Συγκριτική αξιολόγηση της ανάλυσης Fourier και της πολλαπλής γραμμικής παλινδρόμησης για τη μελέτη των χρονικών μεταβολών της πίεσης και της ροής κατά τη διάρκεια μηχανικής αναπνοής

Abstract

Two linear methods for the analytical estimation of the respiratory system mechanicalparameters are compared the Multiple Linear Regression (MLR) and the Fourier Analysis(FA) This comparison refers to their competence and reliability during mechanical ventilationin 3 groups of patients a) without respiratory disorder b) with Chronic Obstructive PulmonaryDisease (COPD) and c) with acute respiratory distress syndrome (ARDS) Measurementswere applied in the usually applied range of ventilatory frequencies ((BF 0 17 0 33 Hz)externally applied positive end expiratory pressure (PEEP 0 10 hPa) Tidal volume (VT 300800 ml) before as well as after tracheotomy According to the results 1) The 2 methodsrevealed the differences of mechanical coefficients between the 3 studied groups of patientsElastance (Ers) Resistance (Rrs) Impedance (Zrs) Reactance (Xrs) phase angle betweenpressure and flow (Ors) time constant (Trs) and end expiratory pressure (EEP)) in allinstances accordingly 2) The two methods revealed clearly the influence of BF PEEP VTand tracheotomy on the mechanical parameters of the respiratory system 3) FA resultedgenerally to higher Ers Rrs Zrs Ors Trs and RMSD and to lower Xrs and EEP values thanMLR The higher differences between the 2 methods are noted in the ARDS & COPD groupsThis difference is influenced by the increase of BF PEEP and VTAlthough MLR depends on the total harmonic content of pressure & flow while FA is based onthe first harmonic term the two methods are equally reliable for revealing the underlyingpathophysiological respiratory disorder and the influence of BF PEEP VT and tracheotomyon the respiratory mechanics