Acute Effects of Automated Continuous Positive Airway Pressure on Blood Pressure in Patients with Sleep Apnea and Hypertension

Auto-adjusted versus fixed positive airway pressure in patients with severe OSA: A large randomized controlled trial

BACKGROUND AND OBJECTIVE

Continuous positive airway pressure (CPAP) in the treatment of severe obstructive sleep apnoea (OSA) can be used in fixed CPAP or auto-adjusted (APAP) mode. The aim of this prospective randomized controlled clinical study was to evaluate the 3 month-efficacy of CPAP used either in fixed CPAP or APAP mode.

METHODS

Eight hundred one patients with severe OSA were included in twenty-two French centres. After 7 days during which all patients were treated with APAP to determine the effective pressure level and its variability, 353 and 351 patients were respectively randomized in the fixed CPAP group and APAP group. After 3 months of treatment, 308 patients in each group were analysed.

RESULTS

There was no difference between the two groups in terms of efficacy whatever the level of efficient pressure and pressure variability (p = 0.41). Exactly, 219 of 308 patients (71.1%) in the fixed CPAP group and 212 of 308 (68.8%) in the APAP group (p = 0.49) demonstrated residual apnoea hypopnoea index (AHI) <10/h and Epworth Score <11. Tolerance and adherence were also identical with a similar effect on quality of life and blood pressure evaluation.

CONCLUSION

The two CPAP modes, fixed CPAP and APAP, were equally effective and tolerated in severe OSA patients.

Comparative effects of CPAP and mandibular advancement splint therapy on blood pressure variability in moderate to severe obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is associated with increased blood pressure variability (BPV) and are risk factors for cardiovascular disease. We aimed to assess the comparative effects of two OSA therapies, continuous positive airway pressure (CPAP) and mandibular advancement splint (MAS), on BPV.

METHODS

This is a secondary analysis of data collected as part of a previously published randomised crossover trial of one month each of CPAP and MAS therapy. BPV was determined from 24-h-ambulatory blood pressure recordings in 92 patients with moderate to severe OSA at baseline and after one month of optimised treatment with each modality. BPV was assessed by three measures: Standard deviation of the mean (SD), Coefficient of variation (CoV), and the Average Real Variability (ARV) index.

RESULTS

Neither CPAP nor MAS therapy improved BPV, with no difference between treatments. BPV did not change in hypertensive OSA patients, however, there was a reduction in ARV of diastolic blood pressure in the effectively treated compared to ineffectively treated CPAP patients, Δ ARV 24-h-DBP (mmHg), -0.72 ± 2.14, 0.34 ± 1.52, P = 0.02, respectively. There was no difference between effective versus ineffective MAS treatment, Δ ARV 24-h-DBP (mmHg), -0.04 ± 2.4, 0.02 ± 1.9, P = 1.00, respectively.

CONCLUSIONS

One month of optimised CPAP or MAS therapy did not improve short term BPV in patients with moderate to severe OSA. The subgroup of patients on effective CPAP showed some improvement in BPV with CPAP but not MAS. Further work on the effect of OSA therapy on BPV following long-term therapy is needed.

Effects of short-term aerobic training versus CPAP therapy on heart rate variability in moderate to severe OSA patients

We compared the effects of 2-month CPAP or exercise training (ET) therapies on the autonomic balance in moderate to severe obstructive sleep apnea (OSA) through heart rate variability (HRV) analysis. Thirty-nine OSA patients were divided into CPAP (n = 18) and ET (n = 21) groups, being further split into hypertensive and non-hypertensive subgroups. All patients were submitted to continuous ECG recordings for HRV analysis. Hemodynamic parameters were recorded by oscillometry. Excessive daytime sleepiness and sleep quality were assessed through the Epworth Sleepiness Scale and the Pittsburgh questionnaire, respectively. ET decreased systolic arterial pressure in hypertensive and non-hypertensive participants when compared to baseline values, whereas diastolic arterial pressure was decreased only in non-hypertensive ones. CPAP had no effect over hemodynamic parameters in either subgroup. ET significantly increased the HRV parameters SDNN and pNN50 in non-hypertensive participants, while reducing the LF/HF ratio in both subgroups. CPAP significantly decreased SDNN in both subgroups. ET significantly decreased excessive daytime sleepiness in both subgroups, but did not affect sleep quality. CPAP significantly improved sleep quality in both subgroups, although global scores were still those of poor sleepers, while excessive daytime sleepiness was normalized only in hypertensive patients. In conclusion, while short-term ET modulated different HRV parameters, leading to a predominant vagal tone in the cardiac sympathovagal balance and decreasing blood pressure in moderate to severe OSA, short-term CPAP had next to no effect in these parameters. We believe ET should be considered as an adjunct interventional strategy in the conservative management of hypertensive or non-hypertensive OSA patients.

