An Initial Investigation of Diaphragm Neurostimulation in Patients with Acute Respiratory Distress Syndrome.

BACKGROUND

Lung protective ventilation aims at limiting lung stress and strain. By reducing the amount of pressure transmitted by the ventilator into the lungs, diaphragm neurostimulation offers a promising approach to minimize ventilator induced lung injury. This study investigates the physiological effects of diaphragm neurostimulation in acute respiratory distress syndrome (ARDS) patients. The hypothesis was that diaphragm neurostimulation would improve oxygenation, would limit the distending pressures of the lungs and would improve cardiac output.

METHODS

Patients with moderate ARDS were included after 48 hours of invasive mechanical ventilation (MV) and had a left subclavian catheter placed to deliver bilateral transvenous phrenic nerve stimulation. Two 60-minute volume-controlled MV (control) sessions were interspersed by two 60-minute diaphragm neurostimulation sessions delivered continually, in synchrony with the ventilator (MV+STIM). Gas exchange, lung mechanics, chest electrical impedance tomography and cardiac index were continuously monitored and compared across four sessions. The primary endpoint was the PaO2/FiO2 ratio at the end of each session and the secondary endpoints were lung mechanics and hemodynamics.

RESULTS

Thirteen patients were enrolled but the catheter could not be inserted in one, leaving 12 patients for analysis. All sessions were conducted without interruption and well tolerated. The PaO2/FiO2 ratio did not change over the four sessions. Plateau pressure was 23 (20 - 31) cmH2O and 21 (17 - 25) cmH2O, driving pressure was 14 (12 - 18) cmH2O and 11 (10 - 13) cmH2O and end inspiratory transpulmonary pressure was 9 (5 - 11) cmH2O and 7 (4 - 11) cmH2O during MV alone and during MV+STIM session respectively. The dorsal/ventral ventilation surface ratio was 0.70 (0.54 - 0.91) when on MV and 1.20 (0.76 - 1.33) during the MV+STIM session. The cardiac index was 2.7 (2.3 - 3.5) L/min/m 2 on MV and 3.0 (2.4 - 3.9) L/min/m 2 on MV+STIM.

CONCLUSION

This proof-of-concept study showed the feasibility of short-term diaphragm neurostimulation in conjunction with mechanical ventilation in ARDS patients. Diaphragm neurostimulation was associated with positive effects on lung mechanics and on hemodynamics.

Informations de copyright

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Déclaration de conflit d'intérêts

Conflicts of interest: M Dres received personal fees from Lungpacer Medical Inc., Vancouver, Canada and was a member of the Clinical Advisory Board of Lungpacer Medical Inc., Vancouver, Canada. E Rohrs received personal fees from Lungpacer Medical Inc., Vancouver, Canada. S Reynolds is a co-inventor and received personal fees from Lungpacer Medical Inc., Vancouver, Canada. A Demoule reports grants from French Ministry of Health, Assistance publique – Hôpitaux de Paris, Lungpacer, Respinor, consulting fees from Respinor, Lungpacer, Lowenstein, Tribunal administrative de Cergy, Liberate Medical, Payment or honoraria for lectures, presentations from Fisher & Paykel, Baxter, Getinge, Astra, Agence Européenne Informatique, Mindray, outside the submitted work. T Similowski reports personal fees for consulting and teaching activities from ADEP Assistance, AstraZeneca France, Chiesi France, KPL consulting, Lungpacer Inc., OSO-AI, TEVA France, Vitalaire. He is a stock shareholder of startups Hephaï and Austral Dx. He is listed as inventor on issued patents (WO2008006963A3, WO2012004534A1, WO2013164462A1) describing EEG responses to experimental and clinical dyspnea.