Comparison of pneumotachography and anemometery for flow measurement during mechanical ventilation with volatile anesthetics

Jarred R Mondoñedo; Jacob Herrmann; John S McNeil; David W Kaczka

doi:10.1007/s10877-016-9956-z

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Comparison of pneumotachography and anemometery for flow measurement during mechanical ventilation with volatile anesthetics

Journal article

Peer reviewed

Comparison of pneumotachography and anemometery for flow measurement during mechanical ventilation with volatile anesthetics

Jarred R Mondoñedo, Jacob Herrmann, John S McNeil and David W Kaczka

Journal of clinical monitoring and computing, Vol.31(6), pp.1263-1271

12/2017

DOI: 10.1007/s10877-016-9956-z

PMCID: PMC5429999

PMID: 27844299

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https://www.ncbi.nlm.nih.gov/pmc/articles/5429999View

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Abstract

Volatile anesthetics alter the physical properties of inhaled gases, such as density and viscosity. We hypothesized that the use of these agents during mechanical ventilation would yield systematic biases in estimates of flow ([Formula: see text]) and tidal volume (V ) for two commonly used flowmeters: the pneumotachograph (PNT), which measures a differential pressure across a calibrated resistive element, and the hot-wire anemometer (HWA), which operates based on convective heat transfer from a current-carrying wire to a flowing gas. We measured [Formula: see text] during ventilation of a spring-loaded mechanical test lung, using both the PNT and HWA placed in series at the airway opening. Delivered V was estimated from the numerically-integrated [Formula: see text]. Measurements were acquired under baseline conditions with room air, and during ventilation with increasing concentrations of isoflurane, sevoflurane, and desflurane. We also evaluated a simple compensation technique for HWA flow, which accounted for changes in gas mixture density. We found that discrepancies in estimated V between the PNT and HWA occurred during ventilation with isoflurane (6.3 ± 3.0%), sevoflurane (10.0 ± 7.3%), and desflurane (25.8 ± 17.2%) compared to baseline conditions. The magnitude of these discrepancies increased with anesthetic concentration. A simple compensation factor based on density reduced observed differences between the flowmeters, regardless of the anesthetic or concentration. These data indicate that the choice and concentration of anesthetic agents are primary factors for differences in estimated V between the PNT and HWA. Such discrepancies may be compensated by accounting for alterations in gas density.

Anesthetics

Flowmeters

Artificial respiration

Details

Title: Subtitle: Comparison of pneumotachography and anemometery for flow measurement during mechanical ventilation with volatile anesthetics
Creators: Jarred R Mondoñedo - Department of Biomedical Engineering and School of Medicine, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
Jacob Herrmann - Departments of Biomedical Engineering and Anesthesia, University of Iowa, Iowa City, IA, 52242, USA
John S McNeil - Department of Anesthesiology, University of Virginia Health System, PO Box 800710, Charlottesville, VA, 22908-0710, USA
David W Kaczka - Departments of Anesthesia, Biomedical Engineering, and Radiology, University of Iowa, 200 Hawkins Drive, Iowa City, IA, 52242, USA. david-kaczka@uiowa.edu
Resource Type: Journal article
Publication Details: Journal of clinical monitoring and computing, Vol.31(6), pp.1263-1271
DOI: 10.1007/s10877-016-9956-z
PMID: 27844299
PMCID: PMC5429999
NLM abbreviation: J Clin Monit Comput
ISSN: 1387-1307
eISSN: 1573-2614
Publisher: Netherlands
Grant note: UM1 HL108724 / NHLBI NIH HHS
Language: English
Date published: 12/2017
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Radiology; Anesthesia
Record Identifier: 9984007285202771

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