Baseline Lighter Sleep and Lower Saturation Are Associated With Improved Sleepiness and Adherence on Continuous Rather Than Autotitrating Positive Airway Pressure

The objective was to test whether there were better outcomes on switching from autotitrating positive airway pressure (APAP) to continuous positive airway pressure (CPAP) in a clinic sample of patients with obstructive sleep apnea (OSA). Patients prescribed APAP in 2015-2016 and belonging to a subset characterized by side effects, or suboptimal response or adherence, were advised a switch to CPAP following a CPAP titration polysomnography. The main analysis was for improvement (after switch from APAP to CPAP) in (1) sleepiness, wakefulness inability, and fatigue, using change from baseline in the Sleepiness-Wakefulness Inability and Fatigue Test (delta SWIFT), and Epworth Sleepiness Scale (delta ESS), and (2) adherence using percentage of days with ≥4-hour use and whether there was ≥4-hour use on ≥70% days. To determine possible predictors for switching, additional analysis was performed for differences at baseline between patients switching and those staying on APAP. A total of 148 patients were switched from APAP to CPAP and had greater improvement in delta SWIFT (5.2 vs 4.1, P = .004), greater improvement in delta ESS (3.6 vs 2.9, P = .011), and better adherence (79.4% vs 74.3%, P = .006) on CPAP than on APAP. More patients were adherent on CPAP than on APAP (83.1% vs 68.9%, P = .006). Patients switching had higher baseline arousal index and stage N1 sleep, and lower nadir oxygen saturation, than 96 patients not switching. Thus, there is a subset of patients with better outcomes after switching to CPAP than on APAP. Patients with baseline lighter sleep (indicated by more arousals and stage N1), or greater desaturation, may be more likely to do better on CPAP than on APAP. CPAP may be the preferable treatment in a significant subset of patients. If APAP is used first anyway, side effects, or suboptimal response or adherence, should lead to consideration of switching to CPAP based on a CPAP titration polysomnography.

Effects of continuous positive airway pressure in patients at high risk of obstructive sleep apnea during propofol sedation after spinal anesthesia

In patients with obstructive sleep apnea, short-term use of a continuous positive airway pressure mask improves oxygenation, decreases the apnea-hypopnea index, and reduces hemodynamic instability. In this study, we investigated the effects of use of a continuous positive airway pressure mask in patients at high risk of obstructive sleep apnea during propofol sedation after spinal anesthesia. Forty patients who underwent propofol sedation after spinal anesthesia for transurethral bladder or prostate resection with a STOP-Bang score of 3 or more were enrolled in this study. Patients were randomly divided into two groups: a simple oxygen mask group (n = 20) and a continuous positive airway pressure mask group (n = 20). After spinal anesthesia, propofol was injected at a target concentration of 1.3 mcg/ml via a target concentration control injector. ApneaLink™ was applied to all patients. Patients in the simple oxygen mask group were administered oxygen at a rate of 6 L/min through a simple facial mask. Patients in the CPAP mask group were connected to a pressurizer, and oxygen (6 L/min, 5-15 cm H₂O) was administered. Blood pressure, heart rate, respiratory rate, and oxygen saturation were recorded preoperatively, after spinal anesthesia, and every 5 min after the injection of propofol to observe hemodynamic changes. Apnea-hypopnea index was estimated using ApneaLink™. There were no significant differences in hemodynamic changes between the two groups. Apnea-hypopnea index was significantly reduced in the continuous positive airway pressure mask group compared to the simple facial mask group. Application of a continuous positive airway pressure mask in a patient at high risk of obstructive sleep apnea can lower the incidence of obstructive sleep apnea during sedation without a significant effect on hemodynamic stability.

Blood-pressure variability in patients with obstructive sleep apnea: current perspectives

Obstructive sleep apnea (OSA) is often associated with hypertension and other cardiovascular diseases. Blood pressure (BP) variability is part of the assessment of cardiovascular risk. In OSA, BP variability has been studied mainly as very short-term (beat-by-beat) and short-term (24-hour BP profile) variability. BP measured on consecutive heartbeats has been demonstrated to be highly variable, due to repeated peaks during sleep, so that an accurate assessment of nocturnal BP levels in OSA may require peculiar methodologies. In 24-hour recordings, BP frequently features a "nondipping" profile, ie, <10% fall from day to night, which may increase cardiovascular risk and occurrence of major cardiovascular events in the nocturnal hours. Also, BP tends to show a large "morning BP surge", a still controversial negative prognostic sign. Increased very short-term BP variability, high morning BP, and nondipping BP profile appear related to the severity of OSA. Treatment of OSA slightly reduces mean 24-hour BP levels and nocturnal beat-by-beat BP variability by abolishing nocturnal BP peaks. In some patients OSA treatment turns a nondipping into a dipping BP profile. Treatment of arterial hypertension in OSA usually requires both antihypertensive pharmacological therapy and treatment of apnea. Addressing BP variability could help improve the management of OSA and reduce cardiovascular risk. Possibly, drug administration at an appropriate time would ensure a dipping-BP profile.

