A 70-year-old male with past medical history of mild-moderate mitral regurgitation and moderate-severe tricuspid regurgitation, COPD, and secondary pulmonary hypertension presents to the Emergency Department with a fever and new cough. Vitals on presentation are notable for a blood pressure of 80/43, temperature of 38.7°C, and oxygen saturation of 80% on room air, which improves modestly with 6 L oxygen by nasal cannula. Chest radiograph shows multifocal airspace opacities suggestive of pneumonia, but not pulmonary edema. He is transferred to the ICU for intubation. Examination is also notable for cool extremities with +1 symmetric lower extremity edema. In determining whether to administer fluids to this patient to augment his mean arterial pressure, which of the following techniques would be LEAST helpful?
A. Pulmonary Arterial Catheter (PAC)Correct Answer: B
Measures of fluid responsiveness can be separated into static and dynamic measures. The static measures include: CVP, pulmonary capillary wedge pressure, and clinical static endpoints (heart rate, blood pressure, etc). Dynamic measures include: pulse pressure variation, stroke volume variation, IVC collapsibility, and response to passive leg raise. Each of these has their own strengths and weaknesses, with dynamic measures generally thought to perform better than static measures. The 2016 surviving sepsis guidelines recommend using dynamic indices of volume responsiveness to guide volume resuscitation in sepsis.
The patient in the question has pulmonary hypertension and significant tricuspid regurgitation, which would confound interpretation of CVP measurements, if the CVP were to be used as a proxy for RV preload. However in patients with RV failure or severe TR, the CVP is falsely elevated and does not give an accurate representation of preload. The other measures of fluid status such as pulmonary artery wedge pressure (measure through a pulmonary artery catheter) measures left ventricular preload and thus a better representation of systemic preload than CVP. Dynamic indices such as pulse pressure variation, stroke volume variation, and passive leg raise have been shown to be superior measures for determining volume responsiveness.
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