. Here's a breakdown:
Understanding Oxygen Prescription
Oxygen therapy is crucial for patients with low blood oxygen levels (hypoxaemia). The goal is to increase oxygen saturation in the blood to a safe range.
- Indication: Oxygen is prescribed specifically for hypoxaemia, not simply for breathlessness. This distinction is important to ensure proper treatment.
Target Oxygen Saturation Levels
The British Thoracic Society (BTS) guidelines provide specific target ranges:
| Patient Group | Target Oxygen Saturation Range |
|---|---|
| Most patients | 94-98% |
| Patients at risk of type 2 respiratory failure | 88-92% |
- General Target: The standard target range for most patients is between 94% and 98% oxygen saturation.
- Risk of Type 2 Respiratory Failure: For patients with conditions that put them at risk for type 2 respiratory failure (e.g., severe COPD, obesity hypoventilation), the target range is lower, between 88% and 92%. This is because higher levels of oxygen can be dangerous and can make things worse.
Monitoring and Adjustment
It's essential to monitor patients closely after initiating oxygen therapy:
- Clinical Assessment: The BTS recommends a clinical assessment if the oxygen saturation decreases by 3% or more below the patient's target range. For instance, if a patient's target is 94-98% and their saturation falls to 91%, this warrants evaluation.
- Adjusting Flow Rate: Based on monitoring, adjust the oxygen flow rate to maintain the target saturation levels.
Practical Considerations
- Oxygen Delivery Devices: Oxygen can be delivered through various devices including nasal cannulas, face masks, or non-rebreather masks. The choice of device will depend on the patient's needs and the required oxygen flow rate.
- Individual Needs: Always tailor the oxygen prescription to the individual patient, considering their underlying medical conditions and response to therapy.
Example
- A patient admitted with pneumonia is found to have an oxygen saturation of 89%. Their target saturation should be 94-98%. Oxygen should be started via nasal cannula. The saturation should be monitored and the flow of oxygen adjusted to bring the saturation within the appropriate range.
In summary, oxygen prescription requires understanding the indication, setting target saturation levels based on individual risk, monitoring closely and adjusting treatment accordingly.
