Pilot study of the effects of bariatric surgery and continuous positive airway pressure treatment on vascular function in obese subjects with obstructive sleep apnoea

Impact of bariatric surgery on carotid intima-media thickness, flow-mediated dilation, and nitrite-mediated dilation: a systematic review and meta-analysis

Obesity is considered one of the independent risk factors for atherosclerosis and is strongly correlated with cardiovascular morbidity and mortality. Previous studies showed carotid intima-media thickness (CIMT), flow-mediated dilation (FMD), and nitrite-mediated dilatation (NMD) are reliable non-invasive markers of arterial damage and dysfunction. The aim of this study was to evaluate the effect of bariatric surgery on CIMT, FMD, and NMD markers in patients with obesity. A systematic search was performed in the PubMed, Embase, Scopus, and Web of Science databases until May 2022. All the English-published studies on the effect of bariatric surgery on CIMT, FMD, and NMD were included. A quantitative meta-analysis was performed, as well as subgroup analyses for the type of procedure and duration of follow-up. Meta-analysis of 41 studies with 1639 patients showed CIMT was significantly reduced by .11 mm after bariatric surgery (95% CI, -.14 to -.08; P < .001; mean follow-up = 10.8 mo). The pooled analysis of 23 studies with 1106 patients showed an increase of FMD by 4.57% after bariatric surgery (95% CI, 2.69-6.44; P < .001; mean follow-up = 11.5 mo). The results of a pooled analysis of 12 studies with 346 patients showed a significant increase of NMD by 2.46% after bariatric surgery (95% CI, .99-3.94; P < .001; mean follow-up = 11.4 mo). The random effect meta-regression demonstrated that baseline CIMT and FMD significantly affect the changes in CIMT and FMD. This meta-analysis showed bariatric surgery can improve CIMT, FMD, and NMD markers in patients with obesity. These improvements show the known effect of metabolic surgery in decreasing cardiovascular risk.

Effect of Bariatric Surgery on Flow-Mediated Vasodilation as a Measure of Endothelial Function: A Systematic Review and Meta-Analysis

Objectives. Flow mediated vasodilation (FMD) is a marker of endothelial function and its decline is related to increased cardiovascular risk. This systematic review and meta-analysis evaluated the impact of bariatric surgery on FMD. Materials and methods. A systematic literature search in PubMed, Scopus, Embase, and Web of Science was performed to 1 May 2021. Meta-analysis was performed using Comprehensive Meta-Analysis (CMA) V2 software. All types of bariatric surgery were considered, with the inclusion that FMD had to have been tested before and after the surgical procedure. Meta-analysis was carried out using a random-effects model and the generic inverse variance approach. The leave-one-out approach was used for sensitivity analysis. To assess metabolic parameter confounders, a weighted random-effects meta-regression was used. Results. A meta-analysis and a systematic review of 23 studies (n = 891 individuals) demonstrated improvement in FMD following bariatric surgery (weighted mean difference (WMD): 5.867, 95% CI: 4.481, 7.252, p < 0.001; I2: 96.70). Iteratively removing each item in the meta-analysis did not result in a significant alteration in the pooled estimate of effect size. There was an improvement in FMD for up to 6 months following bariatric surgery in a meta-analysis from 7 trials that included 356 subjects (WMD: 5.248, 95% CI: 2.361, 8.135, p < 0.001; I2: 98.18). The meta-analysis from 9 trials (n = 414 subjects) showed an improvement in FMD 6 to 12 months after bariatric surgery (WMD: 5.451, 95% CI: 3.316, 7.587, p < 0.001; I2: 94.18). The meta-analysis from 10 trials (n = 414 subjects) demonstrated an improvement in FMD 12 months after bariatric surgery (WMD: 2.401, 95% CI: 0.944, 3.859, p = 0.001; I2: 88.35). Random-effects meta-regression did not show any association between the alteration in FMD and percent body mass index (BMI) change (slope: 0.0258; 95% CI: −0.323, 0.375; p = 0.884), or changes in blood pressure; however, there was an association between the changes in FMD and the duration of follow-up (slope: −0.106; 95% CI: −0.205, −0.008; p = 0.033) with greater changes in FMD after 12 months. Conclusions. Bariatric surgery significantly improved FMD that increased with time, and the resultant improvement in endothelial function was independent of weight loss or a reduction in blood pressure.

