First non-invasive magnetic phrenic nerve and diaphragm stimulation in anaesthetized patients: a proof-of-concept study

Abstract

Background Mechanical ventilation has side effects such as ventilator-induced diaphragm dysfunction, resulting in prolonged intensive care unit length of stays. Artificially evoked diaphragmatic muscle contraction may potentially maintain diaphragmatic muscle function and thereby ameliorate or counteract ventilator-induced diaphragm dysfunction. We hypothesized that bilateral non-invasive electromagnetic phrenic nerve stimulation (NEPNS) results in adequate diaphragm contractions and consecutively in effective tidal volumes. Results This single-centre proof-of-concept study was performed in five patients who were 30 [IQR 21–33] years old, 60% (n = 3) females and undergoing elective surgery with general anaesthesia. Following anaesthesia and reversal of muscle relaxation, patients received bilateral NEPNS with different magnetic field intensities (10%, 20%, 30%, 40%); the stimulation was performed bilaterally with dual coils (connected to one standard clinical magnetic stimulator), specifically designed for bilateral non-invasive electromagnetic nerve stimulation. The stimulator with a maximal output of 2400 Volt, 160 Joule, pulse length 160 µs at 100% intensity was limited to 50% intensity, i.e. each single coil had a maximal output of 0.55 Tesla and 1200 Volt. There was a linear relationship between dosage (magnetic field intensity) and effect (tidal volume, primary endpoint, p < 0.001). Mean tidal volume was 0.00, 1.81 ± 0.99, 4.55 ± 2.23 and 7.43 ± 3.06 ml/kg ideal body weight applying 10%, 20%, 30% and 40% stimulation intensity, respectively. Mean time to find an initial adequate stimulation point was 89 (range 15–441) seconds. Conclusions Bilateral non-invasive electromagnetic phrenic nerve stimulation generated a tidal volume of 3–6 ml/kg ideal body weight due to diaphragmatic contraction in lung-healthy anaesthetized patients. Further perspectives in critically ill patients should include assessment of clinical outcomes to confirm whether diaphragm contraction through non-invasive electromagnetic phrenic nerve stimulation potentially ameliorates or prevents diaphragm atrophy.

Breath-by-breath comparison of a novel percutaneous phrenic nerve stimulation approach with mechanical ventilation in juvenile pigs: a pilot study

“…Recently, two feasibility studies by Mueller et al and Panelli et al showed, analog to our data, for electromagnetic-induced PNS alone that lung-protective tidal volumes can be generated by negative pressure inspiration. Although this was demonstrated in both studies for periods of only 10 breaths each in anesthetized humans 16 , 19 . Concordant with our findings, studies in healthy pigs and human ARDS patients showed a tendency in EIT to shift regional lung ventilation from ventral to dorsal and reduce airway pressures using intermittent transvenous PNS augmentation of MV 33 , 35 .…”

Critical illness-associated limb and diaphragmatic weakness

“…Another possibility would be to artificially titrate the inspiratory effort in sedated patients using phrenic nerve stimulation [ 89 ]. Recent studies have reported promising technological developments that may be relevant in critically ill patients [ 90 – 92 ]. The curative approach is to improve the contractile force of the diaphragm in case of weaning failure.…”

Evaluation of phrenic nerve stimulation trigger lag and synchronization in different modes of ventilation

“…Patients on MV for 21 days or longer have high in-hospital mortality and greater post-discharge mortality, healthcare use, and medical costs compared to those with shorter periods of MV ( Hill et al, 2017 ). Phrenic nerve stimulation (PNS) has been proposed during the weaning phase to prevent atrophy of a patient’s diaphragm to help reduce lengthy mechanical ventilation use ( Panelli et al, 2023 ). A primary concern of phrenic nerve stimulation is inducing or exacerbating patient-ventilator discordances, potentially impacting the patient’s respiratory status.…”