COPD exacerbations admitted to intensive care unit. Organization, mortality, and noninvasive or invasive mechanical ventilation strategies: are they sufficiently well known?

Dear editor

We read with interest the survival analysis of chronic obstructive pulmonary disease (COPD) patients who are admitted to critical care units with exacerbation, conducted in Saudi Arabia by Alaithan et al.¹ This study makes an important contribution on the real practice of intensive care units (ICUs). The authors, in the overall results, provided some great information similar in some aspects to previous epidemiologic surveys where a low level of consciousness on admission, need for endotracheal intubation (ETI), being a current smoker, cardiopulmonary arrest, tracheostomy, and development of acute renal failure are associated with higher ICU and hospital mortality. Although, study design showed some limitations with respect to interpretation predictors of mortality, there are aspects that differ compared to previous studies in this area that could be taken into account for clinical and practical implications.

First, there are no references regarding protocols of noninvasive mechanical (NIV) or invasive mechanical ventilation (IMV) implementation to ICU admissions, for example, where and how these mechanical ventilation options were performed at first line in the emergency departments. Additionally, there were not clearly defined criteria of applications, places or severity of exacerbation of COPD among participating ICUs. After endotracheal intubation (ETI) and IMV, the rate of successful weaning, prolonged mechanical ventilation, or tracheostomy practices are lacking. These are well known predictive factors associated with COPD in ICU and hospital mortality.^2,3 Interestingly, Alaithan et al did not consider COPD as a comorbidity associated with other indications of NIV or IMV.^4,5

Second, a relevant aspect that could influence hospital practices and COPD outcomes in this study¹ was that only 55% of COPD exacerbations received NIV as initial first line treatment and assumed that the remaining patients received oxygen therapy alone. These data may have health care implications for ICUs, because it could be refecting three potential scenarios: (1) delayed NIV applications, (2) staff training and skills, or (3) limited access to the NIV therapy (the availability of beds in ICU ward). These factors are related to COPD exacerbation and mortality and escape NIV international recommendations during exacerbations of COPD, an important epidemiological factor in this study.⁶

Third, the low rate of COPD hospital mortality (11%) and ICU mortality (6%) is lower than other studies and may be influenced by these aforementioned factors. However, there are other factors with recognized influence that were not analyzed, such as body mass index (BMI),⁷ lower health status, nutritional status, or nonrespiratory organ system dys-function.^2,3,8 Alaithan et al¹ considered that ICU mortality was associated with a longer duration of mechanical ventilation and lower Acute Physiology and Chronic Health Evaluation II (APACHE II)^2,3 score, but this is a controversial aspect by other epidemiological published studies.^2,3 Additionally, COPD readmissions,^7,8 existence of do not-ETI orders, and NIV palliative in severe exacerbation of COPD, were not taken into account.⁹

The study highlights the complexity of the epidemiological aspects that may affect attendance, prognosis, and mortality in different health systems.^8,9 Revealing the diversity of factors that affect NIV and IMV possibilities. Further studies are required to determine sensitive factors that could be modifiable that influence ICU admission criteria, prognosis, and mortality.