Nasal CPAP reduces systemic blood pressure in patients with obstructive sleep apnoea and mild sleepiness

BACKGROUND: A randomised controlled study was undertaken to examine the effect of nasal continuous positive airway pressure (CPAP) on 24 hour systemic blood pressure (BP) in patients with obstructive sleep apnoea (OSA). METHODS: Patients were fitted with an ambulatory BP measuring device as outpatients during normal activities and recorded for 24 hours before starting therapeutic or subtherapeutic (4 cm H(2)O) CPAP treatment. BP monitoring was repeated before completion of 12 weeks of treatment. The primary end point was the change in 24 hour mean BP. RESULTS: Twenty three of 28 participants in each treatment arm completed the study. There was no significant difference between the two groups in age, body mass index, Epworth Sleepiness Score, apnoea-hypopnoea index, arousal index, and minimum Sao(2). Twenty four patients were hypertensive. The pressure in the therapeutic CPAP group was 10.7 (0.4) cm H(2)O. CPAP usage was 5.1 (0.4) and 2.6 (0.4) hours/night for the therapeutic and subtherapeutic CPAP groups, respectively (p<0.001). After 12 weeks of treatment there were significant differences between the two CPAP groups in mean (SE) changes in 24 hour diastolic BP (-2.4 (1.2) v 1.1 (1.0) mm Hg (95% CI -6.6 to -0.5), p = 0.025); 24 hour mean BP (-2.5 (1.3) v 1.3 (1.1) mm Hg (95% CI -7.2 to -0.2), p = 0.037); sleep time systolic BP (-4.1 (2.1) v 2.2 (1.8) mm Hg (95% CI -11.8 to -0.7), p = 0.028); and sleep time mean BP (-3.6 (1.7) v 1.3 (1.4) mm Hg (95% CI -9.2 to -0.4), p = 0.033). CONCLUSIONS: Compared with subtherapeutic CPAP, 12 weeks of treatment with therapeutic CPAP leads to reductions in 24 hour mean and diastolic BP by 3.8 mm Hg and 3.5 mm Hg, respectively, in mildly sleepy patients with OSA.     

Postoperative obstructive sleep apnoea

A 74-year-old man presenting for aortic reconstructive surgery showed severe, previously undiagnosed obstructive sleep apnoea during overnight oximetry monitoring before operation. Postoperatively, in the first 4 hours following extubation, he suffered 238 episodes of respiratory obstruction. These events were associated with frequent arousals, large fluctuations in systolic and diastolic blood pressure. Administration of nasal continuous positive airways pressure abolished the obstructions and allowed an uninterrupted night's sleep, with a significantly reduced blood pressure. Subsequent dips in oxygen saturation as a result of respiratory obstruction recurred on the fifth postoperative night. We conclude that pre-operative overnight oximetry may be useful in identifying those patients at risk of postoperative upper airway obstruction. Use of nasal continuous positive airway pressure may prevent the occurrence of early postoperative obstruction and the associated haemodynamic changes.     

Effect of increased lung volume on sleep disordered breathing in patients with sleep apnoea

BACKGROUND: Previous studies have shown that changes in lung volume influence upper airway size and resistance, particularly in patients with obstructive sleep apnoea (OSA), and that continuous positive airway pressure (CPAP) requirements decrease when the lung volume is increased. We sought to determine the effect of a constant lung volume increase on sleep disordered breathing during non-REM sleep. METHODS: Twelve subjects with OSA were studied during non-REM sleep in a rigid head-out shell equipped with a positive/negative pressure attachment for manipulation of extrathoracic pressure. The increase in lung volume due to CPAP (at a therapeutic level) was determined with four magnetometer coils placed on the chest wall and abdomen. CPAP was then stopped and the subjects were studied for 1 hour in three conditions (in random order): (1) no treatment (baseline); (2) at "CPAP lung volume", with the increased lung volume being reproduced by negative extrathoracic pressure alone (lung volume 1, LV1); and (3) 500 ml above the CPAP lung volume(lung volume 2, LV2). RESULTS: The mean (SE) apnoea/hypopnoea index (AHI) for baseline, LV1, and LV2, respectively, was 62.3 (10.2), 37.2 (5.0), and 31.2 (6.7) events per hour (p = 0.009); the 3% oxygen desaturation index was 43.0 (10.1), 16.1 (5.4), and 12.3 (5.3) events per hour (p = 0.002); and the mean oxygen saturation was 95.4 (0.3)%, 96.0 (0.2)%, 96.3 (0.3)%, respectively (p = 0.001). CONCLUSION: An increase in lung volume causes a substantial decrease in sleep disordered breathing in patients with OSA during non-REM sleep.     

