Answer: C or D - Consolidation L base with small associated effusion, in keeping with atelectasis or pneumonia

We see here that most of the lung is well-aerated. There are A-lines throughout the anterior and lateral lung fields, and at the R base.

At the left base we see a consolidation with a small associated effusion. It can be difficult (and often impossible) to tell on ultrasound whether consolidations represent atelectasis or pneumonia. There are some clues that may be helpful - bilateral symmetrical consolidations with small associated simple effusions are consistent with atelectasis and are common in hospitalized bed-bound patients. In contrast, dynamic air bronchograms, an associated complex pleural effusion, or unilateral consolidations point more towards pneumonia. The tethering of the lung to the diaphragm is also, in our experience, more typically associated with inflammatory/malignant/infectious etiologies (rather than simple atelectasis), although there is no data that we’re aware of to back this up. For more on the distinction between pneumonia and atelectasis, see the linked screencast HERE.

In this case, the consolidation is unilateral and appears tethered to the diaphragm; however there are no dynamic air bronchograms, nor any complexity in the associated effusion. Other than fevers, the patient also did not have any symptoms suggestive of a pneumonia (no shortness of breath, no cough, saturations of 100% on room air). We therefore recommended close surveillance for signs of pneumonia, sputum cultures, and a low threshold to initiate antibiotic therapy. There was no drainable pleural effusion identified. The possible effusions suggested on CXR most likely represented the combination of the LLL consolidation, small effusion, and the elevated hemidiaphragm noted (with low lung volumes).

Answer: A - Yes

There are several ultrasound features of elevated intra-pericardial pressures that we can look for on POCUS.

Qualitatively, end-diastolic right atrial collapse (during atrial relaxation) will occur. While brief collapse is non-specific, RA collapse lasting >1/3 of the cardiac cycle is reported to be highly sensitive and specific for tamponade. As pressures increase further, RV free wall collapse during early ventricular diastole also becomes apparent. This is less sensitive, but more specific, than RA collapse; however, RV collapse may be absent in the presence of significantly elevated R-sided pressures or RVH. Note that it can be very helpful to slow your clips down to half speed to help discern in which part of the cardiac cycle chamber collapse is occurring – this was done using SonoClipShare online.

Quantitatively, the respiratory variation in the mitral and tricuspid inflows can be measured (not done in this case due to machine limitations). There are essentially the echocardiographic (and more accurate) correlate to the pulsus paradoxus on physical examination. Cutoffs for significant respiratory variation vary across different texts, but range from 25-30% for mitral inflows, and 40-60% for tricuspid inflows.

The IVC (discussed below) is useful to rule out elevated intrapericardial pressures if it is collapsible; but a plethoric IVC is non-specific and does not rule this in.

In these clips, there is an obvious pericardial effusion. This would be classified as a large pericardial effusion (>2cm when measured in diastole). We do see evidence of RA collapse (often described as the appearance of “an invisible person bouncing on a trampoline on the RA”); however, we don’t appear to see any RV diastolic collapse.

Answer: C - Unclear, need more information

This IVC was the subject of an interesting recent Twitter thread (linked here). Although there appears to be some respiratory change close to the cavo-atrial junction, the rest of the IVC remains plethoric. This raises the possibility that the observed changes are due to diaphragmatic contraction, rather than true IVC collapse. The ideal place to assess IVC changes has classically been touted as 1-2cm from the cavo-atrial junction; however, this teaching is changing as most experts believe that more distance is needed to avoid being fooled by changes related to the diaphragm (which can either cause tenting or collapse).

The most useful next step here would be to assess the IVC in short axis along its length. This second view is crucial in cases like this where there is suspicions that the long-axis view may be confounded. In this case, a short-axis view was done (but not clipped – crucial POCUS error!), which revealed a plethoric, non-varying IVC.

Finally, it is worth noting that there was very high pre-test probability for a plethoric IVC given the evidence of raised intra-pericardial pressures seen on focused cardiac ultrasound as noted above. The treating team was therefore very skeptical of the IVC changes noted in this clip, and wanted further information to be sure that it was a true finding.

Answer: C - It’s complicated

The most important point to emphasize here is that tamponade is not a binary diagnosis. Tamponade is characterized by the accumulation of pericardial fluid under pressure. Its hemodynamic consequences exist on a spectrum; patients with normal blood pressure may still have evidence of elevated intra-pericardial pressures, and may have some degree of compromised LV filling as a result. Though a patient may not be currently hypotensive and in extremis, they may still be experiencing reduced LV filling and negative hemodynamic effects.

This paper does a great job of explaining this and other common misconceptions around cardiac tamponade – it’s well worth a read. The diagram below is taken from the paper and illustrates the spectrum of hemodynamic abnormalities that may occur with tamponade.

Answer: C - Yes, for other reasons

As with the previous question – although the patient was not hypotensive, he was likely experiencing some degree of impaired cardiac output due to the elevated intrapericardial pressures. In addition, a couple factors led the team to push for a expedited pericardial drainage:

Firstly, the effusion had significantly increased in size since the initial imaging (CT scan). There was therefore significant concern that the patient could deteriorate quite quickly in the coming days/weeks if not drained, as he moved along the spectrum of negative hemodynamic effects.

Secondly, there remained diagnostic uncertainty with regards to the patient’s ongoing daily fevers. A sample of pericardial fluid would be helpful to look for other potential causes of the persistent fevers, which were multiple in such an immunocompromised patient (for example, pericardial TB, lymphoma, or incompletely treated pericardial histoplasmosis).