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Editor,—I read with interest the short case report by Betts and Radvan on the use of contrast echocardiography during pericardiocentesis.1 I would like to suggest a much simpler and cheaper method of differentiating pericardial space from a cardiac chamber during pericardiocentesis.
For the past 45 years I have always included an ampul of dehydrocholate and an ampul of lobeline on the sterile pericardiocentesis tray.2 Whenever the needle encounters blood or bloody fluid, one is faced with the problem of whether it is the pericardial cavity or a cardiac chamber that the needle tip has entered. Before aspiration is attempted, either dehydrocholate or lobeline in case of an obtunded patient should be injected. If the patient gives a typical response as in an ordinary circulation time determination, the needle tip must be in the cardiac chamber and should be withdrawn promptly. A negative response ensures an extracardiac location of the needle tip, and further aspiration or air injection for pneumopericardium (for assessment of the pericardial thickness) could be carried out with impunity. In parts of the world where dehydrocholate or lobeline might not be readily available, magnesium sulfate might be substituted.
A circulation time determination during pericardiocentesis provides a simple, safe, and accurate bedside method of differentiating between bloody pericardial fluid and intracardiac blood. It is also far less expensive than echocardiography. Furthermore, it is a much more expedient procedure during an emergency in suspected cardiac tamponade, especially when an echocardiographic machine is not readily available.
This letter was shown to the authors, who reply as follows:
We note with great interest the suggestion of dehydrocholate injection as a way of differentiating the pericardial space from penetration into a cardiac chamber. It is an astute use of an old method of investigating for heart failure. Dehydrocholate, a bile salt, would be injected into a peripheral vein and the time taken for it to reach the tongue, when a bitter taste suddenly appeared, was measured as the circulation time, an index of ventricular function. Although we applaud its ingenuity we cannot recommend it as a substitute for more modern techniques. It is the advent of echocardiography, fluoroscopy, and haemodynamic monitoring that has increased the safety of pericardiocentesis. Invariably echocardiography will have been used to diagnose or confirm the presence of an effusion, identify the best route of approach, and demonstrate successful drainage after the procedure. In an emergency, the patient’s response to dehydrocholate may not be reliable. While dehydrocholate and circulation time measurement may be used as an adjunct to echocardiography during pericardiocentesis, it should not be used as an alternative.