Early data show ‘dramatic improvement’ in amputation-free survival after initiation of novel ‘Limb Alert’ for acute limb ischemia

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Charles J. Bailey

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In cases of acute limb ischemia (ALI), time is of the essence, says Charles J. Bailey, MD—from the moment a patient first reports to the emergency room (ER) through to the time of a revascularization procedure, every minute matters. Now, promising limb salvage and amputation-free survival rates emerging out of an analysis of a new “Limb Alert” system pioneered at Tampa General Hospital (TGH) Heart & Vascular Institute (HVI) have Bailey and the team behind the initiative excited at the potential for a ground-breaking advance in ALI patient care.  

For Bailey, director of both the HVI-Vascular Center of Excellence and the Limb Preservation-PAD Program at the University of South Florida (USF) in Tampa, Florida, the in-hospital and 30-day data thus far mark a significant step towards advancing what has proven a historically morbid condition.

The historical background is stark. Large studies that have plumbed Veterans Affairs1 and Medicare2 databases for temporal trends in ALI management have shown a decreasing incidence of hospital admissions and an increasing endovascular-first approach over the last two decades, but despite such trends the needle has not moved on ALI mortality outcomes out to one year, observes Bailey.

“Even with all the advancements in medical and procedural management for ALI, the observed rates of mortality, major-adverse cardiac and limb events at the in-hospital and post-discharge phases out to one year, have flatlined over the last two decades,” he says. “Endovascular therapies for ALI are less morbid, have expanded who we can treat safely, and are used with ever-increasing frequency with each new device brought to market, but that has not yet translated into improved mortality or reduced major-adverse outcomes post-discharge.”

That’s where the Limb Alert system steps in. “We have standardized the approach from patient triage up to the time of revascularization,” explains Bailey, also an assistant professor of surgery at USF. The idea is analogous to stroke or STEMI alerts in neurology or cardiac care, respectively, expediting the diagnosis and management for time-sensitive conditions. It functions through a paging system triggered by ER staff who, after triaging a patient and identifying a case of ALI, submit a hospital-wide alert to the limb salvage and peripheral arterial disease (PAD) program clinicians, ICU personnel and other key stakeholders.

Bailey points to an encouraging early dataset that suggests “a dramatic improvement in our limb salvage and amputation-free survival as compared to our pre-alert experience.”  The six-month data, starting from June 1 through Nov. 30, 2022, show that the Limb Alert system was activated 37 times, with a correct diagnosis of ALI confirmed in 28, which equates to a 76% positive prediction rate.

“Kudos for this goes to the ER staff for their clinical acumen and to the limb preservation team for all their efforts in education and planning for the launch of the alert system,” remarks Bailey. “Prospectively, we have measured different temporal phases of the alert system including time stamps from the time of triage to the initiation of the alert, time from alert to the start of heparin, time to imaging, and time to definitive procedure.

“Creating a uniform alert protocol and focusing on these temporal phases to expedite care has resulted in a 30-day limb salvage rate of 93%—26 of 28 limbs. We have had two in-hospital amputations and one person passed postoperatively due to cardiac complications. All considered, this amounts to an observed 30-day amputation-free survival rate of 89%.

“What is quite interesting here is that these numbers are much improved from what our own institutional experience had been pre-alert, and more successful than historical reports of in-hospital and 30-day amputation-free survival,” Bailey adds. “So, in short, the Limb Alert process works.”

Bailey credits the early success of the novel system to the true multidisciplinary approach at its core. “Limb Alert was developed as a collaborative effort between vascular surgery, the emergency department and our limb preservation team, including podiatry and radiology,” he says.  “After talking with colleagues in other parts of the country, there are lots of academic centers with multidisciplinary clinics to address critical limb threatening ischemia (CLTI), but very few have tried to streamline the clinical workflow for non-traumatic acute limb-threatening emergencies.”

With the system now in place and a standardized approach to ALI established, Bailey and colleagues plan to use the Limb Alert paradigm as a cornerstone for the creation of a modern, randomized controlled trial to explore the outcomes of operative and endovascular management of ALI. “This is just one move on the chessboard to gain a better insight into how we can improve the care of these patients—how we can improve the care of a condition that has historically high rates of perioperative morbidity and limb loss,” Bailey concludes.

References

  1. Andrew F Prouse, Paula Langner, Mary E Plomondon, P Michael Ho, Javier A Valle, Anna E Barón, Ehrin J Armstrong, Stephen W Waldo. Temporal trends in the management and clinical outcomes of lower extremity arterial thromboembolism within a national Veteran population. Vascular Medicine. 2019, 24(1):41–49.
  2. Donald T. Baril MD, Kaushik Ghosh PhD, Allison B. Rosen, MD, MPH, ScD. Trends in the incidence, treatment, and outcomes of acute lower extremity ischemia in the United States Medicare population. J Vasc Surg. 2014, 60:669-77.

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