Airflow Shape Is Associated With the Pharyngeal Structure Causing OSA.

BACKGROUND: OSA results from the collapse of different pharyngeal structures (soft palate, tongue, lateral walls, and epiglottis). The structure involved in collapse has been shown to impact non-CPAP OSA treatment. Different inspiratory airflow shapes are also observed among patients with OSA. We hypothesized that inspiratory flow shape reflects the underlying pharyngeal structure involved in airway collapse. METHODS: Subjects with OSA were studied with a pediatric endoscope and simultaneous nasal flow and pharyngeal pressure recordings during natural sleep. The mechanism causing collapse was classified as tongue-related, isolated palatal, lateral walls, or epiglottis. Flow shape was classified according to the degree of negative effort dependence (NED), defined as the percent reduction in inspiratory flow from peak to plateau. RESULTS: Thirty-one subjects with OSA (mean apnea-hypopnea index score ± SD, 54 ± 27 events/h) who were 50 ± 9 years of age were studied. NED was associated with the structure causing collapse (P < .001). Tongue-related obstruction (n = 13) was associated with a small amount of NED (median, 19; interquartile range [IQR], 14%-25%). Moderate NED was found among subjects with isolated palatal collapse (median, 45; IQR, 39%-52%; n = 8) and lateral wall collapse (median, 50; IQR, 44%-64%; n = 8). The epiglottis was associated with severe NED (median, 89; IQR, 78%-91%) and abrupt discontinuities in inspiratory flow (n = 9). CONCLUSIONS: Inspiratory flow shape is influenced by the pharyngeal structure causing collapse. Flow shape analysis may be used as a noninvasive tool to help determine the pharyngeal structure causing collapse.

Critical evaluation of screening questionnaires for obstructive sleep apnea in patients undergoing coronary artery bypass grafting and abdominal surgery.

BACKGROUND: Obstructive sleep apnea (OSA) is an independent risk factor for complications after surgery. However, OSA remains largely under recognized, and questionnaires designed to detect OSA have shown inconsistent results. Patients with cardiovascular diseases may not present with the typical symptoms of OSA. We therefore sought to compare the performance of screening questionnaires of patients referred for coronary artery bypass grafting (CABG) versus abdominal surgery (Abd surgery). METHODS: We studied 40 consecutive patients referred for CABG [29 men; age 56 ± 7 years; body mass index (BMI) 30 ± 4 kg/m(2)], and 41 referred to Abd Surgery matched for age, gender, and BMI (28 men; age 56 ± 8 years; BMI 29 ± 5 kg/m(2)). All patients were evaluated with validated questionnaires to predict OSA (STOP-Bang and Berlin), Epworth sleepiness scale (ESS) and full overnight polysomnography. RESULTS: The prevalence of OSA (apnea-hypopnea index ≥15 events/hour) in the CABG and Abd surgery groups was similar (52 and 41 %, respectively, p = 0.32). The Berlin questionnaire showed similar sensitivity (67 vs. 82 %, p = 0.17) but lower specificity in the CABG group (26 vs. 62 %, p = 0.02). The STOP-BANG questionnaire had a high sensitivity (90 vs. 94 %, p = 0.42) but low specificity (5 vs. 13 %, p = 0.25) in the CABG and Abd surgery groups, respectively. Patients referred for CABG slept less (323 [285-376] vs. 378 [308-415] minutes, p = 0.04) but had lower levels of daytime sleepiness than Abd surgery patients had (ESS, 6 ± 4 vs. 9 ± 5; p = 0.01, respectively). CONCLUSIONS: Presenting clinical characteristics of OSA are modulated by the population evaluated and may affect the performance of screening questionnaires.

Lack of reliable clinical predictors to identify obstructive sleep apnea in patients with hypertrophic cardiomyopathy

OBJECTIVE: Obstructive sleep apnea is common among patients with hypertrophic cardiomyopathy and may contribute to poor cardiovascular outcomes. However, obstructive sleep apnea is largely unrecognized in this population. We sought to identify the clinical predictors of obstructive sleep apnea among patients with hypertrophic cardiomyopathy. METHODS: Consecutive patients with hypertrophic cardiomyopathy were recruited from a tertiary University Hospital and were evaluated using validated sleep questionnaires (Berlin and Epworth) and overnight portable monitoring. Ninety patients (males, 51%; age, 46±15 years; body mass index, 26.6±4.9 kg/m2) were included, and obstructive sleep apnea (respiratory disturbance index ≥15 events/h) was present in 37 patients (41%). RESULTS: Compared with the patients without obstructive sleep apnea, patients with obstructive sleep apnea were older and had higher body mass index, larger waist circumference, larger neck circumference, and higher prevalence of atrial fibrillation. Excessive daytime sleepiness (Epworth scale) was low and similar in the patients with and without obstructive sleep apnea, respectively. The only predictors of obstructive sleep apnea (using a logistic regression analysis) were age ≥45 years (odds ratio [OR], 4.46; 95% confidence interval [CI 95%], 1.47-13.54; p = 0.008) and the presence of atrial fibrillation [OR, 5.37; CI 95%, 1.43-20.12; p = 0.013]. CONCLUSION: Consistent clinical predictors of obstructive sleep apnea are lacking for patients with hypertrophic cardiomyopathy, which suggests that objective sleep evaluations should be considered in this population, particularly among elderly patients with atrial fibrillation. .

Cheyne-Stokes respiration in patients with congestive heart failure: causes and consequences

A respiração de Cheyne-Stokes é uma forma de respiração periódica na qual apnéias e hipopnéias se alternam com períodos de hiperpnéias que apresentam um padrão crescendo e decrescendo de volume corrente. Esta revisão enfoca as causa e conseqüências da respiração de Cheyne- Stokes em pacientes com insuficiência cardíaca congestiva na qual a prevalência é extremamente alta e varia entre 30 a 50%. Vários fatores foram implicados na gênese da respiração de Cheyne-Stokes, incluindo baixo debito cardíaco e hipoxia recorrente. Hiperventilacão e baixos níveis de CO2 arterial (PaCO2), que quando abaixo do limiar de apnéia desencadeiam apnéia central são os mecanismos fisiopatológicos chave na gênese da respiração de Cheyne-Stokes. Hiperventilação está associada com congestão pulmonar, e a respiração de Cheyne-Stokes tem uma tendência maior de ocorrer durante o sono, quando o centro respiratório é dependente principalmente do controle químico. A respiração de Cheyne-Stokes está associada a quedas recorrentes da saturação de oxigênio e ao despertar do sono, com oscilações recorrentes na freqüência cardíaca, pressão arterial, aumento da atividade simpática e risco aumentado de taquicardia ventricular. A respiração de Cheyne-Stokes é um marcador independente de mau prognostico e provavelmente participa de um ciclo vicioso que contribui para a deterioração cardíaca.