两种剂量氟碳部分液体通气治疗犬吸入伤的比较研究

目的：对比研究两种剂量氟碳（PFC）部分液体通气（PLV）对蒸气吸入性损伤犬的血气和血流动力学的影响，方法：将健康犬15条随机分面两组，即PFC6ml/kg组（PFC－6）和PFC 12ml/kg(PFC-12)组，采用蒸气吸入造成吸入性损伤模型后经气管内注入PFC实施部分液体通气（PLV）治疗，观察治疗后30min,60min,90min血气，血流动力学参数的变化，结果：PFC－6组PaO2在PLV治疗30min后明显升高（P＜0．05），在治疗60min,90min生的PaO2与致伤值比较无统计学意义，而PFC－12组的PaO2在PLV治疗后30min,60min,90min均明显升高（P＜0．05），与PFC－6组相比，PFC－12组的PaO2,PvO2均呈上升趋势，但未达显著水平（P＞0．05），在PLV治疗后各时间点的PaCO2HR,MAP,CVP 致伤值相比均无明显变化（P＞0．05），两组之间比较，各对应时间点的PaCO2,HR,MAP,CVP也均无明显变化（P＞0．05），结论：氟碳部分液体通气是一种新的通气技术，它能明显改善蒸气入伤犬的氧合作用，对血液动力学参数无不良影响，两种剂量氟碳部分液体通气治疗蒸气吸入性损伤未呈现明显剂量一效应关系。     

无创正压通气不同压力支持水平对正常人呼吸做功的影响

目的 :观察无创正压通气 (NIPPV)不同压力水平对正常人呼吸做功的影响 ,为临床合理地应用NIPPV提供理论依据。方法 :选择 9例正常人行NIPPV并寻找出“最舒适”的吸气压力水平 (IPAP) ,在此压力基础上增加或减少 2 5 %的压力 ,构成低IPAP、最舒适IPAP和高IPAP三个压力水平 ,每一IPAP水平通气 15min以上 ,比较不同压力水平呼吸做功改变。结果 :受试者认为“最舒适”的IPAP为 (11.33± 3.2 0 )cmH2 O ,EPAP为 (4 .5 6± 0 .88)cmH2 O[相当于PSV水平为 (6 .77± 3.2 0 )cmH2 O]。与自主呼吸相比 ,NIPPV增加VE的同时 ,总的呼吸做功(Wtot)明显增加 (P <0 .0 5 ) ,而受试者吸气肌做功占总的吸气做功的百分比 (Wi,p/Wi)明显减少 (P <0 .0 5 )。在最舒适IPAP时 ,Wi,p/Wi降低到基础值的 14 %± 9%。这种变化趋势与IPAP的水平相关。结论 :NIPPV可以显著降低吸气肌肉做功。吸气肌做功减少的比例与IPAP的水平相关。研究的结果为NIPPV时PSV的参数设定提供了生理学的依据。     

The effects of inverse ratio ventilation on intracranial pressure: a preliminary report

Objective: To determine the effects of pressure control inverse ratio ventilation [PC-IRV], as compared with volume controlled normal ratio ventilation [VC], on the intracranial pressure [ICP] of patients with severe head injury. Design: A prospective study with unblinded intervention. Setting: The Intensive Therapy Unit of a base hospital. Patients and participants: Nine cases of head injury requiring mechanical ventilation and intracranial pressure monitoring were studied. Interventions: Patients were twice transferred from VC (I:E ratio 1:2) to PC-IRV (I:E ratio 2:1). Firstly, tidal volume was maintained at an equal value. Secondly, end tidal CO₂ was maintained at an equal value. No other changes were made to ventilation, vasopressor therapy or ICP control. Measurements and results: Measurements were taken of ICP, mean arterial pressure (MAP) end tidal CO₂ and respiratory parameters. In the first observation, there were significant changes in peak inspiratory pressure (PIP), mean airway pressure (Paw) and intrinsic positive end expiratory pressure (PEEP) but not for ICP, end tidal CO₂, MAP and cerebral perfusion pressure (CPP). The correlation between change in ICP and change in end tidal CO₂ was r=–0.74. In the second observation there were significant changes in tidal volume, PIP, Paw and intrinsic PEEP but not for ICP, MAP and CPP. The correlation between the change in ICP and the change in Paw was insignificant. Conclusions: PC-IRV has a minimal net effect on ICP. Changes in ICP correlate more strongly with changes in CO₂ than changes in Paw. Received: 16 January 1996 Accepted: 2 September 1996     

Nitric oxide administration after the ventilator: evaluation of mixing conditions

Background: Because of the potential toxicity of nitric oxide (NO) and its oxidising product nitrogen dioxide (NO₂), any system for the delivery of inhaled NO must aim at stable and predictable levels of NO and as low concentrations as possible of NO₂.
Methods: In a laboratory set-up, we have evaluated mixing conditions in a system where NO is added after the ventilator with continuous flow. Mixing was studied by using carbon dioxide (CO₂) as a tracer gas since capnography has a short response time (360 ms) in comparison with measurements of NO with electrochemical fuel cells (response time of 18s). CO₂ (in volumes corresponding to an ideal mixture of 1,3 and 6%) was fed, after the ventilator, either into plain breathing tubing, into one or two soda lime absorbers, or into an empty and a soda lime-filled canister, at different ventilatory rates and different I: E ratios. Samples were drawn from the inspiratory limb close to the Y-piece. NO was added in the same way and in the same volume as the highest concentration of CO₂.
Results: CO₂ added to plain tubing resulted in peak levels up to five times the set levels, while addition to a mixing box with an empty and a soda lime-filled canister resulted in even mixing with gas concentrations close to the ideal. When NO was fed into plain tubing, low levels were measured at the Y-piece, indicating poor mixing. Gas supply to a mixing chamber resulted in even concentrations.
Conclusions: Even and predictable levels of NO can be obtained with continuous flow of NO to the inspiratory limb, after the ventilator, if a mixing chamber is used. To obtain adequate mixing, the volume of the mixing box should be greater than the tidal volume.     

