Efficacy of daytime continuous positive airway pressure titration in severe obstructive sleep apnoea.

The aim of this study was to evaluate manual nasal continuous positive airway pressure (nCPAP) titration during daytime polysomnography compared with conventional overnight titration for patients with severe obstructive sleep apnoea. Thirty-two patients who underwent daytime titration were retrospectively matched (for age, sex, body mass index and apnoea/hypopnoea index (AHI)) to a group titrated overnight during the same period. Successful titration was defined as the identification of the nCPAP level (effective nCPAP (Peff)) required to eliminate respiratory events during all sleep stages. After 3 months of therapy on nCPAP at Peff, nCPAP utilization history was obtained and a group of patients underwent a repeat polysomnogram (PSG) and completed a follow-up Epworth Sleepiness Scale (ESS) score. Initial titration was successful in 91% of daytime patients and 91% of overnight patients. The success of daytime titration was not related to diagnostic AHI or ESS score. Subjective nCPAP utilization was statistically similar in both groups. On the follow-up PSG, there were no significant differences between daytime (n=11) and overnight (n=11) patients in measures of sleep quality or respiratory disturbance. Both groups demonstrated similar and significant improvements in ESS score. These findings suggest that the effective nasal continuous positive airway pressure can be accurately established during daytime titration in a substantial proportion of severe, symptomatic obstructive sleep apnoea patients.

Accuracy of oximetry with thermistor (OxiFlow) for diagnosis of obstructive sleep apnea and hypopnea.

OBJECTIVES: To evaluate the diagnostic accuracy for obstructive sleep apnea and hypopnea (OSAH) of the OxiFlow (OF) device which combines oximetry with recording of thermistor airflow. DESIGN & SETTING: Patients scheduled for overnight diagnostic polysomnography (PSG) were studied with OF either simultaneously during laboratory PSG (L-OF, n=86), at home on a separate night (H-OF, n=66), or both (n=55). PATIENTS: 97 patients with suspected OSAH, of whom 40 had OSAH defined as an apnea-hypopnea index (AHI) of more than 15 events per hour of sleep on PSG. INTERVENTIONS: NA. MEASUREMENTS & RESULTS: The automated respiratory disturbance index (RDI) generated by the OF software considerably underestimated the AHI by PSG for both L-OF and H-OF. Altering the parameters for hypopnea identification by the software did not improve this. Visual inspection of the computerized OF tracings added considerable diagnostic information, but a manual count of RDI during visual review overestimated AHI. For the identification of cases vs. non-cases of OSAH, receiver operating characteristic area-under-the-curve statistics ranged from 0.77-0.90 for L-OF and from 0.71-0.77 for H-OF. Combining automated analysis with subsequent visual inspection of OF tracings yielded an overall sensitivity of 86% and specificity of 74% for the diagnosis of OSAH during H-OF recordings. Analysis of potential technician time saved indicated a benefit from the use of OF. CONCLUSIONS: OF has diagnostic utility for the identification of OSAH. However, because of hardware and software limitations, it is unclear whether this device is superior to oximetry alone.

Compliance with and accuracy of daily self-assessment of peak expiratory flows (PEF) in asthmatic subjects over a three month period.

Serial peak expiratory flow (PEF) assessment has been proposed in the clinical evaluation of asthma. In subjects attending the asthma clinic of a tertiary care hospital, we wanted to assess: 1) compliance in performing PEF; and 2) accuracy of a PEF-diary. Twenty adult asthmatic subjects, all using inhaled steroids, were asked to assess their PEF in the morning and evening with a VMX instrument (Clement Clarke Int., Colombus, OH, USA). This instrument, which incorporates a standard mini-Wright peak flow meter, stores PEF data on a computer chip. Subjects were not informed that the values were being stored. The mean duration of PEF monitoring was 89 days (range 44-131 days). For the total of 20 subjects, it was estimated that 3,482 values should have been written down and stored on the VMX computer chip. Whilst 1,897 values (54%) were written down, only 1,533 (44%) were stored, 425 values being invented. Morning and evening values were stored on 34% of days; and values were stored at least once a day on 55% of days. The values written down corresponded precisely to stored values 90% of the time, and were within +/- 20 L 94% of the time. We conclude that: 1) compliance with daily peak expiratory flow assessments is generally poor in chronic stable asthmatic subjects assessed on two visits separated by a 3 month period; and 2) a substantial percentage of values (22%) is invented. The unsatisfactory compliance with peak expiratory flow monitoring in this group of asthmatics on inhaled steroids underlines the need for similar studies on peak expiratory flow monitoring as part of an action treatment plan, and in more severe and brittle asthmatics.

Intussusception in children: reliability of US in diagnosis--a prospective study.

To assess the diagnostic value of ultrasound (US) in clinically suspected acute intestinal intussusception in children, the authors prospectively compared US and enema studies in 83 episodes. None of the cases negative at US proved to be intussusception at enema study (negative predictive value = 100%). The sensitivity of US was 100%, and the specificity was 88%. Most of the sonograms were initially obtained and examined by residents. Several unsuspected abnormalities were also found with US. The authors conclude that a few months of training in US appears to be sufficient for high-accuracy investigation of clinically suspected intussusception, enabling selection of those patients in need of an enema.