IOTW 1/25/21

58 y/o M p/w chest pain and dyspnea

  1. What are the four primary sonographic signs of cardiac tamponade?
    • Pericardial effusion. Measure the largest pocket during diastole. Large is >2.0 cm. Moderate is 1.0 – 2.0 cm. Small is <1.0 cm. Trivial is only visible during systole. Important to remember that the rate of accumulation is more important than the actual size in developing tamponade.
    • Right-sided chamber collapse. In normal physiology, the right ventricle contracts during systole and the right atrium contracts during diastole. As an effusion accumulates, the intrapericardial pressure may overwhelm the intracardiac pressure. This will first lead to right atrial systolic collapse and may progress to the later finding of right ventricular diastolic collapse.
    • Plethoric IVC. As with any obstructive cardiac process, there will be loss of respiratory variation of the IVC.
    • Doppler surrogate of pulsus paradoxus. This can be assessed by measuring the inflow velocities of the mitral and/or tricuspid valve. The concept of pulsus paradoxus is that there is an exaggeration of the normal respiratory variation of blood pressure during tamponade physiology when intracardiac volume competes for space with the pericardial sac. This ventricular interdependence during inspiration will cause a decrease in mitral inflow velocity variation >25% and an increase in tricuspid inflow variation >40%.
  2. What intervals are represented by labels “A” and “B”?
    • The Y-axis of M-mode corresponds to depth, thus A represents the right ventricle with layer of pericardial effusion and B represents left ventricle with mitral valve.
  3. Which phases of the cardiac cycle are represented by labels “C” and “D”?
    • The X-axis of M-mode corresponds to time, thus C represents ventricular diastole where the first spike is the E-wave (early diastolic filling) and the second smaller spike is the A-wave (atrial kick). D represents the period of ventricular systole. It is important to recognize labels A-D because you can observe the variation in RV size during diastole to determine if there is true RV diastolic collapse. In this case, there is some RV collapse, however it is primarily in systole and does not overlap significantly with diastole.
  4. In the clinical setting of cardiac tamponade, how much variation throughout the respiratory cycle would you expect to see on the structure labeled “E”?
    • This represents the IVC and you would expect it to be plethoric with minimal to no respiratory variation. This carries a 95-97% sensitivity for cardiac tamponade.
  5. What is being measured in the diagram labeled “F”? Does this represent cardiac tamponade?
    • This is how the measurement of mitral inflow variation is performed. Note the doppler gate in the left ventricle near the mitral valve on the apical-4 view. The velocities of the tallest and shortest E-waves are measured. The percent decrease between 102 cm/s and 83 cm/s is approximately 20%, which is less than 25% and not quite suggestive of cardiac tamponade.

IOTW 12/14/20

65 y/o F p/w fever and hypoxia

  1. Name the structures indicated by labels “A, B, C, D, and E.”
    • A – Diaphragm
    • B – Liver
    • C – Spleen
    • D – Rib with posterior shadowing
    • E – Pleura
  2. What is indicated by label “F”? What type of artifact causes this? What does it signify?
    • B-Lines which are caused by a type of reverberation artifact. This typically signifies thickened or fluid-filled interlobular septa. While occasional B-Lines in the lung bases can sometimes be a normal finding (especially in elderly populations), 3 or more per lung field is usually pathological and consistent with an interstitial syndrome. This can be seen in almost any interstitial process such as pulmonary edema, pneumonia, lung contusions, and masses, for example.
  3. What sign is label “H” and what does it mean?
    • Spine sign. In normal lung, vertebral bodies on ultrasound should terminate at the level of the diaphragm and not be visualized above due to the inability of ultrasound waves to transmit through air. The presence of a fluid collection in the lung, however, will act as an acoustic medium for the transmission of ultrasound waves allowing visualization of the spine above the diaphragm as seen in the images above. This is non-specific for determining the type of fluid collection, as this can be seen with pleural effusions, hemothorax, and even consolidations.
  4. What is indicated by label “G” and what are the two different types?
    • Air bronchograms. They are air-filled areas of the bronchial tree which are visualized in the presence of fluid-filled alveoli which act as an effective acoustic window. There are 2 types of sonographic air bronchograms:
      • Static – These will remain fixed in position during the respiratory cycle. This indicates air trapped in small bronchi caused by complete bronchial obstruction from atelectasis.
      • Dynamic – These will exhibit small movements with respiration indicating partial bronchial obstruction from fluid mixed with air. This finding typically represents pneumonia.
  5. Name four sonographic lung findings that suggest pneumonia as the diagnosis.
    • B-Lines – often seen with small areas of subpleural consolidation. In early stages of pneumonia, only some alveoli will be fluid-filled and can lead to a patch of focal B-Lines.
    • Hepatization – this refers to the solid “liver-like” sonographic appearance of lung as it becomes inflamed and filled with purulent fluid. This can be seen in consolidation or atelectasis.
    • Shred sign – this appears as an irregularity of the pleural interface in the setting of small areas of consolidated lung. These areas abut the pleural surface causing the “shredded” appearance on ultrasound.
    • Dynamic air bronchograms – as discussed in question 4, this finding has been shown to have a 94% specificity and 97% positive predictive value for pneumonia as the cause of the consolidation.
    • Color doppler can also be used which would demonstrate the pulmonary vasculature in areas of consolidation. A concomitant parapneumonic effusion with echogenic debris can suggest empyema.

