Anaesthetic management of patients with sleep apnoea syndrome

Purpose

Sleep apnoea syndrome (SAS) is a relatively common, potentially fatal, disorder. Patients with SAS exhibit repetitive, often prolonged episodes of apnoea during sleep, with serious nocturnal and diurnal physiologic derangements. Several anecdotal reports and clinical studies have documented anaesthetic-related occurrence of fatal and near-fatal respiratory complications in these patients. The purpose of this article is to outline the potential problems encountered in anaesthetic management of adult SAS patients, and to suggest a practical approach for anaesthesia both for incidental and specific procedures.

Principal findings

SASs have many implications for the anaesthetist. First, SAS patients are exquisitely sensitive to all central depressant drugs, with upper airway obstruction or respiratory arrest occurring even with minimal doses. Thus sedative and opioid premedication should be omitted as should the intra and postoperative use of opioids be limited or avoided. All anaesthetic drugs should be administered by titration to desired effect, preferably using short-acting drugs. When feasible, continuous regional anaesthesia using a catheter is the technique of choice. Where possible nonopioid analgesics or local anaesthetics should be used for postoperative analgesia. Perioperative monitoring for apnoea, desaturation, and dysrhythmias is essential. Secondly, SAS patients have a potentially difficult airway. Awake intubation is the safest approach to airway control. Extubation should only be tried in the fully conscious patient with intact upper airway function and under controlled situations. Thirdly, the cardiorespiratory complications of SAS and the presence of associated diseases can adversely influence anaesthetic management.

Conclusion

Perioperative risks attending SAS patients emphasize the importance of their detection, perioperative evaluation and planning.     

Postoperative management of patients with obstructive sleep apnoea syndrome

Editor—Patients with sleep apnoea are particularly atrisk from the respiratory depressant effects of inhaled anaesthetics,sedatives, and opioids after operation. Reduced upper airwaystone during deeper rapid eye movement (REM) sleep and     

Effects of acetazolamide in patients with the sleep apnoea syndrome.

There is as yet no convincing evidence that acetazolamide, a carbonic anhydrase inhibitor, is effective in obstructive sleep apnoea. A study was therefore designed to examine the effect of acetazolamide (250 mg/day) on sleep events and ventilatory control during wakefulness in nine patients with the sleep apnoea syndrome. In eight of the nine patients the apnoea index and the total duration of apnoea were reduced by acetazolamide, and the mean (SEM) apnoea index of all patients changed from 25.0 (6.7) to 18.1 (5.8) episodes an hour. Furthermore, the total time of arterial oxygen desaturation (SaO2)--more than 4% depression in SaO2 from the baseline sleeping level--divided by total sleep time was also significantly decreased and its mean (SEM) value improved from 24.1 (7.9) to 13.6 (4.8)% of total sleep time. Five of the seven patients with varying degrees of daytime hypersomnolence had their symptoms obviously improved. There was no patient whose predominant type of apnoea was converted from the obstructive to the central type, or vice versa. In the studies of wakefulness, metabolic acidosis, an increase of arterial oxygen tension (PaO2) and a decrease of arterial carbon dioxide tension (PaCO2) were observed. The slopes of the occlusion pressure response and the ventilatory response to carbon dioxide increased, and the carbon dioxide ventilatory response line shifted to the left. It is suggested that acetazolamide cannot remove apnoea completely but has a beneficial effect in mild cases of obstructive sleep apnoea through an augmentation of central (CO2, H+) drive and a stabilising effect on ventilatory control.     

Obstructive sleep apnoea syndrome in children

Obstructive sleep apnoea syndrome in children is a complex disorder characterised by repeated nocturnal episodes of increased upper airway resistive load. It is most commonly associated with adenotonsillar hypertrophy and more children are now presenting for adenotonsillectomy. These children may pose different anaesthetic problems to those having surgery for recurrent infection alone and anaesthetic morbidity and mortality has been reported. In addition, due to the varied symptomatology of the condition, children with unrecognised obstructive sleep apnoea syndrome may present for incidental surgery. This is of importance as patients with undiagnosed obstructive sleep apnoea syndrome may experience additional peri-operative morbidity when undergoing incidental surgery. This article aims to review the aetiology, pathophysiology, clinical presentation and anaesthetic management of children with obstructive sleep apnoea syndrome.     

Sleep . 6: obstructive sleep apnoea/hypopnoea syndrome and hypertension

The use of CPAP to control excessive daytime sleepiness in OSAHS probably also produces a substantial reduction in vascular risk. This is reviewed with particular reference to hypertension.     

Compliance with CPAP therapy in patients with the sleep apnoea/hypopnoea syndrome.

