Breathing abnormalities during sleep

The purpose of this communication is to review obstructive and central breathing abnormalities that may occur during sleep, such as obstructive sleep apnea, and Cheyne-Stokes respiration. Emphasis is placed on noninvasive monitoring of the breathing pattern and intrapleural pressure swings by respiratory and surface inductive plethysmography, respectively, which establish the diagnosis of these abnormal breathing patterns.     

Breathing during sleep in normal subjects

Despite considerable data, little is certain about changes in breathing during sleep, let alone possible mechanisms for these changes. This article reviews methodologic problems, including the definition of the normal subject, the definition of the sleep state, and the effects of instrumentation, and discusses data on respiration during REM and NREM sleep in normal humans. Although the evidence is incomplete, respiration during sleep appears fragile, prone to instability, to upper airway obstruction, to hypoventilation, and to ventilation-perfusion mismatch, jeopardizing the homeostatic function of CO2 output and O2 uptake.     

Breathing during sleep in normal pregnant women

Physiologic changes during the last trimester of pregnancy include reduced functional residual capacity and residual volume, increased alveolar-arterial difference for oxygen, and in the supine position reduced cardiac output. In conjunction with sleep-related apnea or hypoventilation, these could lead to maternal oxygen desaturation during sleep. Because we could not find detailed respiratory sleep studies in late pregnancy, we performed complete polysomnography on 6 pregnant women at 36 wk gestation and again postpartum. Contrary to what we expected, oxygenation was well maintained, with neither mean nor minimal arterial oxygen saturation significantly different during pregnancy. Frequency of apnea and hypopnea and total apnea and hypopnea time were significantly reduced during pregnancy. This finding may be due to increased levels of progesterone during pregnancy and may contribute to preservation of maternal oxygenation during late pregnancy.     

Breathing during wakefulness and sleep after human heart-lung transplantation

To study the effects of pulmonary denervation on breathing during sleep, sleep studies were conducted on seven heart-lung transplant recipients (H-LT) and a comparable number of sex-matched normal subjects of similar age. Four of the H-LT patients had a restrictive pattern on spirometry. The time since transplantation ranged from 45 to 1,102 days. There were no significant differences between the groups with respect to total sleep time or distribution of sleep stages. There were no significant differences between the H-LT recipients and normal subjects with respect to baseline awake oxyhemoglobin saturation (SaO2) or the nadirs of SaO2 during REM and non-REM sleep, the absolute number and frequency (number per hour of sleep) of apneas, hypopneas, desaturation events, both over the whole night of study or separately during non-REM and REM sleep. Across wakefulness and all sleep stages, the H-LT patients tended to have shorter total respiratory cycle times (Ttot) (p = 0.052) and more rapid breathing frequency (F) than the normal subjects. This was associated with significantly shorter inspiratory times (Tl) (p less than 0.001) and smaller duty cycles (Tl/Ttot) (p less than 0.005) in the H-LT recipients. During non-REM and REM sleep, F tended to be higher in the H-LT recipients with pulmonary restriction than in the nonrestricted patients. There were no significant differences between the H-LT recipients and the normal subjects with regard to the periodicity of breathing, either in terms of timing parameters or breath amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)     

