无创正压通气治疗时不同呼气阀对二氧化碳重复呼吸的影响

呼气阀是无创正压通气（NIPPV）治疗时重要的呼气通路，是减少死腔通气，提高通气效率的重要无创呼吸机配件，临床常用的呼气阀有平台、侧孔和单向3种类型，本研究比较这3种呼气阀对面罩二氧化碳（CO2）重复呼吸的影响。     

无创正压通气在COPD、支气管哮喘和左心衰竭中的临床应用

无创正压通气(NPPV)是指通过鼻罩、口鼻罩或全面罩将患者与呼吸机相连的正压辅助通气.主要有双水平正压通气(BiPAP)和持续气道正压通气(CPAP)等通气方式.BiPAP是指在自主呼吸的吸气相和呼气相分别施加不同压力的通气方式,吸气压力(IPAP)主要用于增加肺泡通气,降低呼吸功和促进CO2排出;呼气压力(EPAP)相当于呼气末正压(PEEP),主要增加功能残气量,改善氧合.CPAP是始终保持气道正压的自主呼吸[1].无创正压通气广泛用于治疗慢性阻塞性肺疾病(COPD)、支气管哮喘、急性左心衰竭等疾病,在治疗过程中通过监测能代表疾病转归的治疗效果,本文就这一方面进展做一综述.     

不同呼吸频率机械通气对ARDS病人二氧化碳清除的影响

目的比较常规呼吸频率和高呼吸频率持续正压机械通气对急性呼吸窘迫综合征(ARDS)病人二氧化碳清除的影响。方法对16例ARDS病人入科后第一天给予有创机械通气,设置呼吸机模式为压力控制(PCV)。前后两次的控制压力及PEEPe设置相同(≤30cmH2O)且吸呼比(I∶E)不变。比较不同呼吸频率机械通气后的分钟通气量(MV);二氧化碳分压(PaCO2)、氧分压(PaO2);PEEPi;心脏指数(CI)、平均动脉血压(MBP)、中心静脉压(CVP)。结果与使用常规呼吸频率时比较,高呼吸频率通气时的分钟通气量虽然明显上升(P<0.05),但二氧化碳分压和氧分压无明显变化;内源性呼气末正压及中心静脉压有显著增高(P<0.05);在心脏指数、平均动脉血压方面有显著下降(P<0.05)。结论ARDS机械通气病人应用高呼吸频率并不能增加机体二氧化碳的清除,但导致内源性呼气末正压升高;同时降低心脏射血指数,影响血液动力学。     

喉罩联合不同压力肺复张肺保护性通气策略在老年患者全麻腹腔镜手术中的应用

目的探讨喉罩联合不同压力肺复张肺保护性通气策略在老年患者全麻腹腔镜手术中的应用。方法根据实验入选要求筛选合乎条件的自愿参加实验的手术患者,随机分为两组:对照组(C):喉罩联合常规保护性通气〔潮气量6 ml/kg,最佳呼气末正压(PEEP)<5 cmH 2O〕,实验组(E):喉罩联合驱动性压力肺复张压力通气(潮气量6 ml/kg,PEEP 5~10 cmH 2O)。比较两组全麻恢复期各组患者的血流动力学、呼吸功能指标、术后的肺部并发症(PPCs)及全身并发症发生情况。结果E组老年患者在全麻恢复期中各个血流动力学及呼吸功能指标皆优于C组。结论对于老年患者而言,全麻手术中采用喉罩联合驱动性压力肺复张压力通气肺复张肺保护性通气策略有提高肺功能恢复和降低并发症的可能。     

