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Wave of the Future in Surgery

Sound waves provide better fluid monitoring during operation

WEDNESDAY, Oct. 2(HealthDayNews) -- Using reflected sound waves to measure the heart's pumping action lets anesthesiologists better monitor and control fluid and plasma levels during major surgery.

That's the conclusion of a new study in the October issue of Anesthesiology.

This Doppler technique also seems to speed patient recovery and reduce hospital stays, say Duke University Medical Center researchers. Patients have less post-operative nausea and vomiting, and they're able to eat solid foods much earlier.

Using the Doppler technique helps anesthesiologists ensure that fluid levels in a person having surgery don't drop below normal, a common occurrence during surgery. Being better able to monitor and maintain patient fluid levels during surgery means proper intestine functioning is maintained, resulting in improved patient recovery.

Fluids such as plasma, blood or synthetic agents called plasma expanders are given to people during surgery to compensate for blood loss and to maintain their blood pressure. Typically, these fluids are added in response to changes in blood pressure, urine output or heart rate.

In contrast to that reactive approach, Duke researchers tested a proactive method in this study. They used an esophageal Doppler monitor (EDM) that provided continuous readings of heart output.

A small ultrasound probe is put down the esophagus and positioned beside the aorta, which is the main artery out of the heart. The EDM measures reflections of sound waves directed at the aorta and provides information about blood volume being pumped out of the heart to the rest of the body.

Those measurements give an anesthesiologists an immediate indication of how much fluid they need to give the patient.

People in the EDM group were discharged six days after surgery, compared to seven days for the control group. The people in the EDM group also began tolerating solid foods three days after surgery, compared to five days for those in the control group. And more than twice the people in the control group had severe post-operative nausea and vomiting than the people in the EDM group, the study says.

More information

Learn more about anesthesia at the American Society of Anesthesiologists.

SOURCE: Duke University Medical Center, news release, Oct. 2, 2002
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