Transcutaneous Carbon Dioxide Monitoring Against Arterial Blood Gas Analysis for Guiding Acute Non-invasive Ventilation: A Systematic Review and Meta-Analysis

<bold>Background:</bold> Acute hypercapnic respiratory failure (AHRF) is a medical emergency that requires prompt ventilatory support and reliable monitoring of carbon dioxide.Arterial blood gas (ABG) analysis is the reference test for PaCO₂, but it is invasive, only provides intermittent results, and is often painful for patients. Transcutaneous carbon dioxide (TcCO₂) monitoring offers continuous,noninvasive measurement,though its accuracy and clinical value during acute noninvasive ventilation (NIV) remain debated. <bold>Methods:</bold> We performed a systematic review and meta-analysis in line with PRISMA-DTA guidelines. . Studies were eligible if they compared TcCO₂ with PaCO₂ in adults receiving NIV. Two reviewers independently screened records, assessed study quality with QUADAS-2,and extracted data on correlation, agreement, tolerability, and clinical impact. <bold>Results:</bold> Seven studies enrolling just over 400 patients were included.Correlation between TcCO₂ and PaCO₂ was consistently high (0.85–0.97), with a pooled estimate of r=0.91.Bland–Altman plots showed acceptable bias and clinically useful limits of agreement. TcCO₂ monitoring was well tolerated, lowered the need for repeated ABGs,and provided real-time information that guided bedside management. No device-related adverse effects were reported. <bold>Conclusion:</bold> TcCO₂ shows strong agreement with PaCO₂ and appears to be a safe and practical adjunct to ABG analysis in adults on NIV for AHRF.Continuous, noninvasive monitoring may improve comfort and workflow by reducing invasive sampling. Larger, prospective studies are needed to confirm its impact on outcomes and assess cost-effectiveness.