Neck circumference and lowest oxygen saturation are independently associated with high coexistence of hypertension in obstructive sleep apnea

A risk prediction nomogram for resistant hypertension in patients with obstructive sleep apnea

Patients with obstructive sleep apnea (OSA) are liable to have resistant hypertension (RH) associated with unfavorable cardiovascular events. It is of necessity to predict OSA patients who are susceptible to resistant hypertension. Hence, we conducted a retrospective study based on the clinical records of OSA patients admitted to Yixing Hospital Affiliated to Jiangsu University from January 2018 to December 2022. According to different time periods, patients diagnosed between January 2018 and December 2021 were included in the training set (n = 539) for modeling, and those diagnosed between January 2022 and December 2022 were enrolled into the validation set (n = 259) for further assessment. The incidence of RH in the training set and external validation set was comparable (P = 0.396). The related clinical data of patients enrolled were collected and analyzed through univariate analysis and least absolute shrinkage and selection operator (LASSO) logistic regression analysis to identify independent risk factors and construct a nomogram. Finally, five variables were confirmed as independent risk factors for OSA patients with RH, including smoking, heart disease, neck circumference, AHI and T90. The nomogram established on the basis of variables above was shown to have good discrimination and calibration in both the training set and validation set. Decision curve analysis indicated that the nomogram was useful for a majority of OSA patients. Therefore, our nomogram might be useful to identify OSA patients at high risk of developing RH and facilitate the individualized management of OSA patients in clinical practice.

Comparison of clinical features and surgical outcomes between hypopnea- and apnea-predominant obstructive sleep apnea

OBJECTIVES

This study is aimed to investigate the differences in the clinical features and surgical outcomes between hypopnea- and apnea-predominant obstructive sleep apnea (OSA).

DESIGN

Cohort study.

SETTING

Single tertiary care centre.

PARTICIPANTS

This study included 190 patients with OSA who underwent multilevel upper airway surgery between September 2012 and September 2021. The patients were divided into two groups according to the proportion of each respiratory event: hypopnea-predominant (n = 102) and apnea-predominant (n = 88).

MAIN OUTCOME MEASURES

The primary outcome measure was the percentage improvement in the apnea-hypopnea index (AHI) from baseline AHI after surgery.

RESULTS

The apnea-predominant group included more male patients and had higher AHI, respiratory disturbance index (RDI) and oxygen desaturation index (ODI) than the hypopnea-predominant group. Both groups showed significant improvements in AHI, apnea index, RDI, supine AHI, REM AHI, non-REM AHI, ODI, lowest O₂ saturation and Epworth Sleepiness Scale scores following the surgery. Notably, hypopnea index increased after surgery in the apnea-predominant OSA group. Although the improvement in the absolute value of AHI by surgery was significantly greater in the apnea-predominant group than in the hypopnea-predominant group, the two groups showed no significant difference in the percentage improvement in AHI from baseline AHI.

CONCLUSION

Patients with apnea-predominant OSA had more severe disease than those with hypopnea-predominant OSA; however, surgical outcomes, as evaluated by percentage AHI improvement, were comparable between the two groups. In addition, multilevel upper airway surgery may induce the transition from apnea to hypopnea in patients with apnea-predominant OSA.

Long-Term Effects of Continuous Positive Airway Pressure (CPAP) Therapy on Obesity and Cardiovascular Comorbidities in Patients with Obstructive Sleep Apnea and Resistant Hypertension-An Observational Study

BACKGROUND

We sought to investigate whether long-term continuous positive airway pressure (CPAP) treatment in patients with obstructive sleep apnea (OSA) and resistant hypertension (RHTN) could attenuate the cardiovascular disease risk by lowering their body-mass index (BMI).

METHODS

This was a long-term observational study of RHTN patients diagnosed with OSA. Patients were evaluated with polysomnography initially and after a mean follow-up period of four years. The patients were divided into two groups based on their compliance to CPAP therapy.

RESULTS

33 patients (aged 54.67 ± 7.5, 18 men, 54.5%) were included in the study, of which 12 were compliant to CPAP therapy. A significant reduction in BMI at follow-up was noted in patients compliant to CPAP therapy (1.4 ± 3.5 vs. -1.6 ± 2.5, p = 0.006). We also noted a large effect size reduction in abdominal circumference at follow-up in the CPAP group. At follow-up evaluation, the mean heart rate (b/min) was lower in the CPAP group (58.6 ± 9.5 vs. 67.8 ± 7.8), while arrhythmia prevalence increased between initial (28.6%) and follow-up (42.9%) evaluation with an intermediate effect size in non-compliant patients.

CONCLUSIONS

In our cohort of OSA patients with RHTN, long-term adherence to CPAP therapy was associated with weight loss and improvement in cardiac rhythm outcomes.

Neck circumference is independently associated with relative systemic hypertension in young adults with sickle cell anaemia

Background

A seemingly interesting observation in patients with sickle cell anaemia (SCA) is that they usually have lower systemic blood pressures (BP) and insulin resistance than persons in the general population in spite of chronic inflammation and vasculopathy. However, relative systemic hypertension (rHTN) has been linked to pulmonary hypertension, increased blood viscosity and renal insufficiency, which could indicate a risk of developing cardiometabolic disorder (CMD) in SCA.

We therefore hypothesized that neck circumference (NC) and CMD marker; triglyceride glucose (TyG) index would independently predict rHTN in young adults with SCA in steady state.

Methods

We compared the anthropometrical, hematological, hemorheological and CMD markers between SCA patients with normal BP < 120/70 mmHg; nHTN, n = 65) and those with rHTN (BP ≥ 120/70 mmHg, n = 32).

