适应性支持通气在部分支持通气中对呼吸力学和呼吸功的影响

目的探讨适应性支持通气(ASV)在部分支持通气过程中对呼吸力学和呼吸功的影响。方法30例有自主呼吸的危重症机械通气患者,在同样的分钟通气量和呼气末正压(PEEP)的设置下,先给予AC1模式通气45min后改为ASV模式通气,时间为45min,结束后改为AC2模式(参数设置与AC1一致),通气时间为45min。记录上述三个45min后的呼吸力学和呼吸做功的参数。结果ASV模式下的气道峰值压和平均气道压下降明显,P分别小于0.01和0.05。ASV下的内源性PEEP(PEEPi)发生率为23.3%,明显低于AC1的PEEPi发生率46.7%(P<0.05)。ASV的器械附加功(WOBimp)和吸气压力时间乘积(PTP)明显降低(P<0.01)。而两种呼吸模式的血气分析和血液动力学,以及前后两次AC模式的各种参数变化无统计学意义(P>0.05)。结论在危重症的部分支持机械通气过程中,ASV较常规通气模式有利于实施保护性通气策略,同时降低呼吸负荷和呼吸做功,因而能降低呼吸氧耗。     

持续气道正压通气,T管及压力支持通气等条件下患者呼吸功…

目的：探讨从呼吸功角度评价呼吸机脱机方式优劣的可能性及其意义。方法：通过Ｂｉｃｏｒｅ ＣＰ－１００呼吸监测测定２２例患者在压力支持通气（ＰＳＶ）、持续气道内正压（ＣＰＡＰ）通气、Ｔ管及拔管后２小时等条件下的呼吸功的变化。结果：ＣＰＡＰ０．４９ｋＰａ（１ｋＰａ＝１０．２０ｃｍＨ２Ｏ）Ｔ管、ＰＳＶ０．４９ｋＰａ时，患者呼吸功依次逐渐降低。ＣＰＡＰ０．４９ｋＰａ时呼吸功（９．９８Ｊ／ｍｉｎ）比ＰＳＶ０．     

呼吸功的评价及临床意义

呼吸功的评价及临床意义邱海波（综述）陈德昌（审校）作者单位：１００７３０中国医学科学院中国协和医院大学北京协和医院ＩＣＵ近年来，机械通气作为重要的器官功能支持手段，已广泛应用于临床。但呼吸支持的程度及何时脱机等仍是临床上常见的棘手问题。危重患者呼吸支...     

持续气道正压通气、T管及压力支持通气等条件下患者呼吸功的比较性研究

目的：探讨从呼吸功角度评价呼吸机脱机方式优劣的可能性及其意义。方法：通过ＢｉｃｏｒｅＣＰ１００呼吸监测仪测定２２例患者在压力支持通气（ＰＳＶ）、持续气道内正压（ＣＰＡＰ）通气、Ｔ管及拔管后２小时等条件下的呼吸功的变化。结果：ＣＰＡＰ０．４９ｋＰａ（１ｋＰａ＝１０．２０ｃｍＨ２Ｏ）、Ｔ管、ＰＳＶ０．４９ｋＰａ时，患者呼吸功依次逐渐降低。ＣＰＡＰ０．４９ｋＰａ时呼吸功（９．９８Ｊ／ｍｉｎ）比ＰＳＶ０．４９ｋＰａ时高２３．７％（Ｐ＜０．００１），比拔管后２小时高４８．５％（Ｐ＜０．０１），与Ｔ管时比较无显著性差异。Ｔ管时呼吸功（９．３１Ｊ／ｍｉｎ）比ＰＳＶ０．４９ｋＰａ时高１５．４％（Ｐ＜０．０５），比拔管后２小时高３８．５％（Ｐ＜０．０１）。结论：患者呼吸功因脱机方式不同而显著不同，ＰＳＶ０．４９ｋＰａ比ＣＰＡＰ０．４９ｋＰａ和Ｔ管更有利于脱机。     

