RT Journal Article
SR Electronic
T1 The Spontaneous Breathing Pattern and Work of Breathing of Patients With Acute Respiratory Distress Syndrome and Acute Lung Injury
JF Respiratory Care
FD American Association for Respiratory Care
SP 989
OP 995
VO 52
IS 8
A1 Kallet, Richard H
A1 Hemphill, J Claude
A1 Dicker, Rochelle A
A1 Alonso, James A
A1 Campbell, Andre R
A1 Mackersie, Robert C
A1 Katz, Jeffrey A
YR 2007
UL http://rc.rcjournal.com/content/52/8/989.abstract
AB BACKGROUND: The spontaneous breathing pattern and its relationship to compliance, resistance, and work of breathing (WOB) has not been examined in patients with acute respiratory distress syndrome (ARDS) or acute lung injury (ALI). Clinically, the ratio of respiratory frequency to tidal volume (f/VT) during spontaneous breathing may reflect adaptation to altered compliance, resistance, and increased WOB. We examined the relationship between f/VT, WOB, and respiratory system mechanics in patients with ARDS/ALI. METHODS: Data from spontaneous breathing trials were collected from 33 patients (20 with ARDS, 13 with ALI) at various points in their disease course. WOB and respiratory system mechanics were measured with a pulmonary mechanics monitor that incorporates Campbell diagram software. Differences between the patients with ARDS and ALI were assessed with 2-sided unpaired t tests. Multivariate linear regression models were constructed to assess the relationship between f/VT and other pulmonary-related variables. RESULTS: Patients with ARDS had significantly lower compliance than those with ALI (24 ± 6 mL/cm H2O vs 40 ± 13 mL/cm H2O, respectively, p < 0.001), but this did not translate into significant differences in either WOB (1.70 ± 0.59 J/L vs 1.43 ± 0.90 J/L, respectively, p = 0.30) or f/VT (137 ± 82 vs 107 ± 49, respectively, p = 0.23). Multivariate linear regression modeling revealed that peak negative esophageal pressure, central respiratory drive, duration of ARDS/ALI, minute ventilation deficit between mechanical ventilation and spontaneous breathing, and female gender were the strongest predictors of f/VT. CONCLUSION: The characteristic rapid shallow breathing pattern in patients with ARDS/ALI occurs in the context of markedly diminished compliance, elevated respiratory drive, and increased WOB. That f/VT had a strong, inverse relationship to peak negative esophageal pressure also may reflect the influence of muscle weakness.