Near infrared spectroscopy during and after cardiac arrest--preliminary results

Abstract

Objective: To evaluate if regional cerebrovascular oxygen saturation (rSO2) is linked to systemic oxygenation and if impaired regional cerebral oxygenation affects outcome in cardiac arrest patients.

Design: Prospective, observational study.

Setting: Emergency department of a University Hospital.

Subjects: Patients during cardiac arrest or after restoration of spontaneous circulation.

Interventions: To measure rSO2 an infrared light-emitting probe was applied to the patient's forehead after arrival in the emergency department. Data were collected continuously together with blood pressure and pulse oximetry. Each variable measured immediately after arrival was used for calculation.

Endpoints: Best outcome (cerebral performance category) or death within one week.

Measurements and main results: Regional SO2 was measured in 18 consecutive patients. Six patients presented with cardiac arrest on arrival and rSO2 was measured during chest compression. Twelve patients had achieved restoration of spontaneous circulation before they arrived in the emergency department. No association was found between rSO2 and pulse oximetry or rSO2 and blood pressure. All patients surviving for one week (n = 9) achieved a significantly higher median rSO2 on arrival than nonsurvivors (n = 9) (63% and 46%, respectively; p = 0.003). Median rSO2 was lower in the group arriving without spontaneous circulation (n = 6) than in patients after restoration of spontaneous circulation (n = 12) (44% and 63%, respectively; p = 0.009). This difference was not found in pulse oximetry readings. Patients with restoration of spontaneous circulation surviving the first week after cardiac arrest (n = 8) had a higher rSO2 than patients with restoration of spontaneous circulation who did not survive (n = 4) (65% and 48%, respectively). Time from restoration of spontaneous circulation to arrival was not different between the two groups.

Conclusion: By showing that low rSO2 readings after cardiac arrest are associated with a higher mortality, this new, non-invasive and easily applicable technique might help to prognosticate outcome and offers new insights into monitoring cerebral oxygenation after cardiac arrest.