PEEP和CPAP在电视辅助胸腔镜手术行单肺通气时对氧合作用及分流的影响

目的 评价呼气末正压通气(PEEP)和连续气道正压通气(CPAP)在电视辅助胸腔镜手术(VATS)行单肺通气麻醉时对患者血氧合作用的影响。方法 选择30例在VATS下行肺叶切除的单纯肺癌患者,随机分为A、B两组。A组于手术开始后15min(A1)、单肺通气后15min(Az)、患侧肺0cmH2OPEEP健侧肺5cmH2OPEEP后15min(A3)、患侧肺5cmH2OCPAP健侧肺0cmH2OPEEP后15min(A4)、患侧肺5cmH2OCPAP健侧肺5cmH2OPEEP后15min(A5)分别监测平均肺动脉压(PAP)、平均动脉压(MAP)、心率(HR)、动脉血氧分压(PaO2)、混合静脉血氧分压(RVO2)、动脉血氧饱和度(SaO2)、混和静脉血氧饱和度(SVO2)并计算分流(Qs／Qt)值。B组用10cmH2OPEEP和10cmH2OCPAP重复上述过程。结果 与A2相比,A3、A4和A5PaO2显著增加,Qs／Qt值显著降低(P＜0．05),但A3、A4、A5间相比较则无显著性差异(P＞0．05)。B组各时点的各项指标变化与A组类同。结论 在VATS行单肺通气麻醉时,健肺使用PEEP、患肺使用CPAP或联合使用PEEP和CPAP能提高患者手术中的氧合作用,降低Qs／Qt值;与5cmH2O PEEP和CPAP比较,10cmH2O PEEP和CPAP不能进一步改善PaO2和Qs／Qt。     

不同水平呼气末正压通气对头低位腹腔镜手术患者肺顺应性及肺氧合的影响

目的 观察不同呼气末正压通气(positive end-expiratory pressure,PEEP)对头低位腹腔镜手术患者的肺顺应性及肺氧合的影响,探讨在头低位腹腔镜手术施行PEEP的合适水平. 方法 选择ASA分级Ⅰ、Ⅱ级,择期行腹腔镜直结肠手术患者45例,根据随机数字表法分成3组(每组15例):Ⅰ组,PEEP=0;Ⅱ组,PEEP=4 cmH2O(1 cmH2O=0.098 kPa);Ⅲ组,PEEP=8 cmH2O.术中采用容量控制通气,维持PETCO2 35～45 mmHg(1 mmHg=0.133 kPa),记录麻醉诱导后即刻(T0)、手术开始后10 min(T1)、各组实施不同水平PEEP干预后30 min (T2)和60 min(T3)、手术结束拔管前10 min(T4)的PETCO2、肺动态顺应性(pulmonary dynamic compliance,Cdyn),并同时抽取动脉血和深静脉血行血气分析,计算死腔通气比(dead space ventilationratio,Vd/Vt)和肺内分流率(intrapulmonary shunt,Qs/Qt). 结果 3组患者一般资料、HR及MAP差异无统计学意义(P＞0.05).3组患者Cdyn在T1时较T0时均降低(P＜0.05),Ⅱ组和Ⅲ组在T2时上升,在T4时[Ⅱ组(50.9±9.8) ml/cmH2O,Ⅲ组(58.8±13.4) ml/cmH2O]高于T0时[Ⅱ组(47.6±10.6) ml/cmH2O,Ⅲ组(51.3±10.8) ml/cmH2O](P＜0.05),Ⅲ组在T2、T3时高于Ⅰ组[T2:Ⅲ组(42.8±9.9) ml/cmH2O,Ⅰ组(29.3±8.0) ml/cmH2O;T3:Ⅲ组(42.9±10.3) ml/cmH2O,Ⅰ组(29.3±8.6) m]/cmH2O] (P＜0.05).3组的Vd/Vt在T1时均增大(P＜0.05),Ⅰ组和Ⅲ组在T4时[Ⅰ组(21.5±7.6)％,Ⅲ组(24.2±6.8)％]高于T0时[Ⅰ组(9.5±5.8)％,Ⅲ组(10.7±5.2)％](P＜0.05),而Ⅱ组在T4时[(12.2±6.8)％]同T0时[(9.9±7.8)％]比较,差异无统计学意义(P＞0.05),且低于同一时点Ⅰ组和Ⅲ组(P＜0.05).Ⅱ组的Qs/Qt在T4时低于Ⅰ组[Ⅱ组(12.3±6.3)％,Ⅰ组(26.2±20.8)％](P＜0.05).中心静脉血氧分压(central venous partial pressure of oxygen,PvO2)3组均逐渐上升(P＜0.05).Ⅱ组在T4时PaO2和PvO2均高于其他两组(P＜0.05). 结论 PEEP有利于头低位腹腔镜手术患者的肺顺应性及肺氧合.4 cmH2O PEEP不仅能改善肺顺应性,更有利于降低Vd/Vt和Qs/Qt,增加肺氧合.     

