The Kushida Index as a screening tool for obstructive sleep apnoea-hypopnoea syndrome.

OBJECTIVES: To test the validity of the Kushida Index for screening for sleep apnoea in a West of Scotland adult population. METHODS: Specific intra-oral measurements and respiratory polysomnography were carried out on 71 patients in this prospective study. The intra-oral measurements were applied to the Kushida formula to obtain a value for the Kushida Index. This value was compared to the diagnosis obtained using polysomnography in the conventional manner. RESULTS: The sensitivity of the Kushida Index in this present study was 68% (95% CI 50-81) and the specificity was 71% (95% CI 52-84). The positive predictive value was 71% and the negative predictive value was 67%. The Mallampati score, Epworth sleepiness score and enlargement of the tongue, soft palate or tonsils were not statistically significantly related to a diagnosis of sleep apnoea (p >0.05). CONCLUSION: With the limited sensitivity and specificity of the Kushida Index demonstrated in this study, this test cannot be recommended as a screening tool for sleep apnoea in a West of Scotland population.

The attitudes of general dental practitioners and medical specialists to the provision of intra-oral appliances for the management of snoring and sleep apnoea.

AIM: To determine the attitudes and awareness of dental and medical practitioners in Scotland to the provision of oral appliances for the management of snoring and sleep apnoea. SETTING: The questionnaire was completed by general dental practitioners randomly selected from across Scotland and by doctors specialising in sleep medicine within Scotland. METHOD: A questionnaire was devised and sent to 17 specialists in sleep medicine and 210 general dental practitioners, community dental service practitioners and hospital-based dental practitioners. A reply-paid envelope was included with each questionnaire. RESULTS: There were 14 replies (82%) from specialists and 105 (50%) from dentists. All the specialists felt that dentists had a role in the management of these patients. Of the replies from dentists, 60 (57%) stated that they provided appliances but their screening for sleep apnoea and discussion of the side-effects of appliances varied widely. Seventy-eight dentists (74%) expressed an interest in attending a course on the management of sleep apnoea and snoring. CONCLUSIONS: The current practice of specialists and dentists in the management of obstructive sleep apnoea and socially disruptive snoring with oral appliances in Scotland is varied. Many dentists expressed a wish for further training in this area.

Assessment of sleep studies in myotonic dystrophy.

Myotonic dystrophy (MD) is the commonest adult muscular dystrophy and is associated with respiratory muscle weakness. The role of screening sleep studies is unclear in MD. We prospectively evaluated polysomnography/overnight oximetry in a group of MD patients and related this to the daytime respiratory function in an attempt to evaluate the usefulness of screening sleep studies. Twenty-five patients with type I MD [15 males; mean age (SD) 40.0 (10.9) years] who had at least one symptom suggestive of nocturnal hypoventilation were included in the study. We performed spirometry, maximal inspiratory and expiratory mouth pressures, sniff nasal inspiratory pressure, arterial blood gases and polysomnography or overnight oximetry. Excessive tiredness and sleepiness were the most common presenting symptoms. Prevalence of sleep related breathing disorder (SRBD) was 36%. FVC was found to be normal in 33% of subjects with significant SRBD. Mouth pressures were reduced more than FVC, even in patients with normal overnight oxygen saturation. Of all the daytime measures, FVC correlated best with arterial carbon dioxide tension (r = -0.7). Sleep studies were useful to identify a small group of myotonic dystrophy patients (12%, three out of 25 in our series) with SRBD that would have been missed with routine daytime assessments. Targeted sleep monitoring in patients who are older, with multiple symptoms suggestive of SRBD, especially if they are overweight seems to be the best way to utilize the existing resources. Home unattended oximetry was well tolerated and offers a practical screening tool in this challenging patient group where excess daytime sleepiness is often due to causes other than SRBD.

Long-term continuous positive airway pressure (CPAP) outcomes from a sleep service using limited sleep studies and daycase CPAP titration in the management of obstructive sleep apnoea/hypopnoea syndrome.

