key: cord-0807864-zdbnoy1q
authors: Bendjelid, Karim; Muller, Laurent
title: Hemodynamic monitoring of Covid-19 patients. Classical methods and new paradigms
date: 2020-09-04
journal: Anaesth Crit Care Pain Med
DOI: 10.1016/j.accpm.2020.09.001
sha: 52e07bafcc65d81676bfe1f826aaac06ddc0fab6
doc_id: 807864
cord_uid: zdbnoy1q

nan

In the current issue of Anaesth Crit Care Pain Med, Michard et al. 1 reported an international survey examining hemodynamic monitoring and management in COVID- 19 Intensive Care patients 1 . The survey database was closed on May 16 th after receiving 1000 valid questionnaires for analysis. Responses had come mainly from Europe (n = 460) and America (n = 434). Most responders were intensivists-anaesthetists (n = 920) but 80 were trainees. 23.7 % of physicians had had over 10 years' experience working in the ICU.

Interestingly, when analysing the data, the authors found that the majority of COVID-19 ICU patients required vasopressor support, with certain changes in cardiac function patterns warranting echocardiographic monitoring. Moreover, most responders had followed the current recommendations on the use of echocardiography and the need to predict fluid responsiveness (FR) 2 . Regarding non-advanced hemodynamic monitoring, the survey reports that central venous catheters (CVCs) and invasive arterial monitoring were used by almost all respondents. CVCs were reported to be used for drug administration, measuring venous oxygen saturation, central venous pressure and determining the veno-arterial PCO2 gradient 3 .

On certain points, these results are both homogeneous and rational 4 . The fact that echocardiography was commonly used for COVID-19 patients is comprehensible as the present non-invasive technique gives a complete cardiovascular evaluation 4 . However, the almost comparable percentage of incidences for both left ventricular (LV) systolic dysfunctions and hypovolemia during echocardiography may question the valid mechanism of LV systolic dysfunctions. Similarly, focusing on applied physiology, another finding should be discussed in depth. Indeed, the fact that the majority of patients required vasopressor support is puzzling, even though we can agree that only a few patients could present both cardiogenic and distributive shocks 5, 6 . Indeed, the key information to know regarding vasopressor requirements in COVID-19 ICU patients is the mean dose used. For instance, in the majority of cases, deep sedation 7 , neuromuscular blocking agents and positive pressure ventilation induce relative hypovolemia and hypotension 8 which impose modest doses of norepinephrine 9 .

Compared to previous large international surveys published in 2015 4,10 , the current report shows that cardiac output monitoring and FR indexes have been largely used for the J o u r n a l P r e -p r o o f hemodynamic assessment of critically ill patients admitted for COVID-19. In 2015, hemodynamic status was assessed according to clinical criteria alone in more than two thirds of cases, despite the fact that numerous studies showed that arterial pressure, heart rate, skin mottling or any other clinical parameter led to poor evaluation of FR in 50% of cases 4, 10 . In those two reports, cardiac output monitoring, pulse pressure variation and central venous pressure were used in fewer than 20 % of cases whereas echocardiography was used in fewer than 10% of cases before deciding on fluid infusion. At the same time, the European Society In the present report 1 , systolic ventricular dysfunction was rare (around 20% of cases), which is consistent with another recent report 11 . Nevertheless, cardiac dysfunction cannot be restricted merely to severe systolic dysfunction. Indeed, occult diastolic dysfunction (not studied in the present report) appears common 11 and may have a significant impact, especially in the ventilator weaning period. Finally, in this report, the echocardiographic assessment of FR and/or definition of hypovolemia are not precisely detailed. The only way to be sure that the patient is hypovolemic is to demonstrate a 10 to 15% increase in CO/SV/subaortic VTI after conventional fluid challenge, passive leg-raising test or minifluid challenge 2 . "Simple" tools like respiratory-induced variations in diameter of the inferior vena cava are very popular, but have limited accuracy in predicting FR due to numerous false positive or false negative cases, both in ventilated and non-ventilated ICU patients [12] [13] [14] [15] . Therefore, defining hypovolemia or FR with echocardiography is of paramount importance and the choice of index could considerably influence the number of responders/non responders.

