基于Matlab无创正压通气下呼吸道气阻与顺应性的在线测算方法研究

目的 在无创正压通气下,避免对呼吸道内部进行操作以及自主呼吸和漏气的干扰等,研究有效在线动态测算呼吸道气阻（resistance, R）和顺应性（compliance, C）的方法。方法 在呼气末气流为0时,控制呼气支持压（expiration positive airway pressure,EPAP）跃降1个幅度为Δp和时间宽度为Δt的负脉冲气压;在该负脉冲气压作用下,呼吸道出现短暂释放气流;通过获得Δt时间段的释放气流计算R和C。另外,基于Matlab建立通气模型,模拟正常成人、急性呼吸窘迫综合征（acute respiratory distress syndrome, ARDS)患者和慢性阻塞性肺疾病（chronic obstructive pulmonary disease, COPD）患者的呼吸,进行仿真实验,获取仿真数据并计算验证。结果 根据仿真数据计算得到正常成人、ARDS患者、COPD患者R和C与实践赋值的误差分别为1.6%和-1.6%、1.21%和-1.19%、-12.53%和14.32%。结论 该算法测算呼吸道R和C具有可行性和适应性。仿真研究结果有助于智能通气、比例辅助通气模式的研究与实现。     

无创正压通气与呼吸兴奋剂辅助治疗慢阻肺急性呼吸衰竭的比较研究

目的 比较无创正压通气(NIPPV)和呼吸兴奋剂辅助在治疗慢阻肺急性呼吸衰竭的效果.方法 对50例COPD患者分为两组,一组给予双水平气道内正压通气(NIPPV),另外一组给予呼吸兴奋剂辅助治疗.结果 NIPPV可以显著的降低患者的血压、心律和呼吸频率,是治疗COPD的有效方法.结论 NIPPV在治疗COPD优于呼吸兴奋剂辅助.     

阻塞性睡眠呼吸暂停中呼气阶段的作用

阻塞性睡眠呼吸暂停 (OSA)中呼气阶段的作用不是很清楚。此研究的目的是通过评估持续气道内正压通气(CPAP)、间歇正压通气 (IPPV )和双相气道内正压通气(BIPAP)的短期治疗效果来证明在 OSA患者中呼气狭窄对呼气暂停的作用。研究对象选择一年来就诊的 80例 OSA患者中挑选的10例 OSA患者 ,均基于至少 10 cm H2 O的 CPAP治疗压水平。选择标准是至少占 85 %阻塞的严重 OSA,无反发性中枢神经系统功能紊乱史或临床表现 ,原发性心脏病或神经肌肉病 ;无右心衰竭或呼吸衰竭的表现 ;无肺部疾患 ;以前无换气治疗 ,无药物治疗史。持续气道…     

无创双水平气道正压通气在急性呼吸窘迫综合征患者中的应用效果分析

目的 对急性呼吸窘迫综合征（ARDS）患者采取无创双水平气道正压通气治疗的应用效果进行分析。方法 选取2017年2月~2018年1月我院收治的50例ARDS患者,随机分为对照组和研究组,每组25例。对照组采取鼻塞式持续气道正压通气治疗（NCPAP）,研究组采取双水平气道正压通气治疗（BiPAP）,对比两组治疗前、治疗48 h的PaO2、PaCO2、SpO2指标、氧疗时间以及治疗成功率。结果 研究组患者经治疗48 h的PaO2、PaCO2、SpO2指标均优于对照组,差异具有统计学意义（P＜0.05）;研究组氧疗时间少于对照组[（70.35±14.33）h vs （88.79±12.63）h],治疗成功率高于对照组（96.00% vs 80.00%）,差异具有统计学意义（P＜0.05）。结论 采取无创双水平气道正压通气治疗ARDS患者,可显著改善患者的气血分压指标,缩短氧疗时间,提高治疗成功率。     

