Carbon dioxide recruitment threshold as a predictor of successful weaning in chronic obstructive pulmonary disease patients: A pilot study

Abstract Several methods have been used to predict successful weaning and extubation among chronic obstructive pulmonary disease (COPD) patients. The objective of this study is to determine whether carbon dioxide recruitment threshold (PCO₂RT) can be used as adjunct to conventional weaning parameters to predict early weaning and successful extubation. Twelve COPD patients who were ready to be extubated based on conventional weaning parameters were divided into group A ( n = 7) and group B ( n = 5). Group A were those patients with better weaning parameters and hence a higher probability of successful extubation as compared to group B. Carbon dioxide apnoeic threshold (PCO₂AT) was obtained by hyperventilating the patient using an increment of two breaths per min until apnoea occurs. At this point, the PCO₂AT or the PaCO₂ during said apnoeic period was recorded. A dead space of 150 cc is then added to the circuit until the patient starts to breathe as evidenced by the sensitivity trigger indicator. The PCO₂ obtained at this period is termed PCO₂RT. After weaning for 30 min on a T-tube, another arterial blood gas is determined and this is called the PCO₂SB or the CO₂ level after 30 min on spontaneous breathing. If the PCO₂SB-PCO₂RT difference is high with a sensitivity of 85.71% and specificity of 100% vs sensitivity of 57.14% and specificity of 60% using the conventional weaning parameters. Thus an increase in PCO₂SB at 30 min T-tube is indicative of impending respiratory pump failure and that other causes of failure to wean must be investigated.     

慢性阻塞性肺疾病前驱性呼吸衰竭患者呼吸驱动的改变

目的探讨慢性阻塞性肺疾病(COPD)和COPD前驱性呼吸衰竭(前驱呼衰)患者中枢呼吸驱动的改变;评价界定COPD前驱性呼吸衰竭的临床意义.方法试验对象为COPD前驱性呼吸衰竭、COPD尚未达前驱性呼吸衰竭的患者和健康对照者各30名.所有受试者均进行如下参数的测定:动脉血气分析;常规肺功能,主要以第1秒用力呼气容积(FEV1)占预计值的百分比(FEV1%)来评价;中枢呼吸驱动水平,以0.1 s口腔阻断压(P0.1)、校正中枢呼吸驱动(以每分通气量来校正,即P0.1/MV)和吸气阻抗P0.1/VT/Ti)等来评价.结果P0.1和P0.1/MV在COPD前驱呼衰组明显高于正常对照组和未达前驱呼衰组,P0.1/VT/Ti在COPD前驱呼衰组和未达前驱呼衰组明显高于正常对照组(P=0.002);P0.1,P0.1/MV,P0.1/VT/Ti与PaO2,FEV1%呈显著负相关(rs=-0.769,-0.495,-0.543;-0.747,-0.480,-0.526,P均＜0.01);与PaCO2呈显著正相关(rs=0.270,0.312,0.369,P分别为＜0.05,＜0.01,＜0.01).结论COPD前驱呼衰患者呼吸储备能力减低,呼吸效率下降;P0.1,P0.1/MV,P0.1/VT/Ti等参数在推断患者神经-肌力输出水平与呼吸衰竭发生阈值方面具有较大的意义.当COPD进展至前驱呼衰阶段,从血气分析、肺功能检查到呼吸驱动水平都发生了显著的改变,从而提示界定此阶段具有一定的临床意义.     

超声引导下经皮经肝胆管穿刺置管引流在梗阻性黄疸病人中的应用

目的　评价超声引导下经皮经肝穿刺胆管置管引流 (UPTBD)对梗阻性黄疸病人的治疗价值。方法　对 1995年 1月至 2 0 0 2年 7月期间的 4 17例梗阻性黄疸病人进行 4 97次UPTBD治疗 ,并回顾总结他们的临床资料。结果　接受PTBD治疗共有 4 17例 (5 1例病人进行了两个胆管枝的PTBD) ,穿刺成功率达 93.2 % (4 36 / 4 6 8) ,32例首次穿刺失败的病人有 2 9例进行了第二次穿刺置管 ,全部成功。发生胆汁漏 /胆汁性腹膜炎 9例 ,胆道出血 8例 ,感染性休克 1例 ,无腹腔出血、后腹膜血肿、气胸等其他并发症。对 6 4例置管引流患者进行肝功能检测 ,与穿刺前相比 ,引流后 1周和 3周检测病人血清胆红素、转氨酶均显著下降。结论　UPTBD是一项姑息性治疗梗阻性黄疸的快捷、安全、有效的方法     

