CHALLENGES OF RESPIRATORY THERAPY IN PATIENTS WITH SEVERE AND CRITICAL COVID-19 IN RESOURCE-LIMITED COUNTRIES

Introduction. The COVID-19 pandemic has underscored the critical importance of effective oxygen therapy in managing severe and critical cases of the disease. Hypoxemic respiratory failure remains a hallmark of progressive COVID-19, often necessitating escalating oxygen support—from conventional nasal cannulas to high-flow systems, non-invasive ventilation, and invasive mechanical ventilation. Despite advances in treatment protocols, the optimal strategies for oxygen delivery, timing of escalation, and avoidance of complications such as oxygen toxicity continue to challenge clinicians worldwide. The aim. To evaluate the strategies and results of respiratory support in patients with severe and critical course of COVID-19. Materials and methods. This study examined medical records from 1,311 COVID-19 patients admitted to Kyiv City Clinical Hospital No. 17 between September 2020 and December 2021. Of these, 252 cases (19.2 %) were classified as severe or critical according to established disease severity criteria. Following application of predetermined exclusion parameters, the final study cohort consisted of 221 eligible patients (representing 87.7 % of qualifying cases), with a near-equal gender distribution (113 females [51.1 %] and 108 males [48.9 %]). All patients received oxygen therapy during hospitalization and underwent pre-oxygen therapy evaluation upon ICU admission, with baseline parameters. Respiratory status included respiratory rate and SpO2 , gas exchange was assessed via PaO2 /FiO2 ratio. Disease severity was evaluated using SOFA score and SMART-COP. Clinical/demographic data from medical reports included age, sex, BMI, Charlson Comorbidity Index (CCI), ventilation parameters (PIP, PaO2 /FiO2 , IMV duration), and outcomes (mortality rate, pre-intubation oxygen therapy duration). Results. Among 221 severe/critical COVID-19 patients, 191 (86.4 %) initially received nasal cannula oxygen/ face masks, but 150 (68.2 %) required escalation due to worsening hypoxemia. Non-invasive ventilation (NIV) was attempted in these patients, succeeding in 45.6 %—more likely in younger (58.7 vs. 61.1 yrs), less obese (BMI 29.8 vs. 31.5), and lower comorbidity (CCI 3.2 vs. 3.93) cases. Mechanical ventilation (MV) was needed in 71 (32.1 %) after NIV failure and 30 (13.6 %) admitted with multiorgan failure and critical course. MV patients were predominantly male, with mean age 61.1 ± 14.3 yrs, BMI 31.5 ± 5.2, and high comorbidity (CCI 3.93 ± 3.32). Severe respiratory failure before MV (PaO2 /FiO2 136.3 ± 91.1, PIP 25.9 ± 6.6 cm H2O) reflecting extreme disease severity. Mean IMV duration was 9.8 ± 11.3 days, with 93.1 % mortality. Conclusion. This study highlights the critical role of respiratory therapy strategies in managing severe and critical COVID-19, demonstrating that clinical outcomes are closely tied to both the timing and modality of respiratory support. Our findings reveal that while non-invasive ventilation (NIV) and nasal oxygen/ face masks can effectively prevent intubation in carefully selected patients. But delayed escalation to invasive mechanical ventilation (IMV) in non-responders is associated with significantly high mortality (93.1 %). The high fatality rate among intubated patients underscores the importance of early recognition of treatment failure and timely intervention, particularly in high-risk populations with comorbidities, advanced age, or severe hypoxemia (PaO2 /FiO2 <150).