呼吸功对机械通气患者撤机的指导意义

目的：研究呼吸功（ＷＯＢ）对机械通气患者撤机的指导意义。方法：选择机械通气并准备撤机的患者２３例，应用ＢＩＣＯＲＥＣＰ１００呼吸监测仪床边监测患者ＷＯＢ及常规撤机指标〔呼吸频率（ＲＲ）、潮气量（ＶＴ）、每分通气量（ＶＥ）和最大用力吸气时口腔闭合压（ＭＩＰ）〕，观察其对撤机的指导意义。结果：１８例撤机成功，其中１０例ＷＯＢ正常（≤０．７５Ｊ／Ｌ），８例ＷＯＢ升高（１．００Ｊ／Ｌ～１．３１Ｊ／Ｌ）；撤机失败患者５例的ＷＯＢ〔（１．９６±０．７６）Ｊ／Ｌ（１．４５Ｊ／Ｌ～２．８６Ｊ／Ｌ）〕明显高于撤机成功的患者〔（０．７７±０．３６）Ｊ／Ｌ，Ｐ＜０．０５〕。常规撤机指标ＲＲ、ＭＩＰ、ＶＥ均显著高于撤机成功组，ＶＴ显著低于撤机成功组。结论：ＷＯＢ值对撤机有一定的指导意义，但并非敏感指标，需考虑肺部基础疾病，结合临床指标等综合因素判断是否撤机。     

机械通气患者呼吸附加功影响因素的临床研究

目的　评价呼吸机、气管导管等器械阻力导致的附加功 (WOBimp)对患者呼吸功 (WOBp)的影响。方法　通过Ventrak 15 5 0呼吸监测仪 ,测定 18例患者不同机械通气条件下WOBp和WOBimp的变化。结果　持续气道正压 (CPAP) 5cmH2 O时 ,WOBp为 (10 14± 3 46 )J/min ,分别比压力支持通气 (PSV) 5cmH2 O和T管高 48 5 % (P <0 0 5 )和 2 3 7% (P >0 0 5 ) ,但比CPAP 0cmH2 O低 7 2 % (P >0 0 5 )。CPAP 5、 0cmH2 O和T管时 ,WOBimp占WOBp的比例分别为 5 8%、 5 1%和 42 %。CPAP 5cmH2 O时 ,WOBimp为 (0 78± 0 2 4)J/L ,分别比PSV 5cmH2 O〔(0 34± 0 13)J/L〕和T管〔(0 5 3± 0 14)J/L〕高 48 5 % (P <0 0 5 )和 2 3 7%(P <0 0 5 )。结论　呼吸机及气管导管导致的WOBimp使WOBp明显增加 ,气管导管是WOBimp明显增加的主要因素     

神经电活动辅助通气和压力支持通气对呼吸衰竭患者呼吸形式的影响

目的观察神经电活动辅助通气（NAVA）和压力支持通气（PSV）对急性呼吸衰竭患者呼吸形式的影响。 方法以2018年1月至2019年6月入住苏北人民医院ICU的12例急性呼吸衰竭行机械通气患者为研究对象,随机选择NAVA或PSV模式进行通气,NAVA和PSV通气支持水平均从5 cmH₂O（1 cmH₂O=0.098 kPa）开始,分4步递增,每10 min增加1次。PSV压力支持水平分别为5、10、15、20 cmH₂O,分别记为PSV1~4组。NAVA组的支持水平每10 min增加1倍,分别为起始NAVA支持水平的1、2、3、4倍,分别记为HAVA1~4组。观察不同支持条件下（PSV1~4组及NAVA1~4组）潮气量（V_T）、气道峰压（Ppeak）、呼吸机通气频率（VRR）、中枢呼吸频率（NRR）、膈肌电活动峰值（EAdipeak）、动脉血二氧化碳分压（PaCO₂）、无效触发发生情况、呼吸机送气时间（T_i-flow）、呼吸机呼气时间（T_e-flow）、神经吸气时间（T_i-neu）、神经呼气时间（T_e-neu）、总体V_T变异度等指标。 结果（1）随着通气支持水平的增加,PSV1~4组V_T、无效触发显著增加,VRR、NRR均明显减慢,组内比较差异均有统计学意义（F=13.471,F=30.521,F=13.672,F=9.357,P＜0.05）;PSV3~4组的V_T较同时点NAVA3~4组均显著增加,PSV4组无效触发显著高于NAVA4组,差异均有统计学意义（P＜0.05）;NAVA1~4组组内各时点的V_T比较,差异无统计学意义（P＞0.05）。（2）随着通气支持水平的增加,PSV1~4组组内各时点的T_i-neu,以及NAVA1~4组组内各时点的T_i-flow、T_e-flow、T_i-neu、T_e-neu均无显著增加,差异无统计学意义（P＞0.05）;PSV1~4组T_i-flow、T_e-flow、T_e-neu显著增加,组内比较差异均有统计学意义（F=9.564,F=13.431,F=21.126,P＜0.05）;PSV4组T_i-flow、T_e-flow、T_e-neu分别显著高于NAVA4组,差异均有统计学意义（P均＜0.05）。（3）NAVA组总体V_T变异度显著高于PSV组,差异有统计学意义（P＜0.05）;NAVA组Ppeak和EAdi显著相关（r=0.96±0.14,P＜0.05）。（4）PSV4组的PaCO₂较PSV1组显著降低,差异有统计学意义（P＜0.05）。 结论与PSV相比,NAVA通气支持时间、通气支持水平与自身呼吸形式更加匹配,对呼吸形式影响更小,一定程度上避免通气不足和过度通气。     

