How does bedside ultrasound compare to physical examination in the diagnosis of tendon injuries?

Background

Bedside ultrasound can be used to diagnose full and partial tendon disruptions and can be especially useful in patients who are unable to provide history or otherwise participate in their own care (1). Numerous studies have previously reported the sensitivity and specificity for diagnosing full and partial tendon disruptions to be close to 100% (2-3). However, there is little information in the literature regarding accuracy of bedside musculoskeletal ultrasound in diagnosing these tendon ruptures specifically in the emergency department and whether it expedites patient care. This prospective study describes the sensitivity and specificity of bedside ultrasound in diagnosing tendon injuries and compares it with physical examination. 

How does ultrasound compare to physical examination in diagnosing tendon injuries in the Emergency Department?

Wu TS, Roque PJ, Green J, Drachman D, Khor KN, Rosenberg M, Simpson C. Bedside ultrasound evaluation of tendon injuries. Am J Emerg Med. 2012 Oct;30(8):1617-21.

Clinical Question

What is the sensitivity and specificity of bedside ultrasound in detecting full and partial tendon disruptions, and does use of bedside ultrasound expedite patient care in the emergency department?

Methods & Study Design

Design:
Prospective

Population:
This was a prospective study at 2 different level 1 trauma centers over three years. Inclusion criteria were age at least 16 years old, hemodynamically stable, provided consent and had no prior tendon injury at the site. Exclusion criteria were age less than 16 years old, hemodynamically unstable, requirement of emergent medical or surgical intervention, had prior tendon injury at the site or had local tissue injury that would prevent successful ultrasonographic evaluation.

Intervention:
Emergency medicine attendings and residents were instructed on use of bedside ultrasonography with the linear array transducer to diagnose tendon injury. Patients with suspected tendon injury and meeting inclusion criteria were enrolled in the study. Evaluation consisted of a comprehensive physical exam first followed by a bedside ultrasound. After physical exam evaluation, the attending or resident documented whether the patient had a full, partial or no tear. After ultrasonographic evaluation, the attending or resident documented the degree of tendon injury (0% to 25%, 25% to 50%, 50% to 75%, 75% to 99% or 100%). Definitive tendon injury was determined via exploration of the wound in the emergency department or the operating room or MRI. Secondary information regarding time to diagnosis after ultrasound and time to diagnosis after MRI or wound exploration was also collected.

Outcomes:
Sensitivity, specificity, and accuracy of physical exam and ultrasound were compared to definitive diagnosis determined by wound exploration or MRI.

Results

34 patients were enrolled. Of these 34 patients, 4 patients had partial tendon disruptions, 9 patients had complete tendon disruptions and 21 patients had no tendon disruptions. Use of bedside ultrasonography in diagnosing tendon injury was reported to have sensitivity of 100% and specificity of 95%, accuracy of 97%. Use of physical examination was reported to have sensitivity of 100% and specificity of 76%, accuracy of 85%. Time to diagnosis after ultrasound was 46.3 minutes. Time to diagnosis after wound exploration, consultation or MRI was 138.6 minutes.

Strengths and Limitations

This study demonstrated higher specificity and accuracy with use of ultrasonography to diagnose tendon injury, versus physical examination alone. Strengths of this study included standardization of ultrasonography education for participating emergency medicine attendings and residents between the two institutions, which can contribute to decreased interoperator variability. Limitations of this study include small sample size (n=34) as well as low generalizability. Results of this study may not be seen in institutions with residents and attendings with varying levels of experience and familiarity with tendon ultrasonography or institutions with less advanced ultrasonography equipment.

Author's Conclusions

“Bedside ultrasound is more sensitive and specific than physical examination for detecting tendon lacerations, and takes less time to perform than traditional wound exploration techniques or MRI.”

Our Conclusions

This study found bedside ultrasonography to have similar sensitivity and increased specificity compared to physical examination in diagnosing partial or full tendon injuries. Bedside ultrasonography was associated with decreased time to diagnosis when compared to wound exploration, MRI, or surgical consultation. Patients presenting to the emergency department with suspected tendon injury may benefit from bedside ultrasound in addition to physical examination, especially if physical exam is concerning for tendon injury.

The Bottom Line 

 

 

In this study, use of bedside ultrasound in the ED for patients with suspected tendon injury was associated with improved specificity and expedited diagnosis.

Authors

This post was written by Jennifer Tram, MS4 at UCSD School of Medicine, with editing by Ben Liotta, MD and Amir Aminlari, MD. 

References

1. Wu TS, Roque PJ, Green J, Drachman D, Khor KN, Rosenberg M, Simpson C. Bedside ultrasound evaluation of tendon injuries. Am J Emerg Med. 2012 Oct;30(8):1617-21. doi: 10.1016/j.ajem.2011.11.004

2. Daenen B, Houben G, Bauduin E, et al. Sonography in wrist tendon Pathology. J Clin Ultrasound 2004;32(9):462-9.

3. Teefey SA, Middleton WD, Patel V, et al. The accuracy of high resolution ultrasound for evaluating focal lesions of the hand and wrist. J Hand Surg (Am) 2004;29(3):393-9.

4. Wu TS, Rosenberg M, Vandillen C, Flach F, Simpson C. Bedside ultrasound evaluation of tendon injuries. Ann Emerg Med 2009;54(3): S67.

5. Lee DH, Robbin ML, Galliot R, Graveman V. Ultrasound evaluation of flexor tendon lacerations. J Hand Surgery 2000;25A(2):236-41.

Does adding M-mode to B-mode improve accuracy in diagnosing pneumothorax?

