# Acute hYpErcapnic respiratory failure in The ICU: A multicenter prospective observational study - The YETI study

## TL;DR

This study found that about 5% of ICU patients have acute hypercapnic respiratory failure, often due to chronic lung diseases and infections, with specific risk factors for severe outcomes.

## Contribution

The study provides new large-scale epidemiological data on acute hypercapnic respiratory failure in ICU patients across multiple centers.

## Key findings

- AHcRF prevalence was 4.9% among ICU admissions and 12.5% among acute respiratory failure cases.
- Chronic obstructive pulmonary disease and infections were the main causes of AHcRF.
- Non-invasive ventilation was used in 81.3% of cases, but 35.9% required invasive ventilation.

## Abstract

Acute hypercapnic respiratory failure (AHcRF) is a common cause of intensive care unit (ICU) admission, particularly in patients with chronic respiratory diseases. However, large-scale epidemiological data on AHcRF prevalence, management, and outcomes in the ICU remain limited.

The YETI (Acute hYpErcapnic respiratory failure in The ICU) study was a prospective, multicenter, observational study conducted across 58 ICUs in France and Belgium between December 2021 and June 2022. Adult patients admitted with AHcRF (PaCO₂ > 45 mmHg and clinical signs of respiratory failure) were enrolled. The primary outcome was the prevalence of AHcRF among all ICU admissions. Secondary outcomes included etiologies, management strategies and factors associated with intubation and mortality.

Among 20,482 ICU admissions, 1,010 patients presented AHcRF, and 856 met inclusion criteria. The prevalence for AHcRF among all critically ill patients was 4.9% [95% CI: 4.6, 5.2], and among ICU patients admitted for acute respiratory failure, it was 12.5% [95 % CI: 11.8, 13.2]. Most patients had underlying obstructive lung diseases (Chronic Obstructive Pulmonary Disease: 56.3%; Obstructive Sleep Apnea Syndrome: 18.5%). Infection (52.2%) and cardiogenic pulmonary edema (15.4%) were the most frequent causes for respiratory failure. Non-invasive ventilation (NIV) was used in 81.3% of patients and 35.9% received invasive mechanical ventilation, mainly for coma or NIV failure. ICU mortality was 12.7%. Multivariable analysis identified lower pH, lower Glasgow Coma Scale, infectious etiology, and higher SOFA (Sequential Organ Failure Assessment) score as independent predictors of intubation. ICU mortality was associated with older age, lower body mass index, active cancer, and higher SOFA scores.

Ten percent of patients admitted to the ICU with respiratory failure present AHcRF, primarily driven by chronic obstructive diseases and infections. Despite widespread NIV use, one-third of patients were treated with invasive ventilation. Identifying risk factors for invasive mechanical ventilation and mortality may support earlier triage and personalized management strategies.