key: cord-0722374-4ipyz2y1
authors: Zochios, V.; Charlesworth, M.
title: Protecting the right ventricle in COVID‐19 pneumonitis: a missing piece of the puzzle?
date: 2022-03-22
journal: Anaesthesia
DOI: 10.1111/anae.15720
sha: 710826d8540adbf05f4470bff23aca41e5daceb0
doc_id: 722374
cord_uid: 4ipyz2y1

nan

The right ventricle is non-geometric and its echocardiographic assessment is complex. A complete assessment takes account of size, global systolic function (several available methods), regional function (difficult), diastolic function (rarely performed), pulmonary artery systolic pressure and features of volume and pressure overload. Assessing size is best done qualitatively by first looking at whether the cardiac apex incorporates both the right and left ventricle, in which case dilation is at least moderate. Moderate to severe dilation can be seen when the ventricular septum is flattened or displaced towards the left ventricle. This is also a feature of pressure or volume overload. That there are several methods for assessing systolic function rightly suggests each approach has problems. The main issue is that, as well as its complex anatomy, the right ventricle contracts through longitudinal shortening rather than the radial contraction seen with the left ventricle. At the most basic level, systolic function can be qualitatively categorised as normal, impaired or severely impaired. The most used quantitative metrics are fractional area change (abnormal if < 35%) and tricuspid annular plane systolic excursion (abnormal if < 16 mm). Each approach, measurement and categorisation has associated flaws, which probably accounts for why the right ventricle is easy to overlook. Yet, one of the most useful measurements for use in clinical practice is the estimation of pulmonary artery systolic pressure, which is done by measuring tricuspid regurgitation jet velocity. Severe pulmonary hypertension is likely when regurgitant jet velocity is > 3.5 m.s -1 , and regular measurements can help titrate pulmonary vasodilators, sedation and respiratory support in ARDS.

There is an even greater limitation here, touched upon by Chotalia et al., and this is determining when is the right time to undertake echocardiography in ICU. This is a major limitation of the paper, because some examinations would have been done routinely whereas others will have been triggered by haemodynamic instability. In the absence of any clear guidance on this, we would simply argue we need to do it more and become better familiarised with the implications for clinical management. 

There is no universally accepted definition for acute right ventricular injury, and its diagnosis is more complex than assessing right ventricular performance. The problem is that accepted definitions focus on late-stage injury [3] , and what we really need is a way to identify early injury so that protective strategies can be employed before haemodynamic instability and multi-organ failure develop.

One way of doing this is by looking at how the right ventricle interacts with the pulmonary vasculature [4] . This is known as 'coupling', and is a mechanistically useful concept.

A dilated right ventricle in ARDS implies early yet potentially significant injury, which may yield systemic congestion and secondary organ injury [4] . Chotalia et al. showed that right ventricular dilatation, analogous to early injury, was associated with renal dysfunction and increased mortality [5] . Over half of those with the 'class 2' phenotype (isolated dilatation) required renal replacement therapy [1] . [7] . Due to the problems around echocardiographic assessment of the right ventricle in ARDS and timing, right ventricular injury might only be revealed late in the disease process by profound haemodynamic instability and even death. There should now be a shift towards more routine echocardiographic assessment, earlier identification of injury and protection. progression of lung and right ventricular injury, even when gas exchange is within acceptable parameters (Fig. 1 ) [9] [10] [11] [12] . Venopulmonary-arterial extracorporeal membrane oxygenation support from the outset in patients with severe COVID-19 refractory pneumonitis and evidence of right ventricular injury may confer a survival benefit [11, 12] . The 'signal' is a potential beneficial effect of early venopulmonary-arterial extracorporeal support, which could be attributed to right ventricular 'rest' at the initiation of extracorporeal support in selected patients. propose a multimodal diagnostic physiological approach to right ventricular assessment and risk stratification, which may have therapeutic relevance but needs to be prospectively validated in large patient cohorts. The key take-home message though is that we need to get better at echocardiography in ICU, perform it more regularly and use it to demonstrate, treat and monitor right ventricular injury earlier than we do currently.

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