A Pragmatic Multi-center Trial of Goal-directed Fluid Management Based on Pulse Pressure Variation Monitoring During High-risk Surgery

This open label, multicenter, before-and-after trial study was carried out in three hospitals, Hospital das Clínicas of São Paulo University Medical School, Hospital São Paulo of São Paulo Federal University and Hospital Padre Albino.

Subsequently obtaining IRB approval (Ethical Committee N° 0616/06 HCFMUSP) and written informed consent, high-risk patients undergoing open major surgery under general anesthesia and who required ICU admission postoperatively were enrolled from June 2007 to April 2008 (control period), followed by a phase-out period (April 2008 to July 2008) and an intervention period (July 2008 to June 2010).

High-risk surgical patients were defined as those 60 years of age or older referred to postoperative ICU care due to the presence of at least one clinical comorbidity such as coronary artery disease, chronic obstructive pulmonary disease, cerebrovascular disease, poor nutritional status, a predicted intraoperative period greater than 6 hours or predicted acute massive blood loss. All of these criteria have been used in previous studies, and they were adopted for this study. Patients with severe aortic regurgitation, cardiac arrhythmias, congestive heart failure, patients undergoing renal replacement therapy, those undergoing palliative surgery were excluded from the study.

Patients were enrolled into a standard fluid resuscitation period (Control group) or a goal-directed fluid-management group based on pulse pressure variation during the intervention period (Intervention group). Following the control period, the three-month phase-out period included education and preparation of all anesthesiology staff and logistic arrangements for the evaluation of fluid responsiveness using automated PPV measurements. Finally, the intervention period was replicated in the same season of the year as the control period.

Anesthesia care and fluid management Intraoperative monitoring standards for high-risk patients in all institutions included electrocardiography, invasive arterial blood pressure catheters, pulse oximetry, temperature monitoring, and measurement of inspiratory and expiratory gas concentrations. Additional intraoperative monitoring such as central venous catheterization was indicated on an individual basis by the attending anesthesiologist. In the interventional phase, however, intraoperative fluid adjustment was strictly directed by online PPV assessment.