The body responds to surgery not just with a wound, but with its nervous system too.
Modern ERAS protocols (Enhanced Recovery After Surgery) explicitly rely on managing the sympathetic stress response as part of rapid recovery. We explain what the science shows about the autonomic nervous system in the perioperative period — with sources — and where NESA actually fits in.
ERAS isn't a new term for "post-surgical care" — it's a specific physiological strategy.
The goal is measurable: fewer complications, a shorter hospital stay, a faster return to normal life.
A foundational review describes the rationale of ERAS programs precisely through the lens of the surgical stress response: surgical trauma triggers a neuroendocrine and sympathetic response, and enhanced-recovery protocols are explicitly designed to blunt it (Ledowski, "Physiologic considerations of ERAS programs: implications of the stress response", Can J Anaesth, 2014).
Overview information. The specific ERAS management is always determined by the surgical team.
Heart rate variability is becoming an active line of perioperative research.
Preoperative HRV predicts perioperative outcome
A systematic review pools studies across multiple surgical specialties and concludes that lower preoperative heart rate variability is associated with more postoperative complications (Frandsen MN et al., Acta Anaesthesiol Scand, 2022; PMID 35092527).
Modulating the stress response remains an active topic
A recent review discusses modulation of the perioperative stress response as an evolving area of anesthesiology and surgical research (Intensive Care Medicine Experimental, 2026; PMC13153308).
a dynamic marker of surgical stress
In urological surgery, HRV is being studied as a dynamic indicator of surgical stress and a potential predictor of postoperative complications (BJS Open, 2024, zrae097; Scientific Reports, 2024, s41598-024-62930-2).
Sources: Ledowski, "Physiologic considerations of ERAS programs: implications of the stress response", Can J Anaesth, 2014 · Frandsen MN et al., Acta Anaesthesiol Scand, 2022 (PMID 35092527) · Intensive Care Medicine Experimental, 2026 (PMC13153308) · BJS Open, 2024 (zrae097) · Scientific Reports, 2024 (s41598-024-62930-2).
Beyond HRV as a biomarker, researchers are also investigating active neuromodulation of the autonomic system in the perioperative context. A randomized trial shows that brief intraoperative stimulation of the vagus nerve — a different mechanism and a different device from NESA — accelerates postoperative recovery via an autonomic pathway (Kaniusas et al., Frontiers in Neuroscience, 2023; PMC10315581). This shows that the category of "autonomic nervous system neuromodulation in the surgical context" is already being studied seriously — not that the results of one device automatically transfer to another.
Non-invasive modulation of exactly this system.
NESA XSIGNAL® works with controlled microcurrents through the limbs, aimed at the balance between the sympathetic and parasympathetic nervous system. This is the same system that ERAS science treats as a modifiable variable of recovery — the thematic link is real.
When NESA helps the autonomic nervous system regain its balance, it is precisely this restored function of the nervous system itself — not the device — that may contribute to factors related to recovery around surgery: perceived stress, sleep, overall well-being.
In other areas NESA already has measured results — and we have every reason to expect they apply around surgery too.
Below we show what has actually been measured — sleep, night-time heart rate, HRV — and exactly where NESA fits into established ERAS practice: as support for the autonomic regulation that surgery and anaesthesia throw off balance.
Measurable effects on exactly these systems — in other study populations.
Above we saw that heart rate variability and sleep quality are central to perioperative ERAS science. NESA XSIGNAL® has published results precisely in these areas — measured in other study populations, on the same physiological systems.
Heart rate variability (SDNN / vagal tone RMSSD)
In athletes: SDNN from 16 to 51 ms, vagal tone (RMSSD) from 27 to 61 ms — the same markers documented above as a predictor of perioperative outcome (Medina-Ramírez, ULPGC, 2025).
Sleep quality, less daytime sleepiness (−58%)
In dementia patients (Teruel-Hernández et al., Int J Environ Res Public Health, 2023); less night-time waking (−22%) and a lower night-time heart rate (−11%) in professional basketball players (García et al., Frontiers in Physiology, 2022) — sleep and night-time heart rate are precisely the parameters that ERAS protocols track in the days after surgery.
REM sleep phase
in elite athletes (Medina-Ramírez et al., Stresses, 2024) — restorative sleep relevant to the post-surgical period, although the study was not conducted in surgical patients.
The results above come from the official, regularly updated database of published NESA results (nesascience.com, peer-reviewed publications in Frontiers, MDPI/IJERPH, BMC, Can J Urol and others) — measured in other study populations (athletes, dementia patients), on the same physiological systems. Full results map: the "Evidence" section of NESA.html.
NESA supports perioperative autonomic regulation — in step with the ERAS protocol and the surgical team.
Any potential perioperative use requires explicit agreement with the operating surgeon and the anesthesiology team — both before and after the procedure.
Hospital stay, complications and recovery remain within the remit of the established ERAS protocol — NESA fits into it as additional autonomic support, at the team's discretion.
Absolute contraindications (pacemaker, pregnancy, active electrical implants) follow the device's IFU and are checked together with the treating team before any use around surgery.
If you are considering NESA as an additional element in a patient's care around surgery, treat this page as a starting point for discussion. The decision remains entirely in the hands of the operating and anesthesiology team.
Discuss your specific case with us.
For surgeons, anesthesiologists, and rehabilitation specialists: we explain the NESA mechanism, the available protocols, and how to assess whether it is a suitable tool within the patient's overall plan.
Where can I get a NESA session?
The authorised centres in Bulgaria — Sofia, Plovdiv and Pleven — with address, phone and contact person.
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