不同方式机械通气在急性左心衰竭临床应用中的疗效观察

目的探讨不同方式机械通气在急性左心衰竭临床应用中的疗效。方法选取我院2013年2月~2015年1月机械通气治疗的急性左心衰(ALVF)患者80例,根据患者入院时是否有意识模糊症状将其分为意识清醒组60例和意识模糊组20例。两组患者均应用利尿剂、血管活性药等常规治疗。意识清醒组采用经鼻面罩双相气道治疗,应用BIPAP呼吸机,调整模式为S/T,选择吸气压力(IPAP)10~18 cm H2O,呼气末压力选择4~8 cm H2O。意识模糊组采用气管插管机械通气,设置频率12~18次/min,潮气量8~10 ml/kg,呼吸时间比1:1.5~2。结果两组治疗1 h、6 h呼吸频率、心率、二氧化碳分压(Pa CO2)和平均动脉压(MAP)均明显降低,与治疗前比较,差异有统计学意义(P0.05),氧分压(Pa O2)较治疗前显著升高,差异有统计学意义(P0.05)。结论经鼻面罩无创正压通气和气管插管机械通气是治疗急性左心衰竭的有效措施,经鼻面罩无创正压通气主要适用于意识清醒的患者,气管插管机械通气主要适应于意识模糊的患者。     

多沙普仑联合无创正压通气治疗慢性阻塞性肺疾病急性加重期并发呼吸衰竭的临床意义

目的:探讨多沙普仑联合无创正压通气对慢性阻塞性肺疾病急性加重期(AECOPD)并发呼吸衰竭患者外周血中Th1/Th2、TREM-1的影响。方法:选择AECOPD伴呼吸衰竭患者80例,按照随机数字表法分为对照组和观察组,每组40例。对照组采用无创正压通气治疗,观察组予多沙普仑联合无创正压通气治疗。比较2组患者治疗前及治疗24 h后血气指标,检测治疗前和治疗结束后呼吸频率、潮气量和分钟通气量、血IL-2、IL-4、Th1/Th2及TREM-1水平,观察2组患者治疗期间不良反应发生情况。结果:治疗前2组患者的血气指标、呼吸频率、潮气量和分钟通气量、血IL-2、IL-4、Th1/Th2及TREM-1水平比较,差异无统计学意义(均P 0. 05),治疗后以上指标均得到不同程度的改善(均P 0. 05),其中观察组的Pa O2显著高于对照组,Pa CO2显著低于对照组,呼吸频率和分钟通气量显著高于对照组(均P 0. 05)。观察组的有创通气率及死亡率显著低于对照组(P 0. 05)。治疗后观察组的IL-2、Th1/Th2水平显著高于对照组,IL-4、TREM-1水平显著低于对照组(P 0. 05)。2组不良反应发生情况比较,差异无统计学意义(P 0. 05)。结论:多沙普仑联合无创正压通气治疗可改善AECOPD患者的血气指标,提高通气量,并具有一定安全性。     

面(鼻)罩压力支持加呼气末正压通气治疗慢性阻塞性肺疾病呼吸衰竭的生理效应

临床研究显示,无创正压通气(NIPPV)能改善慢性阻塞性肺疾病(COPD)患者慢性呼吸衰竭(以下简称呼衰)加重期的换气功能及呼吸方式。本研究通过观察面(鼻)罩压力支持通气(PSV)加呼气末正压(PEEP)通气治疗COPD患者慢性呼衰加重期的临床效应及生理效应,探讨如何选择适当的面(鼻)罩PSV水平,为临床合理应用NIPPV提供试验及理论依据。一、对象与方法1.选择明确诊断为COPD合并Ⅱ型呼衰急性加重期者,且满足pH>7.25、有自主呼吸意识、可配合面(鼻)罩通气、能自主排痰者26例,男10例,女16例,年龄(74.6±3.1)岁。诊断符合1997年中华医学会呼…     

平均容积保证压力支持与无创自动调节通气对高碳酸血症患者PaCO_2影响的比较

目的比较平均容积保证压力支持(AVAPS)与AVAPS无创自动调节呼气气道正压(AVAPS-AE)通气对重症高碳酸血症患者动脉血二氧化碳分压(PaCO_2)的影响。方法 50例高碳酸血症呼级衰竭患者分为两组,两组基础治疗相同,AVAPS-AE组(n=28)采用飞利浦伟康BiPAP A40呼吸机AVAPS-AE模式进行通气治疗,对照组(n=22)使用相同机型AVAPS模式通气治疗,比较两组间患者的入院时诊断情况、人口学特征、动脉血气值、目标潮气量设定和每天进行通气的时间。结果与对照组相比,AVAPS-AE组通气治疗6 h内PaCO_2显著下降(P0.05),PaCO_2和血浆内HCO_3~-水平在4 d内均显著下降(P0.01)。两组的平均可变吸气正压相似,但AVAPS-AE组的最大呼气正压、平均潮气量和漏气量都明显高于对照组(P0.05)。结论在ICU高碳酸血症呼吸衰竭患者中,AVAPS-AE模式较传统的AVAPS通气模式在降低PaCO_2方面更为有效和迅速。     

