Parasympathetic tone in perioperative and critical care setting: is it a matter?

The parasympathetic nervous system (PNS) has a significant influence on heart rate, stress responses, and immune function [ 1 ]. Alterations in parasympathetic tone during surgery may affect haemodynamic stability, inflammatory response, and recovery, thus increasing risks of mortality, atrial fibrillation, myocardial infarction, and even sepsis although directly related epidemiological data are not available. However, there is a meta-analysis with low quality studies included showing that vagal neuromodulation potentially reduced such complications [ 2 ]. Therefore, the purpose of this editorial is to evaluate the relevance of parasympathetic tone in perioperative and critical care settings, focusing on the effects of parasympathetic tone on clinical outcomes. This includes: 1. The mechanisms by which parasympathetic tone influences cardiovascular and immune responses; 2. Heart rate variability as a surrogate maker of autonomic function; 3. Pharmacological and non-pharmacological interventions to modulate parasympathetic activity; and 4. Potential implications for perioperative patient management.