Averaging time, desaturation level, duration and extent

Arch Dis Child Fetal Neonatal Ed. 2013 May;98(3):F265-6. doi: 10.1136/archdischild-2012-302543. Epub 2012 Sep 8.


Background: Pulse oximeter saturation values are usually obtained by averaging over preceding measurements. This study investigates the dynamics between the averaging time and desaturation level, duration and extent.

Methods and results: Prospective observational study of 15 preterm infants. Oxygen saturation was recorded for 168 h using a pulse oximeter. The raw red-to-infrared data were reprocessed using seven different averaging times to determine the number of desaturations below four thresholds and for seven different minimal desaturation durations. The total number of desaturations <80% was 339 with an averaging time of 16 s and 1958 with an averaging time of 3 s (minimal event duration >0 s). There was a significantly lower pulse oximeter saturation nadir with the shorter averaging time, while the maximum duration was significantly longer when using a 16 s averaging time.

Conclusions: When using pulse oximeters, more attention should be given to averaging time and duration of desaturations.

MeSH terms

  • Apnea / physiopathology*
  • Humans
  • Infant, Newborn
  • Infant, Premature / physiology*
  • Infant, Premature, Diseases / physiopathology*
  • Oximetry / methods*
  • Oxygen / physiology*
  • Prospective Studies
  • Time Factors


  • Oxygen