[Physiological assessment and management of post-COVID patients with normal cardiopulmonary imaging and functional...

Contributing to elucidate the pathophysiology of dyspnoea and exertion intolerance in post-COVID syndrome patients with normal cardiopulmonary imaging and functional tests at rest, while determining their fitness and level of endurance in order to individualize working parameters for physical rehabilitation.

After an anamnesis and clinical examination at rest, 27 subjects (50±11.9 years) (14 women) with post-COVID syndrome of more than 6 months of evolution performed a continuous maximal-incremental graded cardiopulmonary exercise test (CPET) with breath-by-breath gas-exchange monitoring and continuous ECG registration, on an electromagnetically braked cycle ergometer. The values obtained were compared with those of reference, gender or controls, using the Chi-square, t-Student or ANOVA test.

The clinical examination at rest and the CPET were clinically normal and without adverse events. Reasons for stopping exercise were leg discomfort. It is only worth noting a BMI=29.9±5.8kg/m² and a basal lactate concentration of 2.1±0.7mmol/L. The physiological assessment of endurance showed the following results relative to predicted VO_2máx: 1)peakVO₂=80.5±18.6%; 2)VO₂ at ventilatory threshold1 (VO₂VT1): 46.0±12.9%; 3)VO₂VT2: 57.2±16.4%; 4)working time in acidosis: 5.6±3,0minutes; and 5)maximum lactate concentration: 5.1±2.2mmol/L.

The CPET identified limited aerobic metabolism and early increase in glycolytic metabolism as causes of dyspnoea and exercise intolerance, determined fitness for physical rehabilitation, and individualized it based on the level of endurance.