Forced oscillation technique for the evaluation of severe sleep apnoea/hypopnoea syndrome: a pilot study

The forced oscillation technique (FOT) is a noninvasive method of potential clinical interest for quantitatively assessing airway mechanics during sleep. We investigated the applicability of FOT as a diagnostic tool for noninvasive assessment of airflow obstruction in patients with sleep apnoea/hypopnoea syndrome (SAHS) during sleep. In seven patients previously diagnosed with severe SAHS (mean+/-SD apnoea/ hypopnoea index (AHI) 67+/-14) we performed a full polysomnography (PSG) together with on-line measurement of respiratory impedance (IZI) using FOT. For each patient we determined: 1) number of respiratory events conventionally detected by full PSG, those obtained by FOT and their degree of concordance; and 2) the characteristics and values of IZI during the respiratory events. FOT was well tolerated and easily applied in conjunction with a conventional sleep setup. The mean number of respiratory events x h(-1) detected by PSG and FOT were 55+/-16 and 58+/-17, respectively, with a strong concordance. IZI increased from a baseline of 11+/-4 to 50+/-20 cmH2O x L(-1) x s during apnoea (mean+/-SD). In all but one patient intermittent increases of IZI occurred immediately before each obstructive apnoea. In four patients, the increases of IZI developed at end-expiration whereas in two others occurred during inspiration. During hypopnoea most of the patients showed decreases of IZI during expiration. In conclusion, forced oscillation technique can be used as a noninvasive and complementary tool for the diagnosis of respiratory events and provides an on-line quantitative approach for continuous monitoring of airflow obstruction during sleep in patients with sleep apnoea/hypopnoea syndrome.     

Simultaneous laboratory-based comparison of ResMed Autoset with polysomnography in the diagnosis of sleep apnoea/hypopnoea syndrome

ResMed Autoset (AS) is a simplified diagnosis system for obstructive sleep apnoea/hypopnoea syndrome (OSAS) based on the respiratory flow/time relationship by pressure variation measured through simple nasal prongs. A multicentre prospective trial was used to compare AS and polysomnography (PSG) for diagnosing 95 patients, with suspected OSAS. Physicians gave a pretest probability of the patient having OSAS. The apnoea/hypopnoea index (AHI) was compared between the two methods of diagnosis for the whole population and for subgroups according to the pretest probability. Twenty-four patients had AHI < 15 events x h(-1) on PSG and 19 AHI 15-30, and 52 patients had AHI > or = 30. Correlation between AHI assessed by AS and PSG was r=0.87 for total sleep time (TST), p<0.0001. A Bland and Altman plot gave an agreement between the two methods of +/-40%. For a threshold of AHI > or = 15 events x h(-1) to diagnose OSAS, AS has a sensitivity of 92%, specificity of 79%, positive predictive value of 93% and negative predictive value of 76%. With a pretest probability > or = 80%, sensitivity and positive predictive value were 98 and 100% respectively. Of six false negative, four had a high pretest probability (> 80%) or Epworth score > or = 10. Using these parameters as a criterion for proceeding to PSG after a negative AS study would mean that two apnoeic patients (AHI 20 and 17 events x h(-1) by PSG) would escape detection. The Autoset is useful for the detection of obstructive sleep apnoea but with high pretest probability and a negative Autoset result polysomnography should be performed.     

Residual effect of nCPAP applied for part of the night in patients with obstructive sleep apnoea

The aim of the present study was to assess whether nasal continuous positive airway pressure (nCPAP) treatment, applied for only a few hours at the beginning of the night, has any residual effect on sleep and breathing during the ensuing hours of unassisted sleep in patients with obstructive sleep apnoea syndrome (OSAS). In 27 patients with newly-diagnosed OSAS, effective nCPAP was applied during the first part of the night and then withdrawn. Polysomnographic parameters after nCPAP withdrawal were compared with those of the corresponding part of the diagnostic polysomnography performed a few days or weeks before and with those of the first part of night on nCPAP. After 255+/-63 (mean+/-SD) min of sleep with normalization of sleep and breathing parameters under nCPAP, there was partial improvement of OSAS severity during the remaining 124+/-56 min of nocturnal sleep without treatment; mean oxygen saturation, desaturation index (equivalent to the apnoea/hypopnoea index) and movement arousal index all improved significantly with respect to the diagnostic night (p=0.001). This improvement was not accounted for by a change in sleep architecture. We conclude that there is an improvement in severity of obstructive sleep apnoea syndrome after only 4 h of nasal continuous positive airway pressure. This carryover effect could explain why a number of patients with obstructive sleep apnoea syndrome apply nasal continuous positive airway pressure for only part of the night or not every night.     

