Epidemiology of Non- Invasive Mechanical Ventilation in Argentina: a Multicenter Observational Study

Background and Rationale Non-invasive mechanical ventilation (NIMV) has become a crucial treatment in managing acute respiratory failure, preventing the need for endotracheal intubation and its associated complications. Numerous studies have demonstrated that timely and appropriate NIMV use reduces mortality, decreases the incidence of ventilator-associated pneumonia, and minimizes hospital length of stay. However, the epidemiology of NIMV use in Argentina remains largely undocumented, particularly regarding regional disparities in access, implementation, and patient outcomes.

This multicenter observational study aims to fill this knowledge gap by analyzing NIMV utilization in intensive care units (ICUs) across Argentina. The study will evaluate patient characteristics, clinical outcomes, and factors influencing NIMV success or failure. Additionally, it will assess the impact of healthcare staff training and the differences between public and private healthcare settings.

Study Objectives Primary Objective

• Analyze the survival rates of ICU patients receiving NIMV.

Secondary Objectives

• Identify factors associated with NIMV success or failure, including the need for intubation.
• Describe demographic and clinical characteristics of patients requiring NIMV.
• Compare mortality rates between successful and failed NIMV cases.
• Evaluate regional disparities in resource availability and NIMV usage.
• Analyze the impact of staff training levels on patient outcomes.
• Compare NIMV practices between public and private hospitals.
• Establish a national database to facilitate ongoing assessment of NIMV in Argentina.

Study Design This is a prospective, multicenter, observational, and analytical study that will collect data from ICUs in both public and private hospitals across different regions of Argentina. The study will be conducted over seven months to capture seasonal variations in respiratory diseases. All enrolled patients will be followed until discharge or death.

Population and Setting The study will include adult patients (≥18 years old) admitted to ICUs and requiring NIMV for acute respiratory failure or as part of weaning from invasive mechanical ventilation (IMV). Participating hospitals must have the capacity to provide NIMV and record detailed patient data.

Eligibility Criteria

Inclusion Criteria:

• Patients ≥18 years old requiring NIMV in ICU for acute respiratory failure (hypoxemic, hypercapnic, or mixed) or as part of IMV weaning.
• Patients receiving palliative NIMV or as part of end-of-life care.
• Patients requiring increased duration or level of NIMV support due to worsening condition.
• Signed informed consent from the patient or a legal representative.

Exclusion Criteria:

• Patients using home NIMV for chronic respiratory conditions (e.g., COPD, neuromuscular diseases, obesity hypoventilation syndrome) without acute respiratory deterioration.
• Patients without acute respiratory distress at ICU admission.

Data Collection and Variables Data Management System

• Data will be collected using an electronic form in RedCap® with restricted access.
• Each participating ICU will have a designated site coordinator responsible for data collection and entry.
• To ensure data accuracy, a monitoring committee will review a random 5% sample of enrolled patients.

Key Variables Baseline Data

• Demographics: Age, sex, weight, height.
• ICU admission data: Date of hospital and ICU admission.
• Charlson Comorbidity Index and APACHE II score at ICU admission.
• Previous NIMV or oxygen therapy use (home or pre-ICU).

NIMV Implementation

• Date of NIMV initiation in ICU.
• Initial arterial blood gas (ABG) values: pH, PaCO₂, PaO₂, SaO₂, FiO₂.
• Primary reason for NIMV: COPD exacerbation, asthma, pneumonia, ARDS, post-operative respiratory failure, cardiogenic pulmonary edema, neuromuscular disease, etc.
• Ventilator settings: Mode (e.g., PSV, PCV), inspiratory pressure, PEEP, FiO₂, respiratory rate, tidal volume.
• Interface used: Helmet, oronasal mask, nasal mask, mouthpiece.
• Humidification use (active/passive).
• Adjunct therapies: Sedation, analgesia, high-flow nasal oxygen (HFNO).

Monitoring and Outcomes

• Daily ABG values and ventilator settings during NIMV use.
• Signs of respiratory distress: Tachypnea, accessory muscle use, paradoxical breathing.
• Complications: Facial pressure ulcers, barotrauma, pneumonia, gastric distension.
• Failure criteria: Need for intubation or death during NIMV.
• Length of NIMV use and ICU/hospital stay duration.
• Mortality at day 28 and at hospital discharge.
• Final disposition: Discharge to home, rehabilitation center, or another hospital unit.

Statistical Analysis

• Descriptive statistics:
• Continuous variables: Mean ± SD or median (IQR).
• Categorical variables: Frequency and percentages.
• Comparative analysis:
• Student's t-test or Mann-Whitney U test for continuous variables.
• Chi-square test or Fisher's exact test for categorical variables.
• Multivariate analysis:
• Logistic regression to identify predictors of NIMV failure.
• Kaplan-Meier survival analysis and Cox proportional hazards model to assess survival outcomes.
• Missing data handling: Patients with >10% missing key variables will be excluded from the final analysis.
• Software: All statistical analyses will be performed using R 4.3.3, with ggplot2 for visualizations and Survival package for survival analysis.

Bias Control and Quality Assurance

• Selection bias: Consecutive patient recruitment to minimize inclusion bias.
• Information bias: Standardized electronic data collection with training for investigators.
• Investigator bias: Use of predefined diagnostic criteria and cut-off values.

Ethical Considerations

• The study will comply with international research ethics standards (Helsinki Declaration, ICH-GCP).
• Data will be anonymized and securely stored, following Argentina's Data Protection Law (25.326/00).
• Ethical approval will be obtained from the Ethics Committee of the British Hospital of Buenos Aires and participating institutions.

Study Feasibility

• The study will be coordinated by the British Hospital of Buenos Aires with support from the Argentine Society of Intensive Care Medicine (SATI).
• No external funding; the study is supported by SATI.
• Participating centers will be invited via SATI networks and social media, with a structured training program to ensure compliance with data collection protocols.

Conclusion This study will provide essential insights into NIMV epidemiology in Argentina, helping to optimize its implementation and improve ICU care nationwide. By identifying key predictors of success or failure, the study will contribute to evidence-based clinical practice and inform national health policies regarding ventilatory support strategies.