Background

Ultrasound has been shown to be superior to supine chest x-ray in the diagnosis of pneumothorax, with one recent systematic review demonstrating 91% sensitivity using ultrasound compared to 50% using chest x-ray.1 CT scan remains the gold standard in diagnosis but is often not feasible in unstable trauma patients. Ultrasound is recommended by ATLS guidelines for use in trauma patients as part of the eFAST protocol. There are three main described ultrasound findings in pneumothorax: lung sliding, B-lines, and the lung point. While B-mode (2D mode) is commonly described, many resources also suggest the use of M-mode (motion mode).

 

This study evaluates whether the addition of M-mode to B-mode impacts the sensitivity, specificity, and accuracy of bedside ultrasound in the diagnosis of lung sliding. Previous studies have evaluated the accuracy of M-mode on cadaveric subjects2, but no previous studies have investigated the accuracy of M-mode + B-mode compared to B-mode alone in live human subjects.

Does adding M-mode to B-mode improve accuracy in diagnosing pneumothorax?

Avila, J et al. Does the Addition of M-Mode to B-Mode Ultrasound Increase the Accuracy of Identification of Lung Sliding in Traumatic Pneumothoraces?. J Ultrasound Med, 37: 2681-2687   

Clinical Question

Does the addition of M-mode to B-mode improve accuracy in identifying lung sliding? Does this vary by ultrasound experience and level of training?

Methods & Study Design

Design:
Survey

Population:
Emergency Physicians including residents, fellows, and attending physicians

Intervention:
Hemithorax anterior lung field ultrasound scans were performed on 15 patients who had a unilateral pneumothorax confirmed by CT scan. B-mode and corresponding M-mode images were obtained for each patient, with one scan on each side, producing scans of 30 lungs. These images were incorporated into a 30-question quiz in which respondents were asked to identify the presence or absence of lung sliding. One version of the quiz contained B-mode clips alone and one version contained B-mode and M-mode clips for each lung. Respondents were randomized to one of the two quizzes. The quiz was sent to EM residency directors for distribution. One hundred forty physicians responded and were randomized.

Outcomes:
Sensitivity, specificity, and accuracy of the diagnosis of lung sliding, and association with respondent ultrasound experience and level of training.

Results

Overall, the addition of M-Mode to B-Mode resulted in unchanged sensitivity, 93.1% vs 93.2%, improved specificity from 89.8% to 96% (P < 0.0001), and improved accuracy from 91.5% to 94.5% (p=0.0091).

In subgroup analysis, there was no significant difference in accuracy, sensitivity, or specificity when adding M-mode for physicians with more than 250 ultrasound scans previously performed. For physicians with less than 250 total scans previously performed, use of B-mode + M-mode increased accuracy from 88.2% to 94.4% (P = 0.001) and increased specificity from 87.0% to 97.2% (P < 0.0001) compared with B-mode alone. For resident physicians, the addition of M-mode to B-mode significantly improved accuracy from 89.6% to 94.6% (P = 0.0016) and specificity from 87.9% to 95.9% (P < 0.001) for resident physicians. There was no significant improvement for fellows and attending physicians.

Strengths and Limitations

Strengths:

The authors describe methods in detail, including how the ultrasound scans were performed, number of sites scaned, and the type of machine, probe, and settings used. They also collected detailed information on level of ultrasound experience which helps generalize results among emergency physicians with varying levels of ultrasound experience. Ultrasound results were compared to the gold standard of CT scan.

Limitations:

The survey was sent out to residency program directors to distribute to residents, fellows, and attendings, which excludes the large number of practicing emergency physicians in the community. Community physicians may have different levels of experience and formal training with ultrasound and would be an important group to include in terms of study generalizability. Additionally, the sample size was relatively small (140 total participants) and included many more residents (92) than fellows/attendings (48). The images used also did not capture the absence or presence of B-lines, which could also impact interpretation and management. This study evaluated interpretation only and did not evaluate image acquisition, which could impact the outcomes measured and would be more helpful for practical application. Finally, there may be a difference in clinical significance between pneumothorax diagnosed with x-ray or bedside ultrasound versus CT scan– CT may identify more smaller and less clinically relevant pneumothoraces which may be missed on ultrasound.

Author's Conclusions

“The addition of M-mode images to B-mode clips aids in the accurate diagnosis of lung sliding by emergency physicians. The subgroup analysis showed that the benefit of M-mode US disappears after emergency physicians have performed more than 250 US examinations.”

Our Conclusions

The addition of M-mode to B-mode can improve accuracy in identifying lung sliding when evaluating for pneumothorax when performed by emergency physicians with less training or ultrasound experience. Given this benefit, more junior physicians could be encouraged to add M-mode to their evaluation for pneumothorax, especially as the additional image acquisition required is relatively quick.

The Bottom Line 

Adding M-mode to B-mode when using ultrasound to evaluate for pneumothorax improved accuracy amongst emergency physicians with less US experience.

Authors

This post was written by Julie Westover, MS4 at UCSD School of Medicine, with editing by Ben Liotta, MD and Amir Aminlari, MD. 

References

Avila, J., Smith, B., Mead, T., Jurma, D., Dawson, M., Mallin, M. and Dugan, A. (2018), Does the Addition of M-Mode to B-Mode Ultrasound Increase the Accuracy of Identification of Lung Sliding in Traumatic Pneumothoraces?. J Ultrasound Med, 37: 2681-2687. https://doi.org/10.1002/jum.14629

1. Alrajhi K, Woo MY, Vaillancourt C. Test characteristics of ultrasonography for the detection of pneumothorax: a systematic review and analysis. Chest 2012; 141:703–708.
2. Adhikari S, Zeger W, Wadman M, Walker R, Lomneth C. Assessment of a human cadaver model for training emergency medicine res- idents in the ultrasound diagnosis of pneumothorax. Biomed Res Int 2014; 2014:724050

Can Junior EPs Use E-Point Septal Separation to Accurately Estimate Left Ventricular Function?