Indices from flow-volume curves in relation to cephalometric, ENT- and sleep-O2 saturation variables in snorers with and without obstructive sleep-apnoea

In a group of 37 heavy snorers with obstructive sleep apnoea (OSA, Group 1) and a group of 23 heavy snorers without OSA (Group 2) cephalometric indices, ENT indices related to upper airway collapsibility, and nocturnal O2 desaturation indices were related to variables from maximal expiratory and inspiratory flow-volume (MEFV and MIFV) curves. The cephalometric indices used were the length and diameter of the soft palate (spl and spd), the shortest distance between the mandibular plane and the hyoid bone (mph) and the posterior airway space (pas). Collapsibility of the upper airways was observed at the level of the tongue base and soft palate by fibroscopy during a Müller manoeuvre (mtb and msp) and ranked on a five point scale. Sleep indices measured were the mean number of oxygen desaturations of more than 3% per hour preceded by an apnoea or hypopnoea of more than 10 s (desaturation index), maximal sleep oxygen desaturation, baseline arterial oxygen saturation (Sa,O2) and, in the OSA group, percentage of sleep time with Sa,O2 < 90%. The variables obtained from the flow-volume curves were the forced vital capacity (FVC), forced expiratory and inspiratory volume in 1 s (FEV1 and FIV1), peak expiratory and peak inspiratory flows (PEF and PIF), and maximal flow after expiring 50% of the FVC (MEF50). The mean of the flow-volume variables, influenced by upper airway aperture (PEF, FIV1) was significantly greater than predicted.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acoustic analysis of snoring sound in patients with simple snoring and obstructive sleep apnoea

Snoring, a symptom which may indicate the presence of the obstructive sleep apnoea syndrome (OSA), is also common in the general population. Recent studies have suggested that the acoustic characteristics of snoring sound may differ between simple snorers and OSA patients. We have studied a small number of patients with simple snoring and OSA, analysing the acoustic characteristics of the snoring sound. Seventeen male patients, 10 with OSA (apnoea/hypopnoea index (AHI) 26.2 events x h(-1)) and seven simple snorers (AHI 3.8 events x h(-1)), were studied. Full night polysomnography was performed and the snoring sound power spectrum was analysed. Spectral analysis of snoring sound showed the existence of two different patterns. The first pattern was characterized by the presence of a fundamental frequency and several harmonics. The second pattern was characterized by a low frequency peak with the sound energy scattered on a narrower band of frequencies, but without clearly identified harmonics. The seven simple snorers and two of the 10 patients with OSA (AIH 13 and 14 events x h(-1), respectively) showed the first pattern. The rest of the OSA patients showed the second pattern. The peak frequency of snoring was significantly lower in OSA patients, with all but one OSA patient and only one simple snorer showing a peak frequency below 150 Hz. A significant negative correlation was found between AHI and peak and mean frequencies of the snoring power spectrum (p<0.0016 and p<0.0089, respectively). In conclusion, this study demonstrates significant differences in the sound power spectrum of snoring sound between subjects with simple snoring and obstructive sleep apnoea patients.     

