Severity of acidosis affects long-term survival in COPD patients with hypoxemia after intensive care unit discharge.

Background: Patients admitted to the intensive care unit (ICU) with acute respiratory failure (ARF) due to COPD have high mortality and morbidity. Acidosis has several harmful effects on hemodynamics and metabolism, and the current knowledge regarding the relationship between respiratory acidosis severity on the short- and long-term survival of COPD patients is limited. We hypothesized that COPD patients with severe acidosis would have a poorer short- and long-term prognosis compared with COPD patients with mild-to-moderate acidosis. Patients and methods: This retrospective observational cohort study was conducted in a level III respiratory ICU of a tertiary teaching hospital for chest diseases between December 1, 2013, and December 30, 2014. Subject characteristics, comorbidities, ICU parameters, duration of mechanical ventilation, length of ICU stay, ICU mortality, use of domiciliary noninvasive mechanical ventilation (NIMV) and long-term oxygen therapy (LTOT), and short- and long-term mortality were recorded. Patients were grouped according to their arterial blood gas (ABG) values during ICU admission: severe acidotic (pH≤7.20) and mild-to-moderate acidotic (pH 7.21-7.35). These groups were compared with the recorded data. The mortality predictors were analyzed by logistic regression test in the ICU and the Cox regression test for long-term mortality predictors. Results: During the study period, a total of 312 COPD patients admitted to the ICU with ARF, 69 (72.5% male) in the severe acidosis group and 243 (79% male) in the mild-to-moderate acidosis group, were enrolled. Group demographics, comorbidities, duration of mechanical ventilation, and length of ICU stay were similar in the two groups. The severe acidosis group had a significantly higher rate of NIMV failure (60.7% vs 40%) in the ICU. Mild-to-moderate acidotic COPD patients using LTOT had longer survival after ICU discharge than those without LTOT. On the other hand, severely acidotic COPD patients without LTOT showed shorter survival than those with LTOT. Kaplan-Meier cumulative survival analysis showed that the 28-day and 1-, 2-, and 3-year mortality rates were 12.2%, 36.2%, 52.6%, 63.3%, respectively (p=0.09). The Cox regression analyses showed that older age, PaO2/FiO2 <300 mmHg, and body mass index ≤20 kg/m2 was associated with mortality of all patients after 3 years. Conclusion: Severely acidotic COPD patients had a poorer short- and long-term prognosis compared with mild-to-moderate acidotic COPD patients if acute and chronic hypoxemia was predominant.

Eosinophilic and non-eosinophilic COPD patients with chronic respiratory failure: neutrophil-to-lymphocyte ratio as an exacerbation marker.

AIM: Increased dyspnea, sputum volume, and purulence are subjective symptoms in COPD patients. To diagnose COPD exacerbations with chronic respiratory failure (CRF) and to assess the requirement for antibiotic treatment, physicians require more objective criteria. We aimed to investigate whether neutrophil-to-lymphocyte ratio (NLR) can be used as an infectious exacerbation marker in COPD patients with CRF. PATIENTS AND METHODS: This retrospective cross-sectional study was performed in the intensive care outpatient clinic of a tertiary training hospital between 2014 and 2015. Patients admitted with CRF due to COPD and who had complete blood count (CBC) results were enrolled. CBC results and C-reactive protein (CRP) levels were obtained from the hospital online database. The "modified exacerbation model (MEM)" was defined as follows: exacerbation A, leukocytes ≥12,000/mm3, CRP >10 mg/dL; exacerbation B, leukocytes ≥10,000/mm3, CRP >10 mg/dL; exacerbation C, leukocytes ≥10,000/mm3, CRP >8 mg/dL; exacerbation D, leukocytes ≥10,000/mm3, CRP >5 mg/dL. The cutoff value of NLR was defined for each model. Patients were split into two groups based on the NLR cutoff value according to the "NLR exacerbation model" and further subgrouped according to peripheral eosinophil percentage (eosinophils ≥2% and <2%) and compared with the MEM. RESULTS: A total of 1,066 COPD patients (430 females, 40.3%), with a mean age of 66±13 years, were included. A NLR cutoff value of 3.54 (NLR ≥3.54, n=366, 34%) showed the highest sensitivity and specificity for model A (78%, 69%), model B (63%, 71%), model C (61%, 72%), and model D (58%, 72%). Peripheral eosinophilia (PE ≥2%) was present in 48 patients (4.5%). The ratio of patients with PE <2% in the NLR ≥3.54 group was significantly higher in the MEM (P<0.001). CONCLUSION: The NLR presents an attractive option as an exacerbation marker in COPD patients with CRF due to its simplicity and cost-effectiveness. In COPD patients with CRF, where the NLR is ≥3.54, PE levels are <2%, and subjective symptoms are present, antibiotic treatment should be considered.