Microarousals in patients with sleep apnoea/hypopnoea syndrome

As medical schools begin to implement their new curricula under the guidance of Tomorrow's Doctors, the authors wish to raise some discussion on the form and content of the special study module (SSM) component. In order to do this they put forward in this paper proposals for an SSM in Medicine and Literature. This course has been designed jointly and will be run concurrently in three Scottish medical schools: Glasgow, Aberdeen and Dundee. Arguments for the course's acceptability to faculties of medicine and to students are discussed and its inclusion in the curriculum in terms of its educational impact, skills training, effect on personal development and broadening of the student's perspective are justified. The course structure, content and assessment procedures are described and a reading list proposed. The General Medical Council points out that SSMs should be seen as opportunities for innovation and this course demands a different educational approach from the standard objectives-led approach of most medical education. A process-led model is more appropriate as it stresses the way that students develop while taking the course rather than the end point reached at its finish.     

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.     

Comparison of polysomnography with ResCare Autoset in the diagnosis of the sleep apnoea/hypopnoea syndrome

BACKGROUND: Increasing referral numbers make the development of simplified accurate methods of diagnosing the sleep apnoea/hypopnoea syndrome highly desirable. The accuracy of one such system--the ResCare Autoset--has been examined. METHODS: Thirty one consecutive patients assessed by polysomnography had simultaneous monitoring of their respiratory pattern using the Autoset system. The Autoset detects episodes of flattening of the flow/time profile using nasal cannulae. RESULTS: There was a good correlation (r = 0.85) between the number of apnoeas+hypopnoeas/hour in bed recorded using polysomnography and the Autoset system. The median difference in such events was 3.1 (95% confidence interval 8.4 to -1.6)/hour in bed. In two patients the Autoset scored 70 apnoeas+hypopnoeas/hour in bed compared with 34 apnoeas+hypopnoeas with 35 arousals/hour in bed by polysomnography; however, this did not alter the diagnostic category of either patient. Autoset gave a sensitivity of 100%, specificity of 92%, positive predictive value of 92%, and negative predictive value of 100%, which was better than oximetry alone. A sleep study using the Autoset system costs 14 pounds compared with 126 pounds for polysomnography. CONCLUSIONS: The Autoset is clinically useful for diagnosing the sleep apnoea/hypopnoea syndrome.     

Mokken scaling of the Epworth Sleepiness Scale items in patients with the sleep apnoea/hypopnoea syndrome

Jeune syndrome (asphyxiating thoracic dystrophy) is a rare inherited disease which is fatal in early childhood in 70% of cases. Severe renal involvement may occur and lead to chronic renal insufficiency in patients who survive respiratory failure. Therefore the opportunity to perform kidney transplantation is quite rare. We report a successful cadaver renal transplantation in a 10-year-old boy with Jeune syndrome type 2.     

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.     

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.     

Upper airway mucosa temperature in obstructive sleep apnoea/hypopnoea syndrome, nonapnoeic snorers and nonsnorers

BACKGROUND: This study was performed to assess chemical shift magnetic resonance imaging (CSMRI) for characterizing adrenal masses in patients with lung cancer, and to compare charges associated with two algorithms for assessing adrenal masses in these patients. METHODS: Forty-two patients with lung cancer underwent both CSMRI (using in-phase and opposed-phase gradient echo images) and computed tomography-guided percutaneous biopsy of adrenal masses. Adrenal-to-spleen signal intensity ratios on the opposed-phase images were correlated with histopathologic results. The normalized charges for two algorithms were compared. In algorithm A, computed tomography-guided biopsy is used first to evaluate an adrenal mass; in algorithm B, CSMRI is used first, followed by computed tomography-guided biopsy only if CSMRI findings are not diagnostic of adenoma. RESULTS: Biopsy showed 24 (57%) adrenal adenomas and 18 (43%) metastases. Chemical shift magnetic resonance imaging was 96% sensitive for adenoma and 100% specific. The average normalized charges associated with algorithm A were $1,905 per patient versus $1,890 with algorithm B. CONCLUSIONS: Initial use of CSMRI in evaluating an adrenal mass in lung cancer patients can obviate biopsy in 55% of patients, and its charges are similar to those for performing computed tomography-guided biopsy in all patients.     