慢性阻塞性肺疾病机械通气呼吸力学容积依赖性系数与内源性呼气末正压的相关性分析

目的 探讨慢性阻塞性肺疾病(COPD)患者机械通气时呼吸力学非线性分析时呼吸系统弹性和阻力的容积依赖性系数(Evd/Rvd)与内源性呼气末正压(PEEPi)的相关性.方法 2004年1月-2005年1月本院英东重症监护医学中心收治的25例COPD机械通气患者,分别以呼吸力学的线性和非线性模型分析其压力(P)、流量(V')和容量(V)数据,比较二者的拟合效率指标决定系数(R2)和根均方差(RMSD);以呼气末阻断法测定PEEPi,分析弹性容积依赖性系数(Evd)、阻力容积依赖性系数(Rvd)以及Evd×Rvd与PEEPi的相关性.结果 非线性分析所得的RMSD值(1.47±0.81)cm H2O小于线性分析所得(2.36±1.18)cm H2O;非线性分析所得的R2值(0.97±0.02)大于线性分析(0.89±0.08),差异均有统计学意义(P均＜0.05);Evd、Rvd以及Evd×Rvd与PEEPi的相关系数分别为0.90、0.82和0.95(P均＜0.01).结论 呼吸力学的非线性模型比线性模型更加适合COPD患者机械通气时呼吸力学分析.Evd和Rvd,特别是Evd×Rvd与PEEPi之间具有良好的相关性,或可用于COPD患者机械通气时PEEPi的无创性持续监测.     

肺复张对ARDS患者呼吸力学的影响

目的 观察呼气未正压(PEEP)递增法肺复张联合保护性通气对急性呼吸窘迫综合征(ARDS)肺换气功能及血流动学的影响.方法 对35例ARDS患者行PEEP递增法肺复张;测定肺复张前及肺复张后10mim、30min、1h、4h、24h时患者的氧合、呼吸力学和循环指标变化.结果 肺复张后的脉搏血氧饱和度(SpO2)、动脉血氧饱和度(SaO2)、动脉血氧分压(PaO2)、氧合指数(PaO2/FiO2 )呈进行性升高,气道平台压 (Pplat)呈进行性降低,与肺复张前比较,差异有统计学意义( P<0.01或 P<0.05).实施肺复张前后二氧化碳分压(PaCO2)、PH值、气道峰压(PIP)、心率(HR)、平均动脉压(MAP)、中心静脉压(CVP)均无明显变化,差异无统计学意义(P>0.05).结论 PEEP递增法肺复张结合肺保护通气策略是治疗ARDS的安全有效措施.     

气道内高压力促进3种气道重塑相关因子的表达

目的探讨机械通气情况下气道内不同压力水平对气道重塑相关因子表达的影响。方法手术室经全麻行机械通气的42例慢性阻塞性肺疾病(COPD)作为COPD组和33例无基础肺疾病患者作为对照组。机械通气根据吸气峰压(PIP)水平又分为高、中、低压力组(分别为24、22和20 cm H_2O),呼气末正压均为5 cm H_2O。机械通气前及3 h后收集支气管肺泡灌洗液(BALF)。酶联免疫吸附法和Western blot法检测BALF中气道重塑相关因子成纤维生长因子2(FGF-2)、转化生长因子-β1(TGF-β1)和基质金属蛋白酶-9(MMP-9)蛋白表达水平。结果 1)机械通气前COPD组BALF中的FGF-2、TGF-β1和MMP-9蛋白水平明显高于对照组(P0.01)。2)机械通气后对照组在高压力刺激下FGF-2、TGF-β1和MMP-9表达水平升高(P0.05);而COPD组压力刺激下上述3种蛋白表达升高更明显(P0.05),且高压力组中及低压力组(P0.05)。3)相关性分析显示,COPD组BALF中FGF-2、TGF-β1、MMP-9表达水平与气道压力成正相关(P0.01)。结论机械通气时气道内的持续高压力可能通过作用于气道上皮细胞内压力敏感通道进而提高气道重塑因子FGF-2、TGF-β1、MMP-9的表达水平,COPD患者尤为显著。     

