Prevalence of endotoxemia in a population of patients admitted to an intensive care unit after elective surgery

Introduction The aim of this study was to investigate the prevalence of endotoxemia early after elective surgical procedures in patients admitted to an ICU of a university hospital. Methods One hundred and four nonselect patients were recruited. Patients were excluded if they were admitted during the weekend or from another ICU and if they were on chronic dialysis. Within 4 hours of admission functional data were collected and severity scores (APACHE, SOFA) calculated. Arterial blood samples were also taken and processed according to Spectral Diagnostics' endotoxin activity (EA) assay [1]. The method allows one to express EA as a function of each patient's neutrophil chemiluminescence activity (on a scale from 0 to 1). An EA level of 0.4 is approximately equivalent to an endotoxin concentration of 25–50 pg/ml, and a level of 0.6 is approximately equivalent to a LPS concentration of 100–200 pg/ml. Data were analysed according to EA ranges: low (EA < 0.4), intermediate (0.4 ≤ EA < 0.6), and high (EA ≥ 0.6). Differences between ranges of EA were assessed by analysis of variance (Sigma Stat, SPSS), accepting P < 0.05 as significant. Data are expressed as the mean ± SD. Results In our case mix, patients were 68 (65%) in the low group, 17 (17%) in the intermediate group and 19 (18%) in the high group. Age (61 ± 17 years) was not significantly different in the three groups (P = 0.493). Functional and severity scores were not significantly different between groups. Average values were as follows: WBC 11,093 ± 4605 n/mm3 (P = 0.385), HR 76 ± 16 bpm (P = 0.898), MAP 88.8 ± 13.6 mmHg (P = 0.576), lactate 1.18 ± 0.77 mmol/l (P = 0.370), PaO2/FiO2 383 ± 109 mmHg (P = 0.474), APACHE II score 8.3 ± 3.7 (P = 0.542) and SOFA score 1.5 ± 1.4 (P = 0.245). Interestingly, those patients with higher levels of EA were characterized by longer length of stay in the ICU. The ICU length of stay was 1.9 ± 3.1 days in the low group, 8.7 ± 6.7 days in the intermediate group and 4.7 ± 7.7 days in the high group (P = 0.038). Conclusion A rather high number of patients admitted to the ICU following elective surgery are characterized by intermediate-high levels of endotoxemia, as assessed by the EA assay, despite their relative low level of complexity on admission. High levels of EA were associated with a longer length of stay.