Treatable and Preventable, Kidney Specialist Says : Low Blood Sodium Draws Blame in Fatalities
The 15 previously healthy women were up and about, recovering quickly from their surgeries. But about two days after their operations, they suddenly developed generalized seizures. Within an hour, all had stopped breathing. Instead of going home, four of the women died in the hospital, and nine remain in persistent comas two to six years later.
The deaths and permanent brain damage were caused by severely low blood sodium, a condition that is often treatable and preventable and that can be diagnosed within minutes with a routine laboratory test.
Yet physicians initially suspected the correct diagnosis in only five of the women, leading to an average 16-hour delay in starting therapy.
The explanation of these cases, published in today’s New England Journal of Medicine, may help to save the lives of some patients who might otherwise die after surgery, according to the report’s author, Dr. Allen I. Arieff, a kidney specialist at the Veterans Administration Medical Center in San Francisco.
“I think this syndrome is going to turn out to be reasonably common when more people become aware of it,” said Arieff, who consulted on the 15 cases for physicians throughout the country over a 10-year period.
“Many physicians have not realized that low sodium can cause brain damage and death in perfectly healthy individuals. This problem, in my opinion, should almost never happen, if current practices in many hospital are changed.”
In all, about 4% of all surgical patients are estimated to develop mild cases of low blood sodium, which is known to physicians as hyponatremia. In most cases, the kidneys can correct the problem before symptoms develop. In severe cases, warning symptoms such as confusion, lethargy and sleepiness, sometimes develop before seizures and coma.
For several days after the operations, Arieff explained, the patients he studied routinely received an average of more than a gallon of sugar water through a vein each day.
The water contained little or no sodium, which is a key mineral contained in table salt and all body fluids. At the same time, the surgery stimulated the patients to secrete more of a hormone that interfered with their kidneys’ ability to turn the excess water into urine.
To compound the problem, the blood concentration of sodium had not been measured after the operation for all these patients, Arieff said. Such monitoring, which is generally considered good medical practice, might have prevented the catastrophes by allowing physicians to give the patients sodium before the life-threatening symptoms of low blood sodium developed.
The deaths and comas might also have been prevented if the physicians had given intravenous fluids that contained sodium, given less fluids or stopped the fluids when the patients began to eat, according to the study.
The patients Arieff studied were all employed or active housewives before undergoing such surgeries as repair of a torn shoulder ligament, cosmetic dental operations and gynecologic procedures.
The women died or suffered brain damage from a combination of factors, including brain swelling and lack of oxygen to the brain, after they stopped breathing. The two patients who partially recovered began to receive sodium replacement therapy within one hour of their first seizure. Both can walk with a cane; one has permanent double vision.
Arieff said he has consulted on a total of 23 cases in which these problems have developed and has discussed dozens of such cases with colleagues at medical meetings.
“In many of these cases, the family has never been told what happened,” Arieff said. “They were told the patient had a stroke or bleeding into the brain and that it was one of these things.”
