Value of nocturnal oxygen saturation as a screening test for sleep apnoea

Evaluation of the association between sleep apnea and polyunsaturated fatty acids profiles in patients after percutaneous coronary intervention

The long-term outcome is poor in patients with sleep apnea and cardiovascular disease. Polyunsaturated fatty acid (PUFA) is also known as an independent predictor for adverse clinical events. However, the profile of PUFA in sleep apnea patients with coronary artery disease (CAD) is still unclear. This study aimed to clarify the association between sleep apnea and PUFA profiles in patients with CAD. Two hundred seventy-four consecutive patients undergoing percutaneous coronary intervention (PCI) were screened for sleep apnea using nocturnal oximetry. Oxygen desaturation index down to 4% (4%ODI) ≥5 was used as an indicator of sleep apnea. Baseline characteristics, including PUFA profiles, were compared between patients with and without sleep apnea. Among 243 enrolled patients, 134 (55%) had sleep apnea. The sleep apnea group included a significantly higher rate of patients with obesity, insulin-requiring diabetes, peripheral artery disease (PAD), and a higher C-reactive protein level than the non-sleep apnea group. The sleep apnea group had a significantly lower eicosapentaenoic acid (EPA) to arachidonic acid (AA) ratio than the non-sleep apnea group (0.33 vs. 0.44, respectively, p = 0.024). Additionally, EPA value and EPA/AA ratio were significantly correlated with 4%ODI (r = -0.15, p = 0.028; r = -0.16, p = 0.019, respectively). Results of logistic regression analysis indicated that the comorbidities of obesity, PAD, heart failure and EPA/AA ratio had a significant association with sleep apnea. Our results suggested that patients with sleep apnea who underwent PCI had a lower EPA/AA ratio than those without sleep apnea, and EPA value and EPA/AA ratio were significantly correlated with 4%ODI.

Impact of sleep disordered breathing on carotid body size

We tested the hypotheses that: (1) carotid body size can be measured by computed tomographic angiography (CTA) with high inter-observer agreement, and (2) patients with sleep apnea exhibit larger carotid bodies than those without sleep apnea. A chart review was conducted from patients who underwent neck CTA and polysomnography at the Mayo Clinic between January 2000 and February 2015. Widest axial measurements of the carotid bodies, performed independently by two radiologists, were possible in 81% of patients. Intra-class correlation coefficients ranged from 0.93 to 0.95 (Right carotid body: 0.93; Left: 0.94; Average: 0.95). Widest axial measurements of the carotid bodies were greater in patients with sleep apnea (n=32) compared to controls (n=46, P-value range 0.02-0.04). After adjusting for age, no differences in carotid body size were observed between the patient groups (P-value range 0.45-0.59). We conclude carotid body size can be detected by CTA with high inter-observer agreement; however, carotid body size is not increased in patients with sleep apnea.

Sleep-related breathing disorders in the Shy-Drager syndrome. Observations on investigation and management

We report on 18 patients with the Shy-Drager syndrome who were referred for assessment of a sleep-related breathing disorder. The main symptoms of snoring, apnoea, stridor and daytime hypersomnolence were detailed and vocal cord movement graded by laryngoscopy as normal, mild weakness of abduction or near paralysis of vocal cord movement Sleep studies involving oximetry and observations were performed. Obstructive and central apnoeas were detected in six patients. Many patients with near paralysis of vocal cord abduction had normal sleep studies. Successful management strategies of obstructive cases included CPAP, nasal surgery and tracheostomy or arytenoidectomy alone or in combination. Sleep-related breathing disorders in the Shy-Drager syndrome may involve significant nocturnal desaturation; investigation with suitable medical or surgical treatment should be employed in these patients.

Interrelationships between body mass, oxygen desaturation, and apnea-hypopnea indices in a sleep clinic population

STUDY OBJECTIVES

To investigate the relationship between oxygen desaturation index (ODI), body mass index (BMI), and apnea-hypopnea index (AHI) in a large sleep clinic population.

DESIGN

Retrospective observational.

SETTING

Sleep disorders clinic.

PATIENTS OR PARTICIPANTS

11,448 individuals undergoing diagnostic polysomnography (PSG) at a sleep disorders clinic.

MEASUREMENTS AND RESULTS

Polysomnography were scored using Chicago criteria. ODI at 2%, 3%, and 4% threshold levels were derived. The study population was subdivided into BMI categories in steps of 5 kg/m(2). Mean ODI and the accuracy of ODI for detecting an AHI ≥ 15 (moderate-severe OSA) or ≥ 30 (severe OSA) were examined by BMI category, using the area under the curve (AUC) of receiver operator characteristic (ROC) curves for the 3 ODI thresholds. Based on AUC, ODI-3% performed best overall, achieving a significantly higher AUC than ODI-2% and ODI-4% for the diagnosis of moderate-severe OSA, and a higher AUC than ODI-2% for the diagnosis of severe OSA. When examining the effect of BMI, ODI-3% achieved a significantly higher AUC than ODI-2% in all BMI categories, and ODI-4% in non-obese subjects. The sensitivity of ODI for detecting OSA increased with BMI, while specificity decreased.

CONCLUSIONS

ODI-3% performed best overall, and when combined with appropriate clinical assessment, could be considered as an initial diagnostic test for OSA. OSA is more frequently associated with oxygen desaturation in obese subjects. BMI influences the accuracy of ODI for the diagnosis of OSA, and ODI should not be used in isolation as a test for OSA in subjects with a BMI below 25kg/m(2).

Validation of the WristOx 3100 oximeter for the diagnosis of sleep apnea/hypopnea syndrome

OBJECTIVE

To evaluate the diagnostic accuracy of the Nonin WristOx 3100 and its software (nVision 5.0) in patients with suspicion of sleep apnea/hypopnea syndrome (SAHS).

METHODS

All participants (168) had the oximetry and polysomnography simultaneously. The two recordings were interpreted blindly. The software calculated: adjusted O(2) desaturation index [ADI]-mean number of O(2) desaturation per hour of total recording analyzed time of > or = 2%, 3%, 4%, 5%, and 6% (ADI2, 3, 4, 5, and 6) and AT90-accumulated time at SO(2) < 90%. The ADI2, 3, 4, 5, and 6 and the AT90 cutoff points that better discriminated between subjects with or without SAHS arose from the receiver operating characteristic curve analysis. The sensitivity (S), specificity (E), and positive and negative likelihood ratio (LR+, LR-) for the different thresholds for ADI were calculated.