神经调节辅助通气对AECOPD患者呼吸功的影响

目的探讨不同外源性呼气末正压（extrinsic positive end expiratory pressure,PEEPe）条件下,神经调节辅助通气（neurally adjusted ventilatory assist,NAVA）对慢性阻塞性肺疾病急性加重（acute exacerbation of chronicobstructive pulmonary disease,AECOPD）患者呼吸功及触发功的影响。 方法以2012年5月至2013年5月入住东南大学附属中大医院ICU、静态内源性呼气末正压（intrinsic positive end-expiratory pressure,PEEPi）（PEEPi_stat）≥5 cm H2O（1 cm H2O=0.098 kPa）的AECOPD患者为研究对象。本研究方案已通过东南大学附属中大医院伦理委员会批准（批准号：2010ZDLL018.0）,并与患者签署了知情同意书。将控制通气下PEEPe由0升至40%PEEPi_stat,总呼气末正压（total-PEEP）不增加的患者作为呼气流速受限（expiratory flow limitation,EFL）组,增加的患者为呼气阻力（expiratory resistance,Re）增高组。共纳入AECOPD患者12例,其中EFL组6例,Re组6例。患者分组后调节镇静深度至Ramsay3分,在PEEPe设定为0、40%、80%、120%PEEPi_stat条件下,随机进行支持力度相同压力支持通气（pressure support ventilation,PSV）及NAVA通气。通过NAVA压力限定实现NAVA与PSV支持水平的等效性。监测食道内压（esophageal pressure,Pes）、膈肌电活动（electrical activity diaphragm,EAdi）,采集流速、压力波形并计算呼吸功（PTPes_ins）和触发功（PTPes_tri）。测量参数在通气模式和PEEPe水平之间的比较采用两因素的重复测量方差分析。在NAVA或PSV模式下,不同PEEPe水平之间的多重比较采用SNK检验。 结果2组患者年龄与急性生理与慢性健康评分II（acute physidogy and chronic health evaluation,APACHE II）等一般情况无显著差异。① NAVA与PSV支持水平的等效性：NAVA通气时可以获得与PSV通气类似的方波压力-时间曲线,且与PSV相比NAVA通气时呼吸频率、吸气时间、气道峰值压、平均气道压均无显著差异（t=0.720,0.817,0.621,1.579,均P>0.05）。② NAVA对呼吸功影响：在相同PEEPe水平下NAVA通气时呼吸功明显低于PSV通气（t=3.816,3.117,2.758,2.572,均P<0.05）。PEEPe由0逐渐增至120%PEEPi_stat时,在NAVA及PSV模式下,EFL组患者呼吸功均显著下降（t=4.629,4.431,4.165,5.082,均P<0.05）;RE组患者呼吸功无显著变化（F=8.12,7.64,均P>0.05）。③ NAVA对触发功的影响：相同PEEPe水平下,NAVA通气触发功明显低于PSV通气（t=4.624,4.431,4.165,5.082,均P<0.05）。PEEPe由0逐渐增至120%PEEPi_stat时,NAVA模式下EFL组及RE组患者触发功均无显著变化（F=5.71,5.93,均P>0.05）;PSV模式下,EFL组患者触发功显著下降（F=16.21,P<0.05）;RE组患者随着PEEPe增加触发功无明显变化（F=6.12,P>0.05）。 结论与PSV相比,NAVA通气显著降低AECOPD患者的呼吸功及触发功。NAVA通气时触发功不受PEEPe的影响,PSV通气时增加PEEPe可降低呼气流速受限患者的触发功。     

