Can Fluid Accumulation on Ultrasound Diagnose Necrotizing Fasciitis?

necrotizing fasciitis

Background

Necrotizing fasciitis (NF) is rapidly progressing, severe soft tissue infection with a mortality rate of 19.3% with treatment and significantly higher without treatment (1). Early diagnosis is essential to prompt surgical intervention and reduce morbidity and mortality. However, treatment can often be delayed because no laboratory or imaging test can definitively diagnose NF. Contrast-enhanced CT shows the best accuracy, but again is not perfect and can be difficult to obtain in unstable patients. MRI is similarly accurate, but even less feasible in the Emergency Department. Ultimately, it remains a surgical diagnosis.

Ultrasonography is a rapid, bedside, and non-invasive tool that has potential to accelerate assessment of patient with clinical suspicion for NF. There are ultrasonographic findings associated with NF diagnosis, including irregularity or thickening of deep fascia, subcutaneous emphysema, and fluid accumulation along the deep fascial plane (2-13). Considering this condition’s rapid progression, ultrasonography may enable physicians to quickly gauge disease severity and triage accordingly, prompting earlier surgery and bettering patient outcomes.

The Relationship Between Fluid Accumulation in Ultrasonography and Diagnosis and Prognosis of Patients with Necrotizing Fasciitis

 

Clinical Question

What is the relationship between ultrasonographic finding of fluid accumulation along the deep fascia and diagnosis and prognosis of necrotizing fasciitis?

What ultrasonographic findings are significantly different between NF patients and non-NF patients?

What is the ultrasonographic-detected depth of fluid accumulation along the deep fascia that offers the greatest accuracy to diagnosis of NF?

Is there a difference in the prognosis between NF patients with fluid accumulation compared to NF patients without fluid accumulation? 

Methods & Study Design

• Design 

Retrospective study with prospective enrollment

• Population 

This study was conducted at Chang Gung Memorial Hospital, a suburban academic tertiary care hospital.

Inclusion criteria: patients who visited the ED from February 2015 – November 2016 with clinical suspicion of NF of limbs based on symptoms and clinical signs (severe pain out of proportion, skin findings, rapid progression, crepitus, skin bullae, necrosis, or ecchymosis).

NF group: discharge diagnosis of NF, confirmed by pathology report showing necrosis after surgical intervention

Non-NF group: did not have surgical intervention or whose pathology report did not support NF diagnosis

Exclusion criteria: patients with ED visits between 24:00 – 7:00, non-lesion side also has fluid accumulation, age <18yo, prior antibiotics or debridement, lesions involving trunk area

• Intervention 

Ultrasonographic exam within 1 hour after ED arrival completed by one of three experienced emergency physicians who received an 8-hour basic and soft-tissue ultrasonographic training before the study

Orthopedic consult for surgical opinion

• Outcomes  

  • Diagnostic markers: irregularity or thickening of deep fascia, fluid accumulation, subcutaneous emphysema, subcutaneous cobblestone
  • Reasonable cutoff value of fluid accumulation along deep fascial plane for diagnosing NF according to receiving operating characteristic (ROC) curve
  • Prognostic markers: length of stay (LOS) in hospital, mortality, amputations, number of operations

Results

Ultrasound finding of fluid accumulation and irregular or thickened fascial layer were significantly different between NF and non-NF groups. All patients who had subcutaneous emphysema were in the NF group.

The best cutoff point of fluid accumulation to diagnose NF was 2mm, which had the best accuracy (72.7%), with sensitivity of 75%, a specificity of 70.2%, a positive predictive value of 71.7% and a negative predictive value of 72.7%.

NF patients with fluid accumulation had longer length of stay than NF patients without fluid accumulation (average: 39 days vs. 23 days). Number of operations were not significantly different between NF patients with and without fluid accumulation. All NF patients who had an amputation or died had fluid accumulation.

 

Overall mortality between NF and non-NF groups showed no significant difference.

Strength & Limitations

Strengths

  • Sample size was larger than other studies investigating ultrasonographic findings for NF diagnosis.
  • Study had a comparator groups with clear definitions (NF vs. non-NF).
  • Ultrasound training was standardized and assessed with inter-rater reliability between three emergency physicians as 100%.

Limitations

  • Small, imbalanced sample of NF patients for sensitivity and specificity analysis of fluid accumulation for amputation and mortality. 
  • Study excluded patients with truncal soft tissue infections.
  • Study excluded patients with prior antibiotics or debridement, which may have been NF patients with higher severity and worse prognosis.
  • Patient population were from south Taiwan exclusively.
  • NF patients had higher prevalence of specific co-morbidities (diabetes mellitus, liver cirrhosis, and alcohol use disorder), which could be confounding. 

