Search

Exacerbations are part of the natural history of chronic obstructive pulmonary disease and asthma. Severe exacerbations can cause acute respiratory failure, which may ultimately require mechanical ventilation. This review summarizes practical ventilator strategies for the management of patients with obstructive airway disease. Such strategies include non-invasive mechanical ventilation to prevent intubation, invasive mechanical ventilation, from the time of intubation to weaning, and strategies intended to prevent post-extubation acute respiratory failure. The role of tracheostomy, the long-term prognosis, and potential future adjunctive strategies are also discussed. Finally, the physiological background that underlies these strategies is detailed., Author(s): Alexandre Demoule [sup.1] [sup.2], Laurent Brochard [sup.3] [sup.4], Martin Dres [sup.1] [sup.2], Leo Heunks [sup.5], Amal Jubran [sup.6], Franco Laghi [sup.6], Armand Mekontso-Dessap [sup.7] [sup.8], Stefano Nava [sup.9], Lamia [...]

Background During exercise-training patients with chronic obstructive pulmonary disease (COPD) can entrain their breathing pattern to visual-feedback cues as to achieve a slower respiratory rate and prolong exhalation. The result is an improvement in exercise tolerance and a reduction in dynamic hyperinflation. Acoustic stimuli, including metronome-generated acoustic stimuli, can entrain human movements. Accordingly, we hypothesized that exercise duration and dynamic hyperinflation would be less after exercise-training plus breathing-retraining using a metronome-based acoustic-feedback system than after exercise-training alone. Methods Of 205 patients with COPD [FEV.sub.1 = 44 ± 16% predicted (± SD)] recruited, 119 were randomly assigned to exercise-training plus breathing-retraining using acoustic feedback (n = 58) or exercise-training alone (n = 61). Patients exercised on a treadmill thrice-weekly for 12 weeks. Before and at completion of training, patients underwent constant-load treadmill testing with inspiratory capacity measures every 2 min. Results At completion of training, improvements in exercise duration in the breathing-retraining plus exercise-training and exercise-training alone groups were similar (p = 0.35). At isotime, inspiratory capacity increased (less exercise-induced dynamic hyperinflation) by 3% (p = 0.001) in the breathing-retraining plus exercise-training group and remained unchanged in the exercise-alone group. The between-group change in inspiratory capacity, however, was not significant (p = 0.08). Conclusions In patients with COPD, breathing-retraining using a metronome-based acoustic feedback did not result in improved exercise endurance or decreased dynamic hyperinflation when compared to exercise-training alone. Trial registry: ClinicalTrials.gov; No.: NCT NCT01009099; URL: http://www.clinicaltrials.gov http://www.clinicaltrials.gov, Author(s): Eileen G. Collins [sup.1] [sup.2] , Christine Jelinek [sup.2] , Susan O'Connell [sup.2] , Jolene Butler [sup.2] , Domenic Reda [sup.3] [sup.4] , Franco Laghi [sup.5] [sup.6] Author Affiliations: [...]

Purpose Ultrasound measurements of diaphragm thickness (T.sub.di) and thickening (TF.sub.di) may be useful to monitor diaphragm activity and detect diaphragm atrophy in mechanically ventilated patients. We aimed to establish the reproducibility of measurements in ventilated patients and determine whether passive inflation by the ventilator might cause thickening apart from inspiratory effort. Methods Five observers measured T.sub.di and TF.sub.di in 96 mechanically ventilated patients. The probe site was marked in 66 of the 96 patients. TF.sub.di was measured at peak and end-inspiration (airway occluded and diaphragm relaxed) in nine healthy volunteers inhaling to varying lung volumes. The association with diaphragm electrical activity was quantified. Results Right hemidiaphragm thickness was obtained on 95 % of attempts; left hemidiaphragm measurements could not be obtained consistently. Right hemidiaphragm thickness measurements were highly reproducible (mean ± SD 2.4 ± 0.8 mm, repeatability coefficient 0.2 mm, reproducibility coefficient 0.4 mm), particularly after marking the location of the probe. TF.sub.di measurements were only moderately reproducible (median 11 %, IQR 3-17 %, repeatability coefficient 17 %, reproducibility coefficient 16 %). TF.sub.di and diaphragm electrical activity were positively correlated, r.sup.2 = 0.32, p < 0.01). At inspiratory volumes below 50 % of inspiratory capacity, passive inflation did not cause diaphragm thickening. TF.sub.di was considerably lower in patients on either partially assisted or controlled ventilation compared to healthy subjects (median 11 vs. 35 %, p < 0.001). Conclusions Ultrasound measurements of right hemidiaphragm thickness are feasible and highly reproducible in ventilated patients. At clinically relevant inspiratory volumes, diaphragm thickening reflects muscular contraction and not passive inflation. This technique can be reliably employed to monitor diaphragm thickness, activity, and function during mechanical ventilation., Author(s): Ewan C. Goligher [sup.1] [sup.2] [sup.3], Franco Laghi [sup.4], Michael E. Detsky [sup.1] [sup.5], Paulina Farias [sup.2], Alistair Murray [sup.2], Deborah Brace [sup.2], Laurent J. Brochard [sup.1] [sup.6], Steffen [...]

Because the diaphragm is essential for survival, we wondered if it might be less vulnerable to the long-lasting effects of fatigue than limb muscles. Using a recently introduced magnetic probe to activate the phrenic nerves, we followed the evolution of twitch transdiaphragmatic pressure after inducing fatigue in healthy volunteers. Twenty-four hours after its induction, diaphragmatic fatigue had not fully recovered. Findings from this study later served as the foundation for incorporating a once-daily, T-tube-trial arm into a randomized controlled trial of techniques for ventilator weaning in intensive care unit patients and also influenced the design of a controlled trial of the weaning of tracheostomy patients who required prolonged ventilation. The research methodology was later employed to determine whether low-frequency fatigue is responsible for weaning failure. Employing a further modification of the technique-twitch airway pressure-it became evident that respiratory muscle weakness is a greater problem than fatigue in ventilated patients. Twitch airway pressure is now being used to document the prevalence and consequences of ventilator-induced respiratory muscle weakness. Our study-which began with a circumscribed, simple question-has yielded dividends in unforeseen directions, illustrating the fruitfulness of research into basic physiological mechanisms., Author(s): Franco Laghi [sup.1] [sup.2], Nausica D'Alfonso [sup.1] [sup.2], Martin J. Tobin [sup.1] [sup.2] Author Affiliations: (1) grid.280893.8, 0000000404195175, Division of Pulmonary and Critical Care Medicine, Edward Hines, Jr. VA [...]