PoCUS in Pericardial Effusion

Medical Student Clinical Pearl – October 2019

 

Alex Pupek

Faculty of Medicine
Dalhousie University
CC4
Class of 2020

Reviewed and Edited by Dr. David Lewis

 


Case

A 70F with a history of bladder CA, HTN and 4.9cm AAA presented to the Emergency Department (ED) and was Triaged as Level 3 with a chief complaint of generalized weakness. Initial assessment was significant for hypotension and low-grade fever with dysuria elicited on history; she was started on Ceftriaxone with a working diagnosis of urosepsis. Bloodwork and imaging studies were sent to rule out other potential sources of infection.

She had a mild leukocytosis of 12.4, pH of 7.23 and a lactate of 5.0. Point-of-care urinalysis was unremarkable. The chest x-ray revealed an enlarged cardiothoracic ratio of 0.62 compared to 0.46 ten months previously, concerning for a pericardial effusion.

Upon reassessment, the patient appeared unwell with slight mottling to the skin, cool extremities and tenuous blood pressure; point of care ultrasound revealed a large pericardial effusion.  Interventional cardiology was paged; the patient was moved to the trauma area and an emergent pericardiocentesis was performed: 360cc of bloody fluid was removed. The pericardial drain was left in situ.

Post-procedure bloodwork included a troponin of 216 and CK of 204. The patient was admitted to the Cardiac Care Unit and discharged within a week’s time.

 


Pericardial Effusions and The Role of Point-of-Care Ultrasound (POCUS)

The normal pericardial sac contains up to 50 mL of plasma ultrafiltrate [1]. Any disease affecting the pericardium can contribute to the accumulation of fluid beyond 50mL, termed a pericardial effusion. The most commonly identified causes of pericardial effusions include malignancy and infection (Table 1).

 

Table 1 – UpToDate, 2019 – Diagnosis and Treatment of Pericardial Effusions


 

Evaluation of the pericardium with point-of-care ultrasound includes one of four standard views: parasternal long axis, parasternal short axis, subxiphoid and apical (Figure 1). A pericardial effusion appears as an anechoic stripe or accumulation surrounding the heart. Larger effusions may completely surround the heart while smaller fluid collections form only a thin stripe layering out posteriorly with gravity. Seen most commonly post-cardiac surgery, pericardial effusions may be loculated and compress only a portion of the heart. [1,2] (Table 2)

Figure 1[1]


Table 2 [2]


 

Both the pericardial fat pad and pleural effusions can be mistaken for pericardial effusions. The parasternal long-axis view is most helpful to accurately define the effusion with the descending aorta, posterior to the mitral valve and left atrium, serving as a landmark: the posterior pericardial reflection is located anterior to this structure. Fluid anterior to the posterior pericardial wall is pericardial, whereas a pleural effusion will lie posterior. The pericardial fat pad is an isolated dark area with bright speckles, located anteriorly; unlike fluid, it is not gravity dependent. Rather than competing with the cardiac chambers for space within the pericardial sac, the fat pad moves synchronously with the myocardium throughout the cardiac cycle. [1,2] (Figure 2)

Figure 2[1]


A pericardial effusion discovered on POCUS in the ED may be mistaken for tamponade, leading to inappropriate and invasive management in the form of pericardiocentesis.[2]

Patient tolerance of pericardial effusions depends on the rate by which they accumulate. As little as 150-200 mL of rapidly accumulating effusion can cause tamponade whereas much larger amounts of slowly accumulating fluid can be well tolerated. Pericardial effusions formed gradually are accommodated by adaptations in pericardial compliance. A tamponade physiology is reached once the intrapericardial pressure overcomes the pericardial stretch limit.[2] (Figure 3)

Figure 3[2]


The core echocardiographic findings of pericardial tamponade consist of:

  • a pericardial effusion
  • diastolic right ventricular collapse (high specificity)
  • systolic right atrial collapse (earliest sign)
  • a plethoric inferior vena cava with minimal respiratory variation (high sensitivity)
  • exaggerated respiratory cycle changes in mitral and tricuspid valve in-flow velocities as a surrogate for pulsus paradoxus

In the unstable patient with clinical and echocardiographic findings of tamponade, an emergent pericardiocentesis is indicated.[2]

A retrospective cohort study of non-trauma emergency department patients with large pericardial effusions or tamponade, ultimately undergoing pericardiocentesis, found that effusions identified by POCUS in the ED rather than incidentally or by other means saw a decreased time to drainage procedures, (11.3 vs 70.2 hours, p=0.055).[3]

Point of care ultrasound is a valuable tool during the initial evaluation of the undifferentiated hypotensive emergency department patient but should be interpreted judiciously and within clinical context to avoid unnecessary emergency procedures.


Additional Images

From GrepMed


 

echocardiogram-pericardial-tamponade-alternans-effusion

 


References

  1. Goodman, A., Perera, P., Mailhot, T., & Mandavia, D. (2012). The role of bedside ultrasound in the diagnosis of pericardial effusion and cardiac tamponade. Journal of emergencies, trauma, and shock, 5(1), 72.
  2. Alerhand, S., & Carter, J. M. (2019). What echocardiographic findings suggest a pericardial effusion is causing tamponade?. The American journal of emergency medicine, 37(2), 321-326.
  3. Alpert, E. A., Amit, U., Guranda, L., Mahagna, R., Grossman, S. A., & Bentancur, A. (2017). Emergency department point-of-care ultrasonography improves time to pericardiocentesis for clinically significant effusions. Clinical and experimental emergency medicine, 4(3), 128.

