A prospective observational study to evaluate the effect of social and personality factors on continuous positive airway pressure (CPAP) compliance in obstructive sleep apnoea syndrome.

BACKGROUND: Compliance with CPAP treatment for OSAS is not reliably predicted by the severity of symptoms or physiological variables. We examined a range of factors which could be measured before CPAP initiation to look for predictors of compliance. METHODS: This was a prospective cohort-study of CPAP treatment for OSAS, recording; socio-economic status, education, type D personality and clinician's prediction of compliance. RESULTS: We recruited 265 subjects, of whom 221 were still using CPAP at 6 months; median age 53 years, M: F, 3.4:1, ESS 15 and pre-treatment ODI 21/h. Median compliance at 6 months was 5.6 (3.4- 7.1) hours/night with 73.3% of subjects using CPAP ≥4 h/night. No association was found between compliance and different socio-economic classes for people in work, type D personality, education level, sex, age, baseline ESS or ODI. The clinician's initial impression could separate groups of good and poor compliers but had little predictive value for individual patients. Compared to subjects who were working, those who were long term unemployed had a lower CPAP usage and were more likely to use CPAP < 4 h a night (OR 4.6; p value 0.011). A high Beck Depression Index and self-reported anxiety also predicted poor compliance. CONCLUSIONS: In our practice there is no significant association between CPAP compliance with socio-economic status, education or personality type. Long term unemployed or depressed individuals may need more intensive support to gain the optimal benefit from CPAP.

Pre-flight assessment in patients with obesity hypoventilation syndrome.

BACKGROUND AND OBJECTIVE: Reduced atmospheric pressure during air travel can cause significant hypoxaemia in some patients with respiratory disease. Our aims were to investigate the degree of hypoxaemia in patients with obesity hypoventilation syndrome (OHS) during hypoxic challenge test (HCT), and to identify any predictors of a positive HCT. METHODS: Thirteen patients underwent assessment, including HCT, lung function and incremental shuttle walk test. All had OHS well controlled with long-term nocturnal non-invasive ventilation (NIV). Patients with chronic obstructive pulmonary disease were excluded. A positive HCT was defined according to the British Thoracic Society (BTS) recommendation as arterial oxygen tension (PaO2) <6.6 kPa and/or oxygen saturation <85%. RESULTS: Mean age was 57 (± 11) years. Mean body mass index was 51.7 (± 12) kg/m(2) . Mean baseline PaO2 and arterial carbon dioxide tension (PaCO2) were 10.2 (9.5-11.3) kPa and 5.2 (3.7-6.8) kPa, respectively. Seven patients (54%) had a positive HCT. The correlation between baseline PaO2 and PaO2 at the end of the HCT was not statistically significant (r = 0.433, P = 0.184). A negative correlation was observed between baseline PaCO2 and PaO2 at the end of the HCT (r = -0.793, P = 0.004). A positive correlation was observed between the distance walked and the PaO2 at the end of the HCT (r = 0.608, P = 0.047). CONCLUSIONS: OHS is a risk factor for severe hypoxaemia during air travel even if the ventilatory failure is well controlled. An HCT before air travel is advisable in all OHS patients. Those with positive HCT may use NIV or have oxygen on-board as per BTS recommendation.

A randomised crossover trial comparing volume assured and pressure preset noninvasive ventilation in stable hypercapnic COPD.

Recent randomised controlled trials suggest non-invasive ventilation may offer benefit in the long-term management of ventilatory failure in stable COPD. The best mode of ventilation is unknown and newer volume assured modes may offer advantages by optimising ventilation overnight when treatment is delivered. This study compares volume assured with pressure preset non-invasive ventilation. Randomised crossover trial including twenty five subjects previously established on long-term non-invasive ventilation to manage COPD with chronic ventilatory failure. Two 8-week treatment periods of volume assured and pressure preset non-invasive ventilation. The primary outcomes were daytime arterial blood gas tensions and mean nocturnal oxygen saturation. Secondary outcomes included lung function, exercise capacity, mean nocturnal transcutaneous carbon dioxide, health status and compliance. No significant differences were seen in primary or secondary outcomes following 8 weeks of treatment when comparing volume assured and pressure preset ventilation. Primary outcomes assessed: mean (standard deviation) PaO(2) 7.8 (1.2) vs 8.1(1) kPa, PaCO(2) 6.7 (1.1) vs 6.3 (1.2) kPa and mean nocturnal oxygenation 90 (4) vs 91 (3)% volume assured versus pressure preset, respectively. Volume assured and pressure preset non-invasive ventilation appear equally effective in the long-term management of ventilatory failure associated with stable COPD.

Abdominal tuberculosis in Bradford, UK: 1992-2002.