RESULTS

One hundred and fifty-four patients were included (119 men, mean age 51, median apnea/hypopnea index [AHI] 14, median body mass index [BMI] 28.3 kg/m(2)). The best cutoff points of ADI were: SAHS = AHI > or = 5: ADI2 > 19.3 (S 89%, E 94%, LR+ 15.5 LR- 0.11); SAHS =AHI > or = 10: ADI3 > 10.5 (S 88%, E 94%, LR+ 15 LR- 0.12); SAHS = AHI > or = 15: ADI3 > 13.4 (S 88%, E 90%, LR+ 8.9, LR- 0.14). AT90 had the lowest diagnosis accuracy. An ADI2 < or = 12.2 excluded SAHS (AHI > or = 5 and 10; S 100%, LR- 0) and ADI3 > 4.3 (AHI > or = 5 and 10) or 32 (AHI > or = 15) confirmed SAHS (E 100%).

CONCLUSIONS

A negative oximetry defined as ADI2 < or = 12.2 excluded SAHS defined as AHI > or = 5 or 10 with a sensitivity and negative likelihood ratio of 100% and 0%, respectively. Furthermore, a positive oximetry defined as an ADI3 > 32 (SAHS = AHI > or = 15) had a specificity of 100% to confirm the pathology.

Predictive value of automated oxygen saturation analysis for the diagnosis and treatment of obstructive sleep apnoea in a home-based setting

BACKGROUND

A portable monitor for the automated analysis of episodic nocturnal oxygen saturation or SpO(2) (the Remmers Sleep Recorder, RSR) has been proposed for the diagnosis of obstructive sleep apnoea-hypopnoea (OSAH). A study was undertaken to compare the diagnostic performance of automated analysis with the manual scoring of polygraphic data by a more comprehensive respiratory monitor (the Suzanne recorder) used simultaneously in their intended home environment.

METHODS

The respiratory disturbance indexes of the two monitors were compared in 94 consecutive adult patients suspected of having OSAH and who were deemed eligible for home-based investigation.

RESULTS

The RSR overestimated the number of respiratory events associated with a >or=4% fall in SpO(2) by 13% (p<0.005) but underestimated the number of apnoeas and hypopnoeas defined on the basis of respiratory variables alone or their association with a >or=4% fall in SpO(2) or autonomic arousals by 38-48% (p<0.0001). In addition to these significant biases, the limits of agreement in all instances were wide, indicating a poor concurrence between the two monitors.

CONCLUSION

The automated analysis of SpO(2) with the RSR cannot be substituted for the manual scoring of polygraphic data with the more comprehensive respiratory monitor in the diagnosis of OSAH in an ambulatory home-based setting.

Effect of amplitude criteria on operating characteristic of detection for OSAH events with oxygen saturation

Effect of amplitude criteria on the operating characteristics of algorithms for detecting OSAH events based on the analysis of oxygen saturation alone is investigated. The objective is to establish that there exists an oxygen desaturation level that leverages these algorithms to be more sensitive or more specific, irrespective of the differences in detection mechanism and database, a first ever attempt. Linear classification of algorithms from previous studies discovered that a drop in oxygen saturation of 3% or less makes the detection algorithms more sensitive while a drop of 4% or more makes it more specific. Results from two algorithms developed here also supported this. This finding explains the contradiction cited in the performance of algorithms from the different authors, which casts doubts on their detection ability. It could lead to the establishment of standard oxygen desaturation levels for screening and diagnosis of moderate/severe OSA, thus providing a more credible comparison basis for automated detection algorithms or even clinical tests.

Clinical significance of nocturnal oximeter monitoring for detection of sleep apnea syndrome in the elderly

OBJECTIVES

The sensitivity and specificity of overnight monitoring of arterial oxygen saturation (SaO(2)) using an oximeter were evaluated in elderly subjects who are being investigated for possible sleep apnea syndrome (SAS).

METHODS

Seventy-five consecutive elderly subjects with habitual snoring (47 men, 28 women; mean (+/-SE) age 75.5+/-0.9 years (range 65-94 years)) were studied. The SaO(2) was measured with an oximeter and a chart recorder during the night immediately before detailed polysomnographic studies. The SaO(2) recordings were classified by two observers as positive or negative using a number of significant oxyhemoglobin desaturation (SDS) of more than 2, 4, and 6%. The sensitivity of the oximeter alone for the recognition of the SAS was calculated as the number of true positive SaO(2) records divided by the total number of positive definitive (polysomnographic) records. The specificity was defined as the number of true negative SaO(2) records divided by the total number of negative definitive records.

RESULTS

Of the 75 subjects, 24 had moderate SAS (apnea index (AI)>15) and 55 had mild to moderate SAS (AI>5). The sensitivity and specificity of the dosimeter as a screening test were determined with the two diagnostic thresholds of the AI. For AI exceeding 5 or 15, the respective sensitivity by using the criterion of SDS of more than 4% was 85.5 or 91.7%, with corresponding specificity of 85.0 or 92.2%.

CONCLUSIONS

The nocturnal oximeter monitoring allows recognition of elderly subjects with a mild to moderate SAS, and 4% desaturation of SaO(2) is a candidate index to detect a significant number of apneas in elderly SAS patients with an oximeter.

Clinical significance of pulse rate rise during sleep as a screening marker for the assessment of sleep fragmentation in sleep-disordered breathing

OBJECTIVE

To assess the clinical utility of the frequencies of transient increases of pulse rate, non-invasively measured with a pulseoximeter, as an indirect indication of the degree of cortical arousal, measured conventionally on an electroencephalogram (EEG), in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients.

