Titration Polysomnogram Research Articles

Palate shape is associated with Unilateral Hypoglossal Nerve Stimulation Outcomes.

The aim was to determine the potential association between palate shape and unilateral hypoglossal nerve stimulation (HNS) outcomes. Preoperative drug-induced sleep endoscopy (DISE) videos were reviewed and scored by 3 blinded reviewers to determine airway narrowing at the hard-soft palate junction (HP), soft palate genu, and inferior velum, as described by Woodson (2014). Scoring was as follows: 1-open airway, 2-narrow, 3-severe narrowing. Overall palate shape (oblique, intermediate, or vertical) was determined based on prior criteria. Successful surgical treatment was defined by the HNS titration polysomnogram as a reduction of ≥50% in the apnea-hypopnea index (AHI) to <15 events/h. Of 332 adults, the majority was male (77%) with an average BMI of 29.2 ± 3.6 kg/m2 . Overall success rate was 73%. Success rate was lower in patients with vertical palate shape compared with the other shapes (56% vs. 75%, p = 0.029). HP score 3 compared with scores 2 and 1 was associated with lower success rates (60% vs. 76%, p = 0.028), but genu and velum scores were not associated with outcomes. Patients with both HP score 3 and complete oropharyngeal lateral wall-related obstruction had notably worse outcomes (22% vs. 74%, p = 0.026). HP score 3 (OR 0.45, 95%CI 0.22-0.92) and vertical palate shape (OR 0.33, 95%CI 0.15-0.78) were independently associated with lower odds of surgical response after adjustment for DISE findings, age, gender, and BMI. Vertical palate shape and narrowing at the hard-soft palate junction are independently associated with lower HNS surgical success rates. 3 Laryngoscope, 134:981-986, 2024.

Long-term trends in body mass index throughout upper airway stimulation treatment: does body mass index matter?

Upper airway stimulation is a surgical option for patients with obstructive sleep apnea who fail other forms of noninvasive treatment. Current guidelines recommend a baseline body mass index (BMI) below 32 kg/m2 for eligibility. In this study, we identify trends in BMI before and after upper airway stimulation to characterize the influence of BMI on treatment success. Patients underwent upper airway stimulation implantation between 2016 and 2021. Sleep study data were collected from preoperative and most recent postoperative sleep study. BMI data were collected and compared across the following time points: preoperative sleep study (BMI-1), initial surgeon consultation (BMI-2), surgery (BMI-3), titration polysomnogram (BMI-4), and second postoperative sleep study (BMI-5). Patients were categorized into groups (BMI ≥32 [BMI32], 25 ≤ BMI <32 [BMI25], BMI <25 [BMI18]) based BMI-1, and clinical outcomes were compared. 253 patients were included. The BMI32 group showed a significant decrease in BMI between BMI-1 and BMI-3 (33.9 vs 32.2; P < .001) and a significant increase in BMI between BMI-3 and BMI-5 (32.2 vs 33.0; P = .047). Apnea-hypopnea index improvement and treatment success rate were not significantly different between groups. On univariate and multivariable logistic regression, a lower BMI-5 was significantly predictive of treatment success (odds ratio: 0.88; 95% confidence interval: 0.79-0.97; P = .016). BMI-5 was also significantly associated with improvement in apnea-hypopnea index (P = .002). Other BMI time points were not associated with measures of treatment success. Reduced BMI after upper airway stimulation implantation, as opposed to baseline BMI, predicted treatment success. These findings may guide patient counseling, with implications for long-term adherence and therapy success. Renslo B, Virgen CG, Sawaf T, etal. Long-term trends in body mass index throughout upper airway stimulation treatment: does body mass index matter? J Clin Sleep Med. 2023;19(6):1061-1071.

Wavelet-based CNN for Predicting PAP Adherence Using Overnight Polysomnography Recordings: a Pilot Study.

