{{Cite journal| doi = 10.1038/s41598-021-89913-x| issn = 2045-2322 (Electronic) 2045-2322 (Linking)| volume = 11| issue = 1| pages = 10391| last1 = Doppmann| first1 = P.| last2 = Meuli| first2 = L.| last3 = Sollid| first3 = S. J. M.| last4 = Filipovic| first4 = M.| last5 = Knapp| first5 = J.| last6 = Exadaktylos| first6 = A.| last7 = Albrecht| first7 = R.| last8 = Pietsch| first8 = U.| title = End-tidal to arterial carbon dioxide gradient is associated with increased mortality in patients with traumatic brain injury: a retrospective observational study| journal = Sci Rep| date = 2021-05-19| pmid = 34001982}}