Fabiola Schorr

Upper airway collapsibility is associated with obesity and hyoid position.

STUDY OBJECTIVES Upper airway anatomy plays a major role in obstructive sleep apnea (OSA) pathogenesis. An inferiorly displaced hyoid as measured by the mandibular plane to hyoid distance (MPH) has been consistently associated with OSA. The hyoid is also a common landmark for pharyngeal length, upper airway volume, and tongue base. Tongue dimensions, pharyngeal length, and obesity are associated with OSA severity, although the link between these anatomical variables and pharyngeal collapsibility is less well known. We hypothesized that obesity as measured by body mass index (BMI), neck and waist circumferences, and variables associated with hyoid position (pharyngeal length, upper airway volume, and tongue dimensions) would be associated with passive pharyngeal critical closing pressure (Pcrit). DESIGN Cross-sectional. SETTING Academic hospital. PATIENTS 34 Japanese-Brazilian males age 21 to 70 y. INTERVENTIONS N/A. MEASUREMENTS AND RESULTS We performed computed tomography scans of the upper airway, overnight polysomnography, and Pcrit measurements in all subjects. On average, subjects were overweight (BMI = 28 ± 4 kg/m(2)) and OSA was moderately severe (apnea-hypopnea index = 29 [13-51], range 1-90 events/h). Factor analysis identified two factors among the studied variables: obesity (extracted from BMI, neck and waist circumferences) and hyoid position (MPH, pharyngeal length, tongue length, tongue volume, and upper airway volume). Both obesity and hyoid position correlated with Pcrit (r = 0.470 and 0.630, respectively) (P < 0.01). In addition, tongue volume, tongue length, pharyngeal length, and MPH correlated with waist and neck circumferences (P < 0.05). CONCLUSIONS Pharyngeal critical closing pressure is associated with obesity and hyoid position. Tongue dimensions, pharyngeal length, and the mandibular plane to hyoid distance are associated with obesity variables. These findings provide novel insight into the potential factors mediating upper airway collapse in obstructive sleep apnea.

Continuous positive airway pressure delivered by oronasal mask may not be effective for obstructive sleep apnoea

To the Editors: Continuous positive airway pressure (CPAP) is considered the gold standard treatment for patients with moderate to severe obstructive sleep apnoea (OSA). The treatment of OSA with CPAP was first conceptualised using a nasal-only interface because the pressure delivered through the nose would be transmitted to the back of the upper airway and would push the palate anteriorly [1]. Since the first description, the CPAP industry has developed a large number of different interfaces in order to improve patient comfort and adherence to treatment. Patients with OSA frequently present nasal obstruction and oronasal interfaces may be used to deliver CPAP. Nasal and oronasal masks are often used interchangeably and the choice of CPAP delivery interface for OSA therapy remains largely based on clinical experience. However, patients with OSA on oronasal mask are less adherent to CPAP for reasons that are not completely understood [2]. One recent randomised trial [3] and a preliminary report [4] suggest that the effectiveness of CPAP for treating OSA is variable when delivered by an oronasal interface. We describe a well-documented patient in whom CPAP was not effective when an oronasal mask was used due to the posterior displacement of the tongue. A 69-yr-old Japanese–Brazilian, body mass index 26.1 kg·m−2, presented to the outpatient sleep clinic complaining of typical symptoms suggestive of OSA, including loud snoring, witnessed apnoeas and excessive daytime sleepiness. The patient had a positive medical history of systemic hypertension and diabetes mellitus. A standard overnight polysomnography (Alice 5; Philips Respironics, Murrysville, PA, USA) confirmed severe OSA, with apnoea-hypopnoea index (AHI) 76 events per h and lowest oxygen saturation 58%. An in-laboratory manual CPAP titration study was performed with an oronasal mask because of reported oral breathing during sleep. CPAP was …

