**Rodolfo Rocha Vieira Leocádio 1,2,\*, Alan Kardek Rêgo Segundo <sup>1</sup> and Cibelle Ferreira Louzada <sup>2</sup>**


**\*** Correspondence: rodolfo.leocadio@ufop.edu.br; Tel.: +55-31-98807-3747

Received: 30 September 2019; Accepted: 3 November 2019; Published: 21 November 2019

**Abstract:** This work proposes adapting an existing sensor and embedding it on mannequins used in cardiopulmonary resuscitation (CPR) training to accurately measure the amount of air supplied to the lungs during ventilation. Mathematical modeling, calibration, and validation of the sensor along with metrology, statistical inference, and spirometry techniques were used as a base for aquiring scientific knowledge of the system. The system directly measures the variable of interest (air volume) and refers to spirometric techniques in the elaboration of its model. This improves the realism of the dummies during the CPR training, because it estimates, in real-time, not only the volume of air entering in the lungs but also the Forced Vital Capacity (FVC), Forced Expiratory Volume (FEVt) and Medium Forced Expiratory Flow (FEF20–75%). The validation of the sensor achieved results that address the requirements for this application, that is, the error below 3.4% of full scale. During the spirometric tests, the system presented the measurement results of (305 ± 22, 450 ± 23, 603 ± 24, 751 <sup>±</sup> 26, 922 <sup>±</sup> 27, 1021 <sup>±</sup> 30, 1182 <sup>±</sup> 33, 1326 <sup>±</sup> 36, 1476 <sup>±</sup> 37, 1618 <sup>±</sup> 45 and 1786 <sup>±</sup> 56) <sup>×</sup> 10−<sup>6</sup> m3 for reference values of (300, 450, 600, 750, 900, 1050, 1200, 1350, 1500, 1650 and 1800) <sup>×</sup> 10−<sup>6</sup> m3, respectively. Therefore, considering the spirometry and pressure boundary conditions of the manikin lungs, the system achieves the objective of simulating valid spirometric data for debriefings, that is, there is an agreement between the measurement results when compared to the signal generated by a commercial spirometer (Koko brand). The main advantages that this work presents in relation to the sensors commonly used for this purpose are: (i) the reduced cost, which makes it possible, for the first time, to use a respiratory volume sensor in medical simulators or training dummies; (ii) the direct measurement of air entering the lung using a noninvasive method, which makes it possible to use spirometry parameters to characterize simulated human respiration during the CPR training; and (iii) the measurement of spirometric parameters (FVC, FEVt, and FEF20–75%), in real-time, during the CPR training, to achieve optimal ventilation performance. Therefore, the system developed in this work addresses the minimum requirements for the practice of ventilation in the CPR maneuvers and has great potential in several future applications.

**Keywords:** cardiopulmonary resuscitation; sensor; medical mannequins; spirometric techniques