PATIENTS AND METHODS

Thirty-three consecutive patients referred with suspected OSAHS were studied. Polysomnography (PSG) with determination of esophageal pressure (Pes) and pulseoximetry was monitored to identify breathing-related EEG arousal (B-Ar) associated with apnea, hypopnea or respiratory effort and the frequencies of pulse rate increases. We also assessed the association of B-ArI (defined as the number of B-Ar per hour) with the pulse rate rise index (PRRI)-X(X=4-10) (defined as the number of pulse rate increases per hour). In addition, the sensitivity and specificity of PRRI for the assessment of a B-ArI cutoff point of 30 were calculated.

RESULTS

The sensitivity and specificity of pulseoximetry for different thresholds of PRRI-X(X=4-10) demonstrated that the greatest diagnostic accuracy for detecting frequent arousal (B-ArI > or =30) occurs at a cutoff point of 40 PRRI-6 with a sensitivity of 0.88 and specificity of 0.86. This point shows a significant area under the curve of 0.84. In addition, a statistically significant correlation between PRRI-6 and B-ArI (r=0.68, P<0.0001) was observed.

CONCLUSIONS

The transient increases in pulse rate measured by pulseoximetry during sleep may be a useful clinical marker for predicting the degree of arousal in OSAHS patients, and may, in addition, prevent cases with frequent respiratory effort related arousals from being overlooked. However, further studies are required to improve the confidence level of the PRRI and to investigate the causes of overestimation of EEG arousals.

Respiratory monitoring by means of an unattended device in children with suspected uncomplicated obstructive sleep apnea: a validation study

STUDY OBJECTIVE

To compare an unattended device for cardiorespiratory monitoring (POLY-MESAM; MAP; Martinsried, Germany) [P-M] with classic nocturnal polysomnography (PSG) for diagnosis of obstructive sleep apnea (OSA) in children.

DESIGN

Clinical setting.

PATIENTS

Twelve children (age range, 3 to 6 years) with highly suspected uncomplicated OSA who underwent PSG and P-M on 2 consecutive laboratory nights in a balanced manner.

MEASUREMENTS

Respiratory indexes were compared for P-M (automated analysis), hand-scored revised P-M (P-Mrev), and PSG. Analysis of contingency for cutoff levels of respiratory disturbance index (RDI) of 5 and 10 and level of agreement between P-M, P-Mrev, and PSG by the concordance method were evaluated.

RESULTS

Nine of twelve children (75%) had a PSG RDI > 5, while 41.7% had an RDI > 10, indicating moderate-to-severe OSA. P-M sensitivity (78%) increased with the increase of the RDI cutoff, and P-Mrev sensitivity reached 100% at the cutoff of 10. The specificity was low for RDI > 5 and increased only modestly at RDI > 10 (P-Mrev, 57%). Seven of 12 children (increasing to 9 children with P-Mrev) and 9 of 12 children (increasing to 11 children with P-Mrev) were correctly classified by the P-M unit when cutoffs of 5 and 10 were considered, respectively. As far as the agreement level is concerned, P-M underestimated the incidence of obstructive hypopnea and overestimated the number of central apnea cases. P-Mrev improved the latter measure.

CONCLUSION

Based on these data, the P-M device cannot be advocated for common use in a clinical setting, but it may have a role in urgent screening for highly suspected moderate-to-severe OSA.

Utility of oxygen saturation and heart rate spectral analysis obtained from pulse oximetric recordings in the diagnosis of sleep apnea syndrome

OBJECTIVES

We prospectively evaluate the spectral characteristics of nocturnal arterial oxygen saturation (SaO(2)) and heart rate variability obtained from pulse oximetric recording as a diagnostic test for obstructive sleep apnea (OSA).

SUBJECTS AND MEASUREMENTS

Three hundred referred outpatients with symptoms compatible with the diagnosis of OSA were studied using nocturnal pulse oximetric recording performed simultaneously with polysomnography. Power spectral analysis of SaO(2) and heart rate data were analyzed using fast Fourier transformation of a Hamming-windowed signal.

DESIGN AND RESULTS

Recording test results were classified as abnormal (suspicion of OSA) if the periodogram showed a peak in the period 30 to 70 s in either of the signals. A normal test result was defined as the absence of this peak in the periodogram in both signals. Two independent observers performed a single-blind evaluation. The total area of the periodogram (STOT), the ratio of the area enclosed in the periodogram within the period 30 to 70 s (S(30-70)), the ratio of the area enclosed in the periodogram within the period 30 to 70 s with respect to the total area of the periodogram (S), and the peak amplitude of the periodogram in the period 30 to 70 s (PA) were measured in both signals. The presence of a peak in the periodogram in either of the signals has a sensitivity of 94%, a specificity of 82%, a positive predictive value of 87%, and a negative predictive value of 92% with respect to the OSA diagnosis. The patients in the OSA group had higher values for STOT, S(30-70), S, and PA than the group without OSA.

CONCLUSIONS

SaO(2) and heart rate spectral analysis obtained by nocturnal pulse oximetry as well as the identification of a peak within 30 to 70 s in either signal could be useful as a diagnostic technique for patient with OSA.

Oximeter performance: the influence of acquisition parameters

STUDY OBJECTIVE

This study was designed to determine whether different desaturation indexes (DIs) would be obtained in patients with sleep-disordered breathing by systematically altering two acquisition parameters: the recording setting and the display mode.

DESIGN

Prospective clinical study.

SETTING

Community sleep-disorders center.

PATIENTS

The study included 75 patients who were suspected of having sleep-disordered breathing.

INTERVENTIONS

Each patient had simultaneous pulse oxyhemoglobin saturation (SpO2) traces at three recording settings (3 s, 6 s, and 12 s) during the diagnostic phase of split-night polysomnography. On-line and memory displays of those data at each recording setting were obtained. DIs for > or = 3% desaturation events per hour were calculated for each of the six traces.

RESULTS

The mean on-line DIs significantly differed from each other, with slower (longer) recording settings resulting in lower values than faster (shorter) settings. The memory DIs all significantly underestimated the on-line DIs. Pearson correlations ranged from 0.82 to 0.90 between the on-line/memory DI pairs, but Bland-Altman analysis detected disagreement at higher levels of disordered breathing.

CONCLUSIONS

These findings confirm that significantly different SpO2 data are obtained at various acquisition options. The recording setting and display mode parameters should be disclosed in all reports employing oximetry with the fastest recording setting and on-line display mode preferable for case finding of sleep-disordered breathing.

