Agreement Between Transcutaneous Monitoring and Arterial Blood Gases During COPD Exacerbation

Abstract

BACKGROUND: Transcutaneous measurements of CO 2 and O 2 (P tcCO 2 , P tcO 2 ) are noninvasive and allow for continuous monitoring in adults with exacerbation of COPD, but substantial accuracy issues may exist. We investigated agreement between results of arterial blood gas analysis and transcutaneous measurements of CO 2 and O 2 in patients with COPD. METHODS: Adult subjects were monitored after acute admission to a respiratory intermediate care unit or ICU due to exacerbation of COPD and with ongoing noninvasive ventilation or immediately following extubation. Monitored variables were continuous transcutaneous measurement and simultaneous routine arterial blood gas analysis. Agreement between measurements was assessed by calculating bias with 95% limits of agreement for single-point estimates of P tcCO 2 versus P aCO 2 and versus P aO 2 , and for changes in transcutaneous measurements between 2 time points (DP tcCO 2 and DP tcO 2 ). We considered limits of agreement within 6 7.5 mm Hg to be acceptable. RESULTS: A total of 57 transcutaneous measurements were made in 20 subjects for comparison with concurrent arterial blood gas analysis at 36 time points. The bias (limits of agreement) for P tcCO 2 and P tcO 2 was 2.5 mm Hg (-10.6 to 15.6 mm Hg) and 11.2 mm Hg (-28.2 to 50.6 mm Hg), respectively. The bias for DP tcCO 2 and DP tcO 2 was 2.3 mm Hg (-3.8 to 8.3 mm Hg) and -5.3 mm Hg (-37.5 to 27 mm Hg), respectively. CONCLUSIONS: P tcCO 2 and P tcO 2 did not accurately reflect results from arterial blood gas analyses in this study of mostly hypercapnic subjects. Agreement between changes in CO 2 during the monitoring period was acceptable, however, and transcutaneous monitoring may be used for continuous monitoring of P CO 2 in conjunction with arterial blood gas analysis for reference.

Utility of Initial Arterial Blood Gas in Neuromuscular versus Non-Neuromuscular Acute Respiratory Failure in Intensive Care Unit Patients

“…This finding is consistent with studies that have looked at COPD exacerbation cases and found an elevated mean of PaCO 2 of 59 mmHg [ 16 ]. Another recent study looked at COPD cases admitted to ICU with respiratory failure and found the mean PaCO 2 and PaO 2 to be 54 mmHg and 63 mmHg, respectively [ 17 ]. This is in contrast with another study that showed that most patients with COPD do not have elevated PaCO 2 , whereas PaO 2 levels vary between 60 and 80 mmHg [ 18 ].…”

Comparative analysis of hemoglobin, potassium, sodium, and glucose in arterial blood gas and venous blood of patients with COPD

“…Arterial blood gas (ABG) analysis is a commonly used tool for monitoring patients with COPD 7 . It provides clinicians with information on the patient's acid–base balance, partial pressures of oxygen and carbon dioxide, as well as levels of hemoglobin, potassium, sodium, and glucose simultaneously.…”