Related Experiment Video
Updated: Apr 5, 2026

A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Non-linear Poincaré analysis of respiratory efforts in sleep apnea
Objectives:
Obstructive sleep apnea (OSA) is a risk factor for hypertension, has effects on cardiovascular system and increases the sympathetic activity. The aim of the study was to evaluate the effectiveness of the non-linear Poincaré plot analysis to predict OSA based on polysomnography (PSG).
Methods:
The database of this study was collected by the sleep laboratory at the Philipps University in Marburg, Germany. It includes 24 PSG of men and women between 27-63 years old with obstructive and mixed sleep apnea. The start and end of apnea events in PSGs were marked. The Poincaré plots of pre-apneic phase including 4-1 minutes before apnea were evaluated. Wilcoxon test was used for statistical analysis.
Results:
Poincaré analysis showed that the dynamics of chest and respiratory efforts changed two minutes before the apnea and SD1/SD2 ratios of these parameters significantly increased in the pre-apneic phase (p≤0.01). The SD1/SD2 ratio of nasal airflow did not show significant difference even in episodes close to apnea.
Conclusions:
Our results suggest that Poincaré plot parameters of PSG have the potential to be considered predictors of apnea with the ability to show the dynamic of changes, which could lead to pre-diagnosis or prediction of apnea about 2-3 minutes before its occurrence (Tab. 2, Fig. 4, Ref. 23).
More Related Videos
Related Concept Videos
Sleep Apnea
The condition is more prevalent among...
Respiratory Volumes and Capacities I
Alterations in Respiration II
In Biot's breathing, the respiratory rate and depth are irregular, alternating between periods of deep gasping and apnea. Common causes...
Physical Assessment of the Respiratory Tract II: Inspection
Chest Configuration
The chest configuration...
Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
Acute Respiratory Failure-IV

