Early neurovascular uncoupling in the brain during community acquired pneumonia

Bernhard Rosengarten,Stefan Kuhnert,Richard Schulz,Dennis Krekel

doi:10.1186/cc11310

Abstract

IntroductionSepsis leads to microcirculatory dysfunction and therefore a disturbed neurovascular coupling in the brain. To investigate if the dysfunction is also present in less severe inflammatory diseases we studied the neurovascular coupling in patients suffering from community acquired pneumonia.MethodsPatients were investigated in the acute phase of pneumonia and after recovery. The neurovascular coupling was investigated with a simultaneous electroencephalogram (EEG)-Doppler technique applying a visual stimulation paradigm. Resting EEG frequencies, visual evoked potentials as well as resting and stimulated hemodynamic responses were obtained. Disease severity was characterized by laboratory and cognitive parameters as well as related scoring systems. Data were compared to a control group.ResultsWhereas visually evoked potentials (VEP) remained stable a significant slowing and therefore uncoupling of the hemodynamic responses were found in the acute phase of pneumonia (Rate time: control group: 3.6 ± 2.5 vs. acute pneumonia: 1.6 ± 2.4 s; P < 0.0005). In the initial investigation, patients who deteriorated showed a decreased hemodynamic response as compared with those who recovered (gain: recovered: 15% ± 4% vs. deteriorated: 9% ± 3%, P < 0.05; control: 14% ± 5%). After recovery the coupling normalized.ConclusionsOur study underlines the role of an early microcirculatory dysfunction in inflammatory syndromes that become evident in pre-septic conditions with a gradual decline according to disease severity.

Highlights

Sepsis leads to microcirculatory dysfunction and a disturbed neurovascular coupling in the brain
The study included 50 patients with Community-acquired pneumonia (CAP); in 43 of these patients, a complete data set of both electrical and hemodynamic recordings was eligible for evaluation
Patients presented at admission with a pneumonia severity index (PSI) score of 99 ± 27, which corresponds to a risk score of IV, and with therapy improved significantly to 86 ± 24 (P < 0.05), which corresponds to a risk score of III

Summary

Introduction

Sepsis leads to microcirculatory dysfunction and a disturbed neurovascular coupling in the brain. To investigate if the dysfunction is present in less severe inflammatory diseases we studied the neurovascular coupling in patients suffering from community acquired pneumonia. A microcirculatory dysfunction was found in many organs such as gut, heart, lung, and brain [6,7,8]. The occurrence of a microcirculatory dysfunction is regarded as an important motor of sepsis-associated organ dysfunction [1,2,3,4,8]. The brain lacks relevant oxygen or energy stores and is highly dependent on an adequate blood supply [13]. The neurovascular coupling (NC) is a brainintrinsic vasoregulatory mechanism that adapts the local cerebral blood flow in accordance with the metabolic needs of active neurons.

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Conclusion