BACKGROUND: Detailed polysomnography (PSG) and overnight continuous positive airway pressure (CPAP) titration as the basis for investigation and treatment of obstructive sleep apnoea/hypopnoea syndrome (OSAHS) incurs high costs from inpatient stays and technician attendance, even when split night studies are employed. Responding to rapidly increasing demand, from 1996 the sleep service at Glasgow Royal Infirmary adopted limited sleep studies and daycase CPAP titration as first line management. Here we describe the outcomes of this service between 1996 and 1999. METHODS: Data were collected from prospective records made at follow up by sleep technicians and by casenote review. RESULTS: Results were available for 158 subjects (97.5%) of 162 commenced on CPAP during this period. One hundred and forty-eight (91%) were diagnosed by limited sleep studies and 80 (50%) were diagnosed at home. The median follow up was 23 months (interquartile range (IQR), 13-35). Median use of CPAP in those continuing therapy was 5.3 hours/night (IQR, 3.1 to 6.5) and 77% were still using CPAP at three years. Only initial low CPAP compliance (< 2 hours/night) significantly predicted early CPAP cessation. In those still on CPAP in 1999, the mean drop in Epworth Sleepiness Scale score was 4.6 points (95% confidence intervals, 3.2 to 6.0). CONCLUSION: These data from the CPAP population at Glasgow Royal Infirmary provide information on longterm outcomes using a diagnostic protocol based on limited sleep studies and daycase CPAP titration.

Snoring, sleep apnoea and the role of dental appliances.

This article describes the problems of snoring and obstructive sleep apnoea, together with an outline of treatment options. The Glasgow approach, whereby patients are investigated at a sleep clinic and a custom-made mandibular advancement device is made in semi-soft material, is also described. We have demonstrated the acceptability and effectiveness of a simple appliance in patients with varying dental states, some with simple snoring and some with mild to moderate sleep apnoea. Our experience relates to around 260 patients, extending over a period of 4 years with good success. The simple intraoral device is recommended as a first line of approach for patients with problem snoring.

Use of transcutaneous oxygen and carbon dioxide tensions for assessing indices of gas exchange during exercise testing.

The slow response characteristics of the combined transcutaneous electrode have been viewed as a major disadvantage when compared with other types of non-invasive assessment of gas exchange during exercise testing. We have previously shown that by using the highest recommended temperature of 45 degrees C to reduce response times, and combining this with an exercise protocol of gradual work load increments, that this allows changes in arterial blood gases to be closely followed by transcutaneous values. In the present study we have validated the use of a transcutaneous electrode for estimation of alveolar-arterial oxygen gradient (AaO2) and dead space to tidal volume ratio (V(D)/V(T)) during exercise, against values calculated from direct arterial blood gas analysis. One hundred measurements were made in 20 patients with various cardiopulmonary disorders who underwent exercise testing. Exercise testing was performed by bicycle ergometry with a specific protocol involving gradual work load increments at 2 min intervals. Transcutaneous gas tensions were measured by a heated combined O2 and CO2 electrode. Arterial blood was sampled at the midpoint of each stage of exercise and transcutaneous tensions noted at the end of each stage. The mean difference of the AaO2 gradient calculated from blood gas tensions obtained by the two methods was 0.14 kPa. The limits of agreement were -0.26 and 0.63 kPa. The same values for V(D)/V(T) calculated from gas tensions measured by the two methods were: mean difference 0001; limits of agreement -0.0242 and 0.0252. For both these parameters there was an even scatter around the mean value on Bland and Altman analysis. The findings of this study suggest that estimation of parameters of gas exchange using transcutaneous values during exercise testing is reliable, provided the electrode is heated to a slightly higher temperature than usual and the work load increments are gradual, allowing for the latency in the response time of the system. This system allows the assessment of the contribution of ventilation/perfusion inequality to breathlessness on exertion in patients, provided an initial arterial or ear lobe capillary sample is obtained for calibration purposes. This technique is particularly valuable in patients undergoing repeat exercise tests as it circumvents the need for arterial cannulation.

An investigation of factors limiting aerobic capacity in patients with ankylosing spondylitis.