Background

Point-of-care echocardiography can provide a rapid and accurate assessment of left ventricular function, which is valuable in differentiating causes of hypotension and dyspnea at bedside. Visual estimation of LV function by experienced practitioners has been shown to correlate well with quantitative estimates. However, the number of examinations required before a practitioner is qualified to visually estimate LV function accurately is unknown. Although there are various comparable parameters for assessing LV function, mitral valve E-point septal separation (EPSS) is an easy-to-obtain measurement inversely correlated with LV function. EPSS is an M-mode measurement of the minimum distance between the anterior mitral valve leaflet and the interventricular septum during diastole. Despite its applicability, the reproducibility and accuracy of EPSS as a bedside tool for evaluating LV function in less experienced emergency physicians has yet to be established.

Can Junior Emergency Physicians Use E-Point Septal Separation to Accurately Estimate Left Ventricular Function in Acutely Dyspneic Patients? 

Clinical Question

This study aims to determine if novice emergency physicians (PGY 3 and PGY 4) are able to obtain EPSS measurements and determine if these measurements correlate to echocardiographic visual estimations of LV function by experienced emergency physicians.

Methods & Study Design

Design:
Prospective observational study of correlation between EPSS to visual estimation and LV function in patients who present to ED with chief complaint of acute dyspnea.

Population:
Convenience sampling of 70 subjects enrolled in the ED from July 2008 and July 2009. Criteria for enrollment included age > 18 years, chief complaint of dyspnea, ED length > 2 hours, no history of trauma, and normal mental status. Patients with known history of mitral valve repair or replacement, aortic insufficiency, or mitral stenosis were excluded.

Intervention:
12 senior residents (PGY 3 and PGY 4) in EM residency program with variable levels of ultrasound experiences (70 to 150 total ED ultrasound examinations; average of fewer than 25 cardiac examinations) performed transthoracic echocardiogram of patients with chief complaint of acute dyspnea. Ultrasound examination included subcostal, parasternal long axis (PLAX), parasternal short axis, and apical four chamber views. Six-second video clips in parasternal short and long axes were obtained. M-mode measurements of EPSS were recorded in PLAX orientation after all video clips were obtained and calculated during diastole. All examinations were performed without the presence of experienced emergency physicians (EPs).

Outcomes:
One of two experienced EPs reviewed stored video and visually estimated LVEF. Two board-certified cardiologists subsequently reviewed one-half of the video clips and estimated LVEF, blinded to both junior EPs’ EPSS measurements and visual estimations by experienced EPs.

Results

58 out of 70 enrolled subjects had complete echocardiographic studies recorded.

Concordance rates between EPSS measurements by EPs and cardiologist for LVEF were acceptable with kappa for visual LVEF estimation of 0.75 (95% CI = 0.48 to 1.00).

Spearman correlation analysis revealed significant correlation (p = -0.844, p< 0.001) between novice physicians’ measurements of EPSS and visual estimation of LVEF by experienced EPs.

Strengths and Limitations

This study compared EPSS measurement by junior EPs with visual assessment by experienced EPs showing a strong correlation. Experienced EPs were not blinded to results, which may have induced bias, but the authors find this less likely given what they interpret as good agreement on visual estimations between experienced EPs and blinded cardiologists. It is debatable whether the agreement between EPs and cardiologists with kappa of 0.75 represents good agreement. This study utilized a convenience sampling design due to logistical constraints, which may impact the generalizability of its results. Many subjects were excluded for incomplete ultrasound views, but authors note that junior EPs were actually able to assess EPSS for all subjects, further supporting the use of this measurement even when other views are difficult to obtain.

Authors Conclusions

PGY 3 and PGY 4 EM residents were able to obtain measurements of EPSS that correlated closely with visual assessments of LVEF by experienced emergency physicians with extensive point-of-care ultrasound and echocardiography experience. EPSS can serve as a quantitative alternative to visual estimation of LVEF in dyspneic ED patients.

Our Conclusions

Rapid assessment of LVEF with bedside echocardiography can provide useful clinical information in the acutely dyspneic patient. The level of expertise required to accurately visually assess a LVEF is unknown. This study supports EPSS as a useful quantitative addition to visual estimation of LVEF in patients with acute dyspnea for novice emergency physicians with less echocardiography experience. The level of correlation between EPSS and visual estimation was not perfect, suggesting use of EPSS as an addition to rather than replacement for standard visual estimation.

The Bottom Line 

EPSS can serve as a quantitative addition to qualitative visual estimation of LVEF with bedside echocardiography, especially for less experienced EM practitioners.

Authors

This post was written by Eugene Han, MS4 at UCSD School of Medicine, with editing by Ben Liotta, MD and Amir Aminlari, MD. 

