title: Pulse transit time as a measure of respiratory effort under noninvasive ventilation.
abstract: Among the respiratory events that may occur during nocturnal noninvasive ventilation (NIV), differentiating between central and obstructive events requires appropriate indicators of respiratory effort. The aim of the present study was to assess pulse transit time (PTT) as an indicator of respiratory effort under NIV in comparison with oesophageal pressure (P(oes)). During wakefulness, PTT was compared to P(oes) during spontaneous breathing and under NIV with or without induced leaks in 11 healthy individuals. In addition, the contribution of PTT versus P(oes) to differentiation of central from obstructive respiratory events occurring under NIV during sleep was evaluated in 10 patients with obesity hypoventilation syndrome (OHS). From spontaneous breathing to NIV without leaks, respiratory effort decreased significantly whereas, with increasing level of leaks, there was a significant increase in respiratory effort. Changes in PTT accurately reflected changes in P(oes). In OHS patients during nocturnal NIV, intraclass correlation coefficients between P(oes) and PTT were 0.970 for total number of events and 0.970 for percentage of central events. PTT accurately reflects the unloading of respiratory muscles induced by NIV and the increase in respiratory effort during leaks. PTT during sleep is also useful to differentiate central from obstructive respiratory events occurring under NIV.
authors.affiliation: Division of Pulmonary Diseases, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Contal
authors.forename: Claudio
authors.initials: C
authors.lastname: Carnevale
authors.forename: Jean-Christian
authors.initials: JC
authors.lastname: Borel
authors.forename: AbdelKébir
authors.initials: A
authors.lastname: Sabil
authors.forename: Renaud
authors.initials: R
authors.lastname: Tamisier
authors.forename: Patrick
authors.initials: P
authors.lastname: Lévy
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Janssens
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Pépin
mesh_terms: D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D016022:Case-Control Studies; D004947:Esophagus / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D063087:Noninvasive Ventilation / Q000379:methods*; D010845:Obesity Hypoventilation Syndrome / Q000175:diagnosis; D010092:Oximetry / Q000379:methods; D063177:Pulse Wave Analysis / Q000379:methods*; D015203:Reproducibility of Results; D012119:Respiration; D012815:Signal Processing, Computer-Assisted; D012890:Sleep; D055815:Young Adult