60例慢性阻塞性肺疾病患者无创正压通气治疗中不良反应及护理

慢性阻塞性肺疾病（COPD)是一种具有气流受限特征可以预防和治疗的肺部疾病,在急性加重期给予无创正压机械通气早期干预,可获得良好的疗效。我科在为60例COPD患者进行无创正压通气治疗时,出现以下不良反应,给予对应护理后,症状改善。现总结如下。     

慢性阻塞性肺疾病机械通气呼吸力学容积依赖性系数与内源性呼气末正压的相关性分析

目的探讨慢性阻塞性肺疾病(COPD)患者机械通气时呼吸力学非线性分析时呼吸系统弹性和阻力的容积依赖性系数(Evd/Rvd)与内源性呼气末正压(PEEPi)的相关性。方法2004年1月-2005年1月本院英东重症监护医学中心收治的25例COPD机械通气患者,分别以呼吸力学的线性和非线性模型分析其压力(P)、流量(V′)和容量(V)数据,比较二者的拟合效率指标决定系数(R2)和根均方差(RMSD);以呼气末阻断法测定PEEPi,分析弹性容积依赖性系数(Evd)、阻力容积依赖性系数(Rvd)以及Evd×Rvd与PEEPi的相关性。结果非线性分析所得的RMSD值(1.47±0.81)cmH2O小于线性分析所得(2.36±1.18)cmH2O;非线性分析所得的R2值(0.97±0.02)大于线性分析(0.89±0.08),差异均有统计学意义(P均<0.05);Evd、Rvd以及Evd×Rvd与PEEPi的相关系数分别为0.90、0.82和0.95(P均<0.01)。结论呼吸力学的非线性模型比线性模型更加适合COPD患者机械通气时呼吸力学分析。Evd和Rvd,特别是Evd×Rvd与PEEPi之间具有良好的相关性,或可用于COPD患者机械通气时PEEPi的无创性持续监测。     

应用BIPAP通气治疗慢性阻塞性肺疾病呼吸衰竭的体会

目的探讨基层医院开展双气道正压通气(BIPAP)疗法在慢性阻塞性肺疾病(COPD)呼吸衰竭患者治疗的应用价值. 方法分析了20例COPD Ⅱ型呼衰患者应用BIPAP通气,观察通气过程中症状体征变化,监测血气变化.结果除2例须中途停机转院治疗外,其余18例均取得较满意的疗效,气促减轻,呼吸频率减慢,辅助呼吸肌活动均减轻或消失.PaO2明显上升(p<0.01),PaCO2降低(p<0.01).18例平均住院天数缩短. 结论 BIPAP通气可改善缺氧,纠正二氧化碳潴留及呼吸性酸中毒,缩短住院时间,增加抢救成功率.     

Effect of expiratory positive airway pressure on sleep disordered breathing

STUDY OBJECTIVES: We sought to determine the effect of expiratory positive airway pressure on end expiratory lung volume (EELV) and sleep disordered breathing in obstructive sleep apnea patients. DESIGN: Observational physiology study PARTICIPANTS: We studied 10 OSA patients during sleep wearing a facial mask. We recorded 1 hour of NREM sleep without treatment (baseline) and 1 hour with 10 cm H2O EPAP in random order, while measuring EELV and breathing pattern. RESULTS: The mean EELV change between baseline and EPAP was only 13.3 mL (range 2-25 mL). Expiratory time was significantly increased with EPAP compared to baseline 2.64 +/- 0.54 vs 2.16 +/- 0.64 sec (P = 0.002). Total respiratory time was longer with EPAP than at baseline 4.44 +/- 1.47 sec vs 3.73 +/- 0.88 sec (P = 0.3), and minute ventilation was lower with EPAP vs baseline 7.9 +/- 4.17 L/min vs 9.05 +/- 2.85 L/min (P = 0.3). For baseline (no treatment) and EPAP respectively, the mean apnea+hypopnea index (AHI) was 62.6 +/- 28.7 and 56.8 +/- 30.3 events per hour (P = 0.4). CONCLUSION: In OSA patients during sleep, the application of 10 cm H2O EPAP led to prolongation of expiratory time with only marginal increases in FRC. These findings suggest important mechanisms exist to avoid hyperinflation during sleep.     