Improvement in neuropsychological performance following surgical treatment for obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is characterized by snoring and apnea during sleep leading to decreased oxygen saturation and disturbed sleep, excessive daytime sleepiness and neuropsychological disturbances. This study investigates cognitive neuropsychological abilities in a group of 53 OSAS patients before and after treatment with uvulopalatopharyngoplasty. General intellectual ability, verbal learning and memory as well as executive functioning were measured at baseline and 6 months postoperatively. After surgery there were significant improvements in verbal learning and memory (mean change -39, SD 57.3, p < 0.001), recall (mean change -24.3, SD 39.3, p < 0.001) and executive functioning (as assessed by percentage of errors on the Wisconsin Card Sorting Test; mean change -9.1, SD 15.7, p < 0.001). These improvements were in accordance with improvements in the degree of sleep apnea, the oxygen desaturation index (mean change -9.7, SD 15.9, p < 0.001) and arterial minimum oxygen saturation (mean change 4.5%, SD 10.2%, p < 0.01). Surgical treatment seems to improve verbal learning, memory and recall and executive functions in parallel with better oxygenation in OSAS.

Overnight pulse oximetry for sleep-disordered breathing in adults: a review

Pulse oximetry is a well-established tool routinely used in many settings of modern medicine to determine a patient's arterial oxygen saturation and heart rate. The decreasing size of pulse oximeters over recent years has broadened their spectrum of use. For diagnosis and treatment of sleep-disordered breathing, overnight pulse oximetry helps determine the severity of disease and is used as an economical means to detect sleep apnea. In this article, we outline the clinical utility and economical benefit of overnight pulse oximetry in sleep and breathing disorders in adults and highlight the controversies regarding its limitations as presented in published studies.

The effects of orthognathic surgery on pharyngeal airway dimensions and quality of sleep

Orthognathic surgery has been associated with airway narrowing and induction of sleep-related breathing disorders. Therefore, the pharyngeal airway dimensions of 32 orthognathic surgery cases were prospectively investigated, and the relationship between the surgery and sleep quality assessed. Digitized lateral cephalometric radiographs were used to compare oropharyngeal airway morphologies before and after surgery. Patients were assessed in two main surgical groups based on sagittal jaw relationship. A questionnaire was used to assess changes in daytime sleepiness. The mandibular surgery cases were also assessed by overnight domiciliary sleep monitoring. A significant decrease in the retrolingual airway dimension was found in all patients after mandibular setback surgery and a significant increase in this dimension after mandibular advancement. The questionnaire and sleep study revealed no significant changes in snoring incidence or apnoeic events after mandibular setback surgery. For the mandibular advancement group, a change in sleep quality was found, but only in cases with signs of a pre-existing sleep disorder.

The role of history, Epworth Sleepiness Scale Score and body mass index in identifying non-apnoeic snorers

Seventy-one adults referred with snoring over a 9-month period were assessed and their apnoeic-status determined by clinical assessment using symptoms suggestive of the obstructive sleep apnoea-hypopnoea syndrome, the Epworth Sleepiness Scale score (ESS) and body mass index (BMI). The results of clinical assessment were compared to that of overnight six-channel polysomnography where snoring noise level, pulse rate, capillary oxygen saturation, breathing effort, oronasal airflow and body position were monitored. Polysomnography detected an apnoea-hypopnoea index (AHI) of < 15 episodes/h in 61(86%) patients and an AHI of > or = 15 episodes/h in 10 (14%) patients. Clinical assessment alone identified 57 patients with AHI of < 15 episodes/h as 'non-apnoeic snorers' and six patients with AHI of > or = 15 episodes/h as 'apnoeic snorers'. The sensitivity of this method of clinical assessment in identifying the 'non-apnoeic snorers' from amongst patients referred with snoring was 93.4% and its specificity was 60% (P < 0.001).

Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnoea

BACKGROUND

The gold standard diagnostic test for obstructive sleep apnoea (OSA) is overnight polysomnography (PSG) which is costly in terms of time and money. Consequently, a number of alternatives to PSG have been proposed. Oximetry is appealing because of its widespread availability and ease of application. The diagnostic performance of an automated analysis algorithm based on falls and recovery of digitally recorded oxygen saturation was compared with PSG.

METHODS

Two hundred and forty six patients with suspected OSA were randomly selected for PSG and automated off line analysis of the digitally recorded oximeter signal.

RESULTS

The PSG derived apnoea hypopnea index (AHI) and oximeter derived respiratory disturbance index (RDI) were highly correlated (R = 0.97). The mean (2SD) of the differences between AHI and RDI was 2.18 (12.34)/h. The sensitivity and specificity of the algorithm depended on the AHI and RDI criteria selected for OSA case designation. Using case designation criteria of 15/h for AHI and RDI, the sensitivity and specificity were 98% and 88%, respectively. If the PSG derived AHI included EEG based arousals as part of the hypopnea definition, the mean (2SD) of the differences between RDI and AHI was -0.12 (15. 62)/h and the sensitivity and specificity profile did not change significantly.

CONCLUSIONS

In a population of patients suspected of having OSA, off line automated analysis of the oximetry signal provides a close estimate of AHI as well as excellent diagnostic sensitivity and specificity for OSA.

Evaluation of frequency and time-frequency spectral analysis of heart rate variability as a diagnostic marker of the sleep apnoea syndrome

The sleep apnoea/hypopnoea syndrome (SAHS) elicits a unique heart rate rhythm that may provide the basis for an effective screening tool. The study uses the receiver operator characteristic (ROC) to assess the diagnostic potential of spectral analysis of heart rate variability (HRV) using two methods, the discrete Fourier transform (DFT) and the discrete harmonic wavelet transform (DHWT). These two methods are compared over different sleep stages and spectral frequency bands. The HRV results are subsequently compared with those of the current screening method of oximetry. For both the DFT and the DHWT, the most diagnostically accurate frequency range for HRV spectral power calculations is found to be 0.019-0.036 Hz (denoted by AB2). Using AB2, 15 min sections of non-REM sleep data in 40 subjects produce ROC areas, for the DFT, DHWT and oximetry, of 0.94, 0.97 and 0.67, respectively. In REM sleep, ROC areas are 0.78, 0.79 and 0.71, respectively. In non-REM sleep, spectral analysis of HRV appears to be a significantly better indicator of the SAHS than the current screening method of oximetry, and, in REM sleep, it is comparable with oximetry. The advantage of the DHWT over the DFT is that it produces a greater time resolution and is computationally more efficient. The DHWT does not require the precondition of stationarity or interpolation of raw HRV data.