Ankylosing spondylitis (AS) has been shown to produce exercise limitation and breathlessness. The purpose of this study was to investigate factors which may be responsible for limiting aerobic capacity in patients with AS. Twenty patients with no other cardio-respiratory disease performed integrative cardiopulmonary exercise testing (CPET). The results were compared to 20 age and gender matched healthy controls. Variables that might influence exercise tolerance, including pulmonary function tests (body plethysmography), respiratory muscle strength (MIP, MEP) and endurance (Tlim), AS severity assessment including chest expansion (CE), thoracolumber movement (TL), wall tragus distance and peripheral muscle strength assessed by maximum voluntary contraction of the knee extensors (Qds), hand grip strength and lean body mass (LBM), were measured in the patients with AS and used as explanatory variables against the peak VO2 achieved during CPET. As subjects achieved a lower peak VO2 than controls (25.2 +/- 1.4 vs. 33.1 +/- 1.6 ml kg-1min-1, mean +/- SEM, P = 0.001). When compared with controls, ventilatory response (VE/VCO2) in AS was elevated (P = 0.01); however gas exchange indices, transcutaneous blood gases and breathing reserve were similar to controls. AS subjects developed a higher HR/VO2 response (P < 0.01) on exertion but without associated abnormalities in ECG, blood pressure response or anaerobic threshold. The AS group experienced a greater degree of leg fatigue (P < 0.01) than controls at peak exercise. Although the breathlessness scores (BS) were comparable to controls at peak exercise, the slopes of the relationship between BS and work rate (WR) [AS 0.054 (0.1), Controls 0.043 (0.06); P < 0.05] and BS and % predicted oxygen uptake [AS 0.084 (0.18), Controls 0.045 (0.06); P < 0.01] were steeper in the AS subjects. There was weak association between peak VO2 and vital capacity (r2% 12.0), MIP (11.8) but no association between Tlim, CE, Wall tragus distance or TL movement. The strongest association with aerobic capacity was between measurements of peripheral muscle strength (Qds; r = 0.75; hand grip; r = 0.47) accounting for 53% (P < 0.001) and 23.5% (P < 0.01) of the total variance in peak VO2, respectively. The addition of LBM to Qds in the regression model significantly improved the explained variance to 78.3% (P < 0.001). This study shows that peripheral muscle function is the most important determinant of exercise intolerance in AS patients suggesting that deconditioning is the main factor in the production of the reduced aerobic capacity.

Pilot study of a semi-flexible intra-oral appliance for the control of snoring.

OBJECTIVE: To determine the effectiveness and acceptability of an intra-oral appliance in the reduction of snoring, with construction and fitting as a 1-visit process. DESIGN AND SETTING: This was a prospective study. Patients were attending a hospital sleep breathing disorders clinic and appliances were made at a dental hospital. This work was carried out in the UK during 1996 and 1997. SUBJECTS AND METHODS: Patients were selected from those referred to a sleep breathing disorders clinic with socially disruptive snoring. MAIN OUTCOME MEASURES: Patients were assessed by means of limited sleep studies and by questionnaires before and after fitting of the appliances. The sleep studies consisted of monitoring respiratory variables (principally oronasal airflow and nocturnal oxygen saturation). A respiratory disturbance index was assigned. Questionnaires were completed by both patients and sleep partners, with many of the responses being marked on visual analogue scales. RESULTS: 16 male patients, mean age 49 years, were included in the trial. 14 were able to wear the appliance and their level of snoring, as assessed by their sleep partners, reduced from a mean of 8.8 out of 10 to 4.2 out of 10 (P = 0.0003, paired t-test). CONCLUSION: It is concluded that the semi-flexible intra-oral appliance is effective in the control of snoring.

Systematic analysis of snoring in women.

Nineteen percent of women are habitual snorers, yet most snoring studies report only on male snorers. The aim of this study was to identify the factors responsible for habitual snoring in women. Twenty-four snorers and 16 controls were studied prospectively in a special snoring clinic. Snorers were shorter (p = .005) and heavier (p = .001), and with greater body mass index (BMI: p < .001), collar size (p = .002), and submental skinfold thickness (p = .001) than controls. The area of the posterior pharyngeal wall visible on oral examination was smaller in snorers (p = .005). Acoustic rhinometry areas and volumes were similar in the two groups. Nasal flow-volume loops showed reduced expiratory (p = .01) and inspiratory (p = .07) flow in snorers. Inspiratory flow correlated inversely with nasal symptoms (p < .05). The factors that best predict habitual snoring in women are a high BMI, a high nasal symptom score, and heavy weight. Of these, BMI is the most powerful.

