Archive for the ‘Aortic Pressure’ Category

We saw no difference between changes in EDA vs ESA within each subgroup. Because the absolute value of the end-systolic volume must be less than that of the end-diastolic volume, an equal decrease in both values might be interpreted differently if one used either the absolute volume or a percentage change. We used the absolute […]

As a final note of validation, Leithner et al demonstrated in normal subjects that lung distention to levels similar to those used in our study reduced LV end-diastolic volume and induced an anterior rotational movement on the heart. They used MRI techniques and thus were limited to end-expiratory analysis as lung volume was progressively increased […]

TEE has limited application during positive-pressure ventilation because the image can shift out of the region of interest. This is why we analyzed only high-quality images after two independent observers using accepted criteria reviewed them. The overall percentage of good-quality images in our study is nevertheless comparable to other studies in which the ABD technique […]

Although care was taken to study similar types of subjects undergoing comparable surgical stresses, marked variability in response among subjects occurred. This variation might be a reflection of differing intravascular volume status, as well as differing LV systolic and diastolic function. EDA as an estimate of LV filling volume varied from 3.4 to 26.4 cm2 in […]

Our observations and those from Figure 6 in the study of Abel et al demonstrate less variation in SAP during the open chest condition rather than during the closed chest condition. Based on observations in three subjects, Perel et al and Pizov et al hypothesized that the absence of variation in SAP may indicate the […]

We observed that changes in SAP during positive-pressure ventilation in humans cannot be explained by proportional changes in LV volume. The effects of positive-pressure ventilation on LV volume and SAP are complex and not interpretable by a single mechanism. If SAP increases relative to apneic values during ventilation, it does so during the inspiratory phase, […]

Effect of Open and Closed Chest Conditions In both closed and open chest conditions (Fig 6), increases in SAP (A up) occurred in phase with the positive-pressure inspiration (86% open and 82% closed), whereas the A down occurred in expiration. The A down was greater in the closed than in the open chest condition (Table […]