Transcutaneous carbon dioxide monitoring could reduce physical contact with COVID-19 patients

Abstract

Background: Transcutaneous carbon di-oxide (TcCO2) monitoring can be valuable to allow non-invasive monitoring of plasma carbon dioxide (PaCO2) levels in patients with acute respiratory failure including those with novel coronavirus disease 2019 (COVID-19). Methods: A pilot retrospective chart review was performed on critically-ill, adult patients admitted to the medical intensive care unit to assess correlation between TcCO2 and PaCO2 values. Obtained demographics, diagnoses, acute physiology, and chronic health evaluation II score (APACHE II), and Charlson co-morbidity index. TcCO2 values compared with corresponding blood gas PaCO2 values - including patients requiring inotropic agents. Microsoft Excel 2016 and IBM SPSS Statistics for Windows, version 26 (IBM Corp., Armonk, N.Y., USA) used for statistical analysis. Results: Cohort consisted of 53 patients with acute respiratory failure from a variety of documented overlapping diagnoses. Thirty-one (58.4%) needed invasive mechanical ventilation, 20 (37.7%) required non-invasive ventilation with impending need for intubation and 2 patients (3.8%) who did not require oxygen delivery beyond high flow nasal cannula. Forty patients provided 121 instances of paired measurements of TcCO2 and PaCO2 where values were strongly correlated, r(121)=.90, p[less than]0.001, including 54 instances where patients received one or more inotrope infusions at time of measurement. In the paired measurement cohort, the sum of instances per overlapping diagnosis accounted for 47[38.8%] COVID-19, 20[16.5%] interstitial lung disease, 69[57%] pneumonia, 74[61.2%] septic shock, 23[19%] acute exacerbation of chronic obstructive lung disease, 8[6.6%] pulmonary embolism, 13[10.7%] aspiration pneumonia, 7[5.8%] severe pulmonary hypertension, 10 [8.3%] cardiac arrest, 24[19.8%] congestive heart failure, 1[0.8%] each for neuromuscular respiratory failure and angioedema and 13[10.4%] stroke. Conclusions: Continuous TcCO2 monitoring correlates well with PaCO2 offering opportunities to reduce the need for physical patient contact for frequent arterial punctures and arterial line placement among critically-ill patients with acute respiratory failure. It is a valuable addition to non-invasive monitoring of PaCO2 especially those with COVID-19 and irrespective of shock states.