Obstructive sleep apnea (OSA) is a common sleep disorder. Positive airway pressure (PAP) therapy is the first-line treatment, while its effectiveness is significantly limited by incomplete adherence in many patients. This work aims to find a predictive association between data from in-laboratory sleep studies during treatment (PAP titration polysomnogram, or PSG) and PAP adherence. Based on a PAP titration PSG database, we present a pipeline to develop a wavelet-based deep learning model and address two challenges. First, to tackle the problem of extremely long overnight PSG signals, it randomly draws segments and extracts features locally. The global representation for the entire signal is achieved by local feature P-norm pooling. Second, to tackle the problem of limited dataset size, the pre-trained EfficienNet-B7 is used as an unsupervised feature extractor to transfer ImageNet knowledge to PSG signals in the wavelet domain. The trained pipeline achieves 78% balanced accuracy and 83% AUC on the test set using airflow and frontal EEG signals, which, we believe, is a compelling result as a pilot study.

859 Trial of average volume-assured pressure support (AVAPS) to treat hypoventilation in a child with rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) and systolic heart failure

Abstract Introduction ROHHAD syndrome is a rare disorder of respiratory control and autonomic nervous system regulation with endocrine abnormalities. Although children may present with obstructive sleep apnea, their blunted respond to hypoxemia and hypercapnia is a life-threating feature, often leading to cardiorespiratory arrest. There is limited literature regarding non-invasive positive pressure ventilation (NIPPV) in these children. We report a trial of AVAPS in a child with ROHHAD syndrome. Report of case(s) Our patient is a 6-year-old male with history of rapid weight-gain (49.9 kg in 2.5 years), type-2 diabetes, and mild OSA who presented to an outside hospital (OSH) in March 2020 with acute hypercapnic hypoxemic respiratory failure. He required bilevel PAP therapy, steroids, and bromocriptine for thermoregulatory dysfunction. His clinical presentation, along with negative PHOX2B gene mutation and absence of parenchymal lung disease on chest computerized tomography suggested a diagnosis of ROHHAD syndrome. Outpatient, he was successfully transitioned to empiric AVAPS therapy. In November 2020, he presented again to an OSH in hypercapnic hypoxemic respiratory failure with new systolic heart failure with ejection fraction of 28%. After clinical stabilization, he was transferred to our hospital on CPAP 10 cmH20 with 100% FiO2 for further management. Awake blood gas was consistent with chronic hypercapnic respiratory failure; therefore, the patient was placed initially on bilevel PAP therapy empirically until an inpatient bilevel PAP titration polysomnogram was conducted. The patient remained hypercapnic and was converted to continuous AVAPS therapy starting at a tidal volume of 8.6mL/kg based on ideal body weight. AVAPS was titrated until achieving adequate ventilation, but the patient was unable to tolerate continuous NIPPV. Because of his heart failure in the setting of expected worsening respiratory failure, the decision was made to pursue tracheostomy placement for invasive positive pressure ventilation. Conclusion ROHHAD syndrome is a rare disorder that begins within the first decade of life, making adherence to daytime NIPPV difficult. This case illustrates a trial of AVAPS in a child with ROHHAD syndrome prior to tracheostomy placement. It highlights the need for future research in advanced ventilatory support strategies in children. Support (if any):

572 Utility of Split Night Polysomnograms in Children

Abstract Introduction Overnight in-lab polysomnograms (PSG) are the gold standard for diagnosis of sleep disordered breathing in children. As the wait time for adenotonsillectomy (T &amp; A) at our institution was several months, we implemented split night PSGs with positive airway pressure (PAP) during the initial diagnostic PSG if AHI&amp;gt;30 (Emergency SNPSG). Planned SNPSG were performed on children who are undergoing PSG after T &amp; A, eliminating follow-up titration PSG if the PSG is positive for OSA (residual AHI&amp;gt;10/hour). We present data on the outcomes of the SNPSG. Methods Retrospective chart review of consecutive SNPSGs done over last 2 years at our institution was performed. Data on SNPSGs (planned or emergency), age, sex, diagnostic study duration, diagnostic study AHI, PAP pressure and subsequent PAP adherence were collected. Data on sleep efficiency, arousal, sleep architecture, REM sleep were compared between diagnostic and titration part of the SNPSG. Study was considered successful if patient was able to tolerate PAP during titration and also if adherent to PAP at follow up. Results 48 studies met the criteria for SNPSG, with 60% of SNPSG being emergency SNPSG with AHI&amp;gt;30. Our cohort’s age ranged from 2–18 years (median age 8 years); 33 were males. Majority of the emergency SNPSG were in younger children (80% &amp;lt; 5 years), 75% of them continued to use PAP (mostly CPAP) until T &amp; A with wait time being more than 3 months. Average wait time for T &amp; A was 4 months. 25% of patients continued to use PAP following T &amp; A as residual AHI was &amp;gt;10/hour. 98% of the patients were able to tolerate PAP during titration section with restoration of sleep architecture including REM with reduction in AHI, arousals and improved sleep efficiency. Bilevel PAP was used in 10% of patients in mostly planned SNPSG. Conclusion SNPSG can be implemented with fair degree of success during initial PSG with PAP used until T &amp; A is performed. Planned SNPSG are also useful with residual severe OSA eliminating need for subsequent titration study. When indicated, 75% of our cohort continued to use PAP with fair adherence (&amp;gt;70% nightly use) following SNPSG. Support (if any):

