Perioperative interventions and postoperative outcomes

Abstract

Background: Postoperative complications are frequent causes of postoperative mortality. Such complications may also lead to a prolonged period with decreased functional and cognitive status. Perioperative care is a factor in postoperative morbidity and mortality. Until now no common international definitions and classifications of postoperative complications have been established. The group of surgical patients with the highest risk of postoperative complications accounts for perhaps 80% of intra-hospital deaths. With the high volume of surgery performed worldwide, even a slight reduction in complications would result in a lower number of preventable deaths. There are several theories on how to decrease postoperative complications and improve patient safety and patient care. Two factors, checklists and perioperative fluid balance, are investigated in this thesis. The overall aim of this thesis is twofold: 1. To study perioperative complications and outcome after major surgery - Paper I aimed at creating standard definitions of outcome measures for use in pragmatic large perioperative clinical trials. - Paper II aimed at providing data on perioperative mortality after non-cardiac surgery across Europe. 2. To contribute in finding ways to reduce complications after major surgery - Paper III aimed at identifying the prevalence of surgical checklist use and possible relationship with mortality. - Paper IV aimed at evaluating the effect of perioperative goal directed fluid therapy guided by ScvO2 in open colorectal surgery. Result: Paper I was a literature review to assess the current state of knowledge about surgical outcome definitions. A standardized list was created for use in perioperative research and clinical audition. The outcome measures described are organized into four different categories: Individual adverse events, Composite outcomes, Grading of complications and Health related quality of life. Paper II was a 7 day cohort study (European Surgical Outcome Study) conducted in 498 hospitals across 28 European countries. Intra-hospital mortality data was registered for all adult patients undergoing non-cardiac surgery. The overall intrahospital mortality throughout Europe was 4%. A variation in mortality after surgery throughout Europe could be confirmed. This may indicate a discrepancy in standard of care. Identification and standardisation of key factors in perioperative care would subsequently improve outcome throughout Europe. Paper III determined the point prevalence of checklist use in Europe and its association with in-hospital mortality, using data collected from the European Surgical Outcome Study. There was a marked variation between checklist use and mortality in Europe. The use of a surgical checklist was associated with lower mortality. Although there is no causality demonstrated, checklist use may be an indicator of hospitals focusing on improved perioperative care and therefore decrease mortality. Paper IV investigated the use of goal directed fluid therapy in 241 patients undergoing abdominal surgery and its influence on postoperative morbidity. Patients were randomized in a control group receiving standard fluid therapy and an intervention group using central venous oxygen saturation as a surrogate for cardiac output to guide fluid therapy. Although there was a difference in the amount of fluid given between the two groups, the complication rate 30 days after surgery was equal. Conclusion: We proposed standardised outcome measures for use in future trials investigating postoperative complications. This contributes to a meaningful comparison of quality of care in future clinical trials and leaves less room for interpretation of outcome measures. It is not likely that one single intervention in the perioperative period will markedly affect outcome. Most likely a multifactorial intervention will be successful in reaching this goal. However, specific research in the high-risk surgical population is lacking. It can be assumed that this patient group would have the greatest benefit from an improved perioperative care pathway. Better data may be available after foundation of national and international perioperative registers. This may help to establish a greater research community in perioperative outcome research and assist to identify factors in the perioperative care pathway that improve outcome.