Continuous positive airway pressure lowers blood pressure in hypertensive patients with obstructive sleep apnea

Summary Question of the study Obstructive sleep apnea (OSA) and hypertension are frequently associated and probably causally related. We investigated the influence of continuous positive airway pressure (CPAP) on blood pressure (BP) in OSA. Patients and Methods Fourty-four patients in whom CPAP-therapy had been successfully applied for treatment of OSA (median apnea-hypopopnea-index [AHI] 57.5/h) were included. Non-invasive 24-hour BP was measured at 15  min intervals before and with CPAP. Results After 1 – 3 days of CPAP, 24-hour systolic and diastolic BP in the hypertensive patients (n = 32) decreased from a median of 141 (129 – 173, 25 % – 75 % interquartile range) mmHg to 136 (118 – 157) mmHg (p = 0.004) and from 90 (80 – 107) mmHg to 88 (77 – 99) mmHg (p = 0.001), respectively, but was unchanged in the normotensives (n = 10). After 4 – 6 months of CPAP, 24-hour systolic and diastolic BP in a hypertensive subgroup (n = 19) decreased from a median of 140 (131 – 142) mmHg to 131 (122 – 143) mmHg (p = 0.01) and from 88 (86 – 94) mmHg to 84 (80 – 87) mmHg (p = 0.02), respectively, but was unchanged in a normotensive subgroup (n = 8). After long-term CPAP, there was a small weight reduction in the hypertensive patients. Subgroup analysis of 13 hypertensives with stable weight confirmed a significant BP-reduction. Conclusions In OSA with associated hypertension, CPAP has a specific BP-lowering effect. This suggests that both disorders are causally related.     

Good long‐term adherence to continuous positive airway pressure therapy in patients with resistant hypertension and sleep apnea

Although adequate adherence is paramount in achieving the beneficial effects of continuous positive airway pressure therapy in patients with obstructive sleep apnea, long‐term adherence and the variables involved in continuous positive airway pressure compliance in patients with resistant hypertension and obstructive sleep apnea are yet unknown. We conducted a prospective, multicentre, observational study in 177 patients recruited from hypertensive units with resistant hypertension confirmed by means of 24‐hr blood pressure monitoring (blood pressure ≥ 130 and/or ≥ 80 mmHg, despite taking at least three antihypertensive drugs or < 130/80 mmHg with > 3 drugs) and obstructive sleep apnea (apnea–hypopnea index ≥ 5 in a respiratory polygraph) who were prescribed continuous positive airway pressure treatment. Good adherence was defined as an average cumulative continuous positive airway pressure use of ≥ 4 hr per night at the end of the follow‐up. A multivariate Cox regression analysis was performed to identify independent predictors of continuous positive airway pressure adherence. Patients were followed for a median of 57.6 (42–72) months after initiating continuous positive airway pressure therapy. At the end of the follow‐up, the median continuous positive airway pressure use was 5.7 (inter‐quartile range 3.9–6.6) hr per night, and 132 patients (74.5%) showed good continuous positive airway pressure adherence. The only baseline variable associated with poor adherence was the presence of previous stroke (hazard ratio 4.00, 95% confidence interval 1.92–8.31). Adequate adherence at 1 month also predicted good adherence at the end of the follow‐up (hazard ratio 14.4, 95% confidence interval 4.94–56). Both variables also predicted adherence at a threshold of 6 hr per night. Our results show that good continuous positive airway pressure adherence is an achievable and feasible goal in patients with resistant hypertension and obstructive sleep apnea. Previous stroke and short‐term adherence predicted long‐term adherence.     

Impact of continuous positive airway pressure (CPAP) on quality of life in patients with obstructive sleep apnea (OSA)

Obstructive sleep apnea is a chronic illness with increasing prevalence. In addition to associated cardiovascular comorbidities, obstructive sleep apnea syndrome has been linked to poor quality of life, occupational accidents, and motor vehicle crashes secondary to excessive daytime sleepiness. Although continuous positive airway pressure is the gold standard for sleep apnea treatment, its effects on quality of life are not well defined. In the current study we investigated the effects of treatment on quality of life using the data from the Apnea Positive Pressure Long‐term Efficacy Study (APPLES), a randomized controlled trial of continuous positive airway pressure (CPAP) versus sham CPAP. The Calgary Sleep Apnea Quality of Life Index (SAQLI) was used to assess quality of life. Overall we found no significant improvement in quality of life among sleep apnea patients after CPAP treatment. However, after stratifying by OSA severity, it was found that long‐term improvement in quality of life might occur with the use of CPAP in people with severe and possibly moderate sleep apnea, and no demonstrable improvement in quality of life was noted among participants with mild obstructive sleep apnea.     