References

1. Secko MA, Lazar JM, Salciccioli LA, Stone MB. Can junior emergency physicians use E-point septal separation to accurately estimate left ventricular function in acutely dyspneic patients? Acad Emerg Med. 2011 Nov;18(11):1223-6. doi: 10.1111/j.1553-2712.2011.01196.x. Epub 2011 Nov 1. PMID: 22044429.
2. McKaigney CJ, Krantz MJ, La Rocque CL, Hurst ND, Buchanan MS, Kendall JL. E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction. Am J Emerg Med. 2014 Jun;32(6):493-7. doi: 10.1016/j.ajem.2014.01.045. Epub 2014 Feb 3. PMID: 24630604.
3. Shahgaldi K, Gudmundsson P, Manouras A, Brodin LA, Winter R. Visually estimated ejection fraction by two dimensional and triplane echocardiography is closely correlated with quantitative ejection fraction by real-time three dimensional echocardiography. Cardiovasc Ultrasound. 2009 Aug 25;7:41. doi: 10.1186/1476-7120-7-41. PMID: 19706183; PMCID: PMC2747837.
4. McGowan JH, Cleland JG. Reliability of reporting left ventricular systolic function by echocardiography: a systematic review of 3 methods. Am Heart J. 2003 Sep;146(3):388-97. doi: 10.1016/S0002-8703(03)00248-5. PMID: 12947354.
5. Jacob M, Shokoohi H, Moideen F, Pousson A, Boniface K. An Echocardiography Training Program for Improving the Left Ventricular Function Interpretation in Emergency Department; a Brief Report. Emerg (Tehran). 2017;5(1):e70. Epub 2017 Jun 15. PMID: 29201952; PMCID: PMC5703747.

Case 27: Ectopic Pregnancy

A 43 year old female with no past medical history presents to the Emergency Department (ED) with lower abdominal pain for the last three hours. She says she knows she is pregnant from a home pregnancy test, but has not had any appointment with obstetrics and has not had an ultrasound yet. She denies any vaginal bleeding.  

Vitals: BP 120/65 mmHg, HR 85, O2 100% on RA.

She is comfortable appearing, her abdominal exam shows mild tenderness to palpation diffusely in the lower abdomen with no rebound and her pelvic exam shows a closed os with no bleeding.

Her point-of-care urine pregnancy test is positive.

You perform a trans-abdominal bedside ultrasound, what do you see?  What are your next steps?

pelvic free fluid
ectopic
positive fast

Answer and Learning Points

Answer:

The first image is a transverse view of the uterus that shows free fluid in the retcouterine pouch (Pouch of Douglas). The second image is another transverse view of the uterus that also shows free fluid in the rectouterine pouch and then fans through to scan the uterus and adnexa. From what we see there is no gestational sac in the uterus and if you look closely there appears to be a heterogenous structure in the left adnexa. The final view is a FAST view in the right upper quadrant, looking at Morrison's Pouch. We see free fluid here as well. 

These findings - a positive pregnancy test, free fluid in the pelvis and no clear intra-uterine pregnancy indicates an ectopic pregnacny until proven otherwise. The next step should be a tranvaginal ultrasound and consultation with Gynecology. 

Conclusion and Learning Points:

The transvaginal ultrasound revealed a left-sided ectopic pregnancy, as seen in the following picture. They identified a fetal pole and even a fetal heart rate in the ectopic pregnancy. The patient was taken to the operating room with Gynecology and had a salpingectomy without complications. She was discharged home three days later. 

Learning Points:

    • Any female of child-bearing age with abdominal pain should be considered for ectopic pregnancy
    • Ultrasound findings in ectopic pregnancy will not always show the ectopic itself, but rather findings suggestive of ectopic:
      • Intra-abdominal free fluid
      • No clear intra-uterine pregnancy (patients with ectopic will sometimes still have a "pseudo-gestational sac" that appears similar to a gestational sac, but there will be no yolk sac or fetal pole)
      • Heterogenous adnexal structure
    • You should not wait for B-HCG measurements to consider ectopic pregnancy, case reports have shown ectopic pregnancies with minimal HCG levels can still rupture (1)

References

1. Fu, Joyce, et al. Rupture of ectopic pregnancy with minimally detectable beta-human chorionic gonadotropin levels: a report of 2 cases. J Reprod Med. 2007 Jun;52(6):541-2.

This post was written by Charles Murchison MD and Anthony Medak MD, with further editing by Amir Aminlari MD.

Serratus Anterior Plane Block for Thoracic Wall Pain

Background

 

The serratus anterior plane block (SAPB) is a field block that provides analgesia from T2 to T9 dermatomes of the hemithorax by anesthetizing the lateral cutaneous branches of the intercostal nerves in that area. It was first described in a 2013 study demonstrating long-lasting thoracic-wall anesthesia with no significant adverse effects (1). It has since been utilized by anesthesia for prophylactic treatment of post-thoracotomy and post-mastectomy pain (2-4) and has demonstrated utility for treatment of rib fracture pain in the acute setting (5)

This case series describes its use in the Emergency Department (ED) for patients with thoracic wall pain from rib fractures, herpes zoster and chest tube placement. 

Serratus Anterior Plane Block in the Emergency Department: A Case Series.

Clinical Question

Is the SAPB feasible, safe and efficacious when used for a variety of thoracic wall pain syndromes in the ED?

Methods & Study Design

Case series in which six patients (age 60-94) underwent SAPB for treatment of thoracic pain.  Exclusion criteria were not specified; however, patients were included regardless of pre-procedural, multimodal analgesic use.  The authors recorded extent of injury and indication for SAPB. Outcomes of interest included efficacy of the nerve block and adverse events due to SABP during hospital stay.

SAPB was performed as follows: 25-30 mL of anesthetic (0.25% bupivacaine) was injected under ultrasound-guidance into the serratus anterior plane, either superficial (n=4) or deep (n=2) to the serratus anterior muscle. Sonographic landmarks for identification of the injection site included the lateral borders of the latissimus dorsi muscle and pectoralis muscle.

