Hot-off-the-Press Intensive Care Management of COVID-19: Recommendations
‘Management of Acute Respiratory Failure and Haemodynamics is key’
April 6th saw the publication in The Lancet of an overview of the broad challenges faced by the ICU community in COVID-19 patients. Turning our focus on to the clinical aspects it’s clear from this and other dialogue that this disease presents some clear differences when compared with other respiratory viruses. It’s striking that there seem to be many dilemmas to confront the clinician. Furthermore it’s hard not to conclude that one key requirement is for tight control of haemodynamic parameters.
For a little background, refer to the WHO-China Joint Mission review of 55924 laboratory-confirmed cases. 6.1% were identified as suffering from respiratory failure, shock and multiple organ dysfunction or failure. References suggest 10-30% of ICU patients suffer Acute Kidney Injury (AKI) and this figure is, at least anecdotally supported by reports coming out of major UK treatment centres.
Intervention in critically ill patients presenting with a novel disease carries its fair share of uncertainty. The critical care community is increasingly recognising a few defining principles that apply to COVID-19. Take ventilation, which is a complex subject all of its own. There seems broad agreement that the starting point in mild ARDS is non-invasive, with between one third and two thirds of Chinese patients having received non-invasive ventilation or high flow nasal cannula. That seems to be consistent with new findings in UK centres, CPAP on the ward, coupled with early (and repeated) “proning” sees to be effective (although prolonged CPAP usage in ICU is also being anecdotally associated with worse outcomes).
Up the treatment ladder, patients requiring mechanical ventilation seem to be more at risk in COVID-19 cases than in typical ARDS. The lungs in these ARDS patients are seemingly not as “stiff” as might normally be expected. They require less pressure (expressed as PEEP) than protocols would suggest. Indeed higher PEEP seems to be problematic. Again the UK experience agrees that a less aggressive PEEP strategy (in terms of timing and value) is favoured.
In summary, when it comes to lung function, it seems the conventional wisdom that focuses more on ventilation than perfusion (of the lungs) is somewhat turned on its head here. It’s more of a perfusion issue.
Getting the Fluid Balance right: Damned if you do, Damned if you don’t?
Perfusion means fluid and the implications of getting it wrong are significant. Conventional wisdom might see clinicians minimising fluids in order to keep the lungs dry and reduce incidence and severity of pneumonia. But the comparatively high rates of organ problems including AKI, coupled with the aforementioned lung perfusion issue (meaning blood supply to the lungs themselves) and reported myocardial problems, suggest that a restricted fluid regime is also inappropriate. As the paper proposes, “fluids should be administered cautiously, given the high incidence of myocardial dysfunction in COVID-19.”
The paper states; “A conservative or de-resuscitative fluid strategy, with early detection of myocardial involvement… and early use of vasopressors and inotropes are recommended”
Overlaying the conclusions of a selection of major UK centres reinforces the problem. The common conclusion is yet again that hypovolaemia should be avoided (to protect the kidneys) as should hypervolaemia.
Renal consequences of an acute Coronavirus infection are extensively reported, with significant therapeutic resource going into the “fixes” -filtration (CVVHF), heparin treatment and dialysis. The causes of these high levels of kidney injury are likely to be a combination of poor fluid control and a high incidence of kidney microthrombi in COVID-19 ARDS (also seen in the lungs).
By now it will surprise nobody that a recurring theme is control over the patient’s haemodynamic status. Better control seems to be essential in optimising circulating blood volume to optimise perfusion. In so doing we can minimise organ damage.
For the clinician to achieve this in fundamentally unstable patients, particularly those on ventilators at lung-protective settings is difficult. Arterial monitoring is unlikely to be reliable as it requires patients to be in sinus rhythm and can be affected by changes in vascular tone- i.e. when patients are vasodilated for pathophysiological or clinically-induced reasons i.e. sepsis or vasoactive agents. Furthermore it is time-consuming and labour intensive in an already stressed environment. So much so that haemodynamic monitoring per se has not been top of many practitioners’ to-do lists.
Follow the evidence: Monitor Haemodynamics… closely
But such are the clinical benefits of haemodynamic monitoring that it should be considered essential. Study after study says so, and it’s perhaps only because it has hitherto been considered a nuance of luxury proportion that it isn’t already. While it’s clear that this is not the time to be learning new techniques, oesophageal Doppler monitoring (TrueVue ODM+) is a simple and safe option. Deriving its data directly from the aorta guarantees the best stroke volume information and can guide fluid and other interventions quickly and in real time.
Keeping the patient in their haemodynamic “sweet spot” using Deltex’s ODM+ system is important for all the reasons mentioned here. Not to mention the evidential support from numerous other current publications and medical media. If our collective mission is to optimise outcomes and get to a good place with each patient as quickly as possible, we need to remember to monitor. And remember which is the most appropriate, most clinical evidence-supported system.