title: Changes of Respiratory Mechanics in COPD Patients from Stable State to Acute Exacerbations with Respiratory Failure.
abstract: Symptoms, clinical course, functional and biological data during an exacerbation of chronic obstructive pulmonary disease (EXCOPD) have been investigated, but data on physiological changes of respiratory mechanics during a severe exacerbation with respiratory acidosis requiring noninvasive mechanical ventilation (NIMV) are scant. The aim of this study was to evaluate changes of respiratory mechanics in COPD patients comparing data observed during EXCOPD with those observed during stable state in the recovery phase. In 18 COPD patients having severe EXCOPD requiring NIMV for global respiratory failure, we measured respiratory mechanics during both EXCOPD (T0) and once the patients achieved a stable state (T1). The diaphragm and inspiratory muscles effort was significantly increased under relapse, as well as the pressure-time product of the diaphragm and the inspiratory muscle (PTPdi and PTPes). The resistive loads to breathe (i.e., PEEPi,dyn, compliance and inspiratory resistances) were also markedly increased, while the maximal pressures generated by the diaphragm and the inspiratory muscles, together with forced expired volumes were decreased. All these indices statistically improved but with a great intrasubject variability in stable condition. Moreover, tension-time index (TTdi) significantly improved from the EXCOPD state to the condition of clinical stability (0.156 ± 0.04 at T0 vs. 0.082 ± 0.02 at T1 p < 0.001). During an EXCOPD, the load/capacity of the respiratory pump is impaired, and although the patients exhibit a rapid shallow breathing pattern, this does not necessarily correlate with a TTdi ≥ 0.15. These changes are reverted once they recover from the EXCOPD, despite a large variability between patients.
authors.affiliation: a Respiratory Rehabilitation Division, Salvatore Maugeri Foundation IRCCS, Institute of Pavia , Pavia , Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Ceriana
authors.affiliation: b Respiratory Rehabilitation Division, Salvatore Maugeri Foundation IRCCS, Institute of Lumezzane , Lumezzane , Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Vitacca
authors.affiliation: a Respiratory Rehabilitation Division, Salvatore Maugeri Foundation IRCCS, Institute of Pavia , Pavia , Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Carlucci
authors.affiliation: b Respiratory Rehabilitation Division, Salvatore Maugeri Foundation IRCCS, Institute of Lumezzane , Lumezzane , Italy.
authors.forename: Mara
authors.initials: M
authors.lastname: Paneroni
authors.affiliation: c Institute of Respiratory Diseases, Policlinico S. Orsola and Alma Mater University , Bologna , Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Pisani
authors.affiliation: c Institute of Respiratory Diseases, Policlinico S. Orsola and Alma Mater University , Bologna , Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Nava
mesh_terms: D000142:Acidosis, Respiratory / Q000209:etiology; D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D003964:Diaphragm / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D063087:Noninvasive Ventilation; D011312:Pressure; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D020127:Recovery of Function; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D015656:Respiratory Mechanics; D012720:Severity of Illness Index; D000067251:Symptom Flare Up; D013997:Time Factors; D014939:Work of Breathing
keywords: COPD; exacerbations; respiratory mechanics; respiratory muscles