BACKGROUND--Continuous positive airway pressure (CPAP) therapy is the treatment of choice for the sleep apnoea/hypopnoea syndrome. Compliance with this relatively obtrusive therapy has not been well studied. METHODS--Usage of CPAP was investigated in 54 patients with sleep apnoea/hypopnoea syndrome (median 36 (range 7-129) apnoeas + hypopnoeas/hour slept) over the first 1-3 months after starting CPAP therapy. In all cases CPAP usage was monitored by hidden time clocks that indicated for how long the machines were switched on--that is, the CPAP run time. In 32 patients the time at which the CPAP mask pressure was at the therapeutic level of CPAP pressure set for that patient--that is, the mask time--was also monitored. In all patients objective daytime sleepiness was assessed by multiple sleep latency before and after CPAP therapy. RESULTS--The mean (SE) nightly CPAP run time was 4.7 (0.4) hours. There was no correlation between run time and severity of the sleep apnoea/hypopnoea syndrome as assessed by apnoea + hypopnoea frequency or multiple sleep latency, and no correlation between CPAP usage and improvement in multiple sleep latency. Thirty two patients in whom mask time was recorded had therapeutic CPAP pressures for 89% (3%) of their CPAP run times. Patients who experienced side effects from CPAP used their CPAP machines significantly less than those who did not. CONCLUSIONS--Patients with sleep apnoea/hypopnoea syndrome used CPAP for less than five hours/night on average with no correlation between severity of sleep apnoea/hypopnoea syndrome and CPAP usage. Patients who complained of side effects used their CPAP therapy less. It is recommended that, as a minimum, CPAP run time should be regularly recorded in all patients receiving CPAP therapy.     

Pulmonary arterial hypertension in four patients treated by leflunomide

Pulmonary arterial hypertension (PAH) is a rare disorder that can be drug-induced, mostly following treatment by appetite-suppressant drugs. We report four cases of patients who developed PAH following a treatment by leflunomide for rheumatoid arthritis, psoriatic arthritis or undetermined connective tissue disease. All patients described a progressive dyspnea from grade II to IV of NYHA classification; clinical examination found signs of heart failure. PAH was finally diagnosed and confirmed by right heart catheterisation. Haemodynamic explorations found pre-capillary pulmonary hypertension with mean pulmonary arterial pressure above 25 mmHg, and pulmonary capillary wedge pressure under 15 mmHg. Explorations of this pre-capillary pulmonary hypertension were conducted according to international guidelines: pulmonary or chronic thromboembolic aetiologies were excluded after ventilation/perfusion lung scan and high-resolution computed tomography. All other etiologic explorations were negative. Imputability of leflunomide was finally retained. Leflunomide was stopped for all patients; three of them received specific PAH treatments. A favourable clinical and/or haemodynamic evolution was observed for all patients. The conclusions of the investigations conducted by our pharmacovigilance centre were communicated to the European Medicines Agency, leading to the addition of “pulmonary hypertension” in the paragraph “special warning and precautions of use” of the package leaflet of leflunomide.     

Tetraplegic obstructive sleep apnoea patients dilate the airway similarly to able-bodied obstructive sleep apnoea patients

Context/objective: Obstructive sleep apnoea (OSA) develops soon after cervical spinal cord injury (SCI) at rates higher than the general population, but the mechanisms are not understood. This study aimed to determine whether OSA in SCI is associated with altered pharyngeal muscle dilatory mechanics during quiet breathing, as has been observed in the non-SCI injured with obstructive sleep apnoea.Design: Cross sectional imaging study.Setting: Medical research institute.Participants: Eight cervical SCI patients with OSA were recruited and compared to 13 able-bodied OSA patients and 12 able-bodied healthy controls of similar age and BMI.Interventions and outcome measures: 3T MRI scans of upper airway anatomy and tagged-MRI to characterize airway muscle motion during quiet breathing were collected for analysis.Results: Considerable variation in the patterns of inspiratory airway muscle motion was observed in the SCI group, with some participants exhibiting large inspiratory airway dilatory motions, and others exhibiting counterproductive narrowing during inspiration. These patterns were not dissimilar to those observed in the able-bodied OSA participants. The increase in airway cross-sectional area of able-bodied control participants was proportional to increase in BMI, and a similar, but not significant, relationship was present in all groups.Conclusion: Despite the limited sample size, these data suggest that SCI OSA patients have heterogeneous pharyngeal dilator muscle responses to the negative pressures occurring during inspiration but, as a group, appear to be more similar to able-bodied OSA patients than healthy controls of similar age and BMI. This may reflect altered pharyngeal pressure reflex responses in at least some people with SCI.     

