ReAcT CO2: A Study to Assess TcCO2 to Guide Acute NIV

Arterial blood sampling is needed to monitor carbon dioxide and PH but is often painful. The aim of this study is to determine whether continuous carbon dioxide monitoring with a skin probe reduces the need for arterial blood sampling by at least 30%. The investigators will also study the safety and effectiveness of skin probe monitoring to manage non-invasive ventilation (NIV).

Inclusion Criteria:Patients aged18 years and over with hypercapnia, requiring acute NIV and who are admitted to the Emergency Department or Medical HDU and, who need arterial blood sampling for clinical reasons.Recruited ideally within 4 hours (but no later than 8 hours) of initiation of acute NIV in hospital.Exclusion Criteria:Reduced level of consciousness or agitation.Metabolic or mixed acidosis, serum bicarbonate < 24 mmol/L.Haemodynamic instability or reduced skin perfusion.Patients requiring more than 6litres/min (ormorethan60%) inspired oxygen through ventilator to maintain SpO2 of 88-92%.Need for multi-organ support e.g. inotropes or vasopressors or renal replacement therapyArterial pH equal or less than 7.1 or carbon dioxide levels >15kPa as they are at risk of NIV failure and likely to require mechanical ventilation.Participating in any other interventional study