title: Effects of doxapram on hypercapnic response during weaning from mechanical ventilation in COPD patients.
abstract: Failure of weaning from mechanical ventilation in COPD patients is often related to diaphragmatic fatigue. Whether there is a central respiratory drive fatigue and a reserve of excitability is still debated. The purpose of this study was to analyze the following in 13 COPD patients weaned from mechanical ventilation: (1) ventilatory (VE/PETCO2) and neuromuscular (P0.1/PETCO2) response to hypercapnia; (2) the maximum reserve capacity measured through changes in the VE/PETCO2 and P0.1/PETCO2 slopes after doxapram (DXP) infusion, which, given during the test, allows measurement of the maximum response capacity to overstimulation; and (3) analyze the influence of these changes on the outcome of weaning. The results show a variable P0.1/PETCO2 response and a low VE/PETCO2. DXP infusion does not change the slopes of these relations but increases the end-expiratory volume (delta FRCd); (p less than 0.02). Since there was no change in the VE/PETCO2, P0.1/PETCO2, and delta FRC values with or without DXP, there was no excitability reserve in patients who were successfully weaned. When weaning failed, DXP did not change VE/PETCO2 and P0.1/PETCO2 slope, but delta FRCd was greater the delta FRC (p less than 0.001). The excitability reserve in these patients leads to an increase in end-expiratory volume, probably worsening the diaphragm dysfunction.
authors.affiliation: Department of Anesthesiology/Critical Care Unit, Université Paris XIII, Bondy, France.
authors.forename: J L
authors.initials: JL
authors.lastname: Pourriat
authors.forename: M
authors.initials: M
authors.lastname: Baud
authors.forename: C
authors.initials: C
authors.lastname: Lamberto
authors.forename: J P
authors.initials: JP
authors.lastname: Fosse
authors.forename: M
authors.initials: M
authors.lastname: Cupa
mesh_terms: D000368:Aged; D002245:Carbon Dioxide / Q000502:physiology; D004315:Doxapram / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D007262:Infusions, Intravenous; D008173:Lung Diseases, Obstructive / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015300:Ventilator Weaning / Q000379:methods
chemical_list: D002245:Carbon Dioxide; D004315:Doxapram