Upper airway anatomical balance contributes to optimal continuous positive airway pressure for Japanese patients with obstructive sleep apnea syndrome

Optimal positive airway pressure requirement and polysomnography indices of obstructive sleep apnea severity in the Saudi population

CONTEXT

Positive airway pressure (PAP) is the first-line therapy for obstructive sleep apnea (OSA). Overnight PAP titration for determining optimal PAP requirements is expensive and often inconvenient. Prediction of optimal PAP requirements from diagnostic polysomnography via mathematical equations is possible but variable across populations.

AIMS

We aimed to (1) determine the optimal PAP requirement, (2) determine differences in optimal PAP requirements across OSA severity groups, (3) determine the relationship between optimal PAP requirement and diagnostic polysomnography measurements of OSA severity, and (4) develop a pilot equation to predict the optimal PAP requirement from diagnostic polysomnography in a sample from the Saudi population.

METHODS

We analyzed records pertaining to adult OSA patients (n = 215; 63% of males) who underwent standardized diagnostic and titration polysomnography in our sleep laboratory between 2015 and 2019. Demographic, anthropometric, and clinical information were also collected for the analysis. Inferential statistics were performed for comparisons between diagnostic and titration studies and between OSA severity groups. Regression analyses were also performed to determine the potential predictors of optimal PAP requirements. Data were presented as the mean (± standard deviation) or median (25th-75th quartiles) according to normality.

RESULTS

The median optimal PAP requirement was 13 (9-17) cmH2O. The optimal PAP requirement was significantly greater for male versus female participants (14 [10-17] vs. 12 [8-16] cmH2O) and for participants with severe OSA (16 [12-20] cmH2O, n = 119) versus those with moderate (11 [8-14] cmH2O, n = 63) or mild (9 [7-12] cmH2O, n = 33) OSA. When combined, nadir oxygen saturation, oxygen desaturation index, and arousal index could be used to predict the optimal PAP requirement (R 2= 0.39, F = 34.0, P < 0.001).

CONCLUSIONS

The optimal PAP requirement in the Saudi population is relatively high and directly correlated with OSA severity. Diagnostic polysomnography measurements of OSA severity predicted the optimal PAP requirement in this sample. Prospective validation is warranted.

Determination of equation for estimating continuous positive airway pressure in patients with obstructive sleep apnea for the Indian population

Background:

Continuous positive airway pressure (CPAP) is the treatment of obstructive sleep apnea (OSA). The CPAP pressure is generally estimated by manual titration or an auto CPAP device. An alternative method involves the use of the predictive equation.

Aim and Objective:

There is no equation developed, taking into account the Indian population. The aim is to develop a predictive equation for optimal CPAP pressure in patients with OSA and to validate the equation by comparing it with manual titration pressure.

Materials and Methods:

A total of 250 patients with OSAS who underwent successful manual titration for CPAP treatment in a tertiary care center were included in this study and divided randomly into two groups A and B with 150 and 100 patients, respectively. Stepwise multiple regression analysis was applied to anthropometric and polysomnographic variables of group A and the predictive equation for estimating CPAP was developed using SPSS. This equation was validated by comparing the estimated pressure with that of manual titration pressure in Group B.

Results:

The mean age was 55.09 ± 11.43 and mean body mass index (BMI) was 33.69 ± 6.56. CPAP pressure in patients with OSA was 11.13 ± 1.83 cm H₂O. The Apnea Hypopnea index (AHI) (r = 0.595, P < 0.001), minimal; SpO₂ (r = −0.502, P < 0.001), BMI (r = 0.494, P < 0.001) significantly correlated with optimal CPAP level. A predictive equation for optimal CPAP level in patients with OSA was developed using AHI, BMI, and minimal SpO₂, which can be easily measured during the diagnostic process. Optimal CPAP level (cm H₂O) =8.401+ (0.053 × BMI) + (0.020 × AHI) − (0.031 × lowest oxygen). Twenty-six percent of the variance in the optimal CPAP level was explained by this equation (R² = 0.26, P < 0.001) and the equation showed 86% of optimal estimation.

Conclusion:

The results suggest that manual titration pressure correlates with the pressure derived from the predictive equation in our study.

Intermittent hypoxia causes mandibular growth retardation and macroglossia in growing rats

INTRODUCTION

In this study, we aimed to examine the role of intermittent hypoxia (IH) in dentofacial morphologic changes in growing rats.

METHODS

Seven-week-old male rats were exposed to IH at 20 cycles per hour (nadir of 4% oxygen to peak of 21% oxygen) for 8 hours per day for 6 weeks. Control rats were exposed to normoxia (N). Maxillofacial growth was compared between the 2 groups by linear measurements on cephalometric radiographs. To examine the dental arch morphology, study models and microcomputed tomography images of the jaws were taken. Additionally, tongue size was measured.