IOTW 11/30/20

18 y/o M p/w chest and abdominal pain s/p fall from motorcycle the night prior

  1. Which FAST exam view above does NOT contain free fluid?
    • The Subxiphoid view does NOT contain free fluid. All three other views are positive.
  2. The primary survey of ATLS follows the “ABCDE” protocol. Which part of the primary survey does the FAST exam further assess: A, B, C, D, or E?
    • C – Circulation. An Extended-FAST (E-FAST) would also further assess B – Breathing.
  3. Can you accurately name what each arrow is depicting in the images above labeled A-L?
    • A – Liver
    • B – Free fluid in Morrison’s Pouch
    • C – Rib shadow artifact
    • D – Spleen
    • E – Left subdiaphragmatic free fluid
    • F – Left hemidiaphragm
    • G – Urinary bladder in sagittal view
    • H – Pelvic free fluid
    • I – Intestines
    • J – Right ventricle
    • K – Left ventricle
    • L – Pericardium
  4. What is the minimum amount of free fluid that the literature suggests can be detected on a FAST exam?
    • It was suggested that a minimum of 500 mL of free fluid could be detected on a FAST exam. However, as ultrasound imaging technology and operator technique improves, newer literature suggests that as little as 100 mL of free fluid can be detected.
  5. If the patient in the above scenario had unstable vital signs, do ATLS guidelines recommend the next step to obtain a CT scan or to activate the OR? What if the patient had stable vital signs?
    • As per ATLS, an unstable patient with a traumatic mechanism of injury and a positive FAST exam should go directly to the OR for laparotomy. A stable patient with a traumatic mechanism of injury and a positive FAST exam should receive a CT scan.
  6. Does a positive FAST exam differentiate what type of fluid is present?
    • No. Ascites and blood, for example, may have a similar appearance on ultrasound. In certain settings, such as trauma or an unstable patient, the fluid should be assumed to be blood until proven otherwise.
  7. Does a positive FAST exam reliably identify the source of bleeding?
    • No. Free fluid in any quadrant can represent blood that has pooled from a different area.
  8. Where does free fluid tend to initially accumulate in the RUQ view? What about in the LUQ view?
    • In the RUQ view, free fluid most often will be initially visible in the paracolic gutter (liver tip and inferior pole of kidney). In the LUQ view, free fluid most often will be initially visible in the subdiaphragmatic space above the spleen. Be sure to include everywhere from diaphragm to paracolic gutter in both views because free fluid can hide in variable locations.

IOTW 11/23/20

67 y/o F p/w RUQ pain

  1. What are the three structures that compose the portal triad?
    • Portal vein, hepatic artery, and common bile duct. The common bile duct will not exhibit flow when evaluated with color doppler.
  2. Which structure is indicated by label “A”?
    • The common bile duct. Note the absence of flow with color doppler.
  3. What is the name of the artifact indicated by label “B”?
    • Acoustic shadowing. Ultrasound waves are absorbed by a solid structure or reflected off of air, causing “clean” or “dirty” shadowing, respectively.
  4. What is the normal diameter of structure “A”? What about if the patient is post-cholecystectomy?
    • The CBD should measure <6 mm in diameter and the upper limit increases by 1 mm per decade after age 60. Post-cholecystectomy CBD may measure up to 10 mm (1 cm) in diameter. Be sure to measure from inner wall to opposing inner wall in a perpendicular fashion.
  5. What is the diagnosis hinted at by label “C”?
    • Choledocholithiasis. The CBD is grossly enlarged and measures about 9-10 mm in diameter when compared with the scale on the right-hand side of the screen. Label “C” indicates a visualized stone within the CBD distally which appears as an echogenic rounded focus with shadowing.
  6. Do these images suggest the presence of concomitant acute cholecystitis?
    • No. Sonographic evidence of cholecystitis includes stone in neck (SIN sign), anterior gallbladder wall thickening, pericholecystic fluid, gallbladder hydrops, and sonographic Murphy’s sign, none of which are present. There are numerous small gallstones within the gallbladder, however, which should at least raise suspicion for other biliary tract obstruction.
  7. Which diagnosis would you be most concerned about if the patient exhibited signs of infection?
    • Ascending cholangitis. The classic Charcot’s Triad (fever + jaundice + RUQ pain) only occurs in ~50% of patients and the classic Reynold’s Pentad (triad + altered mental status + hypotension) only occurs in <5%. In elderly patients, hypotension may sometimes be the only presenting sign, so a high index of suspicion must be maintained. If the diagnosis is likely, patients should be treated aggressively for sepsis with fluid resuscitation and antibiotics targeted at organisms such as E. coli, Enterococcus, Bacteroides, Clostridium, and even MRSA in severe cases. The case should be coordinated with gastroenterology and general surgery for ERCP and cholecystectomy to achieve source control and biliary decompression.

