UC Riverside

The emergence of SARS-CoV-2 resulted in millions of hospitalizations and 6.9 million deaths to-date. Many individuals who recover from COVID-19 report prolonged dyspnea, with this symptom persisting for months following recovery. Furthermore, data suggests COVID-19 has been linked to systemic and neuronal inflammation which may have downstream impacts on the neural control of breathing. As such, we hypothesized that individuals recovered from COVID-19 may exhibit changes in their ventilatory chemosensitivity to CO2 and/or O2 and that these changes may be linked to higher levels of systemic inflammation. To test this hypothesis, we measured baseline ventilatory patterns and chemoreflex sensitivity using a modified rebreathing technique in individuals recovered from COVID-19 (n = 77), as well as an age and sex-matched control group (n = 41). Peripheral blood samples were also collected for inflammatory profiling. Recovered participants demonstrated lower ventilatory responses to hypercapnia, particularly under a combined hypoxic stimulus (p = 0.032). Furthermore, higher levels of plasma IL-1β was associated with higher hypoxic ventilatory responses among the recovered group (R = 0.44, p = 0.004), highlighting a potential link between acute systemic inflammation and depressed ventilatory chemoreflex sensitivity. When separated by time-post-recovery, we observed a decreased ventilatory recruitment threshold (VRT) beginning at 4 months post-recovery (p = 0.019) that returned to baseline after one-year post-recovery. A decrease in sensitivity to CO2 was also noted immediately after recovery with no return to baseline observed within the two-year tested time frame (p = 0.023). Overall, this data indicates that (1) COVID-19 may have impacts on the neural control of breathing, and (2) systemic inflammation may play a role in modulating ventilatory chemoreflex sensitivity. These findings may have implications for the pathology of long-COVID symptoms, including sleep disturbance and prolonged dyspnea.