June 22, 2018
2 min read

Nitric oxide during cardiopulmonary bypass boosts kidney outcomes

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Patients undergoing multiple valve replacement with prolonged cardiopulmonary bypass who were given nitric oxide had a decreased risk for acute kidney injury, worsening of chronic kidney disease and major adverse kidney events, according to a study published in the American Journal of Respiratory and Critical Care Medicine.

“Previous studies showed that prolonged cardiopulmonary bypass causes disruption of circulating red blood cells and the release of hemoglobin, which can cause acute kidney injury, leading to kidney failure and the need for long-term hemodialysis,” Lorenzo Berra, MD, medical director of respiratory care at Massachusetts General Hospital and assistant professor at Harvard Medical School, said in a press release. “We tested whether administration of nitric oxide, a gas normally produced by cells in the lining of blood vessels, might render hemoglobin ‘inert,’ thereby decreasing the risk of both acute and chronic kidney injury.”

Multiple valve replacement surgery

Chong Lei, MD, PhD, of the department of anesthesiology and perioperative medicine at Xijing Hospital of the Fourth Military Medical University in Xi’an, China, and colleagues analyzed data from 244 patients who underwent multiple valve replacement surgery.

Patients were assigned nitric oxide (n = 117) or nitrogen (n = 127) during cardiopulmonary bypass. Both groups received the assigned treatment gas at the onset of cardiopulmonary bypass for 24 hours. This time was reduced if patients were extubated early. Patients were then weaned off the treatment gases during a 2-hour period.

The primary endpoint was the incidence of acute kidney injury, defined as an increase of 0.3 mg/dL serum creatinine from baseline within 2 days after surgery or an increase of 50% within 7 days after surgery. Secondary outcomes of interest were the loss of 25% of estimated glomerular filtration rate, stage 3 chronic kidney disease and major adverse kidney events, all of which were assessed at 30, 90 and 365 days after ICU admission.

Compared with the control group, the nitric oxide group had fewer patients who developed acute kidney injury (50% vs. 64%; RR = 0.78; 95% CI, 0.62-0.97).

Advancement of kidney disease

At 90 days, patients assigned nitric oxide were less likely to develop stage 3 chronic kidney disease compared with those assigned nitrogen (21% vs. 33%; RR = 0.64; 95% CI, 0.41-0.99). This was also seen at 1 year (18% vs. 31%; RR = 0.59; 95% CI, 0.36-0.96).

Fewer major adverse kidney events occurred in the nitric oxide group vs. the control group at 30 days (RR = 0.4; 95% CI, 0.18-0.92), 90 days (RR = 0.4; 95% CI, 0.17-0.92) and 1 year (RR = 0.47; 95% CI, 0.2-1.1).

“While the results of this study cannot be generalized to all races and pathologies requiring prolonged [cardiopulmonary bypass] for cardiac surgery, this study addresses one of the most common worldwide causes of heart disease and what will likely be the most common reason globally for prolonged [cardiopulmonary bypass] in cardiac surgery for the next decades,” Lei and colleagues wrote. – by Darlene Dobkowski

Disclosures: Berra and Lei report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.