Low-Cost Differential Pressure Spirometry for Emergency Ventilator Tidal Volume Sensing

Edmunds, Jordan L.; Bustamante, Mauricio J.; Raymond, Samuel; Camarillo, David B.; Piech, David K.; Schor, Jonathan S; Maharbiz, Michel M.

doi:10.1101/2020.09.25.20198069

Cited by 3 publications

(10 citation statements)

References 7 publications

(10 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, it should be noted that other authors [27], [29] reported a maximum error between 4% and 5%, when accurately considering all the model variables or applying several regression models. Others [35] have used a single k value for the entire flow range, nevertheless presenting a substantial error for low flow estimation. Our novel method presents various advantages compared to previous methods and an average relative error of up to 4.86%.…”

Section: Discussionmentioning

confidence: 99%

“…The airflow is regulated and captured in intervals of approximately 1 L/min, starting from 1 and up to 40 L/min; subsequently, then increasing by intervals of 5 L/min until reaching the sensor saturation point, which is around 80 L/min in our case. The data capture occurs in intervals of 1 L/min in the range of 1 L/min up to 40 L/min to reduce the error reported for low-flow estimation [27], [35]. Flow values between 1 and 20 L/min are used as triggers in ventilatory assistance; therefore, having a reasonable estimation of these values is very important.…”

Section: B Proposed Calibration Methodsmentioning

confidence: 99%

“…In dotted lines, the connections necessary in calibration mode, where the gas analyzer sends the flow (Q) value to the computer . complicated [27], [35]. The discharge coefficient C d is a function of the Reynolds number and the relationship between the area through which the flow Q passes and the area obstructed by the ports.…”

Section: Theorymentioning

confidence: 99%

“…The test consisted of varying the respiratory rate (BPM), the I:E ratio, and the tidal volume to obtain a flow value considered constant that was controlled throughout the ventilatory cycle. test compared the dichotomous flow algorithm method with the PF-300 gas analyzer measurement and with the regression model in D-lite with only one k value [35].…”

Section: Error Test Based On Flowmentioning

confidence: 99%

See 3 more Smart Citations

Differential Pressure Spirometry for Mechanical Ventilation Using Dichotomic Search

Rodríguez-Olivares

Nava-Balanzar

Barriga-Rodríguez

2021

IEEE Trans. Instrum. Meas.

View full text Add to dashboard Cite

In invasive mechanical ventilation (IMV), it is critical that the flow value is estimated correctly, as it is used as a trigger variable for ventilatory assistance. Furthermore, the numerical integration of the flow allows the calculation of the total volume per breath (tidal volume), which clinicians use to identify trauma or lung capacity in the patient. The current COVID-19 pandemic has demonstrated the need to develop safe and efficient techniques for measuring this spirometry variable because many mechanical ventilators delivered to hospitals were unable to measure it directly. A good device to estimate flow is a D-lite sensor, which works by the Venturi effect, is cheap, reusable, and proximal to the patient. However, the regressions applied to the flow estimation model are limited for use in real conditions. This article presents a flow estimation method that uses a D-Lite device, a fraction of inspired oxygen (FiO2) cell, and two pressure sensors as critical items. Our novel method adapts the dichotomous search algorithm instead of conventional regression algorithms to estimate flow using a D-lite sensor; this change in the standard procedure allowed us a fast calibration process, a good low-flow estimation, and low computational time for flow estimation. The method was validated experimentally to compute the tidal volume according to the measurement requirement error range of +/-10%. The consideration of FiO2 percentage in the gas mixture and the good low-flow estimation make this novel method useful for real ventilation conditions. The flow calculations have been performed at different ambient conditions and compared with gas analyzers show an average relative error of up to 4.86%. Finally, we present an analysis of the error flow estimation considering the variation in each variable. Technical recommendations for applying this novel method to achieve invasive mechanical ventilation safely are presented, based on the capabilities of the embedded system used by developers.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: B Proposed Calibration Methodsmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Error Test Based On Flowmentioning

confidence: 99%

See 2 more Smart Citations

Differential Pressure Spirometry for Mechanical Ventilation Using Dichotomic Search

Rodríguez-Olivares

Nava-Balanzar

Barriga-Rodríguez

2021

IEEE Trans. Instrum. Meas.