Radium-228 determination of natural waters via concentration on manganese dioxide and separation using Diphonix ion exchange resin

The objective of this work was to establish a new procedure for ²²⁸Ra determination of natural waters via preconcentration of radium on MnO₂ and separation of its daughter, ²²⁸Ac, using Diphonix ion exchange resin. Following removal of potential interferences via passage through an initial Diphonix Resin column, the first daughter of ²²⁸Ra, ²²⁸Ac, is isolated by chromatographic separation via a second Diphonix column. A holding time of >30 h for ²²⁸Ac ingrowth in between the two column separations ensures secular equilibrium. Barium-133 is used as a yield tracer. Actinium-228 is eluted from the second Diphonix Resin with 5 ml 1 M 1-Hydroxyethane-1,1-diphosphonic acid (HEDPA) and quantified by addition of scintillation cocktail and LSC counting. Radium (and ¹³³Ba) from the load and rinse solutions from the 2nd Diphonix column may be prepared for alpha spectrometry (for determination of ²²³Ra, ²²⁴Ra, and ²²⁶Ra) by BaSO₄ microprecipitation and filtration. Decontamination tests indicate that U, Th, and Ra series nuclides do not interfere with these measurements, although high contents of ⁹⁰Sr (⁹⁰Y) require additional treatment for accurate measurement of ²²⁸Ra. Addition of stable Sr as a “hold back” carrier during the initial MnO₂ preconcentration step was shown to remove most ⁹⁰Sr interference.     

压力调节容量控制通气对肺损伤犬血流动力学、呼吸力学和呼吸功能的影响

目的 探讨压力调节容量控制(PRVC)通气模式对健康及急性肺损伤(ALI)模型犬的血流动力学、呼吸力学和呼吸功能的影响。方法 PRVC和间歇正压通气(IPPV)两种通气模式在呼气末压为0、0．5、1．0和1．5kPa时，分别测定健康犬及油酸诱发ALI犬的血流动力学、呼吸力学及血气参数。结果 健康犬PRVC较IPPV模式下除了在PEEP为0．5kPa时，气道峰压(PIP)、肺动态顺应性(Cdyn)和肺血管阻力(PVR)的影响差异有显著性，对血流动力学、呼吸力学及呼吸功能的影响差异均无显著性。ALI犬PRVC较IPPV模式下各PEEP水平的PIP、平均气道压(mPaw)、Cdyn、动脉血氧分压[pa(O2)]和氧耗(VO2)的影响均有显著意义，但两种通气模式对血流动力学的影响差异无显著性。结论 与IPPV相比，PRVC通气模式能降低PIP，增加Cdyn和提高pa(O2)，两模式对血流动力学的影响差异无显著性，PRVC更适用于ALI／ARDS的治疗。     

心理支持疗法对机械通气患者应激反应的影响

目的 观察心理支持疗法(PST)对ICU患者机械通气应激反应的影响。方法 将34例连续机械通气时间在20h的清醒患者，随机分为采用标准的PST方法进行治疗的观察组和对照组，观察焦虑抑郁程度和应激反应改变情况。结果 对照组患者的焦虑抑郁程度明显高于观察组，部分应激反应激素水平升高幅度也明显大于观察组。结论 PST可通过缓解机械通气患者的焦虑抑郁等不良情绪状态减轻机械通气带来的各种心身应激反应，有利于提高机械通气治疗的有效性和安全性。     

Double layer capacitance and a microscopic structure of electrified liquid–liquid interfaces

We develop a theory of the double layer at electrolyte–electrolyte interfaces taking in to account the microscopic structure of the interfacial region. This includes a “mixed boundary layer” where the overlapping of two space-charge regions occurs, and the effects of ion association and adsorption at the interface. Theoretical results are in good agreement with experimental data obtained for various organic solvents and electrolytes. The theory suggests a framework for the treatment of the capacitance data and establishes a relationship between experimental results and the microscopic structure of interfaces between two immiscible electrolyte solutions (ITIES).     

舒利迭加无创通气治疗稳定期慢性阻塞性肺疾病的临床研究

目的探讨舒利迭(吸入型肾上腺皮质激素与长效β2-受体激动剂的预混制剂)联合双水平气道正压通气(B iPAP)对稳定期慢性阻塞性肺疾病(COPD)的治疗作用。方法稳定期COPD病人52例,舒利迭TM50/250,1吸/次,2次/d;B iPAP,吸气压力(IPAP)10~20cm H2O,呼气压力(EPAP,也称PEEP)3~6cm H2O,吸氧浓度(FiO2)3L/m in,每天夜间通气6~8h。观察治疗前、治疗后12周病人临床症状、生活质量、健康状态和肺功能。结果治疗前、治疗后12周病人的临床症状、急性加重次数及严重程度、健康状态和生活质量、肺功能等指标比较差异有统计学意义(P<0.05)。结论舒利迭联合B iPAP治疗稳定期COPD病人能够明显改善其症状,提高生活质量,有一定的临床应用价值,对减缓COPD病人肺功能下降有积极意义。