Baseline Respiratory Disturbance Index Research Articles

A randomized crossover study comparing two mandibular repositioning appliances for treatment of obstructive sleep apnea

The purpose of this study was to determine whether treatment outcomes vary according to the design of the mandibular repositioning appliance (MRA). Two titratable MRA's were compared. The designs differ in advancement hardware and configuration of acrylic both in bulk and interocclusal contact. The primary treatment outcome was the Respiratory Disturbance Index (RDI). Other outcomes that were compared included Sleep Apnea Quality of Life Index (SAQLI), Epworth Sleepiness Scale, oxygen saturation, and subjective feedback regarding experiences with the appliances. Twenty-four subjects were recruited from consecutive referrals for MRA therapy following diagnosis of obstructive sleep apnea (OSA) by polysomnography. Subjects were randomly assigned to a treatment arm of the crossover study. Each subject underwent an initial sleep study with a type III home monitor to establish a baseline RDI. Subjects were then treated with one of the two MRAs determined by random assignment. The MRA self-titration phase was monitored until a treatment position was determined, and the home sleep study was repeated. After a 2-week period without any OSA treatment, subjects received the second MRA and the self-titration treatment protocol was repeated. At completion of treatment with each appliance, subjects answered questionnaires and underwent a sleep study with the type III monitor. The outcome data for each appliance were compared using analysis of variance. Eighteen subjects completed the treatment protocol. There were no significant statistical differences in treatment outcomes between the two appliances. There was a statistically significant (p ≤ 0.05) preference for a MRA design with minimal coverage of teeth and palate. The subjects' appliance selection was consistent with a corresponding reduction in SAQLI score for the selected appliance. Although no statistically significant difference was observed between the two appliances in the outcomes measured, there was a trend toward greater improvement with the appliance with less acrylic resin bulk and less interocclusal contact. MRA selection should favor titratable, unobtrusive designs with appropriate construction to promote acceptance and adherence to MRA therapy.

Non-Invasive Characterization of Electrical Remodeling in a Risk Factor Modification Program

Introduction: Weight management in obese subjects is suggested to improve cardiac remodelling. Little is known about the atrial electrical changes that accompany weight reduction.Methods: In a randomized-controlled trial (ANZCTR: 12610000497000), 46 subjects with BMI >27 in sinus rhythm were randomized to a comprehensive risk factor management program or general lifestyle advice, and followed-up for 12-months. Metabolic profiles, pharmacotherapy, BMI, waist circumference (WC) and body surface area (BSA) were recorded. Digital analysis of 12-lead ECGs was used to assess P-wave duration (PWD) and area (PWA) and indexed to BSA (PWD-I and PWA-I), at baseline and at completion of the study.Results: Subjects were well matched for all baseline characteristics (25 active, 21 controls). Mean follow-up was 11.6±1.6 months. Using the paired-sample t-test, significant reduction was seen in all indices at 12-months (PWD; P<0.001, PWA; P=0.001, PWD-I; P=0.014, PWA-I; P=0.016) in the active group. No significant difference was seen in the control group. Using regression analysis with intention-to-treat, active group allocation was predictive of abbreviated P-wave indices (P=0.019). Controlling for age, gender, baseline respiratory disturbance index (RDI), ΔBMI, ΔWC and ΔBSA, significant correlation remained between shortening of PWD-I and number of anti-hypertensive medication used (P=0.026). Conclusion: A structured comprehensive risk factor management program, with aggressive hypertension management and weight reduction, is associated with a favourable improvement in ECG-derived indices of atrial electrical remodelling.

Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients with Obstructive Sleep Apnea

Positive airway pressure (PAP) devices are used to treat patients with sleep related breathing disorders (SRBDs), including obstructive sleep apnea (OSA). After a patient is diagnosed with OSA, the current standard of practice involves performing attended polysomnography (PSG), during which positive airway pressure is adjusted throughout the recording period to determine the optimal pressure for maintaining upper airway patency. Continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BPAP) represent the two forms of PAP that are manually titrated during PSG to determine the single fixed pressure of CPAP or the fixed inspiratory and expiratory positive airway pressures (IPAP and EPAP, respectively) of BPAP for subsequent nightly usage. A PAP Titration Task Force of the American Academy of Sleep Medicine reviewed the available literature. Based on this review, the Task Force developed these recommendations for conducting CPAP and BPAP titrations. Major recommendations are as follows: (1) All potential PAP titration candidates should receive adequate PAP education, hands-on demonstration, careful mask fitting, and acclimatization prior to titration. (2) CPAP (IPAP and/or EPAP for patients on BPAP) should be increased until the following obstructive respiratory events are eliminated (no specific order) or the recommended maximum CPAP (IPAP for patients on BPAP) is reached: apneas, hypopneas, respiratory effort-related arousals (RERAs), and snoring. (3) The recommended minimum starting CPAP should be 4 cm H2O for pediatric and adult patients, and the recommended minimum starting IPAP and EPAP should be 8 cm H2O and 4 cm H2O, respectively, for pediatric and adult patients on BPAP. (4) The recommended maximum CPAP should be 15 cm H2O (or recommended maximum IPAP of 20 cm H2O if on BPAP) for patients or = 12 years. (5) The recommended minimum IPAP-EPAP differential is 4 cm H2O and the recommended maximum IPAP-EPAP differential is 10 cm H2O (6) CPAP (IPAP and/or EPAP for patients on BPAP depending on the type of event) should be increased by at least 1 cm H2O with an interval no shorter than 5 min, with the goal of eliminating obstructive respiratory events. (7) CPAP (IPAP and EPAP for patients on BPAP) should be increased from any CPAP (or IPAP) level if at least 1 obstructive apnea is observed for patients or = 12 years. (8) CPAP (IPAP for patients on BPAP) should be increased from any CPAP (or IPAP) level if at least 1 hypopnea is observed for patients or = 12 years. (9) CPAP (IPAP for patients on BPAP) should be increased from any CPAP (or IPAP) level if at least 3 RERAs are observed for patients or = 12 years. (10) CPAP (IPAP for patients on BPAP) may be increased from any CPAP (or IPAP) level if at least 1 min of loud or unambiguous snoring is observed for patients or = 12 years. (11) The titration algorithm for split-night CPAP or BPAP titration studies should be identical to that of full-night CPAP or BPAP titration studies, respectively. (12) If the patient is uncomfortable or intolerant of high pressures on CPAP, the patient may be tried on BPAP. If there are continued obstructive respiratory events at 15 cm H2O of CPAP during the titration study, the patient may be switched to BPAP. (13) The pressure of CPAP or BPAP selected for patient use following the titration study should reflect control of the patient's obstructive respiration by a low (preferably 3 hr).

Symptoms of Depression in Individuals With Obstructive Sleep Apnea May Be Amenable to Treatment With Continuous Positive Airway Pressure

To assess the reversibility of symptoms of depression using continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA). Patients referred to our center for evaluation of OSA who had a respiratory disturbance index (RDI) > or = 15 and who demonstrated a significant response to CPAP (> or = 50% drop in RDI) were evaluated for the symptoms of depression using the Beck Depression Inventory (BDI), and then reassessed after 4 to 6 weeks of treatment with CPAP at home. In this group of patients, the institution of CPAP therapy resulted in a significant (p < 0.0001) decrease in those symptoms of depression as assessed by the BDI (BDI at baseline, 4.1 +/- 3.7; BDI after CPAP, 1.0 +/- 2.0). This change in BDI was noted both in those individuals who had received an antidepressant prescription prior to referral, and in those who had not. An analysis of variance failed to reveal any effect on these data related to gender or baseline RDI. Patients with OSA may present to their primary care physician with symptoms suggesting a diagnosis of depression. In some of these individuals, the symptoms of depression may be ameliorated with CPAP.

