Real-time identification of life-threatening necrotizing soft-tissue infections using indocyanine green fluorescence imaging.

Significance: Necrotizing soft-tissue infections (NSTIs) are life-threatening infections with a cumulative case fatality rate of 21%. The initial presentation of an NSTI is non-specific, frequently leading to misdiagnosis and delays in care. No current strategies yield an accurate, real-time diagnosis of an NSTI. Aim: A first-in-kind, observational, clinical pilot study tested the hypothesis that measurable fluorescence signal voids occur in NSTI-affected tissues following intravenous administration and imaging of perfusion-based indocyanine green (ICG) fluorescence. This hypothesis is based on the established knowledge that NSTI is associated with local microvascular thrombosis. Approach: Adult patients presenting to the Emergency Department of a tertiary care medical center at high risk for NSTI were prospectively enrolled and imaged with a commercial fluorescence imager. Single-frame fluorescence snapshot and first-pass perfusion kinetic parameters-ingress slope (IS), time-to-peak (TTP) intensity, and maximum fluorescence intensity (IMAX)-were quantified using a dynamic contrast-enhanced fluorescence imaging technique. Clinical variables (comorbidities, blood laboratory values), fluorescence parameters, and fluorescence signal-to-background ratios (SBRs) were compared to final infection diagnosis. Results: Fourteen patients were enrolled and imaged (six NSTI, six cellulitis, one diabetes mellitus-associated gangrene, and one osteomyelitis). Clinical variables demonstrated no statistically significant differences between NSTI and non-NSTI patient groups (p-value≥0.22). All NSTI cases exhibited prominent fluorescence signal voids in affected tissues, including tissue features not visible to the naked eye. All cellulitis cases exhibited a hyperemic response with increased fluorescence and no distinct signal voids. Median lesion-to-background tissue SBRs based on snapshot, IS, TTP, and IMAX parameter maps ranged from 3.2 to 9.1, 2.2 to 33.8, 1.0 to 7.5, and 1.5 to 12.7, respectively, for the NSTI patient group. All fluorescence parameters except TTP demonstrated statistically significant differences between NSTI and cellulitis patient groups (p-value<0.05). Conclusions: Real-time, accurate discrimination of NSTIs compared with non-necrotizing infections may be possible with perfusion-based ICG fluorescence imaging.

Ultrasonography for Skin and Soft Tissue Infections, Noninfectious Cysts, Foreign Bodies, and Burns in the Critical Care Setting.

There are multiple opportunities for the use of ultrasonography in the diagnosis of skin and soft tissue differentials. Ultrasonography is inexpensive, easily reproducible, and able to provide real-time data in situations where condition changes and progression are common. Not only does bedside ultrasonography provide the clinician an in-depth look beyond epidermal structures into body cavities, it remains a safe, nonionizing radiating, effective, cost-efficient, reliable, and accessible tool for the emergency management of life- and limb-threatening integumentary infections. Unnecessary invasive procedures are minimized, providing improved patient outcomes. Integumentary abnormalities secondary to trauma, surgery, and hospitalization are common among critical care patients. This article provides a brief overview and evidence-based recommendations for the use of ultrasonography in the critical care setting for integumentary system conditions, including common skin and soft tissue differentials, foreign bodies, and burn depth assessment.

Emphysematous Osteomyelitis of the Pubis Associated With Necrotizing Soft Tissue Infection of the Thigh.

Emphysematous osteomyelitis (EO) is a rare condition identified through the presence of intraosseous gas. It is frequently fatal even with prompt recognition and management. We report a case of EO presenting with a necrotizing soft tissue infection of the thigh in the setting of prior pelvic radiation. The purpose of this study was to highlight the unusual association between EO and necrotizing soft tissue infection.

Spectrum of imaging findings in soft-tissue necrosis.

