What's in a beat?

Excerpt

I remember being much taken by Ray Raper and Bill Sibbald's [3] classic exposé of the folly of equating end-diastolic pressure to end-diastolic volume without regard to ventricular compliance, or changes therein. Yet to this day I see and hear the same misunderstandings repeated time and again in both daily practice and at meetings, even by 'experts' who perhaps ought to know better! Accordingly, many hypovolaemic patients remain under-resuscitated with fluid on the basis of a high pulmonary artery wedge (or central venous) pressure and may thus be exposed to premature and/or unnecessary inotropic stimulation. Likewise, the inaccuracy of thermodilution as a measure of cardiac output with concurrent tricuspid regurgitation [4, 5] or low output states [6] is far from universally recognized. Yet even the aware may remain blissfully unaware that pulmonary hypertension, a common finding in the critically ill patient with respiratory failure, is measured echocardiographically by assessing the degree of tricuspid regurgitation [7]. I do not exclude myself from wallowing unknowingly in my own particular pits of ignorance, yet at least I recognize its high likelihood! …