Archive: Mar 2020

System Design Verification for Closed Loop Control of Oxygenation With Concentrator Integration

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Abstract

BACKGROUND:

Addition of an oxygen concentrator into a control loop furthers previous work in autonomous control of oxygenation. Software integrates concentrator and ventilator function from a single control point, ensuring maximum efficiency by placing a pulse of oxygen at the beginning of the breath. We sought to verify this system. Methods: In a test lung, fraction of inspired oxygen (FIO2) levels and additional data were monitored. Tests were run across a range of clinically relevant ventilator settings in volume control mode, for both continuous flow and pulse dose flow oxygenation. Results: Results showed the oxygen concentrator could maintain maximum pulse output (192 mL) up to 16 breaths per minute. Functionality was verified across ranges of tidal volumes and respiratory rates, with and without positive end-expiratory pressure, in continuous flow and pulse dose modes. For a representative test at respiratory rate 16 breaths per minute, tidal volume 550 mL, without positive end-expiratory pressure, pulse dose oxygenation delivered peak FIO2 of 76.83 ± 1.41%, and continuous flow 47.81 ± 0.08%; pulse dose flow provided a higher FIO2 at all tested setting combinations compared to continuous flow (p < 0.001). Conclusions: These tests verify a system that provides closed loop control of oxygenation while integrating time-coordinated pulse-doses from an oxygen concentrator. This allows the most efficient use of resources in austere environments.

METHODS:

In a test lung, fraction of inspired oxygen (FIO2) levels and additional data were monitored. Tests were run across a range of clinically relevant ventilator settings in volume control mode, for both continuous flow and pulse dose flow oxygenation.

RESULTS:

Results showed the oxygen concentrator could maintain maximum pulse output (192 mL) up to 16 breaths per minute. Functionality was verified across ranges of tidal volumes and respiratory rates, with and without positive end-expiratory pressure, in continuous flow and pulse dose modes. For a representative test at respiratory rate 16 breaths per minute, tidal volume 550 mL, without positive end-expiratory pressure, pulse dose oxygenation delivered peak FIO2 of 76.83 ± 1.41%, and continuous flow 47.81 ± 0.08%; pulse dose flow provided a higher FIO2 at all tested setting combinations compared to continuous flow (p < 0.001).

CONCLUSIONS:

These tests verify a system that provides closed loop control of oxygenation while integrating time-coordinated pulse-doses from an oxygen concentrator. This allows the most efficient use of resources in austere environments.

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Authors: Thomas C. Blakeman (a) , Jay A. Johannigman (a,b), Matthew M. Gangidine (a,b), Richard D. Branson (a)
(a) University of Cincinnati Department of Surgery, Division of Trauma/Critical Care; Cincinnati, OH, United States
(b) Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814.

System Design Verification for Closed Loop Control of Oxygenation With Concentrator Integration (pdf)

Physiorack: An integrated MRI safe/conditional, Gas delivery, respiratory gating, and subject monitoring solution for structural and functional assessments of pulmonary function

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Abstract

Purpose

To evaluate the use of a modular MRI conditional respiratory monitoring and gating solution, designed to facilitate proper monitoring of subjects’ vital signals and their respiratory efforts, during free‐breathing and breathheld 19F, oxygen‐enhanced, and Fourier‐decomposition MRI‐based acquisitions.

 

Materials and Methods

All Imaging was performed on a Siemens TIM Trio 3 Tesla MRI scanner, following Institutional Review Board approval. Gas delivery is accomplished through the use of an MR compatible pneumotachometer, in conjunction with two three‐way pneumatically controlled Hans Rudolph Valves. The pneumatic valves are connected to Douglas bags used as the gas source. A mouthpiece (+nose clip) or an oro‐nasal Hans Rudolph disposable mask is connected following the pneumatic valve to minimize dead‐space and provide an airtight seal. Continuous monitoring/sampling of inspiratory and expiratory oxygen and carbon dioxide levels at the mouthpiece/mask is achieved through the use of an Oxigraf gas analyzer.

Results

Forty‐four imaging sessions were successfully monitored, during Fourier‐decomposition (n = 3), fluorine‐enhanced (n = 29), oxygen‐enhanced, and ultra short echo (n = 12) acquisitions. The collected waveforms, facilitated proper monitoring and coaching of the subjects.

Conclusion

We demonstrate an inexpensive, off‐the‐shelf solution for monitoring these signals, facilitating assessments of lung function. Monitoring of respiratory efforts and exhaled gas concentrations assists in understanding the heterogeneity of lung function visualized by gas imaging. J. Magn. Reson. Imaging 2014;39:735–741. © 2013 Wiley Periodicals, Inc.

Authors: Ahmed F. Halaweish, PhD and H. Cecil Charles, PhD: Duke Image Analysis Laboratory and Department of Radiology, Duke University School of Medicine, Durham, North Carolina, USA,

Physiorack: An integrated MRI safe/conditional, Gas delivery, respiratory gating, and subject monitoring solution for structural and functional assessments of pulmonary function (pdf)