BiPAP在有创-无创序贯治疗中的临床观察

目的探讨双水平正压通气(BiPAP)无创呼吸机在呼吸衰竭气管切开患者序贯治疗中的可行性。方法选择15例呼吸衰竭气管切开机械通气患者,肺部感染基本控制,均有自主呼吸,生命体征稳定,呼吸机通气模式为压力支持、但撤机困难,应用双水平正压通气无创呼吸机,连接气管切开导管,行序惯呼吸支持治疗,观察呼吸机参数及患者呼吸频率、心率、血气分析,并于同期住院的15例呼吸衰竭患者经口鼻面罩行无创通气相比较。结果两组患者通气24、72 h吸气压、呼气压、潮气量、每分通气量、呼吸次数、心率、pH、PaO2、PaCO2无明显差异,但有创通气组漏气量明显减于无创通气组。结论 BiPAP无创呼吸机应用于稳病情定,但撤机困难的气管切开呼吸衰竭患者序贯治疗是可行、安全、有效的。     

BiPAP鼻罩式机械通气治疗左心衰竭

目的 探讨BiPAP鼻罩式双向正压机械通气治疗左心衰竭的疗效,适合的通气压力等具体方法,了解其对血液动力学的影响。方法 对35例各种病因所致严重左心衰竭患在常规药物治疗基础上采用BiPAP ST-D-20,ST-D-30呼吸机经鼻罩双向正压通气,以流量触发,压力支持,所以给吸气压8－15cm H2O,呼气压2－5cm H2O,氧浓度28－35％,患尽量闭口呼吸,对其中8例患插入Swan-Ganz漂浮热稀释导管,用HPMI166A型心电监护仪及配套血液动力学插件测定及计算各项血液动力学指标。同时与35例常规药物治疗组进行对比。结果 BiPAP组经鼻罩式机械通气后所有患呼吸频率减慢,心率下降,呼吸困难缓解,治疗总有效率为100％,对血压无明显影响,呼吸困难开始缓解时间为10min-3h,对8例BiPAP鼻罩式机械通气患血液动力学监测显示,平均肺动脉压和肺毛细血管楔压下降,心指数无明显变化,心搏指数增加,对照组在相应时间治疗总有效率仅为63．33％,结论 BiPAP鼻罩式双向正压机械通气是治疗左心衰竭的快速有效方法。     

Are tidal breathing indices useful in infant bronchial challenge tests?

Tidal breathing indices have been used to assess histamine-induced airway obstruction in adults and children. The aim of this study was to see whether they could be used to assess histamine challenge in infants. Tidal flow during quiet breathing was measured using a face mask and pneumotachograph and maximum flow at functional residual capacity (V_maxFRC) was measured from partial forced expirations in 18 sleeping, sedated infants who responded to histamine challenge and in 18 nonresponders. The tidal indices calculated were inspiratory and expiratory time (t₁, and t_e), tidal peak expiratory flow (PEF), mean tidal expiratory flow rate (V_T/t_e) and the expiratory time constant of the respiratory system (t_rs). The time to maximal expiration divided by expiratory time (t_me/t_e) and 2 revised forms of this index (t_me(a)t_e and t_me(b)( t_me(b) /t_e) were also calculated. Recordings of t_me(a) and t_me(b) were taken at 95% of peak tidal expiratory flow, before and after the peak, respectively. In nonresponders, there was an insignificant mean rise in V_maxFRC of 11.8% but no change in any tidal index. In responders, the mean percentage fall in V_maxFRC was 43.3% (range, ?31 to ?81%); t_rs fell from 0.61 s to 0.51 s (P < 0.05) and breathing frequency and mean tidal expiratory flow rate increased from 34.0 to 37.5 min^?1 (P < 0.01) and from 66.6 to 72.6 mL.s^?1 (P < 0.05), respectively, suggesting that infants had adopted a strategy of active expiration in response to bronchial challenge. There was no change either in t_me/t_e, or in the revised indices after challenge., It is therefore concluded that t_me/t_e is an insensitive index of airflow obstruction compared to V_maxFRC and cannot be used to assess the response to bronchial challenge. Changes in other indices were small and related to a presumed pattern of active expiration after challenge. Pediatr Pulmonol. 1994; 17:225–230. © 1994 Wiley-Liss, Inc.     

