Case Presentation
64 yo diabetic male presents with gradual onset right foot pain, swelling, and drainage x1 week. On arrival, he was febrile (100.6) and tachycardic (103) but otherwise hemodynamically stable. On exam, he had a necrotic 2nd toe, non-palpable pulses, and an open wound with purulent drainage. There was questionable crepitus on exam. Subcutaneous air was noted on plain films and POCUS.
LRINEC score: 7
CRP: 50 ( >15 = +4)
WBC: 20 (15-25 = +1)
Hgb: 12.5 (11-13.5 = +1)
Sodium: 135 (> 135 = 0)
Creatinine: 1.39 (<1.6 = 0)
Glucose: 380 (>180 = +1)
POCUS clips below
Disposition:
1. IV Vanco/zosyn given
2. Immediate podiatry c/s,
3. s/p choparts amputation
4. Patient remains hospitalized
Necrotizing Soft Tissue Infections (NSTI)
1. Polymicrobial
2. Mortality 20-75%
a. Worse with delayed diagnosis
3. Types
a. Cellulitis
b. Fasciitis
c. Myositis
Risk Factors
1. IVDA
2. Uncontrolled diabetes
3. Immunocompromised
4. Elderly
5. Obesity
6. Recent surgery or trauma
7. CKD
8. Etoh abuse
9. Malnutrition
Diagnosis
1. Clinical exam
a. Findings: asymptomatic to septic shock
i. Edema, ecchymosis, hemorrhagic blisters/bullae, crepitus, necrosis
ii. Findings often late –> maintain high index of suspicion
iii. Pain out of proportion
1. Classic finding
2. Often absent
b. Missed diagnosis in over >60% of cases based on PE alone
c. *Unexplained fever –> Exam the Perineum!
2. Laboratory Values
a. Significant leukocytosis
b. Hyponatremia
c. Elevated lactate & CRP
3. LRINEC Score (Poor performance in external validation)
a. >6 Sensitivity <70%
b. >8 Sensitivity @40%
4. Imaging (Nothing is perfect!)
a. Plain films
i. Findings: soft tissue gas
ii. Sensitivity <50%, Specificity 94%
b. CT
i. Sensitivity 94.3%, Specificity 76.6%
c. Ultrasound (linear/vascular probe)
i. Findings (*compare to unaffected area):
1. Thickened subcutaneous tissue and/or fascia
2. Fluid along fascial plane
3. Subcutaneous air (similar to sonographic appearance of lung)
a. Dirty gray shadowing (see images)
b. A-lines (see images)
ii. Single Center Study with small N
1. Sensitivity 88.2%, Specificity 93.3%
2. PPV 95.4%, NPV 91.9%
iii. *Expedites the diagnosis & treatment!
Treatment
1. Resuscitation
2. IV Abx – vancomycin, zosyn, & clindamycin
3. Immediate surgical consultation
References
1. Z.S. Yen, H.P. Wang, H.M. Ma, et al. Ultrasonographic screening of clinically suspected necrotizing fasciitis. Acad Emerg Med 2012;9(12):1448-1451.
2. L. Oelze, S. Wu, & J. Carnell. Emergency ultrasonography for the early diagnosis of necrotizing fasciitis: a case series from the ED. Am J Emerg Med 2013;31(3):632-635.
3. B.W. Frazee, C. Fee, J. Lynn, et al. Community-acquired necrotizing soft tissue infections: a review of 122 cases presenting to a single emergency department over 12 years. J Emerg Med 2008;34(2):139-146.
4. M.D. Torrejón, E. Celi, D. Cancho, et al. Necrotizing myositis in a neutropenic patient: the use of ultrasound in the diagnosis of atypical presentations. Case Rep Emerg Med 2014;1-3. http://dx.doi.org/10.1155/2014/685263
5. S.M. Fernando, A. Tran, W. Cheng, et al. Necrotizing soft tissue infection: diagnostic accuracy of physical examination, imaging, and LRINEC score: a systematic review and meta-analysis. Ann Surg 2019;269(1):58-65.
6. M. Wronski, M Slodkowski, W. Cebulski et al. Necrotizing fasciitis: early sonographic diagnosis. J Clin Ultra 2011;39(4):236-239.