[Home mechanical ventilation: indications and pathophysiological limitations].
BACKGROUND
Domiciliary assisted ventilation (DAV) may be undertaken invasively or non-invasively. Non-invasive DAV is used for patients suffering from alveolar hypoventilation due to restrictive pathology. Invasive DAV is reserved for "indications of necessity" that is when non-invasive ventilation is contraindicated due to the absence of adequate cough and for alveolar hypoventilation leading to hypercapnoea during spontaneous ventilation.


BACKGROUND
The main pathophysiological limitation to non-invasive ventilation is the interference of the glottis. In this mode the glottis imposes a variable resistance to the ventilation delivered. Its behaviour is more predictable during Volume controlled than during pressure controlled ventilation. The control parameters of a Volume controlled ventilator are very different from those used in invasive ventilation during which the respiratory system may be regarded as a single compartment (provided a cuffed tube bypasses the upper airway). In non-invasive DAV: mode VCM, tidal volume 13 mls kg(-1), rate 20 cycles min(-1), insp/exp ratio 1/1.2. In invasive DAV: mode VCM, tidal volume 8-10 mls kg(-1), rate 12 cycles min(-1), insp/exp ratio depending on the pathology 1/2.


CONCLUSIONS
As non-invasive DAV is essentially delivered during sleep the parameters for each patient can be optimised during polysomnography because waking, leading to a partial glottic occlusion, interferes with the ventilation delivered.


CONCLUSIONS
Recent understanding of the way the glottis interferes with mechanical ventilation when delivered non-invasively should lead to a revision of earlier practices based on invasive ventilation.
Jounieaux
V
V
Service de Pneumologie et Unité de Réanimation Respiratoire, Centre Hospitalier Universitaire Sud, 80054 Amiens Cedex 1, France. jounieaux.vincent@chu-amiens.fr
Rodenstein
D O
DO
D000075202:Contraindications; D005931:Glottis / Q000503:physiopathology; D006699:Home Care Services / Q000458:organization & administration*; D006801:Humans; D009551:Night Care; D018579:Patient Selection; D017286:Polysomnography; D012121:Respiration, Artificial / Q000009:adverse effects / Q000379:methods*; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D013990:Tidal Volume