经胸腔镜肺大泡切除术中应用单肺通气对血气及血液动力学的影响

目的　观察胸腔镜手术中单肺通气时应用不同水平的呼气末正压通气 (PEEP)对血气及血液动力学的影响。方法　随机选择胸腔镜肺大泡切除术病人 36例 ,均分为三组 :A组为单肺间歇正压通气 (IPPV)通气 ;B组为单肺IPPV加PEEP 5cmH2 O通气 ;C组为单肺IPPV加PEEP10cmH2 O通气。分别记录平卧位双肺通气、侧卧位双肺通气、单肺通气 10min和 30min四个时点的血气和血液动力学参数。结果　各组病人SpO2 始终维持在 99%～ 10 0 %。动脉血氧分压 (PaO2 )也在正常范围 ,但B、C组明显高于A组 (P <0 .0 5 )。其余血气指标无明显变化。三组病人HR、MAP、左心室射血时间 (LVET)及体循环血管阻力 (SVR)均无明显变化。B、C组在单肺通气 10min及 30min后 ,每搏量 (SV)及心输出量 (CO)下降明显 ,但均在正常范围 ,且无组间差异。体位改变时血液动力学稳定。结论　经胸腔镜肺大泡切除术中单肺IPPV、PEEP 5cmH2 O均能维持满意的PaO2 和动脉血二氧化碳分压 (PaCO2 ) ,血液动力学变化不显著 ;但PEEP 5cmH2 O较IPPV能进一步提高PaO2 ,PEEP 10cmH2 O不能较PEEP 5cmH2 O进一步提高PaO2 。     

七氟醚和丙泊酚在小潮气量联合低呼气末正压对单肺通气时肺内分流、氧合和炎性因子的影响比较

目的 比较单肺通气过程中,七氟醚和丙泊酚对实施小潮气量联合低呼气末正压通气(positive end-expiratorypressure,PEEP)患者肺内分流、氧合和炎性因子的影响.方法 择期行右侧开胸手术的食管癌患者76例,美国麻醉医师协会(ASA)分级Ⅰ～Ⅲ级,采用随机数字表法将患者分为丙泊酚组(P组)和七氟醚组(S组),每组38例.P组持续输注丙泊酚,S组持续吸入七氟醚,维持脑电双频指数(bispectal index,BIS)40～50,其他用药两组相同.分别在手术开始前(T0)和单肺通气后30(T1)、60(T2)、90 min(T3)以及膨肺后双肺通气30(T4)、60 min(T5),采集颈内静脉和桡动脉血样进行血气分析,计算肺内分流率(Qs/Qt)、相邻两个时间点动脉血氧分压(arterial partial pressure of oxygen,PaO2)和Qs/Qt的变化值(△PaO2和△Qs/Qt),并测定白细胞介素(interleukin,IL)-8、IL-10和肿瘤坏死因子(tumor necrosis factor,TNF)-α的浓度.结果 与T0比较:两组T1～T5时Qs/Qt、IL-8、IL-10、TNF-α均升高,PaO2降低(P＜0.05).与T1比较:两组T4、T5时PaO2明显升高,Qs/Qt明显降低(P＜0.05);P组IL-8、IL-10、TNF-α在T3～T5时升高,而S组在T2～T5时升高(P＜0.05).两组间比较:△PaO2[P组(-1.3±7.7)、(-1.9±6.0),S组(-4.3±4.3)、(-3.1±5.3)]和△Qs/Qt[P组(0.06-±0.57)、(0.07±0.34),S组(0.71±0.86)、(0.72±0.95)]在T1～T2、T2～T3时间段比较差异均有统计学意义(P＜0.05),S组IL-8、IL-10、TNF-α在T2～T5时均高于P组(P＜0.05).结论 单肺通气期间实施小潮气量联合低PEEP时,丙泊酚比七氟醚对肺内分流和氧合影响更小,产生炎性因子少.     

