Hypopnea

As hypopnea ( gr. Hypo (ὑπό) below; gr. Pnoe breath) an event during respiration is known in which there is a reduction of the respiratory flow.

On the other hand, if breathing is completely stopped for a longer or shorter period, one speaks of an apnea . These events occur in the context of respiratory regulation disorders such as sleep apnea syndrome or Cheyne-Stokes breathing .

Measurement and evaluation

To detect hypopneas, the nasal breath pressure is measured with the help of pressure sensors and pressure transducers . In addition, the measured values of an oximeter are required, since the oxygen saturation of the blood is also included in the evaluation of these respiratory events. In contrast, temperature sensors are sufficient to determine apneas.

Measurement and evaluation are carried out in the sleep laboratory as part of polysomnography and are based on the current recommendations of the American Society for Sleep Medicine (AASM).

The definition distinguishes between the following cases as a characteristic of hypopnea:

a reduction in respiratory flow by at least 30% of the initial value with at least 4% reduced oxygen saturation or
a reduction in respiratory flow by at least 50% of the initial value if either the oxygen saturation is reduced by at least 3% or the event is associated with an arousal .

The duration of the event must be at least ten seconds, whereby the values mentioned must be available for at least 90% of this time.

Apnea-Hypopnea Index

The number of these events and the number of apneas per hour of sleep are used as the apnea-hypopnea index (AHI) when assessing the severity of a “sleep-related breathing disorder”.

Due to differences in the evaluation of the hypopneas according to older rules and the two now valid rules to be used alternatively, there are considerable differences in the determination of the AHI with effects on the comparability of study results.

literature

American Academy of Sleep Medicine (Ed.): The AASM Manual for Scoring Sleep and Associated Events. Rules, technology and technical specifications . 1st edition. Steinkopff-Verlag, Heidelberg 2008, ISBN 978-3-7985-1851-3 . , note for hypopneas erratum

Individual evidence

↑ Conrad Iber, Sonia Ancoli-Israel, Andrew L. Chesson, Stuart F. Quan: The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications . Ed .: American Academy of Sleep Medicine. AASM, Westchester, Ill. 2007.
↑ Warren R. Rühland, Peter D. Rochford, Fergal J. O'Donoghue, Robert J. Pierce, Parmjit Singh, Andrew T. Thornton: The New AASM Criteria for scoring hypopneas: Impact on the apnea hypopnea index . In: Sleep . Vol. 32, No. 2 , 2009, p. 150–157 , PMC 2635578 (free full text) - (English).

[Scoring2007-1] Conrad Iber, Sonia Ancoli-Israel, Andrew L. Chesson, Stuart F. Quan: The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications . Ed .: American Academy of Sleep Medicine. AASM, Westchester, Ill. 2007.

[Ruehland2009-2] Warren R. Rühland, Peter D. Rochford, Fergal J. O'Donoghue, Robert J. Pierce, Parmjit Singh, Andrew T. Thornton: The New AASM Criteria for scoring hypopneas: Impact on the apnea hypopnea index . In: Sleep . Vol. 32, No. 2 , 2009, p. 150–157 , PMC 2635578 (free full text) - (English).