Impact of nocturnal hemodialysis on the variability of heart rate and duration of hypoxemia during sleep

BACKGROUND: Nocturnal hemodialysis (NHD) alleviates uremia-related sleep apnea, a condition characterized by increased sympathetic activity and diminished heart rate (HR) variability. We tested the hypothesis that NHD reduces both hypoxemia and sympathetic neural contributions to HR variability during sleep. METHODS: Episodes of apnea and hypopnea and the duration of nocturnal hypoxemia during sleep were determined in 9 end-stage renal disease (ESRD) patients (age: 44 +/- 2) (mean +/- SEM) before and after conversion from conventional hemodialysis (CHD) to NHD, and in 10 control subjects (age: 45 +/- 3) with normal renal function and without sleep apnea. Low frequency (LF) (0.05-0.15 Hz) and high frequency (HF) (0.15-0.5 Hz) HR spectral power during stage 2 sleep was calculated (Fast Fourier transformation). Patients were studied 4 times (1 day before and on the night after their CHD session) and 6-15 months after conversion to NHD, while receiving NHD and on a non-dialysis night. RESULTS: NHD decreased the frequency of apnea and hypopnea (from 29.7 +/- 9.3 to 8.2 +/- 2.0 episodes per hour, P= 0.02), and duration of nocturnal hypoxemia (from 13.9 +/- 5.2 to 2.6 +/- 1.9% of total sleep time, P= 0.02). As CHD recipients, ESRD patients had faster nocturnal heart rates (79 +/- 2 vs. 58 +/- 1 min-1, P= 0.03) and lower HF (vagal) (78 +/- 27 vs. 6726 +/- 4556 ms2, P= 0.001) spectral power than control subjects. After conversion to NHD, HR fell (from 79 +/- 2 to 66 +/- 1 min-1, P= 0.03) and HF power increased (from 78 +/- 27 to 637 +/- 139 ms2, P= 0.001). The HF/HF+LF ratio, an index of vagal HR modulation, was lower during CHD (0.16 +/- 0.03 vs. 0.42 +/- 0.05 in control subjects, P < 0.05) and increased (to 0.45 +/- 0.05, P < 0.001) after conversion to NHD. The LF/HF ratio, a representation of sympathetic HR modulation, which was significantly higher during CHD than in control subjects (2.77 +/- 0.82 vs. 0.71 +/- 0.11, P < 0.05), was also normalized by NHD (0.74 +/- 0.12, P < 0.05, compared with CHD). CONCLUSION: Higher heart rates and impaired vagal and augmented sympathetic HR modulation during sleep in ESRD patients are normalized by NHD. Potential mechanisms for these observations include attenuation of surges in sympathetic outflow elicited by apnea and hypoxia during sleep, normalization of nocturnal breathing patterns that influence HRV, and removal, by increased dialysis, of a sympatho-excitatory stimulus of renal origin.     

Sleep apnea and daytime sleepiness in end-stage renal disease

Sleep disorders are common in patients with end-stage renal disease (ESRD). The prevalence of sleep apnea is 10 times greater in patients with ESRD than in the general population. Although sleep apnea is not improved by conventional modes of dialysis, it is corrected by nocturnal hemodialysis, which provides a new and unique model to study its pathophysiology in this patient population. In addition to causing sleep disruption and impairment of daytime function, sleep apnea may also increase the cardiovascular morbidity and mortality that is commonly found in patients with ESRD. "Pathological" daytime sleepiness is found in 50% of patients with ESRD. Although its pathogenesis has been related both to sleep apnea and periodic limb movements, it has also been attributed to a variety of metabolic factors, including the severity of uremia. Further research is required to evaluate the impact of sleep disorders on the clinical outcome of patients with ESRD.     

CO2 Pneumoperitoneum modifies the inflammatory response to sepsis

OBJECTIVE: To analyze the effect of CO2 pneumoperitoneum on the inflammatory response induced by sepsis during laparoscopy. SUMMARY BACKGROUND DATA: A growing body of evidence challenges the once generally accepted notion that smaller incisions alone account for the observed benefits of the laparoscopic approach. Furthermore, laparoscopic surgery is now being applied to a broad spectrum of patients, including those in whom the inflammatory response is ignited. Delineation of the effects of CO2 pneumoperitoneum on the inflammatory response induced by sepsis is needed. METHODS: Sepsis was induced in rats by cecal ligation and puncture (CLP) performed either open or laparoscopically using CO2 or helium as insufflation gases. Animals were killed 24 hours postoperatively, at which time whole blood was collected for complete blood cell counts and livers were harvested for analysis of hepatic expression of the rat acute phase genes alpha2-macroglobulin and beta-fibrinogen. RESULTS: Laparoscopic CLP using CO2 resulted in significantly reduced hepatic expression of the rat acute phase gene alpha2-macroglobulin compared to both laparoscopic CLP using helium and open CLP. Hepatic expression of another rat acute phase gene, beta-fibrinogen, paralleled that of alpha2-macroglobulin and was significantly reduced following laparoscopic CLP using CO2 compared to laparoscopic CLP using helium. Total white blood cell and neutrophil counts following CLP were both significantly higher when CLP was performed laparoscopically using CO2 than when CLP was performed open or laparoscopically using helium. CONCLUSIONS: Intra-abdominal CO2 present during laparoscopy attenuates the acute phase inflammatory response associated with perioperative sepsis.     