低压状态下猪鼾症模型的建立及其CT研究

目的探讨低压环境对动物上气道软组织形态学的影响。方法将试验猪置于一个低压环境饲养6个月建立猪的鼾症模型,当出现类似鼾症临床症状和鼾症相似的咽腔压力波形时,再进行CT扫描影像学检查。并与正常状态饲养的对照组进行对比。结果模型猪咽后壁及软腭明显增厚,分别为(0.94±0.16)cm和(1.06±0.23)cm;对照组分别为(0.60±0.11)cm和(0.59±0.13)cm。模型猪的气管截面积在在前、中、后部分别为(1.49±0.12)cm2、(1.37±0.32)cm2和(1.00±0.21)cm2,其中以悬雍垂水平(后部)最为狭窄;对照组前、中、后部分别为(1.30±0.14)cm2、(1.57±0.32)cm2和(2.48±0.42)cm2。结论低压状态是鼾症的重要的致病因素之一,低压状态可建立鼾症的动物模型。     

慢性阻塞性肺疾病患者家庭支持与自我概念的相关性研究

目的 探讨慢性阻塞性肺疾病(慢阻肺)患者的家庭支持与自我概念的关系。方法 用方便抽样法选取108位慢阻肺患者，应用修订的个人资源问卷、自我概念量表和一般资料问卷分别测定其家庭支持、自我概念水平和一般资料。结果 该组患者家庭支持程度为中到高度，自我概念中度积极；家庭支持与总的自我概念呈中度正相关，与自我概念中的体感、自我一致性、理想自我及道德一伦理一精神自我有显著相关．与体象无关。结论 慢阻肺患者的家庭支持水平越高，其自我概念越积极。     

梗阻性黄疸患者的内毒素血症及其对机体的影响

４９例梗阻性黄疸患者（实验组）和８１例无黄疸的胆系疾病患者（对照组）围手术期外周血的内毒素（ＥＴ）检测结果表明，实验组：①术前ＥＴ阳性率明显高于对照组（Ｐ＜０．００１）；②术后１０～１２ｄ夹闭Ｔ／Ｙ管后ＥＴ阳性率明显低于术前和夹管前（Ｐ＜０．００１）；③伴急性化脓性胆管炎（ＡＣＳＴ）的患者ＥＴ阳性率明显高于无ＡＣＳＴ的患者（Ｐ＜０．００１）；术前口服胆盐的患者ＥＴ阳性率则显著低于未口服胆盐者（Ｐ＜０．００１）．作者认为，本组梗阻性黄疸患者中出现的肾功能障碍、胃肠道出血以及２例患者的死亡，至少部分地与内毒素血症有关。     

阻塞性睡眠呼吸暂停综合征患者手术治疗的麻醉研究

目的：探讨阻塞性睡眠呼吸暂停综合征(obstructive sleep apnea syndrome，OSAS)患者手术治疗的麻醉处理。方法：72例OSAS患者手术前先正压通气治疗(continue positive airway pressure，CPAP)和评价上气道，55例患者经鼻或经口气管插管全身麻醉；在手术完毕患者完全清醒后拔除插管。结果：72例患者中，轻度16例、中度24例、重度32例。合并晨起高血压28例，心电图均有不同程度心肌缺血的表现；红细胞增多症12例；腭咽平面Ⅰ级9例、Ⅱ级24例、Ⅲ级的27例、Ⅳ级12例。术前3．5d行自动调压正压通气治疗(Auto—CPAP)，经口气管内插管48例，经鼻气管内插管6例，均无术中插管困难和术后高血压危象，呼吸道梗阻发生。结论：充分认识OSAHS患者全身麻醉的手术风险，术前CPAP治疗和上气道评估，术中正确处理、严格掌握气管内插管、术后拔管的时机，是保证OSAHS患者手术成功、麻醉安全的关键。     

