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Linda Le-Wendling, MD, clinical assistant professor of anesthesiology at the University of Florida and co-author of the study, said a troubling incidence of AKI in hip fracture patients—affecting as many as 67% of patients with baseline renal insufficiency—has been reported in recent trials. Perhaps not surprisingly, patients with AKI experience worse outcomes than their counterparts, including greater postoperative complications and mortality. The study was presented at the 2011 annual spring meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 57).

The study included 308 patients, aged 65 years or older, who underwent operative treatment for low-impact hip fracture at the institution between 2006 and 2008. Regional anesthesia comprised neuraxial anesthesia with conscious sedation and primarily continuous intrathecal catheters. General anesthesia was defined as inhalational or intravenous anesthesia requiring an endotracheal tube or some invasive airway device, Dr. Le-Wendling said.

When asked why clinicians chose to use intrathecal catheters instead of spinal or epidural anesthesia, Dr. Le-Wendling said that speed of analgesia and safety were the two primary concerns. “We wanted excellent, intense analgesia,” she said. “Our surgeons always want zero out of four twitches and complete muscle relaxation. And so, we didn’t figure that epidural anesthesia would allow us that.

“And with spinal anesthesia, many of our patients are frail and debilitated,” she added. Dr. Le-Wendling said that problems with hemodynamic changes can result “if you have one shot and overdo it.” The nice thing about using intrathecal catheters, she said, is being able to incrementally dose them and provide “great anesthesia” without many hemodynamic changes.

Creatinine data were gathered by reviewing each patient’s electronic record during hospitalization. These data included creatinine levels at admission, highest creatinine levels and creatinine levels at discharge. The institution’s billing database provided information on patient demographics, preoperative comorbidities and outcomes.

“Our most impressive finding was the lower incidence of acute kidney injury in the patients who had regional anesthesia [based on modified risk-factor and life-expectancy criteria],” Dr. Le-Wendling said. No patient in the regional anesthesia group had renal failure or required renal replacement therapy (compared with 2% and 3%, respectively, in the general anesthesia patients). Far fewer patients given regional anesthesia were admitted to the intensive care unit after surgery (3% vs. 11%; P=0.04).

“We also looked at their in-hospital resource utilization,” Dr. Le-Wendling said. “And there was really no significant difference in the amount of blood or blood product transfusions.” Although 4% of general anesthesia patients required transfusion, none of those in the regional group did. This difference, however, did not reach statistical significance (P=0.09).

“One of the interesting things we looked at was drug utilization, specifically the nephrotoxic agents given to patients prior to their acute kidney injury. The only difference we found was a higher incidence of [nonsteroidal anti-inflammatory drug] use in the regional group,” she said.

Patients with AKI had a higher rate of mortality than those without; this was true within the first year, and beyond. “It’s interesting to note that even though the general anesthesia group had a higher incidence of acute kidney injury, mortality was no different three years out than for regional patients,” Dr. Le-Wendling said. “This could be because patients in the regional group were a bit older. It doesn’t seem like much, but when you’re talking about 83 versus 81, age is probably working against you with regard to mortality.”

John Rowlingson, MD, professor of anesthesiology and director of the Acute Pain Center at the University of Virginia School of Medicine, in Charlottesville, who moderated the presentation, said the data were more compelling when considering the demographics of the respective patient populations. “It’s obviously very important to look at morbidity and mortality, as well as comorbidities,” Dr. Rowlingson said. “I’m impressed by the fact that the regional anesthesia folks who did better in terms of renal function were older and had a higher use of presurgery nonsteroidals.” He said those two factors “may amplify the results.”