| Respiratory Mechanics During High Frequency Oscillatory Ventilation: A Physical Model and Preterm Infant Study. | |
| | |
MedLine Citation:
|
PMID: 22207721 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
|
Accurate mechanics measurements during high frequency oscillatory ventilation (HFOV) facilitate optimizing ventilator support settings. Yet, these are substantially influenced by endotracheal tube (ETT) contributions which may dominate when leaks around uncuffed ETT are present. We hypothesized that 1) the effective removal of ETT leaks may be confirmed via direct comparison of measured versus model-predicted mean intra-tracheal pressure (mPtr); and 2) reproducible respiratory system resistance (Rrs) and compliance (Crs) may be derived from no-leak, oscillatory Ptr and proximal flow. Using ETT - test lung models, proximal (Pao) and distal (Ptr) pressures and flows were measured during slow cuff inflations until leaks are removed. These were repeated for combinations of HFOV settings [Frequency, mean-airway-pressure (Paw), oscillation amplitudes (ΔP) and inspiratory time (%t(I))] and varying Test-Lung compliance. Results showed that leaks around the ETT will 1) systematically reduce the effective distending pressures and lung-delivered oscillatory volumes, and 2) derived mechanical properties are increasingly non-physiologic as leaks worsen. Mean pressures were systematically reduced along the ventilator circuit and ETT (Paw> Pao>Ptr) even for no leak conditions. ETT size-specific regression models were then derived for predicting mPtr based on: mean Pao, ΔPao, %t(I) and Frequency. Next, in 10 of 11 studied preterm infants (0.77±0.24 kg), no-to-minimal leak was confirmed based on excellent agreement between measured and model-predicted mPtr and, consequently, their oscillatory respiratory mechanics were evaluated. Infant resistance at the proximal ETT (Rao=R(ETT)+Rrs; p<0.001) and ETT inertance (I(ETT); p=0.014) increased significantly with increasing oscillation amplitude (ΔP = 50%, 100% and 150% baseline) whereas Rrs showed a modest non-significant increase (p=0.14) and Crs was essentially unchanged (p=0.39). We conclude that verifying no-leak conditions is feasible by comparison of model-derived versus measured mean distending Ptr. This facilitated the reliable and accurate assessment of physiologic respiratory mechanical properties that can objectively guide ventilatory management of HFOV-treated preterm infants. |
| | |
Authors:
|
Rachana Singh; Sherry E Courtney; Michael D Weisner; Robert H Habib |
Publication Detail:
|
Type: JOURNAL ARTICLE Date: 2011-12-29 |
Journal Detail:
|
Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Dec |
Date Detail:
|
Created Date: 2011-12-30 Completed Date: - Revised Date: - |
Medline Journal Info:
|
Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
|
Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
|
1Baystate Medical Center. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Drought Responses of Leaf Tissues from Wheat Cultivars of Differing Drought Tolerance at the Metabol...
Next Document: Assessment of locomotion in chlorine exposed mice by computer vision and neural networks.