反比通气联合PEEP对肺叶切除患者单肺通气时肺功能的影响

目的探讨反比通气联合PEEP对肺叶切除患者单肺通气时肺功能及炎症因子的影响。方法选择择期行肺叶切除术单肺通气的患者80例,男52例,女28例,年龄37~65岁,BMI21~29kg/m~2,ASAⅡ级,随机分为反比通气组与常规通气组,每组40例。支气管插管全麻后机械通气,反比通气组为I∶E 2∶1,VT7mL/kg,RR 12次/分,PEEP 5mH_2O;常规通气组为I∶E 1∶2,其他参数不变。记录麻醉前(T0)、麻醉后5min(T_1)、单肺通气开始(T_2)、单肺通气45 min(T_3)及手术结束(T4)的呼吸力学指标,采集T_0、T_3时的动脉血和中心静脉血进行血气分析,计算氧合指数(OI)。用纤维支气管镜采集T_1、T_3时支气管肺泡灌洗液,采用ELISA法检测IL-6、IL-8及IL-10浓度的变化。结果与常规通气组比较,T_3时反比通气组PaO_2明显升高(P0.05);T1~T4时反比通气组气道峰压(Ppeak)和气道平台压(Pplat)明显降低(P0.05),PEEP和平均气道压(Pmean)明显升高(P0.05),肺的顺应性(CL)明显增加(P0.05);T3时反比通气组IL-6、IL-8和IL-10浓度明显降低(P0.05)。低氧血症常规通气组2例(5.0%),反比通气组1例(2.5%),两组差异无统计学意义。两组均未见苏醒延迟、肺不张和气胸等并发症。结论反比通气联合PEEP可改善通气和低氧血症,增加肺的顺应性,降低气道平台压,抑制炎症因子释放。     

肺复张策略对健侧肺氧合及顺应性的影响

目的 评价肺复张策略(lung recruitment maneuvers,LRM)对健侧肺氧合及顺应性的影响. 方法 ASA分级Ⅱ级择期行胸腔镜辅助下肺切除术患者40例,采用随机数字表法分为对照组(C组)和实验组(L组),每组20例.C组术中常规单肺通气(one lung ventilation,OLV),L组OLV 20 min后进行1次LRM,两组均在OLV结束关闭胸腔前进行1次肺复张.分别于患者麻醉前(T0),OLV后20 min(T1),LRM后15 min(T2)、30 min(T3)、45 min(T4)及OLV结束(T5)时,采集患者生命体征数据并采集动脉血样本进行血气分析,根据公式计算肺顺应性(dynamic compliance,Cdyn). 结果 与C组相比,L组PaO2在T2[(150±11) mmHg比(204±21) mmHg,1 mmHg=0.133 kPa]、T3[(154±12) mmHg比(176±14) mmHg]、T5[(442±20) mmHg比(473±15) mmHg]时点均升高(P＜0.05),Cdyn在T2[(21±3) ml/cmH2O比(25±3) ml/cmH2O,1 cmH2O=0.098 kPa]和T5[(26±3) ml/cmH2O比(31±5)ml/cmH2O)]时点提高(P＜0.05). 结论 LRM可以有效改善OLV期间氧合及Cdyn,单次LRM提高PaO2有效时间为30 min,在15 min左右PaO2改善最为明显.     

