Can phrenic stimulation protect the diaphragm from mechanical ventilation-induced damage?

Mechanical ventilation is a prominent lifesaving treatment. It is, however, associated with an array of adverse effects, which include ventilator-associated pneumonias, volume-induced lung injury and, more recently identified, ventilator-induced diaphragm dysfunction (VIDD) [1–3]. VIDD combines diaphragm weakness with muscle fibre atrophy, remodelling and injury. Its mechanisms involve decreased protein synthesis, increased proteolysis, increased oxidative stress and mitochondrial dysfunction [2, 4]. Controlled mechanical ventilation appears to be the main, if not the sole, risk factor for VIDD, which in animal models is attenuated by the maintenance of respiratory efforts (assisted ventilatory modes) [2]. Although the corresponding human evidence is still lacking, this underlies the current notion that ‘‘clinicians should encourage persistent diaphragmatic activity’’ in patients receiving mechanical ventilation [2]. Diaphragm pacing has been proposed as a surrogate for spontaneous respiratory activity when the latter is not compatible with the condition of the patient [2, 5], but this approach has, seemingly, not yet been tested experimentally.