IOTW 11/10/20

28M p/w biliary colic however reports PMHx of “dilated heart”. Bedside ECHO was performed…

  1. What are some EKG findings associated with the suspected diagnosis?
    • In the setting of hypertrophic cardiomyopathy, EKGs may often be nonspecific or normal. However, you may see a high voltage or LVH pattern and deep narrow “needle-like” Q waves in the inferolateral leads. There may also be deep T-wave inversions in the anterolateral leads.
  2. What LV wall thickness supports the diagnosis?
    • Unexplained wall thickness >1.5 cm in any myocardial segment. A septal:posterior wall thickness ratio can be measured. An abnormal ratio is >1.3 in normotensive patients and >1.5 in hypertensive patients. The ratio in the image above comes out to (3.1 cm/1.8 cm=) ~1.7 which is abnormal and should prompt further evaluation. Asymmetric septal hypertrophy may be present. In addition, the LV outflow tract diameter can be measured in the parasternal long view just proximal to the aortic valve to assess for obstruction. The LVOT normally measures 1.6 – 2.4 cm.
  3. What features of the mitral valve are associated with this?
    • Mitral regurgitation is sometimes present. You may also assess for systolic anterior motion (SAM) of the mitral valve to help assess for obstruction. To do this you would obtain an M-Mode waveform through the anterior mitral valve leaflet in parasternal long view similar to how you would assess for EPSS. The mitral valve would exhibit anterior excursion toward the interventricular septum during systole if this was present.
  4. If this patient presents in decompensated CHF, what are some considerations in the management in regards to…
    • Administering IV fluids?
      • Volume loading is essential to increase preload and you should be sure to adequately fluid resuscitate prior to considering pressors in order to avoid worsening of the LV outflow tract obstruction. Monitor carefully for signs of fluid overload.
    • Intubation?
      • If it is absolutely necessary and cannot be avoided, you want to take all precautions to maintain preload. Push dose phenylephrine should be mixed and readily available (1 mL of 10 mg/mL phenylephrine in 100 mL NS = 100 mcg/mL; may use 1-2 mL (100-200 mcg) q2-5 min). BVM ventilations should not be aggressively performed. Avoid high airway pressures.
    • Managing tachycardia?
      • Beta blockers are the mainstay especially if angina or dyspnea present. You can titrate to a resting heart rate of 60 bpm. Use with caution if there is sinus bradycardia or conduction abnormality. Verapamil is another option. You must avoid vasodilators such as nitrates and dihydropyridine CCBs such as nifedipine. Do not give digitalis. Have a low threshold to cardiovert if needed to maintain sinus rhythm, for example if there is atrial fibrillation.
    • Choice of vasopressors?
      • If hypotensive and decision is made to initiate pressors, goal is to increase afterload. Phenylephrine is probably the best pressor to start with and consider vasopressin if it is maxed and a second pressor is needed. To increase efficacy of your pressors, attempt to fix any acidosis if present. AVOID positive intotropes such as dobutamine, norepinephrine, epinephrine, and dopamine.
  5. What is the definitive treatment of this condition?
    • While an ICD +/- AV sequential pacing may be used to treat ventricular dysrhythmias, the definitive treatment of LV outflow tract obstruction is myomectomy or resection of outflow tract.
  6. If the patient cannot be admitted, what discharge instructions should be provided?
    • Important to avoid exertion. May be started on beta-blocker from ED while pending cardiology appointment and follow-up comprehensive echo.