Effect of pressure support ventilation on breathing patterns and respiratory work

We assessed the effect of pressure support ventilation (PSV) on breathing patterns and the work of breathing in 10 postoperative patients. Minute ventilation ( _E) increased by 8% with 5 cm H₂O PSV and 10% with 10 cm H₂O PSV compared to 0 cm H₂O PSV. The increase in _E was achieved by increased mean inspiratory flow (24% with 5 cm H₂O PSV and 67% with 10 cm H₂O PSV) and a decrease in duty cycle (13% with 5 cm H₂O PSV and 39% with 10 cm H₂O PSV). The decrease in duty cycle along with a decrease in respiratory frequency allowed a greater expiratory time including a rest period for the respiratory muscles, which might minimize the risk of muscle fatigue. Furthermore, the inspiratory work added by the ventilator was near zero with 5 cm H₂O PSV and 10 cm H₂O PSV. Oxygen consumption also decreased significantly with 5 cm H₂O PSV. We conclude that PSV improves the breathing patterns and minimizes the work of breathing spontaneously via a ventilator.     

A comparison of the imposed work of breathing in continuous positive pressure ventilation mode between three different ventilators

Abstract Objective: To compare the work of breathing imposed and patient tolerance to the delivery of face mask continuous positive pressure ventilation by three different ventilators. Methods: Eleven healthy volunteers were subject to continuous positive pressure ventilation at levels of 0, 5, 10 and 15 cmH₂O on each of the three machines tested (Oxylog 2000, Drägerwerk AG, Lubeck, Germany; Puritan-Bennett 7200, Puritan Bennett Corp., Carlsbad, CA, USA; Auspap, Ulco Engineering Pty Ltd, Marrickville, NSW, Australia). The work of breathing imposed by the machines was measured using the Bicore-CP100 pulmonary function monitor (Allied Healthcare Products, CA, USA). After breathing on the three machines, volunteers rated the comfort of breathing on a visual analogue scale. Results: The work of breathing imposed by the Oxylog 2000 was higher in all volunteers receiving face mask continuous positive pressure ventilation when compared with both the Puritan-Bennett 7200 and the Auspap. The Oxylog 2000 was considered to be the least comfortable. Conclusions: The provision of continuous positive pressure ventilation in the emergency department is becoming increasingly common, but the use of a transport ventilator, such as the Oxylog 2000, to provide this ventilatory support cannot currently be recommended.     

Weaning from mechanical ventilation with pressure support in patients failing a T-tube trial of spontaneous breathing

Objective Evidence that PS may facilitate weaning from mechanical ventilation (MV), although not confirmed by randomized trials, prompted us to investigate whether patients could be weaned with PS after failing a T-tube trial.Design and setting This was a prospective, non-randomized study in two French intensive care units.Patients and participants One hundred eighteen patients were enrolled and underwent a T-tube trial, after which 87 were extubated. Thirty-one underwent a further trial with PS, after which 21 were extubated.Interventions All patients under MV >24 h meeting the criteria for a weaning test underwent a 30-min T-tube trial. If this was successful, they were immediately extubated. Otherwise, a 30-min trial with +7 cm H₂O PS was initiated with an individualized pressurization slope and trigger adjustment. If all weaning criteria were met, the patients were extubated; otherwise, MV was reinstated.Measurements and Results The extubation failure rate at 48 h did not differ significantly between the groups: 11/87 (13%) versus 4/21 (19%), P=0.39. The groups were comparable with regard to endotracheal tube diameter, MV duration, the use of non-invasive ventilation (NIV) after extubation, initial severity score, age and underlying pathology, except for COPD. A significantly higher percentage of patients with COPD was extubated after the trial with PS (8/21–38%) than after a single T-tube trial (11/87–13%) (P=0.003).Conclusions Of the patients, 21/118 (18%) could be extubated after a trial with PS, despite having failed a T-tube trial. The reintubation rate was not increased. This protocol may particularly benefit patients who are most difficult to wean, notably those with COPD.     

