Transcutaneous Carbon Dioxide Monitoring During Acute Respiratory Distress Syndrome Due to Smoke Inhalation and Burns

Abstract

We evaluated the accuracy of continuous noninvasive transcutaneous carbon dioxide (tPCO2) monitoring utilizing the SenTec Digital Monitoring System in a model of ARDS due to smoke inhalation and burns.Subjectsanesthetized female Yorkshire pigs (47.4 ± 0.9 kg) received wood bark smoke inhalation injury and 40% total body surface area full thickness flame burn. A SenTec sensor heated to 43.5°C was used. Correlation of tPCO2 with arterial PaCO2 measured intermittently with i‐STAT blood gas analyzer.Resultsall animals developed ARDS at 23±2.08 hrs. Mean survival time was 51±14.9 hrs. A total of 88 paired measurements of PaCO2 and tPCO2 were performed. The mean overall bias between PaCO2 and tPCO2 under stable conditions (Bland‐Altman analysis (BAa)) was 0.75±5.34 mm Hg with overall correlation (R2 = 0.79, P<0.0001). Eighty‐nine percent of measurements were within the acceptable clinical range of agreement of ± 7.5mm Hg. This relationship deteriorated under hemodynamic instability with overall bias increasing to 17.3±18.5 mm Hg (BAa) and poor correlation (R2= 0.02, P=0.53) and only 33% of measurements were within the acceptable clinical range of agreement.ConclusionsTranscutaneous CO2 monitoring is a reliable surrogate for PaCO2 in the setting of severe lung injury and hemodynamic stability. Additional information must be considered during hemodynamic instability for accurate estimation of PaCO2.