High mortality, health care use for patients with hypercapnic respiratory failure

Hospitalized patients with compensated hypercapnic respiratory failure have high rates of mortality and health care utilization, with higher elevated carbon dioxide partial pressure associated with worse survival, researchers reported.

“Patients with underlying COPD, obesity hypoventilation syndrome, neuromuscular disease or thoracic cage abnormalities may develop compensated hypercapnic respiratory failure without acidosis,” Matthew W. Wilson, MD, physician in the division of pulmonary and critical care at the University of Michigan, and colleagues wrote in Annals of the American Thoracic Society. “Acute hypercapnic respiratory failure is associated with worse outcomes in a variety of clinical settings, such as increased mortality in patients with COPD, the development of acute respiratory distress syndrome and requiring mechanical ventilation in the ICU.”

Researchers identified 491 patients (mean age, 60.5 years; 57.4% men) hospitalized at the University of Michigan with compensated hypercapnia (carbon dioxide partial pressure 50 mm Hg and pH of 7.35 to 7.45 on arterial blood gas) from January to December 2018. Using demographic and clinical data, researchers determined survival probabilities for subgroups of patients with carbon dioxide partial pressure 50 mm Hg to 54.9 mm Hg (n = 221), 55 mm Hg to 64.9 mm Hg (n = 171) and 65 mm Hg or more (n = 99).

The mean pH was 7.38 and mean carbon dioxide partial pressure was 58.8 mm Hg.

During the study period, 1,030 hospitalizations were recorded, with 44.4% of the patients requiring two or more hospital admissions.

Researchers reported a median of 21 cumulative hospital days and a median of 7 ICU days. Forty-four percent of patients died during a median follow-up of 592 days.

Each 5 mm Hg increase in carbon dioxide partial pressure was associated with higher risk for all-cause mortality (HR = 1.09; 95% CI, 1.03-1.16; P = .004) in a univariate analysis. This association remained after adjusting for age, sex, BMI and Charlson comorbidity index (HR = 1.09; 95% CI, 1.02-1.16; P = .009).

Researchers reported a significant interaction between carbon dioxide partial pressure, BMI and patient mortality (P = .01).

“Inpatient clinicians should identify these patients as high risk despite their metabolic compensation,” the researchers wrote. “Health care providers may consider referral to pulmonology to explore the possibility of initiating noninvasive ventilator therapy.”