Non-contact tonometry synchronized with cardiac rhythm and its relationship with blood pressure

PURPOSE: The main objectives of this study were to determine the differences between non-synchronized intraocular pressure (IOP_N) and intraocular pressure readings synchronized with cardiac pulse and try to determine if these parameters are related to blood pressure values. METHODS: One hundred and sixty-five right eyes from 165 volunteers (107 females, 58 males) aged from 19 to 73 years (mean +/- S.D., 29.93 +/- 11.17) were examined with the Nidek NT-4000, a new non-contact tonometer that allows the measurement of IOP synchronized with the cardiac rhythm. IOP measurements in the four different modes of synchronization were taken in a randomized order. Three measures of each parameter were taken and then averaged. The blood pressure was determined three times with a portable manometer and mean values of systolic and diastolic pressure and the pulse rate were computed. Mean arterial pressure (MAP) was determined as being 1/3 of systolic plus 2/3 of diastolic blood pressure. RESULTS: The mean +/- S.D. values for the standard intraocular pressure (IOP_N: 14.76 +/- 2.86), intraocular pressure in the systolic instant or peak (IOP_P: 14.99 +/- 2.85), intraocular pressure in the middle instant between heartbeats or middle (IOP_M: 14.68 +/- 2.76), and intraocular pressure in the diastolic instant or bottom (IOP_B: 13.86 +/- 2.61) were obtained. The IOP_P was higher than the remaining values. A significant difference in mean IOP existed between IOP_B and the remaining modes of measuring (p < 0.05). Differences were statistically significant for all pair comparisons involving IOP_B. Arterial blood pressure values were systolic 125.5 +/- 14.22, diastolic 77.7 +/- 8.38 and MAP 93.64 +/- 9.44 mmHg. The pulse rate was 77.3 +/- 12.6 beats per minute. Except for the MAP (p = 0.025) there was no significant correlation between different IOP values and systolic or diastolic blood pressure, or pulse rate. CONCLUSIONS: NT-4000 is able to differentiate IOP values when synchronized with the cardiac rhythm and those differences are expected to be within a range of +/-2.5 to +/- 3.0 mmHg. IOP_B seems to be the parameter whose value differs from the non-synchronized and the remaining synchronized parameters in a significant way. Other than a weak association with MAP, no significant correlation between IOP and BP was found. The measurements of IOP readings for the three modes are consistent with timings during the cardiac cycle and IOP pulse cycle.     

Clinical performance of non-contact tonometry by Reichert AT550® in glaucomatous patients

Measuring intraocular pressure (IOP) by non-contact tonometry (NCT) has been demonstrated to be a valid and reliable technique to be used in primary eye care; it is easier to use, it does not transmit infectious diseases, and it is not necessary to use anaesthetic or staining eye drops. Recently, a new NCT device has showed an excellent level of agreement with Goldmann tonometry, but there are no records of its performance in glaucomatous eyes. To rectify this, IOP was measured in twenty-two patients (44 eyes) receiving medical treatment to control elevated IOP, with AT550 and Goldmann tonometry. Mean values of IOP were 18.98 +/- 2.77 and 19.08 +/- 3.02 mmHg using Goldmann and AT550, respectively. Plots of differences against means displayed good agreement (mean difference +/- limits of agreement, -0.09 +/- 3.30); this value was not significantly different from zero (t-test for dependent samples, p = 0.709). In conclusion, IOP values as measured with the AT550 NCT are clinically comparable with those obtained with Goldmann tonometry in glaucomatous patients. This validates this NCT not only for screening of IOP but to follow-up glaucomatous patients with a rapid, non-invasive method.     

医用磁感应阻抗成像敏感性基础研究

在设计并实现了1个16通道的磁感应阻抗成像系统的基础上，为了研究成像算法，考察了测量信号的幅度和相位与被测物的位置之间的关系。基于成像系统，采用高精度鉴幅和鉴相的方法进行信息提取。得到了感应信号的幅度与相位沿水平和竖直方向的变化规律，绘制了敏感性变化曲线。结果表明：测量位置不同，检测到的感应信号有很大变化，变化趋势是有规律的，对这种规律的研究有利于更好地重建图像。     

Ultrathin films of charged polysaccharides assembled alternately with linear polyions

As a means of preparation of biocompatible molecular surfaces, an alternate assembly of charged polysaccharides and oppositely-charged synthetic polymers was conducted. Cationic chitosan was assembled alternately with anionic poly(sodium styrenesulfonate) (PSS) at pH 4. Regular film growth and its dependence on ionic strength were detected by the quartz crystal microbalance (QCM) method. Averaged film thicknesses for the chitosanCPSS layer were 15, 31, 46, and 69 A° , respectively, when 0, 0.25, 0.5, and 1 M of NaCl was contained in aqueous chitosan. Adsorption of chitosan did not reach saturation in 20 min at 0 M NaCl, while the adsorption became saturated within 6 min with 0.25 M NaCl. Anionic sodium chondroitin sulfate was also assembled in alternation with cationic poly(dimethyldiallylammonium chloride) (PDDA) at pH 6.5. The adsorption of chondroitin sulfate was less sensitive to ionic strength. Surface morphology of chitosan–PSS films was investigated by non-contact atomic force microscopy (AFM) observation. Maximum height difference and Ra value for a 1000 × 1000 nm area were 11 and 0.69 nm, respectively, indicating the formation of a molecularly flat surface by alternate layer-by-layer adsorption.     