Authors Conclusion

“The ultrasonographic finding of fluid accumulation along the deep fascia with a cutoff point of more than 2 mm of depth may aid in diagnosing NF. For the prognosis of NF, when fluid accumulation was present along deep fascia on ultrasound, patients with NF had longer lengths of hospital stays and were at risk of amputation or mortality. Ultrasonography is a point-of-care imaging tool that facilitates the diagnosis and prognosis of NF.” (14)

Our Conclusion

Consistent with prior studies and case reports (2-13), this study supports the role of ultrasound in the diagnosis of NF. Trained emergency physicians were able to successfully use ultrasound to detect significant imaging differences in NF patients, including fascial irregularity and deep fascial fluid accumulation. In comparison to Yen et al., this study suggests an even lower cutoff point of fluid accumulation along the deep fascia (2mm vs 4mm) for the highest diagnostic accuracy. We would caution that the finding of "fluid accumulation" was somewhat difficult to interpret in their study.

Further studies with larger sample sizes need to be completed. However, with the diagnostic and prognostic trends seen in this study, ultrasound should be considered as a timely, efficient imaging modality that can help identify patients with clinical suspicion of NF and accelerate OR intervention.

The Bottom Line 

Ultrasound is a viable imaging modality for patients with clinical suspicion of NF that could potentially expedite surgical intervention, though imaging findings may not be as easy to interpret as the authors lay out.

Authors

This post was written by Caresse Vuong, Charles Murchison MD and Amir Aminlari MD.

References

  1. Khamnuan P, Chongruksut W, Jearwattanakanok K, Patumanond J, Yodluangfun S, Tantraworasin A. Necrotizing fasciitis: Risk factors of mortality. Risk Manag Healthc Policy 2015;8:1–7.
  2. Castleberg E, Jenson N, Am Dinh V. Diagnosis of necrotizing fasciitis with bedside ultrasound: The STAFF exam. West J Emerg Med 2014;15:111–113.
  3. Tsai CC, Lai CS, Yu ML, Chou CK, Lin SD. Early diagnosis of necrotizing fasciitis by utilization of ultrasonography. Kaohsiung J Med Sci 1996;12:235–240.
  4. Wronski M, Slodkowski M, Cebulski W, Karkocha D, Krasnodebski IW. Necrotizing fasciitis: Early sonographic diagnosis. J Clin Ultrasound 2011;39:236–239.
  5. Yen ZS, Wang HP, Ma HM, Chen SC, Chen WJ. Ultrasonographic screening of clinically-suspected necrotizing fasciitis. Acad Emerg Med 2002;9:1448–1451.
  6. Bernardi, Emanuele, Antonello Iacobucci, Letizia Barutta, Elisa Pizzolato, Virna Olocco, and Bruno Tartaglino. “A-Lines in Necrotizing Fasciitis of the Lower Limb.” Journal of Ultrasound in Medicine 33, no. 11 (2014): 2044–46. 
  7. Chao, H. C., M. S. Kong, and T. Y. Lin. “Diagnosis of Necrotizing Fasciitis in Children.” Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine 18, no. 4 (April 1999): 277–81. 
  8. Hosek, William T., and Timothy C. Laeger. “Early Diagnosis of Necrotizing Fasciitis with Soft Tissue Ultrasound.” Academic Emergency Medicine 16, no. 10 (2009): 1033–1033. 
  9. Oelze, Lindsay, Stanley Wu, and Jennifer Carnell. “Emergency Ultrasonography for the Early Diagnosis of Necrotizing Fasciitis: A Case Series from the ED.” The American Journal of Emergency Medicine 31, no. 3 (March 1, 2013): 632.e5-632.e7. 
  10. Kehrl, Thompson. “Point-of-Care Ultrasound Diagnosis of Necrotizing Fasciitis Missed by Computed Tomography and Magnetic Resonance Imaging.” The Journal of Emergency Medicine 47, no. 2 (August 2014): 172–75. 
  11. Shyy, William, Roneesha S. Knight, Ruth Goldstein, Eric D. Isaacs, and Nathan A. Teismann. “Sonographic Findings in Necrotizing Fasciitis.” Journal of Ultrasound in Medicine 35, no. 10 (2016): 2273–77. 
  12. Hanif, Muhammad A., and Michael J. Bradley. “Sonographic Findings of Necrotizing Fasciitis in the Breast.” Journal of Clinical Ultrasound: JCU 36, no. 8 (October 2008): 517–19. 
  13. Valle Alonso, Joaquín, Ganapathiram Lakshmanan, and Yasser Saleem. “Use of POCUS Ultrasound in Sepsis, Bedside Diagnosis of Necrotizing Fasciitis.” QJM: An International Journal of Medicine 110, no. 10 (October 1, 2017): 687–88. 
  14. Lin, Chun-Nan, Cheng-Ting Hsiao, Chia-Peng Chang, Tsung-Yu Huang, Kuang-Yu Hsiao, Yi-Chuan Chen, and Wen-Chih Fann. “The Relationship Between Fluid Accumulation in Ultrasonography and the Diagnosis and Prognosis of Patients with Necrotizing Fasciitis.” Ultrasound in Medicine & Biology 45, no. 7 (2019): 1545–50. 

