The Arterial Pressure Waveform During Acute Ventricular Failure and Synchronized External Chest Compression

Publisher Website
Google Scholar
Abstract
Methods for mechanical cardiac support by intermittent increases in the intrathoracic pressure have recently been described. In the present study the responses of the arterial pressure waveform to mechanical ventilation with and without synchronized extent chest compression (SEC) in the presence of acute ventricular failure (AVF) were evaluated by measuring the systolic pressure variation (SPV). SPV, the difference between the maximal and minimal values of systolic blood during a single positive pressure breath, consists of .DELTA.up and .DELTA.down components when systolic blood pressure during a short apnea is used as reference value. During intermittent positive pressure ventilation (IPPV) alone, AVF caused SPV to decrease significantly from 8.8 .+-. 4.0 to 5.7 .+-. 1.9 mm Hg, and further to 3.1 .+-. 1.1 mm Hg after volume loading (P < 0.02). The decrease in SPV was due to a significant decrease in the .DELTA.down component, whereas the .DELTA.up became the major component of the reduced SPV. The application of SEC caused significant increases in the .DELTA.down, .DELTA.up, and overall SPV during AVF without volume loading. However, during AVF with volume loading, SEC increased only the .DELTA.up component of the SPV, signifying a transient increase in the left ventricular stroke output. It is concluded that the disappearance of the .DELTA.down component of the SPV is characteristic of congestive heart failure. Analysis of the arterial waveform offers a readily available monitoring tool for the differentiation of the possible effect on increased intrathoracic pressure. The appearance of a prominent .DELTA.down signifies inadequate preload and possible reduction in cardiac output, whereas a significant .DELTA.up component is the reflection of a true mechanical cardiac support.