Breathing during sleep in patients with interstitial lung disease

Patients with interstitial lung disease (ILD) have a rapid shallow breathing pattern while awake that is thought to be due to activation of lung reflexes. We wondered whether sleep would result in changes in respiratory control and thus cause hypoxemia and poor sleep quality. Eleven patients with ILD (5 men and 6 women) and 11 age- and sex-matched control subjects were studied during sleep. Sleep quality was worse in patients with ILD, with more time in Stage 1 (33.7% of total sleep time (TST) versus 13.5%) and less time in REM sleep (11.8 versus 19.9% TST) than found in control subjects, and more fragmentation of sleep (13.7 +/- 3.1 arousals/h and 24.3 +/- 6.0 sleep stage changes/h versus 6.9 +/- 1.0 and 12.7 +/- 1.4, respectively). Patients with ILD with awake SaO2 less than 90% had greater abnormalities in sleep structure than did those with SaO2 greater than 90%. The incidence of apneas and hypopnea periods in patients with ILD was low (apnea plus hypoventilation index of 1.3 +/- 0.45 versus 2.9 +/- 0.82 in control subjects, p = NS). Oxygen saturation dropped during REM sleep in patients, especially in those with more severe awake hypoxemia. Expiratory time (Te), inspiratory time (Ti), and their sum (Ttot) were shorter in the patients, whereas Ti/Ttot was the same as in control subjects. No systematic changes during sleep were seen in these variables. The variability of inspiratory volume index, Ti, Te, and Ti/Ttot was similar to that in control subjects, and was lowest during NREM sleep. The incidence of snoring was comparable in patients and control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Breathing abnormalities during sleep in patients with chronic heart failure

Polysomnography was carried out in 11 adult outpatients with stable chronic heart failure (CHF) due to valvular heart disease in order to investigate respiratory abnormalities during sleep. The subjects consisted of 6 males and 5 females and their ages ranged from 54 to 76 years. A coexisting central dominant sleep apnea syndrome (SAS) was found in 4 males, 3 of whom had evidence of nasal obstruction. A successful mitral valve replacement in one patient with central dominant SAS was associated with a reduction in the frequency of sleep apnea. The results suggest complications caused by respiratory abnormalities during sleep are common and should be considered in the management of patients with CHF.     

阻塞性睡眠呼吸暂停综合征患者睡眠状态下呼吸中枢控制功 …

目的 探讨阻塞性睡眠呼吸暂停综合征（ＯＳＡＳ）患者上气道阻塞与睡眠状态下呼吸中枢控制功能的低下是否有关，方法 通过经鼻气管插管建立鼻咽通气道测定了１６例重度ＯＳＡＳ患者在清楚状态，非快动眼（ＮＲＥＭ）Ｉ＋Ⅱ睡眠期，Ⅲ＋Ⅳ睡眠期，快速眼（ＲＥＭ）睡眠期的口腔阻断压（Ｐ０．１）低氧反应指标（△Ｐ０．１／△ＳａＯ２，△ＶＥ／△ＳａＯ２）及高二氧化碳反应指标（△Ｐ０．１／△ＳａＯ２，△ＶＥ／△ＳａＯ２）。     

Breathing irregularity during wakefulness associates with CPAP acceptance in sleep apnea

Purpose

Individuals have different breathing patterns at rest, during wakefulness, and during sleep, and patients with sleep apnea are no different. The hypothesis for this study was that breathing irregularity during wakefulness associates with CPAP acceptance in obstructive sleep apnea (OSA).

Methods

From a 2007–2010-database of patients with a diagnostic polysomnography (PSG) and prescribed CPAP (n?=?380), retrospectively, 66 patients who quit CPAP treatment at 6 months were identified. Among them, 27 OSA patients quit despite having no side effects for discontinuing CPAP (Group A) and were compared to a matched group (age, body mass index, and apnea–hypopnea index) with good 6-month CPAP adherence (Group B; n?=?21). Five minutes of respiratory signal during wakefulness at the initial PSG were extracted from respiratory inductance plethysmography recordings, and measured in a blinded fashion. The coefficients of variation (CV) for the breath-to-breath inspiration time (T _i), expiration time (T _e), T _i?+?T _e (T _tot), and relative tidal volume, as well as an independent information theory-based metric of signal pattern variability (mutual information) were compared between groups.

Results

The CV for tidal volume was significantly greater (p?=?0.001), and mutual information was significantly lower (p?=?0.041) in Group A as compared to Group B.

Conclusions

Differences in two independent measures of breathing irregularity correlated with CPAP rejection in OSA patients without nasal symptoms or comorbidity. Prospective studies of adherence should examine traits of breathing stability.     