Cardiorespiratory interaction with continuous positive airway pressure

The treatment of choice for obstructive sleep apnoea (OSA) is continuous positive airway pressure therapy (CPAP). Since its introduction in clinical practice, CPAP has been used in various clinical conditions with variable and heterogeneous outcomes. In addition to the well-known effects on the upper airway CPAP impacts on intrathoracic pressures, haemodynamics and blood pressure (BP) control. However, short- and long-term effects of CPAP therapy depend on multiple variables which include symptoms, underlying condition, pressure used, treatment acceptance, compliance and usage. CPAP can alter long-term cardiovascular risk in patients with cardiorespiratory conditions. Furthermore, the effect of CPAP on the awake patient differs from the effect on the patients while asleep, and this might contribute to discomfort and removal of the use interface. The purpose of this review is to highlight the physiological impact of CPAP on the cardiorespiratory system, including short-term benefits and long-term outcomes.

Acute effects of autoadjusting and fixed continuous positive airway pressure treatments on cardiorespiratory coupling in obese patients with obstructive sleep apnea

BACKGROUND

Treatment with positive airway pressure devices improved signs and symptoms of obstructive sleep apnea syndrome (OSA); however, auto-adjusting positive pressure (APAP) device was not as effective as continuous positive airway pressure (CPAP) in reducing arterial blood pressure and insulin resistance. The role played by autonomic cardiac regulation remains to be clarified. We aimed to test the effects of CPAP and APAP on autonomic regulation and cardiorespiratory coupling during sleep.

METHODS

We retrospectively analyzed full-night polysomnographic studies. 19 patients newly diagnosed with severe OSA (AHI>30) and 7 obese subjects without OSA (CON) were enrolled. Each OSA subject was assigned to CPAP or APAP treatment and underwent a sleep study after 1 week of treatment. Spectral and cross-spectral analyses of heart rate variability (HRV) and respiration were performed to assess autonomic profile and coherence (K2) between respiration and HF oscillation during sleep in CPAP, APAP and CON groups.

RESULTS

In CPAP and CON, LFnu and LF/HF, markers of sympathetic modulation, decreased from N2 to N3 and increased during REM sleep (p<0.001), while in APAP group, sympathetic modulation was significantly higher compared with those of CPAP and CON during all sleep stages. K2 values were lower in APAP compared with those in CPAP and CON.

CONCLUSION

APAP treatment was characterized by a greater sympathetic activation and it was associated with a lower cardio-respiratory coupling compared with CPAP. This might account for the different effects on cardiovascular risk factors induced by the two treatments.

Daytime leg pain after overnight continuous positive airway pressure titration

We report a case that showed transitional, severe emergent periodic limb movements during sleep (PLMS) in the first continuous positive airway pressure (CPAP) titration night and mild PLMS in the 3rd and 20th nights of CPAP titration in a 56-year-old woman after she was found to have severe obstructive sleep apnea (OSA). Severe PLMS in the initial CPAP night unexpectedly resulted in acute leg muscle soreness in the second morning. The case suggests that CPAP therapy in patients who suffer from severe OSA may provide a unique opportunity to look into the pathological mechanism of PLMS.

Effects of positive airway pressure treatment on clinical measures of hypertension and type 2 diabetes

PURPOSE

Mechanistic and observational studies support an independent increase in risk of hypertension and abnormal glucose metabolism associated with obstructive sleep apnea (OSA). However, the specific populations and outcomes that improve with treatment of OSA in clinical practice are not established. We examined the effectiveness of OSA treatment on clinical blood pressure and diabetes control measures in men with preexisting systemic hypertension or type 2 diabetes.

METHODS

A retrospective cohort of veterans (n = 221) with a new diagnosis of OSA and initiation of positive airway pressure treatment was identified using administrative databases and clinical records.

