What is the recommended decrease in SPO2 needed for an event to be scored as a central apnea?

In the context of scoring central apneas during polysomnography, the key factor is that central apneas are characterized by the absence of respiratory effort, rather than a specific decrease in oxygen saturation (SpO2). Unlike obstructive apneas, where a significant decrease in SpO2 is typically observed due to the blockage of airflow despite ongoing efforts to breathe, central apneas occur when the brain temporarily stops sending signals to the muscles that control breathing.

For a central apnea event to be scored, it is not essential to have a particular decrease in SpO2. Thus, the definition inherently allows for the scoring of an event based solely on the cessation of breathing effort for a specified duration (usually at least 10 seconds) without the necessity of a defined hypoxemic threshold. This is why no required decrease in SpO2 is the correct definition for scoring central apneas.

The other options suggest specific percentages that imply a threshold for scoring, which does not apply to central apneas since they are identified based on the lack of respiratory effort, irrespective of saturation levels.