“This reflective writing piece was completed by Dr. Aashish Kalani upon completion of his recent CCUS block. For those of you unable to rotate with us, who have rotated but may have forgotten some things or for those who will someday rotate with us, read on – I think you’ll find value here!”
Rob Arntfield, MD, FRCPC, December 2018
Not all hyperdynamic hearts warrant IV fluids
The temptation when seeing hyperdynamic LV function is to provide IV fluid which may be a precarious one
The differential for hyperdynamic LV function is broad, including deranged metabolic states, infectious states, inflammatory states, and hypovolemia. Liberally providing IV fluids for hyperdynamic hearts may not correct some of these states and may drive iatrogenic volume overload which can carry a range of complications including lung injury, impaired mobility, and organ dysfunction. Combining the clinical picture, IVC status and lung profile should be combined with determination of hyperdynamic LV function to facilitate decision-making with regards to IV fluids and beyond.
More to B-lines than pulmonary edema
Bilateral B-line lung pattern has a large differential
Other than cardiogenic pulmonary edema, bilateral B-line pattern can be compatible with pneumonia, ARDS, interstitial lung disease and other conditions. Assessments of the pleural line, pulmonary parenchyma (including presence or absence of C-pattern), distribution of B-lines, cardiac status, and – of course – clinical status can help narrow down the etiology.
Cardiac output assessment is a more useful assessment of LV function compared to LVEF
Cardiac output calculations provide more accurate assessments of systemic perfusion
While more challenging to acquire accurately, cardiac output calculations incorporating LVOT diameter, HR, and LVOT VTI assessments take out complicating factors such as mitral regurgitation which can skew LVEF.
More to differentiating pneumonia from atelectasis than dynamic air-bronchograms
Dynamic air bronchograms are not terribly sensitive
Other lung ultrasound findings, such as absence of A-lines, hepatization, and ill-defined margins are some of the other of findings that can help support a diagnosis of pneumonia over atelectasis.
Findings to support diagnosis of a complicated pleural effusion
Typically loculations and septations are searched for to help diagnose complicated pleural effusions
Other signs are supportive as well, such as plankton sign (swirling debris in the pleural fluid that appear with respiratory motion). As well, complicated fluid may not always be anechoic but can be hyperechoic as well. Another useful finding is the hematocrit sign (demonstrating settling of fluid with increased echogenicity at the dependent area of the effusion where coagulated cells and other debris gather as a result of gravity)
Assessment of LV function should take heart rate into consideration
Increased heart rates can make the inexperienced ultrasonographer overestimate LV function
Slowing down the video clip during image interpretation can reveal underlying sluggish hearts. When slowing down the video clip, subjective assessments in addition to endocardial wall excursion, endocardial thickening and EPSS should be applied.
Quality of parasternal views in any given patient is inversely proportional to quality of subcostal views
Based on the natural axis of how the heart sits in the thoracic cavity, often if easy parasternal views are obtainable, the heart is sitting in a more superior and transverse orientation. This may mean that subcostal views will be more challenging in the same patient. The same goes for more inferior, longitudinally positioned hearts. Some patients of course have a panel of beautiful views but this “law” does help the junior ultrasonographer with trusting the skill development process.
Tips to optimize a cardiac image
Rather than adjusting the gain, dropping the dynamic range often provides better contrast of anechoic cavities with hyperechoic cardiac tissue
As well, rather than just adjusting the depth, modulating the sector width to encompass the heart but not entrap it can also help appraise relevant pathology at hand. Also sometimes hearts can be cut off axis which can over- or under-estimate cavitary size – rotating, tilting, and rocking movements as appropriate can help obtain a more comprehensive set of views after which the most accurate picture can be selected.
IVC diameter & variability with respiration – not as useful for assessing volume status and volume responsiveness as you may think
The literature for IVC assessment and its relationship to volume responsiveness and overall volume status is scarce and limited
It is especially fraught with peril to use IVC assessments in the spontaneously breathing patients to help make these decisions. Perhaps one applicable area of IVC assessment is in passively ventilated patients – distensibility >18% can support a strategy of volume resuscitation, combined with other parameters of course. Otherwise, IVC diameters at the extremes can be helpful – skinny IVCs with large respiratory variation can support plans for fluid resuscitation and plethoric IVCs with little-no respiratory variation should raise caution.
If someone offers you coffee, just take it!
By Derek Wu|2018-12-18T20:33:09+00:00December 18th, 2018|Creative, Electives|Comments Off on 10 Things I Learned on my POCUS Elective