RESPIRATORY MECHANICS IN PATIENTS WITH TENSE CIRRHOTIC ASCITES

Lung volumes are decreased by tense ascites and increase after large v olume paracentesis (LVP), The overall effect of ascites and LVP on the respiratory function is poorly understood, We studied eight cirrhotic patients with tense ascites before and after LVP, Inspiratory muscle force (maximal transdiaphragmatic pressure (Pdi,max), and the lowest p leural pressure (Ppl,min)) was assessed while the patients were seated , Rib cage and abdominal volume displacements, as well as pleural and gastric pressures were measured during quiet breathing while the patie nts were supine. Pdi,max and Ppl,min were normal and did not change af ter LVP (from 843+/-19.7 to 85,2+/-17,0 cmH(2)O and from 683+/-19.7 to 74+/-15.9 cmH(2)O, respectively), The abdominal contribution to the g eneration of tidal volume was greater than that of the rib cage (79 vs 21%), a pattern which did not change after LVP (73 and 27%), Before L VP, tidal swings both of pleural pressure (Ppl,sw) and transdiaphragma tic pressure (Pdi,sw) were large (15,3+/-4,3 and 18.5+/-3.9 cmH(2)O, r espectively) and the load on inspiratory muscles was increased as a co nsequence of elevated dynamic elastance of the lung (El,dyn) (11.4+/-2 .6 cmH(2)O . L-1) and (''intrinsic'') positive end-expiratory pressure (PEEPi) (4.3+/-3.5 cmH(2)O). LVP reduced the load on the inspiratory muscles, as shown by the significant decrease in Ppl,sw (10.6+/-.2.0 c mH(2)O), Pdi,sw (12.8+/-3.0 cmH(2)O), El,dyn (10,0+/-2.0 cmH(2)O . L-1 ) and PEEPi (1,1+/-1.3 cmH(2)O), The amount of fluid removed was close ly related to changes in Ppl,sw and PEEPi, We conclude that the streng th of the inspiratory muscles is normal or reduced in seated cirrhotic patients, In the supine position, tense ascites results in an increas e in lung elastic load and development of positive end-expiratory pres sure, with a consequent overload and increased activation of inspirato ry muscles, Large volume paracentesis decreases overloading and activa tion, but does not change the strength of the inspiratory muscles.