Impaired blood PMN migration as an indicator of increased susceptibility for bacterial infections in critically ill patients

Objective

Directed migration is a crucial element of PMN's defence capacity against microorganisms in a septic state.

The aim of our study was to look at the course and the significance of PMN migration capacity in surviving and nonsurviving critically ill patients.

Method

Intensive care patients with the diagnosis of SIRS or sepsis according to the SCCM/ACCP criteria were enrolled in this prospective study. The APACHE III score for each patient was calculated within 24 hours of admission.

PMN migration capacity was measured in 30 μl fresh whole blood in a membrane filter assay. Measurements were made daily from admission until discharge from the ICU or until death.

Numbers and distribution of the PMNs immigrant into the filters were evaluated in an automated image analyser. The relevant parameter was the percentage of PMNs migrating from the blood samples into the filters upon FMLP stimulation.

In parallel, the PMN blood count, reactive oxygen species production, blood levels of C-reactive protein, PMN elastase, procalci-tonin, neopterin and sL-selectin were determined.

Results

Sixteen patients (10 men/six women), mean age 48.8 ± 16.43 and mean APACHE III score 94.37 ± 23.71, were investigated. During the major part of the observation time, all patients had migration values below the critical minimum of 6%. The nonsurvivers kept this low reactivity until death, while survivors regained normal PMN migration during the period of clinical recovery. No such discriminative power could be attributed to the other inflammation parameters.

Conclusion

PMN migration was impaired both in sepsis and SIRS. An improvement of PMN migration capacity signals the restoration of PMN-based immunity and may be a useful aid in deciding how long to maintain and when to discontinue antimicrobial therapies in intensive care patients.