Soft tissue necrosis can occur at different tissue levels, with numerous underlying causes. In this pictorial review, we highlight myonecrosis, and its accompanying stages, fat necrosis, devitalized soft tissue seen with infection, and necrotizing soft tissue infections. Imaging examples are provided with each entity.

CT utilization in evaluation of skin and soft tissue extremity infections in the ED: Retrospective cohort study.

OBJECTIVE: Skin and soft tissue infections (SSTI) are commonly diagnosed in the emergency department (ED). While most SSTI are diagnosed with patient history and physical exam alone, ED clinicians may order CT imaging when they suspect more serious or complicated infections. Patients who inject drugs are thought to be at higher risk for complications from SSTI and may undergo CT imaging more frequently. The objective of this study is to characterize CT utilization when evaluating for SSTI in ED patients particularly in patients with intravenous drug use (IVDU), the frequency of significant and actionable findings from CT imaging, and its impact on subsequent management and ED operations. METHODS: We performed a retrospective analysis of encounters involving a diagnosis of SSTI in seven EDs across an integrated health system between October 2019 and October 2021. Descriptive statistics were used to assess overall trends, compare CT utilization frequencies, actionable imaging findings, and surgical intervention between patients who inject drugs and those who do not. Multivariable logistic regression was used to analyze patient factors associated with higher likelihood of CT imaging. RESULTS: There were 4833 ED encounters with an ICD-10 diagnosis of SSTI during the study period, of which 6% involved a documented history of IVDU and 30% resulted in admission. 7% (315/4833) of patients received CT imaging, and 22% (70/315) of CTs demonstrated evidence of possible deep space or necrotizing infections. Patients with history of IVDU were more likely than patients without IVDU to receive a CT scan (18% vs 6%), have a CT scan with findings suspicious for deep-space or necrotizing infection (4% vs 1%), and undergo surgical drainage in the operating room within 48 h of arrival (5% vs 2%). Male sex, abnormal vital signs, and history of IVDU were each associated with higher likelihood of CT utilization. Encounters involving CT scans had longer median times to ED disposition than those without CT scans, regardless of whether these encounters resulted in admission (9.0 vs 5.5 h), ED observation (5.5 vs 4.1 h), or discharge (6.8 vs 2.9 h). DISCUSSION: ED clinicians ordered CT scans in 7% of encounters when evaluating for SSTI, most frequently in patients with abnormal vital signs or a history of IV drug use. Patients with a history of IVDU had higher rates of CT findings suspicious for deep space infections or necrotizing infections and higher rates of incision and drainage procedures in the OR. While CT scans significantly extended time spent in the ED for patients, this appeared justified by the high rate of actionable findings found on imaging, particularly for patients with a history of IVDU.

Imaging of Soft Tissue Infections.

Although superficial infections can often be diagnosed and managed clinically, physical examination may lack sensitivity and specificity, and imaging is often required to evaluate the depth of involvement and identify complications. Depending on the area of involvement, radiography, ultrasound, CT, MR imaging, or a combination of imaging modalities may be required. Soft tissue infections can be nonnecrotizing or necrotizing, with the later having a morbid and rapid course. Infectious tenosynovitis most commonly affects the flexor tendon sheaths of the hand, characterized by thickened and enhancing synovium with fluid-filled tendon sheaths.

POINT-OF-CARE ULTRASOUND IN THE EARLY DIAGNOSIS OF NECROTIZING FASCIITIS.