Image 1: Serratus anterior plane block sono-anatomy. Yellow line, target plane; purple-dotted line, needle; blue line, pleura. SCT, subcutaneous tissue; SAM, serratus anterior muscle; LDM, latissimus dorsi muscle; ICM, intercostal muscle (Lin et al 2020).

Results

SAPB was most commonly performed for pain related to anterior or posterior rib fractures (n=4), that was inadequately controlled with parenteral opioids.  SAPB provided complete or near-complete pain relief in these patients.  Additionally, SAPB resulted in significant pain relief for acute herpes zoster pain (n=1) and pre-procedural analgesia prior to tube thoracostomy (n=1).  Both superficial and deep injection locations resulted in effective analgesia.  No adverse events were noted.

Strength & Limitations

This is the first study to demonstrate efficacy of the SAPB for acute herpes zoster pain and procedural pain, and it adds to the growing body of literature supporting the use of SAPB for rib fracture pain. 

Limitations of this study include small sample size and lack of systematic data collection.  The authors note there is a possibility that physicians may not have documented all side effects.  Additionally, patients received non-standardized dosing of parenteral pain medication prior to SABP, therefore underdosing may have exaggerated the impact of the nerve block on pain relief.  Generalizability is limited as nerve blocks were performed by ultrasound fellowship-trained emergency physicians.

Authors Conclusion

“SAPB can be an effective analgesic modality for thoracic diseases and injuries including rib fractures, herpes zoster, and thoracostomy placement.”

Our Conclusion

SAPB was an effective adjunct to parenteral opioids in this case series.  Though limited, early data suggests that this is a safe and effective procedure.  Additional prospective studies are needed to compare SAPB to traditional techniques for the treatment of pain related to acute herpes zoster, thoracostomy, and rib fracture.

The Bottom Line 

 

Serratus anterior plane block, when performed by appropriately-trained physicians, is an effective and safe alternative to parenteral opioids and can provide significant, long-lasting analgesia for a variety of painful thoracic conditions. 

For more on the serratus anterior plane block see here:

Highland Ultrasound 

 

Authors

This post was written by Greta Davis, MS4 at UCSD School of Medicine, Charles Murchison, MD and Amir Aminlari MD. 

References

Lin J, Hoffman T, Badashova K, Motov S, Haines L. Serratus Anterior Plane Block in the Emergency Department: A Case Series. Clin Prac Cases Emerg Med. 2020 Feb;4(1):21-25.

1. Blanco R, Parras T, McDonnell JG, et al. Serratus plane block: a novel ultrasound-guided thoracic wall nerve block. Anaesthesia. 2013;68:1107-13.

2. Khalil AE, Abdallah NM, Bashandy GM, et al. Ultrasound-guided serratus anterior plane block versus thoracic epidural analgesia for thoracotomy pain. J Cardiothorac Vasc Anesth. 2017;31(1):152-8.

3. Rahimzadeh P, Imani F, Faiz SHR, et al. Impact of the ultrasound-guided serratus anterior plane block on post-mastectomy pain: a randomized clinical study. Turk J Anaesthesiol Reanim. 2018;46(5):388-92.

4. Madabushi R, Tewari S, Gautam SKS, et al. Serratus anterior plane block: a new analgesic technique for post-thoracotomy pain. Pain Physician. 2015;18(3):E421-4.

5. Durant E, Dixon B, Luftig J, et al. Ultrasound-guided serratus plane block for ED rib fracture pain control. Am J Emerg Med. 2017;35(1):197.e3-6.

Case 26: Genicular Nerve Block for Knee Pain – A Novel Technique

A 68 year old female with no significant past medical history presents to the Emergency Department (ED) with one day of right knee pain after falling off her bicycle onto her right side. She was immediately unable to bear weight on her right leg. 

 

Vitals: T 98.3, HR 73, RR 18, BP 114/70, SpO2 99%

 

Right leg exam: mild right knee effusion. No ligamentous laxity. Tenderness to palpation over lateral joint line > medial joint line. Tenderness to palpation over proximal anterior tibia. Knee extension limited due to pain. Neurovascularly intact with soft compartments.

 

Radiographic imaging demonstrated an isolated right tibial plateau fracture depression of the lateral plateau. The patient reports she is in severe pain but dislikes taking both over-the-counter and opioid pain medications. 

What nerves may be targeted to provide pain relief to her knee while maintaining motor function? What anatomic landmarks should be used on ultrasound to identify the branches of this nerve?

Answer and Learning Points

The genicular nerves derive from various major lower extremity nerve branches (femoral, obturator, sciatic, tibial) nerves and provide sensation to the knee capsule and joint. Cadaveric studies suggest that most genicular nerves are easily identifiable landmarks that may be used for therapeutic purposes. 5  Genicular nerve blocks (GNB) are traditionally used in this setting of chronic osteoarthritis knee pain via radiofrequency ablation or perioperative knee pain via ultrasound (1-4, 9).

The use of a GNBs in the ED is a novel technique to provide motor-sparing, pain relief for acute knee pain. This 68 year old patient with an isolated lateral tibial plateau fracture reported 4/10 pain over her proximal tibia at rest and 8/10 over her proximal tibia with movement. Written informed consent was obtained for GNBs of her right knee. Anatomic landmarks for the superior lateral (Image A,B) , superior medial (Image C,D), and inferior medial (Image D,E,F) genicular nerves were identified on ultrasound.

genicular nerve block

genicular nerve block

genicular nerve block

The ultrasound probe was placed in the sagittal orientation for each site. The superior lateral genicular nerve was located on ultrasound at the junction of the lateral femoral epicondyle and the epiphysis of the shaft of the femur, adjacent to the superior lateral genicular artery (Image A,B). The superior medial genicular nerve (SMGN) can be identified on ultrasound at the junction of the medial femoral epicondyle and the epiphysis of the shaft of the femur, adjacent to the superior medial genicular artery (Image C, D). The inferior medial genicular nerve (IMGN) can be identified on ultrasound at the junction of the medial tibial epicondyle and the epiphysis of the shaft of the tibia, adjacent to the inferior medial genicular artery (Image E, F, G) (6-8).

