The strong ion gap and outcome after cardiac arrest in patients treated with therapeutic hypothermia: a retrospective study.
OBJECTIVE
This study investigates whether the strong ion gap (SIG) is associated with long-term outcome after cardiac arrest in patients treated with therapeutic hypothermia. The hypothesis of the study was that an elevated SIG was associated with unfavourable outcome after cardiac arrest.


METHODS
Retrospective review of records from 1995 to 2007 of patients who received cardiopulmonary resuscitation.


METHODS
Emergency department of a university hospital.


METHODS
Patients who were successfully resuscitated after cardiac arrest (n = 288) and treated with mild therapeutic hypothermia.


METHODS
None.


RESULTS
Acid-base variables were calculated according to Stewart's approach, as modified by Figge and Fencl, and were determined immediately on admission and 12 h after the return of spontaneous circulation. Acid-base variables were determined at 37 degrees C and are reported without correction for patient temperature. Differences in SIG were compared between patients with favourable (survival 6 months with cerebral performance category 1 or 2) and unfavourable outcomes. SIG on admission and 12 h after return of spontaneous circulation was higher in patients with unfavourable outcome (n = 151; 52%). SIG 12 h after return of spontaneous circulation was identified as an independent predictor of outcome. A SIG > 8.9 mmol/L was associated with an increased cumulative hazard of death.


CONCLUSIONS
An elevated SIG 12 h after return of spontaneous circulation may be associated with unfavourable outcome in patients after cardiac arrest treated with mild therapeutic hypothermia. The unmeasured anions hidden behind an elevated SIG may represent markers of tissue damage.
Department of Respiratory and Critical Care Medicine, Otto Wagner Spital, Vienna, Austria.
Georg-Christian
GC
Funk
Daniel
D
Doberer
Fritz
F
Sterz
Nina
N
Richling
Nikolaus
N
Kneidinger
Gregor
G
Lindner
Bruno
B
Schneeweiss
Philip
P
Eisenburger
D000136:Acid-Base Equilibrium / Q000502:physiology*; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006323:Heart Arrest / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D007362:Intensive Care Units; D017136:Ion Transport / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000628:therapy; D009460:Neurologic Examination; D012189:Retrospective Studies; D016896:Treatment Outcome