Analysis of Modified Early Warning System scores and intraoperative factors on the incidence of sepsis and septic shock after elective major surgery

Introduction

Severe sepsis is an important cause of morbidity and mortality following major surgery. Factors that are associated with an increased risk of sepsis following surgery include emergency surgery, patient co-morbidities, allogeneic blood transfusion and degree of surgical insult [1]. Physiological track-and-trigger systems are widely used to identify deteriorating patients. The Modified Early Warning System (MEWS) is one such system, but has not been studied in regard to predicting the development of sepsis after surgery. Although high MEWS scores are associated with increased hospital mortality, the sensitivity of MEWS and other physiological track and trigger scores for predicting death or admission to intensive care is low [2].

Methods

We carried out a prospective cohort study on 101 patients undergoing elective major surgery in a large university teaching hospital. The patients were followed up for 10 days, and the incidence of sepsis and septic shock was documented. MEWS scores were recorded daily for each patient. Admissions to critical care were documented, along with critical care length of stay.

Results

Twenty-seven (27%) patients developed sepsis and nine (9%) developed septic shock. Factors associated with the development of sepsis were intraoperative blood transfusion (P = 0.013), duration of operation (P = 0.004) and a postoperative MEWS score greater than 3 (P = 0.0003). Using multivariate logistic regression analysis, a MEWS score greater than 3 after surgery was the only factor that remained significantly associated with sepsis (odds ratio 4.89, P = 0.003). Although a high MEWS score was associated with sepsis after surgery, only five (19%) patients who developed sepsis had an abnormal MEWS score prior to (mean 4.6 days) sepsis being diagnosed.

Conclusions

The routine use of MEWS scores in postoperative elective surgical patients may help to identify those patients at risk of developing sepsis.