不同压力持续气道正压对单肺通气氧化应激反应的影响

目的比较不同压力持续气道正压(CPAP)对单肺通气氧化应激反应的影响。方法择期行食管癌根治术患者48例,随机均分为双肺通气组(A组)、单肺通气组(B组)、单肺通气非通气肺给予2cmH2OCPAP组(C组)及5cmH2OCPAP组(D组)。分别于开胸前(T0)、单肺通气后(A组于开胸后)30min(T1)、90min(T2)、150min(T3)、手术结束(T4)时测定血清超氧化物歧化酶(SOD)活性、丙二醛(MDA)、NO浓度。结果 T1～T4时B、C组及T2～T4时D组的SOD活性明显低于A组,T1～T4时B、C、D组MDA及NO浓度高于A组(P0.05)。T1～T4时C、D组MDA及NO浓度均显著低于B组(P0.05),T3时C、D组SOD活性显著高于B组(P0.05);T3时D组MDA及NO浓度高于C组(P0.05)。结论 CPAP能减轻单肺通气氧化应激反应,且2cmH2OCPAP优于5cmH2OCPAP。     

高呼气末正压小潮气量通气对肺功能正常患者血流动力学的影响

目的 观察肺功能正常的患者术后使用不同水平呼气末正压(PEEP)小潮气量通气对血流动力学的影响.方法 102例ASA Ⅰ或Ⅱ级,择期全麻下耳鼻喉科术后患者,随机均分为六组.研究组使用保护性肺通气模式,潮气量5 ml/kg,根据PEEP 0、5、10、15和20 emH2O分为P0、P5、P10、P15和P20.五组.对照组(C组)使用常规机械通气模式,潮气量10 ml/kg.观察保护性肺通气前(T1)及保护性肺通气30 min后(T2)的血流动力学的改变.结果 与C组及T1时比较,T2时加速度指数(ACI)在P0、P5、P10和P15组升高,P20组降低;心脏指数(CI)、左室做功指数(LCWI)、平均动脉压(MAP)在P20组降低(P＜0.05);胸腔液体水平(TFC)P10P15和P20组T2时明显低于T1时(P＜0.05).结论 对肺功能正常患者实施小潮气量的保护性肺通气,PEEP在0和5 cmH2O2水平,对血流动力学无明显影响;当PEEP在10和15 cmH2O冰平时ACI增强和TFC减少,有潜在血流动力学危害;当PEEP在20 cmH2O时CI和MAP均降低.有明显血流动力学波动.     

高渗氯化钠对单肺通气时呼吸力学的影响

目的 探讨高渗氯化钠对单肺通气患者呼吸力学参数的影响.方法 选择拟单肺通气剖胸手术患者60例,随机均分为高渗氯化钠治疗组(H组)和对照组(C组).在单肺通气30 min后经中心静脉导管输注7.5％氯化钠溶液(H组)或生理盐水(C组)2 ml/kg.观察单肺通气前(T1)、单肺通气后30 min(T2)、输注后30 min(T3)、60 min(T4)、单肺通气结束时(T5)的动态肺顺应性(Cdyn)、气道峰压(Ppeak)、气道平均压(Pmean)、动脉血氧分压(PaO2)、血清Na+浓度.结果 与T1时比较,两组患者T2时的Cdyn、PaO2明显降低,Ppeak、Pmean明显升高(P＜0.05).与T2时比较,T3～Ts时H组Cdyn、PaO2逐渐升高,Ppeak、Pmean逐渐下降(P＜0.05),且Cdyn、PaO2明显高于C组,Ppeak明显低于C组(P＜0.05).T4、T5时H组Pmean明显低于C组(P＜0.05).结论 7.5％氯化钠溶液对单肺通气患者的各呼吸力学参数有改善作用,对肺通气功能具有保护作用.     

