Implanted Microsensor Continuous IOP Telemetry Suggests Gaze and Eyelid Closure Effects on IOP—A Preliminary Study

PurposeTo explore the effect of gaze direction and eyelid closure on intraocular pressure (IOP).MethodsEleven patients with primary open-angle glaucoma previously implanted with a telemetric IOP sensor were instructed to view eight equally-spaced fixation targets each at three eccentricities (10°, 20°, and 25°). Nine patients also performed eyelid closure. IOP was recorded via an external antenna placed around the study eye. Differences of mean IOP between consecutive gaze positions were calculated. Furthermore, the effect of eyelid closure on gaze-dependent IOP was assessed.ResultsThe maximum IOP increase was observed at 25° superior gaze (mean ± SD: 4.4 ± 4.9 mm Hg) and maximum decrease at 25° inferonasal gaze (−1.6 ± 0.8 mm Hg). There was a significant interaction between gaze direction and eccentricity (P = 0.003). Post-hoc tests confirmed significant decreases inferonasally for all eccentricities (mean ± SEM: 10°: −0.7 ± 0.2, P = 0.007; 20°: −1.1 ± 0.2, P = 0.006; and 25°: −1.6 ± 0.2, P = 0.006). Eight of 11 eyes showed significant IOP differences between superior and inferonasal gaze at 25°. IOP decreased during eyelid closure, which was significantly lower than downgaze at 25° (mean ± SEM: −2.1 ± 0.3 mm Hg vs. −0.7 ± 0.2 mm Hg, P = 0.014).ConclusionsOur data suggest that IOP varies reproducibly with gaze direction, albeit with patient variability. IOP generally increased in upgaze but decreased in inferonasal gaze and on eyelid closure. Future studies should investigate the patient variability and IOP dynamics.     

Comparison of ambulatory and polysomnographic recording of jaw muscle activity during sleep in normal subjects

Clinicians and investigators need a simple and reliable recording device to diagnose or monitor sleep bruxism (SB). The aim of this study was to compare recordings made with an ambulatory electromyographic telemetry recorder (TEL-EMG) with those made with standard sleep laboratory polysomnography with synchronised audio-visual recording (PSG-AV). Eight volunteer subjects without current history of tooth grinding spent one night in a sleep laboratory. Simultaneous bilateral masseter EMG recordings were made with a TEL-EMG and standard PSG. All types of oromotor activity and rhythmic masseter muscle activity (RMMA), typical of SB, were independently scored by two individuals. Correlation and intra-class coefficient (ICC) were estimated for scores on each system. The TEL-EMG was highly sensitive to detect RMMA (0·988), but with low positive predictive value (0·231) because of a high rate of oromotor activity detection (e.g. swallowing and scratching). Almost 72% of false-positive oromotor activity scored with the TEL-EMG occurred during the transient wake period of sleep. A non-significant correlation between recording systems was found (r = 0·49). Because of the high frequency of wake periods during sleep, ICC was low (0·47), and the removal of the influence of wake periods improved the detection reliability of the TEL-EMG (ICC = 0·88). The TEL-EMG is sensitive to detect RMMA in normal subjects. However, it obtained a high rate of false-positive detections because of the presence of frequent oromotor activities and transient wake periods of sleep. New algorithms are needed to improve the validity of TEL-EMG recordings.     

Detection of QTc interval prolongation using jacket telemetry in conscious non-human primates: comparison with implanted telemetry

Background and Purpose: During repeat-dose toxicity studies, ECGs are collected from chemically or physically-restrained animals over a short timeframe. This is problematic due to cardiovascular changes caused by manual restraint stress and anesthesia, and limited ECG sampling. These factors confound data interpretation, but may be overcome by using a non-invasive jacket-based ECG collection (JET). The current study investigated whether a jacketed external telemetry system could detect changes in cardiac intervals and heart rate in non-human primates (NHPs), previously implanted with a PCT transmitter.Experimental Approach: Twelve male cynomolgus monkeys were treated weekly with vehicle or sotalol (8, 16, 32 mg kg⁻¹) p.o. ECGs were collected continuously for 24 hours, following treatment, over 4 weeks. A satellite group of six NHPs was used for sotalol toxicokinetics.Key Results: Sotalol attained C_max values 1–3 hours after dosing, and exhibited dose-proportional exposure. In jacketed NHPs, sotalol dose-dependently increased QT/QTc intervals, prolonged PR interval, and reduced heart rate. Significant QTc prolongation of 27, 54 and 76 msec was detected by JET after 8, 16, and 32 mg kg⁻¹ sotalol, respectively, compared with time-matched vehicle-treated animals. Overall, JET-derived PR, QT, QTc intervals, QRS duration, and heart rate correlated well with those derived from PCT.Conclusions and Implications: The current findings clearly support the use of JET to quantify cardiac interval and rhythm changes, capable of detecting QTc prolongation caused by sotalol. JET may be a preferred method compared to restraint-based ECG because high-density ECG sampling can be collected in unstressed conscious monkeys, over several weeks.     

