Assessment of respiratory mechanics extends from basic research and animal modeling to clinical applications in humans. However, to employ the applications in human models, it is desirable and sometimes mandatory to study non-human animals first. To acquire further precise and controlled signals and parameters, the animals studied must be further distant from their spontaneous ventilation. The majority of respiratory mechanics studies use positive pressure ventilation to model the respiratory system. In this scenario, a few drug categories become relevant: anesthetics, muscle blockers, bronchoconstrictors, and bronchodilators. Hence, the main objective of this study is to briefly review and discuss each drug category, and the impact of a drug on the assessment of respiratory mechanics. Before and during the positive pressure ventilation, the experimental animal must be appropriately sedated and anesthetized. The sedation will lower the pain and distress of the studied animal and the plane of anesthesia will prevent the pain. With those drugs, a more controlled procedure is carried out; further, because many anesthetics depress the respiratory system activity, a minimum interference of the animal’s respiration efforts are achieved. The latter phenomenon is related to muscle blockers, which aim to minimize respiratory artifacts that may interfere with forced oscillation techniques. Generally, the respiratory mechanics are studied under appropriate anesthesia and muscle blockage. The application of bronchoconstrictors is prevalent in respiratory mechanics studies. To verify the differences among studied groups, it is often necessary to challenge the respiratory system, for example, by pharmacologically inducing bronchoconstriction. However, the selected bronchoconstrictor, doses, and administration can affect the evaluation of respiratory mechanics. Although not prevalent, studies have applied bronchodilators to return (airway resistance) to the basal state after bronchoconstriction. The drug categories can influence the mathematical modeling of the respiratory system, systemic conditions, and respiratory mechanics outcomes.

This technical report presents the quality assessment process for the emergency corrective maintenance of critical care ventilators in a node, IPT-POLI, of a voluntary network that is part of the initiative +Maintenance of Ventilators, led by the National Service of Industrial Training (SENAI) and its Integrated Manufacturing and Technology Center (CIMATEC) to perform maintenance on unused mechanical ventilators in the context of the COVID-19 pandemic in Brazil. A procedure was established for the quality assessment of equipment subjected to corrective emergency maintenance, covering the essential aspects of the three primary standards (ABNT NBR IEC 60601-1: 2010+A1:2016, ABNT NBR ISO IEC 62353: 2019, and ABNT NBR ISO 80601-2-12:2014) for performance and safety assessment. A set of nine critical care ventilators was evaluated considering the following parameters: leakage current, protective ground resistance, control accuracy, delivered oxygen test, and alarms. The evaluated ventilators underwent corrective emergency maintenance before performance and safety assessments. In the electrical safety tests, all equipment presented values prescribed for the standard. However, the assessment of ventilator parameters revealed that their performance was below the standard. Finally, quality assessment reports were sent to the clinical engineering departments at hospitals. Thus, it can be concluded that criteria selection for the quality assessment in critical care ventilators is crucial and of great significance for future pandemic scenarios, such as the situation experienced during the COVID-19 pandemic.

Continuous mandatory ventilation with pressure control (CMV-PC) was one of the first ventilation-modes to be introduced, and continues to be one of the most widespread ventilation-modes to manage patients with acute respiratory failure. In attempt to provide information regarding ventilation-modes performance to help clinicians, researchers have been evaluating ventilation-modes parameters over the years. Previous literature reported an operational variability across different models. These studies, however, have not had the same test scenarios, and they have mostly used top-line lung ventilators. Even more, the criteria used to measure the evaluated parameters were not fully detailed, and its calculation was based on commercial instruments. Thus, this research aims to compare different airway-pressure waveform patterns from different lung ventilators in CMV-PC, detailing the criteria used to measure the parameters and using lung ventilator models that are available on the Brazilian market. In this study, 12 lung ventilators were evaluated. For the experiments, flow and pressure signals were acquired at 100Hz. An experimental setup was chosen from ABNT NBR ISO IEC 80601-2-12: 2014. It comprises four test scenarios with different combinations of compliance and resistance: 1 (50 mL/cmH 2 O-5 cmH 2 O/L/s), 2 (50 mL/cmH 2 O-20 cmH 2 O/L/s), 3 (20 mL/cmH 2 O-5 cmH 2 O/L/s), and 4 (20 mL/cmH 2 O-20 cmH 2 O/L/s).Evaluated parameters were inspiratory pressure, positive end-expiratory pressure (P EEP ), inspiratory time (T I ), time interval to reach 90% of the set pressure (T 90 ), peak inspiratory pressure, peak inspiratory flow, inspiratory area (AI), expiratory area (AE), percentage of inspiratory area (I%) and percentage of expiratory area (E%). To address statistical differences, we conducted the Kruskal-Wallis test, and the Dunn's test for multiple comparisons. In addition, a standard-based assessment was performed for inspiratory pressure, P EEP and T I . Even though the lung ventilators had the same configurations for all the test scenarios and obeyed the same standard, statistical differences were found for all the evaluated parameters, and between some lung ventilators (P < 0.05). Surprisingly, there were 5 lung ventilators that could not reach 90% of the set pressure. Further, an overshooting of 2.95 cmH 2 O in test scenario 3 was measured. Relating to the standard-based assessment, inspiratory pressure test's results showed that 4, 8, 2 and 3 lung ventilators failed in test scenarios 1, 2, 3, and 4, respectively. For PEEP test's results, we had 3 lung ventilators that were reproved in test scenarios 1, 2, and 4; and 2 lung ventilators reproved in test scenario 3. With respect of T I , all the lung ventilators passed the test. This study evidenced that airway-pressure waveforms in CMV-PC varied among lung ventilators, mainly in T 90 (or understandably in rise time), and inspiratory pressure. Disparities were more noticeable in test scenario 3 that has higher values of compliance and resistance. An intriguing f...

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