The predictors of central and obstructive sleep apnoea in haemodialysis patients.

BACKGROUND: Sleep apnoea (SA) is often observed in haemodialysis patients, but there have been few studies on types of SA and their predictors. We therefore investigated the prevalence and types of SA and the associations between types of SA and clinical factors in haemodialysis patients. METHODS: We initially examined nocturnal oxygen desaturation index (ODI) (desaturation of >4%/events per hour) in 119 haemodialysis patients (68 males, mean age of 61.4 years). Patients with ODI of more than five were diagnosed as having SA. Then, 30 patients underwent polysomnography and we measured Apnoea-hypopnoea index (AHI), which was calculated as the number of apnoeas plus hypopnoeas per hour of sleep. Clinical characteristics were examined in all patients. RESULTS: Forty-one (34.5%) of the 119 patients had SA. Twenty-seven (22.7%) of the 119 patients had SA with subjective symptoms such as daytime somnolence and snoring. There was a significant difference between body mass index (BMI) in patients with SA and that in patients without SA (22.5 vs 19.8 kg/m2, P<0.001). There were significantly higher prevalences of hypertension (85.4 vs 66.7%, P<0.05) and diabetes mellitus (36.6 vs 10.3%, P<0.01) in patients with SA than those in patients without SA. Multivariable analysis showed that BMI was independently associated with the occurrence of SA (OR 1.20, 95% CI 1.05-1.38). Mean AHI of 30 patients who underwent polysomnography was 53.2+/-28.9 [central apnoea, 4.1+/-5.6 (8%); obstructive apnoea, 21.7+/-21.5 (42%); mixed apnoea, 4.9+/-8.0 (9%); hypopnoea, 21.4+/-15.5 (41%)]. The number of obstructive apnoea events per hour was significantly correlated with BUN (r=0.490, P<0.01), Cr (r=0.418, P<0.05) and BMI (r=0.489, P<0.01) and was inversely correlated with serum bicarbonate (r=-0.646, P<0.01) and brain natriuretic peptide (BNP) (r=-0.481, P<0.01). The number of central apnoea events per hour was correlated inversely with PaO2 (r=-0.393, P<0.05) and PaCO2 (r=-0.388, P<0.05) and tended to be correlated with cardiothoracic ratio (CTR) (r=0.347, P=0.060). CONCLUSIONS: There is a high prevalence of SA in haemodialysis patients. The dominant type of SA in haemodialysis patients is obstructive sleep apnoea (OSA). Uraemia (BUN, Cr), metabolic acidosis (serum bicarbonate) and BMI are good predictors of OSA. PaO2, PaCO2 and CTR are good predictors of central sleep apnoea (CSA). Good management of these factors might improve SA in haemodialysis patients.     

Nasal CPAP therapy: effects of different CPAP levels on pressure transmission into the trachea and pulmonary oxygen transfer

