title: Air leaks during mechanical ventilation as a cause of persistent hypercapnia in neuromuscular disorders.
abstract: OBJECTIVE
  This study investigated whether air leaks from the upper airway during assisted ventilatory support are associated with persistent hypercapnia (PaCO(2) >45 mmHg) in patients with neuromuscular disorders.
  
  
  METHODS
  A rehabilitation hospital.
  
  
  METHODS
  The study was performed in 95 neuromuscular patients; 52 were tracheostomized with a cuffless tracheostomy tube (invasive ventilation), and 43 received noninvasive ventilation.
  
  
  RESULTS
  The volume of air leaked (VL) and arterial carbon dioxide (PaCO(2)) were routinely measured during mechanical ventilation; PaCO(2) was also measured during spontaneous breathing. VL, expressed as a percentage of tidal volume, was higher in the hypercapnic group (32+/-14%, n=20) than the nonhypercapnic group ( vs. 20+/-14%). PaCO(2) during mechanical ventilation was correlated with both VL and the duration of ventilatory support per day; PaCO(2) during spontaneous breathing was correlated only with the volume of air leaked. In stepwise multiple regression analysis, air leaks contributed to 8% of the variance in PaCO(2) during mechanical ventilation, and daily duration of ventilatory support contributed 5%. In addition, reduction in VL with normalization of PaCO(2) was achieved in five of the noninvasively ventilated patients with persistent hypercapnia by using a chin strap.
  
  
  CONCLUSIONS
  Air leaks during wakefulness are an important cause of persistent hypercapnia in both invasively and noninvasively ventilated neuromuscular patients. However, simple practical measures to reduce the volume of air leaks improve the efficacy of ventilation in these patients.
authors.affiliation: Service de Réanimation Médicale, Hôpital Raymond Poincaré, AP-HP, 92380, Garches, France.
authors.forename: Jesus
authors.initials: J
authors.lastname: Gonzalez
authors.forename: Tarek
authors.initials: T
authors.lastname: Sharshar
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hart
authors.forename: Karim
authors.initials: K
authors.lastname: Chadda
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Raphaël
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lofaso
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000209:etiology* / Q000503:physiopathology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009468:Neuromuscular Diseases / Q000503:physiopathology*; D012121:Respiration, Artificial / Q000009:adverse effects*; D012129:Respiratory Function Tests; D013990:Tidal Volume; D014139:Tracheostomy
chemical_list: D002245:Carbon Dioxide