title: Long-term non-invasive ventilation increases chemosensitivity and leptin in obesity-hypoventilation syndrome.
abstract: BACKGROUND
  Long-term nocturnal non-invasive mechanical ventilation (NIMV) is an effective treatment for obesity-hypoventilation syndrome (OHS), improving central carbon dioxide (CO(2)) sensitivity. Leptin might contribute to sustain adequate ventilation in obesity. The aim of the study was to investigate the role of leptin in the OHS pathogenesis looking at its relationship to CO(2) sensitivity before and after NIMV in OHS patients.
  
  
  METHODS
  In six obese patients (3F/3M; aged 63+/-9 yr; BMI 47.0+/-4.5 kg/m(2)) with OHS and without obstructive sleep apnoea-hypopnoea (OSAH) diurnal arterial blood gases, fasting plasma leptin concentration and CO(2) chemosensitivity were determined before and after 10.3+/-5.6 (range 6-20) months of NIMV.
  
  
  RESULTS
  After NIMV improvements were observed in gas exchange (PaO(2) from 51.3+/-6.7 to 75.0+/-10.3 mmHg, p<0.01; PaCO(2) from 55.5+/-4.8 to 43.7+/-1.2 mmHg, p<0.01; [HCO(3)(-)] from 33.3+/-3.8 to 29.8+/-1.7 mmol/l, p<0.05) and CO(2) chemosensitivity, measured as P(0.1)/PetCO(2) slope (from 0.09+/-0.07 to 0.18+/-0.07 cmH(2)O/mmHg, p<0.05) and V(E)/PetCO(2) slope (from 0.4+/-0.3 to 0.9+/-0.5l/min/mmHg, p=0.07). Plasma leptin increased from 34.5+/-21.1 ng/ml to 50.2+/-22.9 ng/ml (p<0.01) after NIMV and changes of the P(0.1)/PetCO(2) slope correlated with percent changes of plasma leptin (r(2)=0.79, p<0.05).
  
  
  CONCLUSIONS
  These findings suggest a possible role of leptin in the recovery of neuromuscular response to hypercapnia obtained during long-term nocturnal NIMV in OHS patients without OSAH.
authors.affiliation: Respiratory Medicine Unit, University of Brescia, Piazzale Spedali Civili 1, 25100 Brescia, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Redolfi
authors.forename: Luciano
authors.initials: L
authors.lastname: Corda
authors.forename: Giuseppe
authors.initials: G
authors.lastname: La Piana
authors.forename: Sara
authors.initials: S
authors.lastname: Spandrio
authors.forename: Paola
authors.initials: P
authors.lastname: Prometti
authors.forename: Claudio
authors.initials: C
authors.lastname: Tantucci
mesh_terms: D000368:Aged; D000886:Anthropometry; D002245:Carbon Dioxide / Q000097:blood; D002940:Circadian Rhythm; D005215:Fasting / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D020738:Leptin / Q000097:blood* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010845:Obesity Hypoventilation Syndrome / Q000097:blood / Q000628:therapy*; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D010865:Pilot Projects; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*
chemical_list: D020738:Leptin; D002245:Carbon Dioxide; D010100:Oxygen