Thermistor Qualitative signal Measurement of the temperature of inspired and expired airflow No linear correlation with ventilation Unreliable for hypopnea detection

Nasal cannula Curvilinear relationship between pressure and flow Good sensitivity to detect hypopnea and flow limitation Mouth opening reduces performance

Measuring oronasal airflow Thermistors : monitor temperature, not flow Nasal cannulae : P~ V² 3

Inductive Plethysmography Quantitative: requires titration, can’t last overnight Semi-quantitative: reliable for clinical use

Piezo sensors and strain gauges Qualitative In hypopnea detection should be linked to other signals To be placed where maximal excursion of thorax and abdomen are detected

Continuous Snoring Intermittent Snoring

Hernandez, L. et al. Chest 2001;119:442-450

Nasal cannula Normal flow Flow limitation Mouth opening Cardiogenic oscillations (central apnea)

10

11

12

13

Thoraco-abdominal Movements Paradoxical Movements Movements in phase

EEG O1A2 EEG C3A2 EOG sx EOG dx EMG ECG flow thorax abd. SaO2

18

20

21

22

23

Hypopnea

25

26

27

28

29

30

Hernandez, L. et al. Chest 2001;119:442-450 Different sensors give different information Hernandez, L. et al. Chest 2001;119:442-450

32

RERA Flow limitation

34

36