Question 19
This is the monitor strip of a 40 year old man 5 hours post Aortic Valve Replacement for severe Aortic Incompetence
The traces shown are (in order from the top to bottom):
• ECG
• ECG
• Arterial Pressure (AP; scale 0-100 mmHg)
• Pulmonary Artery pressure (PA; scale 0-50 mmHg)
• Central Venous Pressure (CVP; scale 0-30 mmHg)
• Pulse oximeter waveform.
(a) What are the abnormalities?
(b) What pathophysiological disturbances are revealed by these abnormalities?
College Answer
The abnormalities present include:
Sinus tachycardia, Pulsus Alternans, pulmonary hypertension, systolic hypotension, tricuspid regurgitation (large v waves), low calculated Systemic Vascular Resistance (about 500-600; though the estimate of cardiac output may be artificially elevated by the TR).
The specific pathophysiological disturbances revealed are:
Severe LV dysfunction and tricuspid regurgitation. The low SVR at this stage is most likely to be due to a systemic inflammatory response rather than sepsis.
Common problems related to lack of relevant detailed knowledge.
Discussion
This question is identical to Question 3.3 of the second 2009 paper.
However, the college answer here is more detailed, and comments are more snarky.
Not only that, but the examiners actually calculated the SVR ( 80 x (mean arterial pressure - mean right atrial pressure) / cardiac output) - that would be 80 x (63-23) / 5.7, or 561.4 dynes.s.cm-5
That would indeed be low. Normal is 700-1600.