Abstract
Background: Chronic hypercapnic respiratory failure is associated with high mortality. While prior work has demonstrated a mortality improvement with high intensity non-invasive ventilation in chronic obstructive pulmonary disease, it is unclear whether a partial pressure carbon dioxide (PCO2) reduction strategy is associated with improved outcomes in other populations of chronic hypercapnia.
Methods: The objective of this study was to investigate the association between PCO2 reduction (using transcutaneous partial pressure of carbon dioxide as an estimate for arterial PCO2) and survival in a broad population of individuals treated with NIV for chronic hypercapnia. We hypothesized that reductions in PCO2, would be associated with improved survival. Therefore, we performed a cohort study of all subjects evaluated from February 2012 to January 2021 for NIV initiation/optimization due to chronic hypercapnia at a home ventilation clinic in an academic center. We used multivariable Cox proportional hazard models with time-varying coefficients and PCO2 as a time-varying covariate to test the association between PCO2 and all-cause mortality adjusting for known cofounders.
Results: The mean age of 337 subjects was 57 ± 16 years; 37% female and 85% white. In univariate analysis, survival probability increased with reductions in PCO2 to <50 mm Hg after 90 days, and these remained significant after adjusting for age, sex, race, body mass index, diagnosis, Charlson comorbidity index, and baseline PCO2. In the multivariable analysis, patients who had a < 50 mm Hg had a reduced mortality risk of 94% between 90–179 days (HR=0.06; 95% CI: 0.01 – 0.50), 69% between 180 – 364 days (HR=0.31; 95% CI: 0.12 – 0.79), and 73% for 365 -730 days (HR = 0.27; 95% CI: 0.13 – 0.56).
Conclusion: Reduction in PCO2 from baseline for subjects with chronic hypercapnia on NIV is associated with improved survival. Management strategies should target the greatest attainable reductions in PCO2.
- Noninvasive Ventilation
- Hypercapnia
- Respiratory Insufficiency
- Mortality
- Amyotrophic Lateral Sclerosis
- Neuromuscular Diseases
- Chronic Obstructive Pulmonary Disease
Footnotes
- Corresponding Author:
Philip J. Choi, Division of Pulmonary and Critical Care Medicine - University of Michigan, 3916 Taubman Center, 1500 E. Medical Center Dr, Ann Arbor, MI 48109, USA. Email: pchoi{at}med.umich.edu.
- Received December 15, 2022.
- Accepted May 1, 2023.
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