title: Non-invasive determination of respiratory effort in spontaneous breathing and support ventilation: a validation study with healthy volunteers.
abstract: The proper setting of support ventilation aims to follow the patients' demands, ensuring adequate assistance to their respiratory effort. Effort assessment is thus necessary. But invasive procedures like measuring transdiaphragmatic pressure (Pdi) are impractical in long-term ventilation. Our purpose was therefore the development of the Occlusion+Delta (O+D) method for non-invasive continuous assessment of effort, quantified by the inspiratory pressure-time-product (PTPinsp), during ventilatory support. Flow and airway pressure were measured from 25 healthy volunteers at three effort levels. For the non-invasive method, short expiratory occlusions were executed each three to seven cycles to estimate resistance and compliance with a fitting algorithm fed with the differences between occluded and undisturbed cycles. Signals and estimates were then used to calculate the effort. For the validation of O+D, its estimations were compared to the results from invasive measurement of Pdi using balloon catheters. The agreement between PTPinsp from the invasive measurement and the proposed alternative was confirmed by regression analysis (PTP(O+D)=1.13PTP(Pdi)- 0.85, R²=0.84) and calculation of their differences (mean±SD=1.78±7.18 cm H2O s). Repeated execution of the non-invasive O+D method facilitates a safe automatic assessment of respiratory mechanics and breathing effort, promoting the rapid recognition of changes in patient's demands and the adaptation of support.
authors.forename: Kristel
authors.initials: K
authors.lastname: Lopez-Navas
authors.forename: Sebastian
authors.initials: S
authors.lastname: Brandt
authors.forename: Merle
authors.initials: M
authors.lastname: Strutz
authors.forename: Hartmut
authors.initials: H
authors.lastname: Gehring
authors.forename: Ullrich
authors.initials: U
authors.lastname: Wenkebach
mesh_terms: D000328:Adult; D000465:Algorithms; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009991:Oscillometry / Q000379:methods; D005082:Physical Exertion / Q000502:physiology*; D011175:Positive-Pressure Respiration / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000502:physiology*; D012680:Sensitivity and Specificity; D014939:Work of Breathing / Q000502:physiology*