The sleep apnoea syndrome and epidural morphine

A patient not known in advance to have the sleep apnoea syndrome (SAS) was administered a combined epidural-general anaesthetic for a proposed radical prostatectomy. After surgery which had to be discontinued due to extensive tumoural spread, morphine 5 mg was administered through the epidural catheter for analgesia. Severe respiratory depression occurred eight hours later and was successfully reversed by repeated injections of naloxone. The potential danger of epidural morphine administration to SAS patients is discussed.     

Obstructive sleep apnoea syndrome in morbidly obese children with tibia vara

Morbid obesity and its association with obstructive sleep apnoea syndrome have been increasingly recognised in children. Orthopaedic surgeons are often the primary medical contact for older children with tibia vara, which has long been associated with obesity, but are unfamiliar with the evaluation and treatment of sleep apnoea in children.We reviewed all children with tibia vara treated surgically at one of our institutions over a period of five years. Thirty-seven patients were identified; 18 were nine years of age or older and 13 of these (72%) had morbid obesity and a history of snoring.Eleven children were diagnosed as having sleep apnoea on polysomnography. The incidence of this syndrome in the 18 children aged nine years or older with tibia vara, was 61%. All these patients required pre-operative non-invasive positive-pressure ventilation; tonsillectomy and adenoidectomy were necessary in five (45%). No peri-operative complications related to the airway occurred.There is a high incidence of sleep apnoea in morbidly obese patients with tibia vara. These patients should be screened for snoring and, if present, should be further evaluated for sleep apnoea before corrective surgery is undertaken.     

Pulmonary arterial hypertension in systemic sclerosis

Pulmonary arterial hypertension (PAH) is a frequent and severe complication of systemic sclerosis (SSc) due to combined vasculopathy and fibrogenesis. Early diagnosis and treatment are highly challenging in SSc-PAH and require referral to an expert PAH centre. Diagnostic algorithms evolved in the last decade. Novel therapeutic options notably targeting pulmonary vascular remodeling are needed.     

Familial glaucoma with sleep apnoea: a new syndrome?

Sleep apnoea was combined with glaucoma in five members of two generations of a family The three surviving members with heavy snoring and glaucoma with intraocular pressure maxima in the morning and a fourth with heavy snoring only all had clinical sleep apnoea. The more severe glaucoma, resistant to surgery and medication, correlated with a greater number and duration of episodes of sleep apnoea. In all those who had recordings made episodes of sleep apnoea tended to occur and be more prolonged in rapid-eye-movement sleep. Oxygen desaturation was greater in rapid-eye-movement sleep and could occur without evidence of impaired respiration. In the third generation of this family there is as yet no evidence of impaired respiration in sleep or of glaucoma.     

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。     

Effect of CPAP therapy on daytime function in patients with mild sleep apnoea/hypopnoea syndrome

BACKGROUND: Continuous positive airway pressure (CPAP) is an effective treatment in patients with moderate and severe sleep apnoea/hypopnoea syndrome (SAHS), but the minimum illness severity at which patients obtain benefit from CPAP is unclear. A study was therefore undertaken to investigate whether CPAP improves symptoms and daytime function in patients with mild SAHS. METHODS: Sixteen consecutively recruited patients with mild SAHS (5.0-14.9 apnoeas + hypopnoeas per hour slept and two or more symptoms of SAHS) participated in a prospective placebo controlled randomised crossover trial to assess the effects of CPAP on symptoms and daytime function. Patients spent four weeks on placebo and four weeks on CPAP, undergoing assessments of sleepiness, symptoms, cognitive performance, and well being on the last day of each treatment. Data from the placebo and CPAP assessments were compared. RESULTS: The mean (SE) objective effective use of CPAP was 2.8 (0.7) hours per night. Significant improvements in symptom score (-1.7 (0.5), p < 0.01), mental flexibility (-14 (5) seconds, p = 0.02), and depression rating (-1.6 (0.8), p = 0.03) on CPAP were observed. However, no significant differences in subjective or objective sleepiness were found. Ten of the 16 patients preferred CPAP and opted to continue with this treatment, although this proportion was non- significant (p > 0.4). The eight patients with best CPAP use showed an additional CPAP related improvement in quality of life (-4.4 (1.8), p = 0.03). Those who complied better with CPAP therapy also had a higher average microarousal frequency (p < 0.01) and apnoea+hypopnoea index (p = 0.02) than the poorer compliers. CONCLUSIONS: The results of this study provide evidence for improvements in symptoms and daytime function for patients with mild SAHS treated with CPAP.