Acute respiratory failure (ARF) is a common and life-threatening medical emergency encountered in patients with various pulmonary diseases. It is characterized by the inability of the respiratory system to maintain adequate oxygenation and/or carbon dioxide elimination, leading to significant morbidity and mortality worldwide.[1] The global burden of ARF is increasing, particularly due to chronic respiratory illnesses such as chronic obstructive pulmonary disease (COPD), pneumonia, post-tuberculosis airway disease (TB-OAD), interstitial lung disease (ILD), and acute respiratory distress syndrome (ARDS).[2] Early and effective ventilatory support plays a crucial role in improving outcomes in such patients.

Non-invasive ventilation (NIV) has emerged as an important therapeutic modality to manage ARF by providing ventilatory assistance without the need for endotracheal intubation.[3] NIV reduces the work of breathing, improves gas exchange, prevents respiratory muscle fatigue, and decreases the need for invasive mechanical ventilation (IMV).[4] Its use has been associated with shorter hospital stays, reduced complications, and improved survival, particularly in COPD exacerbations and cardiogenic pulmonary edema.[5,6] In resource-limited settings, NIV offers additional advantages due to its relative ease of use, lower cost, and reduced requirement for intensive care resources.[7]

The effectiveness of NIV varies depending on the underlying etiology of ARF, patient selection, severity of illness, and timely initiation of therapy.[8] Studies have demonstrated that prompt NIV intervention leads to better outcomes in COPD patients, whereas its role in pneumonia, ILD, and ARDS remains less predictable and requires careful monitoring.[9,10] Early identification of factors predicting NIV success or failure is essential to avoid unnecessary delays in intubation, which may adversely affect patient prognosis.[11]

Despite the widespread use of NIV in tertiary hospitals, there is limited literature focusing on its effectiveness in rural tertiary healthcare settings in India, where patient characteristics, disease severity, and healthcare delivery models may differ from urban centers. Rural hospitals often face challenges such as delayed presentation, limited resources, and higher burden of infectious and obstructive lung diseases.[12] Evaluating the performance of NIV in such settings is important for guiding clinical practice, optimizing resource utilization, and improving patient outcomes.

Therefore, the present study was undertaken to assess the clinical outcomes of non-invasive ventilation in adult patients admitted with acute respiratory failure due to pulmonary diseases in a rural tertiary care hospital. The study analyzes demographic patterns, clinical characteristics, disease-specific outcomes, arterial blood gas (ABG) improvements, and factors associated with NIV success or failure. Findings from this study could contribute to evidence-based management protocols and enhance the quality of respiratory care in similar healthcare environments.

MATERIALS AND METHODS

Study Design

This study was a single-centre, observational, cross-sectional study that utilised both retrospective and prospective data collection methods. The study aimed to evaluate the clinical outcomes of non-invasive ventilation (NIV) in adult patients with acute respiratory failure (ARF) of pulmonary origin.

Study Setting

The study was conducted in the following units of the Department of Respiratory Medicine, Parul Institute of Medical Sciences & Research (PIMSR), Parul Sevashram Hospital, Vadodara, Gujarat:

• Respiratory Medicine Ward
• Intensive Care Unit (ICU)
• High Dependency Unit (HDU)

Study Duration

• Total Duration: 12 months
• Data Collection Period:
• Retrospective: From 1 January 2021
• Prospective: Until 31 March 2024
• Data Analysis: 1 month
• Manuscript/Thesis Preparation: 5 months

Study Population

The study population included adult patients aged ≥18 years admitted with acute respiratory failure (ARF) due to pulmonary diseases and managed with non-invasive ventilation (NIV) in the ward, HDU, or ICU.

Inclusion Criteria

• Adult patients (≥18 years) of either sex
• Diagnosed with acute respiratory failure secondary to pulmonary pathology
• Received NIV therapy during hospitalization

Exclusion Criteria

• Patients aged <18 years
• ARF due to non-pulmonary causes, including:
• Cardiac etiologies (e.g., cardiogenic pulmonary edema due to heart failure)
• Neurological disorders (e.g., neuromuscular diseases)
• Traumatic chest injury

Sample Size and Sampling Technique

A convenient sampling method was used.

A minimum of 100 patient records was required; a total of 110 patients meeting eligibility criteria over a 39-month period were included. Both retrospective and prospective records were analyzed.

Data Collection

Data were collected using a pre-designed, structured proforma. The following variables were recorded:

1. Demographic Variables

• Age, sex, body mass index (BMI)

2. Medical History

• Comorbidities
• Smoking status
• Previous hospital admissions

3. Clinical Parameters

• Vital signs
• Oxygen saturation (SpO₂)
• Arterial blood gas (ABG) values

4. Investigations

• Chest X-ray findings
• Hematological and biochemical test results

5. Clinical Diagnosis

• Type of underlying pulmonary disease (e.g., COPD, pneumonia, ILD)

6. NIV-Related Details

• Mode of NIV
• Initial and adjusted ventilatory settings
• Duration of NIV therapy

7. Clinical Outcomes

• Improvement on NIV
• Requirement of intubation
• In-hospital mortality

Statistical Analysis

Data were entered and analyzed using Microsoft Excel.

• Continuous variables were presented as mean ± standard deviation (SD).
• Categorical variables were expressed as frequencies and percentages.

Statistical Tests

• Chi-square test was applied to assess associations between categorical variables.
• Appropriate parametric or non-parametric tests (based on data distribution) were used for continuous variables.

Graphical representation (tables, bar charts, pie charts) was used where appropriate for better interpretation.

Ethical Considerations

Approval was obtained from the Institutional Ethics Committee (IEC).

Since the study involved anonymized retrospective and prospective clinical data without any intervention, a waiver of informed consent was granted.