OBJECTIVE: The aim: To detect the ultrasonographic signs of necrotizing fasciitis (NF) suitable for its early diagnosis. PATIENTS AND METHODS: Materials and methods: Eigty two patients with soft tissue infection, including 14 with necrotizing faciitis, were examined by ultrasonography at the admission. Ultrasonografic features were compared to intraoperative findings by the same surgeon. RESULTS: Results: The thickening of subcutaneous tissue had high sensitivity (100%), but low specificity (5.8%). The hypoechoic and hyperechoic zones had the shape of "cobblestone" with sensitivity - 78.5%, specificity - 33.8%. Higher specificity (69.1%) had sign of "cobblestone separation" on two layers. The presence of fluid above the fascia (sensitivity - 71.4%; specificity - 69.1%), thickening of the fascia (sensitivity - 85.7%; specificity - 58.8%), indistinctness of the fascia edges (sensitivity - 85.7%; specificity - 66.1%) and loss of fascial homogeneity (sensitivity - 71.4%, specificity - 66.1%) were noted in early stages of NF. Advanced cases of NF were accompanied by the dissection of thick¬ened fascia with a strip of fluid (sensitivity - 57.1%, specificity - 92.6%) and accumulation of a fluid under the fascia (sensitivity - 28.5%, specificity - 95.5%). The muscles thickening (sensitivity - 28.5%; specificity - 67.6%), skin thickening (sensitivity - 57.1%; specificity - 58.8%), and loss of the skin's lower edge clarity (sensitivity - 57.1%; specificity - 63.2%) don't have diagnostic value without other signs of NF. CONCLUSION: Conclusions: Point-of-care ultrasonography allows visualization of soft tissue changes that may be hidden in the initial stages of necrotizing fasciitis and should be recommended for implementation as mandatory method of examination in patients with suspected surgical soft tissue infection.

ACR Appropriateness Criteria® Suspected Osteomyelitis, Septic Arthritis, or Soft Tissue Infection (Excluding Spine and Diabetic Foot): 2022 Update.

Musculoskeletal infections involve bones, joints, and soft tissues. These infections are a common clinical scenario in both outpatient and emergent settings. Although radiography provides baseline findings, a multimodality approach is often implemented to provide more detailed information on the extent of infection involvement and complications. MRI with intravenous contrast is excellent for the evaluation of musculoskeletal infections and is the most sensitive for diagnosing osteomyelitis. MRI, CT, and ultrasound can be useful for joint and soft tissue infections. When MRI or CT is contraindicated, bone scans and the appropriate utilization of other nuclear medicine scans can be implemented for aiding in the diagnostic imaging of infection, especially with metal hardware and arthroplasty artifacts on MRI and CT. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Diagnostic performance of MRI and CT in diagnosing necrotizing soft tissue infection: a systematic review.

OBJECTIVE: To systematically review the accuracy of MRI and CT in diagnosing necrotizing soft tissue infection (NSTI). METHODS: MEDLINE and Embase were searched for original studies which reported the diagnostic performance of MRI or CT in detecting NSTI. Individual study quality was assessed using the QUADAS-2 tool. Sensitivity and specificity of MRI and CT were calculated and, if supported by data from at least two studies, pooled using a bivariate random-effects model. RESULTS: Six MRI studies and 7 CT studies were included. There were no major concerns with regard to study quality and applicability. The included studies used multiple diagnostic criteria, with sensitivities and specificities of both MRI and CT ranging between 0 and 100%. T2 hyperintensity of deep fascia was the most commonly used diagnostic MRI criterion (5 studies), yielding a pooled sensitivity of 86.4% (95% confidence interval [CI] 76.1-92.7%) and a pooled specificity of 65.2% (95% CI 35.4-86.6%). Presence of gas was the most commonly used diagnostic CT criterion (3 studies), yielding a pooled sensitivity of 48.6% (95% CI 37.1-60.2%) and a pooled specificity of 93.2% (95% CI 73.3-98.5%). CONCLUSION: T2 hyperintensity of deep fascia at MRI has high sensitivity and moderate specificity in diagnosing NSTI. Presence of gas at CT has low sensitivity but high specificity. A combination of diagnostic criteria may improve diagnostic performance, but this needs further investigation.

Anatomic and Treatment Descriptive Features of Foot Infections Presenting With Radiographic Soft Tissue Emphysema.