An evaluation of integrated cardiopulmonary exercise testing in a pulmonary function laboratory.

Clinical exercise testing has been used mainly to assess the cardiac response to exercise. Integrative cardiopulmonary exercise tests (CPET) involving the measurement of the ventilatory, circulatory and metabolic response to exercise has largely been a research tool. We analysed the results of one hundred tests randomly chosen from a total of 472 exercise tests performed between January 1992 and June 1993 as clinical investigation in a pulmonary function laboratory. CPET was used (a) to identify the cause of effort limitation in patients where more than one illness could be relevant (26); (b) to obtain an objective measure of the exercise capacity of patients with respiratory or cardiac disease (31); (c) as monitor of response to treatment (11) and (d) in the investigation of unexplained dyspnoea (32). In 94 of the 100 cases CPET was able to provide an answer to the specific clinical question posed. In patients with unexplained dyspnoea (CPET identified a group who exhibit an inappropriate hyperventilatory response to exercise with no supportive evidence of cardiopulmonary disease. In a small minority of cases CPET gave non-specific results. We conclude that CPET is a useful investigation in the management of patients with cardiopulmonary disease and complements the various other investigations offered by a pulmonary function laboratory.

Breathlessness in microvascular angina.

In patients with microvascular angina (MA), there is some evidence from studies of plethysmography, that there are widespread microvascular abnormalities. In addition to exertional chest pain, all these patients complain of breathlessness, with no evidence of airways obstruction or resting left ventricular dysfunction. Progressive exercise testing was performed in 12 age and sex matched controls and 12 patients (three males), in whom the diagnosis of MA was established on the basis of exertional chest pain, abnormal thallium scans, and an attenuated myocardial flow response to a vasodilator challenge, with angiographically entirely normal epicardial vessels. Symptom limited exercise was performed with on line ventilation and expired gas analysis, measuring minute ventilation, oxygen consumption and carbon dioxide production and arterial blood gas values using a transcutaneous system. Anaerobic threshold was calculated by curve fitting a plot of oxygen consumption against carbon dioxide production. Compared to controls (49.7 +/- 7.3 SD% predicted maximum VO2) in patients with MA, the anaerobic threshold was reduced (41.6 +/- 5.82; P < 0.02) although still within accepted normal limits. Maximal (symptom limited) oxygen consumption, as a percentage of predicted, was reduced 60.73 +/- 16.51 compared to 87.21 +/- 5.2 (P < 0.003). The ventilatory response (VE/VCO2 l l-1 CO2 output) was significantly increased in the MA patients compared to controls (35.9 +/- 8.01 and 27.5 +/- 3.08, respectively; P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting resting energy expenditure in patients with musculoskeletal deformities.

UNLABELLED: The aim of this study was to assess the validity of the commonly used equations (Harris-Benedict (HB), Schofield (S) and equations based on midarm circumference (MAC) and midarm muscle circumference (MAMC) in predicting resting energy expenditure (REE) in a population of patients with musculoskeletal deformities. 20 kyphoscoliotic patients (15 female (F); 5 male (M); mean age 59.6 years) and 10 controls (7 F; 3M; 59.8 years) were studied. REE measured by indirect calorimetry (IC) with a ventilated canopy system (Deltatrac metabolic monitor) was not significantly different between patients and controls (Mean (SD) REE (MJ/24 h): PATIENTS: 5.48 (1.1); controls: 5.28(0.8)). In patients with deformities the Schofield equation gave values which were closest to measured REE (mean difference and limits of agreement IC vs S: 0.098 MJ/24 h; -0.822 and 1.018). The Harris-Benedict equation using height (Ht) and armspan (AS) in lieu of height also gave acceptable results (IC vs HB (Ht): 0.34; -0.638 and 1.318; IC vs HB (AS): 0.255; -0.683 and 1.253). Equations based on MAC and MAMC compared poorly (IC vs MAC equation: 0.398; -1.530 and 2.326; IC vs MAMC equation 0.687; -0.911 and 2.285). On regression analysis the equation REE = 0.295 (MAMC) + 0.0483 (AS) -0.0324 (age) -6.25 predicted REE best in the patient population (r(2) = 0.861).