Under ultrasound guidance and using sterile technique, the skin was first anesthetized with 1% lidocaine after each site. A 21-gauge, 2 inch echogenic needle was inserted percutaneously and advanced under ultrasound guidance using an out-of-plate technique to inject 1.5 mL of 0.5% bupivacaine around the right superior lateral, superior medial, and inferior medial genicular nerves. 

Learning points

    • Genicular nerves derive from several lower extremity nerves and supply sensory innervation to the knee. 
    • The superior lateral, superior medial, and inferior medial genicular nerves are commonly targeted for pain relief with chronic knee osteoarthritis and postoperative pain.
    • The SLGN, SMGN, IMGN are easily located on ultrasound using anatomic landmarks (junction between epicondyles and epiphysis of the femur and tibia, adjacent to paired genicular arteries).
    • To obtain the images, you can use the linear probe in the sagittal location over lateral femoral epicondyle, medial femoral epicondyle, and medial tibial epicondyle.

References

1. Ahmed, Arif. “Ultrasound-guided radiofrequency ablation of genicular nerves of knee for relief of intractable pain from knee osteoarthritis: a case series.” British Journal of Pain, vol. 12, no. 3, 2017, pp. 145-154, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6058456/. Accessed 18 November 2020.

2. Caldwell, George L. “Reduced Opioid Use After Surgeon-Administered Genicular Nerve Block for Anterior Cruciate Ligament Reconstruction in Adults and Adolescents.” HSS Journal, vol. 15, no. 1, 2019, pp. 42-50, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6384209/. Accessed 18 November 2020.

3. Cankurtaran, Damla. “Comparing the effectiveness of ultrasound guided versus blind genicular nerve block on pain, muscle strength with isokinetic device, physical function and quality of life in chronic knee osteoarthritis: a prospective randomized controlled study.” Korean J Pain, vol. 33, no. 3, 2020, pp. 258 - 266, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7336352/. Accessed 18 November 2020.

4. Erdem, Yusuf. “The Efficacy of Ultrasound-Guided Pulsed Radiofrequency of Genicular Nerves in the Treatment of Chronic Knee Pain Due to Severe Degenerative Disease or Previous Total Knee Arthroplasty.” Med Sci Monit, vol. 25, 2019, pp. 1857 - 1863, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6423735/. Accessed 18 November 2020.

5. Fonkoué, Loïc. “Distribution of sensory nerves supplying the knee joint capsule and implications for genicular blockade and radiofrequency ablation: an anatomical study.” Surgical and Radiologic Anatomy, vol. 41, 2019, 1461–1471(2019), https://link.springer.com/article/10.1007/s00276-019-02291-y#citeas. Accessed 18 November 2020.

6. Güzelküçük, DemIr. “A different approach to the management of osteoarthritis in the knee: Ultrasound guided genicular nerve block.” Pain Medicine, vol. 18, no. 1, pp. 181 - 183, https://academic.oup.com/painmedicine/article/18/1/181/2924744. Accessed 18 November 2020.

7. Kim, Doo-Hwan. “Ultrasound-Guided Genicular Nerve Block for Knee Osteoarthritis: A Double-Blind, Randomized Controlled Trial of Local Anesthetic Alone or in Combination with Corticosteroid.” Pain Physician, vol. 21, 2018, pp. 41 - 51, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6058456/. Accessed 18 November 2020.

8. Protzman, Nicole. “Examining the feasibility of radiofrequency treatment for chronic knee pain after total knee arthroplasty.” PM&R, vol. 6, no. 4, 2014, pp. 373 - 376, https://pubmed.ncbi.nlm.nih.gov/24373908/. Accessed 18 November 2020.

9. Sahoo, Rajendra K. “Genicular nerve block for postoperative pain relief after total knee replacement.” Saudi J Anaesth, vol. 12, no. 2, 2020, pp. 235 - 237, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164458/. Accessed 18 November 2020.

This post was written by Julia Sobel MD, with editing from Jessica Oswald MD, Charles Murchison MD and Amir Aminlari MD.

Erector Spinae Nerve Block for Abdominal Pain – A Case for Better Analgesia

Background

 

In the age of the opioid epidemic, there is a need for multi-modal pain control techniques, and nerve blocks will likely be an increasingly important piece of the puzzle, particularly in the Emergency Department. Ultrasound-guided nerve blocks for musculoskeletal complaints are now standard practice for many emergency physicians, so it is a reasonable next step to utilize this modality in lieu of opioids for abdominal complaints as well.

The erector spinae plane (ESP) block has been shown to improve pain control for rib fractures in the emergency department, and a more inferior approach has demonstrated success in the perioperative period for abdominal surgeries (1,2). However, this type of block has not been studied for the management of abdominal pain in the emergency department.

This study examined the efficacy of the ESP block on patients with acute appendicitis to see if it could reduce opioid use.

 

A Novel Technique to Reduce Reliance on Opioids for Analgesia from Acute Appendicitis: The Ultrasound-guided Erector Spinae Plane Block

Clinical Question

Can an inferiorly located, ultrasound-guided erector spinae plane block successfully manage the pain of acute appendicitis in the emergency department setting?