 

Continue Reading

Pediatric Hip PoCUS

Pediatric Hip PoCUS

PoCUS Pearl

Dr. Sultan Ali Alrobaian

Dalhousie EM PoCUS Fellowship

Saint John, NB

@AlrobaianSultan

 

Reviewed and Edited by Dr. David Lewis


 

Case:

A 5 year old healthy boy, came to ED with history of limping since waking that morning. He had worsening right hip discomfort. No history of trauma. He had history of cold symptoms for the last 3 days associated with documented low grade fever.

On physical examination, he looked uncomfortable and unwell looking, he had temperature of 38.1 C, HR 130, BP 110/70, RR 20 and O2 saturation of 98% on RA. He was non-weight-bearing with decreased ROM of right hip because of pain.

Pelvis x-ray was unremarkable, he had WBC of 14.4 x 103  and CRP of 40 .

PoCUS of the right hip was performed.


 

Pediatric Hip Ultrasound

Ultrasonography is an excellent modality to evaluate pathologies in both the intra-articular and extra-articular soft tissues including muscles, tendons, and bursae. PoCUS to detect hip effusion can serve as an adjunct to the history and physical examination in case with hip pain.  It is easily accessible, no radiation exposure and low cost.

Technique:

The child should be in supine position. Expose the hip with drapes for patient comfort. If the patient will tolerate it, position the leg in slight abduction and external rotation. A high frequency linear probe is the preferred transducer to scan the relatively superficial pediatric hip, use the curvilinear probe if increased depth is required.

With the patient lying supine, identify the greater trochanter on the symptomatic hip of the patient. Place the linear probe in the sagittal oblique plane parallel to the long axis of the femoral neck (with the indicator toward the patient’s head).

If the femoral neck cannot easily be found, it can be approached using the proximal femur. Place the probe transversely across the upper thigh. Identify the cortex of the proximal femur and then move the probe proximally until the femoral neck appears medially, then slightly rotate the probe and move medially to align in the long axis of the femoral neck.

Assistance is often required from a parent who may be asked to provide reassurance, apply the gel and help with positioning.

Both symptomatic and asymptomatic hips should be examined.

Negative hip ultrasound in a limping child should prompt examination of the knee and ankle joint (for effusion) and the tibia (for toddler’s fracture)

Hip X-ray should be performed to rule out other causes (depending on age – e.g. Perthes, Osteomyelitis, SCFE, Tumour). Limb X-ray should be performed if history of trauma or NAI.

 

Anatomy of the Pediatric Hip:

The ED Physician should readily identify the sonographic landmarks of the pediatric hip. These landmarks include the femoral head, epiphysis and neck, acetabulum, joint capsule and iliopsoas muscle and tendon.

 

A normal joint may have a small anechoic stripe (normal hypoechoic joint cartilage) between cortex and capsule. This will measure less than 2mm and be symmetrical between hips.

 

Ultrasound Findings:

Measure the maximal distance between the anterior surface of the femoral neck and the posterior surface of the iliopsoas muscle. An effusion will result in a larger anechoic stripe (>2mm) that takes on a lenticular shape as the capsule distends. Asymmetry between hips is confirmatory. Synovial thickening may also be visualized.

FH- Femoral Head, S- Synovium, E – Effusion, FN – Femoral Neck

Criteria for a pediatric hip effusion is:

  • A capsular-synovial thickness of 5 mm measured at the concavity of the femoral neck, from the anterior surface of the femoral neck to the posterior surface of the iliopsoas muscle
  • OR a 2-mm difference compared to the asymptomatic contralateral hip

Right hip effusion, normal left hip, arrow heads – joint capsule, IP – iliopsoas


Interpretation

PoCUS has high sensitivity and specificity for pediatric hip effusion.

  • —
  • Sensitivity of 90%
  • Specificity of 100%
  • Positive predictive value of 100%
  • Negative predictive value of 92%

 

PoCUS cannot determine the cause of an effusion. It cannot differentiate between transient synovitis and septic arthritis. Diagnosis will be determined by combining history, pre-test probability, examination, inflammatory markers and PoCUS findings. If in doubt, septic arthritis is the primary differential diagnosis until proven otherwise.

Several clinical prediction algorithms have been proposed. This post from pedemmorsels.com outlines these nicely:

 

Septic Arthritis

 

 


 

Back to our case:

Ultrasonography cannot definitively distinguish between septic arthritis and transient synovitis, the ED physician’s concern for septic arthritis should be based on history, clinical suspicion and available laboratory findings.

The patient was diagnosed as case of septic arthritis. The patient received intravenous antibiotics empirically. Pediatric orthopedic consultation was obtained, and ED arthrocentesis was deferred as the patient was immediately taken to the operating room for hip joint aspiration and irrigation, confirming the diagnosis.


 

References

 

Continue Reading