Breathing pattern and eye movement density during REM sleep in humans

Changes in the density of eye movement during rapid eye movement (REM) sleep are associated with changes in ventilation and ventilatory response in animals. Recent data in patients with chronic obstructive pulmonary disease suggest that periods of frequent eye movements may be associated with hypoxemia during REM sleep. We have therefore investigated the association between eye movements and ventilation and ventilatory pattern in 10 normal men. Expired ventilation was measured using a pneumotachograph attached to a valved face mask with a dead space of 50 ml and incorporating a peripheral CO2 leak detector. Ventilation was reduced (p less than 0.02) in all stages of sleep compared with that during wakefulness, with no difference between the level of ventilation in each sleep stage (awake, 7.18 +/- 0.43 SEM; Stage 2, 6.47 +/- 0.43; Stage 3/4, 6.45 +/- 0.52; REM sleep, 6.55 +/- 0.47 L/min). During REM sleep, eye movements (EMs) were associated with rapid shallow breathing. Dividing REM into 20-s epochs with or without EMs, EMs were associated with a raised breathing frequency (no EMs, 14.4 +/- 0.4 breaths/min; EMs, 15.8 +/- 0.5 breaths/min; p = 0.01), reduced tidal volume (0.49 +/- 0.03 L; 0.41 +/- 0.03 L; p less than 0.01), and reduced minute ventilation (6.87 +/- 0.45 L; 6.27 +/- 0.51 L; p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Breathing during sleep in stable asthmatic subjects. Influence of inhaled bronchodilators

The bronchoconstriction of asthma displays a circadian rhythm with exacerbations often occurring in the early morning hours. Gas exchange abnormalities during sleep in patients with severe asthma have been documented; however, the influence of sleep on gas exchange in the asthmatic with few or no daytime or nocturnal symptoms is poorly understood. To determine if abnormalities in oxygenation might occur during sleep, we studied 12 stable adult asthmatic patients with reversible airflow obstruction during sleep on three consecutive nights, with night 1 being for acclimatization. On test nights 2 and 3, the subjects received, in random double-blind fashion, either inhaled fenoterol or its placebo. Spirometry was performed before and after bronchodilator treatment and on the next morning. The mean FEV1 was 63 percent predicted before treatment. There was significant (p less than 0.05) improvement in FEV1 on fenoterol night after treatment which was also present the next morning. Mean prefenoterol FEV1 was 2.04 +/- .15 (SEM) and increased to 2.61 +/- .17 after the bronchodilator. The mean morning FEV1 was 2.27 +/- .20. Mean preplacebo FEV1 was 2.07 +/- .12 and did not change significantly with placebo bronchodilator. Sleep analysis demonstrated no significant differences in total sleep time or duration of oxyhemoglobin desaturation between nights. The incidence of sleep disordered breathing was very low (0.14 apneas/hour). The frequency of apneas and hypopneas did not change significantly with treatment. Two of the 12 subjects experienced an asthma attack on placebo night which did not recur following active bronchodilator administration. We conclude that stable asthmatic patients with few nocturnal complaints have a low frequency of disordered breathing and desaturation events during sleep.     

Breathing and oxygenation during sleep are similar in normal men and normal women

Most patients with the sleep apnea syndrome are male, and it has been suggested that there is a fundamental sex difference in breathing during sleep. To explore this we measured overnight ear oxygen saturation (SaO2), breathing patterns, and electroencephalographic sleep stage in 21 healthy nonobese women (10 premenopausal, 11 postmenopausal) and in 19 healthy nonobese men of similar age. Sleep duration averaged 6 h 51 min (range 343 to 468 min). The 21 older (greater than 45 yr) subjects had more episodes of apnea and hypopnea (p less than 0.01) and became more hypoxemic (p less than 0.02) than did the 20 younger subjects, but there was no sex difference, either in the younger or older subjects, in irregular breathing or nocturnal hypoxemia. Seven subjects 51 to 68 yr of age (4 men and 3 women) had more than 30 episodes of apnea and/or hypopnea and/or SaO2 decreases below 90%, but the clinical importance of this finding is unclear, 6 of the 7 being alive and 5 asymptomatic at an average of 47 months (range 5 to 67) later. Thus, irregular breathing and hypoxemia during sleep are common in both sexes older than 50 yr of age. Previous reports of a sex difference are probably explained by poor matching of the men and women, particularly with regard to body weight.     