Dose‐dependent effects of continuous positive airway pressure for sleep apnea on weight or metabolic function: Individual patient‐level clinical trial meta‐analysis

Therapeutic‐continuous positive airway pressure seems to increase weight compared with placebo‐continuous positive airway pressure. It is not known whether weight gain with therapeutic‐continuous positive airway pressure dose is dependent or whether it causes metabolic dysfunction. Data synthesis of three randomised placebo‐continuous positive airway pressure‐controlled trials (2–3 months) was performed to test whether there is a dose‐dependent effect of continuous positive airway pressure on weight. Fasting glucose, insulin, insulin resistance (homeostatic model assessment), lipids and visceral abdominal fat were also tested to determine any effect on metabolic function. Mixed‐model analysis of variance was used to quantify these effects. One‐hundred and twenty‐eight patients were analysed. Overall there was a small increase in weight with therapeutic‐continuous positive airway pressure use compared with placebo‐continuous positive airway pressure (difference: 1.17 kg; 0.37–1.97, p = 0.005), which was greater with high‐use therapeutic‐continuous positive airway pressure compared with high‐use placebo‐continuous positive airway pressure (1.45 kg; 0.10–2.80, p = 0.04). Continuous positive airway pressure use as a continuous variable was also significantly associated with weight change in continuous positive airway pressure users (0.30 kg hr^?1 night^?1; 0.04–0.56, p = 0.001), but not in placebo users (0.04 kg hr^?1 night^?1; ?0.22 to 0.26, p = 0.76). Neither therapeutic‐continuous positive airway pressure nor the dose of therapeutic‐continuous positive airway pressure caused any changes to metabolic outcomes. The weight gain effects of medium‐term therapeutic‐continuous positive airway pressure appear modest and are not accompanied by any adverse metabolic effects.     

Effects of continuous positive airway pressure treatment on aortic stiffness in patients with resistant hypertension and obstructive sleep apnea: A randomized controlled trial

Resistant hypertension (RHT) is associated with obstructive sleep apnea (OSA) and increased aortic stiffness, measured by carotid‐femoral pulse wave velocity (cf‐PWV). We aimed to evaluate in a randomized controlled trial, the effect of Continuous positive airway pressure (CPAP) treatment on cf‐PWV in comparison with a control group in patients with RHT and moderate‐severe OSA. One‐hundred and sixteen patients were randomized to 6‐month CPAP treatment (56 patients) or no therapy (60 patients), while keeping their antihypertensive treatment unchanged. Carotid‐femoral pulse wave velocity was performed at the beginning and end of the 6‐month period. Intention‐to‐treat intergroup differences in cf‐PWV changes were assessed by a generalized mixed‐effects model with the allocation group as a fixed factor and adjusted for age, sex, changes in mean arterial pressure and the baseline cf‐PWV values. Subgroup sensitivity analyses were performed, excluding patients with low CPAP adherence and low cf‐PWV at baseline. CPAP and control groups had similar clinic‐laboratorial characteristics. Patients had a mean cf‐PWV of 9.4 ± 1.6 m/s and 33% presented cf‐PWV > 10 m/s. During treatment, the control group had a mean increase in cf‐PWV of +0.43 m/s (95% confidence interval [CI], +0.14 to +0.73 m/s; p = .005), whereas the CPAP group had a mean increase of +0.03 m/s (95% CI, ?0.33 to +0.39 m/s; p = .87), resulting in a mean difference in changes between CPAP and control of ?0.40 m/s (95% CI, ?0.82 to +0.02 m/s; p = .059). Subgroup analyses did not change the results. In conclusion, a 6‐month CPAP treatment did not reduce aortic stiffness, measured by cf‐PWV, in patients with RHT and moderate/severe OSA, but treatment may prevent its progression, in contrast to no‐CPAP therapy.     

