View source for Necrotizing fasciitis

==Background==
*A rapidly progressive infection primarily involving the fascia and subcutaneous tissue
*Formerly a rare diagnosis, frequency has risen due to an increase in immunocompromised patients with significant risk factors<ref>Hakkarainen TW et al. Necrotizing soft tissue infections: review and current concepts in treatment, systems of care, and outcomes. Curr Probl Surg. 2014 Aug. 51 (8):344-72.</ref>
*Gas-formation is NOT a requirement for diagnosis, and radiographical lack of the classically taught gas formation should NEVER rule out necrotizing infection<ref>Misiakos EP et al. Current concepts in the management of necrotizing fasciitis. Front Surg. 2014. 1:36.</ref>
*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<ref>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</ref>

===Categories===
*Type I, polymicrobial
*Type II, [[group A streptococcal]]
*Type III, gas gangrene or [[clostridial]] myonecrosis

===Risk Factors===
*[[DM]]
*Drug use
*Obesity
*Immunosuppression
*Recent surgery
*Traumatic wounds

==Clinical Features==
[[File:NectrotizingFasciitis.jpeg|thumb|Nectrotizing fasciitis]]
*Skin exam
**Erythema (without sharp margins)
**Exquisitely tender (pain out of proportion to exam)
***Caveat - some patients present with "la belle indifference"
***May be a result of ischemic, insensate tissue<ref>TheHealthScience. Emergent Management of Necrotizing Soft Tissue Skin Infections. Nov 22, 2013. https://thehealthscience.com/topics/emergent-management-necrotizing-soft-tissue-skin-infections.</ref>
**Skip lesions
**Hemorrhagic bullae (violaceous bullae)
***May be preceded by skin anesthesia (destruction of superficial nerves)
**Crepitus (in type I infections)
**Lymphangitis and lymphadenopathy are absent in necrotizing fasciitis alone<ref>Seal DV. Necrotizing fasciitis. Curr Opin Infect Dis. 2001;14(2):127–32.</ref><ref>Golger A, Ching S, Goldsmith CH, Pennie RA, Bain JR. Mortality in patients with necrotizing fasciitis. Plast Reconstr Surg. 2007;119(6):1803–7.</ref>
***Lymphangitis is seen in [[cellulitis]]
***Fascia has no lymph drainage
*Swelling/edema may produce compartment syndrome
*Constitutional or toxic shock-like syndrome<ref>Puvanendran R et al. Necrotizing fasciitis. Can Fam Physician. 2009 Oct; 55(10): 981–987.</ref>
**Fever
**Tachycardia
**Systemic toxicity, [[sepsis]]
**[[Conjunctivitis]]

==Differential Diagnosis==
{{SSTI DDX}}
{{Necrotizing Rashes DDX}}

==Evaluation==
[[File:CTNecrotizingFasciitis.png|thumb|CT of necrotizing fasciitis]]
===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 - soft tissue gas, edema and fluid collections, fascial thickening with fat stranding
**US may show thickened fascial planes, fluid between fascial planes, irregularity of the fascia, subcutaneous emphysema. The study may be limited by soft tissue gas. Video lecture<ref>Soft Tissue Ultrasound with Jacob Avila on Core Ultrasound. https://www.coreultrasound.com/sti/</ref>.
**MRI - T2 subcutaneous, intramuscular, and fascial edema
*Absence of gas on imaging '''does not''' exclude diagnosis, as gas may be occult and/or certain organisms do not classically produce gas (i.e. [[Streptococcus|Group A Strep]])
{{LRINEC SCORE}}

===HUCLA NF vs Non-NF Criteria:<ref>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.</ref>===
*Retrospective study discovered:
**'''WBC count''' '''>15.4'''(x10<sup>3</sup>/mm<sup>3</sup>) 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

==Management==
*Surgical exploration and debridement is both the definitive diagnostic modality and the definitive treatment
**Indicated in setting of severe pain, toxicity, fever, elevated CK (with or without radiographic evidence)
*[[Antibiotics]]
**Must cover [[gram positives]], [[gram negatives]], and [[anaerobes]] (especially [[GAS]] and [[clostridium]])
**[[Piperacillin-Tazobactam]] 3.375-4.5g q6hr AND [[clindamycin]] 600-900mg q8hr AND [[vancomycin]] 1gm IV q12hr (consider weight base dosing of 20 mg/kg)
**[[Piperacillin-Tazobactam]] 3.375-4.5g q6hr and [[linezolid]] 600mg q12hr is an alternative regimen<ref>Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America [published correction appears in Clin Infect Dis. 2015 May 1;60(9):1448. Dosage error in article text]. Clin Infect Dis. 2014;59(2):e10-e52. doi:10.1093/cid/ciu444</ref>
*In diabetics, maintain strict glycemic control (with [[IVFs]] and IV [[insulin]] if necessary)

==Disposition==
*Admit to ICU

==See Also==
*[[Necrotizing soft tissue infections]]
*[[LRINEC_score|Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) Score]]
*[[EBQ:LRINEC Score]]

==References==
<references/>

[[Category:ID]]