Breathing during sleep in patients treated for obstructive sleep apnea. Nasal CPAP for only part of the night

To determine whether long-term NCPAP therapy influences severity of sleep disordered breathing during the second part of a night when NCPAP is applied for only the first four hours of sleep, we studied 21 patients with OSA receiving NCPAP therapy for 253 +/- 41.6 days. Results from polysomnography for the period after withdrawal from NCPAP (night B) were compared to the corresponding period of sleep prior to initiation of NCPAP therapy (night A). There was no significant change in RDI from night A (53.9 +/- 8.6) to night B (28.7 +/- 3.3), but maximal apnea length diminished from 55 +/- 2.9 s to 40 +/- 2.9 s (p less than 0.05). Whereas daytime Po2 and the amplitude of desaturations during sleep remained equal, overall oxygenation during sleep improved slightly (mean SaO2 night A = 90.6 +/- 0.9 percent; night B = 92.8 +/- 0.5 percent; p less than 0.05). Differences between nights A and B were more prominent the more severe sleep apnea had been prior to treatment and could not be explained by weight loss. There was strong correlation between improvements in oxygenation measurements and the daily time of NCPAP use. In conclusion, we found a subgroup of OSA patients receiving long-term NCPAP therapy with less disturbed ventilation during sleep following use of NCPAP for only the first part of the night, but in the majority of patients, sleep disordered breathing off NCPAP remained unchanged.     

Effect of nasal or oral breathing route on upper airway resistance during sleep.

Healthy subjects with normal nasal resistance breathe almost exclusively through the nose during sleep. This study tested the hypothesis that a mechanical advantage might explain this preponderance of nasal over oral breathing during sleep. A randomised, single-blind, crossover design was used to compare upper airway resistance during sleep in the nasal and oral breathing conditions in 12 (seven male) healthy subjects with normal nasal resistance, aged 30+/-4 (mean+/-SEM) yrs, and with a body mass index of 23+/-1 kg x m2. During wakefulness, upper airway resistance was similar between the oral and nasal breathing routes. However, during sleep (supine, stage two) upper airway resistance was much higher while breathing orally (median 12.4 cmH2O x L(-1) x s(-1), range 4.5-40.2) than nasally (5.2 cmH2O x L(-1) x s(-1), 1.7-10.8). In addition, obstructive (but not central) apnoeas and hypopnoeas were profoundly more frequent when breathing orally (apnoea-hypopnoea index 43+/-6) than nasally (1.5+/-0.5). Upper airway resistance during sleep and the propensity to obstructive sleep apnoea are significantly lower while breathing nasally rather than orally. This mechanical advantage may explain the preponderance of nasal breathing during sleep in normal subjects.     

Breathing pattern of neonates during nonnutritive sucking

Alteration of the breathing pattern seen during oral feeding has been attributed to the behavioral activity of sucking, repeated swallowing, and laryngeal chemoreceptor stimulation. Because it preserves the behavioral activity of sucking but eliminates the laryngeal chemoreceptor stimulation and repeated swallowing that occurs during nutritive sucking, the effects of nonnutritive sucking was evaluated in 19 term infants. The suck-pause pattern seen during nonnutritive sucking is similar to that of nutritive sucking. None of the variables measured (inspiratory duration, expiratory duration, breathing frequency, and tidal volume) were significantly altered during the overall period of nonnutritive sucking when compared with previously obtained control values. These results suggest that the alteration of breathing pattern observed during oral feeding cannot be accounted for by the behavioral activity of sucking per se. However, when the sucking phases of the nonnutritive period were compared with the intervening pauses, a reduction in the expiratory duration (P less than 0.05) and a reduction in tidal volume (P less than 0.05) were observed. Thus, the breathing pattern of human neonates is indeed altered during the sucking phase of the nonnutritive period; pressure changes associated with sucking may account for this alteration.     