Abnormal autonomic stress responses in obstructive sleep apnoea are reversed by nasal continuous positive airway pressure

Obstructive sleep apnoea (OSA) is associated with abnormalities in autonomic stress tests, which are tests of cardiovascular response in the autonomic nervous system (ANS). The level of abnormality has been related to the level of overnight arterial oxygen saturation (Sa,O2). We have studied ANS function pre- and post-treatment with nasal continuous positive airway pressure (nCPAP) in six males with moderately severe or severe OSA (apnoea/hypopnoea index (AHI) median 51 (range 14-74 events.h-1 of sleep). Tests consisted of heart rate responses to Valsalva manoeuvre, deep breathing, and change of posture from lying to standing. In addition, systolic blood pressure (SBP) response to standing and diastolic blood pressure (DBP) response to handgrip were studied. Each abnormal test (compared to published normal values) scored +1.0 and each marginal test result (90-95% confidence interval for normals) scored +0.5. A total score was calculated for the five tests performed in the evening and morning (maximum score 10 per patient). Patients had been receiving treatment for more than 1 year (median 471 (389-624) days) and objective compliance was monitored by a clock counter in the nCPAP machines. Five of six patients had regularly used nCPAP (mean 7.8 h.night-1) and all showed a normalization in ANS test score: pre-nCPAP 2 (1-4.5), post-nCPAP 0.2 (0-0.5) (p < 0.05, Wilcoxon signed rank test). One poorly compliant subject (No. 6; nCPAP 3 h.night-1) had a deterioration in ANS test score: 1 pre-nCPAP to 1.5 post-nCPAP. The improvement in ANS test score in the five compliant patients was positively correlated with an improvement in mean Sa,O2 during sleep posttreatment. We conclude that successful treatment of obstructive sleep apnoea leads to normalization of impaired autonomic stress responses.     

Obstructive sleep apnoea. Part II: Treatment with a customised dental appliance

The use of dental appliances in the treatment of patients with snoring and obstructive sleep apnoea is an important treatment modality for those patients not severe enough for continuous positive airway pressure (CPAP) or who cannot tolerate this form of treatment. A mandibular advancement splint has been specifically designed to eliminate snoring and obstructive sleep apnoea. The appliance's design parameters included ease of insertion, comfort, and maximum effectiveness. Customised appliances have been designed for dentate, semi-dentate, and edentulous patients. To date, over 100 appliances have been used with a symptomatic improvement in snoring and well-being in over 80 percent of patients. Dental appliances for the treatment of snoring and obstructive sleep apnoea are simple, cost effective, and reversible.     

A method of studying adaptive changes of the oropharynx to variation in mandibular position in patients with obstructive sleep apnoea

The aim of this study was to develop a method of studying the effects of mandibular advancement on oropharyngeal airway dimensions in the sagittal plane in conscious, supine patients. Six white, dentate, male patients with proven obstructive sleep apnoea had sagittal fluoroscopic recordings taken in the resting supine position. Images were recorded at four frames per second as the mandible was advanced with the teeth in contact to maximum protrusion and then opened. Software in the fluoroscopic imaging system permitted measurement of the change in mandibular position together with oropharyngeal airway dimensions expressed as the narrowest dimension observable in the post-palatal and post-lingual sites. Plotting of airway dimensions during mandibular advancement enabled estimation of the degree of protrusion associated with maximal airway benefits. Progressive mandibular advancement produced variable adaptive changes in the post-palatal and post-lingual regions of the oropharynx. The amount of airway opening appeared to be related to the horizontal and vertical relationships of the face and to the dimensions of the soft palate. The changes in post-palatal and post-lingual airway dimensions were not always identical, despite the observation that both tongue and soft palate were seen to move in unison, with close contact being maintained between the two structures. Jaw opening resulted in synchronous posterior movement of both tongue and soft palate, with consequent narrowing of oropharyngeal airspace. Fluoroscopy is a simple method of assessing upper airway changes with mandibular advancement in the conscious patient. The technique should facilitate the selection of subjects for whom mandibular advancement would seem advantageous. The nature of the adaptive response is dependent on individual structural variation. It is suggested that, where artificial mandibular advancement with dental devices is considered beneficial, jaw opening should be kept to a minimum.     