Effect of different treatments for obstructive sleep apnoea on blood pressure

OBJECTIVE

Obstructive sleep apnoea (OSA) is a common cause of secondary hypertension. This network meta-analysis (NMA) assessed the effect of different OSA treatments on lowering blood pressure.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for relevant randomized controlled trials. The search strategies included the concepts of OSA, blood pressure, hypertension, and blood pressure-reducing treatments without language or data restriction (from inception to 1 June 2021). The outcomes included office SBP, office DBP, daytime SBP (dSBP) and DBP (dDBP), and night-time SBP (nSBP) and DBP (nDBP). A Bayesian network meta-analysis was performed, and mean differences with 95% credibility intervals were calculated.

RESULTS

We reviewed 49 randomized controlled trials involving 4893 patients and the following interventions: continuous positive-airway pressure (CPAP), mandibular advancement devices, nocturnal supplemental oxygen, surgery, β-blocker, angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs), renal sympathetic denervation (RDN), mineralocorticoid receptor antagonists (MRAs), calcium channel blockers. MRAs were significantly associated with blood pressure reduction followed by ACEI/ARB. RDN could reduce office SBP, office DBP, 24-h SBP, 24-h DBP, dSBP, and dDBP. CPAP also demonstrated modest blood pressure lowering.

CONCLUSION

MRAs and ACEIs/ARBs can reduce blood pressure effectively in patients with OSA. RDN is a novel hypertension treatment that lowered blood pressure in such patients. CPAP was associated with mild but stable blood pressure reduction, and it might be helpful as an adjunctive therapy in OSA patients with hypertension.

REVIEW REGISTRATION

This systematic review and meta-analysis was registered in PROSPERO: CRD42021240891.

Referral of adults with obstructive sleep apnea for surgical consultation: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment

INTRODUCTION

This systematic review provides supporting evidence for the accompanying clinical practice guideline on the referral of adults with obstructive sleep apnea (OSA) for surgical consultation.

METHODS

The American Academy of Sleep Medicine commissioned a task force of experts in sleep medicine. A systematic review was conducted to identify studies that compared the use of upper airway sleep apnea surgery or bariatric surgery to no treatment as well as studies that reported on patient-important and physiologic outcomes pre- and postoperatively. Statistical analyses were performed to determine the clinical significance of using surgery to treat obstructive sleep apnea in adults. Finally, the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence for making recommendations.

RESULTS

The literature search resulted in 274 studies that provided data suitable for statistical analyses. The analyses demonstrated that surgery as a rescue therapy results in a clinically significant reduction in excessive sleepiness, snoring, blood pressure (BP), apnea-hypopnea index (AHI), respiratory disturbance index (RDI), oxygen desaturation index (ODI), increase in lowest oxygen saturation (LSAT), sleep quality, and improvement in quality of life in adults with OSA who are intolerant or unaccepting of positive airway pressure (PAP) therapy. The analyses demonstrated that surgery as an adjunctive therapy results in a clinically significant reduction in optimal PAP pressure and improvement in PAP adherence in adults with OSA who are intolerant or unaccepting of PAP due to side effects associated with high pressure requirements. The analyses also demonstrated that surgery as an initial treatment results in a clinically significant reduction in AHI/RDI, sleepiness, snoring, BP, and ODI, and increase in LSAT in adults with OSA and major anatomical obstruction. Analysis of bariatric surgery data showed a clinically significant reduction in BP, AHI/RDI, sleepiness, snoring, optimal PAP level, BMI, ODI, and an increase in LSAT in adults with OSA and obesity. Analyses of very limited evidence suggest that upper airway surgery does not result in a clinically significant increase in risk of serious persistent adverse events and suggested that bariatric surgery may result in a clinically significant risk of iron malabsorption that may be managed with iron supplements. The task force provided a detailed summary of the evidence along with the quality of evidence, the balance of benefits and harms, patient values and preferences, and resource use considerations.

Effect of positive end-expiratory pressure ventilation on plasma nitric oxide, endothelin-1 and vascular celladhesion molecule-1 levels in patients undergoing uvulopalatopharyngoplasty

BACKGROUND

During uvulopalatopharyngoplasty (UPPP), cardiovascular adverse events may occur which can be harmful to patients.

OBJECTIVE

To evaluate the effect of the protective ventilation strategy on the function of vascular endothelial cells.

METHODS

Forty obstructive apnea syndrome (OSA) patients who underwent uvulopalatopharyngoplasty (UPPP) were enrolled. Patients were randomly divided into the control group (group C, PEEP = 0 cm H2O) and PEEP group (group P, PEEP = 5 cm H2O). Each group (n= 20) received intermittent volume controlled ventilation (VCV) with tidal volume 6 ml/kg of the predicted body weight, I:E 1:2, rate titrated for ETCO2 35-45, FiO2 0.7. Blood from the radial artery was sampled for blood gas analysis at four time points: the fifth minute of inhaling pure oxygen (T0), after tracheal intubation (T1), at the end of the operation (T2), and 20 minutes after extubation (T3). Three ml of arterial blood was retained, preserved at -20∘C after serum isolation, and plasma nitric oxide (NO), endothelin-1 (ET-1) and vascular celladhesion molecule-1 (VCAM-1) levels were determined by enzyme linked immunosorbent assay (ELISA).

