References: Tantucci et al, 2001
Tantucci C, Bottini P, Fiorani C, Dottorini ML, Santeusanio F, Provinciali L,
Sorbini CA, Casucci G
Cerebrovascular reactivity and hypercapnic respiratory drive in diabetic
J Appl Physiol 2001, 90: p. 889896.
Clinica di 1Semeiotica e Metodologia Medica and Neurologia e
Neuroriabilitazione, University of Ancona, and Dipartimento di Medicina Interna
e Scienze Endocrino-Metaboliche, University of Perugia, Italy
Because abnormalities in cerebrovascular reactivity (CVR) in subjects with
long-term diabetes could partly be ascribed to autonomic neuropathy and related
to central chemosensitivity, CVR and the respiratory drive output during
progressive hypercapnia were studied in 15 diabetic patients without (DAN2) and
30 with autonomic neuropathy (DAN1), of whom 15 had postural hypotension (PH)
(DAN1PH1) and 15 did not (DAN1PH2), and in 15 control (C) subjects. During CO2
rebreathing, changes in occlusion pressure and minute ventilation were assessed,
and seven subjects in each group had simultaneous measurements of the middle
cerebral artery mean blood velocity (MCAV) by transcranial Doppler. The
respiratory output to CO2 was greater in DAN1PH1 than in DAN1PH2 and DAN2 (P ,
0.01), whereas a reduced chemosensitivity was found in DAN1PH2 (P , 0.05 vs. C).
MCAV increased linearly with the end-tidal PCO2 (PETCO2) in DAN1PH2 but less
than in C and DAN2 (P , 0.01). In contrast, DAN1PH1 showed an exponential
increment in MCAVwith PETCO2 mainly .55 Torr. Thus CVR was lower in DAN1 than in
C at PETCO2 ,55 Torr (P , 0.01), whereas it was greater in DAN1PH1 than in
DAN1PH2 (P , 0.01) and DAN2 (P , 0.05) at PETCO2 .55 Torr. CVR and occlusion
pressure during hypercapnia were correlated only in DAN1 (r 5 0.91, P , 0.001).
We conclude that, in diabetic patients with autonomic neuropathy, CVR to CO2 is
reduced or increased according to the severity of dysautonomy and intensity of
stimulus and appears to modulate the hypercapnic respiratory drive.