For serial testing, non-invasive transcutaneous monitoring (TCM) is definitely a preferred route. TCM is ideal for sleep studies, allowing any nocturnal variation to be observed and helping to determine whether the patient requires continuous positive airway pressure (CPAP) or assisted ventilation, as well as enabling progress during treatment to be monitored. It is also beneficial for cardiopulmonary exercise testing (CPET). The TOSCA monitor is very intuitive and easy to use, from fitting new membranes to storing the electrodes. Calibration is quickly and consistently performed. For patients, TOSCA is preferable to arterial blood sampling as it is completely painless.