Elevated serum neurologic biomarker profiles after cardiac arrest in a porcine model

Abstract

Introduction: Swine exhibit cerebral cortex mitochondrial dysfunction and neuropathologic injury after hypoxic cardiac arrest treated with hemodynamic-directed CPR (HD-CPR) despite normal Cerebral Performance Category scores. We analyzed the temporal evolution of plasma protein biomarkers of brain injury and inflammatory cytokines, as well as cerebral cortical mitochondrial injury and neuropathology for five days following pediatric asphyxia-associated cardiac arrest treated with HD-CPR.

Methods: One-month-old swine underwent asphyxia associated cardiac arrest, 10-20 min of HD-CPR (goal SBP 90 mmHg, coronary perfusion pressure 20 mmHg), and randomization to post-ROSC survival duration (24, 48, 72, 96, 120 h; n = 3 per group) with standardized post-resuscitation care. Plasma neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and cytokine levels were collected pre-injury and 1, 6, 24, 48, 72, 96, and 120 h post-ROSC. Cerebral cortical tissue was assessed for: mitochondrial respirometry, mass, and dynamic proteins; oxidative injury; and neuropathology.

Results: Relative to pre-arrest baseline (9.4 pg/ml [6.7-12.6]), plasma NfL was increased at all post-ROSC time points. Each sequential NfL measurement through 48 h was greater than the previous value {1 h (12.7 pg/ml [8.4-14.6], p = 0.01), 6 h (30.9 pg/ml [17.7-44.0], p = 0.0004), 24 h (59.4 pg/ml [50.8-96.1], p = 0.0003) and 48 h (85.7 pg/ml [61.9-118.7], p = 0.046)}. Plasma GFAP, inflammatory cytokines or cerebral cortical tissue measurements were not demonstrably different between time points.

Conclusions: In a swine model of pediatric cardiac arrest, plasma NfL had an upward trajectory until 48 h post-ROSC after which it remained elevated through five days, suggesting it may be a sensitive marker of neurologic injury following pediatric cardiac arrest.

Keywords: Biomarkers; Cardiac arrest; Neurologic injury; Pediatrics.

Fig. 1

Schematic of experimental protocol. Definitions of abbreviations: CPR = cardiopulmonary resuscitation; ETT = endotracheal tube; VF = ventricular fibrillation; CPR = cardiopulmonary resuscitation; HD = hemodynamic-directed; SBP = systolic blood pressure; CoPP = coronary perfusion pressure; ROSC = return of spontaneous circulation.

Fig. 2

Plasma neurologic injury biomarkers and cytokines. Neurofilament light chain (NfL) is elevated from pre-injury baseline by 1 h, at each sequential point until 48 h and remains elevated at 120 h post CA. Inherent to study design, pre-injury n = 15, 24 h n = 13, 48 h n = 11, 72 h n = 7, 96 h n = 6, 120 h n = 3. No differences are seen between time points for plasma GFAP or cytokine measures.

Fig. 3

Mitochondrial bioenergetic function and mass. There is no significant difference in cerebral cortical mitochondrial function or mass between time points after ROSC.

Fig. 4

Mitochondrial dynamics protein expression and oxidative injury. There is no significant difference in cerebral cortical mitochondrial dynamics via measures of fission (Drp1, Fis1) or fusion (Opa1, Mfn2) relative to GAPDH, or oxidative injury (protein carbonyl, 4-HNE). Western blot protein quantification normalized to GAPDH and presented as relative units.

Fig. 5

Neuropathology quantification of GFAP and Iba1. There is no demonstrable difference in cortical neuropathologic quantification of GFAP (astrocyte reaction) or Iba1 (microglial activation) between time points or relative to sham animals. Values presented as relative units compared to total pixels per image.

Supplementary Fig. 1

Hemodynamic description of asphyxia and cardiac arrest period. Solid lines are means across time; dotted lines represent standard deviations.