Assessment of mechanical ventilation parameters on respiratory mechanics

Better understanding of airway mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems in intensive-care medicine, as well as pulmonary medicine. Mechanical ventilation depends on several parameters, all of which affect the patient outcome. As there are no systematic numerical investigations of the role of mechanical ventilation parameters on airway mechanics, the objective of this study was to investigate the role of mechanical ventilation parameters on airway mechanics using coupled fluid-solid computational analysis. For the airway geometry of 3 to 5 generations considered, the simulation results showed that airflow velocity increased with increasing airflow rate. Airway pressure increased with increasing airflow rate, tidal volume and positive end-expiratory pressure (PEEP). Airway displacement and airway strains increased with increasing airflow rate, tidal volume and PEEP form mechanical ventilation. Among various waveforms considered, sine waveform provided the highest airflow velocity and airway pressure while descending waveform provided the lowest airway pressure, airway displacement and airway strains. These results combined with optimization suggest that it is possible to obtain a set of mechanical ventilation strategies to avoid lung injuries in patients.     

Differences in airway remodeling between asthma and chronic obstructive pulmonary disease

The functional consequence of asthma and chronic obstructive pulmonary disease (COPD) is airflow limitation, which is mostly reversible in asthma and not fully reversible in COPD. In both diseases, inflammatory conditions are associated with cellular and structural changes, referred to as remodeling, and these structural changes may lead to thickening of the airway wall, thereby promoting airway narrowing and airflow limitation. However, the pattern of infilatrated cells and the pattern of structural changes occur differently in the two diseases. In asthma, CD4+, T lymphocytes, eosinophils, and mast cells are the predominant cells involved, whereas COPD, CD8+, T lymphocytes, and macrophages are predominantly involved. In severe cases of asthma and COPD, neutrophil infiltration becomes evident. Regarding structural changes, epithelial injury and early thickening of reticular basement membrane are highly characteristic of the airway wall of asthmatics. Increases in airway smooth muscle mass occur in large airways of severe asthmatics and in small airways of patients with COPD. Thickening of the airway wall, golblet cell hyperplasia, mucous gland hypertrophy, and the luminal obstruction caused by inflammatory exudates and mucous are features of both asthma and COPD. Squamous epithelial metaplasia and airway wall fibrosis are commonly observed characteristics of COPD. Destruction and fibrosis of the alveolar wall occur in COPD but not in asthma. The remodeling processes accompanied by chronic inflammatory infiltrates interact in a complex fashion and contribute to the development of airflow limitation in both asthma and COPD.     

Complete respiratory support with AVCO2R and CPAP-mimic ventilation for total gas exchange in sheep

The altered respiratory mechanics in patients with chronic obstructive pulmonary disease (COPD) present unique challenges with regard to treatment during an acute exacerbation that often leads to respiratory support with mechanical ventilation. Alternative therapies are badly needed to reduce morbidity and mortality associated with mechanical ventilator use. We hypothesized that arteriovenous carbon dioxide removal (AVCO(2)R) coupled with continuous positive airway pressure (CPAP) would achieve total gas exchange eliminating the need for intubation/mechanical ventilation, thus reducing baro/volutrauma. This hypothesis was tested in six adult sedated apneic sheep with AVCO(2)R administered through a simple arteriovenous (AV) shunt for CO(2) removal. Because it is impractical to apply a CPAP mask to conscious sheep, the CPAP was mimicked in intubated/sedated sheep by positive end-expiratory pressure (PEEP) of 5-10 mmH(2)O with negligible ventilation. The AVCO(2)R and CPAP-mimic maintained Pa(o)(2) and Pa(co)(2) in the normal physiological ranges. The CO(2) removal was 120-150 ml/min through AVCO(2)R with AV blood flow of 1.1-1.5 L/min. A high fraction of inspired oxygen percentage (Fi(o)(2)) level (89 ± 3%) was required to achieve 40 ± 7% O(2) in the small bronchus. Thus, AVCO(2)R and CPAP-mimic achieved total gas exchange in anesthetized sheep and may be a potential option for acute COPD exacerbation in humans.     