Sleep and glycemic control in type 1 diabetes

OBJECTIVE Our aim in the present study was to elucidate how type 1 diabetes mellitus (T1DM) and sleep parameters interact, which was rarely evaluated up to the moment. MATERIALS AND METHODS Eighteen T1DM subjects without chronic complications, and 9 control subjects, matched for age and BMI, were studied. The following instruments used to evaluate sleep: the Epworth Sleepiness Scale, sleep diaries, actimeters, and polysomnography in a Sleep Lab. Glycemic control in T1DM individuals was evaluated through: A1C, home fingertip glucometer for 10 days (concomitant with the sleep diary and actimeter), and CGM or concomitant with continuous glucose monitoring (during the polysomnography night). RESULTS Comparing with the control group, individuals with diabetes presented more pronounced sleep extension from weekdays to weekends than control subjects (p = 0.0303). Among T1DM, glycemic variability (SD) was positively correlated with sleep latency (r = 0.6525, p = 0.0033); full awakening index and arousal index were positively correlated with A1C (r = 0.6544, p = 0.0081; and r = 0.5680, p = 0.0272, respectively); and mean glycemia values were negatively correlated with sleep quality in T1DM individuals with better glycemic control (mean glycemia < 154 mg/dL). CONCLUSION Our results support the hypothesis of an interaction between sleep parameters and T1DM, where the glycemic control plays an important role. More studies are needed to unveil the mechanisms behind this interaction, which may allow, in the future, clinicians and educators to consider sleep in the effort of regulating glycemic control.

Different Craniofacial Characteristics Predict Upper Airway Collapsibility in Japanese-Brazilian and White Men

BACKGROUND OSA pathogenesis is complex and may vary according to ethnicity. The anatomic component predisposing to OSA is the result of the interaction between bony structure and upper airway soft tissues and can be assessed using passive critical closing pressure (Pcrit). We hypothesized that Japanese-Brazilians and whites present different predictors of upper airway collapsibility, suggesting different causal pathways to developing OSA in these two groups. METHODS Male Japanese-Brazilians (n = 39) and whites (n = 39) matched for age and OSA severity were evaluated by full polysomnography, Pcrit, and upper airway and abdomen CT scans for determination of upper airway anatomy and abdominal fat, respectively. RESULTS Pcrit was similar between the Japanese-Brazilians and the whites (-1.0 ± 3.3 cm H2O vs -0.4 ± 3.1 cm H2O, P = .325). The Japanese-Brazilians presented smaller upper airway bony dimensions (cranial base, maxillary, and mandibular lengths), whereas the whites presented larger upper airway soft tissue (tongue length and volume) and a greater imbalance between tongue and mandible (tongue/mandibular volume ratio). The cranial base angle was associated with Pcrit only among the Japanese-Brazilians (r = -0.535, P < .01). The tongue/mandibular volume ratio was associated with Pcrit only among the whites (r = 0.460, P < .01). Obesity-related variables (visceral fat, BMI, and neck and waist circumferences) showed a similar correlation with Pcrit in the Japanese-Brazilians and the whites. CONCLUSIONS Japanese-Brazilians and whites present different predictors of upper airway collapsibility. Although craniofacial bony restriction influenced Pcrit only in the Japanese-Brazilians, an anatomic imbalance between tongue and mandible volume influenced Pcrit among the whites. These findings may have therapeutic implications regarding how to improve the anatomic predisposition to OSA across ethnicities.

Type 1 diabetes mellitus and its glycemic control affect sleep

Materials and methods Eighteen non-obese adults with T1D (8 males, age=26.3±5.1), without chronic complications were studied. The following instruments were used during ten consecutive days: sleep diaries (with Visual Analogue Scales for rating sleep quality), actimeters, and a home fingertip glucometer (6.41±1.5 tests a day). The analysis was made using fitted inflated beta regression models with GAMLSS for the response variable sleep quality rate (SQR). Subject-level covariables in this dataset included: number of hyperglycemia and hypoglycemia episodes in the previous day, number of awakenings during the night, morning awakening type (spontaneous or not), sleep rate (total sleep time in min divided by 1440), and the corresponding interactions. Results The SQR was negatively associated with the sleep rate (p<0.001), and positively associated with spontaneous awakening (p=0.042). The relationships between the other variables with SQR were the following: the SQR rises with the increase of both, hypoglycemic events and sleep rate (p=0.002). On the other hand, when the hypoglycemic or hyperglycemic events are associated with non-spontaneous awakening, the SQR decreases (p=0.02 for both glycemic conditions). However, the SQR increases when both the number of hyperglycemia and the number of night awakenings increase (p=0.01).