THE RELATION BETWEEN LEFT-VENTRICULAR WALL STRESS SHORTENING AND PRELOAD CHANGES IN VENTILATED PATIENTS

The relation between left ventricular end-systolic wail stress (ESWS) and the velocity of circumferential fibre shortening (Vcfs) was examin ed in four non-random groups with 12 patients each. In group A, preloa d was increased by the administration of hydroxyethylstarch 30 mL min( -1). In group B, preload was reduced by administering nitroglycerine 4 .0+/-0.8 mg h(-1). A change in pulmonary capillary wedge pressure by 3 mmHg was taken to be the end point for preload manipulation. To asses s a change in the relation between ESWS and Vcfs, patients in group C received adrenaline at an infusion rate of 4 g min(-1). Patients in gr oup D served as the controls. Geometric variables of ESWS and Vcfs wer e determined by transoesophageal echocardiography. A linear model was used to assess the relation between ESWS and Vcfs within each group by regression analysis, and analysis of covariance performed to detect s ignificance of intragroup and intergroup differences (P<0.005). No sig nificant changes were found during preload intervention. With adrenali ne, Vcfs increased significantly for a given ESWS. It is concluded tha t the relation between ESWS and Vcfs, in a multiple patient setting, i s independent of modest preload changes and may have the potential to indicate inotropic effects.