Foot infections associated with soft tissue emphysema, or the radiographic appearance of gas, are widely considered to necessitate urgent decompression with excisional debridement of the necrotic and infectious tissue burden. The objective of this investigation was to describe anatomic features and clinical outcomes associated with the presence of soft tissue emphysema in foot infections. A retrospective chart review was performed of 62 subjects meeting selection criteria. These were primarily male (74.2%), with a history of diabetes mellitus (85.5%), and without a history of previous lower extremity revascularization (98.4%). The primary radiographic location of the soft tissue emphysema was most frequently in the forefoot (61.3%), followed by the midfoot (21.0%), and rearfoot (16.1%). The soft tissue emphysema was most frequently observed primarily in the dorsal foot tissue (49.2%), followed by both dorsal and plantar foot tissue (27.4%), and the plantar foot tissue (24.2%). The soft tissue emphysema was confined to the primary anatomic location in 74.2% of subjects, while 25.8% of cases demonstrated extension into a more proximal anatomic area. Eighty-two percent of subjects underwent a bedside incision and drainage procedure on presentation in the emergency department, and 95.2% underwent a formal incision and drainage procedure in the operating room at 1.05 ± 0.79 (0-5) postadmission days. Twenty-seven percent of subjects had an unplanned 30-day readmission and 17.7% underwent an unplanned reoperation within 30 days following the index discharge. Fifty-two percent of subjects underwent a minor or major amputation during the index admission, while 33.9% eventually resulted in major limb amputation within 12 months. We hope that this investigation adds to the body of knowledge and provides expectations with respect to the evaluation and treatment of foot soft tissue infections complicated by the presence of radiographic soft tissue emphysema.

Role of point-of-care ultrasound (POCUS) in the diagnosis of an abscess in paediatric skin and soft tissue infections: a systematic review and meta-analysis.

AIMS: To evaluate the effect of point-of-care ultrasound (POCUS) for the diagnosis of an abscess and to compare the diagnostic accuracy of POCUS and physical examination (PE) in paediatric patients with skin and soft tissue infections (SSTI) in the emergency department. MATERIAL AND METHODS: A comprehensive literature search was carried out to identify Englishlanguage studies on POCUS for differentiating an abscess from cellulitis in paediatric patients with SSTI. The quality of the study was assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 tool, and pooled sensitivity and specificity of various POCUS findings were determined. RESULTS: Seven studies with a total of 870 patients were included. There was significant heterogeneity across the included studies. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio for the diagnosis of abscess by POCUS were 0.90 (95% confidence interval [CI], 0.82-0.95), 0.80 (95% CI, 0.72-0.86), 4.5 (95% CI, 3.1-6.4), 0.13 (95% CI, 0.07-0.23), and 36 (95% CI, 17-75), respectively, with an area under the curve (AUC) was 0.89 (95% CI, 0.86-0.91). Four studies provided data regarding the PE method. The pooled sensitivity, specificity, and AUC of PE for the abscess were 0.84 (95% CI, 0.80-0.88), 0.69 (95% CI, 0.62-0.76), and 0.85 (95% CI, 0.81-0.88). CONCLUSIONS: POCUS is useful in identifying abscesses in paediatric patients with SSTI in emergency department, especially when PE is equivocal and outperforms PE alone.

Soft tissue masses of the epitrochlear region.

The epitrochlear lymph nodes (ELN) are rarely examined clinically and are difficult to identify radiologically in healthy patients. They are, therefore, generally under appreciated as a source of significant pathology. Despite this, enlargement of an ELN is almost always secondary to a pathological process, the differential for which is relatively narrow. The following pictorial review illustrates the spectrum of infectious, inflammatory and malignant conditions affecting the ELN, some of which are quite specific to this location. We also emphasise the importance of distinguishing enlarged ELNs from benign and malignant non-nodal soft tissue masses, which can have very similar clinical presentation and imaging appearances.

Necrotising soft tissue infection in western Sydney: An 8-year experience.