Methods & Study Design

Case report in which ultrasound guidance was used to perform an ESP block at the L1 level.

The patient was a 24-year-old male with uncomplicated appendicitis as diagnosed on CT. The location for needle insertion was identified by palpating the L1 spinous process and placing a linear probe 3 cm lateral, at the transverse process. A Touhy needle was advanced under ultrasound guidance to the level of the transverse process, and saline hydrodissection was used to confirm the needle tip in the fascial plane. Then, 20mL of 1% lidocaine was injected.

Results

Initially, the patient was reporting 7/10 pain following analgesia with 0.5 mg IV hydromorphone, 30 mg IV ketorolac, and 1 g IV acetaminophen. Thirty minutes following placement of the erector spinae plane block, the patient reported 0/10 pain without palpation, and 3/10 pain with deep palpation. Testing to cold revealed loss of sensation between the T10-L2 dermatomes. The patient did not require additional analgesia during the rest of his 5.5-hour emergency department stay. 

Strength & Limitations

While this is a case study of only one patient, it provides explicit guidance on performing an erector spinae plane block in the emergency department setting. However, the primary method of assessing pain control is inherently subjective and may be limited by the patient’s perception of the efficacy of the block. Further, the patient had already received analgesia, which may have impacted the efficacy of the block over the course of the ED stay. 

Authors Conclusion

A single injection, ultrasound-guided erector spinae plane block can provide complete analgesia for appendicitis.

Our Conclusion

Performing an erector spinae plane block at the L1 level was an effective adjunct to opioid analgesia in this case. Because of the relative safety of this block and efficacy in this case, it warrants further investigation as to the ideal level for pain control, particularly in a larger sample of patients. 

The Bottom Line 

 

When performed in a more inferior position, an ultrasound-guided erector spinae plane block may be an effective form of analgesia for appendicitis in the emergency department setting. 

For excellent guides on how to perform erector spinae blocks see here:

EMRA

Highland Ultrasound 

Authors

This post was written by Kaley Waring, MS4 at UCSD School of Medicine, Charles Murchison MD and Amir Aminlari MD.

References

Mantuani et al. A Novel Technique to Reduce Reliance on Opioids for Analgesia from Acute Appendicitis: The Ultrasound-guided Erector Spinae Plane Block. Clin Pract Cases Emerg Med. 2019 Aug; 3(3): 248–251.

1. Luftig J, Mantuani D, Herring AA, et al. Successful emergency pain control for posterior rib fractures with ultrasound-guided erector spinae plane block. Am J Emerg Med. 2018;36(8):1391–6

2. Chin KJ, Adhikary S, Sarwani N, et al. The analgesic efficacy of pre-operative bilateral erector spinae plane (ESP) blocks in patients having ventral hernia repair. Anaesthesia. 2017;72(4):452–60

Case 25: Aortic Dissection

A 44 year old male with a history of heroin abuse presents to the emergency department with altered mental status.  Per EMS, the patient was found on the street with decreased level of consciousness and poor respiratory effort.  EMS was concerned about opioid overdose, and he was treated with 4mg Narcan, with improvement in his mental status.  

Upon arrival to the ED, he was noted to be agitated and tachypneic with RR in the 40’s.  

Vitals: BP 90/65 mmHg, HR 110, O2 100% on RA, glucose 158.

He is alert and oriented to person, month, and place, but appears agitated and confused.  He denies any complaints other than shortness of breath, and states he felt fine before using heroin.  He denies any past medical history.

Exam notable for tachycardia, diffuse rhonchi throughout all lung fields, 2+ nonpitting lower extremity edema.  He is neurologically intact with 2+ pulses throughout.

A bedside echocardiogram was performed, what do you see?  What are your next steps?

PS long
dilated aortic root
aortic dissection suprasternal ultrasound
abdominal aortic dissection ultrasound
abdominal aortic dissection ultrasound
dissection to iliacs ultrasound

Answer and Learning Points

Answer:

The first two images show a parasternal long-axis view, with a dilated aortic root measuring approximately 4.2cm.  Also notice the pericardial effusion with a homogenous layer that appears fixed to the pericardium.  At the time it was unclear whether this represented a clot within the pericardial sac, or was superficial to it.

Given the dilated aortic root, a suprasternal short-axis view was obtained to assess the proximal aorta, with the short axis view seen on the third image.  A flap was visualized in the aortic lumen, significant for an ascending aortic dissection.  The dissection was then visualized in the abdominal aorta, extending distal to the common iliac arteries, seen in the last images.

The patient was placed on esmolol drip and later required vasopressor support.  CT angiography was obtained, confirming a Type A aortic dissection.  He was transferred to a nearby hospital for emergent repair of his ascending and descending aortic dissection.  

Per the operative report, the patient had developed a significant pericardial effusion by the time he reached the OR, and the visualized homogenous layer above most likely represented a blood clot within the pericardium.

Learning Points:

    • While CTA remains the gold standard for diagnosis of aortic dissection, POCUS remains a great tool for diagnosing both ascending and descending aortic dissection, particularly in the unstable patient.
    • In addition to directly visualizing the dissection flap, TTE can also be used to identify patients with high risk features, such as those with cardiac tamponade, severe aortic dilatation, severe aortic regurgitation, regional wall motion abnormalities, and decreased ejection fraction (1).
    • TTE has been shown to have a sensitivity of 78-90% and specificity 87-96% for type A dissection in older studies (2,3), and in more recent studies showing improved sensitivity up to 97-99% (1,4,5) and specificity 100% (4) with improved image quality.
    • The suprasternal notch views are particularly useful in evaluating the proximal ascending aorta, and allow the operator to assess for aortic dissection, coarctation, dilatation of the aortic arch, and retrograde flow from the descending aorta.