Resting energy expenditure and nutritional state of patients with increased oxygen cost of breathing due to emphysema, scoliosis and thoracoplasty.

BACKGROUND: Weight loss is a well recognised feature of patients with emphysematous chronic obstructive pulmonary disease (COPD). It has been suggested that this weight loss could be due to a hypermetabolic state resulting from the increased oxygen cost of breathing (OCB). To clarify the relation between resting energy expenditure (REE), nutritional state, and OCB these indices were measured in patients with respiratory impairment and an increased OCB due to COPD, scoliosis, and thoracoplasty. METHODS: Eighteen patients (six COPD, six scoliosis, six thoracoplasty) of mean (SD) age 59.9 (8.6) years (8M, 10F) and six controls (45.5 (9.9) years; 2M, 4F) were studied. OCB was estimated by the addition of dead space to the breathing circuit and REE was measured by indirect calorimetry using a ventilated canopy system. Height, arm span, weight, triceps skin fold thickness (TSF), mid-arm muscle circumference (MAMC), forced expiratory volume in one second (FEV1), and vital capacity (VC) were measured in all study subjects. RESULTS: OCB was elevated in all patient groups (mean 7.0 ml/l) compared with controls (1.9 ml/l). All patients with COPD, four with scoliosis, three with thoracoplasty, and none of the controls were < 90% ideal body weight. Mean (SD) measured REE as % predicted (Harris-Benedict equation) was 103.8 (7.6) in patients with COPD, 105.5 (10.9) in those with scoliosis, 106.3 (6.9) in the thoracoplasty patients, and 103.3 (3.4) in controls. One patient with COPD, two with scoliosis, two with thoracoplasty, but no controls were hypermetabolic (REE > 110% predicted). In all groups there was a negative relation between OCB and lung function (OCB v FEV1 r = -0.83 in COPD, -0.62 in scoliosis, -0.67 in thoracoplasty, and -0.76 in controls). There was no correlation between REE and OCB or MAMC. CONCLUSIONS: In patients with respiratory disease OCB (augmented ventilation) is related to lung function but not to REE. This is evidence against the hypothesis that hypermetabolism due to increased oxygen cost of breathing at rest is the sole or major cause of malnutrition in patients with lung disease.

Diaphragmatic paralysis in motor neurone disease: use of non-invasive investigative and therapeutic techniques.

Two cases of bilateral diaphragmatic weakness are described in which the condition was the presenting feature of motor neurone disease. Inspiratory muscle strength was assessed by a non-invasive technique involving measurements of pressures generated within the mouth. One patient with severe inspiratory muscle weakness is being treated with domiciliary nasal ventilation and has returned to a good-quality life. The other patient with less severe weakness has thus far required no ventilatory support.

An out-patient nutritional supplementation programme in COPD patients.

Studies that have assessed the role of nutritional supplementation in patients with emphysematous chronic obstructive pulmonary disease (COPD) have shown conflicting results. Improved respiratory muscle strength and exercise capacity have been demonstrated following intensive and costly nutritional support programmes under controlled conditions. We have evaluated a simple programme of out-patient nutritional support in a clinical setting. Twelve malnourished COPD patients (9 male and 3 female; mean age 66 yrs; < 90% ideal body weight) were studied. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), estimation of maximal oxygen uptake (VO2max) during exercise, respiratory muscle strength (PImax and PEmax), and measurement of body weight, height, triceps skinfold thickness, and mid-arm muscle circumference were performed before and after a 4 month period of out-patient nutritional support. Patients were advised by a dietician on increasing their daily caloric intake by a minimum of 50% above estimated daily energy expenditure. Three patients withdrew from the study. The mean increase in body weight in the nine remaining patients after 4 months of supplementation was 0.3 kg. There was no significant improvement in the anthropometric measures, lung function, respiratory muscle strength or VO2max for the group as a whole. Three patients who gained more than 1 kg weight were from a higher socioeconomic background compared with those who failed to do so. We conclude that achieving weight gain and improving lung function by means of simple out-patient nutritional programmes in a clinical setting is difficult.

Use of a combined oxygen and carbon dioxide transcutaneous electrode in the estimation of gas exchange during exercise.