MEASUREMENTS AND RESULTS

Outcomes were changes in blood pressure (BP; mean of 3 highest recordings; systolic and diastolic) and glycemic control (mean of 3 highest fasting glucose and hemoglobinA1C values) at 3-6 months (T1) and 9-12 months (T2) following treatment compared to pretreatment. A generalized estimating equation model was used with adjustment for potential confounders: demographics, body mass index (BMI), OSA severity, Charlson comorbidity index, and pharmacologic treatment for hypertension and diabetes. Sustained independent effects of OSA treatment (mean change [95% CI]) were noted in both systolic BP (T1; -7.44 [-10.41 to -4.47] and T2; -6.81 [-9.94 to -3.67]) and diastolic BP (T1; -3.14, [-4.99 to -1.29] and T2; -3.69, [-5.53 to -1.85]). Diabetes control measures did not change with OSA treatment.

CONCLUSIONS

Treatment of OSA improves office blood pressure in hypertensive men. Prospective studies are necessary to better characterize specific populations with OSA that benefit from treatment with respect to progression of hypertension and type 2 diabetes.

Change in frequency of periodic limb movements during sleep with usage of continuous positive airway pressure in obstructive sleep apnea syndrome

Periodic limb movements during sleep (PLMS) sometimes newly appear on the night of continuous positive airway pressure (CPAP) titration in patients with obstructive sleep apnea syndrome (OSAS). To ascertain the incidence and causative factors of this phenomenon, we investigated differences in its prevalence and the factors associated with newly appeared and persistent PLMS on CPAP titration night. We retrospectively analyzed polysomnographic data of 997 consecutive OSAS outpatients who had undergone overnight CPAP titration. On the basis of changes in periodic limb movements index (PLMI) values (cut off level≥15/h) from baseline polysomnography (BPSG) to CPAP titration PSG, patients were assigned to one of four groups: persistent, CPAP-emergent, CPAP-disappeared, and non-PLMS. The rate of patients was 6.7% in the persistent group, 8.0% in the CPAP-emergent group, 4.0% in the CPAP-disappearance group, and 81.2% in the non-PLMS group. Multivariate logistic regression analysis revealed that a higher apnea-hypopnea index (AHI) on BPSG and ≥47years of age appeared to be associated with the CPAP-emergent group. The results suggest that elderly patients with higher AHI at BPSG may present with CPAP-emergent PLMS.

Changes in the heart rate variability in patients with obstructive sleep apnea and its response to acute CPAP treatment

Introduction

Obstructive Sleep Apnea (OSA) is a major risk factor for cardiovascular disease. The goal of this study was to demonstrate whether the use of CPAP produces significant changes in the heart rate or in the heart rate variability of patients with OSA in the first night of treatment and whether gender and obesity play a role in these differences.

Methods

Single-center transversal study including patients with severe OSA corrected with CPAP. Only patients with total correction after CPAP were included. Patients underwent two sleep studies on consecutive nights: the first night a basal study, and the second with CPAP. We also analyzed the heart rate changes and their relationship with CPAP treatment, sleep stages, sex and body mass index. Twenty-minute segments of the ECG were selected from the sleep periods of REM, no-REM and awake. Heart rate (HR) and heart rate variability (HRV) were studied by comparing the R-R interval in the different conditions. We also compared samples from the basal study and CPAP nights.

Results

39 patients (15 females, 24 males) were studied. The mean age was 50.67 years old, the mean AHI was 48.54, and mean body mass index was 33.41 kg/m² (31.83 males, 35.95 females). Our results showed that HRV (SDNN) decreased after the use of CPAP during the first night of treatment, especially in non-REM sleep. Gender and obesity did not have any influence on our results.

Conclusions

These findings support that cardiac variability improves as an acute effect, independently of gender or weight, in the first night of CPAP use in severe OSA patients, supporting the idea of continuous use and emphasizing that noncompliance of CPAP treatment should be avoided even if it is just once.

Heart rate variability, sleep and sleep disorders

Heart rate (HR) is modulated by the combined effects of the sympathetic and parasympathetic nervous systems. Therefore, measurement of changes in HR over time (heart rate variability or HRV) provides information about autonomic functioning. HRV has been used to identify high risk people, understand the autonomic components of different disorders and to evaluate the effect of different interventions, etc. Since the signal required to measure HRV is already being collected on the electrocardiogram (ECG) channel of the polysomnogram (PSG), collecting data for research on HRV and sleep is straightforward, but applications have been limited. As reviewed here, HRV has been applied to understand autonomic changes during different sleep stages. It has also been applied to understand the effect of sleep-disordered breathing, periodic limb movements and insomnia both during sleep and during the daytime. HRV has been successfully used to screen people for possible referral to a Sleep Lab. It has also been used to monitor the effects of continuous positive airway pressure (CPAP). A novel HRV measure, cardiopulmonary coupling (CPC) has been proposed for sleep quality. Evidence also suggests that HRV collected during a PSG can be used in risk stratification models, at least for older adults. Caveats for accurate interpretation of HRV are also presented.

