Systolic pressure measurement in the ascending aorta: augmentation at the aortic cannula sideport

What's new in monitoring the coronary surgery patient?

Monitoring has been extensively reviewed in most textbooks of cardiothoracic surgery and anaesthesia, particularly in the recent textbooks on monitoring edited by Carol L Lake 1 and Casey D Blitt 2 and in the Journal of Clinical Monitoring. Although monitoring properly includes both pre- and postoperative periods, this review will concentrate exclusively on the operative period. I will also concentrate on new approaches or information which relate to more traditional approaches to monitoring. The emphasis in this review will not be on what we can monitor, but rather on what we should monitor. In this regard, I will analyse accuracy and identify sources of error and try to answer the following questions. Does the device or parameter measure (monitor) what we want to know? Does it improve patient outcome and safety? Is it cost-effective? Unfortunately, data are not always available to answer all these questions at present, but hopefully the discussions will make us aware of what we do and do not know, and what we should look for in the near future.

Left ventricular end-systolic pressure estimated from measurements in a peripheral artery

Aortic and radial arterial pressure measurements were compared after cannulation and before cardiopulmonary bypass in 26 patients scheduled for coronary artery bypass grafting. The radial artery blood pressure range was 89 to 147 mm Hg systolic and 44 to 75 mm Hg diastolic. A difference was found between the central and peripheral dicrotic notch pressures, the former being 7.9 +/- 2.7 (SD) mm Hg higher than the latter. When 8 mm Hg was added to the notch pressure measured in the radial artery to construct a calculated end-systolic pressure, there was good agreement with the centrally measured notch pressure. The mean difference was -0.15 mm Hg with a 95% confidence interval of -1.2 to 0.9 mm Hg. It was not possible to calculate peak systolic aortic pressure with the same accuracy from the systolic and diastolic pressure measurements in the radial artery. It is concluded that left ventricular end-systolic pressure measured as the aortic dicrotic notch pressure can be calculated from the dicrotic notch pressure in the radial artery with reasonable accuracy.