End-tidal carbon dioxide levels in patients with post-concussion syndrome during neurocognitive and physical tasks compared to a normative control group.

PRIMARY OBJECTIVE

Recent findings suggest breathing may negatively affect performance after concussion. The aim of the study was to examine group differences between individuals with and without post-concussion syndrome (PCS) in end-tidal carbon dioxide (ETCO) and respiratory rate (RR) during neurocognitive and physical tasks.

HYPOTHESIS

Individuals in the PCS group will have elevated ETCO and lower RR compared to the control group.

METHODS

A quasi-experimental study was used in which a capnography unit collected ETCO and RR breathing data from 22 participants (control = 17; PCS = 5) during rest, the completion of the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) battery and while slow and fast walking. Four repeated measures mixed factorial ANOVAs, with an alpha level set at p ≤ 0.05, were used to examine group and task differences.

RESULTS

Both groups displayed similar breathing responses to cognitive and physical stress; however, PCS participants had significantly elevated ETCO throughout the study (during rest, the ImPACT and while walking) compared to the control. Conversely, no significant group differences were found in RR.

CONCLUSION

Cerebral physiological alterations and deficits in the autonomic nervous system may cause abnormal ETCO in individuals after concussion. Future research evaluating breathing patterns in PCS may be warranted.