全麻诱导期呼气末正压通气对老年患者无通气期的影响

目的 观察全麻诱导呼气末正压通气(PEEP)能否延长老年患者无通气期.方法 选择ASA Ⅰ～Ⅱ级、年龄大于65岁全麻老年患者30例,随机分为PEEP组和对照组(C组),每组15例.所有患者自主呼吸存在时行面罩吸100%O2 5 min.全麻诱导后,C组行控制呼吸(FiO2 100%,RR 12次/分,VT 10 ml/kg)5 min,PEEP组应用C组相同的控制呼吸条件加PEEP 6 cmH2O 5 min.无通气期为SpO2降至90%.记录无通气期时间,分别于入室后(T1)、面罩吸100%O2 5 min时(T2)、控制呼吸5 min时(T3)和SpO2降至90%时(T4)抽血样本行血气分析.结果 PEEP组无通气期时间为(396±121)s,显著长于C组(305±107)s(P＜0.05).动脉血气分析显示,两组患者T1、T2和T4时的PaO2和PaCO2相似,但T3时PEEP组的PaO2明显高于C组(P＜0.05),而PaCO2显著低于C组(P＜0.05).结论 全麻诱导应用PEEP,可增加氧储备,延长老年患者无通气期.     

Comparison between conventional and protective one-lung ventilation for ventilator-assisted thoracic surgery

Recent papers suggest protective ventilation (PV) as a primary ventilation strategy during one-lung ventilation (OLV) to reduce postoperative pulmonary morbidity. However, data regarding the advantage of the PV strategy in patients with normal preoperative pulmonary function are inconsistent, especially in the case of minimally invasive thoracic surgery. Therefore we compared conventional OLV (VT 10 ml/kg, FiO2 1.0, zero PEEP) to protective OLV (VT 6 ml/kg, FiO2 0.5, PEEP 5 cmH2O) in patients with normal preoperative pulmonary function tests undergoing video-assisted thoracic surgery. Oxygenation, respiratory mechanics, plasma interleukin-6 and malondialdehyde levels were measured at baseline, 15 and 60 minutes after OLV and 15 minutes after restoration of two-lung ventilation. PaO2 and PaO2/FiO2 were higher in conventional OLV than in protective OLV (P<0.001). Interleukin-6 and malondialdehyde increased over time in both groups (P<0.05); however, the magnitudes of increase were not different between the groups. Postoperatively there were no differences in the number of patients with PaO2/FiO2<300 mmHg or abnormalities on chest radiography. Protective ventilation did not provide advantages over conventional ventilation for video-assisted thoracic surgery in this group of patients with normal lung function.     

Positive end-expiratory pressure applied to the dependent lung during one-lung ventilation improves oxygenation and respiratory mechanics in patients with high FEV1

BACKGROUND AND OBJECTIVE: The aim of this study was to test the efficacy of positive end-expiratory pressure (PEEP) to the dependent lung during one-lung ventilation, taking into consideration underlying lung function in order to select responders to PEEP. METHODS: Forty-six patients undergoing open-chest thoracic surgical procedures were studied in an operating room of a university hospital. Patients were randomized to receive zero end-expiratory pressure (ZEEP) or 10 cmH2O of PEEP to the dependent lung during one-lung ventilation in lateral decubitus. The patients were stratified according to preoperative forced expiratory volume in 1 s (FEV1) as an indicator of lung function (below or above 72%). Oxygenation was measured in the supine position, in the lateral decubitus with an open chest, and after 20 min of ZEEP or PEEP. The respiratory system pressure-volume curve of the dependent hemithorax was measured in supine and open-chest lateral decubitus positions with a super-syringe. RESULTS: Application of 10 cmH2O of PEEP resulted in a significant increase in PaO2 (P < 0.05). This did not occur in ZEEP group, considered as a time matched control. PEEP improved oxygenation only in patients with high FEV1 (from 11.6+/-4.8 to 15.3+/-7.1 kPa, P < 0.05). There was no significant change in the low FEV1 group. Dependent hemithorax compliance decreased in lateral decubitus, more in patients with high FEV1 (P < 0.05). PEEP improved compliance to a greater extent in patients with high FEV1 (from 33.6+/-3.6 to 48.4+/-3.9 mLcmH2O(-1), P < 0.05). CONCLUSIONS: During one-lung ventilation in lateral decubitus, PEEP applied to the dependent lung significantly improves oxygenation and respiratory mechanics in patients with rather normal lungs as assessed by high FEV1.     

