Final answer:
The improvement in a patient's SpO2 from 90% to 99% after oxygen therapy would be documented in the 'E: Evaluation' category of the CHEATED documentation method.
Step-by-step explanation:
When documenting the improvement of a patient’s SpO2 level from 90% to 99% after oxygen therapy using the CHEATED method, the correct category for this information would be E: Evaluation. This category is where the effectiveness of a treatment or intervention is recorded, showing the patient's response to the oxygen therapy.
The rise in SpO2 indicates a positive outcome, reflecting an increase in the percent saturation of hemoglobin with oxygen, which is a crucial assessment in monitoring a patient's oxygenation status. According to the information provided, the patient's SpO2 improves from 90% to 99% after oxygen therapy. The CHEATED method of documentation categorizes this information under the E: Evaluation category.