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.     

Value of beat-to-beat blood pressure changes, detected by pulse transit time, in the management of the obstructive sleep apnoea/hypopnoea syndrome

BACKGROUND: Previous studies of oculomotor dysfunction in schizophrenia have tended to concentrate on abnormalities of smooth pursuit eye tracking in chronic medicated patients. We report the results of a study of smooth pursuit, reflexive and antisaccade performance in drug naive and antipsychotic treated first-episode schizophrenic patients. METHODS: Smooth pursuit and saccadic eye movements were recorded in 36 first-episode schizophrenic patients and 36 controls matched for age and estimated IQ. The schizophrenic patients were divided into drug-naive (N = 17) and antipsychotic treated groups (N = 19). RESULTS: Smooth pursuit velocity gain was significantly lower than controls only in the drug-naive patients. The treated patients did not differ significantly from either the controls or the untreated group. In an antisaccade paradigm both treated and drug-naive schizophrenic patients demonstrated an increased number of errors, but only drug-naive patients also demonstrated an increased latency in initiating correct antisaccades. CONCLUSIONS: These impairments are unlikely to be due to a generalized deficit in oculomotor function in the schizophrenic groups, as there were no differences between the groups in saccadic metrics on a reflexive saccade task. The results show that both smooth pursuit and saccadic abnormalities are present at the onset of schizophrenia and are integral to the disorder.     

New frontiers in the management of obstructive sleep apnoea syndrome

BACKGROUND: To report the dynamic magnetic resonance (MR) imaging findings of hepatolithiasis. METHODS: Dynamic MR images (fast spoiled gradient echo sequence with intravenous injection of gadopentate dimeglumine) and computed tomography, cholangiography, or angiography of nine patients with hepatolithiasis are analyzed. RESULTS: All affected hepatic segments showed atrophic changes and contained dilated intrahepatic ducts. These segments showed either iso- or hypointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging. Preferential enhancement was noted throughout all phases of the dynamic study and persisted to delayed T1-weighted imaging in seven patients. In the last two patients, severe atrophic changes made evaluating signal intensity differences and enhancement patterns difficult. CONCLUSION: In addition to intrahepatic stones and biliary dilatation, segmental atrophy, signal intensity differences, and preferential and persistent enhancement are important MR findings of hepatolithiasis.     

Appearance of central apnoea in a patient treated by auto-CPAP for obstructive sleep apnoea

We describe a one-port laparoscopic technique for assisting in Tenchkoff catheter placement and salvaging obstructed ones in patients requiring continuous ambulatory peritoneal dialysis (CAPD). This unique technique enables diagnostic laparoscopy, adhesiolysis, repositioning of catheters, and omentectomy to be performed without laparotomy. Six patients were treated. Only one 10-mm port was required, using an operating laparoscope and an instrument introduced through the working channel of the laparoscope. Adhesiolysis was performed under laparoscopic vision; omentectomy and flushing of blocked catheters were carried out extracorporeally. The catheters were then repositioned to the pelvic cavity under laparoscopic vision. All patients were followed up for 6-10 months. No mechanical problem was noticed. Our one-port laparoscopic technique is a simple and effective method for treating patients who have mechanical problems with their peritoneal dialysis catheters.     

Natural evolution of moderate sleep apnoea syndrome: significant progression over a mean of 17 months