Results

Our results showed that SCA with rHTN had significantly higher body weight, waist circumference, NC, plasma viscosity, systolic and diastolic BP. Results also indicated that NC (OR: 2.98; 95% CI 1.46 to 6.10, p < 0.01) was a predictor of rHTN in SCA independent of gender, age, weight, waist circumference, BMI, blood viscosity, triglyceride or TyG. A receiver operating characteristic curve analysis also showed that NC was the most efficient predictor of rHTN than other CMD markers.

Conclusion

The present study demonstrates that increased NC is a salient risk factors that is independently associated with rHTN in SCA. The finding therefore underscores the utility of NC in early detection and stratification of systemic hypertension, particularly in individuals with SCA.

Lowest Oxyhemoglobin Saturation May Be an Independent Factor Influencing Auditory Function in Severe Obstructive Sleep Apnea

STUDY OBJECTIVES

The aims of this study were to determine if a correlation exists between the level of hypoxia induced by severe obstructive sleep apnea syndrome (OSAS) and the level of auditory dysfunction when verifying such a relationship using polysomnography (PSG).

METHODS

A retrospective review of 41 patients with severe OSAS was performed. Independent risk factors for hearing impairment included parameters of PSG, which were analyzed in two hearing groups at a level ≥ 40 decibels (dB).

RESULTS

Oxyhemoglobin saturation, especially the lowest oxyhemoglobin saturation level, showed lower thresholds in the hearing impairment group than in the control group (p = 0.039 at NREM stage; p = 0.029 at REM stage; p = 0.001 at total sleep stage). After adjusting for other risk factors, the sole variable that remained significant was lowest oxyhemoglobin saturation (total; p = 0.046). In the correlation analysis, a decreasing lowest oxyhemoglobin saturation (from all subjects, n = 41) correlated with a greater mean hearing threshold (R(2) = 0.297; p < 0.001).

CONCLUSION

Our results indicated that lowest oxyhemoglobin saturation in PSG is the only variable correlated with the hearing threshold. This finding could be predictive of possible hearing alternation in patients with severe OSAS.

COMMENTARY

A commentary on this article appears in this issue on page 641.

Longitudinal Effect of CPAP on BP in Resistant and Nonresistant Hypertension in a Large Clinic-Based Cohort

BACKGROUND

Clinic-based effectiveness studies of sleep-disordered breathing (SDB) treatment in reducing BP in resistant hypertension (RHTN) vs non-RHTN are sparse. We hypothesize that CPAP use in SDB reduces BP significantly in RHTN and non-RHTN in a large clinic-based cohort.

METHODS

Electronic medical records were reviewed in patients with SDB and comorbid RHTN and non-RHTN for CPAP therapy initiation (baseline) and subsequent visits. We estimated generalizable BP changes from multivariable mixed-effects linear models for systolic BP (SBP), diastolic BP, and mean arterial pressure, adjusting for RHTN status, age, sex, race, BMI, cardiac history, and diabetes and repeated measure correlation.

RESULTS

Of 894 patients, 130 (15%) had RHTN at baseline (age, 58 ± 12 years; 52% men; BMI, 36 ± 9 kg/m(2)). Patients with RHTN had significantly higher BP overall (P < .001), most notably for SBP (6.9 mm Hg; 95% CI, 3.84, 9.94). In the year following CPAP initiation, improvements in BP indexes did not generally differ based on RHTN status in which RHTN status was a fixed effect. However, there was a significant decrease in SBP (3.08 mm Hg; 95% CI, 1.79, 4.37), diastolic BP (2.28; 95% CI, 1.56, 3.00), and mean arterial pressure (2.54 mm Hg; 95% CI, 1.73, 3.36) in both groups.

CONCLUSIONS

In this clinic-based effectiveness study involving patients closely followed for BP control, a significant reduction of BP measures (strongest for SBP) was observed in response to CPAP which was similar in RHTN and non-RHTN groups thus informing expected clinical CPAP treatment response.

Tongue Volume Influences Lowest Oxygen Saturation but Not Apnea-Hypopnea Index in Obstructive Sleep Apnea

Objectives

The aim of this study was to identify correlations between sleep apnea severity and tongue volume or posterior airway space measured via three-dimensional reconstruction of volumetric computerized tomography (CT) images in patients with obstructive sleep apnea (OSA) for use in predicting OSA severity and in surgical treatment. We also assessed associations between tongue volume and Mallampati score.

Methods

Snoring/OSA male patients (n = 64) who underwent polysomnography, cephalometry, and CT scans were enrolled in this retrospective study. OSA was diagnosed when the apnea-hypopnea index (AHI) was greater than 5 (mild 5–14; moderate 15–29; severe>30). The patients were also categorized into the normal-mild group (n = 22) and the moderate-severe group (n = 42). Using volumetric CT images with the three-dimensional reconstruction technique, the volume of the tongue, posterior airway space volume, and intra-mandibular space were measured. The volumes, polysomnographic parameters, and physical examination findings were compared, and independent factors that are related to OSA were analysed.

Results

No associations between tongue volume or posterior airway space and the AHI were observed. However, multivariate linear analyses showed that tongue volume had significantly negative association with lowest O₂ saturation (r = 0.365, p = 0.027). High BMI was related to an increase in tongue volume. Modified Mallampati scores showed borderline significant positive correlations with absolute tongue volume (r = 0.251, p = 0.046) and standardized tongue volume (absolute tongue volume / intramandibular area; r = 0.266, p = 0.034). Between the normal-mild and moderate-severe groups, absolute tongue volumes were not different, although the standardized tongue volume in the moderate-severe group was significantly higher.

Conclusion

Absolute tongue volume showed stronger associations with lowest O₂ saturation during sleep than with the severity of AHI. We also found that high BMI was a relevant factor for an increase in absolute tongue volume and modified Mallampati grading was a useful physical examination to predict tongue size.