The Effect of Hypotension Predictive Index on Intraoperative Hypotension Events and Duration During Pancreatic Surgery. A Retrospective Pre-post Observational Study.

Intraoperative hypotension (IOH) is a relatively common event during surgery, occurring suddenly and often without any warning sign. Predicting IOH would help clinicians to set up a rapid response, reducing the number of hypotensive events and overall time of hypotension.

Historically the management of IOH has been reactive, despite the introduction of advanced arterial waveform analysis systems providing a number of cardiovascular parameters (arterial pressure, cardiac output, dynamic indices) which allow advanced intraoperative hemodynamic monitoring (FloTrac™, Edwards Lifesciences Corp., Irvine, USA). This changed when continuous blood pressure wave static and dynamic features extraction combined with Machine-Learning approach proved informative in identifying specific signatures associated with impending exhaustion of compensatory mechanisms. By fitting these features in a mathematical model it became available an easy-to-interpret Hypotension Predictive Index (Acumen™ HPI - Edwards Lifesciences, Irvine, CA), which can predict IOH up to 15 minutes prior to the clinical event. The HPI is expressed in a range from 0 to 100, the higher the number, the higher the probability and the shorter the time of occurrence of the hypotensive event. Therefore, combining arterial waveform analysis and HPI may provide timely prediction and goal-directed treatment plans based on the specific mechanism underlying IOH, such as relative hypovolemia, temporary vasoplegia or decreased inotropism.

Several studies have shown that IOH has a great impact on postoperative outcomes and tight control of blood pressure may be important especially in patients undergoing major surgery. These patients are often frail and bear greater risks of developing organ dysfunction, mainly renal insufficiency and myocardial injury. Futier et al. reported a 25% risk reduction of postoperative organ dysfunction when IOH is properly treated during surgery. Further, prospective studies showed that the use of HPI both decreased the total time of hypotension in non-cardiac surgery and reduced post-operative complications and hospital length-of-stay.

These studies addressed application of HPI in mixed cohorts of the population (orthopedic surgery, neurosurgery, general and vascular surgery, ENT surgery), but the duration and type of surgery are certainly two major factors affecting the occurrence and the severity of IOH. Among non-cardiac operations, major pancreatic surgery is generally complex and long-lasting. In our center roughly 180 patients undergo major pancreatic surgery every year and in our experience these patients are often debilitated and have reduced physiological reserve at the time of surgery. In addition, post-operative complications including bleeding, sepsis, bilio-digestive fistulas, acute kidney injury are common in this setting. For these reasons, the investigators believe that patients undergoing major pancreatic surgery represent an excellent model to evaluate the efficacy of HPI compared to the FloTrac™ alone as they can benefit from advanced hemodynamic monitoring and IOH prediction tools.

The aim of this study is to assess whether patients undergoing pancreatic surgery benefit from early prediction and goal-directed treatment of IOH using the HPI software compared to a goal-directed hemodynamic approach using the FloTrac™ monitoring system. The investigators plan to study the occurrence of IOH with and without the use of HPI in comparison with a FloTrac™ monitoring system. Furthermore, the study aims to evaluate if HPI software inclusion in an intraoperative hemodynamic management protocol leads to improved intraoperative cardiovascular stability and better clinical outcomes. Finally, the investigators want to explore whether the improved clinical experience using HPI predictive model correlates with the degree of IOH by analyzing data from patients managed only with this technology over time.