Immune response to a single bout of exercise in young and elderly subjects

Mandibular advancement splints are successful in managing obstructive sleep apnoea (OSA) in selected subjects. For these to be effective, some improvement in the dimensions of the oropharyngeal airway must occur. Twenty subjects with proven obstructive sleep apnoea were examined using lateral cephalometric radiography and a fluoroscopic technique. Cephalograms were analysed, and assessed for both skeletal and soft tissue abnormalities known to be present in OSA subjects. On the basis of these, a prediction was made as to whether the subject's oropharyngeal airway would increase during mandibular protrusion. From the fluoroscopic sequences, the narrowest antero-posterior dimensions of the post-palatal and post-lingual airways were recorded as the mandible moved from the intercuspal position into maximal protrusion. The changes in airway size were noted and these were compared with the predictions made from the static films. In nine subjects, fluoroscopy indicated that the airway opened well during mandibular protrusion, seven did not improve and in four the changes were minimal. Post-palatally the mean airway increase was 2.6 mm, whilst behind the tongue a mean improvement of 3.1 mm was seen. In all but two instances, the cephalometric prediction agreed exactly with the outcome demonstrated by fluoroscopy. All subjects whose airways clearly increased were correctly identified by the cephalogram alone. Cephalometric features associated with a good airway response to protrusion were a reduced lower facial height, low maxillomandibular planes angle and a high hyoid position, accompanied by a normal anteroposterior relationship of the jaws, relatively normal mandibular body length and soft palate area. The more abnormal the skeletal and soft tissue dimensions, the poorer the prognosis. Thus, whilst a single radiograph could indicate whether a positive mandibular response to protrusion could be expected, where doubt existed, a fluoroscopic analysis could provide a useful adjunct to diagnosis.     

5-oxo-6,8,11,14-eicosatetraenoic acid is a potent stimulator of L-selectin shedding, surface expression of CD11b, actin polymerization, and calcium mobilization in human eosinophils

PURPOSE: To determine whether a hooked appearance of the soft palate can be seen in awake patients with snoring with or without obstructive sleep apnea syndrome (OSAS) on cephalometric radiographs and computed tomographic (CT) scans. MATERIALS AND METHODS: One hundred thirty-one patients with snoring underwent cephalometric radiography, with which the posterior airway space, soft palate length and width, and distance between the hyoid bone and mandibular plane were measured, and/or pharyngeal CT, with which the luminal areas of the airway at the naso-, oro-, and hypopharyngeal levels were measured. RESULTS: Of the 131 patients, 96 had OSAS, and 35 had snoring. Nine of 96 patients with OSAS had soft palate hooking on awake pharyngeal CT or cephalometric images. No patient with snoring alone had hooking. Patients with hooking had a larger posterior airway space than did patients with OSAS without hooking (P = .05), and an enlarged (> or = 15-mm) posterior airway space was more frequent in patients with hooking (eight of nine patients) than in those without hooking (34 of 87) (P < .01). Oropharyngeal and hypopharyngeal areas were significantly larger in patients with hooking than in patients without hooking or in patients with snoring (P < or = .04). CONCLUSION: Cephalometric radiography and CT can demonstrate hooking of the soft palate in awake patients. This finding indicates a high risk for OSAS.     

Auto-CPAP treatment in obstructive sleep apnea syndrome: a prospective randomized study during initiation of treatment

OBJECTIVE: The efficacy and acceptance of self-regulated continuous positive airway pressure (auto-CPAP) ventilation was compared with conventional CPAP administration in the treatment of patients with obstructive sleep apnoea. PATIENTS AND METHODS: Using a cross-over design, under polysomnographic monitoring in a sleep laboratory, 25 patients with obstructive sleep apnoea underwent conventional CPAP or auto-CPAP treatment. Using a questionnaire, patients gave their assessment of its acceptability and efficacy after each treatment session. RESULTS: The mean pressure during treatment was the same in the two groups (7.2 +/- 1.9 versus 7.1 +/- 1.9 mbar; no significant difference). Maximal pressure during auto-CPAP averaged 3.7 +/- 2.1 mbar higher than during conventional CPAP ventilation. The mean apnoea-hypopnoea index (AHI) during auto-CPAP, 4.4 +/- 4.3 mbar, during auto-CPAP was significantly higher than during conventional CPAP treatment (2.8 +/- 2.8 mbar; P = 0.044). In eight patients on auto-CPAP an AHI of 5 or less could not be reached, while an AHI of 5 or less was obtained in all but three patients under conventional CPAP. In a subgroup of 17 patients, in whom a reduction of AHI to at most 5 was achieved with both conventional and auto-CPAP, analysis of sleep pattern and of arousals was similar with the two forms of ventilation. Several patients reported that with auto-CPAP falling in sleep was more difficult and they slept less well. None of the patients preferred auto-CPAP. CONCLUSION: By means of the auto-CPAP neither a pressure reduction nor an improvement in compliance could be achieved. Therapeutic effectiveness was significantly less as with conventional CPAP therapy.     