 

Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department

flexor tenosynovitis

Background

Infectious flexor tenosynovitis (FTS) is a surgical emergency. If not treated promptly, infectious FTS carries significant morbidity including loss of function of fingers, necrosis of the tendon, and even digit amputation (1).

Infection can be caused in three ways: direct inoculation, contiguous spread, or hematogenous spread, as seen in cases of disseminated gonococcal infection. Tenosynovitis occurs when fluid collects between the visceral and parietal layer of the tendon, the most common location being in the hand and wrist.

Traditionally, diagnosis of infectious FTS is centered on the tetrad known as Kanavel’s signs (swelling of the finger, finger held in partially flexed position, pain on palpation of the flexor tendon, and pain on passive extension of the finger). While Kanavel’s signs are specific for infectious FTD, in a study of 41 participants with infectious FTS, only 54% of patients taken to the operating room (OR) had all of these signs (2). The gold standard of diagnosis remains surgical exploration and drainage. MRI can aid in the diagnosis of FTS, but this is rarely available in the ED. While radiographs may be obtained to look for trauma, osteomyelitis or a foreign body, they offer minimal to no additional benefit in diagnosing infectious FTS.   

This article presents a case of a 58-year-old man where point of care ultrasound (POCUS) identified tissue necrosis and fluid along the flexor tendon sheath of the hand, aiding in the rapid diagnosis of FTS, adding to the limited body of literature supporting use of POCUS for early diagnosis of infectious FTS.

Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department

Clinical Question

Can point of care ultrasound be used in the emergency department to diagnose infectious FTS?

Methods & Study Design

• Design 

Case report.

• Population 

58 year old male with hypertension, diabetes and end stage renal disease.

• Intervention 

POCUS looking for fluid in flexor tendon sheath. Appropriate technique is shown in the image below, with a linear ultrasound probe placed on the palmar side of the wrist crease. Common findings of FTS are hypoechoic or anechoic fluid surrounding the flexor tendons.

ultrasound flexor tendons
Padrez et al. West J Emerg Med 2015, 16(2)

• Outcomes  

Accurate diagnosis of FTS

 

Results

The physicians found a moderate amount of fluid and echogenic material within the tendon sheath, as noted in the image below. Orthopedics was consulted and patient was started on broad spectrum antibiotics and taken to the operating room. They found extensive pus within the flexor tendon sheath and cultures grew Staph aureus

 

ultrasound flexor tenosynovitis
Padrez et al. West J Emerg Med 2015, 16(2)

Strength & Limitations

The POCUS exam the authors describe is practical and useful. This could feasibly be performed by clinicians with relatively little ultrasound training. As mentioned, FTS is a surgical emergency and remains largely a clinical diagnosis, so any modality that helps bring more certainty to the diagnosis, and lead to quicker definitive treatment, is welcome.

It is unclear what the level of ultrasound training was for the physicians who performed this exam. Another note, it may be difficult to distinguish rheumatologic from infectious causes of tenosynovitis using ultrasound, so clinical context is always important. They also mentioned this can only aid in increasing your suspicion for FTS, it cannot be used to rule it out. 

Authors Conclusion

POCUS may be an ideal adjunct for the ED physician in the evaluation of a patient with suspected infectious FTS 

Our Conclusion

We agree with the authors conclusions that POCUS can be a useful adjunct to clinical exam in diagnosing FTS, with the understanding that POCUS cannot rule out FTS or distinguish rheumatologic from infectious process.

The Bottom Line 

POCUS can be a useful adjunct to clinical exam in diagnosing FTS. Use the linear probe and place at the palmar side of the wrist crease, look for hypoechoic or anechoic material around the flexor tendons with possible thickening of the tendon itself. 

Authors

This post was written by Betial Asmerom and Amir Aminlari MD. Edited by Charles Murchison MD.

References

  1. Mamane, W. et al. Infectious flexor hand tenosynovitis: State of knowledge. A study of 120 cases. J. Orthop. 15, 701–706 (2018).
  2.  
  3. Hubbard, D., Joing, S. & Smith, S. W. Pyogenic Flexor Tenosynovitis by Point-of-care Ultrasound in the Emergency Department. Clin. Pract. Cases Emerg. Med. 2, 235–240 (2018).
  4.  
  5. Padrez et al. Bedsound Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. West J Emerg 2015. 16 (2). 

 

 

Case # 21: A 28 Year Old With Shortness of Breath

echo d sign

 

A previously healthy 28-year-old male presents to the Emergency Department complaining of one month of fatigue, shortness of breath, and dyspnea on exertion. These symptoms were preceded by symptoms of a viral illness which initially improved; however, he had recurrence of symptoms two weeks ago. He was seen at urgent care five days ago and was given steroids and albuterol without improvement. The patient otherwise denies any infectious symptoms, leg swelling, or risk factors for pulmonary embolus or deep vein thrombosis.  

VS: T: 97.7F    BP: 129/87.    HR: 109     RR: 16.    SP02: 95%

Patient is alert and oriented, non-toxic in no distress, and behaving appropriately. Cardiac exam shows a RRR, no murmurs, rubs, or gallops. Lung exam is consistent with shallow breaths and dyspnea with conversation, otherwise lungs are CTAB with no wheezing, rales, or rhonchi. The patient has no chest wall tenderness, no JVD, and no lower extremity edema.