Background: Nasal continuous positive airway pressure (nCPAP) is considered useful for prophylaxis and treatment of respiratory complications following major thoracic surgery. It is unknown, however, which CPAP levels are required to avoid alveolar derecruitment and to consistently improve pulmonary oxygen transfer in patients following thoracotomy. We therefore studied the effects of different nCPAP levels on pressure transmission into the trachea as well as on pulmonary oxygen transfer. Methods: In 10 consecutive patients after cardiac or thoracic vascular surgery, following extubation in the ICU, nCPAP was generated by means of a high‐flow gas source and applied randomly at levels of 5 or 10 cm H₂O. Airway pressure was recorded continuously in the nasal mask and the trachea. The PaO₂/FiO₂ratio was calculated from the tracheal oxygen concentration, and PaO₂ was determined while breathing at an ambient and elevated airway pressure. Haemodynamic variables (heart rate, arterial blood pressure, central venous pressure) were also recorded. Results: Mean pressures in the nasal mask were 5.4±0.1 and 9.7±0.3 cm H₂O. Corresponding tracheal pressures were 2.8±1.0 vs. 7.2±1.1 cm H₂O (P=0.007). With higher mask pressure, the fraction of pressure transferred from the nasal mask into the trachea was larger (0.75±0.03 vs. 0.52±0.05; P=0.04), and tracheal pressures remained positive during the entire respiratory cycle in all patients. In contrast, with 5.4 cm H₂0, negative pressure changes during inspiration occurred in five out of 10 patients. The PaO₂/FiO₂ ratio increased from 183±53 (ambient pressure) to 199±74 (nCPAP 5.4 cm H₂O; P=0.25) and to 333±54 (nCPAP 9.7 cm H₂O; P=0.003). Nasal CPAP did not alter hemodynamics. Conclusion: Nasal CPAP is an effective non‐invasive means of increasing tracheal and thus intrathoracic pressure without adverse hemodynamic effects. Only mask pressures of 9–10 cm H₂O were sufficient to consistently improve pulmonary oxygen transfer in patients following thoracotomy.     

Sildenafil versus continuous positive airway pressure for erectile dysfunction in men with obstructive sleep apnea： a comparat-ive study of their efficacy and safety and the patient＇s satisfaction with treatment

Aim： To assess the efficacy of sildenafil and continuous positive airway pressure （CPAP） in the treatment of concurrent erectile dysfunction （ED） with obstructive sleep apnea （OSA）, and to gauge the level of treatment satisfaction in patients and their partners. Methods： Forty men were treated for 12 weeks with sildenafil 100 mg （20 men） or CPAP during nighttime sleep （20 men）. Treatment efficacy was assessed by the rate of successful intercourse attempts, and satisfaction with treatment was assessed by patients＇ and partners＇ answers to question 1 of the Erectile Dysfunction Inventory of Treatment Satisfaction. Results： Under sildenafil, 128 of 249 （51.4%） intercourse attempts were successful; under CPAP, 51 of 193 （26.9%） attempts were successful （^cp 〈 0.001）. Erectile function was improved in both groups. After sildenafil and CPAP treatment, the mean International Index for Erectile Function domain scores were 14.3 and 10.8, respectively （^bp = 0.025）, compared to 7.8 and 7 at baseline, respectively. CPAP and sildenafil were well tolerated. Sporadic episodes of nasal dryness under CPAP and transient headache and flushing under sildenafil were not significant. Fifty percent of patients treated with sildenafil and 25% with CPAP were satisfied with the treatment, and their partners were equally satisfied. The satisfaction scores for both patients and partners under sildenafil were superior to those under CPAP （^cP 〈 0.002）. Conclusion： Both sildenafil 100 mg and CPAP, used separately, had positive therapeutic impact but sildenafil was superior. Patients and their partners were more satisfied with sildenafil for the treatment of ED. However, because of the high proportion of dissatisfied men and partners, new therapeutic agents or a combination of the two methods must be studied further.     

Obstructive sleep apnoea and anaesthesia

Obstructive sleep apnoea is the most prevalent sleep disorder, affecting up to 5% of the population. It can have profound effects on patients perioperatively and can have a considerable impact on morbidity and mortality. Patients require thorough preoperative assessment including the taking of a detailed history, the use of scoring systems to assess severity (such as the STOP-Bang questionnaire) and physical examination with particular attention to the airway. Elective surgery patients who are deemed to be high risk for OSA should be referred for polysomnography with implementation of CPAP prior to surgery if indicated. Those deemed low risk may be suitable for day surgery. Intraoperative anaesthesia management may include regional anaesthesia, local anaesthetic infiltration or general anaesthesia, depending on the symptoms and the nature of surgery. Particular attention should be paid to a potential difficult airway, the use of short acting agents with a rapid wake up and avoidance of sedatives and opioids. OSA patients have an increased risk of cardiovascular and respiratory postoperative complications. Postoperative management should be based on the severity of OSA, the occurrence of adverse respiratory events in the recovery unit and the need for opioid analgesia.     