A new technique for laser-assisted uvulopalatoplasty: decision-tree analysis and results

OBJECTIVE

Report a new technique of laser-assisted uvulopalatoplasty (LAUP) for snoring performed as a one-stage procedure.

STUDY DESIGN

A decision-tree was used in a prospective study of 89 patients from April 1994 to May 1997. It included a fiberscopy and Muller's maneuver, rhinomanometry, pH monitoring, computed tomography scan to measure the pharyngeal lumen, pulse oximetry, and polysomnography in case of sleep apnea syndrome was suspected.

METHODS

The authors performed their LAUP technique on 43 patients (48.5%) whose snoring was mainly caused by the velum. This technique consists of scarifying the velum by vaporizing the mucosa and the submucosa along a rectangle extending from the palatal dimple to the uvula and having a width of 1.5 to 2 cm. Vaporization of the palatal arches follows without exceeding the junction of the anterior and posterior pillars in height. The uvula is cut if necessary, preserving a length of at least 0.5 cm. The other patients underwent different procedures according to the cause of snoring.

RESULTS

There was no significant difference between LAUP and uvulopalatoplasty (UPPP) regarding pain. No permanent phonatory disorders and no regurgitation occurred. Satisfaction evaluated on a scale ranging from 0 to 10 was equivalent for the two techniques: mean value = 7.68 (+/-2.18) for LAUP and 8.60 (+/-2.27) for UPPP. The mean follow-up was 17 months (range, 1-37 mo). Satisfaction was also identical for all techniques.

CONCLUSION

Our LAUP technique combined with other procedures according to a decision-tree is efficient and safe.

Sleep-disordered breathing in children with myelomeningocele

BACKGROUND

Although patients with myelomeningocele and the Chiari II malformation are known to have sleep apnea and respiratory control deficits, the prevalence, types, severities, and associations of sleep-disordered breathing (SDB) have not been adequately defined.

METHODS

A cross-sectional study of our myelomeningocele clinic population was undertaken to correlate polysomnographic results with historical data and findings from magnetic resonance imaging of the Chiari malformation, pulmonary function results, and nocturnal pulse oximetry.

RESULTS

A questionnaire survey of symptoms was available for 107 of 109 children (98% of the clinic population), and 83 patients agreed to undergo overnight polysomnography. Breathing during sleep was classified as normal in 31 cases (37%), mildly abnormal in 35 cases (42%), and moderately/severely abnormal in 17 cases (20%). Among the 17 patients with moderately/severely abnormal SDB, 12 patients had predominantly central apneas and 5 had predominantly obstructive apnea. Patients with a thoracic or thoracolumbar myelomeningocele, those who had previously had a posterior fossa decompression operation, those with more severe brain-stem malformations, and those with pulmonary function abnormalities were more likely to have moderately/severely abnormal SDB, relative risks (95% confidence intervals) 9.2 (2.9 to 29.3), 3.5 (1.3 to 8.9), 3.0 (0.9 to 10.5), and 11.6 (1.6 to 81.3), respectively. Failure of obstructive SDB to resolve after adenotonsillectomy in four patients suggested abnormal control of pharyngeal airway patency during sleep. Nocturnal pulse oximetry accurately predicted moderately/severely abnormal SDB with a sensitivity of 100% and a specificity of 67%.

CONCLUSIONS

The pathogenesis of SDB in patients with myelomeningocele involves the functional level of the spinal lesions, congenital and acquired brainstem abnormalities, pulmonary function abnormalities, disorders of upper airway maintenance, and sleep state. Polysomnography and nocturnal pulse oximetry should be performed in high-risk patients to detect and classify SDB.

Identification of obstructive sleep apnea in patients who snore

As the field of sleep medicine has evolved, the clinical implications of obstructive sleep apnea (OSA) in snoring patients have become well accepted. Recent advances in surgical therapy for snoring allow otolaryngologists to offer simple outpatient treatment to patients with this problem. However, because the incidence of OSA in snorers seeking medical attention is unknown, the appropriate pretreatment evaluation of these patients is a subject of continued debate. Ninety-four snoring patients were recruited for a study to determine the incidence of OSA in this highly selected population. Subjects answered an extensive sleep questionnaire to determine factors that might suggest a diagnosis of OSA. Level III ambulatory sleep studies were performed on each participant. The incidence of OSA in this group was 72% (42% severe and 30% mild to moderate). Twenty of the subjects with OSA also underwent formal level I sleep studies, and the diagnosis of OSA was confirmed in each instance. Although there was a relationship between body mass index and OSA and certain questions correlated with OSA, the sensitivity and specificity of these data alone or in combination were too low to recommend their use in lieu of a formal sleep study. Given the remarkably high incidence of OSA in this group, which may reflect that seen by otolaryngologists who treat snoring, a sleep study should be performed to diagnose OSA and institute therapy for this condition. Level III ambulatory monitoring devices may be the most cost-effective alternative for evaluating this high-risk population.

Validity of diurnal sleep recording performed by an ambulatory device in the diagnosis of obstructive sleep apnoea

The objective of this study was to compare the results of oxygen desaturations and sleep apnoea during a daytime nap (D) versus nocturnal sleep (N) evaluation, recorded by a portable multichannel monitoring device in patients with a clinical suspicion of obstructive sleep apnoea (OSA). Two polysomnographic studies were performed, by means of the Healthdyne NightWatch System, in 82 subjects (mean age 57.9 years). No difference was found in the apnoea + hypopnoea index (AHI) and mean SaO2 between D and N recordings. At an AHI threshold of 20, in the D recordings, compared to the N ones, the sensitivity was 91% and the specificity 100%. A good correlation was found for AHI and oxygen desaturation index (ODI) between the two experimental conditions (r = 0.89 and 0.79, respectively). Our study shows that D recordings seem to be accurate for OSA diagnosis in the majority of patients with a clinical suspicion of sleep apnoea syndrome.

