A 30-Minute nailbed scan could reveal how lung treatments work

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: For inpatient enrolment: * Suspected diagnosis of group 1,3 or 4 pulmonary hypertension undergoing inpatient assessment at nationally designated centre * Age \> 18 years For follow up scanning of those enrolled as an inpatient: * Confirmed diagnosis of pulmonary hypertension assessed at nationally designated centre fulfilling criteria for group 1, 3 or 4 disease * Commencing PH targeted therapy, specifically one or more of: a phosphodiesterase 5 inhibitor (PDE5i), an ET receptor antagonist (ERA), parenteral prostanoid therapy, selexipag, riociguat, sotatercept. For outpatient enrolment * Confirmed diagnosis of pulmonary hypertension assessed at nationally designated centre fulfilling criteria for group 1, 3 or 4 disease * Age \> 18 years * Escalating PH targeted therapy, specifically one or more of: a phosphodiesterase 5 inhibitor (PDE5i), an ET receptor antagonist (ERA), parenteral prostanoid therapy, selexipag, riociguat, sotatercept. Target of \> 25% of patients recruited at diagnosis and to have an SSc-spectrum disorder fulfilling either ACR/EULAR 2013 or VEDOSS (very early diagnosis of SSc) criteria. Target of \> 25% of patients recruited at diagnosis and to have non-SSc group 1 (PAH) diagnosis (as determined by national MDT decision). Exclusion Criteria: * Patients with confirmed group 2 or group 5 pulmonary hypertension * Patients \< 18 years of age * Patients unable to participate in nailbed microscopy (through e.g. amputation, severe contractures or other musculoskeletal issues). * (From follow up) Patients not being commenced on pulmonary vasodilator therapy at the point of diagnosis. * Patients already on maximal PH therapy * Patients lacking capacity to consent to participation * Patients who are non-fluent English speakers, where suitable translation cannot be found within a time frame that makes the study feasible. * Patients with a life expectancy \< 4 months * Patients who have consumed nicotine or caffeine within the last 4 - 6 hours * Patients wearing nail polish / varnish/ extensions that preclude adequate nailbed visualisation.