846 Pulmonary Arterial Hypertension as a Sequela of Untreated Obstructive Sleep Apnea in a Patient with Prader-Willi Syndrome

Abstract Introduction Prader-Willi Syndrome (PWS) is a complex neurogenetic disorder characterized by hypotonia, behavioral problems, endocrinopathies, sleep and respiratory abnormalities. Morbidity and mortality in the PWS population is attributable to obesity, cardiovascular problems, and sleep apnea. We report a patient with PWS presenting with pulmonary arterial hypertension (PAH) due to untreated obstructive sleep apnea (OSA). Report of case(s) Our patient is a 17-year-old female with a past medical history of PWS, scoliosis, obesity (BMI 52.46), hypogonadotropic hypogonadism, and type II diabetes. Baseline echocardiogram (ECHO) performed at age 9 revealed an estimated right ventricular systolic pressure (eRVSP) of 32mmHg above right atrial pressure (RAP), tricuspid regurgitation (TR) at 2.8 m/sec with no interventricular septal flattening (IVSF) and right ventricle (RV) systolic dysfunction suggestive of mild PAH. Given significant scoliosis the patient did not qualify for growth hormone therapy. She underwent a polysomnogram (PSG) at age 14 showing severe obstructive sleep apnea; apnea-hypopnea index (AHI) of 22.6 (oAHI 22.6). Patient was subsequently lost to follow up until presenting in acute respiratory failure at age 17. She required endotracheal intubation and was extubated to bilevel PAP (BPAP) with inability to wean off BPAP. At that time an ECHO revealed eRVSP of 55 mmHg above RAP, IVSF, TR at 3.7 m/sec, and RV systolic dysfunction suggestive of moderate to severe PAH and developing right sided heart failure. A PAP titration PSG during this admission revealed hypoxemia with oxygen saturation less than 90% (O2 nadir 70%) 12.6% of total sleep time (TST) and hypoventilation (transcutaneous CO2 max of 57 mmHg with an elevation above 50 mmHg for 100% of TST). Using an inspiratory PAP (IPAP) of 24 cmH2O and expiratory PAP (EPAP) of 14 cmH20 with supplemental O2 of 4LPM the respiratory events and hypoxemia resolved but there was persistence of hypoventilation. Tadalafil was initiated for PAH and BPAP therapy for OSA. Follow up visits 4- and 8-weeks post discharge shows improving PAH (TR 3.6 m/sec, eRSVP 52 mmHg, and mild IVSF) due to BPAP and tadalafil therapies. Conclusion This case highlights the importance of treating OSA in patients with PWS to prevent cardiorespiratory complications and reduce morbidity and mortality. Support (if any) None

Drug-Induced Sleep Endoscopy and Hypoglossal Nerve Stimulation Outcomes: A Multicenter Cohort Study.