双水平正压通气对慢阻肺患者行椎管内麻醉及手术时呼吸功能的影响

目的探讨双水平正压通气对慢性阻塞性肺疾病（COPD）患者在椎管内麻醉及手术中呼吸支持的效果。方法选择23例COPD合并Ⅱ型呼吸衰竭拟行下腹部或下肢手术的患者,腰-硬联合麻醉后行双水平正压（BiPAP）通气,BiPAP呼吸机采用S／T模式,设定呼吸频率为15次／min,吸气相压力（IPAP）为10～16cmH2O,呼气相压力（EPAP）为4cmH2O,吸入氧浓度为50％。监测无创血压、呼吸、心电图、脉搏氧饱和度、麻醉前、BiPAP通气后1h及脱机30min后的动脉血气值。结果患者BiPAP通气后动脉血二氧化碳分压（PaCO2）显著降低,从（62．6±13．1）mmHg降至（51．0±8．7）mmHg（P〈0．01）;动脉血氧分压（PaO2）显著增高,从（54．3±12．2）mmHg升至（71．4±14．5）mmHg（P〈0．01）;动脉血pH显著增高,从（7.31±0．09）升至（7．39±0．07）,（P〈0．01）;脱离BiPAP通气30min后动脉血气比麻醉前基础水平略有改善,但差异无统计学意义（P〉0．05）。结论双水平正压通气可明显改善COPD患者在低平面阻滞麻醉及手术期呼吸功能。     

OSAHS患者自然睡眠期呼吸模式对上气道流场的影响

目的分析阻塞性睡眠呼吸暂停低通气综合征(obstructive sleep apnea hypopnea syndrome,OSAHS)患者自然睡眠时平静呼吸和呼吸暂停期不同压力边界条件和呼吸模式对气道内气体的流动和生理状态的影响。方法创建OSAHS患者仰卧位自然睡眠状态,并采集CT数据建立三维上气道有限元模型。临床测量患者睡眠期喉腔压力作为边界条件,考虑鼻吸鼻呼、鼻吸口呼、口吸鼻呼、口吸口呼4种典型呼吸模式进行流体力学仿真。结果睡眠期OSAHS患者的呼吸气流呈非稳定、有涡、双向流动,压力边界以及呼吸模式对气体流动的影响明显。用口呼吸与用鼻呼吸相比,气体的最大流速有所升高,压降主要集中在口腔,吸气时升高约30%,呼气时升高1倍。结论采用OSAHS患者自然睡眠期CT数据建模并以临床喉腔压力作为边界条件进行有限元仿真具有意义,研究结果有助于了解OSAHS患者真实自然睡眠状态下的上气道流场特性。     

Practice parameters for the use of autotitrating continuous positive airway pressure devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome: an update for 2007. An American Academy of Sleep Medicine report

