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An algorithmic approach to the very
high risk surgical patient
Why use an algorithmic approach? According to its definition, an
algorithm is a set of rules that precisely defines a sequence of
operations to perform a procedure or to solve a problem. In the
perioperative setting, such an algorithmic approach can be useful
firstly to analyze, and secondly, to reduce perioperative risks
during and after very complex surgical procedures. This comprises
of a) defining the procedure associated risks, b) defining the
patient associated risks, c) outlining strategies to optimize the
preoperative status, d) defining adequate hemodynamic monitoring,
and finally e) defining an adequate hemodynamic management
regimen.
When considering procedure associated risks, the Guidelines of
the Task Force for Preoperative Cardiac Risk Assessment and
Perioperative Cardiac Management in Non-cardiac Surgery from
the European Society of
”
Cardiology and the European
Society of Anaesthesiology
(ESC/ESA) represents
a very helpful tool
(1). In these guidelines
surgical procedures are
stratified to low (5% risk). However,
each individual surgical and anesthesiological experience also
needs to be taken in account with such stratifications.
The patient associated risk should also be stratified preoperatively
into an algorithmic approach. The ESC/ESA guidelines
also propose a practical procedure, based on the modified Lee
criteria (2): The individual risk is stratified according to the presence
of active cardiovascular/pulmonary diseases (unstable coronary
syndrome, acute heart insufficiency, significant arrhythmias,
symptomatic valvular disease, recent myocardial infarction),
the determination of the patients’ functional capacity (quantified
Professor Daniel Reuter
Department of Anesthesiology and Intensive Care Medicine,
University Clinic Hamburg-Eppendorf, Germany
Prof Reuter completed his Medical Education at the Julius Maximilians University in
Würzburg Germany, Columbia University New York USA and finally at the Ludwig-Maximilians-University
Munich Germany. He has specialized in both Anesthesiology and
Intensive Care Medicine in Tübingen Germany, and in Munich Germany. Prof Reuter
is currently Professor of Anesthesiology and Vice Chair of the Department of Anesthesiology
in the Center of Anesthesiology and Intensive Care Medicine Hamburg-Eppendorf
University Medical Center, Germany.
The underlying rationale should
always be to have the tools to optimize
blood flow in order to ensure
an adequate circulation, leading
to adequate end-organ perfusion,
resulting in less complications
and improved outcome.kk
”
by the determination of metabolic equivalents), and the presence
of clinical risk factors (known coronary artery disease, heart insufficiency,
insulin dependent diabetes mellitus, cerebrovascular
diseases, and renal insufficiency). This information can then be
transferred into a treatment-matrix which defines which further
diagnostic and therapeutic steps should be taken prior to surgery
(3).
Furthermore, this information can also serve as the basis for the
definition of an appropriate hemodynamic monitoring strategy:
The complexity and invasiveness of monitoring increases based
on the quantification of patient- associated, and surgery associated
risks, as described above. The underlying ratio should
always be to have the tools to optimize blood flow in order to
ensure an adequate circulation, leading to adequate end-organ
perfusion, resulting in less complications and improved outcome.
These tools are comprised of the assessment of
cardiac output, preload and fluid responsiveness
as well as the measurement of blood pressure.
More and more technologies are becoming
available to assess these parameters with less
and less, or indeed no invasiveness – however,
in highly complex pathophysiological states, such
as in severe hemodynamic instability, shock, or
systemic inflammation, those low or non-invasive
tools will potentially fail to provide the correct
measurements – so that in these circumstances, escalation to
monitoring techniques such as transpulmonary and pulmonary
artery thermodilution are justified.
However, and most importantly, hemodynamic monitoring can
only help to improve the outcome if it is embedded into a treatment
strategy. Here the algorithmic approach, which by its very
definition clearly determines the goals of hemodynamic optimization,
is essential. The basis of all these thus far proposed
treatment algorithms is very similar: Step one is preload optimization,
which is followed by an improvement in central blood
flow (cardiac output). Optimization of perfusion pressure (blood