title: Diaphragm pacing failure secondary to deteriorated chest wall mechanics: When a good diaphragm does not suffice to take a good breath in.
abstract: Diaphragm pacing allows certain quadriplegic patients to be weaned from mechanical ventilation. Pacing failure can result from device dysfunction, neurotransmission failure, or degraded lung mechanics (such as atelectasis). We report two cases where progressive pacing failure was attributed to deteriorated chest wall mechanics. The first patient suffered from cervical spinal cord injury at age 45, was implanted with a phrenic stimulator (intrathoracic), successfully weaned from ventilation, and permanently paced for 7 years. Pacing effectiveness then slowly declined, finally attributed to rib cage stiffening due to ankylosing spondylitis. The second patient became quadriplegic after meningitis at age 15, was implanted with a phrenic stimulator (intradiaphragmatic) and weaned. After a year hypoventilation developed without obvious cause. In relationship with complex endocrine disorders, the patient had gained 31 kg. Pacing failure was attributed to excessive mechanical inspiratory load. Rib cage mechanics abnormalities should be listed among causes of diaphragm pacing failure and it should be kept in mind that a "good diaphragm" is not sufficient to produce a "good inspiration".
authors.affiliation: AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France.
authors.forename: Lila
authors.initials: L
authors.lastname: Layachi
authors.affiliation: AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France ; INSERM, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France.
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Georges
authors.affiliation: AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France ; INSERM, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France.
authors.forename: Jésus
authors.initials: J
authors.lastname: Gonzalez-Bermejo
authors.affiliation: AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Radiologie Polyvalente, F-75013, Paris, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Brun
authors.affiliation: AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France ; INSERM, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Similowski
authors.affiliation: AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale (Département "R3S"), F-75013, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France ; INSERM, UMR_S 1158 "Neurophysiologie Respiratoire Expérimentale et Clinique", F-75005, Paris, France.
authors.forename: Capucine
authors.initials: C
authors.lastname: Morélot-Panzini
keywords: Ankylosing spondylarthritis; Chronic respiratory insufficiency; Diaphragm pacing; Mechanical ventilation; Obesity; Quadriplegia