BACKGROUND: Accurate and reliable measurement of gas exchange during exercise has traditionally involved arterial cannulation. Non-invasive devices to estimate arterial oxygen (O2) and carbon dioxide (CO2) tensions are now available. A method has been devised and evaluated for measuring gas exchange during exercise with a combined transcutaneous O2 and CO2 electrode. METHODS: Symptom limited exercise tests were carried out in 24 patients reporting effort intolerance and breathlessness. Exercise testing was performed by bicycle ergometry with a specifically designed protocol involving gradual two minute workload increments. Arterial O2 and CO2 tensions were measured at rest and during exercise by direct blood sampling from an indwelling arterial cannula and a combined transcutaneous electrode heated to 45 degrees C. The transcutaneous system was calibrated against values obtained by direct arterial sampling before each test. RESULTS: In all tests the trend of gas exchange measured by the transcutaneous system was true to the trend measured from direct arterial sampling. In the 140 measurements the mean difference between the O2 tensions estimated by direct sampling and the transcutaneous method was 0.08 kPa (0.62 mm Hg, limits of agreement 4.42 and -3.38 mm Hg). The mean difference between the methods for CO2 was 0.02 kPa (0.22 mm Hg, limits of agreement 2.20 and -1.70 mm Hg). There was no morbidity associated with the use of the transcutaneous electrode heated to 45 degrees C. CONCLUSIONS: A combined transcutaneous O2 and CO2 electrode heated to 45 degrees C can be used to provide a reliable estimate of gas exchange during gradual incremental exercise in adults.

Intravenous pamidronate in the treatment of osteoporosis associated with corticosteroid dependent lung disease: an open pilot study.

BACKGROUND: Bisphosphonates have been shown to be effective agents in the treatment of postmenopausal osteoporosis. Because corticosteroid associated osteoporosis is often associated with increased bone turnover, the effect of intermittent intravenous infusions of pamidronate on this condition has been investigated. METHODS: Seventeen patients (five male) with chronic corticosteroid dependent lung disease (15 asthma, two sarcoidosis) were treated with infusions of 30 mg pamidronate once every three months for one year. These patients had been taking an average of 14 (range 7.5-40) mg prednisolone a day for an average of 14 (range 3-30) years. Bone density measurements, by dual energy x ray absorptiometry, and radiography of the dorsolumbar spine were carried out before and one year after treatment. Bone formation was assessed by measurement of serum alkaline phosphatase and bone resorption by measurement of the fasting urinary hydroxyproline: creatinine ratio at the same time as densitometry and radiography were performed. RESULTS: Pretreatment density of L2-4 and the neck of the femur was significantly lower in these patients compared with a cohort of 100 age and sex matched controls (L2-4 (mean (SEM)): 0.906 (0.050) g/cm2 v 1.142 (0.016) g/cm2; neck of femur: 0.793 (0.030) g/cm2 v 0.936 (0.013)) g/cm2. After treatment there was a significant fall in serum alkaline phosphatase activity from (mean (SEM)) 220 (16) U/1 to 174 (9) U/1 (normal 80-280 U/1) and in the fasting urinary hydroxyproline:creatinine ratio from (mean (SEM) 0.040 (0.006) to 0.024 (0.003) (normal < 0.033). A significant rise was noted in L2-4 density to 0.927 (0.047) g/cm2; mean rise of 3.4%). No change was noted in density of the neck of the femur. CONCLUSIONS: Intermittent infusions of intravenous pamidronate would seem to be effective in both reducing turnover of bone and increasing bone density in corticosteroid induced osteoporosis associated with chronic lung disease. Longer term controlled studies are indicated.

Treatment of pulmonary aspergilloma with itraconazole.

In a 12 month open study of itraconazole in pulmonary aspergilloma nine patients received oral itraconazole 200 mg daily for six months followed by further itraconazole or observation for a further six months. There was no change in the serum IgG specific for Aspergillus fumigatus (mean (SE) change -4% (10%)) or symptoms of chronic cough and haemoptysis. In two of the three patients who continued treatment beyond six months symptoms and radiographic appearances improved and a temporary reduction in A fumigatus specific IgG occurred in one patient. Further experience of the effects of longer treatment are needed before oral itraconazole can be recommended for aspergilloma.