Table 1: Implications of VNS for anaesthesiologists.
| Scenario | Issues | Management |
| Local issues during VNS activation | Tingling or prickling sensation, hoarseness, sore throat | Resolve with reduction in current intensity Not critical and may lessen over time |
| Cardiac issues | Bradycardia, syncope and rarely cardiac arrest during intra-operative lead testing at implantation | Check the lead placements and connections May need to terminate the procedure |
| Respiratory issues | Altered voice, dyspnoea and cough Increased incidence of obstructive sleep apnoea When using laryngeal mask airways, potential obstruction due to laryngeal musculature contraction | Lower stimulation frequencies, longer period of off time and device inactivation can improve the issues Vigilance for new onset sleep apnoeic symptoms May require VNS to be switched off to reduce the risk of airway obstruction |
| Intra-operative issues | Use of diathermy and therapeutic ultrasound | Short-wave diathermy, microwave diathermy and therapeutic US diathermy should not be used |
| During cardiac arrest | External defibrillation and electrical cardioversion may damage the generator | Use lowest amount of appropriate energy Fibrillation pads to be placed far from the generator and implanted lead Pads should be placed so that current travels in a vector perpendicular to the VNS |
| Magnetic resonance imaging with or without general anaesthesia | Risk of excessive heating of the leads and damage to the stimulator Spurious device stimulation and disruption or VNS system | Discuss with Radiology team looking at the field strength of MRI scan, type of transmit coil, amount of radiofrequency energy and anatomical site of scanning Keep the exclusion zone from C7-L3 vertebrae. Device to be switched off and reprogrammed after scanning |