SOUTH LAKE TAHOE, CALIF. — Bedside ultrasound should be used in the emergency department for patients with undifferentiated hypotension, Dr. John S. Rose said at an emergency medicine conference sponsored by the University of California, Davis.
The device can help identify three major physical causes of hypotension: fluid in the peritoneal cavity, fluid around the heart or gross cardiac abnormalities, and an abdominal aortic aneurysm, said Dr. Rose of the department of emergency medicine at UC Davis Medical Center, Sacramento.
“Ultrasound really will change your practice, not just in the trauma setting,” said Dr. Rose who described some hypothetical situations in which ultrasound might be used. They included a 24-year-old female who might have a ruptured ectopic pregnancy, a cancer patient undergoing treatment who could have pericardial effusion, and a 60-year-old patient with a systolic blood pressure of 70 mm Hg who might have an aortic aneurysm.
Because unexplained hypotension is potentially life threatening, one doesn't usually use restraint in ordering tests and studies in these cases, Dr. Rose said. And often there is no time to trundle the patient off to some other department for imaging studies.
“We do a lot of empiric things when they come in sick, so why not add [an ultrasound exam] on top of it?” he said.
“You can still do a comprehensive evaluation. The purpose behind the exam is just to think about the three reversible causes that you can find with ultrasound.”
Dr. Rose's proposed exam consists of three ultrasound views: a right upper quadrant view, the same as is used for a focused assessment with sonography for trauma, or FAST, examination; a cardiac assessment with a subxiphoid or parasternal long axis view; and an abdominal view.
The right upper quadrant view—which looks for fluid in the peritoneal cavity, in Morison's pouch between the liver and kidney—is not always sensitive in a trauma patient with limited bleeding. But it will be in the patient who has lost enough blood from the circulatory system to be hypotensive, and evidence bears this out, Dr. Rose said.
The cardiac assessment, which Dr. Rose calls a “limited echo,” is practical because it does not require extensive expertise, he said. It is a procedure that could be taught to an emergency physician in half an hour. One is simply looking to see that the heart is beating vigorously, that the left ventricle appears to be filling, and that there is no pericardial effusion.
The abdominal view follows the aorta all the way down, from substernum to the bifurcation, he said. As with the intraperitoneal findings, evidence shows that most abdominal aortic aneurysms associated with hypotension are apparent on ultrasound, and they are almost never missed in the emergency department.
Each of these assessments can be accomplished extremely quickly, and none needs a special transducer, he added.
“If you find free fluid, an effusion, or an [abdominal aortic aneurysm], I guarantee you are going to change the course on that patient,” Dr. Rose said. “You are going to do something different. This is not just for 'I'd like to know.'”