These practice parameters are an update of the previously published recommendations regarding the use of autotitrating positive airway pressure (APAP) devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome. Continuous positive airway pressure (CPAP) at an effective setting verified by attended polysomnography is a standard treatment for obstructive sleep apnea (OSA). APAP devices change the treatment pressure based on feedback from various patient measures such as airflow, pressure fluctuations, or measures of airway resistance. These devices may aid in the pressure titration process, address possible changes in pressure requirements throughout a given night and from night to night, aid in treatment of OSA when attended CPAP titration has not or cannot be accomplished, or improve patient comfort. A task force of the Standards of Practice Committee of the American Academy of Sleep Medicine has reviewed the literature published since the 2002 practice parameter on the use of APAP. Current recommendations follow: (1) APAP devices are not recommended to diagnose OSA; (2) patients with congestive heart failure, patients with significant lung disease such as chronic obstructive pulmonary disease; patients expected to have nocturnal arterial oxyhemoglobin desaturation due to conditions other than OSA (e.g., obesity hypoventilation syndrome); patients who do not snore (either naturally or as a result of palate surgery); and patients who have central sleep apnea syndromes are not currently candidates for APAP titration or treatment; (3) APAP devices are not currently recommended for split-night titration; (4) certain APAP devices may be used during attended titration with polysomnography to identify a single pressure for use with standard CPAP for treatment of moderate to severe OSA; (5) certain APAP devices may be initiated and used in the self-adjusting mode for unattended treatment of patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes); (6) certain APAP devices may be used in an unattended way to determine a fixed CPAP treatment pressure for patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes); (7) patients being treated with fixed CPAP on the basis of APAP titration or being treated with APAP must have close clinical follow-up to determine treatment effectiveness and safety; and (8) a reevaluation and, if necessary, a standard attended CPAP titration should be performed if symptoms do not resolve or the APAP treatment otherwise appears to lack efficacy.     

Constant mean airway pressure with different patterns of positive pressure breathing during the adult respiratory distress syndrome

Twenty-one ARDS patients were divided into two groups of severity according to FIO2 and PEEP required to maintain an adequate gas exchange. The 10 most severe patients (group A) underwent continuous positive pressure ventilation (CPPV) (I/E 3:1) with the mean airway pressure maintained at 21 +/- 6.2 cmH2O. The PEEP values were 12.6 +/- 4.3 cmH2O during CPPV and 6.5 +/- 3.7 cmH2O during IRV (p less than 0.01). Eleven less severe ARDS patients (group B) underwent CPPV and positive pressure spontaneous breathing (CPAP) at constant mean airway pressure of 14.3 +/- 3.8 cmH2O. The PEEP was 7 +/- 2.5 cmH2O during CPPV and 14.9 +/- 4.3 cmH2O during CPAP (p less than 0.001). In five patients of each group, the SF6 shunt was measured as representative of true shunt. The results showed that gas exchange, including true shunt, and haemodynamics did not change between CPPV and IRV and between CPPV and CPAP tests. Taken with previous work on mean airway pressure, our results further support the concept that the main determinant of oxygenation and haemodynamics is the mean airway pressure, irrespective of the PEEP level and of the mode of ventilation.     

典型男性OSAHS患者上气道气流运动特性的数值模拟

目的 研究典型男性阻塞性睡眠呼吸暂停低通气综合症（OSAHS）患者在平静呼吸时上气道气流运动特性,以及气流对软腭和悬雍垂作用的动力特点。方法 基于患者CT影像数据建立可靠的上气道流场几何模型,以临床睡眠监测数据作为数值模拟边界条件的依据,采用低雷诺数的湍流模型计算获得一个完整呼吸周期内上气道气流运动规律。结果OSAHS患者在呼吸过程中,上气道气流流动形式有显著差异。在吸气阶段,上气道腔内流速可达9.808 m/s,最大负压可达-78.856 Pa,鼻腔顶部出现局部回流,软腭受到的最大气流压力为-10.884 Pa,悬雍垂受到的最大气流压力为-51.946 Pa,气流对软腭和悬雍垂造成的最大剪切应力分别为78和311 mPa。在呼气阶段,上气道腔内最大流速为10.330 m/s,最大负压为-51.921 Pa,口咽部和鼻腔顶部均出现局部回流,且口咽部顺时针回流现象显著,软腭受到的最大气流压力为2.603 Pa,悬雍垂受到的最大气流压力为-18.222 Pa,软腭和悬雍垂受到的最大剪切应力分别为51和508 mPa。结论 口咽部是易塌陷的部位,一个呼吸循环过程的数值模拟可以捕捉到上气道流场显著的回流特征,上气道回流直接影响软腭和悬雍垂所受的力,同时也关系到患者呼吸的流畅程度。