Cost-effectiveness analysis of nocturnal oximetry as a method of screening for sleep apnea-hypopnea syndrome

STUDY OBJECTIVE

Determine the utility of nocturnal oximetry as a screening tool for sleep apnea-hypopnea syndrome (SAHS) compared with polysomnography (PSG).

DESIGN

Cost-effectiveness analysis based on retrospective review of overnight sleep studies.

SETTING

United States Air Force tertiary teaching hospital.

PATIENTS

One hundred consecutive patients evaluated for SAHS by overnight sleep study.

INTERVENTION

Participants underwent PSG and oximetry on the same night. Patients with obstructive sleep apnea had a continuous positive airway pressure trial.

MEASUREMENTS

Oximetry was abnormal when > or =10 events per hour occurred. Two criteria were evaluated. A "deep" pattern of > 4% change in oxyhemoglobin saturation to < or =90%, and a "fluctuating" pattern of repetitive short-duration fluctuations in saturation. The diagnostic accuracy of both methods was compared with PSG. Cost-effectiveness of screening oximetry was compared with PSG alone and use of split-night studies.

RESULTS

The fluctuating pattern had a greater sensitivity and negative predictive value, while the deep pattern had a greater specificity and positive predictive value. Oximetry screening using the fluctuating pattern was not as sensitive as PSG for detecting patients with mild disease; 17 of 28 patients (61%) with normal oximetry results had treatable conditions detected by PSG. Cost analysis showed that screening oximetry would save $4,290/100 patients but with considerable loss of diagnostic accuracy.

CONCLUSION

Screening oximetry is not cost-effective because of poor diagnostic accuracy despite increased sensitivity using the fluctuating pattern. Greater savings, without loss of diagnostic accuracy, may be achieved through increased utilization of split-night PSGs.

Home assessment of sleep disorders by portable monitoring

Ambulatory home monitoring has been employed for a number of applications. Portable sleep/wake recorders are useful for assessment of the hypersomnias, circadian sleep/wake disorders, parasomnias, and periodic movements in sleep. Wrist actigraphy can usefully approximate sleep versus wake state during 24 h and has been used for monitoring insomnia, circadian sleep/wake disturbances, and periodic limb movement disorder. Home monitoring of cardiopulmonary parameters can be employed for detection and follow-up of sleep-disordered breathing (sleep apnea, upper airway resistance syndrome). The techniques available for portable monitoring, although valuable, do not replace traditional in-laboratory polysomnography for full assessment of a sleep disorder.

Nocturnal and respiratory disturbances in Steele-Richardson-Olszewski syndrome (progressive supranuclear palsy)

Respiratory and sleep disturbances may be important causes of morbidity in Steele-Richardson-Olszewski syndrome but the frequency and character of nocturnal abnormalities remains uncertain. A prospective study of 11 patients with Steele-Richardson-Olszewski syndrome and age-matched control subjects was undertaken using clinical assessments, a structured sleep questionnaire, spirometry, static maximum inspiratory and expiratory pressures and nocturnal oximetry. The mean age of the Steele-Richardson-Olszewski syndrome patients was 63.2 (52-70) years and mean disease duration was 4.0 (2-6) years. There was moderate to severe motor disability in nine and mild to moderate dementia in eight. In the patients with Steele-Richardson-Olszewski syndrome the following abnormalities contributed to sleep disturbances significantly more frequently than in normal controls: depression, dysphagia, frequent nocturnal awakenings (usually associated with urinary frequency), immobility in bed, difficulty with transfers, impaired dressing and feeding. There was profound impairment of voluntary respiratory control whilst automatic and limbic control were well maintained. Nocturnal respiratory abnormalities were not present even in the most severely disabled. In Steele-Richardson-Olszewski syndrome sleep abnormalities are common; they relate to the cognitive, pseudobulbar and extrapyramidal disturbances and may therefore be amenable to symptomatic control.

The role of sleep-disordered breathing in essential hypertension

In recent years there have been numerous reports addressing the relationship between sleep-disordered breathing (SDB) and hypertension (HTN). This study investigated the relationship between SDB and BP after controlling for age, gross obesity, and notably, antihypertensive medications. Sixty-seven men and women between 30 and 60 years of age and between 0.90 to 1.5 times ideal body weight were studied. SDB was assessed over two nights of polysomnographic monitoring, and BP was measured over repeated visits to the hospital. The results indicate that respiratory disturbance index (RDI) independently predicts diastolic BP (DBP), accounting for 15% of the variance in DBP (p=0.02). In subjects with severe levels of SDB (RDI >30), RDI uniquely accounted for 36% of the variance in DBP (p=0.003). Interestingly, SDB was not independently related to systolic BP. The physiologic mechanisms responsible for these findings are currently being explored.

Sleep deprivation worsens obstructive sleep apnea. Comparison between diurnal and nocturnal polysomnography

Daytime polysomnography (DPG) has been suggested for diagnosis of obstructive sleep apnea syndrome (OSAS), because it is less expensive than whole-night polysomnography investigation (NPG). To ensure sleep during day recordings, patients are often instructed to stay awake the night preceding DPG. This procedure has been validated against NPG, and also against apnea mattress recordings combined with ear oximetry (AMO). Twenty patients with OSAS symptoms were examined with NPG and simultaneous AMO and 2 to 3 weeks later with DPG 3 to 4 h in the morning after 1 nights sleep deprivation. Median apnea-hypopnea index (AHI) of DPG was 37 (95% confidence interval [CI], 19 to 44), significantly higher than median AHI of NPG (14; 95% CI, 12 to 27), whereas median nocturnal oxygen desaturation index (ODI) (11; 95% CI, 9 to 25) did not differ significantly from median AHI of NPG. Sensitivity values for DPG increased from 81 to 100% when the criteria AHI greater than 5, greater than 10, greater than 15, and greater than 20 were used, respectively. Specificity values also increased with the AHI used as cutoff point, from 50% (AHI>5) to 75% (AHI>20). In AMO, there were one false-negative case and four nonclassifiable borderline cases. If these types of simplified tests for OSAS are used for diagnosis, the risk of both false-negative and positive results (DPG) or nonclassifiable borderline cases (AMO) must be considered. Since there was a significant increase in AHI in DPG after sleep deprivation in comparison to conventional NPG, the former procedure should not be used for staging of the disease. These results also stress the importance of advice to OSAS patients concerning regular sleeping habits.