Lastly, considering COVID-19 patients from a pathophysiological viewpoint, various studies have demonstrated the complex interplay between the renin-angiotensin-aldosteronesystem (RAAS) and SARS-CoV-2. In this respect, SARS-CoV-2 uses the host protein angiotensinconverting enzyme-2 (ACE2) as a co-receptor to gain intracellular entry into the lung 16 . Now, it is a known fact that the primary role of ACE2 is to efficiently degrade Angiotensin II (ANGII) 17 .

Consequently, the loss of ACE2 shifts the system to an overall higher ANGII level due to ACE2's impaired ability to degrade it 18 . ANG II is a well-known potent vasopressor agent which could be used in conjunction with other vasopressors to stabilize critically ill patients during refractory septic shock and reduce catecholamine requirements 19 . Interestingly, Liu et al. recently reported that the circulating levels of ANGII were significantly higher in patients with COVID-19 than in healthy controls 20 . The present fact may explain the relatively spectacular haemodynamic stability of patients with COVID-19, even in deeply sedated mechanically ventilated patients, with a tendency towards a hypertensive profile during the weaning stage 18 .

Over the last two decades of the 2 1st century, it has not been clear which method of hemodynamic monitoring to use with critically ill patients. However, our understanding of these subjects is constantly evolving, and several certainties have emerged regarding the J o u r n a l P r e -p r o o f central role of CO monitoring, echocardiography and FR assessment. Nowadays, evidencebased medicine (EBM) is especially necessary to demonstrate the efficacy of new techniques as the financial side of health delivery is under increasing scrutiny. However, the reductionist tradition of EBM is probably inappropriate when applied to a complex clinical disease like COVID-19, where several organs and new pathological concepts are involved (multimorbidity).

In the present context, a clinical survey at least has the merit of reflecting a broad image of experienced physicians' clinical practices.

Haemodynamic monitoring and management in COVID-19 intensive care patients: an International survey

Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine

ScvO(2) as a marker to define fluid responsiveness

Fluid challenges in intensive care: the FENICE study: A global inception cohort study

Evaluation and management of shock in patients with COVID-19

Association of Cardiac Injury With Mortality in Hospitalized Patients With COVID-19 in Wuhan, China

Sepsis Campaign Guidelines Committee including The Pediatric S: Surviving Sepsis

Campaign: international guidelines for management of severe sepsis and septic shock

Right atrial pressure: determinant or result of change in venous return?

Preparedness and Reorganization of Care for Coronavirus Disease 2019 Patients in a Swiss ICU: Characteristics and Outcomes of 129 Patients

Volume expansion in the first 4 days of shock: a prospective multicentre study in 19 French intensive care units

Spectrum of Cardiac Manifestations in COVID-19: A Systematic Echocardiographic Study

Influence of Diaphragmatic Motion on Inferior Vena Cava Diameter Respiratory Variations in Healthy Volunteers

AzuRea g: Respiratory variations of inferior vena cava diameter to predict fluid responsiveness in spontaneously breathing patients with acute circulatory failure: need for a cautious use

Accuracy of Ultrasonographic Measurements of Inferior Vena Cava to Determine Fluid Responsiveness: A Systematic Review and Meta-Analysis

Paediatric Research in Emergency Departments International C: Does Respiratory Variation in Inferior Vena Cava Diameter Predict Fluid Responsiveness: A Systematic Review and Meta-Analysis

COVID-19, ACE2, and the cardiovascular consequences

Circulating activities of angiotensin-converting enzyme, its homolog, angiotensin-converting enzyme 2, and neprilysin in a family study

Should we use angiotensin II infusion in COVID-19-associated vasoplegic shock?

Angiotensin II in Refractory Septic Shock

Clinical and biochemical indexes from 2019-nCoV infected patients linked to viral loads and lung injury