Past,Present and Future of Home video-electroencephalographic telemetry: A review of the development of in-home video-electroencephalographic recordings

Video-electroencephalographic (EEG) monitoring is an essential tool in epileptology, conventionally carried out in a hospital epilepsy monitoring unit. Due to high costs and long waiting times for hospital admission, coupled with technological advances, several centers have developed and implemented video-EEG monitoring in the patient's home (home video-EEG telemetry [HVET]). Here, we review the history and current status of three general approaches to HVET: (1) supervised HVET, which entails setting up video-EEG in the patient's home with daily visiting technologist support; (2) mobile HVET (also termed ambulatory video-EEG), which entails attaching electrodes in a health care facility, supplying the patient and carers with the hardware and instructions, and then asking the patient and carer to set up recording at home without technologist support; and (3) cloud-based HVET, which adds to either of the previous models continuous streaming of video-EEG from the home to the health care provider, with the option to review data in near real time, troubleshoot hardware remotely, and interact remotely with the patient. Our experience shows that HVET can be highly cost-effective and is well received by patients. We note limitations related to long-term electrode attachment and correct camera placing while the patient is unsupervised at home, and concerns related to regulations regarding data privacy for cloud services. We believe that HVET opens significant new opportunities for research, especially in the field of understanding the many influences in seizure occurrence. We speculate that in the future HVET may merge into innovative new multisensor approaches to continuously monitoring people with epilepsy.     

双压力导管植入体比格犬体内植入手术的实施及在安全药理学研究中的应用

目的应用植入式遥测技术建立清醒比格犬动物模型,为药物临床前安全药理学评价研究提供理想的动物模型。方法选择6～8月龄、整体状况良好的比格犬,戊巴比妥钠（40 mg/kg,iv）麻醉后,通过外科手术,分别在胸腔、腹腔以及皮下植入呼吸压力导管、植入体主体和生物电（ECG）测定电极,股动脉插入血压测定压力导管,并进行细致周到的术后护理以防并发症的发生。植入手术成功后通过无线电遥测装置,经DSI清醒动物遥测系统自动记录、储存和分析动物在清醒状态下ECG、血压、呼吸和温度等生理参数。结果与结论成功地建立了植入式清醒比格犬动物模型,获得了稳定的ECG、呼吸、血压、体温等图形和数据。植入手术的操作及术后护理是建立植入式清醒比格犬动物模型成败的关键因素。     

Home blood pressure for the management of hypertension: will it become the new standard of practice?

Accurate identification of hypertension is crucial for the prevention of cardiovascular disease. Home blood pressure monitoring (HBPM) provides superior prediction of cardiovascular disease, compared with clinic pressures. HBPM can be a valuable resource for the effective treatment of hypertension, when combined with other modalities used to improve patient education, lifestyle enhancement, adherence to medication and reduction of unnecessary clinic visits. In some developed nations, more than half of households with a hypertensive patient have a device for HBPM. The use of HBPM by patients and the acceptance of HBPM measurements by providers is increasing. The long-term effectiveness of HBPM, combined with telemetry for disease prevention, is promising. More research is still needed to establish its full value. It is predicted that HBPM has definite potential for more effective strategies to control hypertension and reduce the need for on-site clinical care.     

Protective Effects of Valsartan and Benazeprilat in Salt-Loaded Stroke-Prone Spontaneously Hypertensive Rats

These experiments examined the effectiveness of chronic blockade of the renin angiotensin system with either valsartan or benazeprilat on survival, blood pressure and end-organ damage in salt-loaded stroke-prone SHR. Valsartan or benazeprilat given continuously by subcutaneous osmotic minipump beginning at 10.5 weeks of age lowered blood pressure, as determined by radiotelemetry, prevented proteinuria, prolonged survival and decreased the severity of histopathological changes in the heart and kidney. These results indicate that angiotensin receptor blockade affords a similar degree of protection as inhibition of angiotensin converting enzyme in salt-loaded stroke-prone SHR. Furthermore, our results are consistent with a primary contribution of angiotensin I1 to the maintenance of blood pressure and support a principal role for angiotensin II-dependent mechanisms in the development of end-organ damage in the salt-loaded strokeprone SHR.