Abstract
BackgroundThere is an increasing interest in beta-blockade as a therapeutic approach to sepsis following consistent experimental findings of attenuation of inflammation and improved survival with beta1 selective antagonist. However, the mechanism of these beneficial effects remains very uncertain. Thus, this study is aimed at investigating the effects of a beta-1 selective blockade on sympathetic/parasympathetic activity in endotoxin-challenged pigs using heart rate variability. The hypothesis is that an adrenergic blockade could promote parasympathetic activity. Indeed, the increase of parasympathetic activity is a mechanism recently described as beneficial in septic states.MethodsFifty-one endotoxin-challenged pigs were studied. After 30 min of endotoxin infusion and 30 min of evolution without intervention, the pigs were randomly assigned the placebo or esmolol treatment and were observed for 200 min. Overall heart rate variability was assessed continuously, in the temporal domain by standard deviation of RR intervals (SDNN, ms),and in the frequency domain by spectral powers of low frequency (LF, ms2 × 103/Hz) and high frequency (HF, ms2 × 103/Hz) bands.ResultsVariations of power in these frequency bands were interpreted as putative markers of sympathetic (LF) and parasympathetic (HF) activity. In LPS treated animals, Esmolol did not increase SDNN, but instead decreased LF and increased HF power.ConclusionThese spectral modifications associated to a beta-blocker treatment after an endotoxemic challenge are interpreted as a significant decrease of sympathetic activity and an indirect increase of vagal autonomic tone.
Highlights
There is an increasing interest in beta-blockade as a therapeutic approach to sepsis following consistent experimental findings of attenuation of inflammation and improved survival with beta1 selective antagonist
A common way to accurately monitor autonomic nervous system (ANS) is the use of heart rate variability (HRV), which studies electrocardiographic (ECG) fluctuations
A total of 51 animals were included in the study
Summary
There is an increasing interest in beta-blockade as a therapeutic approach to sepsis following consistent experimental findings of attenuation of inflammation and improved survival with beta selective antagonist. This study is aimed at investigating the effects of a beta-1 selective blockade on sympathetic/ parasympathetic activity in endotoxin-challenged pigs using heart rate variability. The increase of parasympathetic activity is a mechanism recently described as beneficial in septic states. Beta-blockers— beta-1 selective antagonists—have demonstrated promising effects in small [1] and large animals [2] with endotoxin/sepsis challenged [3,4,5]. The exact mechanisms underlying the favorable effects of a beta-blockade remain unclear. It could stem from the close interaction between the autonomic nervous system (ANS) and the immune system, which is well recognized [6, 7]. The analysis of the time between two normal QRS complexes, i.e., RR intervals, reflects the parasympathetic and (ortho)sympathetic systems’ activities [8,9,10,11]
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