P0.1 is a useful parameter in setting the level of pressure support ventilation

Objective The purpose of this study was to investigate whether changes in breathing pattern, neuromuscular drive (P0.1), and the work involved in breathing might help to set the individual appropriate level of pressure support ventilation (PSV) in patients with acute respiratory failure (ARF) requiring ventilatory assistance.Design: A prospective, interventional study.Setting An 8-bed multidisciplinary intensive care unit (ICU).Patients Ten patients with ARF due to adult respiratory distress syndrome (ARDS), sepsis or airway infection were included in the study. Chronic obstructive pulmonary disease (COPD) patients with acute exacerbation were excluded. None of these patients was in the weaning process.Interventions We found a level of pressure support able to generate a condition of near-relaxation in each patient, as evidenced by work of breathing (WOB) values close to 0 J/l. This level was called PS 100 and baseline physiological measurements, namely, breathing pattern, P 0.1 and WOB were obtained. Pressure support was then reduced to 85%, 70% and 50% of the initial value and the same set of measurements was obtained.Measurements and results Flow ( ) was measured by a flow sensor (Varflex) positioned between the Y-piece of the breathing circuit and the endotracheal tube. Tidal volume was obtained by numerical integration of the flow signal. Airway pressure (P_aw) was sampled through a catheter attached to the flow sensor. Esophageal pressure (P_es) was measured with a nasogastric tube incorporating an esophageal balloon. The esophageal balloon and flow and pressure sensors were connected to a portable monitor (CP 100 Bicore) that provided realtime display of flow, volume, P_aw and P_es tracings and loops of P_es/V, P_aw/V and /V relationships. The breathing pattern was analyzed from the flow signal. Patient work of breathing (WOB) was calculated by integration of the area of the P_es/V loop. Respiratory drive (P 0.1) was measured at the esophageal pressure change during the first 100 ms of a breath, by the quasiocclusion technique. When pressure support was reduced, we found that the respiration rate significantly increased from PS 100 to PS85, but varied negligibly with lower pressure support levels. Tidal volume behaved in a similar way, decreasing significantly from PS 100 to PS85, but hardly changing at PS 70 and PS 50. In contrast, WOB and P 0.1 increased progressively with decreasing pressure support levels. The changes in WOB were significant at each stage in the trial, whereas P 0.1 increased significantly from PS 100 at other stages. Linear regression analysis revealed a highly positive, significant correlation between WOB and P 0.1 at decreasing PSV levels (r=0.87), whereas the correlation between WOB and ventilatory frequency was less significant (r=0.53). No other correlation was found.Conclusions During pressure support ventilation, P 0.1 may be a more sensitive parameter than the assessment of breathing pattern in setting the optimal level of pressure support in individual patients. Although P 0.1 was measured with an esophageal balloon in the present study, non-invasive techniques can also be used.     

Increased initial flow rate reduces inspiratory work of breathing during pressure support ventilation in patients with exacerbation of chronic obstructive pulmonary disease

Objective To investigate whether the level of initial flow rate alters the work of breathing in chronic obstructive pulmonary disease (COPD) patients ventilated in pressure support ventilation (PSV).Design Prospective study.Settings Medical ICU in University hospital.Patients Eleven intubated COPD patients.Methods We modulated the initial flow rate in order to achieve seven different sequences. In each sequence, the plateau pressure was reached within a predetermined time: 0.1, 0.25, 0.50, 0.75, 1, 1.25 or 1.50 s. The more rapidly the pressure plateau was achieved, the higher was the initial flow rate. In each patient, the pressure support level was an invariable parameter. The order of the seven sequences for each patient was determined randomly.Measurements and results Ten minutes after application of each initial flow rate, we measured the following parameters: inspiratory work of breathing, electromyogram (EMG) of the diaphragm (EMGdi), breathing pattern, and intrinsic positive end-expiratory pressure (PEEPi). Comparison between the means for each sequence and each variable measured was performed by two-way analysis of variance with internal comparisons between sequences by Duncan's test. The reduction of the initial flow rate induced a progressive increase in the values of the work of breathing, EMGdi, and mouth occlusion pressure (P 0.1). In contrast, the reduction of the initial flow rate did not induce any significant change in tidal volume, respiratory frequency or PEEPi.Conclusion As the objective of PSV is to reduce the work of breathing, it seems logical to use the highest initial flow rate to induce the lowest possible work of breathing in COPD ventilated patients.     

