Transcutaneous CO₂ Monitoring in Respiratory Distress: Are Blood Gases Necessary?

Researchers prospectively compared 29 transcutaneous ear-clip arterial carbon dioxide (CO₂) measurements with simultaneous arterial blood gas measurements in 21 consecutive nonagitated adult patients with acute respiratory failure who presented to a single emergency department in France during a 1-month period. Three patients were in shock; all patients had a history of chronic cardiac or respiratory failure plus acute heart failure (6 patients), chronic obstructive pulmonary disease exacerbation (8), pneumonia (6), or pulmonary embolism (1).

At admission, mean PaCO₂ was 51.6 mm Hg (range, 23–84 mm Hg), and mean PaO₂ was 76 mm Hg (range, 32–215 mm Hg). Transcutaneous PaCO₂ measurements correlated well with arterial PaCO₂ measurements (mean d…