View full text Add to dashboard Cite

show abstract

“…Volume calculations are still important for patient care, so in addition to this table for setting the desired delivered volume, a spirometer-based expiratory volume sensor is used on the expiration side of the circuit to measure exhaled volumes. This spirometer-based volume sensor is based on the work of Edmunds et.al [12], who’s work was aimed to help measure gas volumes in ventilators for the COVID-19 pandemic. The O2U ventilator prototype is shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

A low-cost, rapidly scalable, emergency use ventilator for the COVID-19 crisis

Raymond¹,

Wesolowski²,

Baker

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

For the past 50 years, positive pressure ventilation has been a cornerstone of treatment for respiratory failure. Consensus surrounding the epidemiology of respiratory failure has permitted a relatively good fit between the supply of ventilators and the demand. However, the current COVID-19 pandemic has increased demand for mechanical ventilators well beyond supply. Respiratory failure complicates most critically ill patients with COVID-19 and is characterized by highly heterogeneous pulmonary parenchymal involvement, profound hypoxemia and pulmonary vascular injury. The profound increase in the incidence of respiratory failure has exposed critical shortages in the supply of mechanical ventilators, and those with the necessary skills to treat. While most traditional ventilators rely on an internal compressor and mixer to moderate and control the gas mixture delivered to a patient, the current emergency climate has catalyzed alternative designs that might enable greater flexibility in terms of supply chain, manufacturing, storage and maintenance. Design considerations of these 'emergency response' ventilators have generally fallen into two categories: those that rely on mechanical compression of a known volume of gas and those powered by an internal compressor to deliver time cycled pressure- or volume-limited gas to the patient. The present work introduces a low-cost, ventilator designed and built in accordance with the Emergence Use guidance provided by the US Food and Drug Administration (FDA) wherein an external gas supply feeds into the ventilator and time limited flow interruption guarantees tidal volume. The goal of this device is to allow a patient to be treated by a single ventilator platform, capable of supporting the various treatment paradigms during a potential COVID-19 related hospitalization. This is a unique aspect of this design as it attempts to become a one-device-one-visit solution to the problem. The device is designed as a single use ventilator that is sufficiently robust to treat a patient being mechanically ventilated. The overall design philosophy and its applicability in this new crisis-laden world view is first described, followed by both bench top and animal testing results used to confirm the precision, capability, safety and reliability of this low cost and novel approach to mechanical ventilation during the COVID-19 pandemic. The ventilator is shown to perform in a range of critical requirements listed in the FDA emergency regulations and can safely and effectively ventilate a porcine subject. As of August 2020, only 13 emergency ventilators have been authorized by the FDA, and this work represents the first to publish animal data using the ventilator. This proof-of-concept provides support for this cost-effective, readily mass-produced ventilator that can be used to support patients when the demand for ventilators outstrips supply in hospital settings worldwide. More details for this project can be found at https://ventilator.stanford.edu/

show abstract

A low-cost, highly functional, emergency use ventilator for the COVID-19 crisis

et al. 2022

Self Cite

View full text Add to dashboard Cite

Respiratory failure complicates most critically ill patients with COVID-19 and is characterized by heterogeneous pulmonary parenchymal involvement, profound hypoxemia and pulmonary vascular injury. The high incidence of COVID-19 related respiratory failure has exposed critical shortages in the supply of mechanical ventilators, and providers with the necessary skills to treat. Traditional mass-produced ventilators rely on an internal compressor and mixer to moderate and control the gas mixture delivered to a patient. However, the current emergency has energized the pursuit of alternative designs, enabling greater flexibility in supply chain, manufacturing, storage, and maintenance considerations. To achieve this, we hypothesized that using the medical gasses and flow interruption strategy would allow for a high performance, low cost, functional ventilator. A low-cost ventilator designed and built-in accordance with the Emergency Use guidance from the US Food and Drug Administration (FDA) is presented wherein pressurized medical grade gases enter the ventilator and time limited flow interruption determines the ventilator rate and tidal volume. This simple strategy obviates the need for many components needed in traditional ventilators, thereby dramatically shortening the time from storage to clinical deployment, increasing reliability, while still providing life-saving ventilatory support. The overall design philosophy and its applicability in this new crisis is described, followed by both bench top and animal testing results used to confirm the precision, safety and reliability of this low cost and novel approach to mechanical ventilation. The ventilator meets and exceeds the critical requirements included in the FDA emergency use guidelines. The ventilator has received emergency use authorization from the FDA.

show abstract

Low-Cost Differential Pressure Spirometry for Emergency Ventilator Tidal Volume Sensing

Cited by 3 publications

References 7 publications

Differential Pressure Spirometry for Mechanical Ventilation Using Dichotomic Search

Differential Pressure Spirometry for Mechanical Ventilation Using Dichotomic Search

A low-cost, rapidly scalable, emergency use ventilator for the COVID-19 crisis

A low-cost, highly functional, emergency use ventilator for the COVID-19 crisis

Contact Info

Product

Resources

About