Intraoperative Monitoring and Optimisation of Tissue Oxygenation In High-Risk Surgical Patients for reduction of postoperative complications

Tissue hypoxia is supposed to occur frequently during high-risk surgery or in
high-risk patients undergoing surgery. However, it is difficult to detect since
conventional monitoring devices look either at the input site of the tissues
(arterial blood) or at the downstream side of the tissues (venous blood,
lactate). Recently, monitoring devices looking into the tissues have been
introduced and shown its ability to differentiate between survivors and
nonsurvivors (1). Nevertheless, due to a lack of available methods there is a
very limited use of monitoring tissue oxygenation intraoperatively (i.e. in the
OR) as of yet.
Undetected intraoperative tissue hypoxia may contribute to postoperative organ
dysfunction, prolonged ICU or hospital stay, and increased mortality.
Furthermore, there is a lack of protocols for the perioperative management of
high-risk surgical (HRS) patients. Recently, there is evidence that the use of
a goal directed therapy might improve survival (2) and reduce the incidence of
postoperative complications (3-5).
The purpose of this clinical study is to obtain human clinical data in order to
demonstrate that a decrease in the incidence of post-operative complications
can be achieved by following an optimizing protocol, based on targeting tissue
oxygenation (StO2).
Tissue oxygenation (StO2) will be monitored by near infrared spectroscopy, a
non-invasive technique. It has been shown to be of value in predicting organ
dysfunction in trauma patients (6) as well as outcome in patients with sepsis
(1, 7). Also in the perioperative setting it has been demonstrated recently
that low StO2 is associated with worse outcome (8).
We hypothesize that monitoring and treating tissue hypoxia (defined as a
StO2<80%) with the use of a protocol will reduce postoperative complications in
high-risk surgical patients.

Tissue hypoxia occurs frequently during high-risk surgery in high-risk
patients. We want to see if an algorithm aimed at optimizing intraoperative
tissue oxygenation reduces perioperative complications as well as length of
stay in the intensive care unit (ICU LOS), 28-day mortality, and the duration
of mechanical ventilation in these patients

randomized pilot study

If despite volume expansion the StO2 will be below 80%, norepinephrine (initial
dose 0.03 ug/kg/min) and/or dobutamine infusion (initial dose of 2.5 ug/kg/min)
will be started and gradually increased until the goal is reached. In addition,
packed red blood cells will be given if needed. These interventions all belong
to standard care, only its timing will be guided by the StO2 readings according
to a fixed protocol.

Since the intervention is limited to the intraoperative phase, there will be no
additional burden for the patient. The follow-up data recordings will be taken
from standard patient files or hospital information system; there is no contact
with the patient necessary. In the intervention group, there is no additional
risk as compared to the control group receiving standard therapy, unless start
of fluid or vasoactive therapy is now initiated and guided by the monitoring of
StO2.