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Crit Care. 2010; 14(Suppl 1): P148.
Published online 2010 March 1. doi:  10.1186/cc8380
PMCID: PMC2934197

Tissue microdialysis in critically ill septic patients: associations with sepsis severity and mortality

Introduction

In vivo microdialysis (MD) is a bedside sampling method that permits continuous analysis of a patient's extracellular tissue chemistry without consuming blood. MD is performed by implanting a commercially available catheter that mimics a blood capillary at the site of interest.

Methods

A total of 35 (20 men) mechanically ventilated septic patients having a median age of 60 years were studied. All patients met the ACCP/SCCM consensus criteria for sepsis. Upon sepsis onset, a microdialysis catheter (CMA 60; CMA, Solna, Sweden) was inserted into the subcutaneous adipose tissue of the upper thigh. The dialysate samples were collected in microvials and were analyzed immediately for glucose, pyruvate, lactate, and glycerol using a mobile CMA ISCUS analyzer. The lactate/pyruvate (L/P) ratio was automatically calculated. Measurements were performed six times per day during the first 6 days from sepsis onset. The daily mean values of MD measurements were calculated for each patient.

Results

Sepsis severity of the study group was graded as follows: sepsis (n = 5), severe sepsis (n = 2) and septic shock (n = 28). APACHE and SOFA scores at study entry were 23 ± 4 and 8 ± 3, respectively. Overall, 18 patients died yielding an ICU mortality rate of 51%. MD revealed that at study entry patients with septic shock had higher lactate (3.5 ± 1.6 vs 1.8 ± 0.9, P = 0.01), and higher pyruvate (204 ± 137 vs 95 ± 68, P = 0.04) levels compared with septic patients without shock. In contrast, the two groups had similar values for glucose (5.9 ± 2.7 vs 4.3 ± 2.9, P = 0.18), glycerol (369 ± 225 vs 252 ± 171, P = 0.21), and L/P ratio (83 ± 289 vs 75 ± 150, P = 0.92). Septic shock correlated with SOFA on day 1 (r = 0.55, P = 0.001), APACHE II (r = 0.42, P = 0.01), lactate on day 1 (r = 0.48, P = 0.004), lactate on day 2 (r = 0.50, P = 0.002), pyruvate on day 1 (r = 0.040, P = 0.018), and with pyruvate on day 2 (r = 0.35, P = 0.04). Nonsurvivors had higher glycerol (426 ± 236 vs 253 ± 157, P = 0.01) at study entry and on day 1 (437 ± 260 vs 282 ± 169, P = 0.04) compared with survivors. Nonsurvivors also had higher pyruvate levels on day 1 (170 ± 99 vs 104 ± 65, P = 0.03) and on day 2 (150 ± 81 vs 97 ± 61, P = 0.04). Logistic regression analysis showed that APACHE II (OR = 1.312, P = 0.06) and glycerol on day 1 (OR = 1.005, P = 0.04) independently predicted patient outcome.

Conclusions

MD seems to be a safe and promising tool in grading sepsis severity and in predicting early mortality in critically ill patients.


Articles from Critical Care are provided here courtesy of BioMed Central