Periodic limb movements and obstructive sleep apneas before and after continuous positive airway pressure treatment

Periodic limb movements during sleep (PLMS) and obstructive sleep apnea syndrome (OSAS) are two common sleep disorders. The similarity in periodicity of periodic limb movements (PLMs) and obstructive sleep apneas (OSAs) led us to hypothesize the existence of a common central generator responsible for the periodicity of both OSAs and PLMs. In order to test this hypothesis, we compared apnea periodicity before continuous positive airway pressure (CPAP) treatment with PLMs periodicity during CPAP treatment in 26 OSA patients, consecutively recorded and treated in our sleep laboratory. The investigation on CPAP was performed twice, once during the initial evaluation and once during a follow-up evaluation after 3 months of home treatment with CPAP. Our results showed that, in this sample, 16 patients out of 26 had an association of OSAS and PLMS, defined as the occurrence of at least 5 PLMs per hour of sleep. The mean apnea interval - measured as the time between the beginning of two successive apneas - was 43.1 s (+/-15.2, SD) and the mean PLM interval - calculated in the same way - was 29.6 s (+/-15.2) during the baseline night, 28.5 s (+/-15.7) during the first CPAP night, and 29.8 s (+/-14.8) during the second CPAP night. Thus, the periodicity of the two phenomena (apneas and PLMs) was different, both before and after CPAP treatment (P< 0.05). When considering the interval between the end of an event (apnea or PLM) and the beginning of the next one the mean apnea interval was 19.5 s (+/-11. 6), and the mean PLM interval was 28.1 s (+/-15.3) during the untreated night, 26.6 s (+/-16) during the first CPAP night and 27.9 s (+/-15) during the second CPAP night. The shortening of apnea intervals with this method of measuring intervals reflects the longer duration of apneas as compared to PLMs. Again the intervals between PLMs were not different between each other but the intervals between apneas were different from the intervals between PLMs (P< 0. 05) These results show that the periodicity of PLMs is different from that of OSAs, suggesting that sleep apneas and PLMs are not generated by a common central generator.     

Predictors of continuous positive airway pressure use during the first week of treatment

This study aimed to identify pre‐treatment and immediate early treatment factors predicting continuous positive airway pressure (CPAP) use during the first week of therapy, when the pattern of non‐adherence is established. Four domains of potential predictors were examined: pre‐treatment demographic and clinical factors, patients’ perceived self‐efficacy, treatment delivery (mask leak and bothering side effects) and immediate disease reduction (residual respiratory events and flow limitation). The Autoset? Clinical System objectively documented daily CPAP use, mask leak, residual respiratory events and flow limitation. Ninety‐one CPAP‐naive patients with newly diagnosed obstructive sleep apnea were followed for 1 week after treatment initiation. Mean CPAP daily use during the first week was 3.4 ± 2.7 h, with significantly lower use observed in black than non‐black participants (2.7 versus 4.4 h, respectively, P = 0.002). Less intimacy with partners caused by CPAP was the only treatment side effect correlated with CPAP use (r = ?0.300, P = 0.025). Reduced CPAP use during the first week was associated simultaneously with being black, higher residual apnea–hypopnea index and the treatment side effect of less intimacy with partners. The three factors together accounted for 25.4% of the variance in the CPAP use (R² = 0.254, P < 0.01). These data suggest the need to assess the impact of CPAP on intimacy and troubleshooting aspects of the treatment that interfere with sexual relationships. Assessing the presence of residual respiratory events may be important in promoting CPAP adherence. The association of race and CPAP use needs to be explored further by including more socioeconomic information.     

Continuous positive airway pressure may improve hypertension in patients with obstructive sleep apnea-hypopnea syndrome by inhibiting inflammation and oxidative stress

IntroductionThe work was designed to investigate the effect of continuous positive airway pressure (CPAP) on hypertension in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients and to elucidate the underlying mechanisms.MethodsWe examined the effect of CPAP on blood pressure and biomarkers reflecting inflammation and oxidative stress, and investigated the correlation between changes in blood pressure and the biomarkers.ResultsCPAP significantly improved clinic, ambulatory and home blood pressure (p < 0.05). The hypotensive effect of CPAP was positively correlated with the decrease of interleukin-6, C-reactive protein, NADPH oxidase and malonaldehyde.ConclusionsCPAP has a significant antihypertensive effect on OSAHS patients, especially nocturnal hypertension, possibly by counteracting inflammation and oxidative stress.     