APAP impact on metabolic syndrome in obstructive sleep apnea patients

PURPOSE

Prevalence of metabolic syndrome (MS) in obstructive sleep apnea (OSA) patients is high. The effect of autoadjusting positive airway pressure (APAP) on MS remains unclear. This study aimed to determine the prevalence of MS in OSA patients before and 6 months after APAP, and to identify potential determinants of metabolic status change.

METHODS

Seventy-four male patients with moderate to severe OSA were enrolled. MS diagnosis was established according to the National Cholesterol Education Program/Adult Treatment Panel III. APAP was prescribed to all patients.

RESULTS

In the studied population, mean age was 55.9 years (SD 10.7 years), median body mass index (BMI), Epworth sleepiness scale (ESS), and respiratory disturbance index (RDI) were 33.4 kg/m(2) (interquartile range (IQR) 8.4 kg/m(2)), 12.0 (IQR 8.0), and 46.9/h (IQR 33.6/h), respectively. Prevalence of MS before and 6 months after APAP was 63.5% and 47.3%, respectively, and this difference was statistically significant (p = 0.004). In the subgroup of patients with MS at baseline (n = 47), 14 did not present MS after APAP. In these patients, a significant negative association with RDI (p = 0.016) and a positive association with percent of total days of usage (p = 0.014) were found. Blood pressure (p = 0.018) and serum triglycerides (p = 0.001) had a statistically significant reduction during this period. In patients that still had MS, 22.2% presented a reduction of the number of MS criteria.

CONCLUSIONS

After 6 months, APAP reduced the prevalence of MS, mainly in patients with less severe OSA and with a better therapeutic compliance. Blood pressure and serum triglycerides reduction contributed to this metabolic status change.

Pulse wave analysis in a pilot randomised controlled trial of auto-adjusting and continuous positive airway pressure for obstructive sleep apnoea

PURPOSE

Non-invasive measurements of arterial stiffness including the augmentation index (AIx) and central blood pressure (BP) have been used to assess the cardiovascular health of patients with obstructive sleep apnoea (OSA), a well-established independent risk factor of cardiovascular disease. Continuous positive airway pressure (CPAP) can significantly reduce the AIx, but no studies have analysed the effect of auto-adjusting PAP (APAP) or studied morbidly obese patients with severe OSA at higher risk of cardiovascular disease. In this randomised, single-blinded crossover pilot trial, we aimed to compare the efficacy of CPAP with APAP (ResMed S8 Autoset II) in improving peripheral BP, central BP and the AIx, using SphygmoCor technology.

METHODS

Twelve severe OSA patients (mean±SD; apnoea-hypopnoea index, 75.8 ± 32.7; BMI, 49.9 ± 5.2 kg/m(2)) were consecutively recruited and received CPAP (mean pressure, 16.4 cm H(2)O) or APAP in random order for four nights at home, separated by a four-night washout. Cardiovascular measurements were taken at baseline, post-washout and following each treatment arm.

RESULTS

The polysomnographically recorded residual apnoea-hypopnoea index and compliance to treatment were not significantly different between arms (p > 0.05). There were no significant differences in peripheral or central BP between arms (p > 0.05). The AIx was lower with CPAP than APAP (by 5.8%), with a large effect size not reaching statistical significance (r = 0.61, p = 0.14).

CONCLUSION

The large effect size evident when comparing the AIx following CPAP and APAP indicates the need to perform an adequately powered trial in order to determine if APAP improves arterial stiffness to the same extent as CPAP.

Severe sleep apnea syndrome diagnosed with acute myocardial infarction

A 55-year-old man with acute myocardial infarction and no heart failure, had episodes of severe oxygen desaturation and apnea, while his hemodynamic parameters were stable. Sleep recordings revealed severe sleep apnea, and pulmonary function tests showed bronchial obstruction. Apnea and desaturation resolved on bi-level positive airway pressure. Patients with acute myocardial infarction who have apnea and hypoxemia without evident heart failure should be evaluated for sleep disorders.

Effect of CPAP on QT interval dispersion in obstructive sleep apnea patients without hypertension

OBJECTIVES

Delayed cardiac repolarization leading to prolongation of the QT interval is a well-characterised precursor of arrhythmias. Obstructive sleep apnea (OSA) might cause arrhythmias, since QT corrected interval dispersion (QTcd) is increased in these patients. We aimed to determine the effect of nasal continuous positive airway pressure (CPAP) therapy on QTcd in OSA patients without hypertension.