To determine the association between findings of blinded reviews of preoperative drug-induced sleep endoscopy (DISE) and outcomes of hypoglossal nerve stimulation (HNS) for obstructive sleep apnea (OSA). Cohort study. A retrospective, multicenter cohort study of 343 adults who underwent treatment of OSA with HNS from 10 academic medical centers was performed. Preoperative DISE videos were scored by four blinded reviewers using the VOTE Classification and evaluation of a possible primary structure contributing to airway obstruction. Consensus DISE findings were examined for an association with surgical outcomes based on therapy titration polysomnogram (tPSG). Treatment response was defined by a decrease of ≥50% in the apnea-hypopnea index (AHI) to <15 events/hour. Study participants (76% male, 60.4 ± 11.0 years old) had a body mass index of 29.2 ± 3.6 kg/m2 . AHI decreased (35.6 ± 15.2 to 11.0 ± 14.1 events/hour; P < .001) on the tPSG, with a 72.6% response rate. Complete palate obstruction (vs. none) was associated with the greatest difference in AHI improvement (-26.8 ± 14.9 vs. -19.2 ± 12.8, P=.02). Complete (vs. partial/none) tongue-related obstruction was associated with increased odds of treatment response (78% vs. 68%, P=.043). Complete (vs. partial/none) oropharyngeal lateral wall-related obstruction was associated with lower odds of surgical response (58% vs. 74%, P=.042). The DISE finding of primary tongue contribution to airway obstruction was associated with better outcomes, whereas the opposite was true for the oropharyngeal lateral walls. This study suggests that the role for DISE in counseling candidates for HNS extends beyond solely for excluding complete concentric collapse related to the velum. 3 Laryngoscope, 131:1676-1682, 2021.

1229 Management of Severe Sleep Related Disordered Breathing in a Pediatric Case of Vagal Nerve Stimulation

Abstract Introduction Vagal nerve stimulator (VNS) can be an effective treatment for refractory epilepsy but can lead to sleep related disordered breathing in the form of obstructive and central sleep apnea. We describe a pediatric case with VNS developing severe obstructive sleep apnea (OSA) and the course of management. Report of Case A 10-year-old boy with history of cerebral palsy, medically intractable epilepsy secondary to Lennox-Gastaut syndrome, and noted improvement in seizure frequency with VNS placement, presented to the pediatric sleep clinic with concern for sleep disordered breathing in the setting of snoring and witnessed gasping at night. The polysomnogram (PSG) showed severe OSA with apnea/hypopnea index (AHI) of 21.8 events/hour and associated hypoxemia. He subsequently underwent adenotonsillectomy. Post procedural PSG demonstrated persistent severe OSA. The obstructive events had rhythmicity temporally coincident with the VNS cycling. Subsequent PSG, after turning VNS off, showed a reduction in AHI to 11 events/hour without hypoxemia. Positive airway pressure (PAP) was initiated during this PSG, however titration was rendered unsuccessful due to VNS activation. A final titration PSG was performed with optimal resolution of OSA with VNS turned off. Since the patient did not have nocturnal seizures, it was recommended to turn the VNS off at nighttime with CPAP use. Patient was noted to have less sleep disruptions at night and more alertness during the day. Conclusion This case poses a challenging situation where patient’s epilepsy responded to VNS but the device contributed to OSA and affected PAP titration. One strategy to improve OSA in such cases is to change VNS parameters at the risk of changing stimulation settings effective for seizure control. Turning VNS off during sleep provided a simpler solution while ensuring effective treatment. Thus, clinicians should be vigilant about concomitant OSA treatment in the setting of vagal nerve stimulation, which can improve quality of life.