Obstructive sleep apnoea and anaesthesia

Obstructive sleep apnoea (OSA) is the most prevalent sleep disorder, affecting up to 5% of the population. It can have a considerable impact upon perioperative morbidity and mortality. Patients require thorough preoperative assessment including a detailed history, the use of scoring systems to assess severity (such as the STOP-Bang questionnaire and the B-APNEIC score) and physical examination, with particular attention to airway assessment. Elective surgical patients who are deemed to be of high risk for OSA should be referred for polysomnography and implementation of continuous positive airway pressure therapy prior to surgery if indicated. Those patients deemed to be of low risk may be suitable for day surgery. Intraoperative anaesthesia management may include regional anaesthesia, local anaesthetic infiltration, or general anaesthesia depending on both patient and surgical factors. Particular attention should be paid to the potential for difficult airway management and avoidance of sedative agents and opioids where possible. Patients with OSA have an increased risk of cardiovascular and respiratory postoperative complications. Postoperative management should be guided by the severity of OSA, the occurrence of adverse respiratory events in the post anaesthesia care unit and the requirement for opioid analgesia.     

Prevalence of obstructive sleep apnoea in men with type 2 diabetes

BACKGROUND: A study was undertaken to establish the prevalence of obstructive sleep apnoea (OSA) in men with type 2 diabetes. METHODS: Men with type 2 diabetes from local hospital and selected primary care practitioner databases received questionnaires about snoring, apnoeas, and daytime sleepiness based on the Berlin questionnaire. Selected respondents had overnight oximetry to establish whether they had OSA. Comparisons of oximetry were made with those from a previous general population study. HbA1c results were collected. RESULTS: 1682 men were sent questionnaires, 56% of whom replied. 57% scored as "high" and 39% as "low" risk for OSA; 4% were already known to have OSA. Oximetry was performed in 240 respondents from both risk groups: 31% of the "high" and 13% of the "low" risk group had significant OSA (more than 10 >4% Sao(2) dips/hour or Sao(2) tracing consistent with OSA). These results were verified by detailed sleep studies. Extrapolation of the oximetry data to the questionnaire respondent population suggests that 23% had OSA. Comparison of the oximetry results with men from a previous general population study (using only more than 10 >4% Sao(2) dips/hour to define OSA) showed the prevalence of OSA is significantly higher in this diabetes population (17% v 6%, p<0.001). Multiple linear regression revealed BMI and diabetes as significant independent predictors of OSA. Following correction for BMI (which explained 13% of the variance in OSA), diabetes explained a further 8% of the variance (p<0.001). There was a low correlation between OSA severity and HbA1c in the subgroup recruited from the hospital database (r = 0.2, p = 0.006) which remained significant after allowing for obesity (p = 0.03). CONCLUSIONS: OSA is highly prevalent in men with type 2 diabetes; most are undiagnosed. Diabetes itself may be a significant independent contributor to the risk of OSA.     

Obstructive sleep apnoea and anaesthesia

Obstructive sleep apnoea is the most prevalent sleep disorder, affecting up to 5% of the population. It can have profound effects on patients perioperatively and can have a considerable impact on morbidity and mortality. Patients require thorough preoperative assessment including the taking of a detailed history, the use of scoring systems to assess severity (such as the STOP-Bang questionnaire) and physical examination with particular attention to the airway. Elective surgery patients who are deemed to be high risk for OSA should be referred for polysomnography with implementation of CPAP prior to surgery if indicated. Those deemed low risk may be suitable for day surgery. Intraoperative anaesthesia management may include regional anaesthesia, local anaesthetic infiltration or general anaesthesia, depending on the symptoms and the nature of surgery. Particular attention should be paid to a potential difficult airway, the use of short-acting agents with a rapid wake up and avoidance of sedatives and opioids. OSA patients have an increased risk of cardiovascular and respiratory postoperative complications. Postoperative management should be based on the severity of OSA, the occurrence of adverse respiratory events in the recovery unit and the need for opioid analgesia.     