RESULTS

Compared with group C, plasma ET-1 at T3 decreased in group P, and plasma NO levels at T2 and T3 increased (P< 0.05). Compared with samples collected at T0, plasma VCAM-1 levels at T1, T2 and T3 increased in group C, while plasma VCAM-1 levels at T2 and T3 decreased in group P (P< 0.05). Compared with group C, plasma VCAM-1 levels T2 and T3 decreased in group P (P< 0.05).

CONCLUSIONS

Positive end-expiratory pressure (PEEP) ventilation has a protective effect on vascular endothelial cell function in patients during UPPP.

The Effect of Continuous Positive Airway Pressure on Vascular Function and Cardiac Structure in Diabetes and Sleep Apnea. A Randomized Controlled Trial

Rationale: Although both type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are independently recognized as risk factors for cardiovascular disease, little is known about their interaction.Objectives: We hypothesized that T2DM and OSA act synergistically to increase vascular risk, and that treatment of OSA would improve vascular reactivity in patients with T2DM plus OSA.Methods: Cross-sectional study of 141 adults with T2DM, OSA, T2DM plus OSA, and control subjects, followed by a 3-month, parallel-arm, randomized, placebo-controlled trial comparing active and sham continuous positive airway pressure (CPAP) in 53 adults with T2DM plus OSA. Endothelium-dependent macro- and microvascular reactivity (flow-mediated dilation [FMD] of the brachial artery and acetylcholine-induced dilation of forearm microvasculature, respectively) and cardiovascular magnetic resonance to assess left- and right-ventricular mass/volume.Results: Mean (±SD) FMD was 6.1 (±4.0)%, 7.3 (±3.6)%, 6.8 (±4.5)%, and 4.8 (±2.9)% in control subjects, T2DM only, OSA only, and T2DM plus OSA, respectively. We observed a significant T2DM × OSA interaction on FMD, such that the mean effect of OSA in those with T2DM was 3.1% (95% confidence interval [CI], 0.6 to 5.6) greater than the effect of OSA in those without T2DM. A total of 3 months of CPAP resulted in a mean absolute increase in FMD of 0.3% (95% CI, -1.9 to 2.5; primary endpoint), with a net improvement of 1.1% (95% CI, -1.4 to 3.6) among those with adherence of 4 h/night or greater. A significant T2DM × OSA interaction was found for both left ventricular (LV) and right ventricular end-diastolic volume, such that OSA was associated with a 22.4 ml (95% CI, 3.2 to 41.6) greater LV end-diastolic volume and 23.2 ml (95% CI, 2.6 to 43.8) greater right ventricular end-diastolic volume in those with T2DM compared with the impact of OSA in those without T2DM. We observed a net improvement in LV end-diastolic volume of 8.7 ml (95% CI, -7.0 to 24.4).Conclusions: The combination of T2DM plus OSA is associated with macrovascular endothelial dysfunction beyond that observed with either disease alone. CPAP for 3 months did not significantly improve macrovascular endothelial function in the intent-to-treat analysis; however, cardiovascular magnetic resonance results suggest that there may be a beneficial effect of CPAP on LV diastolic volume.Clinical trial registered with www.clinicaltrials.gov (NCT01629862).

A pilot study on the biomechanical assessment of obstructive sleep apnea pre and post bariatric surgery

Obesity is a major risk factor for obstructive sleep apnea patients. In obese patients the severity of this risk can be reduced by bariatric surgery. This pilot study investigates the perioperative effects of bariatric surgery on obstructive sleep apnea and on the physical and biomechanical characteristics of the upper airway. Polysomnography and computer tomography data for 10 morbid obese patients promoted for bariatric surgery were conducted before surgery and at 6 and 12 months postoperatively for assessment of the oropharyngeal anatomy, and subsequent three-dimensional modelling of the airway. Mean values for the apnea/hypopnea index and body mass index significantly reduced after surgery. To combine the effect of changes in the upper airway volume and body mass index, a new volume body mass index is introduced. This index increases with a successful bariatric surgery. Although bariatric surgery leads to an effective weight reduction for all age groups, for obstructive sleep apnea patients it may be effective for middle age, less effective for 50-60 years, and further less effective for patients over the age of 60 years.

Which place of pharmacological approaches beyond continuous positive airway pressure to treat vascular disease related to obstructive sleep apnea?