• Confidentiality: Patient identity was protected through coding and restricted data access.
• Risk: None, as no additional procedures or interventions were performed.
• Benefit: Findings may enhance clinical understanding of NIV outcomes and guide evidence-based decision-making in ARF management.

RESULTS AND OBSERVATIONS;

Table; 1 Age and Gender Distribution and Their Correlation With Outcome

Table 2: Distribution of Respiratory diseases and it’s correlation with outcome

Table 3: Clinical features

Table 4: Correlation between Smoking and Outcome

Table; 5 mMRC Dyspnea Grade and Hemoglobin Levels With Outcome

Table: 6 Sputum AFB and Sputum Pyogenic Culture Findings

Figure; 1 Improvement in patient’s mean vitals parameters after NIV therapy

Table: 7 Mean ABGA Trends and Number of Patients Showing Improvement After NIV Therapy

Table: 8 Paired t-Test Analysis of Vital Signs and ABGA Parameters Before and After NIV Therapy

Table: 9 Duration of NIV Support and Overall Patient Outcomes

P value for NIV duration vs outcome = 0.138

Table; 10 Disease-Wise Improvement in pH and PaCO₂ at 2 Hours, 24 Hours, and End of NIV

Table:11 Disease-Wise Improvement in PaO₂ and HCO₃⁻ at 2 Hours, 24 Hours, and End of NIV

DISCUSSION

In this study, non-invasive ventilation (NIV) demonstrated a favorable overall success rate of 74.5%, highlighting its effectiveness in managing acute respiratory failure (ARF) due to various pulmonary diseases in a rural tertiary care setting. The findings support previous global evidence suggesting that NIV plays a crucial role in reducing the need for intubation, improving gas exchange, and lowering in-hospital mortality among appropriately selected patients with ARF. [1,2]

The age and gender distribution in our cohort showed no statistically significant association with NIV outcomes (p = 0.068 and 0.511, respectively), consistent with previous reports indicating that clinical severity and underlying etiology have greater prognostic value than demographic variables.[3] The majority of patients (54.5%) were aged 51–70 years, reflecting a higher burden of chronic respiratory illnesses in older adults.

Among diseases, COPD was the predominant diagnosis (41.7%), and these patients showed the highest improvement rates (86.9%). This aligns with multiple studies that identify COPD exacerbations as the most responsive indication for NIV, owing to its ability to reduce hypercapnia, respiratory muscle fatigue, and intubation rates.[4,5] In contrast, conditions like pneumonia, ILD, and pulmonary embolism showed comparatively lower improvement rates, echoing previous findings that NIV success in hypoxemic respiratory failure can be variable and depends on early recognition of deterioration.[6–8]

The clinical features observed—breathlessness (100%), fever (62.7%), and cough (35.4%)—are characteristic of ARF secondary to infectious and obstructive lung disease. Smoking, although prevalent (41.8%), did not show a significant correlation with NIV outcomes (p = 0.113). This may be due to the multifactorial nature of ARF severity, where acute physiologic derangement outweighs long-term risk factors.[9]

The mMRC dyspnea grading did not correlate significantly with NIV outcomes (p = 0.951), suggesting that subjective dyspnea severity is less predictive of NIV success compared to objective parameters such as ABG trends. Hemoglobin levels also showed no statistically meaningful association (p = 0.508), which is consistent with evidence that anemia alone is not a major determinant of NIV response.[10]

Arterial blood gas analysis revealed significant improvement in pH, PaCO₂, and PaO₂, particularly during the initial hours of NIV. Improvement in mean PaO₂ from 69.0 mmHg at admission to 90.8 mmHg after 2 hours reflects effective reversal of hypoxemia, which has been widely documented in patients receiving NIV for ARF.[11] Similarly, reductions in PaCO₂ and increases in pH underscore the beneficial effects of positive pressure ventilation on alveolar ventilation and respiratory muscle unloading.[12] These trends correspond with international data showing that early ABG improvements are strong predictors of NIV success.[13]

The paired t-test results further validate these physiological benefits, with statistically significant improvements in pulse rate, respiratory rate, blood pressure, pH, PaCO₂, PaO₂, and HCO₃⁻ (p < 0.05). Such changes are well established in literature as indicators of reduced respiratory distress and improved ventilation-perfusion matching.[14]

The duration of NIV therapy was not significantly associated with outcomes (p = 0.138), although most improved patients required NIV for 1–6 days, comparable to previously reported durations of 24–72 hours for stabilization in COPD and pneumonia cases.[15] Prolonged NIV beyond a week was uncommon but remained beneficial in select patients, particularly those with chronic CO₂ retention.

Disease-wise analysis showed that COPD, ILD, and post-TB OAD patients achieved better ABG improvements across time points. Conversely, diseases like ARDS and carcinoma lung had lower improvement rates, consistent with studies showing that NIV in ARDS or malignancy carries higher failure rates due to severe hypoxemia and poor lung compliance.[16,17]

The overall success rate of NIV in this study is comparable to Indian and international literature reporting success rates of 60–85% depending on case mix and severity.[18–20] Importantly, this study emphasizes that even in rural tertiary centers with limited resources, NIV remains a valuable modality for managing ARF, reducing the need for invasive ventilation, and improving survival outcomes when applied judiciously.

CONCLUSION

NIV proved to be an effective intervention for acute respiratory failure in this rural tertiary care setting, with a success rate of 74.5%. It significantly improved vital parameters and ABG values, especially in COPD, post-TB OAD, and ILD patients. Outcomes were largely determined by the underlying disease rather than age, gender, or smoking status. NIV was less effective in pneumonia, pulmonary embolism, ARDS, and malignancy. Overall, timely initiation and close monitoring enhance NIV success and reduce the need for invasive ventilation.

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