A new adaptive controller for volume-controlled mechanical ventilation in small animals. (1st May 2014)

• Record Type: Journal Article
• Authors: Huhle, Robert; Spieth, Peter M.; Güldner, Andreas; Koch, Thea; Abreu, Marcelo Gama de
• Is Part Of: Experimental lung research. Volume 40:Number 4(2014)
• Page Start: 186
• Page End: 197
• Publication Date: 2014-05-01
• Subjects: Lungs -- Periodicals; Lungs -- Diseases -- Periodicals; Lung Diseases; Lung -- physiology; Respiratory System; 616.24
• DOI: 10.3109/01902148.2014.900156
• Languages: English
• ISSNs: 0190-2148

Abstract

<abstract> <title>ABSTRACT</title> <p> <italic>Background</italic>: This study aimed to develop and evaluate an adaptive control system for volume-controlled ventilation (VCV) in small animals to guarantee accurate delivery of tidal volume (<italic>V</italic><sub>T</sub>) in the presence of changes in lung mechanics. <italic>Methods</italic>: The adaptive control system to control the Harvard Inspira ventilator was designed and evaluated on a custom-made physical model during step changes of resistance and elastance of the respiratory system assessing difference in minute ventilation (ΔMV<sub>c</sub>) during convergence cycles (<italic>N</italic><sub>C</sub>). The controller was then evaluated during conventional and variable volume VCV in rats with acute respiratory distress syndrome (ARDS) induced by intratracheal HCl (six animals/group), where the difference between desired and applied <italic>V</italic><sub>T</sub> (d<italic>V</italic><sub>T</sub><sub>, d</sub>), its root-mean square error (RMSE) and relative deviation from target minute ventilation (ΔMV) were determined. <italic>Results</italic>: The controller showed fast convergence <italic>N</italic><sub>C</sub> < 20 cycles with an acceptable ΔMV<sub>C</sub> < 10% in simulations and nearly abolished d<italic>V</italic><sub>T</sub><sub>, d</sub> (VCV: 0.23 ± 0.1 mL to 0.0 ± 0.0 mL, <italic>P</italic> < .001 and v<italic>V</italic>CV: 0.05 ± 0.8 mL to 0.0 ± 0.0 mL, <italic>P</italic> < .001), significantly reduced RMSE (VCV: 0.23 ± 0.1 to 0.04 ± 0.01 mL, <italic>P</italic> < .001 and <italic>v</italic>VCV: 0.13 ± 0.04 to 0.08 ± 0.02 mL, <italic>P</italic> < .001) and ΔMV (VCV: 11.6 ± 4.2 to 0.04 ± 0.15%, <italic>P</italic> < .001 and <italic>v</italic>VCV: −3 ± 3.8 to −0.35 ± 1.3 %, <italic>P</italic> < .001) in animal experiments. In VCV the improvement was more pronounced, due to reduced respiratory system elastance in this group (VCV: 5.6 cmH<sub>2</sub>O mL<sup>−1</sup> versus <italic>v</italic>VCV: 3.8 cmH<sub>2</sub>O mL<sup>−1</sup>, <italic>P</italic> < .001). <italic>Conclusions</italic>: The new adaptive controller ensured accurate delivery of <italic>V</italic><sub>T</sub> in VCV and proved valuable for mechanical ventilation of small animals especially in ARDS research.</p> </abstract>