Early Detection of Acute Respiratory Failure Using an Intelligent Respiratory Monitoring System

Accuracy, Validation, and Usability of an Intelligent Respiratory Pattern Monitoring System in Patients at Risk of Acute Respiratory Failure

Introduction: The monitoring of respiratory patterns is crucial in the management of respiratory diseases, but in many cases, it still relies on subjective and visual assessment. The use of healthcare technologies based on artificial intelligence (AI) can, in these contexts, enhance clinical decision-making by providing a more objective and accurate analysis. Given the high prevalence of acute and chronic respiratory diseases, the implementation of a device capable of detecting variables such as flow, volume, and time becomes a priority for more effective diagnosis and therapeutic planning. Objective: Evaluate the accuracy, validity, and usability of an intelligent system for monitoring the respiratory pattern of patients at risk of acute respiratory failure. Methods: This is a prospective cohort study that will be conducted in the emergency departments of the Otávio de Freitas Hospital and Urgent Care Units (UPAs). The sample will consist of volunteers of both sexes, aged 18 years or older, breathing spontaneously, and suspected of having acute respiratory failure. Screening will be performed daily, where sociodemographic information, blood gas data, laboratory results, and additional information will be collected. When indicated, pulmonary function tests, respiratory muscle strength tests, and diaphragmatic ultrasound will be conducted. Respiratory pattern data will be collected using the Respiratory Diagnostic Assistant. Statistical analysis will be performed according to data modeling and treatment, adopting significant differences with p < 0.05. Expected Results: It is expected that the results of this study will provide quantitative data on the respiratory pattern of volunteers suspected of having acute respiratory failure. This information will be integrated into a database with the aim of enhancing the device's ability to detect changes in respiratory patterns, as well as contributing to the development of artificial intelligence capable of accurately and efficiently identifying these changes.

Monitoring respiratory patterns is essential in the management of respiratory diseases, yet it often still relies on subjective and visual assessments. Health technologies based on artificial intelligence (AI) can enhance clinical decision-making by providing more objective and accurate analyses. Given the high prevalence of acute and chronic respiratory diseases, implementing devices capable of detecting variables such as flow, volume, and time has become a priority for enabling more effective diagnosis and therapeutic planning. This study aims to evaluate the accuracy, validity, and usability of an intelligent system for monitoring respiratory patterns in patients at risk of acute respiratory failure.

This is a prospective cohort study to be conducted in the emergency departments of Hospital Otávio de Freitas and Urgent Care Units (UPAs), involving volunteers of both sexes, aged 18 years or older, breathing spontaneously, and under suspicion of acute respiratory failure. Daily screening will be performed, collecting sociodemographic, blood gas, laboratory, and additional clinical data. When indicated, pulmonary function tests, respiratory muscle strength assessments, and diaphragmatic ultrasonography will be performed. Respiratory patterns will be recorded using the Respiratory Diagnostic Assistant (RDA), with data collected directly at the patient's bedside, preferably in a seated position or, if not feasible, in the supine position with the head of the bed elevated to 30°. The device will be used with appropriate protective filters and a face mask properly fitted to the patient, preceded by a clinical evaluation that includes peripheral oxygen saturation, respiratory rate, and signs of respiratory distress. The protocol comprises three minutes of spontaneous basal breathing to record time, volume, and flow variables.

Simultaneously with the RDA assessment, respiratory parameters will also be measured using conventional methods-manual or multiparameter monitor respiratory rate, arterial blood gas analysis (when clinically indicated), pulse oximetry, and spirometry-serving as reference standards for diagnostic accuracy analysis. The collected data will be analyzed using correlation coefficients, agreement tests, and ROC curves to assess the sensitivity, specificity, and overall performance of the RDA algorithm. In addition to accuracy, clinical usability of the device will be evaluated using the System Usability Scale (SUS) questionnaire, assessing interface clarity, ease of mask fitting, examination duration, data interpretation, and clinical applicability. The mean SUS score will be used as an indicator of acceptance, with values ≥68 considered satisfactory.

All clinical and technical data will be securely stored on an encrypted server with access restricted to the research team, in compliance with the Declaration of Helsinki, Brazilian regulations, and the General Data Protection Law (LGPD). Participation will be voluntary, requiring the signing of an informed consent form (ICF) by patients or, when applicable, their legal representatives. Data will be stored in Microsoft Excel 2016 (Microsoft®, USA) and analyzed using SPSS Statistics v.22.0. Descriptive variables will be presented as means and standard deviations or as medians and interquartile ranges, depending on their distribution, assessed using the Kolmogorov-Smirnov test.

The analysis will be guided by three main hypotheses: (1) Accuracy - to assess whether the intelligent monitoring system provides superior performance compared to conventional methods in detecting respiratory pattern alterations, using performance metrics such as accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the ROC curve (AUC), with comparisons made using McNemar's test for paired binary data and AUC comparisons using the z-test; (2) Validation - to verify the system's precision and reliability using the Intraclass Correlation Coefficient (ICC) and Bland-Altman analysis, as well as Cohen's Kappa index for categorical variables, with ICC values above 0.75 indicating satisfactory validation; (3) Usability - to assess system acceptance based on SUS scores, complemented by analysis of average training time and operational error rates, using the Student's t-test or Mann-Whitney test depending on data distribution.

The study is expected to generate robust quantitative data on the respiratory patterns of patients with suspected acute respiratory failure, contributing to the refinement of the device, the development of more accurate AI algorithms, and its safe and effective integration into clinical practice.

Inclusion Criteria:

• Volunteers and patients of both sexes
• Age greater than or equal to 18 years
• Spontaneous breathing
• Patients awaiting care in emergency departments, urgent care units, and emergency services
• Presence of complaints associated with respiratory difficulty
• Patients at risk of acute respiratory failure
• With or without supplemental oxygen therapy
• Ability to remain without oxygen therapy for a minimum period of three minutes

Exclusion Criteria:

• Psychomotor agitation
• Anxiety validated through qualitative assessment
• Poor mask fit and/or presence of air leaks
• Facial fracture or trauma
• Refusal to participate in the study or sign the informed consent form
• Contraindications to performing manovacuometry and spirometry, when appropriate, according to the recommendations of the American Thoracic Society and European Respiratory Society (Graham et al., 2019)