持续气道正压通气对阻塞性睡眠呼吸暂停综合征患者勃起功能障碍疗效的meta分析

目的:评价持续气道正压通气(CPAP)对阻塞性睡眠呼吸暂停综合征(OSAS)患者勃起功能障碍(ED)的影响。方法:计算机检索Cochrane Library、PubMed、中国学术期刊全文数据库、中国生物医学文献数据库、万方资源数据库和中国重要会议论文全文数据库并手工检索相关期刊,全面收集CPAP对OSAS合并性功能障碍的临床研究,按照纳入、排除标准选择实验研究并评价质量,而后提取有效数据进行meta分析。结果:最终纳入4篇文献,1篇中文,3篇英文,包括77例患者。meta分析结果显示各研究间无统计学异质性(P=0.80;I2=0%),故采用固定效应模型进行meta分析。结果显示经CPAP治疗后,IIEF-5增高[WMD=4.19,95%(3.01,5.36),P<0.001]。结论:现有临床研究证据显示,对于OSAS合并ED患者,CPAP治疗能明显减轻ED。但因研究质量及研究样本存在明显局限性,期待更多高质量、大规模的临床随机对照研究加以验证。     

NCPAP早产儿鼻塞与鼻罩交替间隔时间的研究

目的 探讨鼻塞与鼻罩2 h和4 h交替降低经鼻持续气道正压通气(NCPAP)早产儿鼻部压力性损伤的效果,为预防早产儿器械相关压力性损伤提供参考。方法 将73例早产儿按随机数字表法分为鼻塞与鼻罩2 h交替组(37例)和4 h交替组(36例),比较两组NCPAP使用时间、用氧浓度、鼻部压力性损伤情况,以及护士工作量。结果 两组鼻部压力性损伤发生率、NCPAP使用时间、用氧浓度比较,差异无统计学意义(均P>0.05),鼻塞与鼻罩4 h交替组的护士工作量显著低于2 h交替组(P<0.05)。结论 NCPAP使用期间鼻塞与鼻罩4 h交替在改善患儿鼻部压力性损伤的结局,提高患儿舒适度与安全性的同时,可减轻护理人员工作量。     

A randomised trial of peri‐operative positive airway pressure for postoperative delirium in patients at risk for obstructive sleep apnoea after regional anaesthesia with sedation or general anaesthesia for joint arthroplasty

Previous pilot work has established an association between obstructive sleep apnoea and the development of acute postoperative delirium 1 - 3 , but it remains unclear to what extent this risk factor is modifiable in the ‘real world’ peri‐operative setting. In a single‐blind randomised controlled trial, 135 elderly surgical patients at risk for obstructive sleep apnoea were randomly assigned to receive peri‐operative continuous positive airway pressure (CPAP) or routine care. Of the 114 patients who completed the study, 21 (18.4%) experienced delirium. Delirium was equally common in both groups: 21% (12 of 58 subjects) in the CPAP group and 16% (9 of 56 subjects) in the routine care group (OR = 1.36 [95%CI 0.52–3.54], p = 0.53). Delirious subjects were slightly older – mean (SD) age 68.9 (10.7) vs. 64.9 (8.2), p = 0.07 – but had nearly identical pre‐operative STOP‐Bang scores (4.19 (1.1) versus 4.27 (1.3), p = 0.79). Subjects in the CPAP group used their devices for a median (IQR [range]) of 3 (0.25–5 [0–12]) nights pre‐operatively (2.9 (0.1–4.8 [0.0–12.7]) hours per night) and 1 (0–2 [0–2]) nights postoperatively (1.4 (0.0–5.1 [0.0–11.6]) hours per night). Among the CPAP subjects, the residual pre‐operative apnoea–hypopnea index had a significant effect on delirium severity (p = 0.0002). Although we confirm that apnoea is associated with postoperative delirium, we did not find that providing a short‐course of auto‐titrating CPAP affected its likelihood or severity. Voluntary adherence to CPAP is particularly poor during the initiation of therapy.     