You perform a bedside ECHO and you see the following. What do you see and what is your most likely diagnosis? What is your next step in management?

apical 4 rv strain
psla rv strain
pssa rv strain

Answer and Learning Points

Answer:

In all three cardiac views, there is dilation of the right side of the heart. In the parasternal short axis you see septal bowing into the left side of the heart, also known as the “D” sign (named after the shape of the left ventricle). These findings are indicative of elevated right sided pressure, or right heart strain, which can be seen in conditions such as acute pulmonary embolism, pulmonary hypertension, COPD, and right ventricular infarction. Given the relatively thin free wall of the right ventricle, the likely cause of right heart strain in the above scenario is an acute process.

The patient had a CT scan that revealed extensive pulmonary emboli in all segmental and subsegmental arterial divisions of the lung with findings consistent with pulmonary artery hypertension and severe right heart strain. The EKG obtained had evidence of right heart strain including right axis deviation and diffuse T-wave inversions. The patient was started on heparin and admitted to the ICU.

Learning Points

  • The reported sensitivity and specificity of echocardiography in demonstrating right heart dysfunction are around 56% and 42% respectively (1)
  • Described features of right heart dysfunction include (2)
    1. Dilation of the right ventricle
      • The RV normally appears triangular-shaped and is two-thirds the size of the LV in apical four view (3)
    1. Interventricular septal flattening
      • AKA the “D sign” on parasternal short view or paradoxical septal motion on apical four view
    1. Right ventricular hypertrophy (right ventricular free wall thickness >5mm in diastole)
      • When present, implies some degree of chronicity to the inciting hemodynamic insult
    1. Right ventricular hypokensia
      • Typically quantified as a tricuspid annular plane systolic excursion, as measured by M-mode from the apical 4 chamber view, <1.6 cm
    1. Plethoric vena cava

References

  1. He, H., et-al. Computed tomography evaluation of right heart dysfunction in patients with acute pulmonary embolism. J Comput Assist Tomogr. 2006;30 (2): 262-6.
  2. Rudski, L.G., et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. (2010) Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 23 (7): 685-713
  3. Mallin, M, Dawson, M. Introduction to Bedside Ultrasound: Volume 2. Emergency Ultrasound Solutions, 2013. Apple Books. https://books.apple.com/us/book/introduction-to-bedside-ultrasound-volume-2/id647356692. Accessed April 17th, 2020.


The following authors contributed to this post:

Danika Brodak, MD; Amir Aminlari, MD; Rachna Subramony, MD; Colleen Campbell, MD

Ultrasound-guided supra-inguinal fascia iliaca block: a cadaveric evaluation of a novel approach

fascia iliaca block

Background

Regional anesthesia of the fascia iliaca is well-documented to be a successful way to control acute pain from hip fractures in the emergency department, particularly in those patients at high risk of complications from repeated doses of IV opioids. However, the majority of existing descriptions on technique for performing fascia iliaca blocks focus on approaching from inferior to the inguinal ligament, relying on supra-inguinal spread to block the lateral femoral cutaneous nerve in the iliac fossa. This study aims to investigate the utility in performing suprainguinal injection of anesthetic agents directly into the iliac fossa to provide regional anesthesia.

Ultrasound-guided supra-inguinal fascia iliaca block: a cadaveric evaluation of a novel approach

Clinical Question

Does injecting dye superior to the inguinal ligament provide significant uptake of dye in the femoral, LCFN, and ilioinguinal nerves in cadaveric models?

Methods & Study Design

• Design 

This is an informational study made to illustrate the utility of an alternative supra-inguinal approach for providing regional anesthesia in those patients presenting with acute hip or knee pain.

• Population 

Bilateral injections of 20 mL of 0.25% aniline blue dye were administered to six unembalmed cadavers, for a total of 12 injections available for analysis.

• Intervention 

Bilateral injections of 20 mL of 0.25% aniline blue dye were administered to six unembalmed cadavers via an ultrasound guided approach, and dye uptake was analyzed in anatomic nerve distributions.

Steps of superior approach to fascia iliaca block:

  • Place sterile probe over the inguinal ligament, close to the anterior superior iliac spine
  • Orient linear probe in parasagittal oblique orientation (superior aspect facing medially)
  • Rock the probe so beam faces laterally to enhance fascia iliaca
  • Move probe infero-medially along the line of inguinal ligament until femoral artery is imaged
  • Moving probe supero-laterally helps identify anterior inferior iliac spine (site of rectus femoris attachment)
  • As you move laterally, you see “rising” of ilium towards transducer
  • Identify deep circumflex artery 1-2cm superficial to fascia iliaca
  • Needle introduced 2-4cm inferior to inguinal ligament, and advanced through the fascia iliaca at the level of inguinal ligament.
  • “pop” as needle passes through fascial iliaca and into the iliacus muscle
  • Needle withdrawn to the fascia, and position confirmed by 1cc of local anesthetic.
  • Injection of fluid produces a“lens”that appears. The fluid should then hydro-dissect as it migrates into the iliac fossa
  • End point is when local anesthetic passes freely superiorly over the iliacus muscle and into the iliac fossa.

