Chronic apnea during REM sleep increases arterial pressure and sympathetic modulation in rats

Respiratory Distress Caused by Neoplastic Upper Respiratory Tract Obstructions in 2 Pet Rats (Rattus norvegicus domestica)

Respiratory disease is one of the primary reasons for pet owners to seek veterinary attention for their rats. While chronic respiratory disease complex is most often responsible for respiratory signs in pet rats and is well characterized, upper respiratory obstructive disease has been rarely reported in the literature. This report describes 2 pet fancy rats (Rattus norvegicus domestica) presenting with a several day history of progressive respiratory signs that were minimally responsive to supportive therapies, including antibiotics, nonsteroidal anti-inflammatories, and fluid and oxygen support. Survey radiographs were performed under sedation in both cases. In the first case, no cause for the clinical signs could be identified, in part due to suboptimal radiographic positioning, although severe aerophagia was noted. In the second case, cervical tracheal luminal narrowing and increased soft tissue opacity along the walls of the trachea were identified. Both rats declined while under sedation, resulting in cardiopulmonary arrest in the first case and humane euthanasia in the second. On necropsy, the first case had a oropharyngeal squamous cell carcinoma originating from the Zymbal's gland, which was obstructing the larynx. The second case had an intra-luminal tracheal mass obstructing the airway. This was mostly likely B-cell lymphoma or a plasma cell tumor, although definitive diagnosis was unable to be obtained. For future such cases empiric management of respiratory disease in rats with antimicrobials, anti-inflammatories, and supportive care is often appropriate based on the high prevalence of infectious agents, however, other noninfectious causes should be considered, such as neoplastic processes leading to upper airway obstructive disease and diagnostic imaging may be indicated.

Sleep fragmentation during rapid eye movement sleep and hypertension in obstructive sleep apnea

OBJECTIVE

Sleep fragmentation determined by repetitive arousals from sleep in obstructive sleep apnea (OSA) is associated with hypertension. We aimed to quantify the independent association of arousals during rapid eye movement (REM)/non-rapid eye movement (NREM) sleep with prevalent hypertension.

METHODS

We included adults with 4 h of total sleep time and at least 30 min of REM sleep obtained from overnight in-laboratory polysomnography. Logistic regression models were fitted to explore the association between arousals during REM/NREM sleep and prevalent hypertension. All models controlled for OSA metrics and arousals during NREM/REM sleep, either by statistical adjustment or by stratification.

RESULTS

The sample comprised of 11 643 patients, of which 10 055 were OSA patients. Fully adjusted models demonstrated significant dose-relationships between arousal index during REM sleep (AI-REM) and prevalent hypertension (P trend = 0.002). The higher relative odds of prevalent hypertension were most evident with AI-REM > 40 events/h. In OSA patients with arousal index during NREM sleep (AI-NREM) <15 events/h, every10-unit increase in the AI-REM was associated with 18% higher odds of hypertension (odds ratio, 1.18; 95% confidence interval, 1.11-1.27) in OSA. On the contrary, AI-NREM was not a significant predictor of hypertension in any of the models.

CONCLUSIONS

Our findings indicate that arousals during REM sleep are associated with prevalent hypertension. This is clinically relevant because treatment of OSA is often limited to the first half of the sleep period leaving most of sleep fragmentation during REM sleep untreated.

Effects of Continuous Positive Airway Pressure Therapy on Nocturnal Blood Pressure Fluctuation Patterns in Patients with Obstructive Sleep Apnea

This retrospective study was designed to evaluate the effects of continuous positive airway pressure (CPAP) therapy, a well-established treatment for obstructive sleep apnea (OSA), on nocturnal blood pressure fluctuations (NBPFs) during rapid eye movement (REM) and non-REM sleep, and to evaluate the NBPF patterns in patients with OSA. We included 34 patients with moderate-to-severe OSA who underwent polysomnography using pulse transit time before and at 3−6 months after CPAP therapy. Nocturnal BP and NBPF frequency in REM and non-REM sleep were investigated, as well as NBPF pattern changes after receiving CPAP therapy. CPAP therapy resulted in significant reductions in the apnea−hypopnea index (AHI), arousal index, nocturnal systolic and diastolic BP, and NBPF frequency in REM and non-REM sleep (all p < 0.01). A higher AHI before CPAP resulted in lower nocturnal systolic BP (r = 0.40, p = 0.019) and NBPFs (r = 0.51, p = 0.002) after CPAP. However, 58.8% of patients showed no change in NBPF patterns with CPAP therapy. CPAP therapy significantly improved almost all sleep-related parameters, nocturnal BP, and NBPF frequency in REM and non-REM sleep periods, but NBPF patterns showed various changes post-CPAP therapy. These results suggest that factors other than OSA influence changes in NBPF patterns.

Nocturnal Blood Pressure Fluctuations in Patients with Rapid Eye Movement-Related Obstructive Sleep Apnea

Rapid eye movement-related obstructive sleep apnea (REM-related OSA) is a polysomnographic phenotype. Nocturnal blood pressure (BP) fluctuations remain unclear in patients with REM-related OSA. We studied 27 patients with REM-related OSA, categorized as having REM-apnea-hypopnea index (REM-AHI) ≥ 5/h, REM-AHI/non-REM-AHI ≥ 2, and non-REM-AHI < 15/h. Beat-to-beat systolic BP (SBP) variability and nocturnal SBP fluctuation patterns using pulse transit time (PTT) were investigated. The maximum increase and average nocturnal SBP were significantly higher in males than in females (p = 0.003 and p = 0.008, respectively). The rate of non-dipping patterns in nocturnal SBP fluctuations was 63% in all patients (males, 70%; females, 50%). Epworth Sleepiness Scale (ESS) and Self-rating Depression Scale (SDS) scores in females were higher than those in males (8.4 ± 6.1 vs. 13.4 ± 5.4 points, p = 0.04; 43.8 ± 7.9 vs. 52 ± 11.6 points, p = 0.04, respectively). A high proportion of patients with REM-related OSA had a non-dipping pattern. Using PPT, we observed that in patients with REM-related OSA, SBP variability was greater in males. Despite clinical symptoms being slightly more severe in females, nocturnal SBP fluctuations should be considered in male patients with REM-related OSA.