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Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression
Published on: December 10, 2014
Association Between Deviations From Cerebral Autoregulation-Derived Optimal Blood Pressure and Outcome After
Matthew P Kirschen1, Andrea Lauren Christman Schneider2,3, Tanmay Majmudar4
1Department of Anesthesiology and Critical Care, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania.
Insights
Maintaining optimal mean arterial pressure (MAP) is crucial after pediatric cardiac arrest. Deviations below the personalized optimal MAP (MAPopt) increased unfavorable outcomes, while time above MAPopt correlated with better recovery.
Area of Science:
- Neurology
- Pediatric Critical Care
- Cerebrovascular Physiology
Background:
- Cerebrovascular pressure autoregulation (CAR) is vital for maintaining cerebral blood flow (CBF) but is impaired after cardiac arrest.
- Impaired CAR increases vulnerability to inadequate brain perfusion and oxygen delivery at standard blood pressure guidelines.
- Personalized optimal mean arterial pressure (MAPopt), derived from CAR metrics, can guide therapeutic targets.
Purpose of the Study:
- To investigate the association between deviations from personalized CAR-derived MAPopt and clinical outcomes in pediatric patients post-cardiac arrest.
- To determine if the magnitude and duration of suboptimal mean arterial pressure (MAP) impact patient recovery.
Main Methods:
- Retrospective analysis of prospectively collected data from pediatric patients (≤18 years) post-cardiac arrest.
- Cerebral oximetry index (COx) calculated using near-infrared spectroscopy (StO2) and MAP to assess CAR.
- Multiwindow weighted algorithm determined patient-specific MAPopt over time.
- Logistic regression analyzed associations between MAP deviations (below MAPopt-5 mmHg and above MAPopt) and outcomes.
Main Results:
- 52% of 147 patients experienced unfavorable outcomes.
- A higher burden of MAP < MAPopt-5 mmHg was significantly associated with increased odds of unfavorable outcomes (OR 2.4).
- Longer duration of MAP > MAPopt was significantly associated with increased odds of favorable outcomes (OR 2.5).
Conclusions:
- Greater deviation below personalized MAPopt after pediatric cardiac arrest is linked to worse outcomes.
- Maintaining MAP above personalized MAPopt may improve recovery prospects in this vulnerable population.
Background And Objectives:
Cerebrovascular pressure autoregulation (CAR) maintains adequate cerebral blood flow (CBF) despite changes in cerebral perfusion pressure. CAR is disrupted after cardiac arrest, making the brain vulnerable to inadequate perfusion and oxygen delivery at population-derived guideline-recommended blood pressures. A metric of CAR can be used to determine the mean arterial pressure (MAP) at which CAR is most preserved, termed the optimal MAP (MAPopt). Our objective was to determine whether deviations above or below personalized CAR-derived MAPopt after pediatric cardiac arrest are associated with outcomes.
Methods:
We conducted a retrospective analysis of prospectively collected data of patients aged 18 years or younger admitted to the pediatric intensive care unit at Children's Hospital of Philadelphia between October 2018 and December 2023 for post-cardiac arrest care. We computed cerebral oximetry index (COx), a metric of CAR, using a moving, linear correlation between time-synchronized brain tissue oxygenation (StO2) from near-infrared spectroscopy and MAP. A multiwindow weighted algorithm determined each patient's MAPopt over time. We compared each patient's MAP with their CAR-derived MAPopt during the first 72 hours after arrest. Unfavorable outcome was defined as a Pediatric Cerebral Performance Category score of 4-6 at hospital discharge with change of ≥1 from baseline. We tested association between burden (combining magnitude and duration) of MAP < MAPopt-5 mm Hg and unfavorable outcome, and between duration of MAP > MAPopt and favorable outcomes using logistic regression models adjusted for age, prearrest developmental disability, and measures of arrest severity.
Results:
Among 147 patients included (median age 4.5 years, interquartile range [IQR] 1.1-11.7 years, 59% male), 52% had unfavorable outcomes. The median time from return of circulation to data collection was 4 (IQR 2.1-8.3) hours. The median burden of MAP < MAPopt-5 mm Hg was greater for the unfavorable outcome group compared with the favorable outcome group (192 [IQR 114-310] vs 147 [IQR 86-199] mm Hg·min/h, p = 0.002). A 1 SD higher burden of MAP < MAPopt-5 was associated with 2.4 times increased odds of unfavorable outcomes (95% CI 1.24-4.51). Patients with favorable outcomes had a longer duration of MAP > MAPopt than patients with unfavorable outcomes (48% [IQR 38-56] vs 40% [IQR 28-52], p = 0.011). One SD higher duration of MAP > MAPopt was associated with 2.5 times increased odds of favorable outcomes (95% CI 1.20-5.13).
Discussion:
Greater burden of MAP < MAPopt-5 mm Hg in the first 72 hours after pediatric cardiac arrest was associated with increased odds of unfavorable outcomes after controlling for potential confounders, and longer duration of MAP > MAPopt was associated with increased odds of favorable outcomes.
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Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.