Some women die or suffer brain damage after routine surgery because of an easily preventable episode of low blood salt, a study of 15 such cases concludes.

"I can't estimate how common this is," said Dr. Allen I. Arieff of the University of California at San Francisco, "but I think a lot of people who have elective surgery die of this, and few people ever suspect the cause."

Surgical patients are commonly given intravenous sugar water after surgery to provide nourishment and prevent dehydration. But in some women, surgery triggers a hormonal response that forces the body to retain water. That, combined with the extra intravenous fluid, dilutes the sodium in the blood and throws the body's chemistry out of balance.

Routine intravenous use of a salt solution after surgery would prevent the condition, Arieff writes in the current New England Journal of Medicine.

In the 15 cases Arieff reviewed, this condition, known as hyponatremia, was initially blamed in only five patients. All of the women were apparently doing well after surgery when suddenly they suffered seizures, stopped breathing and entered comas. Four died, two had limb paralysis and the rest were left in permanent vegetative states. Hereditary Condition Linked To Some SIDS Deaths

Children of people with an inherited breathing problem may be at greater than average risk of sudden infant death syndrome, California researchers have found.

Examinations of six infants, from five families, who suffered SIDS-like episodes but survived showed that all had unusually small upper airways. Examinations of the infants' siblings, parents and grandparents revealed a family tendency toward the abnormality. In adults, it can cause frequent breathing interruptions during sleep, a condition called apnea, and snoring.

Doctors believe there are probably several causes of SIDS, which mysteriously claims 8,000 infants a year in the United States. This small Stanford University study, which looked at six infants from five families, may explain why some of these children die.

The infants studied were treated at Stanford after their parents checked them in their cribs "when they were supposed to be asleep, and they were found to be blue or very pale and not breathing," said Dr. Christian Guilleminaut, who published his findings recently in The Lancet, a British medical journal.

All of the five families had lost one or two children to SIDS within the three generations studied.

All of the six infants in the study eventually had tonsillectomies, and two had additional surgery to enlarge their airways. While none still has sleep apnea, two are intermittent snorers. On the Pulse

Why so much green in the hospital? The American Journal of Nursing says British army doctors complained that after looking at red blood during surgery, they saw splotches of the reverse color, green, when they glanced up at white walls. The solution was to paint operating room walls green and wear green surgical garb. The tradition continues . . . Americans are eating more poultry and less red meat than they did a decade ago. Per capita consumption of chicken and turkey was up 43 percent since 1970, the Food Institute reports, while beef consumption dropped 8 percent despite lower prices. White chicken and turkey meat has considerably less fat than most beef and for that reason is considered more healthful . . .