Timing of pre-surgery dialysis matters, Stanford Medicine study finds

A study by Stanford Medicine researchers and collaborators has shown that a longer interval between dialysis and surgery is related to an increased risk of mortality during the following 90 days.

The study examined how the timing of hemodialysis, which filters blood in patients with end-stage kidney disease, affected post-operative mortality rates from all causes within 90 days. Longer intervals between dialysis and surgery were associated with higher mortality, while administering dialysis on the same day as surgery decreased that risk.

“While doctors recommended hemodialysis to occur the day before or day of surgery, this is the first study to show that the timing of hemodialysis before surgery matters,” said Vikram Fielding-Singh, MD, clinical assistant professor of anesthesiology, perioperative and pain medicine and lead author on the study.

A paper describing the study was published in the Journal of the American Medical Association Nov. 3. Eugene Lin, MD, an assistant professor of medicine at the University of Southern California, was the senior author on the study.

Off balance

The bean-shaped kidneys clean the blood, filtering out toxins as well as electrolytes consumed from food and drink such as potassium and sodium. The kidneys also regulate the amount of fluid in the body, removing about 1 to 2 liters each day through urination. For people with end-stage kidney disease, dialysis takes the place of working kidneys.

There are approximately 800,000 people with ESKD in the U.S., most of whom are receiving dialysis. Typically, patients undergo three sessions a week, which means that, between sessions, their bodies can accumulate about a gallon of excess fluid.

“As good as hemodialysis has become, it is still no substitute for having working kidneys,” Fielding-Singh said. “Living with ESKD is like having a balance problem, where tripping over something small can end up knocking you over. In this analogy, having surgery can be the small trip that leads to a big fall.”

He noted that patients with ESKD are more likely to have comorbidities that affect surgery outcomes such as diabetes or high blood pressure.

“Shortening the time between hemodialysis and surgery might help patients because the longer they go without hemodialysis, the more out of equilibrium they get,” Fielding-Singh said. “On the day after hemodialysis, the patient might have accumulated some toxins and some fluid, but not as much as two or even three days away from their last session.”

A dose-dependent effect

The retrospective study, based on the medical records of 346,828 Medicare patients with ESKD, analyzed the 90-day outcomes of 1,147,846 surgical procedures that occurred between January 2011 and September 2018. The procedures ranged from relatively minor ones, such as cataract replacement, to major operations, such as coronary bypass surgery. The research team examined mortality rates from any cause during the 90 days following the surgery.

They found a dose-dependent effect of the timing of dialysis before surgery: the longer the interval, the greater the mortality risk.

Patients who received dialysis the day before surgery had a lower mortality rate than those who had it two or three days prior. Undergoing dialysis two days before surgery was associated with a 14% increased risk of mortality relative to having it the day before, while having it three days before was associated with a 25% increase.

Administering dialysis on the same day as surgery mitigated the risk associated with a long interval. For patients who had their regularly scheduled dialysis two or three days before surgery, same-day dialysis reduced the mortality risk.

“These findings suggest that when possible, surgeries should be scheduled around hemodialysis or that hemodialysis should be performed right before the surgery,” Fielding-Singh said. “This study also points to a need to develop quality metrics around scheduling surgeries for patients with ESKD.”

Researchers from UCLA, Baylor College of Medicine, Kaiser Permanente and the University of Southern California also contributed to this study.

The research was funded by the National Institute of Diabetes and Digestive and Kidney Diseases; the Department of Anesthesiology and Perioperative Medicine at UCLA; the Stanford Department of Anesthesiology, Perioperative and Pain Medicine; the National Institute of General Medical Sciences (grant R35GM128672); and the American Society of Nephrology.