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete upper airway obstruction, occurring during sleep, leading to chronic intermittent hypoxia (IH), which harms the cardiovascular system. OSA is associated with both functional and structural vascular alterations that contribute to an increased prevalence of fatal and non-fatal cardiovascular events. OSA is a heterogeneous disease with respect to the severity of hypoxia, the presence of daytime symptoms, obesity, and cardiovascular comorbidities. Various clusters of OSA phenotypes have been described leading to more highly personalized treatment. The aim of this review is to describe the various therapeutic strategies including continuous positive airway pressure (CPAP), oral appliances, surgery, weight loss, and especially pharmacological interventions that have been evaluated to reduce vascular alterations in both OSA patients and preclinical animal models. Conventional therapies, predominantly CPAP, have a limited impact on vascular alterations in the presence of co-morbidities. A better knowledge of pharmacological therapies targeting IH-induced vascular alterations will facilitate the use of combined therapies and is crucial for designing clinical trials in well-defined OSA phenotypes.

Derived Arterial Stiffness is Increased in Patients with Obstructive Sleep Apnea and Periodic Limb Movements during Sleep

STUDY OBJECTIVES

Both periodic limb movements during sleep (PLMS) and obstructive sleep apnea (OSA) have been associated with increased risk of cardiovascular disease (CVD). OSA has also been linked to increased large arterial stiffness, which is considered an independent risk factor for CVD. We utilized a previously validated index of large artery stiffness (SIDVP) derived from the digital volume pulse (DVP) to seek comparison in patients with PLMS and OSA.

METHODS

Forty-nine adult male subjects, without known comorbidities that could affect arterial stiffness or on vasoactive medication, were retrospectively identified and categorized into controls (n = 8), PLMS (n = 13), OSA (n = 17), and OSA/PLMS (n = 11). The cutoff for PLMS was a periodic limb movement index (PLMI) > 15 events/h, and for OSA an apnea-hypopnea index (AHI) > 10 events/h. SIDVP was derived from the raw data of photoplethysmography of the nocturnal polysomnography, averaged for 2 min prior to sleep study initiation (baseline), after completion in the morning, and every half hour after sleep onset.

RESULTS

The groups were age/body mass index-matched. Controls showed lower baseline, morning, and overall SIDVP compared to the other groups (p < 0.01). Patients with PLMS (PLMI: 50.69 ± 9.7 events/h) and the OSA group (AHI: 29.7 ± 2 events/h) demonstrated similar overall SIDVP (6.78 ± 0.08 versus 6.94 ± 0.04, respectively, p = 0.5), whereas the OSA/PLMS (AHI: 29.35 ± 8, PLMI: 50.63 ± 7.2) group demonstrated the highest (7.40 ± 0.06, p < 0.001).

CONCLUSIONS

Based on an easily reproducible and applicable marker of large arterial stiffness, patients with significant PLMS had higher SIDVP when compared to controls and comparable to those with moderate/severe OSA. The OSA/PLMS group had the highest SIDVP, implying a possible additive effect of OSA and PLMS on arterial stiffness.

STOP-Bang and the effect on patient outcome and length of hospital stay when patients are not using continuous positive airway pressure

BACKGROUND

In patients undergoing surgical interventions under general anesthesia, obstructive sleep apnea syndrome (OSA) can cause serious perioperative cardiovascular or respiratory complications leading to fatal consequences, even sudden death. In this study we test the hypothesis that morbidly obese patients diagnosed by a polysomnography test and using continuous positive airway pressure (CPAP) therapy have fewer and less severe perioperative complications and a shorter hospital stay than patients who have a medical history that meets at least three STOP-Bang criteria and are not using CPAP therapy.

METHODS

Postoperative hospital stay and pulmonary complications were analyzed in three groups of morbidly obese patients undergoing bariatric surgery (Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy) between January 2009 and November 2013 (n = 693). Group A comprised 99 patients who were preoperatively diagnosed with OSA based on polysomnography results. These patients used CPAP therapy before and after surgery. Group B consisted of 182 patients who met at least three STOP-Bang criteria but who were not diagnosed with OSA based on polysomnography results. These patients did not use CPAP. Group C, the reference group, comprised 412 patients who scored one to two items on the STOP-Bang.

RESULTS

During the perioperative period, Group B patients had a significantly (p < 0.001) higher cumulative rate of pulmonary complications, worse oxygen saturation, respiratory rates, and increased length of stay in hospital. There was also two cases of sudden death in this group.

CONCLUSION

Based on these results, we conclude that patients meeting at least three STOP-BANG criteria have higher postoperative complications and an increased length of hospital stay than patients using CPAP.