Breathing pattern during exercise in untrained children

Breathing pattern during exercise on a cycle ergometer was studied in 18 untrained children aged from 6 to 15 years of age (9 boys, 9 girls). Oxygen uptake, tidal volume, minute ventilation, all normalized for body weight (VO2BW, VT BW, VE BW), respiratory frequency (f), inspiratory (TI) and expiratory (TE) times, ratio TI over total duration of the respiratory cycle (TI/TTOT) and mean inspiratory flow (VT BW/TI) were measured: (1) at rest (W0) and at the highest load (maximal cardiac rate) of an incremental exercise (W1); (2) in steady state conditions, at 50% of W1 (W1/2) and at 2/3 of W1 (W2/3). VO2BW, VT BW, VE BW, TI/TTOT, VT BW/TI increased significantly (P less than 0.01) from W0 to W1. Behaviour of f and TI were different from the latter parameters: f increased and TI decreased significantly from W0 to W1/2 (P less than 0.01) and from W1/2 to W2/3 (P less than 0.01) but remained similar at W2/3 and W1. We observed a relationship between VO2 BW and VT BW/TI, and between VT BW and TI/TTOT at each step of workload. We conclude that untrained children adapt the pattern of breathing during exercise, as at rest, to metabolic demand. However, the increase in f and the decrease in TI are limited at maximal workload.     

Breathing pattern abnormalities and arterial oxygen desaturation during sleep in the congestive heart failure syndrome. Improvement following medical therapy

We observed breathing pattern abnormalities and arterial oxygen desaturation in patients with stable congestive heart failure during overnight polysomnography. To determine whether congestive heart failure was the reason for these abnormalities, we then studied six additional patients before and after treatment of heart failure. Breathing was more abnormal (153 +/- 87 episodes/night) during decompensation of heart failure and improved with medical therapy (72 +/- 100 episodes/night) (p less than 0.05). Abnormal breathing patterns resolved in three patients, improved in two, and were unchanged in one patient after therapy. Allographic cardiac transplantation in one patient whose sleep study remained unchanged after medical therapy was associated with resolution of breathing pattern abnormalities and severe desaturation during sleep. Therapy-related improvement in nocturnal respiratory events suggests congestive heart failure is a contributing factor for breathing abnormalities and arterial oxygen desaturation during sleep.     

Breathing patterns during vaso-occlusive crisis of sickle cell disease

STUDY OBJECTIVES: To determine the effect of sickle cell pain and its treatment on patients' breathing patterns, and to compare the effect of thoracic cage pain to pain at other sites. DESIGN: Prospective, observational study. SETTING: Sickle Cell Center Day Hospital. PATIENTS: Twenty-five patients with sickle cell disease admitted to the Sickle Cell Center Day Hospital for treatment of vaso-occlusive crisis (VOC) [10 patients with chest (thoracic cage) pain]. INTERVENTIONS: Breathing patterns were measured by respiratory inductive plethysmography. Tidal breathing data, including respiratory rate, tidal volume (VT), minute ventilation, and the rib cage contribution to VT, were collected at baseline and then following treatment with opioid analgesia. MEASUREMENTS AND RESULTS: The patients with chest pain had smaller V(Ts) at baseline than those with pain at other sites (355 +/- 37 mL vs 508 +/- 141 mL, p = 0.003), and higher respiratory rates (23.2 +/- 8.2 breaths/min vs 17.6 breaths/min, p = 0.03). These differences became insignificant following opioid treatment. Six patients had respiratory alternans (four patients in the chest pain group, and two patients with pain at other sites). All cases of respiratory alternans resolved following opioid administration. CONCLUSIONS: Patients with VOC and chest pain have more shallow, rapid breathing than patients with pain elsewhere. Analgesia reduces these differences. As pain-associated shallow breathing and maldistribution of ventilation may contribute to the pathogenesis of acute chest syndrome, these results support the need for adequate pain relief and monitoring of ventilatory patterns during the treatment of VOC.