Accuracy of oximetry for detection of respiratory disturbances in sleep apnea syndrome

STUDY OBJECTIVE

The cost and inconvenience of polysomnography make simplified techniques of screening desirable in the strategy of diagnosis of sleep apnea syndrome (SAS). We have evaluated, in a prospective study of 301 consecutive patients referred for suspected sleep disorders, an index (delta index) that detects apneic events by quantifying arterial oxygen saturation (SaO2) variability.

SETTING

Regional sleep laboratory taking referrals from general practitioners and specialists.

DESIGN

Classic polysomnography was the gold standard, with 15 apneas plus hypopneas per hour (RDI) being used as a threshold for definition of obstructive sleep apnea (OSA). Oximetry was recorded over the same night. Signal variability was quantified as a function of time, using digital processing of oximetric data. Sensitivity, specificity, and positive and negative predictive values of oximetry testing were calculated. A receiver operating characteristic (ROC) curve was constructed representing the comparative courses of sensitivity and 1-specificity at different thresholds of delta index.

RESULTS

Three hundred one patients were included (age, 56 +/- 12 years). Their RDI was 30 +/- 24. For a delta threshold at 0.6, the sensitivity of oximetry for the diagnosis of OSA was 98% and the specificity was 46%. The positive and negative predictive values for diagnosing SAS were 77% and 94%, respectively. The three false-negative cases had a relatively high awake SaO2 (97 vs 93.9 +/- 2.8%), a moderate RDI (23.3 +/- 1.6), and were less obese than the other patients (body mass index: 25 +/- 3 vs 33 +/- 8). The 58 false-positive cases had an RDI of 8 +/- 4, an awake SaO2 of 93.1 +/- 3.6 vs 94.1 +/- 2.6 for the rest of the population (p = 0.01). Finally, the false-positive cases had more airways obstruction (FEV1/VC = 72 +/- 13 vs 77 +/- 15%; p = 0.026). Using a delta value of 0.8 leads to a sensitivity of 90% with 19 false-negative cases but with a higher specificity of 75%.

CONCLUSIONS

A nocturnal oximetry test with a delta index below 0.6 is helpful in ruling out the diagnosis of SAS in patients being screened for this condition, as this yielded only three negative test results in 301 screening procedures.

Computer assisted pulse oximetry for detecting children with obstructive sleep apnea syndrome

A prospective study was carried out on 110 children undergoing tonsillectomy or adenotonsillectomy to evaluate the usefulness of computer assisted pulse oximetry (POM) as a screening tool for nocturnal obstructive sleep apnea episodes. Twenty-one healthy age-matched children served as a control group. A self-designed software (CAPO version 1.0) was used to analyse collected oximetric data. Pre-operatively up to 25% of children showed a characteristic pattern of repeated oxygen desaturations related to partial or complete airway obstruction, which was not seen in the matched group. Thirty-one percent had an oxygen desaturation index (ODI) of more than 2 phases/h, being significantly higher than in the matched group. These children could not be identified from history or clinical examination with an acceptable sensitivity. A second monitoring has been performed in 32 patients 5 days after surgery. The nocturnal cyclic oscillations of oxygen saturation resolved in almost all cases. Computer assisted POM is useful in predicting and grading nocturnal obstruction and adds decision making data for the treatment in children suspected of suffering from obstructive sleep apnea.

Home testing for pediatric obstructive sleep apnea syndrome secondary to adenotonsillar hypertrophy

The objective of this study was to determine the accuracy and practicality of home testing for pediatric obstructive sleep apnea syndrome (OSAS) secondary to adenotonsillar hypertrophy. Twenty-one children aged 2-12 years and referred for possible OSAS were studied twice, once at home and once in the sleep laboratory. The home test consisted of two parts: 1) a cardiorespiratory recording of saturation (SaO2), pulse rate, pulse waveform, electrocardiogram, and respiratory inductive plethysmography; and 2) an 8-hour videotape recording of the sleeping child. In the laboratory, standard nocturnal polysomnography including electroencephalography was performed. Experiences with another 62 children who underwent home testing alone were also reviewed and are reported. At home, saturation, respiratory, and video data were obtained 96.4 +/- 13.3% (mean +/- SD) 99.4 +/- 1.6%, and 90.0 +/- 78% of the time, respectively. The sleep efficiency was greater at home than in the laboratory, 91.1 +/- 3.9% vs. 86.1 +/- 7.2%, with a mean difference of 5.0% (P < 0.01). The median environmentally induced movement/arousal index was lower in the home than in the laboratory, 0.0 (inter-quartile range, 0.0-0.3 vs. 2.4/hr (inter-quartile range 1.2-4.2), with a median difference of 2.4/h (P < 0.001). Study duration, apnea/hypopnea index, desaturation index, respiratory and spontaneous movement/arousal indices, and oxygen saturation during sleep were similar for home and laboratory studies. Although neither sleep state nor PCO2 (transcutaneous or end-tidal) was measured in the home, this information would have modified patient management in, at most, one case. In the second group of 62 children, exclusively studied at home, all studies were successfully recorded despite a wide range of sleep efficiencies, apnea/hypopnea indices, and desaturation indices. We conclude that home testing, using a simplified cardiorespiratory montage plus video recording, is accurate and of practical use in the routine evaluation of OSAS in patients with adenotonsillar hypertrophy.

Validation of British Thoracic Society guidelines for the diagnosis of the sleep apnoea/hypopnoea syndrome: can polysomnography be avoided?

BACKGROUND

The British Thoracic Society report on the diagnosis and treatment of the sleep apnoea/hypopnoea syndrome (SAHS) suggests that, if the pulse oximetry baseline oxygen saturation is above 90%, then 15 4% oxygen desaturation/hour in bed will diagnose SAHS requiring treatment. The diagnostic outcome of applying these guidelines has been studied.