持续正压通气对睡眠呼吸暂停低通气综合征患者血浆脂类水平的影响

目的 探讨持续正压通气（CPAP）治疗阻塞性睡眠呼吸暂停低通气综合征（OSAHS）对血脂水平的影响。方法 对23例OSAS患者经CPAP治疗前及治疗后（4周、12周及1年）进行血脂水平、体重及多导睡眠图的检测（PSG）。结果 OSAHS患者经CPAP治疗后血清总胆固醇（TC）、甘油三脂（TG）、低密度脂蛋白胆固醇（LDL-CH）、载脂蛋白-B（Apo-B）出现逐渐下降的趋势（治疗前分别为：7．45mmol／L，3．49mmol／L，3．75mmol／L，1．36g／L；治疗4周时分别为：7．36mmol／L，3．26mmol／L，3．57mmol／L，1．33g／L；治疗12周时分别为：7．23mmol／L，3．20mmol／L，3．52mmol／L，1．32g／L；治疗1年时分别为：5．38mmol／L，2．74mmol／L，3．14mmol／L，1．02g／L）。而高密度脂蛋白胆固醇（HDL-CH）和载脂蛋白-A（Apo-A）出现逐渐升高趋势（治疗前分别为：1．04mmol／L，0．84g／L；治疗4周时分别为：1．05mmol／L，0．88g／L；治疗12周时分别为：1．12mmol／L，0．91g／L；治疗1年时分别为：1．41mmol／L，1．20g／L），这种升高和下降的趋势在治疗1年后差异有统计学意义（P〈0．05），但在治疗12周前血脂水平变化差异无统计学意义（P〉0．05）。经1年治疗后体重指数明显下降，从治疗前（30．1±3．3）kg／m^2下降到（27．6±6．1）kg／m^2（P〈0．05）。结论 OSAHS患者长期使用CPAP治疗可以有效改善其血脂水平代谢。     

Efficacy of continuous positive airway pressure treatment on 5‐year survival in patients with ischaemic stroke and obstructive sleep apnea: a randomized controlled trial

The main purpose of the present analysis is to assess the influence of introducing early nasal continuous positive airway pressure (nCPAP) treatment on cardiovascular recurrences and mortality in patients with a first‐ever ischaemic stroke and moderate–severe obstructive sleep apnea (OSA) with an apnea–hypopnea index (AHI) ≥20 events h^?1 during a 5‐year follow‐up. Patients received conventional treatment for stroke and were assigned randomly to the nCPAP group (n = 71) or the control group (n = 69). Cardiovascular events and mortality were registered for all patients. Survival and cardiovascular event‐free survival analysis were performed after 5‐year follow‐up using the Kaplan–Meier test. Patients in the nCPAP group had significantly higher cardiovascular survival than the control group (100 versus 89.9%, log‐rank test 5.887; P = 0.015) However, and also despite a positive tendency, there were no significant differences in the cardiovascular event‐free survival at 68 months between the nCPAP and control groups (89.5 versus 75.4%, log‐rank test 3.565; P = 0.059). Early nCPAP therapy has a positive effect on long‐term survival in ischaemic stroke patients and moderate–severe OSA.     

Determinants of depressive mood in coronary artery disease patients with obstructive sleep apnea and response to continuous positive airway pressure treatment in non‐sleepy and sleepy phenotypes in the RICCADSA cohort

We explored determinants of depressive mood in adults with coronary artery disease and obstructive sleep apnea and response to positive airway pressure treatment in sleepy and non‐sleepy phenotypes. In this secondary analysis of the RICCADSA trial conducted in Sweden, 493 cardiac patients with obstructive sleep apnea (n = 386) or no obstructive sleep apnea (n = 107) with complete Epworth Sleepiness Scale and Zung Self‐rating Depression Scale questionnaires were included. Sleepy (Epworth Sleepiness Scale ≥10) versus non‐sleepy (Epworth Sleepiness Scale <10) patients with depressive mood (Zung Self‐rating Depression Scale score ≥50) were evaluated after 3 and 12 months of positive airway pressure treatment. In all, 133 patients (27.0%) had depressive mood (29.3% of obstructive sleep apnea versus 18.7% of no obstructive sleep apnea; p = 0.029), with a higher percentage among the sleepy phenotype (36.9% versus 24.5%; p = 0.009). In multivariate analysis, depressive mood was significantly associated with female sex, body mass index and Epworth Sleepiness Scale. Among 97 obstructive sleep apnea patients with depressive mood at baseline, there was a significant reduction in the scores at follow‐up both in the sleepy and non‐sleepy patients allocated to positive airway pressure treatment, whereas no significant changes were observed in the untreated group (p = 0.033). The device use (hr/night) predicted improvement in mood (odds ratio, 1.33; 95% confidence interval, 1.10–1.61; p = 0.003) adjusted for age, female sex, body mass index, left ventricular ejection fraction, apnea–hypopnea index and delta Epworth Sleepiness Scale score. We conclude that obstructive sleep apnea was associated with depressive mood in adults with coronary artery disease. Treatment with positive airway pressure improved mood in both phenotypes, independent of the confounding factors.     

