Effects of nighttime non-invasive positive pressure ventilation on respiratory mechanics and sleep disorders in patients with chronic obstructive pulmonary disease

Abstract

Objective To determine the effects of nighttime non-invasive positive pressure ventilation (NIPPV) on respiratory mechanics and sleep disorders in patients with chronic obstructive pulmonary disease(COPD).Methods Sixteen moderate to severe COPD patients during acute exacerbation admitted in Zhujiang Hospital,Southern Medical University,between October 2010 and October 2011 were enrolled in the study.Following spirometry,all the patients who were clinically stable after NIPPV treatment were subjected to respiratory mechanics monitoring and polysomnography (PSG) while breathing spontaneously or receiving NIPPV during sleeping,for capturing warious respiratory and sleep-associated parameters.Results The respiratory rate (RR) did not differ statistically in patients treated with NIPPV as compared to spontaneous breath during sleep (P＞0.05).There were significant increases (all P＜0.05) in tidal volume (VΥ) [(0.35±0.10) L vs (0.45±0.12) L],minute ventilaiion (VE) [(6.17±1.15) L/min vs (7.97±2.34) L/min],mean inspiratory volume (VΥ/Ti) [(0.24+0.09) L/s vs (0.39±0.11) L/s],dynamic lung compliance (CLdyn) [(43.46±12.75) ml/cm H2O (1 cm H2O=98 Pa) vs (60.23±17.31) ml/cm H2O] and pulse oxygen saturation (SpO2) [(83.55±5.07)％ vs (95.67±5.38)％] in NIPPV treatment as compared to spontaneous breath state during sleep.While marked reductions (all P＜0.05) were found in the ratio of inspiratory time to single respiratory cycle(Ti/Ttot) [(0.43±0.11) vs (0.33±0.08)],airway resistance (Raw) [(25.64±6.02) cm H2O/L-1 · S-1 VS (20.34±3.67) cm H2O/L-1.s-1],prcssure-time product (PTP) [(423.12±89.06 cm H2O.s/min vs (170.44 ±41.53) cm H2O.s/min] and end tidal carbon dioxide partial pressure (PETCO2) [(63.74±8.45) mm Hg(1 mm Hg=0.133 kPa) vs (45.32±5.74) mm Hg].In addition,significant increases (all P＜0.05) were present in sleep emciency (SEF％) [(74.23±12.78) ％ to (84.41±15.11)％],the ratio of rapid eye movement duration to total sleep time (REM/TST％) [(12.16±7.38)％ vs (19.35±9.41)％],the ratio of slow wave sleep time to total sleep time (SWS/TST％) [(5.38±3.35)％ vs (13.68±7.25)％],noctumal baseline SpO2 [(84.77 ±4.97)％ vs (96.46±4.32)％] and nocturnal lowest SpO2 [(75.03±6.32)％ vs (85.78±4.84)％]in NIPPV treatment.In contrast,NIPPV resulted in remarkably reduced (all P＜0.05) sleep latency test (SLT) [(63.32±25.26) min vs (30.57±8.02) min],arousal index [(38.24±17.57)/h vs (25.661±5.78)/h],apnea/hypopnea index (AHI) [(3.63±0.76)/h vs (2.51±0.67)/h],the longest time of breathing disorder (BDLon) [(40.02±8.83) s vs (21.37±566) s] and the ratio of the duration when SpO2 ＜90% to total sleep time (SpO2＜90％/TST％) [(29.36±9.74)％ vs (17.72±5.27)％].Conclusions NIPPV may significantly improve respiratory mechanics during sleeping in COPD patients by reducing airway resistance and work of breathing,and hence,ameliorate nocturnal hypoxemia and hypopnca.The quality of sleeping may be impressively improved as a result of altered abnormal sleeping patterns leading to resolved aberrant sleeping. Key words: Pulmonary disease; chronic obstructive; Positive-pressure respiration; Respiratory mechanics; Sleep disorder