0508 SLEEP APNEA AND ATRIAL FIBRILLATION - PHENOTYPE AND OUTCOMES

Sleep apnea, especially central (CSA), is associated with atrial fibrillation (AF). We hypothesized that AF patients are at high risk for treatment-emergent/complex apnea, and residual disease during long-term therapy with positive airway pressure. The sleep laboratory database at the Beth Israel Deaconess Medical center and affiliated services was queried, focusing on patients with AF, to extract polysomnographic information. The BIDMC Online Medical Records was used to collect co-morbid information. Residual apnea and related information was extracted from the EnocreAnywhere database; at the BIDMC, tracking is life-long, enabling assessment of outcomes beyond 6 months. Three hundred and eighteen patients had complete clinical/polysomnographic data, and 212 were reviewed in EncoreAnywhere. Split night was 31%. Summary statistics: age 68.3 ± 11.1 years, 69.1% male, BMI 33.6 ± 8 Kg/M2, ejection fraction 53.5 ± 10.8 (22% less than 50%), hypertension 68.6%. Baseline total sleep time (TST): 181.4 ± 116.3 minutes, sleep efficiency 62.9 ± 19.3 %, N1 24.3 ± 21.5% TST, N3: 9.7 ± 13.9 % TST, RDI: 39.4 ± 21.7, AHI4% 8.2 ± 11.9, minimum saturation 81.8 ± 10 %. Titration data: TST: 242 ± 98.9 minutes, sleep efficiency 66.9 ± 19.8 %, N1: 18 ± 15.2 %, RDI 27 ± 21.6, AHI4% 5 ± 8.5, minimum saturation 85.4 ± 6.9 %. CSA was noted in 4% on baseline, and treatment-emergent/complex apnea in 30%. The mean duration of use of positive airway pressure (93% continuous) was 21 ± 3 months, mean use 4.1 ± 2.1 hours. Residual AHI-flow was 11.6 ± 7.8 / hour of use, and periodic breathing of at least 10 minutes duration on visual waveforms inspection in 76.4 %. Patients with AF have highly fragmented sleep during diagnostic and titration polysomnograms. Complex sleep apnea is common, as is residual sleep apnea and periodic breathing on waveforms. This likely reflects persistently elevated loop gain. AF patients with sleep apnea are at high risk for reduced treatment effectiveness, and may require a dedicated phenotype-driven clinical pathway for optimal management. Beth Israel Deaconess Medical Center Chief Academic Officer’s Innovation Grant.

Factors Associated with Changes in Invasive and Noninvasive Positive Airway Pressure Therapy Settings during Pediatric Polysomnograms.

Our aim was to identify clinical predictors associated with changes in settings for pediatric invasive and noninvasive positive airway pressure therapy, which could help inform the allocation of limited polysomnogram (PSG) resources. A retrospective review was conducted in children who underwent one or more PSGs for technology titration. Children were included if they were using continuous positive airway pressure (CPAP) therapy, bilevel positive airway pressure (BPAP) therapy, or invasive positive pressure ventilation (IPPV) the night of the PSG. The primary outcome measure for the study were predictors of change in settings during IPPV, CPAP, and BPAP titration studies. During the study period, 274 children using CPAP, BPAP, or IPPV underwent one or more titration PSGs. The mean (standard deviation [SD]) age of the children at the time of the first titration PSG was 10.52 (5.11) y. Fifty percent (n = 136) of the study participants were male. Most patients underwent BPAP titration studies (n = 166), followed by CPAP (n = 83) and then IPPV (n = 25). A total of 623 technology titration PSGs were completed. Reason for respiratory technology, type of respiratory technology, and time between ventilation initiation and the PSG were significant predictors of a change in settings in the multivariable regression model. Children were more likely to have a change in their technology settings during a PSG if there was a shorter period of time from the original technology initiation, if they were using BPAP (as compared to CPAP or IPPV) and/or if they had a primary central nervous system or musculoskeletal diagnosis.

Financial Analysis of an Intensive Pediatric Continuous Positive Airway Pressure Program.

Continuous positive airway pressure (CPAP) is effective in treating obstructive sleep apnea in children, but adherence to therapy is low. Our center created an intensive program that aimed to improve adherence. Our objective was to estimate the program's efficacy, cost, revenue and break-even point in a generalizable manner relative to a standard approach. The intensive program included device consignment, behavioral psychology counseling, and follow-up telephone calls. Economic modeling considered the costs, revenue and break-even point. Costs were derived from national salary reports and the Pediatric Health Information System. The 2015 Medicare reimbursement schedule provided revenue estimates. Prior to the intensive CPAP program, only 67.6% of 244 patients initially prescribed CPAP appeared for follow-up visits and only 38.1% had titration polysomnograms. In contrast, 81.4% of 275 patients in the intensive program appeared for follow-up visits (p < .001) and 83.6% had titration polysomnograms (p < .001). Medicare reimbursement levels would be insufficient to cover the estimated costs of the intensive program; break-even points would need to be 1.29-2.08 times higher to cover the costs. An intensive CPAP program leads to substantially higher follow-up and CPAP titration rates, but costs are higher. While affordable at our institution due to the local payer mix and revenue, Medicare reimbursement levels would not cover estimated costs. This study highlights the need for enhanced funding for pediatric CPAP programs, due to the special needs of this population and the long-term health risks of suboptimally treated obstructive sleep apnea.