• Outcomes  

Dye uptake in the femoral, lateral femoral cutaneous nerve, and ilioninguinal nerves after supra-inguinal injection.

Results

    • There was extensive spread of dye identified in the iliac fossa. (50 to 144mm of spread)
    • 10 out of 12 injections also resulted in spread into the thigh along the femoral nerve
    • The femoral nerve was surrounded by dye in all cases
    • The LFCN was identified bilaterally in 5 cadavers, but one cadaver lacked both LFCN. LCFN was surrounded by dye in all cases in which it was present.
    • It is important to realize that the ilioinguinal nerve has significant anatomic variation. The ilioinguinal nerve passed over iliac crest onto iliacus muscle and re-emerged into the abdominal wall anteriorly in 8 cases. In the other four cases it remained in the abdominal wall. It was stained blue 7 out of 8 times in this procedure as it passed over iliac crest.

Strength & Limitations

    • There was no comparison group in this study (supra-inguinal approach was used in all cases).
    • There were significant anatomic variations between cadavers. One cadaver was found to have no lateral femoral cutaneous nerve. There were also significant anatomic variations in positioning of the ilioinguinal nerve.
    • Throughout the article, there were multiple references that the authors institution has performed over 150 supra-inguinal fascia iliata blocks without any short term complications, however no retrospective data was available in the article to confirm this.
    • Low sample population (6 cadavers, 12 nerve blocks)

Authors Conclusion

“Our cadaveric dye-injection study confirms that the ultrasound-guided supra-inguinal approach result in significant spread of injectate with simultaneous involvement of both the femoral nerve and LFCN, in the iliac fossa, in the all the cadavers in which we identified theses nerves by dissection.”

Our Conclusion

This article outlines an interesting alternative approach to providing regional anesthesia for acute pain control of the hip or knee. The majority of existing descriptions on technique for performing fascia iliaca blocks focus on approaching from inferior to the inguinal ligament, relying on supra-inguinal spread to block the lateral femoral cutaneous nerve in the iliac fossa. This study demonstrates consistent bathing of the LFCN and femoral nerve with dye in cadaveric subjects with a supra-inguinal approach. However, this study does not directly demonstrate superior efficacy of the suprainguinal approach when compared to infrainguinal fascia iliaca block. Further patient-oriented studies would be needed to make such a suggestion.

The Bottom Line 

Ultrasound guided suprainguinal fascia iliaca injection of dye in cadaveric subjects shows consistent and significant uptake of injectate of the femoral nerve and LFCN in the iliac fossa. Further studies are needed to show if this provides improved analgesia as compared to the conventional infrainguinal approach. 

Authors

This post was written by Casey Smith, MD. Review and further commentary was provided by Danika Brodak, MD, Emergency Ultrasound Fellow at UCSD and Amir Aminlari, MD, Ultrasound Faculty at UCSD.

References

  1. Hebbard P, Ivanusic J, Sha S. Ultrasound-guided supra-inguinal fascia iliaca block: a cadaveric evaluation of a novel approach. Anaesthesia. 2011;66(4):300‐305. doi:10.1111/j.1365-2044.2011.06628.x

 

Case # 20: Right Lower Quadrant Pain

A 40 year old male presented with a 4 day history of right lower quadrant pain. He reported that the pain was at its worse when it started but gradually improved. When in the ED he noted only minimal discomfort without the help of analgesics.  He denied ever having anorexia, fever, chills, nausea, vomiting, GU complaints. During examination, he had moderate tenderness to palpation in the right lower quadrant without rebound or guarding. 

Vitals:  T 97.7F    BP 130/77    HR 66    RR 16   SP02 100%

An abdominal ultrasound of the RLQ was performed and the following images were seen. What do you see and what is your most likely diagnosis? 

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ezgif.com-crop (2)

Answer and Learning Points

Answer

In both the longitudinal and transverse views, you see a tubular structure in the right lower quadrant that is non- compressible, greater than 6mm (measures 15.6 mm), and lacks peristalsis. You can also appreciate some dependent free fluid around the appendix. These findings are consistent with the diagnosis of acute appendicitis.

CT abdomen/pelvis showed a retrocecal appendix with finding of acute uncomplicated appendicitis. No bowel obstruction or intra-abdominal/pelvic abscesses. Labs showed a slight leukocytosis to 14, otherwise were reassuring. Patient was given a dose of Zosyn in the emergency department and take to the OR for appendectomy by general surgery.