Exploring the relationship between forced maximal flow at functional residual capacity and parameters of forced expiration from raised lung volume in healthy infants

The raised volume rapid thoraco-abdominal compression technique (RVRTC) is being increasingly used to assess airway function in infants, but as yet no consensus exists regarding the equipment, methods, or analysis of recorded data. The aim of this study was to explore the relationship between maximal flow at functional residual capacity (V'(maxFRC)) and parameters derived from raised lung volumes, and to address analytical aspects of the latter technique in an attempt to assist with future standardization initiatives. Forced vital capacity (FVC) from lung volume raised to 3 kPa, timed forced expiratory volumes (FEV(t)), and forced expiratory flow parameters at different percentages of expired FVC (FEF(%)) were measured in 98 healthy infants (1-69 weeks of age). V'(maxFRC) using the tidal rapid thoraco-abdominal compression (RTC) technique was also measured. The within-subject relationships and within-subject variability of the various parameters were assessed.Duration of forced expiration was < 0.5 sec in 5 infants, meaning that FEV(0.3) and FEV(0.4) were the only timed volume parameters that could be calculated in all infants during the first months of life, and even when it could be calculated, FEV(0.5) approached FVC in many of these infants. It is recommended that FEV(0.4) be routinely reported in infants less than 3 months of age. Contrary to previous reports, within subject variability of V'(maxFRC) was less than that of FEF(75) (mean CV = 6.3% and 8.9%, respectively).A more standardized protocol when analyzing data from the RVRTC would facilitate comparisons of results between centers in the future.     

Symptom perception and functional morbidity across a 1-year follow-up in pediatric asthma

The purpose of this study was to examine the association between asthma symptom perception measured during a 5-6 week baseline and functional morbidity measured prospectively across a 1-year follow-up. Symptom perception was measured by comparing subjective ratings with peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV(1)). We hypothesized that accurate symptom perception (ASP) would be associated with less functional morbidity. Participants consisted of 198 children with asthma ages 7-17 recruited from three sites. The children used a programmable electronic spirometer in the home setting to guess their PEFR prior to exhalation. Each "subjective" guess was classified as being in an ASP, dangerous symptom perception (DSP; underestimation of symptoms), or symptom magnification (SM; overestimation) zone based upon the corresponding measurement of PEFR or FEV(1). An index of functional morbidity was collected by parent report at baseline and across 1-year follow-up. A greater proportion of ASP blows and a lower proportion of DSP blows based on PEFR predicted less functional morbidity reported at baseline, independent of asthma severity and race/ethnicity. A greater proportion of ASP blows (using PEFR and FEV(1)) and a lower proportion of SM blows (using FEV(1)) predicted less functional morbidity across 1-year follow-up. Symptom perception was not associated with emergency department visits for asthma at baseline or across follow-up. In comparison to PEFR, FEV(1) more frequently detected a decline in pulmonary function that children did not report. Symptom perception measured in naturalistic settings was associated with functional morbidity at baseline and prospectively across 1-year follow-up. Support was found for including multiple measures of pulmonary function in the assessment of asthma symptom perception.     

Validation of respiratory inductance plethysmography ("Respitrace") for the measurement of tidal breathing parameters in newborns.

INTRODUCTION: The ratio of the time to reach peak (maximum) tidal expiratory flow (Tme) to total expiratory time (Te) is smaller in infants who later develop lower respiratory tract disease. In previous studies infants have been sedated and flow measured using a pneumotachograph with face-mask. These methodological factors are known to affect tidal breathing, and the frequent need for sedation limits the use of the technique to relatively small studies. The aim of this study was to validate uncalibrated respiratory inductance plethysmography (Respitrace) to measure Tme/Te in unsedated newborns. METHODS: Nineteen normal term infants were studied during quiet sleep. Agreement between Tme/Te measured directly using a pneumotachograph and with Respitrace was assessed in 15 infants. Repeatability of the Respitrace technique was assessed in 10 infants. RESULTS: The mean Tme/Te for the 19 infants using Respitrace was 0.46 (S.D. 0.14). The mean difference between Tme/Te obtained using Respitrace and that measured with a pneumotachograph was 0.014; 95% of Respitrace readings were between -0.042 and 0.070 of the pneumotachograph values. The mean difference between repeat Respitrace values was 0.02 with 95% of the second measurements within 0.066 of the first. CONCLUSIONS: These results indicate that Respitrace can be used to determine Tme/Te accurately.     