Three-dimensional computed tomography and polysomnography findings after extended uvulopalatal flap surgery for obstructive sleep apnea

Objectives Using both sleep physiological parameters and image data to evaluate the efficacy of extended uvulopalatal flap (EUPF) surgery in the treatment of obstructive sleep apnea (OSA). Material and methods Fifty patients with OSA underwent EUPF that consisted of bilateral tonsillectomy, dissection and removal of the submucosal adipose tissue of the soft palate and supratonsillar areas, and imbrications and repositioning of the denuded uvulopalatal flap. Polysomnography (PSG) and 3-dimensional computed tomography (3-D CT) data were obtained at baseline and 6 months postoperatively. Good response to surgery was defined as a reduction of the respiratory disturbance index (RDI) to less than 20 events/h and a greater than 50% reduction of the baseline RDI. Results Forty-two patients (84%) achieved good results. The RDI and minimal O 2 saturation improved significantly ( P < .0001) after EUPF. The postoperative 3-D CT evaluation showed a significant increase in the retropalatal space ( P < .0001). The preoperative lateral diameter of retropalatal space was predictive of the change of RDI (R 2 = 0.15, P = .05). The effect of increased retropalatal space ( r = 0.59, P = .0415) was significant in patients with baseline RDI ranged from 31 to 60 events/h. Conclusions With special emphasis on the removal of palatal fat, EUPF appeared to be effective in the reduction of sleep apnea in selected patients. 3-D CT proved that this technique was effective in widening the upper airway by relieving the retropalatal obstruction.

Multilevel temperature-controlled radiofrequency therapy of soft palate, base of tongue, and tonsils in adults with obstructive sleep apnea.

The concept of two-level pharyngeal collapse in patients with obstructive sleep apnea is too simplified. Aggressive multilevel surgeries addressing several airway segments, including skeletal surgery, demonstrate improved success rates. The study aimed to evaluate the safety and efficacy of multilevel radiofrequency application to soft palate, tonsils, and base of tongue in 16 white patients (mean age, 56.9 +/- 11.1 y; mean body mass index, 27.3 +/- 2.6 kg/m2) with obstructive sleep apnea. There was one dropout. Therapeutic effects after one treatment session were assessed 20.6 +/- 12.6 weeks postoperatively. Treatment outcome measurements were based on Epworth Sleepiness Scale, Likert scales, and polysomnography. Every patient received 16 treatment sites with a total dose of 9750 J radiofrequency energy into soft palate, base of tongue, and tonsils. Success was defined as respiratory disturbance index equal to or less than 20 or at least 50% improvement if baseline respiratory disturbance index was less than 20. Statistical analysis was determined with the Spearman rank test. Mean score on Epworth Sleepiness Scale decreased from 11.1 to 8.2 (P =.0001). Of the patients, 53.3% reported improvement of their daytime sleepiness. Snoring was assessed with 10-point Lickert scale, and score decreased from 7.5 to 4.9 (P =.08). Mean respiratory disturbance index decreased from 32.6 +/- 17.4 to 22.0 +/- 15.0 (P =.003). By our definition of success, 5 of 15 patients (33%) have been treated successfully surgically and 4 of 15 (27%) had remarkable improvement after one treatment session; 1 patient (6.6%) demonstrated deterioration. There were two adverse effects, one superficial ulceration of the soft palate and one unilateral tonsillar abscess formation, with an overall complication rate of 13.3% for our patients and 0.41% for all treatment sites (n = 240). Moderate to severe obstructive sleep apnea usually requires multilevel pharyngeal surgery. Radiofrequency offers the potential of altering the upper airway on different sites.

Predictors of longitudinal change in sleep-disordered breathing in a nonclinic population.