Learning Points

    • Appendicitis is the most common abdominal surgical emergency that presents to the ED in western countries [1]. 
    • The sensitivity and specificity of ultrasound for the diagnosis of appendicitis appears to be around 86% and 81%, respectively, based on results from older studies [2]. 
    • Ultrasound can be used to diagnosis acute appendicitis and may be the imaging modality of choice in certain patient populations such as pregnant women and children [3]. 
    • To obtain images you can use either the linear or curvilinear probe. Ask the patient to point where exactly they hurt and place the probe there. If you don’t see it you can use the landmark of the iliac crest (most lateral), psoas muscle (posterior), and iliac artery (most medial). Move superior and inferior along the iliac artery and the appendix should be just anterior to iliac artery. If you still haven’t found it, “lawnmower” along the right lower quadrant. Look for a tubular, blind ended pouch that has no peristalsis. It should be compressible and measure <6mm in AP diameter [4]. 

References

    1. Caterino, S., et al. Acute abdominal pain in emergency surgery. Clinical epidemiologic study study of 450 patients. Ann Ital Chir. 1997; 68: 807-817.
    2. Lim H, Bae S, Seo G: Diagnosis of acute appendicitis in pregnant women: value of sonography. AJR Am J Roentgenol 1992;159(3): 539–542.
    3. Excerpt From: Mike Mallin & Matthew Dawson. “Introduction to Bedside Ultrasound: Volume 2.” Emergency Ultrasound Solutions, 2013. Apple Books. https://books.apple.com/us/book/introduction-to-bedside-ultrasound-volume-2/id647356692Mallin, M, Dawson, M. Introduction to Bedside Ultrasound: Volume 2. Emergency Ultrasound Solutions, 2013. Apple Books. https://books.apple.com/us/book/introduction-to-bedside-ultrasound-volume-2/id647356692. Accessed April 18th, 2020.
    4. www.5minsono.com

 

The following authors contributed to this post:

Amir Aminlari, MD; Danika Brodak, MD; Michael Macias, MD

Case # 19: Under Pressure

A 27 year-old female presented to the emergency department with a two week history of headache, posterior eye pain, visual changes. She denied trauma, fever, focal neurological changes, or visual field deficits. She was seen by the optometrist earlier in the day and was sent to the ED for further evaluation.  Her neurological examination was normal. 

Eye exam: PERRL, EOMI, no injection/discharge, visual acuity 20/15 OS, 20/20 OD, IOP L19, R19

An ocular ultrasound is performed and the images below are seen. What do you see and what is your most likely diagnosis? What is your management?

ezgif.com-optimize (59)

Left eye

ezgif.com-optimize (58)

 Right eye

Answer and Learning Points

Answer

On both images of the right and left eye you see papilledema which is demonstrated as a bulging optic disc protruding into the posterior chamber.

CT Head non-contrast was obtained which showed " a partially empty pituitary sella which can be seen with intracranial hypertension, otherwise no acute findings." Ophthalmology was consulted. Their exam was unremarkable except for bilateral papilledema. An LP was performed which showed an elevated OP at 36. After large volume CSF removal the patient reported improvement in symptoms. Closing pressure was 22. The CSF studies were unremarkable. Patient was discharged with an MRI/MRV performed as outpatient and neuro-ophthalmology follow up. MRI brain showed mild flattening of the optic nerve heads which is nonspecific but could correlate with intracranial hypertension in the right clinical setting. 

Learning Points

    • Papilledema may be directly visualized with ultrasound as a bulging optic disc elevated more than 0.6mm from the retina. There are also studies that show a correlation between increased intracranial pressure and optic sheath nerve diameter greater than 5mm when measured 3mm posterior to the retina. (1-4)
    • A width of > 5mm has a pooled sensitivity of 90% and specificity of 85% for detecting an ICP > 20mmHg in trauma patients with head injuries (5-6)
    • It is important to note that the optic nerve sheath diameter should be measured when the sides are parallel, as it can be artificially increased otherwise.  (7)
    • When obtaining an ocular ultrasound use the high frequency linear probe on the ocular setting. If there is not an ocular setting, it is best to err on the high side with regard to gain.
    • Although controversial, some sources advise to avoid ocular ultrasound when concerned about globe rupture as any pressure on the eye could worsening the rupture.

References

    1. Marchese, R.F., et al. Identification of optic nerve swelling using point-of-care ocular ultrasound in children. Pediatric Emergency Care. 2018; 34(8):531-536. 
    2. Kimberly, H.H., Shah, S., Marill, K., & Noble, V. Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure. Academic Emergency Medicine. 2008; 15(2):201-4. 
    3. Amini, A., et al. Use of the sonographic diameter of optic nerve sheath to estimate intracranial pressure. The American Journal of Emergency Medicine. 2013; 31(1):236-9.
    4. Xu, W., Gerety, P., Aleman, T., Swanson, J., & Taylor, J. Noninvasive methods of detecting increased intracranial pressure. Child’s Nervous System. 2016; 32(8):1371-86. 
    5. Dubourg, J., et al. Ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure: a systematic review and meta-analysis. Intensive Care Medicine. 2011;37(7):1059–1068.
    6. Rajajee, V., Vanaman, M., Fletcher, J.J., & Jacobs, T.L. Optic nerve ultrasound for the detection of raised intracranial pressure. Neurocritical Care. 2011;15(3):506–515.
    7. Mallin, M, Dawson, M. Introduction to Bedside Ultrasound: Volume 2. Emergency Ultrasound Solutions, 2013. Apple Books. https://books.apple.com/us/book/introduction-to-bedside-ultrasound-volume-2/id647356692. Accessed April 17th, 2020.