Assessment of a low-cost home monitoring spirometer for children

Electronic devices are now available to measure and store lung function parameters in the home. Before adopting a device for clinical or research use, it is important to validate it in the target patient group. The aim of this study was to assess a low-cost, portable, logging spirometer, the VM Plus (VM), against a standard laboratory Jaeger spirometer (JS) for use in children with respiratory disease. Seventy children with stable asthma or cystic fibrosis performed spirometry on the two devices, and results for peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) were compared. Comparison was made both using the two devices separately (separate method) and with the devices connected in series (series method). Reproducibility of the VM measurements was also assessed. Correlation between measurements was close (R values: separate, PEF, 0.91; FEV(1), 0.94; series, PEF, 0.97, FEV(1), 0.99), but PEF readings on the VM Plus were substantially higher than with the JS (mean difference: separate, 54.8 L/min; series, 28.2 L/min). This reflects well-reported differences in PEF measurements between the Mini-Wright PEF meter, on which the VM Plus spirometer is based, and conventional spirometers. Limits of agreement (series method) were: PEF, -13.2 to +69.6 L/min; FEV(1), -0.03 to +0.19 L. Reproducibility of VM Plus measurements was acceptable: coefficient of variation for PEF was 4%; for FEV(1), 4.3%; coefficient of reproducibility for PEF, 39 L/min; for FEV(1), 0.26 L. The VM Plus provides reasonably accurate, reproducible measurements of PEF and FEV(1), but intrinsic bias, particularly in PEF measurement, needs to be taken into account. Its potential to document longitudinal changes in lung function in children with respiratory disease at home merits further study.     

Tracheal diameter as a predictor of pulmonary function

Tracheal diameter (TD) was measured from standard posterior-anterior (PA) roentgenograms and evaluated as a predictor of pulmonary function. A population of 222 non-smokers with normal chest roentgenograms was analyzed. A subset of the population with the trachea indented two or more mm by the aorta (on PA film), as well as males and females, were analyzed separately. In males without aortic indentation of the trachea, tracheal diameter alone accounted for 28% of the variation in peak expiratory flow rate (PEFR). Age and height accounted for an additional 19% of the variation. Tracheal diameter was second to age as a predictor for forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC), accounting for an additional 10% of the variation in each. However, tracheal diameter did not explain significant variability in the female group. This study supports an upper airway effect on flow at large lung volumes. It also demonstrates that a tracheal diameter, measured from a PA chest film, is a useful predictor of pulmonary function that can be easily applied in population surveys.     

Maximal expiratory flow in the guinea pig

Using the whole body plethysmograph, the maximal expiratory flow-volume (MEFV) curve was performed in anesthetized-paralyzed guinea pigs with intact chest (n = 7) and in anesthetized, chest-open animals following exsanguination (n = 13). The pressure-volume (PV) curve was also measured. Before and after the MEFV and PV maneuvers, lung volume was determined with a neon dilution method. Peak maximal expiratory flow of 178 ± 7 ml/sec occurring at 83% TLC. After the peak flow, decreased gradually with reducing lung volume. The -static recoil pressure curve was relatively linear up to P_L = 5 cmH₂O. Density-dependence of (helium- was significantly higher than air- ) was found at or above 60% TLC but not at lung volume below 60% TLC. For the chest-open postmortem guinea pig, and TLC decreased while trapped gas volume increased gradually with time after exsanguination, indicating that bronchoconstriction gradually became more severe. The magnitude of this postmortem airway spasm was related to age and anesthetic used.     

