Cardiopulmonary exercise capacity and limitations 3 months after COVID-19 hospitalisation

Skjørten, Ingunn; Ankerstjerne, Odd Andre Wathne; Trebinjac, Divna; Brønstad, Eivind; Rasch-Halvorsen, Øystein; Einvik, Gunnar; Lerum, Tøri Vigeland; Stavem, Knut; Anne, Edvardsen; Ingul, Charlotte Björk

RATIONALE: This study aimed to describe cardiopulmonary function during exercise 3 months after hospital discharge for COVID-19 and compare groups according to dyspnea and intensive care unit (ICU) stay. METHODS: Participants with COVID-19 discharged from five large Norwegian hospitals were consecutively invited to a multicentre, prospective cohort study. In total, 156 participants (mean age 56.2 years, 60 females) were examined with a cardiopulmonary exercise test (CPET) 3 months after discharge and compared to a reference population. Dyspnea was assessed using the modified Medical Research Council dyspnea scale (mMRC). RESULTS: Peak oxygen uptake (V̇O(2)) <80% of predicted was observed in 31% (n=49). Ventilatory efficiency was reduced in 15% (n=24), while breathing reserve <15% was observed in 16% (n=25). Oxygen pulse <80% of predicted was found in 18% (n=28). Dyspnea (mMRC ≥1) was reported by 38% (n=59). These participants had similar peak V̇O(2) (p=0.10), but lower mean peak (sd) V̇O(2)·kg(−1) % of predicted compared to participants without dyspnea (mMRC 0) (76 (16)% versus 89 (18)%, p =0.009) due to higher body mass index (p=0.03). In participants treated at ICU versus non-ICU, mean peak (sd) V̇O(2)% of predicted were 82 (15)% and 90 (17)% (p=0.004), respectively. Ventilation, breathing reserve, and ventilatory efficiency were similar between the ICU and non-ICU groups. CONCLUSIONS: One- third experienced peak V̇O(2) <80% of predicted 3 months after hospital discharge for COVID-19. Dyspneic participants were characterised by lower exercise capacity due to obesity and lower ventilatory efficiency. Ventilation and ventilatory efficiency were similar between ICU- and non-ICU-treated participants.