26 July 2006

Screwdriver + Chest = Pericardial Centesis

A day of teachable moments in the ER...

A patient was helicoptered into our ER from another ER (why is not exactly clear) with a stab wound to the left chest caused by a screwdriver. The patient had marked jugular distension (bulging neck veins), extreme hypotension (ie, no blood pressure), and muffled heart sounds. What does this (Beck's triad) of symptoms indicate? Cardiac tampenade!

The patient was bleeding into the sac around his heart (the pericardium) and this was putting pressure on the heart itself. Since there is no space around the heart, it cannot expand when filling with blood, limiting the volume of blood that can enter the ventricle. This means less blood is being pushed out with each contraction (decreased stroke volume and thus low blood pressure) and a build of of venous blood in the neck (think of a traffic jam in your superior vena cava).

To treat this particularly life threatening issue, the blood is drained from the pericardium while stabilizing the patient to get them to the OR. This draining procedure is the pericardial centesis and they performed it on the patient twice.

Had the patient been registering a blood pressure, we probably also would have seen pulsus paradoxus: a 10 point drop is systolic (top number- ventricular contraction) blood pressure on inhalation (breathing in). When you breathe in you are actually expanding your chest to create a highly negative pressure (4x less that the atmosphere) inside your lungs. This pulls air into your lungs (goes from high pressure to low) but it also helps pull thoracic blood (blood in your torso) back towards your heart. The thing is, if your heart can't expand because your chest is filled with blood, then filling the right side with venous blood leaves very little room on the right side for oxygenated blood coming from your lungs. Thus, even less blood is pushed out of the left side on contraction and you have an even lower blood pressure.

The trouble with working in the ER is that you don't "follow" your patients. He was alive when he got to the OR, I have no idea if he still is.

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