Relationship between polymorphonuclear leucocytes and the outcome of patients with severe trauma

Introduction

Major trauma is accompanied by a marked inflammatory reaction that involves infiltration of blood polymorphonuclear leucocytes (PMNs) into the injured area. This process is dynamic and evolves rapidly over the first 24–72 hours after injury. Activated PMNs can contribute to tissue damage by release of oxygen radicals, proteolytic enzymes and proinflammatory cytokines. The acute respiratory distress syndrome (ARDS) that occurs early after major trauma is characterized by a neutrophil infiltrate within the lungs. Also the inflammation, in response to brain injury, involves infiltration of neutrophils into the injured brain parenchyma.

Purpose

The aim of the study was to test the hypothesis that the outcome of severe traumatized patients would be influenced by the PMN count.

Methods

From December 2004 to November 2005, 40 multiple injured patients (28 male, 12 female, mean age 39 ± 18 years old) admitted to our ICU were retrospectively studied. The study protocol was approved by the local ethics committee. Ten of them had severe brain injury (GCS < 8) and 30 were admitted after major multiple trauma (ISS > 20). From the hematologic tests of the first 2 days post injury drawn from their records, the total peripheral leukocyte count, absolute neutrophil count and absolute lymphocyte count were recorded. The average values of the first 2 days for total leucocytes, absolute neutrophils and absolute lymphocytes were calculated for each patient. The overall outcome of the patients in the hospital was also recorded. The Student t test and the chi-square test were used for statistical analysis.

Results

Patients were divided into two groups according to their outcome. The absolute neutrophil count in survivors was significantly lower than those in nonsurvivors (P = 0.01). No significant difference was found in total leukocyte count and absolute lymphocyte count between the groups. The mortality rate was significantly higher in patients with absolute neutrophils >8000 than in those with absolute neutrophils <8000 (P = 0.03). See Table 1.

Table 1 (abstract P129)

Conclusion

A high absolute neutrophil count detected at the first and second day after severe injury is associated with an increased mortality. This finding must be verified in a prospective study with a large number of traumatized patients.