Diagnostic Emergency Ultrasound: Assessment Techniques In The Pediatric Patient

Table of Contents

 

1. Abstract
2. Case Presentations
3. Introduction
4. Critical Appraisal of the Literature
5. Prehospital Care
6. Emergency Department Evaluation With Ultrasound
   1. Cardiac Ultrasound
      1. Technique
         • Subxiphoid View
         • Apical 4-Chamber View
         • Parasternal Long-Axis View
         • Parasternal Short-Axis View
         • Other Cardiac Views
      2. Indications For Cardiac Ultrasound
         • Pericardial Effusion And Tamponade
         • Assessment Of Left Ventricular Ejection Fraction
         • Cardiac Arrest
      3. Future Applications
   2. Trauma
      1. FAST
      2. E-FAST
         • E-FAST To Detect Pneumothorax
         • E-FAST To Detect Hemothorax
   3. Skull Fracture
      1. Technique
      2. Future Applications
         • Lung Ultrasound
      3. Technique
      4. Pneumonia
      5. Future Applications
   4. Intravascular Volume Assessment
      1. Technique
   5. Abdominal Ultrasound
      1. Indications For Abdominal Ultrasound
      2. Appendicitis
      3. Technique
      4. Intussusception
      5. Technique
      6. Pyloric Stenosis
      7. Cholecystitis
   6. Testicular Torsion
      1. Technique
   7. Pregnancy In The First Trimester
7. Controversies And Cutting Edge
8. Summary
9. Risk Management Pitfalls In The Use Of Diagnostic Ultrasound To Evaluate Pediatric Patients In The Emergency Department
10. Time- And Cost-Effective Strategies
11. Case Conclusions
12. Figures
    1. Figure 1. Cardiac Ultrasound In The Subxiphoid View
    2. Figure 2. Cardiac Ultrasound In The Apical 4-Chamber View
    3. Figure 3. Cardiac Ultrasound In The Parasternal Long-Axis View
    4. Figure 4. Cardiac Ultrasound In The Parasternal Short-Axis View, Mitral Valve Level, In The Cardiology Orientation
    5. Figure 5. Pericardial Effusion Seen Through The Subxiphoid Window
    6. Figure 6. Pericardial Effusion Seen Through The Parasternal Long-Axis View
    7. Figure 7. Right Upper Quadrant View In The FAST Examination
    8. Figure 8. Left Upper Quadrant View In The FAST Examination
    9. Figure 9. Pelvic View In The FAST Examination
    10. Figure 10. Subxiphoid Cardiac View In The FAST Examination
    11. Figure 11. Lung View In The E-FAST Examination For Assessment Of Pneumothorax
    12. Figure 12. Skull Fracture On Ultrasound
    13. Figure 13. Pneumonia On Ultrasound With Shredded Pleura And Subpleural Consolidations
    14. Figure 14. Pneumonia On Ultrasound With Subpleural Consolidations
    15. Figure 15. Inferior Vena Cava In The Long Axis
    16. Figure 16. Inferior Vena Cava And Aorta In The Short Axis
    17. Figure 17. Appendictis On Ultrasound
    18. Figure 18. Appendictis With An Appendicolith On Ultrasound
    19. Figure 19. Intussusception On Ultrasound
    20. Figure 20. Normal Pylorus On Ultrasound
    21. Figure 21. Intrauterine Pregnancy On Ultrasound
13. Associated Resources
    1. Link To Cardiac Ultrasound Video
    2. Link To Video Of Trauma Ultrasound Of The Peritoneum
    3. Link To Video Of Point-Of-Care Ultrasonography For Diagnosis Of Pneumonia
14. Acknowledgement
15. References

Abstract

Emergency ultrasound is performed at the point of care to answer focused clinical questions in a rapid manner. Over the last 20 years, the use of this technique has grown rapidly, and it has become a core requirement in many emergency medicine residencies and in some pediatric emergency medicine fellowships. The use of emergency ultrasound in the pediatric setting is increasing due to the lack of ionizing radiation with these studies, as compared to computed tomography. Utilizing diagnostic ultrasound in the emergency department can allow clinicians to arrive at a diagnosis at the bedside rather than sending the patient out of the department for another study. This issue focuses on common indications for diagnostic ultrasound, as found in the pediatric literature or extrapolated from adult literature where pediatric evidence is scarce. Limitations, current trends, controversies, and future directions of diagnostic ultrasound in the emergency department are also discussed.