浅快呼吸指数在两种自主呼吸试验方法中的临床研究

目的 观察应用压力支持通气(PSV)和T管(T-piece)方法进行自主呼吸试验(SBT)时浅快呼吸指数(RSBI)及其变化水平(ΔRSBI)对脱机成功的预测作用.方法 将2007年1-12月本科经口气管插管机械通气(MV)可脱机的208例患者随机分为PSV组(93例)和T-piece组(115例),分别进行30 min的SBT,记录两组患者在SBT 3 min和30 min时的气道闭合压(P0.1)、呼吸频率(f)、潮气量(VT),计算RSBI值及ΔRSBI,寻找预测脱机成功的阈值.结果 208例患者脱机成功168例,成功率80.77%;PSV组和T-piece组成功率分别为83.87%和78.26%(P>0.05).SBT 30 min时PSV组和T-piece组RSBI分别为(67.18±11.55)次·min-1·L-1和(99.11±15.53)次·min-1·L-1(P<0.01);ΔRSBI分别为(69±33)%和(119±35)%(P<0.01).PSV组RSBI与脱机成功的受试者工作特征曲线(ROC曲线)下面积为0.747±0.045(P=0.000),当RSBI为75次·min-1·L-1时,诊断准确率为87%;ΔRSBI与脱机成功的ROC曲线下面积为0.709±0.065(P=0.001),当ΔRSBI为90%时,诊断准确率为82%,即在SBT结束时RSBI增加水平≤90%预测脱机成功较好.T-piece组RSBI与脱机成功的ROC曲线下面积为0.821±0.049(P=0.000),当RSBI为100次·min-1·L-1时,诊断准确率为82%;ΔRSBI与脱机成功的ROC曲线下面积为0.738±0.046(P=0.000);ΔRSBI为130%时,诊断准确率为77%,即在SBT结束时RSBI增加水平≤130%预测脱机成功较好.结论 PSV组SBT 30 min时RSBI明显小于T-piece组,其数值分别为75次·min-1·L-1和100次·min-1·L-1时预测脱机成功较好;动态观察RSBI的变化对预测脱机成功很有价值.     

Bedside measurement of work of breathing

This paper describes the technique of measuring work of breathing, presented at the 13th International Symposium on Computers in Clinical Medicine and Anaesthesiology, Rotterdam, June 1992. Measuring work of breathing.has clinical uses in the Intensive Care Unit. Oxygen consumption does not truly reflect work of breathing. Mechanical work of breathing can be measured by recording continuous pressure and flow and integrating the resultant power. This method is facilitated at the bedside with the use of a PC computer and a spreadsheet program. It is further simplified by software to measure the area under the inspiratory pressure: volume loop.     

压力支持通气与成比例压力支持通气模式对血流动力学状态的影响

目的　探讨压力支持通气 (PSV)与成比例压力支持通气 (PPS)不同通气模式对血流动力学的影响。方法　选择呼吸衰竭行机械通气及脉搏轮廓法持续血流动力学监护患者 2 6例。经治疗进入低辅助通气后比较在PSV、PPS两种通气模式下血流动力学及呼吸力学的差异。结果　PPS模式心输出量 (CO)、心指数 (CI)、每搏量 (SV)较PSV模式明显增加 (P <0 0 5 ) ,外周血管阻力 (SVR)无明显变化 (P >0 .0 5 ) ,气道峰压 (Ppeak)及内源性PEEP(PEEPi)明显下降 (P <0 .0 5 )。结论　PPS模式对机械通气患者的血流动力学状态影响最小 ,较适用于血流动力学不稳定患者。