Claustrophobic tendencies and continuous positive airway pressure therapy non-adherence in adults with obstructive sleep apnea

Objectives(1) Determine claustrophobia frequency in adults with obstructive sleep apnea (OSA) after first CPAP night; (2) determine if claustrophobia influences CPAP non-adherence. BackgroundClaustrophobia is common among CPAP-treated OSA adults yet few studies have examined the problem. MethodsSecondary analysis of prospective, longitudinal study of OSA adults (n = 97). CPAP-Adapted Fear and Avoidance Scale (CPAP-FAAS) collected immediately after CPAP titration polysomnogram. Primary outcome: objective CPAP use at 1week and 1month. ResultsSixty-three percent had claustrophobic tendencies. Females had higher CPAP-FAAS scores than males. FAAS ≥25, positive score for claustrophobic tendencies, was influential on CPAP non-adherence at 1week (aOR = 5.53, 95% CI 1.04, 29.24, p = 0.04) and less CPAP use at 1month (aOR = 5.06, 95% CI 1.48, 17.37, p = 0.01) when adjusted for body mass index and CPAP mask style. ConclusionClaustrophobia is prevalent among CPAP-treated OSA adults and influences short-term and longer-term CPAP non-adherence. Interventions are needed to address this treatment-related barrier.

Risk assessment for CPAP nonadherence in adults with newly diagnosed obstructive sleep apnea: preliminary testing of the Index for Nonadherence to PAP (I-NAP)

Identification of risk for continuous positive airway pressure therapy (CPAP) nonadherence prior to home treatment is an opportunity to deliver targeted adherence interventions. Study objectives included the following: (1) test a risk screening questionnaire to prospectively identify CPAP nonadherence risk among adults with newly diagnosed obstructive sleep apnea (OSA), (2) reduce the questionnaire to a minimum item set that effectively identifies 1-month CPAP nonadherence, and (3) examine the diagnostic utility of the screening index. A prospective, longitudinal study at two clinical sleep centers in the USA included adults with newly diagnosed OSA (n=97; AHI≥5 events/h) by polysomnogram (PSG) consecutively recruited to participate. After baseline participant and OSA characteristics were collected, a risk screening questionnaire was administered immediately following CPAP titration polysomnogram. One-month objective CPAP use was collected. Predominantly, white (87%), males (55%), and females (45%) with obesity (BMI 38.3 kg/m2; SD 9.3) and severe OSA (AHI 36.8; SD 19.7) were included. One-month CPAP use was 4.25 h/night (SD 2.35). Nineteen questionnaire items (I-NAP) reliably identified nonadherers defined at <4 h/night CPAP use (Wald X2[8]=34.67, p<0.0001) with ROC AUC 0.83 (95% CI 0.74-0.91). Optimal score cut point for the I-NAP screening questionnaire were determined to maximize sensitivity (87%) while maintaining specificity>60% (63%). A risk screening questionnaire employed immediately after titration PSG may reliably identify CPAP nonadherers and permit the delivery of targeted interventions to prevent or reduce nonadherence. This novel approach may enhance cost-effectiveness of care and permit appropriate allocation of resources for CPAP adherence.

Low Frequency Filtering of Nasal Pressure Channel Causes Loss of Flow Limitation

ABSTRACT.Study objectives: The objective of this clinical vignette is to explore whether changes in low filter settings for respiratory waveforms have a clinically significant effect on patient management of obstructive sleep apnea (OSA). Design: This is a case report. Methods: We collected data from a continuous positive airway pressure (CPAP) titration polysomnogram (PSG) performed in our university based sleep laboratory. We reviewed the flow signal using low frequency filter settings of 0.0. 0.1, 0.3, and 0.5 Hz. Results: We noted that a change in the low frequency filter for respiratory flow caused a change in the appearance of an otherwise flattened waveform indicating flow limitation to no longer appear flat. Conclusion: We noted that indiscriminate use of the low frequency filter for nasal pressure and flow estimate channels may lead to greater difficulty recognizing respiratory flow limitation.