INTRODUCTION: Bradford, in West Yorkshire, United Kingdom, has a population of 486 340 of which 17.3% originate from South Asia. We describe our experience of abdominal tuberculosis over a 10 year period. METHODS: Fifty-nine cases of abdominal tuberculosis were identified between 1992 and 2002 from the Tuberculosis Registry, Bradford hospitals. Fifty case records were available for retrospective review. RESULTS: Median age of the patients was 38 years (range, 14-81) and 35 (59.3%) were females. Fifty-four (91.5%) patients were of South Asian origin, four (6.8%) were Caucasians and one patient was an Arab. The mean standardized incidence of abdominal tuberculosis in the South Asian population during the study period was 9.32 cases/10(5)/year whereas in the local white population it was 0.1/10(5)/year (relative risk=93). Fever (90%), abdominal pain (88%) and weight loss (82%) were the commonest presenting features. Ileocaecal region in 20 (40%) patients and tubercular peritonitis in 16 (32%) cases were the common sites involved. Active pulmonary tuberculosis was present in 18 (36%) patients. Diagnosis of tuberculosis was confirmed by isolating acid-fast bacilli or by demonstrating caseating granulomas on biopsy in 36 (72%) cases. Acid-fast bacilli isolated in all the 29 (58%) cases were Mycobacterium tuberculosis and were sensitive to all standard anti-tubercular drugs except one patient who was resistant to isoniazid. CONCLUSION: Abdominal tuberculosis remains a common problem in a multicultural community in the United Kingdom with a varied presentation. High index of suspicion is required for early diagnosis. Most of the patients respond very well to standard anti-tubercular therapy and surgery is required only in a minority of cases. Drug resistant abdominal tuberculosis has not been a problem in this series.

The impact of changing people with sleep apnea using CPAP less than 4 h per night to a Bi-level device.

Pressure intolerance is a reason for poor acceptance and subsequent compliance in some patients starting treatment with continuous positive airway pressure (CPAP). In unselected populations initiating CPAP; different types of pressure generating device have not been found to improve compliance. We hypothesized that using Bi-level PAP for patients who reported pressure related discomfort as a cause for poor compliance with CPAP might increase their hours of treatment use. Patients using CPAP <4 h/night with symptoms to suggest pressure intolerance were randomized to receive either a Bi-level PAP device or a new CPAP for 4 weeks. Following a washout period of 2 weeks, they were crossed over to the other device for 4 weeks. Twenty eight volunteers completed the protocol. Compared to the baseline (mean 1.49 h per night), improvement in compliance was noticed when changed to a new CPAP (2.23 h, p = 0.006) or Bi-level PAP (2.73 h, p < 0.001). The trend suggesting superior compliance with a Bi-level PAP device compared to new CPAP was not significant (p = 0.059) and there were no differences in subjective or objective measures of sleepiness. The results of this study suggest that routine intervention with Bi-level PAP in this group of sub-optimally compliant individuals was not very effective in improving PAP usage. There is however a subgroup of patients who complains of difficulty with exhalation; where favorable trends towards improved compliance were observed on Bi-level PAP.

Hypoxic challenge assessment in individuals with obstructive sleep apnea.

BACKGROUND: The degree of arterial hypoxemia during air travel in individuals with obstructive sleep apnea (OSA) is not known. The Aerospace Medical Association considers a ground level arterial oxygen tension (PaO2) above 9.3 kPa as safe before air travel. METHODS: Fifteen subjects with untreated OSA (mean apnea-hypopnea index [AHI] 43/h) and 14 with treated OSA (mean AHI on CPAP 1.9/h) completed an assessment including hypoxic challenge test (HCT). The groups had similar mean age, mean BMI and pre-treatment OSA severity. RESULTS: Four subjects, all in the untreated group and with resting PaO2 >9.3 kPa and oxygen saturation (SpO2) >95%, had a positive HCT (PaO2 <6.6 kPa and/or SpO2 <85%). The PaO2 at the end of the HCT was significantly correlated with the minimum overnight SpO2 (r=.754, p=.002) but not with the daytime PaO2 and SpO2. Using a cut off value of 65%, the minimum overnight SpO2 had positive and negative predictive values of 57% and 100% respectively. CONCLUSIONS: OSA can be an additional risk factor for developing significant arterial hypoxemia during HCT. Baseline PaO2 and SpO2 did not predict arterial hypoxemia during the HCT. Minimum overnight SpO2 <65% may be used as a cut off to advise further assessment. Effective treatment of OSA seems to be the best option before air travel.

Can a single cephalometric measurement predict obstructive sleep apnea severity?

STUDY OBJECTIVES: To look for an association between the vertical position of the hyoid, as measured by the sella-hyoid (S-H) distance and the severity of obstructive sleep apnea (OSA). A previously published study on this subject showed a significant correlation between S-H distances more than 120 mm and severe OSA. DESIGN AND SETTING: A retrospective study of patients who were treated with a mandibular advancement splint (MAS) for sleep disordered breathing during June 2000 to May 2005 at the orthodontic department of Colchester University Hospital. PATIENTS AND PARTICIPANTS: One hundred and six consecutive patients who were treated with MAS during the period. MEASUREMENTS AND RESULTS: Lateral cephalograms were taken and traced prior to the provision of MAS therapy, and the distance S-H was measured. The mean S-H distance was 125.5 mm (103-148 mm) with a median of 126 mm. Four out of 8 patients (50%) with severe OSA had a S-H distance more than 120 mm, as did 38 out of 50 (76%) with mild to moderate OSA (AHI 5-30), and 17 out of 22 patients (77.27%) with an AHI of 0 to 4. No significant correlations between the S-H distance and the severity of OSA were found (Pearson correlation coefficient -0.034 and 95% confidence interval: -0.25, 0.18). CONCLUSION: There was no correlation between patients' OSA severity and their cephalometric S-H distance. The utility of the latter as a screening test cannot therefore be recommended as a substitute for existing diagnostic tests.