Necrotizing fasciitis
Background
- A rare, rapidly progressive infection primarily involving the fascia and subcutaneous tissue
- Most severe form of soft tissue infection and potentially limb and life threatening
- Early recognition and aggressive debridement are major prognostic determinants and delay increases mortality[1]
Risk Factors
- DM
- Drug use
- Obesity
- Immunosuppression
- Recent surgery
- Traumatic wounds
Clinical Features
- Skin exam
- Erythema (without sharp margins)
- Exquisitely tender (pain out of proportion to exam)
- Skip lesions
- Hemorrhagic bullae (violaceous bullae)
- May be preceded by skin anesthesia (destruction of superficial nerves)
- Crepitus (in type I infections)
- Swelling/edema may produce compartment syndrome
- Constitutional
- Fever
- Tachycardia
- Systemic toxicity
Differential Diagnosis
Skin and Soft Tissue Infection
- Cellulitis
- Erysipelas
- Lymphangitis
- Folliculitis
- Hidradenitis suppurativa
- Skin abscess
- Necrotizing soft tissue infections
- Mycobacterium marinum
Look-A-Likes
- Sporotrichosis
- Osteomyelitis
- Deep venous thrombosis
- Pyomyositis
- Purple glove syndrome
- Tuberculosis (tuberculous inflammation of the skin)
Diagnosis
Work-Up
- CBC
- Chem
- PT/PTT/INR
- CK
- Lactate
Evaluation
- Surgical exploration is the ONLY way to definitively establish the diagnosis of necrotizing infection
- Imaging
- Should not delay surgical exploration
- CT is study of choice
HUCLA NF vs Non-NF Criteria (Wall et al)
- Retrospective study discovered:[2]
- WBC count >15.4(x103/mm3) OR Na <135(mmol/L)
- Associated with NF and combo of both increased likelihood of NF
- PPV 26%/NPV 99%
- Useful tool to rule out NF, not a good tool for confirming presence of NF
- Helps distinguish NF from non-NF infection, when classic 'hard' signs of NF are absent however clinical judgment should still be used in patient with high suspicion of the disease
Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) Score (Wong et al)
Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) Score[3]
Has not been prospectively validated, index of suspicion is key and 10% of the patients with a score < 6 had Necrotizing Fasciitis. A score > 6 has PPV of 92% and NPV of 96% for necrotizing fasciitis.
- CRP (mg/L) ≥150: 4 points
- WBC count (×103/mm3)
- <15: 0 points
- 15–25: 1 point
- >25: 2 points
- Hemoglobin (g/dL)
- >13.5: 0 points
- 11–13.5: 1 point
- <11: 2 points
- Sodium (mmol/L) <135: 2 points
- Creatinine (umol/L) >141: 2 points
- Glucose >180 mg/dL (10 mmol/L): 1 point
Grouping by Scores
- Low Risk: score 5 (10% of pts with score < 6 still had nec fasc)
- Moderate Risk: score 6– 7
- High Risk: score >8
Treatment
- Surgical exploration and debridement is both the definitive diagnostic modality and the definitive treatment
- Indicated in setting of severe pain, toxicity, fever, elevated CK (w/ or w/o radiographic evidence)
- Antibiotics
- Must cover Gram +/- and anaerobes (esp GAS and clostridium)
- Piperacillin-Tazobactam 3.375-4.5g q6hr AND clindamycin 600-900mg q8hr AND vancomycin 1gm IV q12hr
- Diabetics
- IVFs and IV Insulin (with high POCT glucose) for glycemic control (after paging surgery)
Disposition
- Admit/OR
See Also
References
- ↑ Wong CH, Khin LW, Heng KS, Tan KC, Low CO (2004). "The LRINEC Laboratory Rother soft tissue infections". Critical Care Medicine 32 (7): 1535–1541. doi:10.1097/01.CCM.0000129486.35458.7D. PMID 15241098
- ↑ Wall DB et al. A simple model to help distinguish necrotizing fasciitis from nonnecrotizing soft tissue infection. J Am Coll Surg. 2000 Sep;191(3):227-31.
- ↑ Wong C. "The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections". Crit Care Med. 2004. 32(7):1535-41.