BACKGROUND: Obstructive sleep apnoea (OSA) is associated with increased morbidity and mortality. It has remained unclear whether or not it is progressive. The evolution of OSA was examined in a retrospective case note study of 55 unselected patients of mean (SD) age 55.8 (10) years with mild to moderate disease untreated by interventional methods such as continuous positive airway pressure (CPAP) or surgery. Correlations between clinical and functional variables, upper airway anatomy, and change in disease severity were also investigated. METHODS: Patients underwent full polysomnography on two occasions (T0 and Tx) at a mean interval of 77 (50) weeks (range 17-229). In addition, upper airway imaging with computed tomographic scanning or cephalometry had been performed in 43 patients at T0. Morbidity before, during, and after the study period was assessed by questionnaire, as was smoking history and alcohol and sedative intake. RESULTS: The apnoea hypopnoea index (AHI) for the group as a whole increased from 21.8 (11.5) to 33.4 (21.3) (p = 0.0001). Using a 25% change in AHI to divide patients into worsened, stable, and improved groups showed that, although most of the patients deteriorated, 25 patients improved or remained stable. The change in AHI was not correlated with body mass index which remained stable at 29.7 (5.4) kg/m2 versus 29.7 (5.6) kg/m2. There was a trend for apnoea duration to increase. No patient reported increased alcohol consumption and only one patient reported increased use of sedatives between T0 and Tx. No correlation was found between change in AHI and age, time between recordings, anatomical measurements of the upper airway, respiratory function, oximetry, or arterial blood gas tensions. Total cardiovascular and cerebrovascular morbidity was high: hypertension (26 patients, 46%), cardiac arrhythmia (17 patients, 33%), angina (12 patients, 23%), myocardial infarction (10 patients, 19%), and stroke (10 patients, 19%). Twenty nine patients (52%) were prescribed CPAP after Tx, two of whom went on to have maxillofacial surgery. These 29 treated patients had significantly higher values of AHI at T0 and Tx and greater change in AHI than the untreated patients. CONCLUSIONS: This study shows that mild to moderate OSA has a tendency to worsen in the absence of significant weight gain and that upper airway anatomy and clinical variables do not appear to be useful in predicting progression. It follows that mild to moderate OSA justifies systematic follow up. Deterioration in AHI over a mean of 17 months led to interventional treatment in over 50% of patients in the study.     

Time course of pulmonary artery pressure during sleep in sleep apnoea syndrome: role of recurrent apnoeas

Recent results in animals have suggested that repetition of hypoxaemic stimuli may result in a progressive increase in pulmonary arterial pressure (Ppa). The purpose of the present study was to investigate the effects of recurrent obstructive apnoeas on Ppa. We have, therefore, examined the nocturnal trend of Ppa in seven obstructive sleep apnoea syndrome (OSAS) patients and in five snorers. Mean Ppa was measured before, at the start, at the end and after the selected apnoeas. The analysis was performed for each 1 h period for at least 7 h throughout the night on at least 10 randomly selected apnoeas per hour. In snorers, 100 randomly chosen values were measured during every hour of the night. In the morning after the nocturnal study, the Ppa responses to acute hypoxia and hypercapnia were measured. No Ppa changes throughout the 7 h were found during sleep in snorers [Ppa slope:-0.002+/-0.10 mmHg x h(-1)]. In OSAS patients a small but significant increase in Ppa throughout the night was noted, affecting the values before [Ppa slope: 0.7+/-0.16 mmHg x h(-1)], at the start of apnoea [Ppa slope: 0.530.1 mmHg x h(-1)] as well as at the end [Ppa slope: 0.44+/-0.08 mmHg x h(-1)] and in the postapnoeic period [Ppa slope: 0.55+/-0.1 mmHg x h(-1)]. When we limited the analysis to nonrapid eye movement (NREM) sleep, a trend in progressive Ppa was also present, irrespective of changes in apnoea duration and apnoea desaturation. The Ppa rise during the night was not affected by diurnal Ppa pulmonary vascular response to hypoxia and hypercapnia or indices of sleep apnoea severity. We conclude that in obstructive sleep apnoea, pulmonary artery pressure progressively increases during the night, reflecting the cumulative effects of apnoeas and nocturnal hypoxaemia.     

