191

RESPIRATORY CENTERS ACTIVITY IN LIVER CIRRHOSIS.

S. Lauro,M.Ferrari*,E.Barozzi*,L.Caregaro,P.Amodio,P.Rizzini* l s t i t u t o di Medicina Clinica - UniversitA di Padova and *Clinica Medica - UniversitA di Verona

Respiratory hyperventilation is a well-known finding in liver cirrhosis. However, few

data are available about respiratory centers activity in cirrhotics. In the present study

we measured the respiratory centers activity in 24 cirrhotics and in 24 controls by two

tests particularly suitable for this purpose: the ventilatory response to hyperoxic

hypercapnia (mVE/PAC02) and the pressure developed during the'first 0.I second of breath-

ing against a closed mouthpiece (Pp.l). Moreover, all subjects were assayed for ventila-

tory function, for hemogasanalys~s and for the diffusing capacity for CO. Both the

mVE/PACO 2 and the PO 1 were higher in cirrhotics compared to controls (3.85+_0.93 v.s. 2.37

±0.45 1.min -I mmHg-l'- p<O.Ol - and 4.g8±1.66 v.s. 3.40+_1.31 cmH20 - p<0.05 - respecti- vely).

None of the two tests correlated with Pa02, PaC02, blood ammonia and the main bio- chemical indexes of liver disease.

Our data demonstrated that respiratory centers activity is increased in liver cirrho- sis, though i t s mechanism is not clear.

192

HAEMODYNAMIC EFFECTS OF PENTOBARBITAL ANAESTHESIA ON TWO MODELS OF PORTAL HYPERTENSION IN THE RAT S.S. Lee, C. Girod, D. Valla, D. Lebrec INSERM U24, HSpital Beaujon, Clichy, France.

Two widely used rat models for studying the circulatory changes of portal hypertensiol are the rat with portal vein stenosis and the rat with biliary cirrhosis due to bile duc ligation. However all the validation sudies of these models were done under genera anaesthesia. To determine the effects of pentobarbital on the hyperdynamic circulati~ in these models, 3 groups of 20 rats in the conscious and anaesthetized state were studied sham-operated, portal vein stenosis and biliary cirrhosis. Cardiac output (CO) and porta tributary blood flow (PTBF) were determined by radioactive microspheres. Systemic vascula: resistance (SVR) was calculated. A restraint apparatus was used for conscious rats pentobarbital 5 mg/kg ip, for the anaesthetized. Results are shown in the table (mean±SD).

Sham-operated Portal vein stenosis Biliary cirrhosis Conscious Anaesth. Conscious Anaesth. Conscious Anaesth.

CO ml/min 109.7±14.6 77.7±4.6 a 130.i±24.1 b 93.8±16.7a, b 160.0±33.1 b 97.5±6.8 a,b SVR dyn/s/cm 5 83.4±3.7 I17.8±4.7 a 69.4±0.4 b 99.4±7.6 a 50.5±7.5 b 81.2±9.0a,b PTBF ml/min 11.9±1.1 14.5±0.8 a 17.7±1.8 b 20.7±1.3 b 20.5±3.0 b 14.6±3.4 a Significantly different from a conscious rats and b corresponding sham-operated rats.

It is concluded that although pentobarbital induces marked systemic and splanchniq haemodynamic changes in normal, portal vein stenotic and biliary cirrhotic rats, thi! last group is particularly sensitive to its effects. Because anaesthesia normalizes thq previously augmented portal tributary blood flow in the biliary cirrhotic rat, it 1~ recommended that haemodynamic studies using this model be done in the conscious state.

$274