Measurement of airway pressure during high-flow nasal therapy in apnoeic oxygenation: a randomised controlled crossover trial*

It is recognised that high-flow nasal therapy can prevent desaturation during airway management. Studies in spontaneously breathing patients show an almost linear relationship between flow rate and positive airway pressure in the nasopharynx. Positive airway pressure has been suggested as one of the possible mechanisms explaining how high-flow nasal therapy works. However, data on pressures generated by high-flow nasal therapy in apnoeic adults under general anaesthesia are absent. This randomised controlled crossover trial investigated airway pressures generated by different flow rates during high-flow nasal therapy in anaesthetised and paralysed apnoeic patients, comparing pressures with closed and open mouths. Following induction of anaesthesia and neuromuscular blockade, a continuous jaw thrust was used to enable airway patency. Airway pressure was measured in the right main bronchus, the middle of the trachea and the pharynx, using a fibreoptically-placed catheter connected to a pressure transducer. Each measurement was randomised with respect to closed or open mouth and different flow rates. Twenty patients undergoing elective surgery were included (mean (SD) age 38 (18) years, BMI 25.0 (3.3) kg.m^-2, nine women, ASA physical status 1 (35%), 2 (55%), 3 (10%). While closed mouths and increasing flow rates demonstrated non-linear increases in pressure, the pressure increase was negligible with an open mouth. Airway pressures remained below 10 cmH₂O even with closed mouths and flow rates up to 80 l.min⁻¹; they were not influenced by catheter position. This study shows an increase in airway pressures with closed mouths that depends on flow rate. The generated pressure is negligible with an open mouth. These data question positive airway pressure as an important mechanism for maintenance of oxygenation during apnoea.     

阻塞性睡眠呼吸暂停低通气综合征肥胖患者体质量管理障碍的质性研究

目的了解阻塞性睡眠呼吸暂停低通气综合征(OSAHS)伴肥胖患者体质量管理失败的原因,为提高患者体质量管理的有效性提供参考。方法对17例确诊为OSAHS,需进行体质量管理,但半年后体质量未减轻患者进行深度访谈,采用内容分析法对访谈资料进行整理和分析。结果提练出6个主题:不正确的观念,不了解肥胖与OSAHS的关系,行动力不足,未掌握体质量控制的正确方法,不能继续坚持,无法辨别信息的正确性。结论对OSAHS伴肥胖患者,医务人员应采取多种形式加强针对性的健康教育及督促,以提高患者体质量管理的有效性。     

The relationship between obstructive sleep apnoea and postoperative delirium and pain: an observational study of a surgical cohort

Patients with obstructive sleep apnoea are at increased risk of adverse postoperative outcomes, such as cardiac and respiratory complications. It has been hypothesised that obstructive sleep apnoea also increases the risk for postoperative delirium and acute postoperative pain. We conducted a retrospective, observational study investigating the relationship of obstructive sleep apnoea with postoperative delirium and acute postoperative pain severity. Patients were classified as being at high risk for obstructive sleep apnoea if they had been diagnosed with this condition, or if they were positive for more than four factors using the ‘STOP-BANG’ screening tool. Adjusted logistic regression was used to investigate the association between obstructive sleep apnoea and postoperative delirium, and multivariable linear regression to study the relationship between obstructive sleep apnoea and postoperative pain severity. The incidence of postoperative delirium was 307 in 1441 patients (21.3%; 95%CI 19.2–23.5%). In unadjusted analysis, high risk for obstructive sleep apnoea was associated with delirium, with an odds ratio (95%CI) of 1.77 (1.22–2.57; p = 0.003). After adjustment for pre-specified variables, the association was not statistically significant with odds ratio 1.34 (0.80–2.23; p = 0.27). The mean (SD) maximum pain (resting or provoked) reported for the entire cohort was 63.8 (27.9) mm on a 0–100 mm visual analogue scale. High risk for obstructive sleep apnoea was not associated with postoperative pain severity (β-coefficient 2.82; 95%CI, −2.34–7.97; p = 0.28). These findings suggest that obstructive sleep apnoea is unlikely to be a strong risk factor for postoperative delirium or acute postoperative pain severity.     

Dynamic behaviour of the soft palate during nasal positive pressure ventilation under anaesthesia and paralysis: comparison between patients with and without obstructive sleep-disordered breathing

Background

Difficult mask ventilation is common and is known to be associated with sleep-disordered breathing (SDB). It is our hypothesis that the incidence of expiratory retropalatal (RP) airway closure (primary outcome) during nasal positive pressure ventilation (PPV) is more frequent in patients with SDB (apnea hypopnea index ≥5 h^?1) than non-SDB subjects.