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.     

动物细胞培养过程中pH和溶氧的关联控制

本文通过对动物细胞培养过程中pH值和溶氧(DO)水平控制要求的分析,设计了用空气、氧气、氮气和二氮化碳四组气体关联控制pH值和DO水平的控制系统。该系统根据对瞬时pH值和DO值参数的检测,通过微处理机进行一系列的逻辑判断和具有PI调节规律的DDC增量词节计算,再经四气体关联互补计算和多重时序控制环节,综合调节四组气体电磁阀的相互开闭时间,实现对培养过程中pH值和DO水平的控制,满足动物细胞生长的需要。     

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。     

橡胶木粉填充LLDPE复合材料的结构和力学性能

用橡胶木粉填充线性低密度聚乙烯(LLDPE)，研究了酸、碱溶液预处理木粉的效果和硅烷偶联荆(KH-570)、MMA接枝的天然橡胶胶乳(MGL-30)两种改性剂对橡胶木粉表面改性的效果，以及未粉粒径和填充量等对木粉／LLDPE复合材料力学性能的影响，并用SEM对复合材料拉伸断面的形态结构进行了分析。结果表明：木粉的拉径、木粉填充量和改性荆用量对复合材料的力学性能有较大的影响，经碱溶液预处理再用改性荆改性后的木粉能有效地改善木粉与LLDPE的界面粘结强度，提高橡胶木粉／LLDPE复合材料的力学性能。     

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。     

山莨菪碱和无创面罩正压通气治疗急性呼吸窘迫综合征的临床观察

目的比较山莨菪碱联合无创正压面罩通气（654-2＋NIPPV）和传统机械通气（CMV）治疗急性呼吸窘迫综合征（ARDS）的临床效果，评估山莨菪碱联合无创正压通气在ARDS治疗中的作用。方法将各种原因所致ARDS患者42例随机分为654-2＋NIPPV组（21例）和CMV组（21例），在给予病因治疗同时分别实施654-2＋NIPPV和CMV。观察分析两组患者在治疗过程中动脉血气变化、并发症的发生率及治疗效果。结果654-2＋NIPPV组有8例（38．1％）治疗失败转为气管插管实行CMV，其中6例（28．6％）死亡。CMV组死亡7例（33．3％），两组病死率无显著差异（P〉0.05）。两组治疗有效的患者在分别接受654-2＋NIPPV和CMV治疗后1h和6h动脉血气有相似的显著改善。654-2＋NIPPV组患者机械通气时间和住院时间短于CMV组（P〈0.05）。654-2＋NIPPV组的并发症发生率低于CMV组（P〈0.05）。结论在经过选择的ARDS患者中，应用654-2＋NIPPV治疗的临床效果与CMV相似。实施654-2＋NIPPV可缩短机械通气和住院时间，减少并发症。654-2＋NIPPV可作为经过选择的ARDS患者首选的通气支持治疗手段。