舒胆合剂防治阻塞性黄疸肾功能障碍的作用机制

目的 探讨在阻塞性黄疸(OJ)时舒胆合剂的抗内毒素及对肾功能的保护作用。方法 SD大鼠胆总管结扎后分3组，每组10只，分别用2mL舒胆合剂、乳果糖液(每100mL含乳果糖67g)、生理盐水灌胃，连用9d。假手术组10只，用2mL生理盐水灌胃。观察内毒素、血和肾组织中内皮素(ET)、一氧化氮(NO)的含量、一氧化氮合酶(NOS)活性及肾功能的变化。结果 舒胆合剂组与乳果糖组血内毒素、血和肾组织ET水平较生理盐水组明显降低，血和肾组织N0、NOS活性、内生肌酐清除率、肾皮质血流量较生理盐水组明显升高。结论 在OJ时，中药舒胆合剂有抗内毒素作用，并通过减少体内内毒素水平来降低体内ET水平，升高N0水平起到保护肾功能的作用。     

阻塞性睡眠呼吸暂停患者临床表现与上气道阻塞部位关系的探讨

目的 观察一组AHI接近的阻塞性睡眠呼吸暂停综合征（OSAS）患者中上气道阻塞部位对多导睡眠监测（PSG）图及临床表现的影响。方法选取36例AHI为30—40的成年男性OSAS患者行再次整夜PSG，加同步上气道及食道压力监测确定上气道最低阻塞部位。比较上气道最低阻塞部位在软腭水平、舌根水平和下咽水平的不同患者中PSG相关参数：平均SaO2、最低SaO2、最长阻塞性呼吸暂停事件时间、呼吸暂停事件中SaO2下降率（dSaO2／dt）、微觉醒指数；以及部分临床表现参数：白日嗜睡程度、入睡前收缩压／清晨收缩压、入睡前舒张压／清晨舒张压以及高血压发生率。结果平均SaO2、最长阻塞性呼吸暂停事件时间和入睡前收缩压／清晨收缩压比值在3种不同上气道最低阻塞部位患者中差异无显著性（P〉0．05），但与软腭水平相比，舌根水平和下咽水平的最低Sa02降低（P〉0．05），dSaO2／dt（％／s）比值增高（P〈0．05），微觉醒指数及白日嗜睡评分增高（P〈0．01），入睡前舒张压／清晨舒张压比值降低（P〈0．05），最低SaO2〈80％的发生率增高（P〈0．01）以及高血压的发生率增高（P〈0．01）。结论AHI接近的OSAS患者上气道阻塞部位在舌根水平以下者与软腭以上水平者相比，阻塞性呼吸暂停事件的致缺氧效率和程度提高，OSAS的临床表现加重。     

Pressure stability of nasal CPAP and bilevel devices

Summary Question of the study   Nasal continuous positive airway pressure (CPAP) prevents collapse of the upper airway during sleep in patients with obstructive sleep apnea provided that a positive transmural pressure can be maintained during inspiration. We examined pressure-flow characteristics in seven CPAP and bilevel devices during spontaneous breathing.
Methods   The CPAP devices were set to a pressure level of 9.8  hPa (10  cm H₂O) and adapted to a pneumotachograph using a standard CPAP hose and an outlet valve. We continuously measured flow, volume and pressure during resting ventilation and increasing voluntary hyperventilation and analysed the dependence of the variables on a breath-to-breath basis.
Results   Mean CPAP pressures differed between the devices (9.9 – 10.6  hPa) despite the same settings. In all machines pressure fell during inspiration to 8.4 – 9.8  hPa and increased during expiration to 11.1 – 11.7  hPa. This effect increased with higher flow rates. Maximum expiratory pressures rose to 12 – 19  hPa at peak flow rates of 2 l/s, mean expiratory pressures to 9.5 – 16  hPa. Inspiratory pressures dropped to 8.5 – 4.5  hPa (minimum) and 10.5 – 6.0 (mean). Bilevel devices showed a higher stability than CPAP devices. Pressure swings during the respiratory cycle increased the additional work of breathing.
Conclusions   Due to differences in mean and effective CPAP levels CPAP devices are not simply exchangeable but should be individually adapted. Patients with higher minute ventilation might benefit from more stable CPAP machines. The impact on patients' compliance remains to be evaluated.