Screening obstructive sleep apnoea syndrome by home videotape recording in children

Overnight polysomnography (PSG) has been used to diagnose and assess the severity of obstructive sleep apnoea syndrome (OSAS) in children. The aim of this study was to determine whether home video-recording of children during sleep may be used for screening OSAS. In 58 children suspected of having OSAS, PSG results were compared with the corresponding analyses of 30 min video-recordings of each child sleeping at home. The video-recordings were evaluated by: 1) overall investigator's clinical judgement; and 2) a scoring system based on noisy breathing, movements, walking episodes, apnoea, chest retractions and mouth breathing. PSG results were highly correlated with the video test results, with agreement in 49 out of 58 (84%). In 36 of the 58 children, the PSG was abnormal compared with 41 out of 58 abnormal video tests. The sensitivity of the overall investigator judgement of video test was 94% (34 out of 36) and the specificity 68% (15 out of 22). Video scores > 10 were highly predictive of OSAS, whilst scores < 5 were associated with normality. Using a stepwise logistic regression analysis, each of the scoring variables was tested against the PSG results and an equation was formulated for predicting PSG by the video test. The equation predicted PSG results in 49 out of 58 (84%) cases. Thirty minutes of home video-recordings during sleep is a reliable screening method for obstructive sleep apnoea syndrome in children. This technique may, thus, improve patient selection for polysomnography.     

Upper airway changes in snorers and mild sleep apnea sufferers after uvulopalatopharyngoplasty (UPPP)

OBJECTIVES: We used upper airway (UA) imaging in 20 patients to determine (1) whether an effective enlargement of the UA is obtained after uvulopalatopharyngoplasty (UPPP), and (2) whether UA modifications explain the results of such surgery. METHODS: Cephalometric measurements were made to assess the posterior airway space, the length and width of the soft palate, and the distance between the hyoid bone and the mandibular plane. Pharyngeal CT measured the airway cross-sectional area (CSA) at each 10-mm slice from 10 mm above (-10) to 40 mm below (+40) the hard palate. Polysomnography was performed before and after surgery (10+/-10 [SD] months). Good responders were defined by an apnea-hypopnea index (AHI) of <10 postsurgery or, in patients in whom AHI was initially <10, a reduction of AHI >50% of the initial AHI. RESULTS: Twenty patients (age=45+/-11 years) were studied. For the whole group, the mean body mass index (26+/-4 kg/m2) and AHI (14+/-13 vs 18+/-16/h) were unchanged after UPPP. The results of the surgery were mediocre with 7 good responders (35%) and 13 nonresponders (65%) defined by polysomnographic criteria. The only changes on UA imaging for the group as a whole after UPPP were decrease in length (40+/-6 vs 29+/-5 mm, p< or =0.0006) and increase in width of the soft palate (11.5+/-2.7 vs 13.6+/-3.5 mm, p< or =0.006). The increase or decrease in minimal CSA at the oropharyngeal (OP) level after UPPP was significantly correlated with the change in AHI (r=-0.54, p<0.02). Moreover, the changes in CSA obtained at the OP level were significant only in the patients who responded favorably to UPPP (7 vs 13 nonresponders). CONCLUSIONS: Postoperative OP enlargement is associated with a good outcome of UPPP. Persistent narrowing in nonresponders could be due to the increase in soft palate width after surgery.     