Continuous positive airway pressure requirements in patients with tetraplegia and obstructive sleep apnoea

Clinic-based retrospective case-control study. To compare continuous positive airway pressure (CPAP) requirements between patients with tetraplegia and able-bodied patients with obstructive sleep apnoea (OSA). Melbourne, Australia. Diagnostic and CPAP titration polysomnograms of 219 able-bodied, and 25 patients with tetraplegia and OSA were compared for apnoea hypopnoea index (AHI) and CPAP levels required to effectively treat OSA. Demographics and body mass index (BMI) were obtained for each patient. ASIA score and injury date were obtained for patients with tetraplegia. There was no significant difference in AHI (P=0.102) between the two groups; however, able-bodied patients were significantly older (P=0.003), required significantly higher levels of CPAP to control their OSA (P<0.001) and had higher BMIs (P=0.009) than patients with tetraplegia. In the tetraplegia group, there was no significant correlation between AHI and effective CPAP (r=0.022, P=0.92) or between AHI and BMI (r=-0.196, P=0.35). There was a significant correlation between effective CPAP and BMI (r=0.411, P=0.041). Among able-bodied patients, over two-thirds (68.8%) required 10-16 cm H(2)0 to control their OSA and nearly one-third required over 16 cm H(2)0. In contrast, over two-thirds (68.8%) in the tetraplegia group required less than 10 cm H(2)0 of CPAP to control their OSA. This retrospective study suggests that OSA patients with tetraplegia require significantly less CPAP to treat their OSA at any given AHI than those who are able-bodied. This suggests that additional unknown factors may contribute to the high prevalence of OSA in tetraplegia.

The Prevalence and Natural History of Complex Sleep Apnea

Central sleep apnea (CSA) may occasionally occur in patients with obstructive sleep apnea during titration with a continuous positive airway pressure (CPAP) device. To determine the prevalence and the natural history of CPAP-emergent CSA. This is a retrospective study of 1286 patients with a diagnosis of OSAwho underwent titration with a positive airway device during a 1-year period. Patients were seen in consultation and underwent full-night attended polysomnography followed by full-night attended CPAP titration. Four weeks after CPAP therapy, patients returned to the clinic for follow-up, and objective adherence to CPAP was recorded. In patients who had CSA on CPAP, a second full-night attended CPAP titration was recommended. Eighty-four of the 1286 patients developed a central apnea index (CAI) of 5 or greater per hour while on CPAP. The incidence of CSA varied from 3% to 10% monthly, with an overall incidence of 6.5%. Forty-two of the 84 patients returned for a second CPAP titration. In 33 patients, CSA was eliminated. In each of the remaining 9 patients, the CAI remained at 5 or greater per hour, with an average of 13 per hour. These patients characteristically had the most severe OSA, and 5 had a CAI of 5 or more per hour at baseline. Two of the 9 patients were on opioids In this large retrospective study of 1286 patients with a diagnosis of OSA, 6.5% had CPAP-emergent or persistent CSA. However, CPAP-emergent CSA was generally transitory and was eliminated within 8 weeks after CPAP therapy. The prevalence of CPAP-persistent CSA was about 1.5%. Severity of OSA, a CAI of 5 or greater per hour, and use of opioids were potential risk factors.

Effect of a Titration Polysomnogram on Treatment Success with a Mandibular Repositioning Appliance

Mandibular repositioning appliance (MRA) therapy is a treatment option for patients with mild to moderate sleep apnea and for patients who do not tolerate continuous positive airway pressure. Titration of MRAs consists of sequential mandibular advancement guided by symptom improvement. The goal of the study was to determine if patients with an elevated apnea hypopnea index (AHI), despite the use of a subjectively optimized MRA, could achieve better results with additional titration during polysomnography (PSG). Patients were enrolled if they had an AHI > or = 15/h and were referred for MRA therapy. The MRAwas advanced until symptoms improved. During the PSG, the technologist monitored the patient's sleep and increased mandibular protrusion until the AHI was improved. There was a significant improvement in AHI, minimum oxygen saturation, and total sleep time with the MRA before further advancement. At the final PSG, 65.2% of patients had an AHI < or = 10 associated with at least a 50% reduction in AHI. The incomplete responders had their appliance further titrated, and this improved the results of MRA therapy by 30.4% to a total success rate of 95.6%. This study shows that it is possible to improve the results of MRA therapy by further advancing the appliance during a titration PSG in patients with an incomplete response. The titration night improved the results of the usual clinical advancement of the MRA with substantially more patients achieving a successful outcome.