无接触无菌技术在妇科病人PICC维护中的应用效果观察

目的:探讨无接触无菌技术在经外周静脉置入中心静脉导管(PICC)日常维护中应用的临床效果。方法:按住院号的单双号把80例病人分成对照组及试验组,对照组使用PICC专门换药包进行PICC导管维护,试验组不使用换药包但执行无接触无菌技术。结果:两组病人在导管维护耗时、使用物料成本方面比较差异有统计学意义(P<0.05),试验组优于对照组,在并发症发生、病人满意度比较方面差异无统计学意义(P>0.05)。结论:无接触无菌技术用于PICC导管日常维护可以节省护士工作时间及物料消耗。     

非接触式医疗监测雷达研究进展

介绍了非接触式医疗监测雷达相比于传统的呼吸和心电监护仪的优势,从3种不同雷达体制的角度总结回顾了近10 a来医用生命监测雷达系统的研究现状,概括比较了呼吸和心跳信号的提取、分离、杂波抑制等算法,并指出了各种算法的优缺点,最后对非接触式生命监测雷达的发展趋势进行了探讨和展望.     

A novel method to estimate changes in stress-induced salivary α-amylase using heart rate variability and respiratory rate,as measured in a non-contact manner using a single radar attached to the back of a chair

The authors have developed a non-contact system which estimates changes in salivary α-amylase (sAA ratio) induced by stress. Before and after stressful sound exposure, a single 24?GHz compact radar which is attached to the back of a chair measures the low frequency (LF) component of heart rate variability and respiratory rate, α-amylase in the subjects’ buccal secretions was measured by using an α-amylase assay kit. Using multiple regression analysis, sAA ratio was estimated using stress-induced LF change (LF ratio) and stress-induced respiratory rate change (respiratory rate ratio). Twelve healthy subjects were tested (12 males, 22?±?2 years), who were exposed to audio stimuli with a composite tone of 2120?Hz and 2130?Hz sine waves at a sound pressure level of 95?dB after a silent period through a headphone. The result showed that sAA ratio estimated using multiple regression analysis significantly correlated with measured sAA ratio (R?=?0.76, p?相似文献   

动态轮廓眼压计监测LASIK手术前后眼压变化

目的比较动态轮廓眼压计(DCT)、Goldmann压平式眼压计(GAT)及非接触式眼压计(NCT)测量接受准分子激光原位角膜磨镶术(LASIK)患者眼压值的差异。设计前瞻性临床试验研究。研究对象接受LASIK治疗的近视患者70例(140眼)。方法对上述患者于术前、术后1周,1、6个月用三种不同眼压计分别测量眼压,比较各时间点、各种眼压计之间的差异。同时记录手术前、后中央角膜厚度,取其两者差为角膜切削深度的值。主要指标眼压值(IOP)和角膜切削深度。结果术后1周,1、6个月DCT测量值(16.74±1.96mmHg、16.67±1.90mmHg、16.42±2.12mmHg)与其术前值(17.36±2.32mmHg)比较差异无统计学意义(F=1.346,P=0.06)。术后GAT和NCT测量值均呈下降趋势,与术前测量值比较差异有统计学意义(GAT:F=101.217,P=0.000;NCT:F=171.466,P=0.000),并且下降值与角膜切削深度成正相关关系(GAT:r=0.86,P=0.000;NCT:r=0.87,P=0.000),但术后三个时间段测量值比较差异无统计学意义(GAT术后三个时间点q值为0.216、0.677、0.461,P值分别为0.461、0.097、0.117;NCT术后三个时间点q值为0.215、0.585、0.370,P值分别为0.436、0.436、0.100)。结论LASIK术后GAT和NCT测量值明显下降,而DCT测量值无显著变化,其测量值较前两者更为可靠。(眼科,2007,16:344-347)     

美多丽-P诊断性散瞳前后眼压差异的研究

目的:观察用美多丽-P诊断性散瞳后眼压的变化情况。方法:选取2006-12/2007-02间在本院眼科门诊就诊患者56例(87眼),进行诊断性散瞳,散瞳前后用非接触式眼压计(NCT,Topcon CT-80A)分别进行眼压测量,比较散瞳前后眼压的差异。结果:活动性散瞳后双眼眼压均比散瞳前升高,两者差值分别为:右眼2.00±1.70mmHg,左眼1.77±1.94mmHg(P<0.001)差异具有统计学意义。对于同时进行双眼活动性散瞳的31例患者的左右眼间差异进行比较,差值为0.39±1.28mmHg,P>0.05无统计学意义。相同眼别,活动性散瞳前后进行相关性比较,右眼r=0.853,左眼r=0.806,P<0.01,具有统计学意义。结论:散瞳后可引起眼压的升高,甚至有诱发急性青光眼的可能,因此诊断性散瞳前对基础眼压的测量尤为重要,有利于保证医疗护理工作的安全。