Comparison of partially attended night time respiratory recordings and full polysomnography in patients with suspected sleep apnoea/hypopnoea syndrome

BACKGROUND: Laboratory full polysomnography (PSG) is considered to be the gold standard for the diagnosis of the sleep apnoea/hypopnoea syndrome (SAHS), but it is expensive and time consuming. A study was undertaken to evaluate the diagnostic usefulness of a partially attended night time respiratory recording (NTRR) and a clinical questionnaire in patients with suspected SAHS in comparison with full PSG. METHODS: Seventy six patients (54 men) of mean (SD) age 51 (11.5) years with a body mass index of 31 (5.7) kg/m2 were studied at random on two different nights with full PSG at the sleep laboratory and with NTRR on a respiratory ward. NTRR records oximetry, airflow, chest and abdominal motion. All signals were continuously displayed on a computer screen throughout the night and respiratory events were scored automatically the following morning. All patients completed a clinical questionnaire. RESULTS: Mean values of the apnoea/hypopnoea index (AHI) using NTRR were lower than those obtained with full PSG (22.7 (2.4) versus 32.2 (3) events/hour) which was mainly due to underrecognition of hypopnoeas. Sensitivity and specificity of NTRR for the diagnosis of SAHS were 82% and 90%, respectively, taking as reference AHI > 10 on full PSG (AHI-PSG > 10). The mean (+/-2SD) difference in AHI between the two methods was 9.6 (range -5.4-24.6) (95% confidence interval 6.2 to 13). Symptoms of witnessed apnoeas, impotence, the overall clinical impression of a trained physician, and a neck size over 40 cm were significantly more prevalent in patients with AHI-PSG of > 10, but impotence was the only clinical feature significantly more prevalent in patients with false negative compared with true negative NTRR results that helped to distinguish patients with NTRR < 10 but AHI-PSG > 10. CONCLUSIONS: NTRR is a helpful and easy complementary diagnostic tool in clinical practice because it detects patients with moderate to severe SAHS reasonably well and therefore can be useful for confirming a diagnosis of SAHS and also for treatment decisions. It is suggested that patients with suspicion of SAHS should be initially studied by NTRR. When NTRR is negative, a full PSG should be performed if witnessed apnoeas, impotence, systemic hypertension, ischaemic heart disease, and a trained physician's clinical impression of SAHS are present.     

Should patients with sleep apnoea/hypopnoea syndrome be diagnosed and managed on the basis of home sleep studies?

The purpose of this study was to analyse the validity and the economic efficiency of a portable monitor of respiratory parameters (PMRP), used in a home setting for the diagnosis of sleep apnoea/hypopnoea syndrome (SAHS). Eighty nine patients with suspected SAHS were studied in two settings: in the sleep laboratory using full-polysomnography (full-PSG); and at the patient's home using a PMRP. In the home setting, 50 patients were assisted by a technician and 39 set up the equipment themselves. SAHS (apnoea/hypopnoea index (AHI) >10 events x h(-1) by means of full-PSG) was diagnosed in 75 of the 89 patients. An acceptable agreement was obtained between the AHI measured by full-PSG and PMRP, according to the Bland and Altman method of concordance (mean bias 2.56; 95% confidence interval 3.25). Sensitivity and specificity of PMRP were adequate for diagnostic purposes; however, their values rely on the prior PMRP-AHI cut-off point selected with reference to full-PSG-AHI >10. The clinical therapeutic decision taken after PMRP agreed with that taken with full-PSG in 79 patients (89%). Although 10% of the studies with an individual set-up needed repetition, both of the domiciliary modalities (with and without a technician's intervention) were, economically, about three times more efficient than full-PSG. In conclusion, we believe that patients with a suspected sleep apnoea/hypopnoea syndrome should initially be studied in a home setting with a portable monitor of respiratory parameters, since it is a reliable method with an acceptable cost-effective profile.     

Cor pulmonale due to obstructive sleep apnoea

A 47 year old man with a long history of chronic loud snoring and daytime sleepiness presented with hypercapnic respiratory failure and right ventricular failure. The diagnosis of obstructive sleep apnoea (OSA) leading to the 'obesity-hypoventilation syndrome', was supported by the findings of an overnight cardio-respiratory monitoring during sleep. His symptoms and arterial blood gases improved following treatment with nocturnal nasal continuous positive airway pressure (CPAP).     