BACKGROUND: This study aimed to assess the risk factors, management, imaging validity, Laboratory Risk Indicator for Necrotising infection (LRINEC) score and outcomes of necrotising soft tissue infection (NSTI) at a western Sydney tertiary hospital. METHODS: A retrospective study was conducted of all patients with NSTI from 2012 to 2019 at our institution. Patient characteristics, imaging, microbiology and site, LRINEC score, surgical management and outcomes/disposition were collected. RESULTS: Thirty-six patients met the inclusion criteria with mean age of 52 years and body mass index of 38.1; 55.6% were male, 48% of Polynesian descent and 55.6% were diabetic. The most frequent sites of NSTI were perineal (30.6%), lower limb (30.6%), perianal (19.3%) and trunk (11.1%). A total of 64% of patients underwent computed tomography radiological imaging with diagnostic accuracy of 50%. The mean LRINEC score was 7 (1-20). A total of 52.8% were transferred from another facility or non-surgical teams which delayed surgical review by 11.4 h (P < 0.03) and operating time by 12.4 h (P < 0.04) compared with direct emergency department referrals to the on-call surgical team. There was no statistical difference in outcomes in both groups. The overall average time to surgical debridement was 16.2 h (standard deviation 19.6, range 3.4-105.1). The mean hospital length of stay was 20.9 days; 44.4% of patients were transferred for rehabilitation or plastic reconstruction with a single mortality from multi-organ failure. CONCLUSION: The optimal management of NSTI requires a high index of suspicion and LRINEC score is a useful adjunct in aiding a clinician's decision. Early surgical debridement within 24 h of diagnosis and a multidisciplinary approach is associated with a lower mortality rate.

CT in necrotizing soft tissue infection: diagnostic criteria and comparison with LRINEC score.

OBJECTIVE: To investigate which computed tomography (CT) criteria are most useful in diagnosing necrotizing soft tissue infection (NSTI) and how CT performs with respect to the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score. METHODS: Patients who underwent CT for suspected NSTI were eligible for inclusion. LRINEC score was assessed. CT scans were evaluated for subcutaneous edema, fluid along superficial fascia, fluid along deep fascia, blurring of intermuscular fat planes, fluid collection, and air in the soft tissues. Surgical findings or clinical follow-up served as reference standard. RESULTS: Fourteen patients with NSTI and 34 patients with non-NSTI were included. LRINEC score was significantly higher in patients with NSTI (median of 7.5 vs. 6, p = 0.039). Fluid along the deep fascia was significantly more frequently present in patients with NSTI (46.2% vs. 5.9%, p = 0.001). In multiple logistic regression analysis, presence of fluid along the deep fascia was significantly associated with NSTI (odds ratio [OR] = 10.28, 95% CI: 1.57 to 67.18, p = 0.015), whereas the LRINEC score was not significantly associated with NSTI (OR = 1.27, 95% CI: 0.92 to 1.74, p = 0.146). Using presence of fluid along the deep fascia as diagnostic criterion for NSTI, sensitivity was 46.2% (95% CI, 23.2 to 70.9%) and specificity was 94.1% (95% CI, 80.9 to 98.4%). CONCLUSION: Fluid along the deep fascia was the only CT criterion which was significantly associated with NSTI and appeared more useful than the LRINEC score. In the right clinical setting, presence of this CT finding is highly suggestive for NSTI. Its absence, however, does not rule out NSTI. KEY POINTS: • The presence of fluid along the deep fascia at CT is highly suggestive for NSTI in suspected patients. Its absence, however, does not rule out NSTI. `• The use of fluid along the deep fascia as a criterion appears to be more useful than the LRINEC score in diagnosing NSTI.

Iatrogenic subcutaneous emphysema in aesthetic breast augmentation Medicolegal aspects.