Sleep in the critically ill patient

The sleep of intensive care unit (ICU) patients is remarkably disrupted. Several studies, employing both subjective and objective measures of sleep quality, have demonstrated that critically ill patients exhibit severe sleep fragmentation and reduced restorative sleep, particularly a suppression of rapid eye movement (REM) sleep. The cause of sleep disruption in the ICU appears to be multifactorial and includes both the patients' acute and chronic illnesses and factors that are unique to the ICU environment. Noise has been a significant focus of investigation, and the effects of medications, light, and patient-care activities have also been examined. Several questions remain to be answered so that caregivers can improve sleep in ICU patients, including the relative contribution of different sleep-disrupting factors and possible changes in patient susceptibility to these factors over time.     

The Effects on Health Behavior and Health Outcomes of Internet-Based Asynchronous Communication Between Health Providers and Patients With a Chronic Condition: A Systematic Review

Background

In support of professional practice, asynchronous communication between the patient and the provider is implemented separately or in combination with Internet-based self-management interventions. This interaction occurs primarily through electronic messaging or discussion boards. There is little evidence as to whether it is a useful tool for chronically ill patients to support their self-management and increase the effectiveness of interventions.

Objective

The aim of our study was to review the use and usability of patient-provider asynchronous communication for chronically ill patients and the effects of such communication on health behavior, health outcomes, and patient satisfaction.

Methods

A literature search was performed using PubMed and Embase. The quality of the articles was appraised according to the National Institute for Health and Clinical Excellence (NICE) criteria. The use and usability of the asynchronous communication was analyzed by examining the frequency of use and the number of users of the interventions with asynchronous communication, as well as of separate electronic messaging. The effectiveness of asynchronous communication was analyzed by examining effects on health behavior, health outcomes, and patient satisfaction.

Results

Patients’ knowledge concerning their chronic condition increased and they seemed to appreciate being able to communicate asynchronously with their providers. They not only had specific questions but also wanted to communicate about feeling ill. A decrease in visits to the physician was shown in two studies (P=.07, P=.07). Increases in self-management/self-efficacy for patients with back pain, dyspnea, and heart failure were found. Positive health outcomes were shown in 12 studies, where the clinical outcomes for diabetic patients (HbA1c level) and for asthmatic patients (forced expiratory volume [FEV]) improved. Physical symptoms improved in five studies. Five studies generated a variety of positive psychosocial outcomes.

Conclusions

The effect of asynchronous communication is not shown unequivocally in these studies. Patients seem to be interested in using email. Patients are willing to participate and are taking the initiative to discuss health issues with their providers. Additional testing of the effects of asynchronous communication on self-management in chronically ill patients is needed.     

Yohimbine Depresses Excitatory Transmission in BNST and Impairs Extinction of Cocaine Place Preference Through Orexin-Dependent,Norepinephrine-Independent Processes

The alpha2 adrenergic receptor (α₂-AR) antagonist yohimbine is a widely used tool for the study of anxiogenesis and stress-induced drug-seeking behavior. We previously demonstrated that yohimbine paradoxically depresses excitatory transmission in the bed nucleus of the stria terminalis (BNST), a region critical to the integration of stress and reward pathways, and produces an impairment of extinction of cocaine-conditioned place preference (cocaine-CPP) independent of α₂-AR signaling. Recent studies show yohimbine-induced drug-seeking behavior is attenuated by orexin receptor 1 (OX₁R) antagonists. Moreover, yohimbine-induced cocaine-seeking behavior is BNST-dependent. Here, we investigated yohimbine-orexin interactions. Our results demonstrate yohimbine-induced depression of excitatory transmission in the BNST is unaffected by alpha1-AR and corticotropin-releasing factor receptor-1 (CRFR₁) antagonists, but is (1) blocked by OxR antagonists and (2) absent in brain slices from orexin knockout mice. Although the actions of yohimbine were not mimicked by the norepinephrine transporter blocker reboxetine, they were by exogenously applied orexin A. We find that, as with yohimbine, orexin A depression of excitatory transmission in BNST is OX₁R–dependent. Finally, we find these ex vivo effects are paralleled in vivo, as yohimbine-induced impairment of cocaine-CPP extinction is blocked by a systemically administered OX₁R antagonist. These data highlight a new mechanism for orexin on excitatory anxiety circuits and demonstrate that some of the actions of yohimbine may be directly dependent upon orexin signaling and independent of norepinephrine and CRF in the BNST.