Abnormal hyperventilation in patients with hepatic cirrhosis: role of enhanced chemosensitivity to carbon dioxide.
BACKGROUND
Patients with hepatic cirrhosis frequently show idiopathic hyperventilation at rest, despite no concomitant cardiopulmonary disease. The aim of the study was to determine whether altered chemosensitivity either to hypoxia or hypercapnia could underlie inappropriate hyperventilation in cirrhotic patients.


METHODS
We consecutively recruited 30 biopsy proven cirrhotic patients equally distributed in the three Child's classes A, B and C (age 54 ± 8 years, mean ± SD). All patients underwent evaluation of chemosensitivity to hypoxia and to hypercapnia and blood sampling for brain natriuretic peptide, norepinephrine and progesterone, besides full clinical characterization. We also recruited 10 age- and gender-matched healthy controls (age 55 ± 7 years).


RESULTS
Overall, 18 patients (60%) showed an increased chemosensitivity to carbon dioxide (CO(2)), while 8 patients (27%) showed enhanced chemosensitivity to hypoxia. Child's class C patients had lower arterial partial pressure of CO(2) (PaCO(2)), higher rest ventilation, increased chemosensitivity to hypercapnia, plasma level of norepinephrine and serum progesterone levels when compared to class A patients and controls (all p < 0.05). Rest ventilation was positively related to pH (R = 0.41, p = 0.023), chemosensitivity to hypercapnia (R = 0.54, p = 0.002), and progesterone (R = 0.53, p = 0.016) and negatively to PaCO(2) (R = 0.61, p < 0.001), but not to hemoglobin level and chemosensitivity to hypoxia. Chemosensitivity to hypercapnia was positively related to PaCO(2) (R = 0.74, p < 0.001), serum progesterone (R = 0.50, p = 0.016), and to plasma norepinephrine (R = 0.57, p = 0.004).


CONCLUSIONS
Enhanced chemosensitivity to hypercapnia was found in more decompensated cirrhotic patients and was associated with sympathetic overactivity and elevated serum progesterone, likely representing a key mechanism underlying the "unexplained" hyperventilation observed in such patients.
Passino
Claudio
C
Division of Cardiovascular Medicine, Fondazione G. Monasterio CNR-Regione Toscana, Pisa, Italy. passino@ifc.cnr.it
Giannoni
Alberto
A
Mannucci
Francesca
F
Prontera
Concetta
C
Filipponi
Franco
F
Carrai
Paola
P
Emdin
Michele
M
Catapano
Giosuè
G
D002245:Carbon Dioxide / Q000502:physiology*; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000209:etiology*; D008103:Liver Cirrhosis / Q000150:complications*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
D002245:Carbon Dioxide