Case Presentations

You are working in a small community ED on an overnight shift. It is 2:00 AM, and an 8-year-old boy with no significant past medical history arrives with his parents after 2 days of abdominal pain and vomiting that has worsened over the past 24 hours. They deny fever or a change in his bowel movements. His triage vital signs are normal, other than a temperature of 37.8°C. He is lying on the stretcher, reluctant to move. His head and neck, cardiac, respiratory, and skin examinations are all normal. His abdominal examination reveals a soft abdomen, with tenderness at McBurney point and a positive Rovsing sign. You believe your patient has appendicitis. Your practice is to send the patient for an ultrasound as the first diagnostic test; however, ultrasound is not available overnight at your hospital. You want to avoid radiation exposure for this child, but you also want to quickly disposition the patient to the operating room if appendicitis is confirmed. You order basic laboratory work, a urinalysis, intravenous morphine, ondansetron, and normal saline to relieve the patient’s symptoms. You consider performing a bedside emergency ultrasound…

While discussing the plan for an ultrasound to assess for appendicitis in your patient, you are called overhead to the resuscitation room. On arrival, visibly concerned EMTs are placing a 3-year-old girl on a stretcher. She is in extreme respiratory distress. Her parents say that she had a “cold” for 10 days. Over the last several days, she developed progressively increasing difficulty breathing. For the last 2 days, she has been crying more than usual and today had a sudden increase in respiratory distress as well as increasing lethargy. Her parents called the ambulance when they found her difficult to arouse. On your initial assessment, you note that she only moans in response to stimulation, and she has markedly increased work of breathing, with intercostal retractions and nasal flaring, despite being on a nonrebreather mask. Her peripheral pulses are weak and thready, and her capillary refill is 5 seconds. She is placed on a cardiac monitor, and has the following vital signs: temperature, 37.3°C; blood pressure, 50/20 mm Hg; heart rate, 170 beats/min; respiratory rate, 50 breaths/min; and oxygen saturation, 98% on nonrebreather mask. The nurses place 2 intravenous lines and draw laboratory tests. The physical examination reveals clear lungs. You cannot appreciate heart sounds, but note jugular venous distention and hepatomegaly. You order a portable chest x-ray, ECG, and a 20-cc/kg bolus of normal saline. You consider cardiac tamponade as your most likely diagnosis and would like an echocardiogram performed as soon as possible to confirm the diagnosis. However, you also believe the patient may be too unstable to wait for the on-call cardiologist to arrive. While the fluid bolus is being administered and you are awaiting the other studies, you consider an emergency ultrasound for immediate diagnosis.

Introduction

Over the last 2 decades, the use of ultrasound by emergency clinicians, as well as other specialists at the point of care, has become increasingly common. Emergency ultrasound can be used as a diagnostic test and also to visualize anatomy for procedural guidance. It allows the emergency clinician to rapidly rule in or rule out disease processes and guide ongoing investigation and management of patients in the emergency department (ED). It is a skill required by the Accreditation Council for Graduate Medical Education for emergency medicine residency training,¹ and it is supported by many organizations, including the American Medical Association, the American Academy of Pediatrics, the American College of Emergency Physicians (ACEP), the American Board of Emergency Medicine, and the American Institute for Ultrasound in Medicine.

Pediatric emergency ultrasound has been slower to progress than adult emergency ultrasound. Of the 95 emergency ultrasound fellowships currently listed on the Emergency Ultrasound Fellowships website (www.eusfellowships.com), only 5 are pediatric-specific. However, the pediatric patient is arguably more suited for emergency ultrasound than the adult patient. Children generally have a smaller body habitus than adults and, therefore, less tissue for the ultrasound beams to penetrate. This often leads to clearer images of the different organ systems, which should yield better diagnostic accuracy. There are sparse data to support this, however, due to a lack of comparative studies of the populations. The largest meta-analyses pool together adult and pediatric patients without assessing the diagnostic accuracy of this testing separately in adults and children, even for the most basic emergency ultrasound technique, the focused assessment with sonography in trauma (FAST) examination.^2-7

Children are an ideal target population in which to increase the use of emergency ultrasound. Exposure to ionizing radiation from computed tomography (CT) scans may lead to an increased incidence of cancer.^8-10 Pediatric cells divide at a faster rate than adult cells, and, therefore, pediatric patients have a greater risk of harm from ionizing radiation as compared to adults. The number of CT scans performed overall has increased 5-fold over the last 20 years, and it is widely believed that we will see an increased incidence of cancer directly linked to medical imaging.¹¹ One large retrospective epidemiological study found a small, but significant, increase in cancer related to CT scanning in the first decade of life. The study predicted that there would be 2 cases of excess cancer (cancer that would not have occurred without the CT scans) per 10,000 CT scans in the decade following the first CT scan in patients aged < 10 years.¹² With an estimated 4 million CT scans being completed annually in pediatric patients,¹³ it is incumbent on healthcare providers to find alternate diagnostic methods for these patients.