METHODS

An overnight polysomnography (PSG) and a standard 12-lead electrocardiogram (ECG) were performed on 49 subjects without hypertension, diabetes mellitus, cardiac or pulmonary disease or any hormonal, hepatic, renal or electrolyte disorders. In 29 moderate-severe OSA (apnea-hypopnea index: AHI15) patients, QTd (defined as the difference between the maximum and minimum QT interval) and QTcd were calculated using the Bazzet formula at baseline and after six months of CPAP therapy.

RESULTS

Eighteen patients were compliant with nasal CPAP, and mean age was 46.5+/-4.9 years. Patients had high body mass index (BMI: 30.6+/-4.0 kg/m(2)), but there was no change in either BMI or blood pressure after six months. A strong positive correlation was shown between QTcd and AHI (p<0.001, r=0.913). The QTcd at baseline (54.5+/-8.7 ms) significantly decreased after CPAP therapy (35.5+/-4.2 ms, p<0.001), although it did not significantly change in 11 non-compliant patients.

CONCLUSION

In OSA patients without hypertension, CPAP therapy improves the inhomogeneity of repolarization via a significant decrease in QTcd.

Fixed and Autoadjusting Continuous Positive Airway Pressure Treatments Are Not Similar in Reducing Cardiovascular Risk Factors in Patients With Obstructive Sleep Apnea

BACKGROUND

A strong association between obstructive sleep apnea (OSA) and the risk for cardiovascular and cerebrovascular diseases has been reported. Continuous positive airway pressure (CPAP) is the first-line therapy for OSA, able not only to reduce daytime sleepiness but also to improve cardiovascular and metabolic outcomes. Autoadjusting CPAP (APAP), an alternative treatment to CPAP, can reduce OSA symptoms while increasing long-term CPAP compliance without the high costs of CPAP titration. However, no data are available on the effects of APAP on cardiovascular risk factors

METHODS

We performed standard full polysomnography; obtained plasma levels of glucose, insulin, and C-reactive protein (CRP); and measured systolic BP (SBP) and diastolic BP (DBP) in 31 patients with newly diagnosed, severe OSA. After standard CPAP titration, all subjects were randomized to CPAP or APAP treatment. Measurements were obtained at baseline and after 3 months of treatment.

RESULTS

The two groups were similar in terms of age, sex, body mass index (BMI), and severity of OSA. SBP, DBP, heart rate (HR), homeostasis model assessment index (HOMA-IR), and CRP were similar in the two groups. After 3 months of treatment, BMI, HR, and compliance to therapy were also comparable. OSA indexes were significantly reduced in both groups. Significant reductions in SBP, DBP, and HOMA-IR were observed in the CPAP group but not in the APAP group, while CRP plasma levels were similarly reduced.

CONCLUSIONS

Our results suggest that CPAP and APAP, despite significant effects on OSA indexes and symptoms, do not improve cardiovascular risk factors in the same fashion.

Do we neglect women with sleep apnea?

Obstructive sleep apnea (OSA) affects approximately 5% of women and 15% of men in the middle-aged adults, and associated with adverse health outcomes. The prevalence and severity of OSA in women increase across the menopause, as the cardiovascular death and events do. Unfortunately, women with OSA might be under-diagnosed due to circumstances related to the family lifestyle and socio-cultural factors in addition to the different OSA clinical expression. Evaluation of cardiovascular global risk assessment in women with OSA is very important to prevent the high potential cardiovascular morbidity and mortality, since they are poorly informed about cardiovascular disease (CVD). So, we should be aware of the clues suspecting OSA and cardiovascular risk in women admitting to sleep clinics.

Effects of CPAP on left ventricular structure and myocardial performance index in male patients with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) has the potential to cause heart failure. We aimed to determine the effects of nasal continuous positive airway pressure (CPAP) therapy on left ventricular structure and myocardial performance index (MPI) in severe OSA patients.

METHODS

Sixty-seven subjects without any cardiac or pulmonary disease had overnight polysomnography and echocardiography. In 33 males with severe OSA, thickness of interventricular septum (IVS) and posterior wall (LVPW) were measured by M-mode. Left ventricular MPI was calculated as (isovolumic contraction time+isovolumic relaxation time)/aortic ejection time by Doppler.

RESULTS

Eight males were non-compliant with CPAP. Mean age was 47.9+/-8.2 years, and 20 of 25 patients (80.0%) were hypertensive. Patients had high body mass index (BMI: 31.0+/-3.9 kg/m(2)), but there was no change in BMI from baseline after 6 months. Thickness of IVS (11.0+/-1.1mm) and LVPW (11.0+/-1.0mm) at baseline were significantly decreased after 6 months of CPAP therapy (10.5+/-0.9 mm, P<0.001 and 10.4+/-0.7 mm, P<0.0001, respectively). Left ventricular MPI (60.1+/-13.8%) significantly decreased (53.0+/-10.7%, P<0.0001) after CPAP usage.

