Introduction:
Reliable non-invasive monitoring of cerebral blood flow (CBF) during cardiac arrest would greatly facilitate goal-directed brain resuscitation during CPR. The Ornim c-FLOW™ provides real-time, continuous, non-invasive, direct monitoring of CBF via ultrasound tagged near infrared spectroscopy using adhesive sensors applied to the forehead. Values range from 0-100 units with a reported baseline value of 55±7 units (mean±sd). C-FLOW™ values are refreshed every three seconds for each of two forehead probes. The feasibility of using c-FLOW™ to monitor CBF during cardiac arrest has not been previously reported.
Methods:
The c-FLOW™ was applied in the ED to adult patients undergoing CPR for cardiac arrest that occurred in the ED or outside the hospital. c-FLOW™ values were continuously recorded during CPR and for up to 6 hours post-ROSC. c-FLOW™ values were correlated with corresponding end-tidal CO
2
(PetCO
2
) values during CPR. Changes in c-FLOW™ values after vasopressor therapy were also quantified.
Results:
c-FLOW™ values were continuously recorded on patients undergoing CPR during 10 cardiac arrests. Initial, minimum, maximum, and mean values during CPR were 30.7±12.7, 17.3±15.0, 51.3±15.6, and 31.3±12.6 units, respectively. Maximum values after ROSC and VA ECMO were 43.0±10.9 and 59.0±12.0 units, respectively, and mean values after ROSC and VA ECMO were 24.0±11.7 and 35.3±12.7 units, respectively. The minimum value recorded after cessation of resuscitation efforts was 1.7±3.7 units. There was no significant correlation between c-FLOW™ values and simultaneous PetCO
2
values during CPR (R
2
0.01, p>0.05). c-FLOW™ values increased 7.6±8.5 units after IV/IO epinephrine boluses during CPR, though increased less with each subsequent bolus.
Conclusions:
Application of the c-FLOW™, a continuous real-time monitor of CBF, during cardiac arrest is feasible in the ED setting. c-FLOW™ values suggest variable and dynamic CBF during CPR. c-FLOW™ values do not appear to correlate with PetCO
2
but appear to detect increases in CBF associated with vasopressor therapy during CPR. Future studies are needed to determine the value of continuous non-invasive CBF monitoring as part of a goal-directed strategy to optimize brain resuscitation during CPR.
Real time cerebral blood flow monitoring by laser speckle contrast imaging after cardiac arrest with targeted temperature management