Ultrasound has been shown to have a high diagnostic accuracy for many pathologies, without the associated risks of ionizing radiation. Diagnostic ultrasound in pediatric patients has been traditionally in the domain of pediatric radiologists and technicians who are skilled in the interpretation of ultrasound for pediatric-specific pathologies. Many centers do not have access to pediatric radiologists or do not have access to pediatric ultrasound during evening and night hours. These centers generally transfer pediatric patients who need medical and surgical care to tertiary care centers with pediatricians and pediatric surgeons. If the emergency clinician can make or rule out a diagnosis at the bedside, transfer to the appropriate facility can be expedited and unnecessary transfers avoided.

Critical Appraisal Of The Literature

Risk Management Pitfalls In The Use Of Diagnostic Ultrasound To Evaluate Pediatric Patients In The Emergency Department

1. “While caring for a child with possible intussusception, I couldn’t obtain a good view of the abdomen on my emergency ultrasound, so I assumed it was not intussusception, and I discharged the patient.”
   Emergency ultrasound is meant to answer yes or no questions. If your examination is technically inadequate or if you are unsure that you adequately answered your clinical question based on the images, then order a radiology-performed ultrasound or another available imaging study.
2. “I did not see any abnormalities on my emergency ultrasound, so I told the patient’s parents everything was normal, and that she could be discharged home.”
   Emergency ultrasound is meant to be a limited study to answer focused clinical questions. It is not meant to be a comprehensive organ system assessment. Patients and caregivers should understand the limited nature of the bedside ultrasound.
3. “The patient had a pericardial effusion and was tachycardic. However, I saw no signs of cardiac tamponade on my emergency ultrasound, so I did not consult cardiology or cardiac surgery.”
   Cardiac tamponade is a clinical diagnosis. If the patient has a pericardial effusion and is unstable, then cardiac tamponade should be considered, despite the lack of ultrasound findings of tamponade.
4. “The FAST examination was negative, so I ruled out serious abdominal trauma and discharged the patient.”
   The FAST examination is a poorly sensitive test and cannot be used to rule out intra-abdominal injuries. Children often have organ injury without evidence of free intraperitoneal fluid.
5. “The appendix appeared normal on ultrasound, so I told the patient’s parents that it was not appendicitis and discharged him.”
   While ultrasound is quite specific for appendicitis, it is not sensitive enough to rule out this high-risk condition. Also, visualization of the normal appendix challenges even experienced sonographers and radiologists, so misdiagnosis remains a possibility. While clinical pathways combining risk scoring and ultrasound are being developed, this has yet to be repeated in multiple populations and cannot be relied upon. However, one can use ultrasound to rule in appendicitis.
6. “In a pediatric patient with cardiac arrest, there was no evidence of cardiac activity on ultrasound, so I recommended discontinuation of resuscitation efforts.”
   While there are data in adults that ultrasound can be used as a prognostic indicator in cardiac arrest, there are insufficient data in children for it be used alone to prognosticate outcomes in pediatric cardiac arrest.
7. “The child presented with fever, cough, and mild tachypnea for 5 days. My emergency ultrasound did not reveal pneumonia, so I sent the patient home without antibiotics.”
   While ultrasound is more specific than CXR, it is not as sensitive as CXR, as it can only evaluate pneumonias that reach the pleural line. If only lung ultrasound is employed, patients and clinicians should be aware of the sensitivity of that testing and ensure close follow-up.
8. “In my patient with gastroenteritis, the IVC ultrasound was normal, so I decided not to give intravenous fluids.”
   There are insufficient data to rely only on the IVC ultrasound for volume assessment. Patients may have a dilated IVC due to other diseases (such as pulmonary hypertension) and still require intravenous fluids for treatment of dehydration. Rather, the ultrasound can be used as a data point, combined with other clinical elements in the evaluation of the possibly dehydrated child.
9. “While evaluating a child with right upper quadrant pain, I performed an emergency ultrasound that did not reveal any gallbladder pathology, so I told the parent it could not be cholecystitis, and I discharged the patient.”
   The minimal data we have suggest that ultrasound is poorly sensitive for biliary tract disease in children, even when performed by radiologists. If highly suspected, other testing or consultation should be pursued.
10. “Despite significant testicular pain and swelling, the testicular ultrasound was normal, so I discharged the patient.”
    Intermittent testicular torsion may present with a normal ultrasound, whether the radiologist or the emergency clinician performs the ultrasound. High clinical suspicion should prompt urology consultation in the ED, even if the ultrasound does not show testicular torsion.

References

Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.

To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study will be included in bold type following the references, where available. The most informative references cited in this paper, as determined by the author, will be noted by an asterisk (*) next to the number of the reference.

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