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Changes in respiration in NREM sleep in hypercapnic chronic obstructive pulmonary disease
Author(s) -
O'Donoghue Fergal J.,
Catcheside Peter G.,
Eckert Danny J.,
McEvoy R. Doug
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.066084
Subject(s) - sleep and breathing , anesthesia , non rapid eye movement sleep , hypercapnia , heliox , medicine , respiratory minute volume , lung volumes , tidal volume , ventilation (architecture) , respiratory system , cardiology , lung , breathing , physics , ophthalmology , eye movement , thermodynamics
Sleep hypoventilation is common in hypercapnic chronic obstructive pulmonary disease (COPD) and may contribute to daytime hypercapnia. The contributions of respiratory drive and respiratory mechanics to alterations in minute ventilation ( V̇ I ) during sleep in this group have not been assessed. We assessed V̇ I , breathing pattern, upper airway and total lung resistance (UAR, R L ), intraoesohageal diaphragmatic EMG (EMG oes ), intrinsic positive end‐expiratory pressure (PEEP i ), dynamic compliance ( C dyn ), pressure–time product of oesophageal pressure (PTP oes ), tension–time index of the diaphragm (TTI di ), end‐expiratory lung volume (EELV) and respiratory drive (assessed as the slope of P oes versus time in the isovolumetric interval before PEEP i is overcome). Measurements were made in wakefulness and non‐rapid eye movement (NREM) sleep, on 76%N 2 /24%O 2 and on 76%He/24%O 2 (heliox). Satisfactory data for analysis were obtained in 10 patients; five had measurements on heliox. V̇ I fell from (mean ( s.e.m. )) 8.84(0.46) to 6.64(0.91 l min −1 , P = 0.011) between wakefulness and stage II sleep, due to a fall in tidal volume. No changes were seen in PEEP i , C dyn , EELV, PTP oes , TTI di , EMG oes or respiratory drive. UAR increased (3.11(0.8) to 10.24(2.96) cmH 2 O l −1 s ( P = 0.013) but R L was unchanged. UAR was reduced on heliox (5.20(1.67) to 3.45(1.35) cmH 2 O l −1 s, P = 0.049) but V̇ I during sleep did not increase. PTP oes (350.2(51.0) to 259.4(46.3) cmH 2 O s min −1 , P = 0.016), TTI di (0.13(0.02) to 0.10(0.02) P = 0.04), and respiratory drive (20.48(4.69) to 15.02(4.57) cmH 2 O s −1 , P = 0.01) were all reduced. This suggests respiratory drive alters to maintain a preset V̇ I in sleep, irrespective of load, at least while the fatigue threshold of respiratory muscles is not exceeded.