Healthcare Technology Management (HTM) of mechanical ventilators by clinical engineers

An additive manufacturing fabricated a split Pitot tube transducer for mechanical ventilator analyzers

Introduction

Frequent calibration of ventilators and anesthesia machines might reduce the risk of death and of sequelae in patients under mechanical ventilation. However, ventilator analyzers might be difficult to purchase due to high cost or even in trade-restrictive scenarios, such as the COVID-19 pandemic. To alleviate this problem, the aim of this article is to present the design and characterization of a Pitot tube transducer fabricated with additive manufacturing (AM), to be used in ventilator analyzers.

Method

A split Pitot tube (SPT) transducer was designed using computer-aided design (CAD) and characterized using finite element method (FEM) simulations. Bernoulli’s equation was used to determine a transducer discharge coefficient. The sensor was fabricated with the acrylonitrile butadiene styrene (ABS) thermoplastic, with the fused deposition modeling after properly configuring the 3D printer.

Results

According to the simulated velocity profile, the transducer does not impose excessive resistance to the flow and the pressure profile revealed that the pressure is constant and stable inside the pressure lines. The characteristic curve of differential pressure (dP) versus flow is quadratic. For the minimal and maximal simulated flows 0.01 to 300 L/min, the corresponding dP values are 6.535·10⁻⁴ Pa and 13.178·10³ Pa.

Conclusion

The split Pitot tube transducer developed here has appropriate characteristics for measuring air flows from mechanical ventilators, and the delivered pressures can be read by commercial electronic sensors. The AM is viable for fabricating the transducer, and the printing time is considerably low compared to that necessary to order a similar part from a sales representative.