Carbonic anhydrase,obstructive sleep apnea and hypertension: Effects of intervention

Whole blood carbonic anhydrase activity (CAa) is increased in patients with obstructive sleep apnea (OSA). Our study investigated the influence of positive airway pressure (PAP) or CA inhibitor acetazolamide (ACT) therapy on CAa, OSA and blood pressure. Thirty‐three OSA patients (21 hypertensive, body mass index (BMI) 37 ± 7 kg/m² and apnea–hypopnea index (AHI) of 47 ± 31 events/hr) were followed‐up after PAP treatment (compliance, 4.7 ± 1.5 hr/day; duration, median 6 [IQR 6,6] months) (Cohort A). A second OSA Cohort (B) contained nine hypertensive patients (BMI, 29 ± 4 kg/m²; AHI, 39 ± 20 events/hr) with 2‐week treatment of ACT, PAP or ACT + PAP in an open crossover study. CAa was assessed at baseline and at the end of each treatment period. In Cohort A, baseline CAa was higher in hypertensive, compared with normotensive, patients (1,033 ± 204 versus 861 ± 201 units, p = .028). PAP treatment reduced systolic/diastolic blood pressure but not CAa (?9 ± 11/?5 ± 7 mmHg and ?20 ± 289 units, p < .001, <.001 and .70). In Cohort B, blood pressure was reduced in both ACT‐treated groups (?10 ± 10/?5 ± 7 mmHg, p = .043 and .019; and ?5 ± 5/?13 ± 13 mmHg, p < .001 and .009). AHI was reduced in both groups: ACT only, ?17 ± 9 events/hr p = .001; and ACT + PAP, ?39 ± 19 events/hr, p < .001. PAP did not change CAa (p = .98) but activity tended to decrease after ACT with or without PAP (p = .081 and .056). CAa is elevated in hypertensive OSA patients. Long‐term PAP reduced blood pressure without affecting CAa. ACT reduced blood pressure and CAa. Increased CAa may constitute a physiological characteristic in OSA, contributing to comorbid hypertension.     

A mobile,web‐based system can improve positive airway pressure adherence

SleepMapper is a mobile, web‐based system that allows patients to self‐monitor their positive airway pressure therapy, and provides feedback and education in real time. In addition to the usual, comprehensive support provided at our clinic, we gave the SleepMapper to 30 patients initiating positive airway pressure. They were compared with patients initiating positive airway pressure at our clinic without SleepMapper (controls) to determine whether SleepMapper affected adherence. A total of 61 patients had polysomnographic and adherence data analysed, 30 were given SleepMapper and 31 received our standard of care. The two groups were well matched at baseline to include no significant differences in age, apnea–hypopnea index, percentage receiving split‐night polysomnographs and starting pressures. Patients in the control group received significantly more non‐benzodiazepine sedative hypnotics the night of their polysomnography and during positive airway pressure initiation. At 11 weeks, patients in the SleepMapper group had a greater percentage of nights with any use (78.0 ± 22.0 versus 55.5 ± 24.0%; P < 0.001) and >4 h positive airway pressure use (78.0 ± 22.0 versus 55.5 ± 24.0%; P = 0.02). There was a trend toward more patients in the SleepMapper group achieving >4 h of use for at least 70% of nights [9/30 (30%) versus 3/31 (9.7%); P = 0.06]. In multivariate linear regression, the SleepMapper remained significantly associated with percentage of nights >4 h positive airway pressure use (β coefficient = 0.18; P = 0.02). Added to our usual, comprehensive programme to maximize positive airway pressure adherence in new users, the SleepMapper was independently associated with an 18% increase in nights >4 h of use.     

