Document Detail

Carbon dioxide elimination and gas displacement vary with piston position during high-frequency oscillatory ventilation.
MedLine Citation:
PMID:  15737246     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: Alterations in gas displacement in pediatric patients ventilated with the SensorMedics 3100A high-frequency oscillator are most commonly manipulated by adjusting the amplitude, frequency, and percent inspiratory time. The piston-position-and-displacement indicator is commonly centered and subsequently not adjusted. That practice may limit the clinician's ability to optimize carbon dioxide elimination. We hypothesized that varying the piston position would alter gas displacement and carbon dioxide elimination. METHODS: We conducted an observational study in a tertiary pediatric intensive care unit and a correlated bench study. In the clinical study, 24 patients were ventilated with a SensorMedics 3100A high-frequency oscillator. Transcutaneously measured carbon dioxide ((tCO(2))) values were documented with the piston-position-and-displacement indicator in left, center, and right positions. In the bench study the oscillator was set and maintained at: mean airway pressure 15 cm H(2)O, inspiratory time 33% of respiratory-cycle time, bias flow 20 L/min. A pneumotachometer attached to a respiratory mechanics monitor was placed between the ventilator circuit and a test lung. Data were collected with the piston-position-and-displacement indicator at the left, center, and right positions with frequencies of 4-14 Hz and amplitudes of 25-55 cm H(2)O. Data were collected over a 3-minute time period for each combination of frequency, amplitude, and piston-position-and-displacement-indicator position. We compared the data with repeated-measures analysis of variance. Pairwise comparisons were performed with a 2-tailed Student's test with Bonferroni correction. RESULTS: Among the 24 patients (tCO(2)) was significantly associated with the position of the piston (p < 0.007). In the bench study, gas displacement was higher when the piston-position-and-displacement indicator was positioned to the left (than when at the center position) 91.7% of the time (p < 0.0001). When the piston-position-and-displacement indicator was positioned to the right (as compared to the center position), gas displacement was lower 75% of the time (p < 0.0001). CONCLUSION: Adjusting the oscillator piston alters the volume of gas displaced and provides an additional means for titrating carbon dioxide elimination. .
Donna S Hamel; Andrew L Katz; Damian M Craig; John D Davies; Ira M Cheifetz
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article    
Journal Detail:
Title:  Respiratory care     Volume:  50     ISSN:  0020-1324     ISO Abbreviation:  Respir Care     Publication Date:  2005 Mar 
Date Detail:
Created Date:  2005-03-01     Completed Date:  2005-07-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7510357     Medline TA:  Respir Care     Country:  United States    
Other Details:
Languages:  eng     Pagination:  361-6     Citation Subset:  IM    
Department of Pediatric Critical Care Medicine, Duke University Medical Center, Box 3046, Durham NC 27710, USA.
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MeSH Terms
Carbon Dioxide / pharmacokinetics*
Child, Preschool
Equipment Design
High-Frequency Ventilation / instrumentation*,  methods*
Infant, Newborn
Pulmonary Gas Exchange*
Respiratory Insufficiency / therapy
Reg. No./Substance:
124-38-9/Carbon Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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