- Kelly and Klim have looked at the correlation of pH and PCO2 between arterial and venous samples in a group of 53 patients on NIV with 89 sample pairs being evaluated.
- These were predominantly in patients with COPD (43%) and APO (40%)
- The mean difference in pH was 0.04 (95% CI -0.02 - 0.11)
- The mean difference in PCO2 was -8.02 mmHg (95% CI -22.63 - 6.58)
- They concluded that there was good correlation with the pH, but poor correlation with the PCO2.
Take Home Message - in patients with respiratory distress from COPD and APO on NIV, use an arterial sample to accurately ascertain respiratory status (PCO2).
Kelly AM, Klim S. Agreement between arterial and venous pH and in patients undergoing non-invasive ventilation in the emergency department. EMA 2013 (Early Online - DOI: 10.1111/1742-6723.12066)