Effects of psychotherapy in moderately severe COPD: a pilot study

Anxiety is common in the "pink puffer" syndrome associated with chronic obstructive pulmonary disease (COPD). The degree of anxiety correlates well with perceived dyspnoea. This pilot study examines the effect of group psychotherapy on anxiety, exercise tolerance, dyspnoea and quality of life. Ten patients with moderately severe, stable COPD (mean forced expiratory volume in one second (FEV1)-1.15 L) had six 90 min sessions of cognitive and behavioural psychotherapy at weekly intervals. Patients completed the Hospital Anxiety and Depression Scale (HADS), Medical Research Council Questionnaire (MRCQ) and St George's Respiratory Questionnaires (SGRQ), 1 week before and after therapy. FEV1, forced vital capacity (FVC), slow vital capacity (SVC), blood gas tensions and 6 min walking distance (6MWD) were measured. Eight control patients attended weekly for lung function and 6MWD for 6 weeks, but had no psychotherapy. Mean baseline HADS score was significantly higher in the psychotherapy group (12) than in controls (7), but otherwise there were no differences in lung function, blood gas tensions, 6MWD, or the other questionnaire scores between groups. After treatment, the physiological and psychological parameters where unchanged in both groups with the exception of the mean 6MWD, which had improved in the psychotherapy group only, from 351 to 423 m (p<0.001), an increase of 24%. Three months after treatment, the 6MWD was still 16% above the baseline value (p=0.02). In conclusion, six sessions of cognitive and behavioural psychotherapy produced a sustained improvement in exercise tolerance in a group of 10 anxious patients with severe chronic obstructive pulmonary disease, without any change in anxiety scores on the Hospital Anxiety and Depression Scale. Further studies of more prolonged, intensive psychotherapy would establish whether better symptom and quality of life scores accompany more dramatic increases in exercise tolerance in "pink puffers".     

Goitre: a cause of obstructive sleep apnoea in euthyroid patients

While hypothyroidism is considered to predispose to obstructive sleep apnoea (OSA), the presence of a goitre itself is not a recognized cause of OSA. We present the cases of two euthyroid patients with large goitres and clinical evidence of OSA, whose OSA symptoms significantly improved following partial thyroidectomy. This finding suggests that the goitre contributed to their symptoms.     

Histologic evaluation of the LaminOss osteocompressive dental screw: a pilot study

This animal study compared the response of canine mandibular bone using the orthopedic principle of osteocompression by the function of an immediately loaded dental implant vs an unloaded dental implant of the same design and size. Two dogs were partially edentulated in the mandible. A total of 8 osteocompressive screw implants, 2 per quadrant were placed and evaluated histomorphometrically after 3 days in 1 dog and after 3 months in the second dog. The second dog had a two-unit fixed bridge placed immediately postsurgically in occlusal function on the right side; on the left side, the implants were splinted out of occlusion as a control. Histologically, no bone necrosis was observed at the implant interface by any of the 8 implants for either period as a direct result of the 4-mm-diameter by 13-mm-length implant design. Clinical parameters did not differ among the implants; however, at 3 months, the immediately loaded implants demonstrated more than twice the amount of bone density at their surfaces compared to the unloaded implants of the same design. Future human clinical research would be necessary to provide a meaningful statistical analysis to validate the importance of this implant design and the function of osteocompression.     

Nocturnal evolution of respiratory effort in obstructive sleep apnoea syndrome: influence on arousal threshold

It has been recently described that the overnight increase in maximal end-apnoeic oesophageal pressure (P(oes,max)), considered as an index of the arousal threshold to occlusion, mostly contributes to apnoea lengthening during the night. However, the rise in apnoea duration could also be caused by changes in hypoxaemia, chemosensitivity and upper airway resistance. To better define the relative contributions of each of these factors, we examined the recordings of nine patients. Before apnoea, the mean pulmonary resistance at peak inspiratory flow (RPIF) was computed. During apnoea, all swings in oesophageal pressure (P(oes)) were measured to define the P(oes,max), the increase from the minimum to the maximum (deltaP(oes)), the rate of increase in P(oes) (RP(oes)) and the P(oes) at the first occluded breath (P(oes,1)). A gradual and significant increase in apnoea duration (p=0.02), P(oes,max) (p=0.02) and deltaP(oes) (p=0.006) was present across the night without any changes in oxygen saturation, RPIF, and P(oes,1). The slope of increase in P(oes,max), apnoea duration and deltaP(oes) was correlated with the apnoea/hypopnoea index. We conclude that in obstructive sleep apnoea, the nocturnal rise in apnoea duration is attributable more to an increase in the arousal threshold related to apnoea recurrence than to changes in chemosensitivity and upper airway resistance.