Cerebral tissue saturation, the next step in cardiopulmonary resuscitation management?

Abstract

The goal of cardiopulmonary resuscitation (CPR) is to preserve the pre-arrest neurological state by maintaining sufficient cerebral blood flow and oxygenation, but the predictors thereof remain largely unknown. Despite recent attempts to improve the quality of basic and advanced life support, no monitored link to the neurological and physiological response of these CPR efforts has been established. The difficult decision to end pre-hospital resuscitation efforts is currently based on the circumstances of cardiac arrest, length of resuscitation efforts (if available), knowledge of pre-morbid physiological reserves, and (if present) end-tidal carbon dioxide (ETCO2) measurement. ETCO2 is currently the only parameter proven to correlate with the likelihood of return of spontaneous circulation (ROSC), although the prediction of long-term outcome based on ETCO2 values has not been established [1],[2]. To measure ETCO2 adequately, invasive airway management is necessary and measured values are influenced by different lung pathologies.

By using two sensors on the forehead, near infrared spectroscopy (NIRS) measures the regional difference between oxygenated and deoxygenated hemoglobin, which expresses the difference in oxygen supply and demand. It determines cerebral tissue saturation non-invasively and independent of pulsatile flow. Müllner and colleagues [3] were the first to examine the use of cerebral oxygenation in (post-)cardiac arrest circumstances. They recorded cerebral saturation in six patients with ongoing CPR in the emergency department. Patients who achieved ROSC had higher cerebral saturation values compared with the single patient without ROSC. Cerebral NIRS was also studied during coronary artery bypass surgery. A correlation between desaturation and cognitive dysfunction [4], prolonged length of hospital stay [5], and perioperative cerebrovascular accident [6] was observed, and accordingly two landmark studies [7],[8] showed that a goal-directed protocol preventing cerebral desaturation resulted in a decrease in length of intensive care unit and hospital stay, lower incidence of major organ morbidity and mortality, and decreased risk of cognitive decline [4]-[8].