Irregular Respiration as a Marker of Wakefulness During Titration of CPAP

Regularity of respiration is characteristic of stable sleep without sleep disordered breathing. Appearance of respiratory irregularity may indicate onset of wakefulness. The present study examines whether one can detect transitions from sleep to wakefulness using only the CPAP flow signal and automate this recognition. Prospective study with blinded analysis Sleep disorder center, academic institution. 74 subjects with obstructive sleep apnealhypopnea syndrome (OSAHS) INTERVENTIONS: n/a. 74 CPAP titration polysomnograms in patients with OSAHS were examined. First we visually identified characteristic patterns of ventilatory irregularity on the airflow signal and tested their relation to conventional detection of EEG defined wake or arousal. To automate recognition of sleep-wake transitions we then developed an artificial neural network (ANN) whose inputs were parameters derived exclusively from the airflow signal. This ANN was trained to identify the visually detected ventilatory irregularities. Finally, we prospectively determined the accuracy of the ANN detection of wake or arousal against EEG sleep/wake transitions. A visually identified irregular respiratory pattern (IrREG) was highly predictive of appearance of EEG wakefulness (Positive Predictive Value [PPV] = 0.89 to 0.98 across subjects). Furthermore, we were able to automate identification of this irregularity with an ANN which was highly predictive for wakefulness by EEG (PPV 0.66 to 0.86). Despite not detecting all wakefulness, the high positive predictive value suggests that analysis of the respiration signal alone may be a useful indicator of CNS state with potential utility in the control of CPAP in OSAHS. The present study demonstrates the feasibility of automating the detection of IrREG.

Variables affecting the change in systemic blood pressure in response to nasal CPAP in obstructive sleep apnea patients

We hypothesized that an improvement in systemic blood pressure (BP) during continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea (OSA) would be related to severity of hypertension (HTN), morphometric parameters such as body mass index, and level of CPAP adherence. We tested this hypothesis with a retrospective review of 85 consecutive OSA patients who had completed diagnostic and CPAP titration polysomnograms and were equipped with a CPAP-adherence monitoring system for a minimum of 1 month of observation. Sphygmomanometer-obtained BP readings were compared at baseline and after 4-6 weeks of CPAP therapy. Presentation BP was significantly and strongly associated with the change in BP seen with treatment. Those with an elevated systolic and diastolic BP and those with an elevation of either systolic or diastolic BP showed a significant fall in BP on CPAP. Those with a BP below the hypertensive range of 140/90 on presentation did not have a significant drop in BP with CPAP. There were no significant changes in systolic, diastolic, or mean BP when patients were categorized by the severity of HTN, as determined by the number of antihypertensive medications prescribed or if they were categorized by the degree of CPAP adherence, objectively determined by the average use of more or less than 4 h/night. We conclude that HTN at initial presentation is among the most important indicators of potential benefit of CPAP administration on BP.

Improvement of obstructive sleep apnea after radiation therapy of vocal cord carcinoma

A 52-year-old gentleman presented to the sleep clinic with a history of witnessed episodes of apnea, loud snoring, and moderate subjective sleepiness (Epworth Sleepiness Scale (ESS), 10). The patient reported an average time in bed of 6.5 h per night. Physical exam revealed a weight of 206 lbs, a body mass index of 30, a Mallampati class of 2 and tonsils class 2. The diagnostic polysomnogram showed moderate obstructive sleep apnea (apnzea–hypopnea index (AHI) = 24). The patient was prescribed a continuous positive airway pressure (CPAP) device at 13 cm H2O of pressure based on a titration polysomnogram. On one-month follow-up, the patient had very low adherence to CPAP treatment and subsequently stopped using it. The patient presented to his primary physician with a new onset of intermittent hoarseness four months after his initial sleep evaluation. The patient was prescribed antibiotics and referred to an otolaryngologist, and was diagnosed with an invasive squamous cell carcinoma of the left true vocal cord (T2, N0, M0) (Fig. 1). The patient underwent an excisional biopsy and radiation therapy with 6075 centigray.