Purpose: Transcutaneous CO(2) monitors are widely used in neonatal ICUs. Until recently, these devices performed poorly in adults. Recent technical modifications have produced transcutaneous CO(2) monitors that have performed well in adults with chronic illnesses. We evaluated the accuracy of one of these devices, the TOSCA(®) 500, in adults admitted to an emergency department for acute respiratory failure.
Methods: We prospectively collected 29 pairs of simultaneous transcutaneous arterial CO(2) (PtcCO(2)) and arterial CO(2) (PaCO(2)) values in 21 consecutive adults with acute respiratory failure (acute heart failure, n = 6; COPD exacerbation, n = 8; acute pneumonia, n = 6; and pulmonary embolism, n = 1). Agreement between PaCO(2) and PtcCO(2) was evaluated using the Bland-Altman method.
Results: Mean arterial oxygen saturation was 90%, arterial oxygen tension ranged from 32 to 215 mmHg, and PaCO(2) ranged from 23 to 84 mmHg. The mean difference between PaCO(2) and PtcCO(2) was 0.1 mmHg, and the Bland-Altman limits of agreement (bias ± 1.96 SD) ranged from -6 to 6.2 mmHg. None of the patients experienced adverse effects from heating of the device clipped to the earlobe.
Conclusion: PtcCO(2) showed good agreement with PaCO(2) in adults with acute respiratory failure.