Management of simple snoring in adults

The management of simple snoring in adults is reviewed. Snoring is associated with oscillations of the soft palate and adjacent structures, as a consequence of a critically reduced pharyngeal cross-sectional area under conditions of sleep-induced flow limitation. Anatomical and physiological factors resulting in upper airway collapse and snoring are reviewed. The conservative treatment of snoring encompasses weight loss, alcohol and sedatives avoidance, as well as smoking cessation. Nasal obstruction should be relieved, either medically or surgically. If these measures fail, polysomnography should be performed. Patients with obstructive sleep apnoea should be offered nasal continuous positive airway pressure therapy. Uvulopalatopharyngoplasty can be proposed to nonapnoeic snorers, with a good chance of success, as far as reported snoring is concerned. Unfortunately, this has not been confirmed by objective recordings, and long-term results have not been adequately studied.     

Long-term efficacy of dietary weight loss in sleep apnoea/hypopnoea syndrome

Weight loss is associated with clinical improvement in sleep apnoea/ hypopnoea syndrome (SAHS). The aim of this study was to ascertain whether the therapeutic efficacy of dietary weight loss is maintained in the long-term. From a total of 216 overweight SAHS patients treated by only a weight reduction programme, 24 cured by this method (apnoea/hypopnoea index (AHI) at diagnosis 443+/-27.8, after weight loss 3+/-3.1) were re-evaluated after a mean (+/-SD) period of 94.3+/-27.4 months post-cure. No correlation was found between changes in AHI and body mass index experienced by each patient in the two phases of the study (diagnosis to cure and cure to long-term follow-up), r=0.29, p=0.156, demonstrating a marked intra-individual variability. Six of the 13 patients who maintained their weight presented recurrence of SAHS (AHI 40.5+/-24.1) as did eight of the 11 who had regained weight (AHI 44.3+/-23.). Weight maintenance was more frequent among patients who had continued to attend periodic appointments, 10/11 versus 3/13 (p<0.001). In conclusion, weight-loss efficacy is maintained in the long-term in some sleep apnoea/hypopnoea syndrome patients. This study indicates the need for periodic follow-up of these patients as a reinforcement for weight maintenance and for early detection of the reappearance of sleep apnoea/hypopnoea syndrome.     

Concomitant radiotherapy with mitomycin C and bleomycin compared with radiotherapy alone in inoperable head and neck cancer: final report

We evaluated the efficiency of two different treatment procedures with continuous positive airway pressure (CPAP) on sleep, nocturnal breathing characteristics and daytime vigilance in 18 newly diagnosed patients with untreated sleep apnoea/hypopnoea syndrome (SAHS) randomly allocated to two different groups. In group I, the positive pressure (PP) level was set to suppress flow limitation (PFL), while in group II the PP was set at a level that eliminated only apnoea/hypopnoea and snoring (PAHS). At the end of a 3 week period of home CPAP therapy, a follow-up sleep study, vigilance and cognitive tests were made. Overall, PFL was significantly higher than PAHS values (PFL: 10.42.6 cmH2O; PAHS: 8.9+/-2.6 cmH2O; p<0.01, mean+/-SD). We found no difference in sleep quality, nocturnal saturation and apnoea/hypopnoea index, or in daytime vigilance tests between the two groups at the end of the treatment period. However, there was a significantly greater scattering in the changes of sleep latency in group II than in group I. This was associated with a significant difference in the daily duration of nasal CPAP use between the two groups (group I: 7.29+/-0.95 h x day(-1); group II: 6.01+/-0.94 h x day(-1); p=0.01) and with a positive correlation between final maintenance of wakefulness test values and the duration of CPAP use (p<0.05; r=0.55). These results tend to show that correcting flow limitation is associated with a higher observance and a more important efficiency in normalizing daytime vigilance than with conventional nasal continuous positive airway pressure.