RESULTS

The gonial angle and the ramus of the mandible were smaller in the IH group than in the N group, whereas the body weights were not different between the 2 groups. Morphometric analysis of the dentition showed a significantly wider mandibular dentition and narrower maxillary dentition in the IH than in the N group. The relative width (+4.2 %) and length (tongue apex to vallate papillae, +3.5 %) of the tongue to the mandible were significantly greater in the IH group than in the N group.

CONCLUSIONS

IH induced dentofacial morphologic discrepancies in growing rats.

Oropharyngeal Crowding Closely Relates to Aggravation of OSA

BACKGROUND

Obesity is known to be an important risk factor for OSA; however, OSA can also be seen in nonobese patients with a small maxilla and/or mandible as well as in all obese patients with such features. Thus, we hypothesized that regional factors, oropharyngeal crowding associated with fat deposition, and maxillomandibular enclosure size closely related to the severity of OSA.

METHODS

A total of 703 male Japanese subjects were enrolled; theywere classified into obese (BMI ≥ 30 kg/m(2); n = 158) and nonobese (BMI < 30 kg/m(2); n = 545) groups. Using lateral cephalometric analysis, we measured the tongue size (TG), lower face cage (LFC), and TG/LFC ratio (ie, oropharyngeal crowding) to evaluate the state of upper airway crowding. The correlations between these cephalometric measurements and BMI, age, and the apnea-hypopnea index (AHI) were evaluated.

RESULTS

In obese subjects, the TG/LFC ratio, BMI, and TG positively correlated with AHI, whereas, in nonobese subjects, age, BMI, and TG/LFC significantly correlated with AHI. Subsequent stepwise multiple linear regression analysis revealed that the variables associated with AHI differed between obese and nonobese OSA subjects, although BMI and TG/LFC were significantly associated with AHI in both groups. In particular, the contribution of TG/LFC to AHI was larger than that of BMI in the obese group.

CONCLUSIONS

Oropharyngeal crowding is a local anatomic factor that independently relates to the severity of OSA in both obese and nonobese patients; the more crowded the upper airway, the more severe the OSA.

Mathematical Equations to Predict Positive Airway Pressures for Obstructive Sleep Apnea: A Systematic Review

Objective. To systematically review the international literature for mathematical equations used to predict effective pressures for positive airway pressure (PAP) devices. Methods. Google Scholar, PubMed, Scopus, Embase, Web of Science, CINAHL, and The Cochrane Library were searched through June 27, 2015. The PRISMA statement was followed. There was no language limitation. Results. 709 articles were screened, fifty were downloaded, and twenty-six studies presented equations that met the inclusion and exclusion criteria. In total, there were 4,436 patients in the development phases and 3,489 patients in the validation phases. Studies performed multiple linear regressions analyses as part of the equation(s) development and included the following variables: physical characteristics, polysomnography data, behavioral characteristics, and miscellaneous characteristics, which were all predictive to a variable extent. Of the published variables, body mass index (BMI) and mean oxygen saturation are the most heavily weighted, while BMI (eighteen studies), apnea-hypopnea index (seventeen studies), and neck circumference (eleven studies) were the variables most frequently used in the mathematical equations. Ten studies were from Asian countries and sixteen were from non-Asian countries. Conclusion. This systematic review identified twenty-six unique studies reporting mathematical equations which are summarized. Overall, BMI and mean oxygen saturation are the most heavily weighted.

Craniofacial contribution to residual obstructive sleep apnea after adenotonsillectomy in children: a preliminary study

STUDY OBJECTIVES

Pediatric obstructive sleep apnea (OSA) is frequently associated with adenotonsillar hypertrophy, and the fact that about 30% of affected children continue to show OSA after adenotonsillectomy (AT) suggests the presence of some other predisposing factor(s). We hypothesized that abnormal maxillofacial morphology may be a predisposing factor for residual OSA in pediatric patients.

METHODS

A total of 13 pediatric OSA patients (9 boys and 4 girls, age [median (interquartile range)] = 4.7 (4.0, 6.4) y, body mass index (BMI) z score = -0.3 (-0.8, 0.5)) who had undergone AT were recruited for this study. Maxillomandibular size was measured using an upright lateral cephalogram, and correlations between size and the apnea hypopnea index (AHI) values obtained before (pre AT AHI) and about 6 months after AT (post AT AHI) were analyzed.

RESULTS

AHI decreased from 12.3 (8.9, 26.5)/h to 3.0 (1.5, 4.6)/h after AT (p < 0.05). Residual OSA was seen in 11 of the 13 patients (84.6%) and their AHI after AT was 3.1 (2.7, 4.7)/h. The mandible was smaller than the Japanese standard value, and a significant negative correlation was seen between maxillomandibular size and post AT AHI (p < 0.05).

CONCLUSIONS

These findings suggest that the persistence of OSA after AT may be partly due to the smaller sizes of the mandible in pediatric patients. We propose that the maxillomandibular morphology should be carefully examined when a treatment plan is developed for OSA children.