CONCLUSIONS

In male patients with severe OSA, CPAP therapy significantly decreases left ventricular wall thickness and improves global function even with 6 months of usage.

Effect of CPAP on brachial-ankle pulse wave velocity in patients with OSAHS: An open-labelled study

Pulse wave velocity (PWV) is a good indicator of arterial stiffness and an important predictor of cardiovascular events. Recent studies have revealed that PWV increases in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) and it also correlates with its severity. However, the therapeutic effect of continuous positive airway pressure (CPAP) on PWV remains undetermined. To clarify this point, we started CPAP treatment on 17 OSAHS patients. Brachial-ankle PWV was measured before starting CPAP, and at 2 months and 4 months after the start of CPAP. Before the CPAP treatment, mean brachial-ankle PWV of the patients was 15.6+/-0.6 m/s, and mean Epworth sleepiness scale (ESS) score was 8.6+/-1.0. Brachial-ankle PWV was found to positively correlate with heart rate, systolic and diastolic blood pressures, mean blood pressure, and arousal index. During the study period, the CPAP treatment did not have a significant effect on heart rate, blood pressures and serum total cholesterol levels. However, it significantly improved ESS score at 4 months after the start of CPAP (P=0.001), while it effectively decreased brachial-ankle PWV at 2 months and at 4 months after the start of CPAP (P=0.010 and P=0.027, respectively). The CPAP treatment was shown to decrease brachial-ankle PWV without affecting blood pressures in OSAHS patients. Although the precise mechanism for this effect is unclear, our finding suggests a close relationship between OSAHS and arterial stiffness, while also reemphasizing the clinical importance of CPAP treatment.

Nondipping blood pressure patterns among individuals with essential hypertension: a review of the literature

BACKGROUND

Researchers have discovered that blood pressure (BP) varies in a diurnal manner throughout a 24-hour period, being higher during the day and lower at night. Most people have a dipping BP pattern characterized by a nighttime BP that is 10-20% lower than their daytime BP. Individuals who experience a less than 10% reduction in nighttime BP are described as having a nondipping BP pattern. Although controversial, there is a growing body of evidence suggesting that a nondipping BP pattern is associated with a greater risk of target organ damage among individuals with essential hypertension.

AIM

To review the literature on the most common factors associated with nondipping BP patterns among individuals with essential hypertension.

METHODS

CINAHL (1982-March 2006), PubMed (1950-March 2006) and Cochrane Library (1966-March 2006) databases were searched using the keywords: dipper, dipping, nondipper, nondipping, ambulatory blood pressure monitoring, ABPM, hypertension, essential hypertension, high blood pressure, blood pressure, nocturnal blood pressure, nighttime blood pressure, diurnal blood pressure, and blood pressure patterns. Published studies, abstracts, dissertations as well as the reference lists of retrieved articles were reviewed. Studies were included if they involved subjects with only treated or untreated essential hypertension or those with samples of both nomotensive and treated or untreated essential hypertensive individuals. Additionally, studies needed to evaluate 24-hour, daytime and nighttime BP patterns.

RESULTS

There is some evidence to suggest advanced age, African-American ethnicity, female sex, postmenopausal status, sodium sensitivity, sleep apnea, sleep quality, anger, hostility, depression, stress, social support, and socioeconomic status have an association with nondipping BP patterns.

CONCLUSION

Knowledge of the potential factors associated with an altered nighttime BP pattern is of importance because it can help identify persons at risk for nondipping BP patterns and potential target organ damage. Furthermore, knowledge of these factors associated with a nondipping BP profile will lay the foundation for interventions to prevent/treat alterations in nighttime BP patterns.

Reviews: Diagnosis and Management of Sleep Apnea Syndrome and Restless Legs Syndrome in Dialysis Patients

Sleep complaints are very common in patients with end-stage renal disease (ESRD) and contribute to their impaired quality of life. Both obstructive and central sleep apnea syndromes are reported more often in patients on dialysis than in the general population. Impaired daytime functioning, sleepiness, and fatigue, as well as cognitive problems, are well known in patients with sleep apnea. Increasing evidence supports the pathophysiological role of sleep apnea in cardiovascular disorders, which are the leading cause of death in ESRD patients. Uremic factors may be involved in the pathogenesis of sleep apnea in this patient population and optimal dialysis may reduce disease severity. Furthermore, treatment with continuous positive airway pressure may improve quality of life and may help to manage hypertension in these patients. Secondary restless legs syndrome is highly prevalent in patients on maintenance dialysis. The pathophysiology of the disorder may also involve uremia-related factors, iron deficiency, and anemia, but genetic and lifestyle factors might also play a role. The treatment of restless legs syndrome involves various pharmacologic approaches and might be challenging in severe cases. In this article we review the diagnosis and treatment of sleep apnea and restless legs syndrome, with a focus on dialysis patients. We also briefly review current data regarding sleep problems after transplantation, since these studies may indirectly shed light on the possible pathophysiological role of uremia or dialysis in the etiology of sleep disorders. Considering the importance of sleep disorders, more awareness among professionals involved in the care of patients on dialysis is necessary. Appropriate management of sleep disorders could improve the quality of life and possibly even impact upon survival of renal patients.

