Pressure reactivity index correlates with metabolic dysfunction in a porcine model of intracerebral hemorrhage.

Objective: We correlated oxygen, flow, and pressure indices of cerebrovascular reactivity (CR) with extracellular cerebral metabolite concentrations in a porcine model of intracerebral hemorrhage (ICH).

Methods: Continuous advanced multimodal monitoring including microdialysis, cerebral blood flow and P(br)O(2) probes were placed 1 cm in front of the coronal suture in the grey/white matter junction. Following a period of 1 h of monitoring, an autologous arterial ICH with defined volumes (3 mL) was induced. Pressure-, oxygen-, and flow-related autoregulation indices (PRx, ORx, and FRx) were simultaneously calculated and correlated hourly with extracellular cerebral metabolites, including glucose, lactate, pyruvate, and glutamate.

Results: Seventeen swine were monitored on average 12 continuous hours per animal. FRx correlated highly with ORx (0.96, P = <0.001), but values of both FRx and ORx > 0.2 did not correlate with any microdialysis metabolite. Values of PRx > 0.2 correlated highly (0.65, P < 0.001) with the lactate/pyruvate ratio, values of PRx > 0.3 correlated with glutamate (0.67, P < 0.05), the lactate/pyruvate ratio (0.60, P < 0.01), and P(br)O(2) (-0.65, P < 0.01).

Conclusions: We found evidence for impaired CR in a porcine model of ICH. The findings suggest that, among other parameters of CR, positive PRx coefficients have the highest significance and could be associated with microdialysis alterations during hypoxic events.