The Burden of Brain Hypoxia and Optimal Mean Arterial Pressure in Patients With Hypoxic Ischemic Brain Injury After Cardiac Arrest*

Abstract

Objectives: In patients at risk of hypoxic ischemic brain injury following cardiac arrest, we sought to (i) characterize brain oxygenation and determine the prevalence of brain hypoxia, (ii) characterize autoregulation using the pressure reactivity index (PRx) and identify the optimal mean arterial pressure (MAPOPT), and (iii) assess the relationship between MAPOPT and brain tissue oxygenation (PbtO2). Design: Prospective interventional study. Setting: Quaternary intensive care unit. Patients: Adult patients with return to spontaneous circulation (ROSC) greater than 10 minutes and a post-resuscitation Glasgow Coma Score under 9 within 72 hours of cardiac arrest. Interventions: All patients underwent multimodal neuromonitoring which included: (i) PbtO2, (ii) intracranial pressure; (iii) jugular venous continuous oximetry (SjvO2); (iv) regional saturation of oxygen (rSO2) using near-infrared spectroscopy, and (iv) PRx based determination of MAPOPT, lower and upper limit of autoregulation. We additionally collected MAP, end tidal carbon dioxide (ETCO2) and temperature. All data were captured at 300 Hz using ICM+® brain monitoring software. Measurements and Main Results: Ten patients (7 males) were included with a median age 47 (range 20-71) and ROSC 22 minutes (12-36). The median duration of monitoring was 47 hours (15-88) and median duration from cardiac arrest to inclusion was 15 hours (6-44). The mean PbtO2 was 23 mmHg (SD 8) and the mean percentage of time with a PbtO2 below 20 mmHg was 38% (6-100). The mean PRx was 0.23 (0.27) and the percentage of time with a PRx greater than 0.3 was 50% (12-91). The mean MAPOPT, lower and upper of autoregulation were 89 mmHg (11), 82mmHg (8) and 96 mmHg (9), respectively. There was marked betweenpatient variability in the relationship between MAP and indices of brain oxygenation. As the patients' actual MAP approached MAPOPT, PbtO2 increased (p<0.001). This positive relationship did not persist when the actual MAP was above MAPOPT. Conclusions: Episodes of brain hypoxia in HIBI are frequent and perfusion within proximity of MAPOPT is associated with increased PbtO2. PRx can yield MAPOPT, lower and upper limit of autoregulation in patients following cardiac arrest.

Near-Infrared Spectroscopy to Assess Cerebral Autoregulation and Optimal Mean Arterial Pressure in Patients With Hypoxic-Ischemic Brain Injury: A Prospective Multicenter Feasibility Study

“…Importantly, this improvement in rS o 2 did not translate to improved imaging correlates or neurologic outcomes ( 30 ). Our group has recently performed a prospective interventional study of invasive neuromonitoring in patients who remained comatose after cardiac arrest ( 2 ). This study demonstrated that the percentage of time with brain tissue hypoxia (partial pressure of brain tissue oxygen [Pbt o 2 ] < 20 mm Hg) was common, despite average MAP OPT recordings being 89 mm Hg ( 2 ).…”

“…Among survivors, the vast majority of subsequent deaths are directly attributable to HIBI, and less than 50% of survivors have a favorable neurologic outcome, assessed using the Cerebral Performance Category (CPC), 6 months post-arrest ( 1 ). HIBI is characterized by multiple mechanisms that occur in parallel, such as failure of microcirculation, no-reflow cerebral edema, tissue hypoxia ( 2 ), elevated intracranial pressure, and dysfunctional cerebral autoregulation ( 3 , 4 ). As such, maintaining adequate CBF and cerebral oxygen delivery is paramount in post-resuscitation care ( 5 ).…”

Targeted temperature management for postcardiac arrest syndrome

“…Moreover, maintaining a MAP > 80 mm Hg is associated with improved outcomes, even if achieved using a vasopressor [89,106,113,115]. Recently, Sekhon et al [116] reported that the optimal MAP to prevent brain hypoxia in case series with multimodal neuromonitoring is about 80 mm Hg.…”

Mean arterial pressure is associated with the neurological function in patients who survived after cardiopulmonary resuscitation: A retrospective cohort study

“…5 Sekhon et alstudy showed that ischemia and hypoxia were very frequent in patients after CPR, and mean arterial pressure (MAP) was firmly related to oxygenation of brain tissue. 6 At present, studies had shown that the higher the MAP, the less brain damage and the lower the mortality in patients who survived after CPR. 7,8 At the same time, Jakkula et al study shown that MAP was not associated with the markers of brain tissue damage (neuron-specific enolase [NSE] and S100B protein).…”

“…The neurological function of patients with cardiac arrest is related to the sensitivity to ischemic hypoxic brain injury, as well as the duration of cardiac arrest, the quality of cardiopulmonary resuscitation (CPR), the underlying coexisting disease, and post‐resuscitation cerebral tissue perfusion 5 . Sekhon et alstudy showed that ischemia and hypoxia were very frequent in patients after CPR, and mean arterial pressure (MAP) was firmly related to oxygenation of brain tissue 6 . At present, studies had shown that the higher the MAP, the less brain damage and the lower the mortality in patients who survived after CPR 7,8 .…”