The following authors contributed to this post:

Amir Aminlari, MD; Danika Brodak, MD; Michael Macias, MD; Rachna Subramony, MD

Case # 18: Respiratory Distress: It’s not all COVID.

During the COVID-19 pandemic, a 67 year old woman is brought to the ER by family for respiratory distress and altered mental status. She was alert but not oriented and unable to answer questions on arrival with moderate respiratory distress. Family stated that she had a history of asthma and takes "other" medications, but where otherwise unaware of her past medical history. She had been using her inhaler without relief and has not had any sick contacts, cough or fever. 

Vitals: T: 98.7, HR: 112, BP: 190/110, RR: 40, SpO2 80 on RA

She was in moderate respiratory distress, crackles on exam, no pitting edema. She was placed on a non-breather (avoiding NIPPV) and a thoracic plus cardiac ECHO was preformed. 

After reviewing the images, what would you do next?

 

 

CHF vs COVID 1.1
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CHF vs COVID 3
IVC gif

Answer and Learning Points

Answer

The images would suggest that this patient is most likely suffering from heart failure with an acute exacerbation. There are diffuse B-lines, obvious decrease contractility and a dilated IVC. These images are not typical of COVID-19 infections, which have pleural thickening and scattered b-lines (see COVID section).  This patient was put on a nitro drip and given diuretics, with a significant improvement in her respiratory status in the ER. She ultimately tested COVID negative and was discharged from the hospital after aggressive diuresis. 

During the same shift, numerous COVID-19 positive patients were seen. Below are images of COVID-19 cases for comparison and more can be found at The POCUS Atlas. 

While the sensitivity and specificity of ultrasound to diagnosis COVID-19 has yet to be determined, this case illustrates how alternative findings can still impact clinical care and potentially avoid intubation. 

 

COVID +

On the same shift, numerous COVID-19 patients were also seen, with variable pre-test probability. ECHO for these patients would not reveal an alternative diagnosis (such as our CHF case). There were however some classic findings on ultrasound. Note below two patients with thoracic scans. There are scattered B-lines (unlike our CHF patient, who had diffuse B-lines). There is also pleural thickening and at times an irregular pleural border. 

COVID patient 1
thicker pleural lining

Author

Sukhdeep Singh, MD. Clinical Faculty, UCSD Department of Emergency Medicine. Director of POCUS, El Centro Regional Medical Center.

References

  1. DeRose et al, How to Perform Pediatric Lung Ultrasound Examinations in the Time of COVID‐19. Journal of Ultrasound in Medicine. 22 April 2020.
  2. The POCUS Atlas. http://www.thepocusatlas.com/covid19

Case # 17: Par for the Course

An 80 year old man presents to a rural emergency room at 3am with abdominal pain. His past medical history is significant for mild hemophilia A. Six hours prior to arrival, he was driving a golf cart when he struck a pole and the steering wheel hit his stomach.

He initially had no symptoms but began to have abdominal pain while trying to sleep. He also became nauseated and vomited once. He eventually called EMS and was brought to the ER. On arrival, his vitals are as follows. 

Vitals: T: 90.7, HR: 108, BP: 74/48, RR: 28, SpO2 98 on 4L

He is alert, oriented and his only complaint is abdominal pain. A FAST exam was done. What do you see? What are your next steps?

 

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pick me 1
pick me 2

Answer and Learning Points

Answer

Although the quality of images is lacking due to the urgency of the situation and the patient's body habitus, the first image (RUQ) does not show obvious free fluid. The following images (suprapubic and LUQ) clearly show free fluid in the abdomen. 

An emergent evacuation of the patient to a level 1 Trauma service was requested. Patient was transfused with two units of O blood. Due to his history of hemophilia A, the patient was also given factor VIII to 100% repletion. The patient was taken to the OR at the level 1 trauma center where he was found to have a greater omental bleed and was successfully treated with clot evacuation and laceration repair. He was placed on a factor VIII drip postop. 

Learning Points

    • Per ATLS guidelines, a hypotensive patient with a + FAST and no other signs of bleeding warrants immediate surgical exploration. 
    • In a 2018 meta-analysis, a positive FAST has a sensitivity of 68% and a specificity of 95%. Therefore a negative FAST does not rule out the disease, but a positive fast in the correct clinical sitting (such as this) does rule in hemoperitoneum(1). 
    • Hemophiliac patients require factor VIII replacement to 100% in the setting of major trauma, which is typically 50 IU/kg(2). 
 

Author

Feigenbaum, Adam, PA-C. Emergency Medicine Fellow, Naval Medical Center San Diego.

