Chance to cut: defining a negative exploration rate in patients with suspected necrotizing soft tissue infection

Erin C Howell; Jessica A Keeley; Amy H Kaji; Molly R Deane; Dennis Y Kim; Brant Putnam; Steven L Lee; Alexis L Woods; Angela L Neville

doi:10.1136/tsaco-2018-000264

Chance to cut: defining a negative exploration rate in patients with suspected necrotizing soft tissue infection

Trauma Surg Acute Care Open. 2019 Feb 27;4(1):e000264. doi: 10.1136/tsaco-2018-000264. eCollection 2019.

Authors

Erin C Howell¹, Jessica A Keeley², Amy H Kaji³, Molly R Deane¹, Dennis Y Kim¹, Brant Putnam¹, Steven L Lee⁴, Alexis L Woods⁵, Angela L Neville¹

Affiliations

¹ Department of Surgery, Harbor-UCLA Medical Center, Torrance, California, USA.
² Department of Surgery, University of California, San Francisco East Bay, Oakland, California, USA.
³ Department of Emergency Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.
⁴ Division of Pediatric Surgery, UCLA Mattel Children's Hospital, Los Angeles, California, USA.
⁵ David Geffen School of Medicine at UCLA, Los Angeles, California, USA.

Abstract

Background: Necrotizing soft tissue infections (NSTI) are aggressive infections associated with significant morbidity and mortality. Despite multiple predictive models for the identification of NSTI, a subset of patients will not have an NSTI at the time of surgical exploration. We hypothesized there is a subset of patients without NSTI who are clinically indistinguishable from those with NSTI. We aimed to characterize the differences between NSTI and non-NSTI patients and describe a negative exploration rate for this disease process.

Methods: We conducted a retrospective review of adult patients undergoing surgical exploration for suspected NSTI at our county-funded, academic-affiliated medical center between 2008 and 2015. Patients were identified as having NSTI or not (non-NSTI) based on surgical findings at the initial operation. Pathology reports were reviewed to confirm diagnosis. The NSTI and non-NSTI patients were compared using χ² test, Fisher's exact test, and Wilcoxon rank-sum test as appropriate. A p value <0.05 was considered significant.

Results: Of 295 patients undergoing operation for suspected NSTI, 232 (79%) were diagnosed with NSTI at the initial operation and 63 (21%) were not. Of these 63 patients, 5 (7.9%) had an abscess and 58 (92%) had cellulitis resulting in a total of 237 patients (80%) with a surgical disease process. Patients with NSTI had higher white cell counts (18.5 vs. 14.9 k/mm³, p=0.02) and glucose levels (244 vs. 114 mg/dL, p<0.0001), but lower sodium values (130 vs. 134 mmol/L, p≤0.0001) and less violaceous skin changes (9.2% vs. 23.8%, p=0.004). Eight patients (14%) initially diagnosed with cellulitis had an NSTI diagnosed on return to the operating room for failure to improve.

Conclusions: Clinical differences between NSTI and non-NSTI patients are subtle. We found a 20% negative exploration rate for suspected NSTI. Close postoperative attention to this cohort is warranted as a small subset may progress.

Level of evidence: Retrospective cohort study, level III.

Keywords: debridement; diagnosis; necrotizing fasciitis; necrotizing soft tissue infections; negative exploration.