Effect of body position on maximal expiratory pressure and flow in adults with cystic fibrosis

Maximum expiratory pressure (MEP) and peak expiratory flow rate (PEFR) are used as surrogate measures of cough and huff strength. Some body positions (particularly head-down tilt) significantly affect these measures in people with normal respiratory function and with chronic obstructive pulmonary disease. This may have implications for people with cystic fibrosis (CF), who use coughing and huffing and may use gravity-assisted drainage positions for airway clearance. Previous research concluded that body position does not affect MEP in people with CF, although head-down tilt was not examined and PEFR was not measured. This study investigated the effect of body position on MEP and PEFR in 20 adults with stable CF. Repeated measures of MEP and PEFR were performed across seven positions (standing, chair-sitting, sitting in bed with backrest vertical, sitting in bed with backrest at 45 degrees , supine, side-lying, and side-lying with head-down tilt 20 degrees ) in random order. During testing, reflux sensation and oxygenation were monitored. MEP was significantly reduced in side-lying and in the head-down tilt position. PEFRs were significantly reduced in the three-quarters sitting, supine, side-lying, and head-down positions. Oxygenation and reflux scores were worst in the head-down position. Despite statistical significance, the differences observed between positions in this stable population were of small magnitude. The effect of body position on MEP and PEFR may be more relevant during airway clearance treatments of the acutely unwell person with CF.     

A computer-model analysis of the influence of the upper airway on passive flow-volume loops in infants

The present study was undertaken to determine the effects of upper airway resistance (Rua) and elastance (Eua) on the mechanical parameters calculated from the expiratory limb of the passive flow-volume curve in normal infants, using a computer model. The model included separate compartments for the respiratory system, upper airway, and measurement equipment. Inclusion of Rua in the model decreased the slope of the expiratory limb of the flow-volume loop, and the resistance calculated from the flow-volume loop accurately reflected the total resistance of the model. Inclusion of Eua in the model caused a decrease in the end-inspiratory (driving) pressure and a corresponding decrease in the peak expiratory flow but did not alter the slope of the linear portion of the expiratory limb of the flow-volume loop. Resistance calculated from the loop underestimated true model resistance by 14.5%. However, further small fluctuations in Eua did not cause significant variability in the value of resistance calculated. Total elastance was accurately calculated whether or not Rua and Eua were included in the model. The results of this analysis demonstrate that, while Eua causes the true resistance to be underestimated, fluctuations in Eua are not likely to be an important source of variability in the mechanical parameters calculated from the passive flow-volume loop; however, any changes in Rua will be reflected in the value of resistance calculated and therefore are likely to cause substantial variability in the calculated resistance.     

Maximal expiratory flow at FRC (V'maxFRC): Methods of selection and differences in reported values

We compared three methods of reporting maximal expiratory flow (V'maxFRC) measured in partial expiratory flow-volume curves (PEFVCs) at the point of functional residual capacity (FRC). PEFVCs were obtained with the rapid thoracoabdominal compression technique (RTC) on a total of 446 occasions in 281 HIV-negative, asymptomatic infants (4.8-28.1 months old). Three different expressions of V'maxFRC were recorded: 1) the highest measured flow (maxV'FRC), 2) the mean of the three highest flows (mean3V'FRC), and 3) the flow at FRC in a composite curve (compV'FRC) consisting of PEFVCs, obtained at different jacket pressures and superimposed at their distal limb. The numerical value of maxV'FRC was 7.4% (+/-5.6%) higher than the mean3V'FRC, and 11.9% (+/-17.7%) higher than the compV'FRC; the mean3V'FRC was 5% (+/-18.3%) higher than the compV'FRC. Bland-Altman analysis was used to evaluate the agreement between the three indices. The mean difference and 95% limits of agreement were: maxV'FRC -mean3V'FRC, 14 +/- 18 ml/sec; maxV'FRC - compV'(FRC), 23 +/- 58 ml/sec; and mean3V'(FRC) - compV'(FRC), 10 +/- 52 ml/sec. The differences between the slopes of the three indices (regressed against height) were statistically significant, although clinically unimportant. We conclude that despite their high correlation, the mean3V'FRC and maxV'FRC should not be used interchangeably, and that the composite analysis, although useful, does not improve the reproducibility of V'maxFRC, and thus it cannot be recommended for routine use in its current form.