Protein S100 as a marker for cerebral outcome after cardiopulmonary resuscitation

Introduction

S100 is a CNS-specific protein, derived from the cytosol of glial cells, that can be detected in peripheral blood after structural brain damage. We prospectively examined the prognostic value of S100-levels after cardiopulmonary resuscitaton (CPR).

Patients and methods

In 17 consecutive patients admitted to a medical intensive care unit (ICU) after primary successfull cardiopulmonary resuscitation blood specimens were collected during the 7 days following CPR in a certain scheme, starting 1 h after the onset of CPR. On admission pH, base excess, serum lactate, time from cardiac arrest until onset of CPR, duration of CPR and dose of catecholamines used were recorded. Blood samples were centrifugated and sera stored at -20°C. Levels of protein S100 were measured using a commercial immunoluminometric assay (Sangtec 100^® Byk Sangtec Diagnostica, Dietzenbach, Germany) according to the guidelines of the manufacturer. Reference level was < 0.34 µg/l. Cerebral recovery was evaluated by the five-point cerebral performance category (CPC) on ICU demisson [1].

Results

Mean age was 66 yrs, median 67, range 35-78 years, 9/17 (65%) were male, 14/17 (82%) survived and were evaluated by the CPC. 5/13 (38%) met Category 1 criteria (conscious and alert/normal function), 2 met CPC 2 (conscious and alert/moderate disability, 2 met CPC 3 (conscious with severe disability), 4 met CPC 4 (comatose), 1 met CPC 5 (brain death). In 16/17 patients an elevated S100) was measured with a mean value of 5.13 µg/l, range 0.5-15.4, median 3.8 µg/l, with a maximum 1 h after CPR in 13/16 patients. In all patients of category 1 normal or slightly elevated levels (0.1-0.7 µg/l) were found, returning to normal within a few hours. In category C the highest S100 values (8.8/12.1 µg/l) of surviving patients were found, in contrast to category D with moderate elevated levels (1.7-5.4 µg/l). Patients who died had S100 values of 4.7-15.4 µg/l. No correlation was seen between pH, base excess, serum lactate on admission, catecholamine dosis needed during CPR and neurological outcome.

Conclusion

S100 seems to be a sensitive marker of cerebral injury due to diffuse hypoxia after CPR. Normal S100 values excluded severe cerebral damage. Normal or slightly elevated levels of S100 (= 0.7 µg/l) are correlated with good neurological outcome, but high S100 values do not necessarily predict an unfavourable prognosis.