Introduction:
The life-altering decision to proceed with lower extremity amputation may occur very quickly, such as when injury has resulted in critical loss of tissue /perfusion, or may proceed more slowly if the viability of the extremity remains in question. The existing literature clearly describes amputations following electrical injuries; however, little is published discussing the complicated course of burn-injured patients who underwent delayed lower extremity amputations due to non-electrical mechanisms. Co-morbid illness, pre-injury health, and infections contribute to the need for delayed amputations. The patient and family’s fear of amputation alongside provider delay in hopes of salvage may prolong time to amputation and place the patient at risk for worsening outcomes. Overall, incidence of amputation in the burn population remains low, at about 2%. Despite this number, the resulting long-term functional, emotional and socioeconomic sequelae are potentially devastating. The impact is considered alongside the risk for increased morbidity and death associated with delayed amputation. Identifying burn patients who have undergone lower extremity amputations reveals outcomes as they related to time to amputation, offering results to compare with other burn centers and to serve as a basis for future decision making.

Methods:
This single verified burn center retrospective medical records review was granted “exempt” status following review by the hospital Institutional Review Board. Adult burn – injured patients, greater than or equal to 18 years of age, admitted as an inpatient from January 1, 2010 to December 31, 2020 were identified through the center’s burn registry data using ICD (International Classification of Disease) 9 & 10 and CPT (Current Procedural Terminology) codes to identify patients who underwent any form of lower extremity amputations. Patients with non-burn related amputations and those with isolated toe or partial foot amputations related to diabetes were excluded. Demographic/Descriptive data included age, birth gender, BMI (Body Mass Index), nationality, mechanism of injury, and TBSA (total body surface area), substance, tobacco and alcohol abuse, and presence of co-morbid illness noted at admission. We assessed the association between multiple variables on day of first amputation and TBSA through linear regression, one sample t-test, and one-way ANOVA using SAS version 9.4 software (SAS Institute, Inc, Cary, North Carolina).

Findings:
Of our final study population (N= 12), all but one patient were male, with mean age 44 years old. The majority (83%) suffered flame burns, with 58% having motor vehicle collision (MVC) as mechanism of injury. Hypertension (33%) was the most common comorbidity. Half of these patients admitted to alcohol abuse, with 50% also reporting current tobacco use. Hospital day of first amputation ranged from 1-30, with a mean of day 11. Five patients did not require vasopressor therapy. For the remaining seven patients, pressor requirements ranged from 30 minutes to 500 hours total. Three patients (25%) had positive blood cultures results, two patients (16%) were documented to have positive sputum cultures, and 5 patients (42%) had positive tissue cultures harvested from the affected extremity. For every 24 total vasopressor hours, day of first amputation increases by 1 day. Acute Kidney injury (AKI) was noted in 8 patients (67%), with only one of those requiring Continuous renal replacement therapy (CRRT). An ANOVA was conducted to compare all renal impairment data points and found no significant difference between the mean difference in the day to amputation among these categories (p-value=0.18). The diagnosis and treatment of infections as demonstrated through blood, tissue or sputum cultures were detailed and analyzed. Patients with positive tissue cultures were found to have waited an average 10.17 days longer for amputation than those without. Hospital LOS ranged from 31-126 days with a mean of 54 days. There was one death and this was also the only patient positive for fusarium. Finally, 50% of the study patients were discharged to an inpatient rehabilitation facility.

Conclusions:
The hospital day of first amputation was the most impactful parameter, with longer time to first amputation associated with positive tissue cultures, mortality, vasopressor therapy and hospital length of stay. Though one limitation was our small study population size, it does appear to be consistent with that of other burn centers. Additional limitations are the retrospective nature and reliance on electronic medical record and registry data. This data provided an opportunity to review outcomes to promote reflective analysis and provided data to support earlier amputation for nonviable extremities, though additional research is clearly needed to better describe these relationships. Future analysis of burn-injured patients who suffer lower extremity amputations should consider additional outcomes to include quality of life and return to work.