References

1. Sobczyk D, Nycz K. Feasibility and accuracy of bedside transthoracic echocardiography in diagnosis of acute proximal aortic dissection. Cardiovasc Ultrasound. 2015;13:15.

2. Evangelista A, Flachskamp FA, Erbel R, Antonini-Canterin F, Vlachopoulos C, Rocchi G, et al. Echocardiography in aortic diseases: EAE recommendations for clinical practice. Eur J Echocardiogr. 2010;11:645–58. doi: 10.1093/ejechocard/jeq056.

3. Nienaber CA, von Kodolitsch Y, Nicolas V, Siglow V, Piepho A, Jaup T, et al. The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N Engl J Med. 1993;328:1–9. doi: 10.1056/NEJM199301073280101.

4. Cecconi M, Chirillo F, Constantini C, Iacobone G, Lopez E, Zanoli R, et al. The role of transthoracic echocardiography in the diagnosis and management of acute type A aortic syndrome. Am Heart J. 2012;163(1):112–8. doi: 10.1016/j.ahj.2011.09.022.

5. Nazerian, P., Vanni, S., Castelli, M. et al.Diagnostic performance of emergency transthoracic focus cardiac ultrasound in suspected acute type A aortic dissection. Intern Emerg Med9, 665–670 (2014). https://doi.org/10.1007/s11739-014-1080-9

This post was written by Rachna Subramony MD, Alex Anshus MD, with editing from Sukhdeep Singh MD, Charles Murchison MD and Amir Aminlari MD.

A Practical Guide to Placing Ultrasound-Guided Peripheral IVs

ultrasound iv

Background

 

Peripheral IV placement is one of the most common procedures performed in hospitals, with hundreds of millions performed each year. For the most part, IVs are successfully placed in the traditional way - using landmarks and visualization/palpation of the vessels. But as we all know, there are several patient factors that can make peripheral IV placement more difficult, including obesity, edema, a history of IV drug use, sickle cell disease, lupus, diabetes, etc.

Ultrasound-guided IV placement is increasingly used in the emergency room, medicine floors and ICUs in patients with difficult IV access, but  the research is clear that there is a higher premature failure rate with ultrasound-guided IVs (1). 

This practical guideline details several considerations that may help reduce the premature failure rate of ultrasound-guided IV catheter placement.  

 

Ultrasound-Guided Peripheral Venous Cannulation in Critically Ill Patients: a Practical Guideline

Clinical Question

What are key concepts to help reduce ultrasound guided peripheral IV catheter complications, prolong life of catheters, and increase rate of successful placement?

Methods & Study Design

• Design 

Review paper

Results

There are six key concepts to help minimize complications and increase duration of ultrasound-guided peripheral IV catheter placement.

Strength & Limitations

Potential limits to these guidelines include ultrasound experience level of a person placing IV catheters, whether the necessary equipment is routinely available at lower resource centers, and the setting in which IV cannulation takes place (e.g. trauma or non-trauma). The access and cost of ultra-long peripheral and midline catheters may limit use given potential for high utilization. 

Authors Conclusion

Practitioners should consider several issues when inserting intravenous peripheral catheters under ultrasound guidance, aiming to improve success rate, avoid complications and lengthen the survival of the catheter. Based on available data and everyday practice, all indicate that catheters longer than standard size are needed for US-guided peripheral venous cannulation, with the purpose of minimizing premature catheter failure. This is a call for attention to catheter manufacturers, since a more affordable solution at hand is expected from them shortly.”

Our Conclusion

For placement of ultrasound-guided peripheral IVs consider these rules:

    • Always use a long IV catheter, preferably 6 cm or longer
    • Choose veins that are:
      • At least 4 mm in diameter
      • At most 1.5 cm deep
      • As distal as possible, preferably distal to the antecubital fossa
    • At last 2.75 cm of the catheter should be in the vein
    • Check IV placement by flushing saline and use the ultrasound to watch a proximal vessel for turbulent flow

The Bottom Line 

When identifying an appropriate vein for ultrasound guided IV access, choose a superficial, patent, large, distal vein to minimize distance needed for the catheter to travel. Ensure adequate catheter length and confirm catheter position after placement to decrease failure rate.

Authors

This post was written by Tori Speck, MS4 at UCSD School of Medicine, Charles Murchison, MD and Amir Aminlari, MD. 

References

Blanco, Pablo. “Ultrasound-Guided Peripheral Venous Cannulation in Critically Ill Patients: a Practical Guideline.” The Ultrasound Journal, Springer Milan, 17 Oct. 2019, www.ncbi.nlm.nih.gov/pubmed/31624927. 

1. Bahl, Amit, et al. “Ultralong Versus Standard Long Peripheral Intravenous Catheters: A Randomized Controlled Trial of Ultrasonographically Guided Catheter Survival.” Annals of Emergency Medicine, Mosby, 16 Jan. 2020, www.sciencedirect.com/science/article/pii/S0196064419313836. 

2. Gottlieb, Michael et al. “Comparison of Short- vs Long-axis Technique for Ultrasound-guided Peripheral Line Placement: A Systematic Review and Meta-analysis.” Cureus vol. 10,5 e2718. 31 May. 2018, doi:10.7759/cureus.2718

3. Presley, Brad. “Ultrasound Guided Intravenous Access.” StatPearls [Internet]., U.S. National Library of Medicine, 31 July 2020, www.ncbi.nlm.nih.gov/books/NBK525988/.

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