The effect of obesity on chronic respiratory diseases: pathophysiology and therapeutic strategies

Sedentary lifestyles and increased pollution brought about by industrialization pose major challenges to the prevention of both obesity and chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, obstructive sleep apnea and obesity hypoventilation syndrome. Obesity has emerged as an important risk factor for these respiratory diseases, and in many instances weight loss is associated with important symptomatic improvement. Moreover, obesity may influence the development and presentation of these diseases. In this article, we review the current understanding of the influence of obesity on chronic respiratory diseases and the clinical management of obesity concurrent with asthma, COPD, obstructive sleep apnea or obesity hypoventilation syndrome.

Effects of CPAP on right ventricular myocardial performance index in obstructive sleep apnea patients without hypertension

OBJECTIVES

Obstructive sleep apnoea (OSA) might cause right ventricular dysfunction and pulmonary hypertension. We aimed to determine the effects of nasal continuous positive airway pressure (CPAP) therapy on right ventricular myocardial performance index (MPI) in OSA patients without hypertension.

METHODS

49 subjects without hypertension, diabetes mellitus, any cardiac and pulmonary disease had overnight polysomnography and echocardiography. In 18 moderate-severe OSA (apnea-hypopnea index > or = 15) patients, right ventricular free wall diameter (RVFWD) was measured by M-mode, and right ventricular MPI was calculated as (isovolumic contraction time+ isovolumic relaxation time) / pulmonary ejection time using Doppler at baseline and after 6 months CPAP therapy.

RESULTS

Mean age was 46.5 +/- 4.9 year. Patients had high body mass index (BMI: 30.6 +/- 4,0 kg/m2), but there was no change in either BMI or blood pressures after 6 months. Right ventricular end-diastolic and end-systolic diameters were in normal limits at baseline, and did not change after CPAP usage. Baseline RVFWD (7.1 +/- 2.1 mm) significantly decreased after CPAP therapy (6.2 +/- 1.7 mm, p < 0.001). 15 of patients (83%) had right ventricular diastolic dysfunction at baseline, and it was completely improved in 11 of them (73%) by CPAP usage. Right ventricular global dysfunction was shown in 11 patients (61%) with a high MPI (62.2 +/- 9.3%) at baseline; and MPI was significantly decreased after CPAP therapy (47.3 +/- 8.4%, p < 0.0001), and it was completely corrected in 4 of them (36%).

CONCLUSION

CPAP therapy significantly decreases RVFWD and improves right ventricular diastolic and global functions (MPI) in OSA patients without hypertension.

Deleterious effects of sleep-disordered breathing on the heart and vascular system

Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing, affecting 5-15% of the population. It is characterized by intermittent episodes of partial or complete obstruction of the upper airway during sleep that disrupts normal ventilation and sleep architecture, and is typically associated with excessive daytime sleepiness, snoring, and witnessed apneas. Patients with obstructive sleep apnea present risk to the general public safety by causing 8-fold increase in vehicle accidents, and they may themselves also suffer from the physiologic consequences of OSA; these include hypertension, coronary artery disease, stroke, congestive heart failure, pulmonary hypertension, and cardiac arrhythmias. Of these possible cardiovascular consequences, the association between OSA and hypertension has been found to be the most convincing. Although the exact mechanism has not been understood, there is some evidence that OSA is associated with frequent apneas causing mechanical effects on intrathoracic pressure, cardiac function, and intermittent hypoxemia, which may in turn cause endothelial dysfunction and increase in sympathetic drive. Therapy with continuous positive airway pressure has been demonstrated to improve cardiopulmonary hemodynamics in patients with OSA and may reverse the endothelial cell dysfunction. Despite the availability of diagnostic measures and effective treatment, many patients with sleep-disordered breathing remain undiagnosed. Therefore, OSA continues to be a significant health risk both for affected individuals and for the general public. Awareness and timely initiation of an effective treatment may prevent potential deleterious cardiovascular effects of OSA.