METHODS

One hundred patients referred to a district general hospital sleep clinic were recruited. After initial clinical assessment, overnight pulse oximetry measurements were performed, followed by full polysomnography at the regional laboratory.

RESULTS

Sixty nine patients underwent both pulse oximetry and polysomnography. All 10 patients with more than 15 4% desaturations/hour on pulse oximetry had SAHS confirmed on polysomnography (specificity = 100%). Twenty two patients with SAHS were misdiagnosed using pulse oximetry alone (sensitivity = 31%). These patients had low apnoea scores but high hypopnoea scores.

CONCLUSIONS

The BTS pulse oximetry criteria are highly specific when positive (specificity = 100%), but may miss patients with the SAHS who have hypopnoeic episodes which cause arousal but not significant oxygen desaturation (sensitivity = 31%). It should be emphasised that pulse oximetry alone does not always give sufficient information to discriminate between those patients with or without SAHS. Patients with "negative" pulse oximetry and symptoms of SAHS should undergo polysomnography or multi-channel recording.

The use of sound recording and oxygen saturation in screening snorers for obstructive sleep apnoea

It is desirable to screen snoring patients for obstructive sleep apnoea (OSA) prior to surgical treatment. We postulated that the addition of a sound profile would increase the value of overnight oxygen saturation (SaO2) as a screening method. Thirty-nine polysomnographic studies including sound level measured by calibrated meter were performed on snorers being considered for uvulopalato-pharyngoplasty (UPPP). Polysomnography showed an apnoea/hypopnoea index (AHI) > or = 15 per hour of sleep in seven subjects. Two experienced observers independently, without knowledge of other data, classified paper records of SaO2 alone and SaO2 plus sound level obtained during polysomnography as OSA 'unlikely', 'equivocal' or 'definite'. The addition of sound to SaO2 reduced the number of equivocal results from 14 to six and increased the number classified as 'definite' or 'unlikely'. The sensitivity of oximetry +/- sound increased as the threshold AHI used in the definition of OSA increased; addition of sound improved recognition of mild OSA without impairing specificity.

[Sleep apnea syndrome in obese patients: are there any predictive factors ?]

The aim of this study was to determine whether clinical, spirometric, or arterial blood gas data could predict sleep apnea syndrome (SAS) among obese patients with at least one functional complaint. Eighty three obese patients, 46 males and 37 females, aged 53.2 +/- 13.7 years, with a body mass index (BMI) above 30 kg/m2 were investigated with: clinical questionnaire; pulmonary function tests; arterial blood gas measurements; nocturnal monitoring of oronasal airflow, thoracic and abdominal movements, and arterial oxygen saturation. Thirty five patients (42.2%) had a SAS, 18 (26.7%) had nocturnal oxygen desaturations, and 30 (36.1%) had a normal nocturnal monitoring. There were 63% males in the SAS group and 32% in the group without SAS (P < 0.01). Age, weight, frequency of systemic hypertension, frequency of each clinical symptom, spirometric and arterial blood gas data were identical in the two groups. In conclusion, rate of SAS is very high in obese patients presenting a BMI above 30 and at least one functional complaint. No predictive test is identified.

Sleep related hypoxaemia in hypertensive and normotensive men

BACKGROUND

An association between hypertension and obstructive sleep apnoea (OSA) has been found by some researchers but remains controversial. Since such an association would have important implications for the investigation and management of hypertension, the rate of nocturnal hypoxaemic episodes has been compared in hypertensive and normotensive men.

METHODS

The study was carried out in the community in Belfast and its environs. Thirty four men with mild to moderate hypertension aged 40-64 years were identified from general practice and a hypertension clinic. Normotensive men, matched for age and body mass index, were selected from a community survey. Subjects answered a sleep questionnaire and underwent overnight pulse oximetry at home. Computer analysis of the results gave the number and magnitude of dips in oxygen saturation (SaO2 dips, 4% or greater).

RESULTS

The median number of SaO2 dips/hour for hypertensives was 2.0, and for normotensives was 0.8. Lowest SaO2 and mean SaO2 levels were significantly lower in the hypertensive group. Only one subject had a rate of SaO2 dips/hour greater than five and symptoms suggestive of OSA.

CONCLUSIONS

Both hypertensive and normotensive men had relatively few episodes of nocturnal hypoxaemia. The small increase in the rate of SaO2 dips in hypertensive subjects has not yet been fully explained. These results imply that OSA is not common in hypertensive subjects and is unlikely to be an important cause of hypertension.

Model for investigating snorers with suspected sleep apnoea

BACKGROUND

Overnight polysomnography is expensive and time consuming. An approach based on a logistic regression model and overnight pulse oximetry has been developed to determine which of the snorers referred to our sleep laboratory need polysomnography.

METHODS

The variables entered in the regression model were derived from questionnaires completed by 95 habitual snorers and 89 patients with obstructive sleep apnoea. The resulting regression equation included weight, height, sex, witnessed episodes of apnoea, and reports of falling asleep when reading. This prediction equation was applied to a sample of 116 consecutive patients referred for investigation of heavy snoring. Pulse oximetry data on the 116 test subjects were obtained during polysomnography and analysed separately. Pulse oximetry was judged to indicate obstructive sleep apnoea when it showed cyclic oscillations of oxyhaemoglobin saturation or heart rate, or both, for more than 30 minutes during the study night.

RESULTS

A cut off probability of 0.31 gave the prediction model a sensitivity of 94% to predict an apnoea-hypopnoea index above 10, with a specificity of 45%. When this cutoff point was used to predict an apnoea-hypopnoea index of over 20 sensitivity was 95% and specificity 41%. Combined with oximetry our regression model had a sensitivity of 100% for predicting an apnoea-hypopnoea index of more than 10. On the other hand, all patients with negative results from oximetry and a probability value below 0.31 had an apnoea-hypopnoea index lower than 10 according to polysomnography.

CONCLUSIONS

It is concluded that snorers with negative results from oximetry classified as not having obstructive sleep apnoea according to this model do not need polysomnography.