To quantify and identify the determinants of the 5-year change in the respiratory disturbance index (RDI). Longitudinal cohort study (Cleveland Family Study). Multivariate analyses were used to quantify baseline RDI and RDI change. Community-based study. 486 cohort members (62% from families of probands with sleep-disordered breathing [SDB])--mean age 31.6 +/- 17.9 (SD) years, 60% female, 21% Black ethnicity--who underwent 2 assessments over 5.3 +/- 0.9 (SD) years. NA. The RDI was measured twice over approximately 5 years with in-home monitoring. Symptoms and medical histories were obtained from standardized questionnaires, and weight, height, and blood pressure were measured. The prevalence of SDB (defined by a RDI > or = 15), increased from 13.7% to 23.4% (P < 0.01) in men and from 8.3% to 11.4% (P = 0.13) in females. Baseline and follow-up mean RDIs were 6.0 +/- 10.0 and 8.6 +/- 14.3; both were higher in older individuals, in men, and in those with a higher body mass index. Median 5-year change in RDI varied nonlinearly with age (-0.1, 1.1, 2.3, and 0.9, for those < 18, 19-40, 41-54, and > or = 55 years, respectively) and obesity (2.8 vs -0.1, for the top versus lowest body mass index quartile). The effects of changing weight and aging varied in population subgroups. At any given age and weight, the RDI increased less in women. Longitudinal change in the RDI varies nonuniformly with age, sex, and weight. Older heavier men may experience the highest rate of increase in RDI over time and, thus, may benefit most from prospective monitoring.

Therapy with nCPAP: incomplete elimination of Sleep Related Breathing Disorder.

Correct assessment of the overall treatment effectiveness requires knowledge about therapy compliance and efficacy. This study aimed to determine overall long-term apnoea alleviation after continuous positive airway pressure (CPAP) in a complete sleep laboratory cohort. Out of 209 consecutive CPAP candidates (mean age 57+/-12 yrs, body mass index (BMI) 30.0+/-5.1 kg x m2, respiratory disturbance index (RDI) 32.9+/-29 h), follow-up treatment was performed in 149 of them at 9, 18 and 30 months after CPAP prescription. Compliance with CPAP (machine run time/days CPAP available) was adjusted for the individual subjective sleep-time. Apnoea alleviation was defined as adjusted compliance multiplied by the CPAP effect (RDI with CPAP applied), remaining RDI was calculated. The baseline RDI, age or BMI in 75 patients, who did not tolerate nasal continuous positive airway pressure (nCPAP), did not differ from those accepting CPAP (acceptors, n=74). In acceptors at 9 months follow-up RDI with CPAP applied was 1.4+/-2.6 (CPAP effect, n=66), mean CPAP use was 3.6+/-2.5 x 24 h(-1) (n=68), mean apnoea alleviation was 52.4+/-32.0% (range 1-100%, n=47), the average remaining whole-night RDI was 17.8+/-26. At 9, 18 and 30 months (n=47), the mean daily CPAP use increased from 3.6+/-2.5 h to 4.1+/-2.5 h and 4.4+/-2.4 h (p<0.01). Effectiveness of continuous positive airway pressure is potentially high but acceptance was low. When accounting for sleep-time, its actual effect and use, only 50% adjusted continuous positive airway pressure effectiveness was observed.

Sleep disordered breathing and cognitive function in a retirement village population.

Sleep disordered breathing (SDB) may be associated with cognitive dysfunction in non-demented elderly people. A random sample of 96 retirement village residents were given both neuropsychological assessment and overnight sleep monitoring with a portable microprocessor based system (Vitalog PMS-8). Respiratory disturbance index (RDI) was calculated as the number of apnoeas and hypopnoeas per hour of sleep. RDI was not associated with 'memory', 'verbal', and 'motor' factors identified from the analysis of cognitive tests, but was associated with the 'cerebral efficiency' factor (R2 = 0.21, p less than 0.0001). Seventy-three subjects had repeat neuropsychological tests, median time to follow-up being 17 months. Baseline RDI did not predict changes in scores on the two factors identified from the second analysis. We conclude that mild to moderate disturbance of breathing during sleep is not associated with cognitive dysfunction in non-demented subjects.