The aim of the present study was to investigate clinical results and medico-legal aspects related to the surgical procedure of mini breast augmentation. In the present case, a 28-year-old young woman with bilateral mammary hypoplasia underwent surgery, under local anesthesia, with the placement of 150 cc breast implants in the sub-glandular plane. We report a case of dramatic isolated subcutaneous emphysema without pneumothorax and pneumomediastinum to be related in terms of a causal link to the surgical procedure which the patient underwent. The plastic surgeon proceeded to replace a breast implant that presumably, represented the vehicle of transmission of the suspected pathogen responsible for the infection, to become a causal role for the infectious manifestation. This case report is an emblematic example of the need for a careful and correct surgical procedure, in order to avoid serious consequences as in the case in question, burdened by the occurrence of unsafe conditions for the patient. Compliance with the guidelines and the technical datasheet of breast implants is essential in order to avoid the concrete hypothesis of professional liability. KEY WORDS: Aesthetic breast augmentation, Breast implant, Iatrogenic subcutaneous emphysema.

Point of Care Ultrasound Use by Associate Providers for Differentiating Abscess Versus Cellulitis Skin and Soft Tissue Infection in the Emergency Department.

BACKGROUND: Skin and soft tissue infections (SSTIs) are a common complaint in the ambulatory setting and pose a significant burden on the health care system. OBJECTIVES: We sought to determine the accuracy of ultrasound for detecting soft tissue abscesses by emergency medicine associate providers (APs). METHODS: This was a prospective observational study of adult patients with suspected SSTI in the emergency department of a rural tertiary care academic medical center. The AP performed and interpreted point-of-care ultrasound (POCUS) of the suspected infected area. Ultrasound images and interpretation were reviewed by the attending emergency physician with either rejection or agreement of the image interpretation, diagnosis, and management. If incision and drainage was performed, presence or absence of purulent drainage was recorded. RESULTS: Sixty-four patients with suspected SSTI were enrolled: 29 had POCUS-proven abscesses and 33 had cellulitis; 2 were excluded. AP clinical evaluation alone for identifying abscess revealed sensitivity of 92.3 (74.9-99.1), specificity of 67.7 (49.5-82.6), positive predictive value of 68.6 (57.0-78.2), and negative predictive value of 92.0 (81.4-100). The use of POCUS by APs in addition to clinical examination demonstrated sensitivity of 96.2 (80.4-99.9), specificity of 93.9 (79.8-99.3), positive predictive value of 92.6 (76.5-98.0), and negative predictive value of 96.9 (81.9-99.5). p values were <0.05 for test characteristics. Ultrasound results changed SSTI management decisions in 10 of 62 (16.1%) patients, with the most common change being a new incision and drainage or needle aspiration. Agreement of the POCUS interpretation between APs and attending physicians was 96.8% with a κ of 0.94 (0.85-1.00). CONCLUSION: With modest training, APs can successfully use POCUS to identify abscesses in patients in the emergency department with SSTIs. POCUS increases the ability to rule in the diagnosis and changes management in a clinically relevant number of patients with SSTIs.

Point-of-Care Ultrasound Used to Distinguish Between Superficial Skin Abscess and Deep Mediastinal Abscess: A Case Report.

BACKGROUND: Skin and soft tissue infections (SSTIs) are an increasingly common complaint in the emergency department (ED), but physical examination does not reliably identify abscesses or accurately determine which skin lesions require incision and drainage. Point-of-care ultrasound (POCUS) improves management of soft tissue skin infections by detecting occult abscess, preventing unnecessary procedures, and identifying more complex disease requiring further imaging. CASE REPORT: Here, we report a case in which POCUS drastically changed the management of what initially appeared to be an uncomplicated superficial skin abscess but was actually a much more serious mediastinal infection. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case underscores the importance and utility of POCUS to enhance the physical examination in suspected SSTIs. Because POCUS is easy, accurate, low risk, and can change management, we recommend its consideration as a standard component of the ED work up for SSTIs.