Effects of obesity on the association between long‐term sleep apnea treatment and changes in interleukin‐6 levels: the Icelandic Sleep Apnea Cohort

The aim of this study was to evaluate changes in interleukin (IL)‐6 and soluble IL‐6 receptor levels in obstructive sleep apnea patients and assess the role of positive airway pressure treatment and obesity on these changes. A total of 309 newly diagnosed subjects with sleep apnea from the Icelandic Sleep Apnea Cohort were referred for treatment and reassessed at a 2‐year follow‐up. Full treatment was defined objectively as use ≥4 h day^?1 and ≥20 days month^?1. At the 2‐year follow‐up, there were 177 full users, 44 partial users and 88 non‐users. The mean change in biomarker levels from baseline to the 2‐year follow‐up was assessed in a primary model that included adjustment for baseline biomarker levels, baseline body mass index and change in body mass index, as well as after adjustment for numerous relevant covariates. No significant overall difference in IL‐6 level change was found among full, partial and non‐users. However, in severely obese patients (body mass index ≥35), a significant increase in IL‐6 levels during the 2‐year period was found in partial and non‐users, compared to no change in full users. Results were attenuated in a smaller propensity score matched subsample, although similar trends were observed. No differences were found in soluble IL‐6 receptor levels between full users and non‐users, after adjustment for confounders. In conclusion, among untreated obese sleep apnea patients, IL‐6 levels increase substantially during 2 years, while adherence to positive airway pressure treatment may prevent further increases in this inflammatory biomarker.     

Nasal pillows as an alternative interface in patients with obstructive sleep apnoea syndrome initiating continuous positive airway pressure therapy

Side‐effects directly due to the nasal mask are common in patients with obstructive sleep apnoea syndrome (OSAS) commencing continuous positive airway pressure (CPAP). Recently, nasal pillows have been designed to overcome these issues. Limited evidence exists of the benefits and effectiveness of these devices. Twenty‐one patients (19 male, 49 ± 10 years) with the established diagnosis of OSAS [apnoea/hypopnoea index (AHI): 52 ± 22] and who had a successful CPAP titration were commenced on CPAP therapy (10 ± 2 cmH2O), and randomized to 4 weeks of a nasal pillow (P) and a standard nasal mask (M) in a crossover design. Outcome measures were objective compliance, AHI, quality of life, Epworth Sleepiness Score (ESS) and CPAP side‐effects. There was no difference in compliance (M versus P: 5.1 ± 1.9 h versus 5.0 ± 1.7 h; P = 0.701) and AHI (2.6 ± 2.7 versus 3.0 ± 2.9; P = 0.509). Quality of life and ESS improved with CPAP, but there was no difference in the extent of improvement between both devices. Usage of nasal pillows resulted in less reported pressure on the face and more subjects found the nasal pillow the more comfortable device. However, there was no clear overall preference for either device at the end of the study (mask = 57%, pillow = 43%; P = 0.513). The applied CPAP pressure did not correlate with compliance, AHI and ESS. Furthermore, no differences in outcome parameters were noted comparing groups with CPAP pressure <10 and ≥10 cm H₂O. Nasal pillows are equally effective in CPAP therapy, but do not generally lead to improved compliance.     

Usefulness of cardiac parasympathetic index in CPAP‐treated patients with obstructive sleep apnea: A preliminary study

Cardiac autonomic indexes, including cardiac parasympathetic index and cardiac sympathetic index, have been reported to accurately identify patients with sleep disorders such as obstructive sleep apnea. Our study aimed to assess cardiac autonomic indexes in patients with obstructive sleep apnea before and during a single full‐night continuous positive airway pressure therapy using a combined approach. Our simultaneous heart rate variability‐polysomnographic study included 16 never‐treated obstructive sleep apnea patients. Two patients dropped out. Patients underwent combined recordings in two consecutive days, at baseline and during a single full‐night of acute continuous positive airway pressure treatment. We calculated cardiac parasympathetic index and cardiac sympathetic index as night/day ratio for high‐frequency and low‐frequency heart rate variability spectral components, respectively. Continuous positive airway pressure treatment significantly reduced cardiac autonomic indexes values in comparison with baseline values (cardiac parasympathetic index: p < .0001; cardiac sympathetic index: p = .001). After acute continuous positive airway pressure treatment, the percentage of decrease of cardiac parasympathetic index was greater than that of cardiac sympathetic index (51.02 ± 15.72 versus 34.64 ± 26.93). A positive statistical correlation was also found between decrease of cardiac parasympathetic index and decrease of apnea–hypopnea index after continuous positive airway pressure (p < .001). This study improves the knowledge on cardiac autonomic modulation during acute continuous positive airway pressure therapy in obstructive sleep apnea. Our results demonstrate that both autonomic indexes decreased significantly after a single‐night of acute continuous positive airway pressure therapy. Cardiac parasympathetic index more than cardiac sympathetic index was related to decrease of apnea–hypopnea index after continuous positive airway pressure therapy, thus representing a potential help in everyday clinical practice.