Sukhdeep Singh, MD. Clinical Faculty, UCSD Department of Emergency Medicine. Director of POCUS, El Centro Regional Medical Center.

References

  1. Stengel D et al. Point-of-care ultrasonography for diagnosing thoracoabdominal injuries in patients with blunt trauma. Cochrane Database Syst Rev. 2018. Dec 12;12
  2. Guidelines for Emergency Department Management of Individuals with Hemophilia and Other Bleeding Disorders. https://www.hemophilia.org/Researchers-Healthcare-Providers/Medical-and-Scientific-Advisory-Council-MASAC/MASAC-Recommendations/Guidelines-for-Emergency-Department-Management-of-Individuals-with-Hemophilia-and-Other-Bleeding-Disorders. December 5, 2019

 

Case # 16: The Smoking Gun

A 32 year-old woman with history of pleurisy and systemic lupus erythematosus presented to the emergency department with three weeks of shortness of breath and pleuritic chest pain, acutely worse one day prior to arrival.

She flew into San Diego three days prior to her hospital presentation. She became dyspneic when walking from her hotel bed to the bathroom. On review of systems, she did endorse 3 weeks of right lower leg cramping. She denied fever/chills, cough, back pain, or history of blood clots. She was tachypneic and speaking in short phrases upon arrival.

Vitals: T: 98.3, HR: 130, BP: 142/88, RR: 24, SpO2 97% on RA

A bedside ultrasound ECHO and lower extremity scan was preformed.  What do you see?

 

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RV strain gif
dvt gif 2

Answer and Learning Points

Answer

These ultrasound images show an apical 4 chamber and parasternal short view of the heart, as well as a right lower extremity DVT. The apical 4 chamber demonstrates right ventricular dilation with bowing of the septum into the left ventricle. The parasternal short illustrates “D sign” with right ventricular dilation and bowing/flattening of the interventricular septum leading to decreased left ventricular systolic function. Both views indicate right heart strain in the setting of likely pulmonary embolism. The right lower extremity showed a noncompressible right femoral vein, indicating DVT.

TPA was prepared and ready to give incase patient had worsening hemodynamic instability. She was fortuantley able to tolerate further imaging without HD compromise; CT angio confirmed the diagnosis of pulmonary embolism in bilateral main pulmonary arteries extending into all 5 lobes. Half dose TPA was administered and the patient was admitted to the ICU.

Learning Points

    • Identification of right ventricular dilatation on point-of-care echocardiography for the diagnosis of pulmonary embolism has a sensitivity of 50%, but a specificity of 98%1
    • Patients who present normotensive but have signs of cardiac dysfunction secondary to a PE are classified as submassive, and thrombolytic therapy should be considered2
    • When combining echocardiogram with lower extremity ultrasound, the sensitivity and specificity of cardiac US are 91% and 87%, respectively. Venous US shows a lower sensitivity 56%, but higher specificity 95% than cardiac. When cardiac and venous US are both positive the specificity increases to 100%, whereas when at least one was positive the sensitivity increased to 95.3
    • There is a broad differential of patients presenting to the emergency department with chest pain and shortness of breath. Point-of-care transthoracic cardiac ultrasound in the ED is an effective tool to promptly diagnose acute pulmonary embolism with right heart strain, and rapidly guide management.4,5 This patient with a history of lupus and pericarditis could have presented with cardiac tamponade, and ultrasound did show a small circumferential pericardial effusion, but did not show a collapsing right ventricle that would be expected in tamponade (instead, a dilated RV is seen).6
 

Author

Nicolas Kahl, MD. Emergency Medicine Resident. UCSD Department of Emergency Medicine.

Jessica Oswald, MD. Clinical Faculty, UCSD Department of Emergency Medicine. 

Sukhdeep Singh, MD. Clinical Faculty, UCSD Department of Emergency Medicine. Director of POCUS, El Centro Regional Medical Center.

References

  1. Dresden S, et al. Right Ventricular dilatation on bedside echocardiography performed by emergency physicians aids in diagnosis of pulmonary embolism. Ann Emerg Med; 2014 Jan; 63(1):16-24
  2. Malik Sonika et al. Advanced Management Options for Massive and Submassive Pulmonary Embolism. USC US Cardiology Review. 2016 Feb. 
  3. Nazerian P, et al.Diagnostic accuracy of focused cardiac and venous ultrasound examinations in patients with shock and suspected pulmonary embolism.Intern Emerg Med. 2018 Jun;13(4):567-574
  4. Fields JM, et al. Transthoracic Echocardiography for Diagnosing Pulmonary Embolism: A Systematic Review and Meta-Analysis.J Am Soc Echocardiogr. 2017
  5. Kahl N, et al. Point-of-care Ultrasound Diagnosis of Pulmonary Embolism with Thrombus in Transit.Clin Pract Cases Emerg Med. 2019 Feb; 3(1): 11–12.
  6. Singh, S., et al., Usefulness of right ventricular diastolic collapse in diagnosing cardiac tamponade and comparison to pulsus paradoxus.Am J Cardiol, 1986. 57(8): p. 652-6.