Monday 4 June, 0830-1000H, Hall A3
PLEASE NOTE: the speakers in this session are asked to adopt a position to convince the audience about their particular situation. This position does not necessarily represent the speakers’ personal views.
This innovative session on the last day of Euroanaesthesia has 6 short communications (10 min each), and is based on a practical approach at the bedside regarding the decision to give fluids or not in perioperative medicine.
The patient is hypotensive: Professor Daniel Chappell, LMU University Hospital of Munich, Germany
Hypotension is a very frequent phenomenon in the perioperative setting. A recent meta-analysis showed intraoperative hypotension to significantly increase the risk of postoperative 30-day mortality, major adverse cardiac events, especially myocardial injury, and acute kidney injury in adult patients after non-cardiac surgery.
Dr Chappell says: “Despite the ideal blood pressure remaining unknown, it seems that the mean arterial pressure should be maintained above 60-70 mm Hg (70-80 mm Hg in hypertensive patients). The longer and more pronounced the hypotensive phase is, the more adverse events occur so that an effective and immediate intervention is required. The underlying causes for hypotension are as complex as the respective therapeutic approaches. Fluid therapy is an important strategy when the patient is hypovolaemic. This can be caused by dehydration or acute blood loss during surgery or trauma. In other cases other options might be more suitable.”
The patient develops oliguria: Dr Matthieu Legrand, St-Louis Hospital & University Paris Diderot, France
Oliguria is one of the most frequently condition triggering fluid loading in critically ill patients or in the perioperative setting. While Oliguria can be a marker of hypovolaemia or dehydration, it can also be associated but congestive heart failure, intra-abdominal hypertension or intrinsic acute kidney injury with no participation of low intravascular volume or hypoperfusion.
Even though sustained oliguria (i.e.>6 hours) should trigger a haemodynamic and etiologic investigation, oliguria should not be considered as a reliable biomarker of hypovolaemia and therefore be systematically a trigger for fluid loading. In this area, the clinical setting and the clinical judgment are key to appreciate the nature of oliguria and propose the best response.
Dr Legrand says: “While fluid loading should be performed in oliguric patients with symptoms of dehydration, in contexts of hypovolaemic shock (i.e. burns, trauma, surgery etc), more advanced investigation should aim at determining the potential participation of low intravascular volume in oliguric patients not responding to first line fluid loading or with history or clinical symptoms of heart failure.”
The central venous pressure is low: Dr Jihad Mallat, Centre Hospitalier du Dr. Schaffner de Lens, Lens, France.
Central venous pressure (CVP) or right atrial pressure determines the preload of the right ventricle and the cardiac output (CO) of the heart as a whole. CVP is determined by the interaction of cardiac function and return function, and a change in either can alter the CVP.
“These simple relationships can be used to ascertain the nature of a change in haemodynamic status and the choice of appropriate treatment,” says Dr Mallat. “Thus, CVP can be very useful for determining the cause of a drop in CO. In case of low blood pressure and a decreased CO, if the CVP is low this means that the primary concern is a reduction in the venous return and giving fluid will probably resolve the problem. In this regard, it was found that almost two-thirds of the patients with a CVP less than 8 mm Hg responded to fluids. Furthermore, it is probably less dangerous to administer fluids in a non-responsive patient with a low CVP since the risk of organ oedema formation is low.”
Because indicators of preload-dependency are high: Professor Daniel A. Reuter, Rostock University Medical Center. Rostock, Germany
Giving fluids in perioperative care has primarily one indication: to increase stroke volume and cardiac output by using the Frank-Starling mechanism. This mechanism describes the dependency of stroke volume from ventricular preload.
“If an increase of preload (i.e. administration of fluids) does not lead to an increase of stroke volume, the ventricle is working in its current condition preload-independently. Giving fluids would be even harmful,” explains Professor Reuter. “Indicators of preload-dependency, so called dynamic parameters of fluid responsiveness (SVV, PPV, passive leg raising, and others) give particular this information: Is the ventricle currently preload-dependent or not. Giving fluids in order to increase stroke volume with valid indicators of preload-dependency showing that the ventricle is currently preload-independent does not make sense. Indicators of preload-dependency should always justify haemodynamics-associated fluid administration.”
The two other presentations will be the patient has tachycardia, presented by Professor Azriel Perel, Sheba Medical Center, Tel Aviv University, Israel; and the cardiac output is low by Professor Thomas Scheeren, Univeristy Medical Center Groningen, Netherlands.