支气管封堵器单肺通气在新生儿电视胸腔镜手术中的应用

目的探讨支气管封堵器（bronchial blocker,BB）行单肺通气（one lung ventilation,OLV）在新生儿电视胸腔镜手术（video-assisted thoracoscopicsugery,VATS）中应用的有效性和安全性。方法择期行VATS的患儿60例,按OLV方法完全随机平均分为支气管插管组（A组）和BB组（B组）,每组30例。比较两组患儿术前双肺通气时（T0）、OLV 10min（T1）、肺萎陷即刻（T2）、肺萎陷后30min（T3）、肺萎陷后60min（T4）、恢复双肺通气后10min（T5）和术毕6h（T6）、术毕12h（T7）的SpO2、动脉血氧分压（arterial blood partial pressure of oxygen, PaO2）、PET CO2、动脉血二氧化碳分压（arterial blood partial pressure of carbondioxide, PaCO2）、乳酸水平及气道压变化情况,比较两组患儿OLV情况和围术期情况。结果两组息儿气道压从T1开始升高,T4达到最高,T4时A组（34．8±4．9）cmH2O（1cmH2O=0．098kPa）较B组（30．0±4．3）cmH2O更为显著（P〈0．05）;T4时两组患儿SpO2和PaO2下降至最低,两组间比较差异无统计学意义（p〉0．05）;T4时两组患儿PETCO2和PaCO2升至最高,A组较B组更为显著（P〈0．05）;两组患儿乳酸水平呈升高趋势,但各时点差异无统计学意义（P〉0．05）。B组肺萎陷效果、术中出血量、手术时间、拔管时间、监护室时间和气管黏膜损伤情况均显著优于A组（P〈0．05）。结论BB行OLV可为新生儿VATS提供充分的通气和良好的肺萎陷。     

The effect of timing of application of positive end-expiratory pressure on oxygenation during one-lung ventilation

Many studies have confirmed that applying positive end-expiratory pressure (PEEP) to the dependent lung during one-lung ventilation (OLV) improves oxygenation. Our purpose was to investigate the best time and level of PEEP application. Thirty patients undergoing thoracic surgery were randomised into three groups. After 20 minutes of two-lung ventilation (TLV) in the lateral position, all patients received OLV for one hour During OLV, 0, 5, 10 cmH2O PEEP were applied in order in group A, with each level sustained for 20 minutes. Group B had 5 cmH2O PEEP applied and maintained for one hour Patients in group C received PEEP with levels set in the opposite order to that of group A. The ventilation model was then converted to TLV. PaO2, PaCO2 and respiratory mechanical variables were compared at five different time points among groups, 20 minutes after TLV (T1), 20 (T2), 40 (T3) and 60 minutes (T4) after OLV and 20 minutes after conversion to TLV (T5). We found that PaO2 was lower in group A than the other two groups at T2 (P <0.05). PaO2 decreased significantly at T5 compared with T1 (P <0.05) in group A only. When PEEP was set to 10 cmH2O, the airway pressure increased significantly (P <0.05). These findings indicate that PEEP applied at the initial time of OLV improves oxygenation most beneficially. Five cmH2O PEEP may produce this beneficial effect without the increase in airway pressure associated with 10 cmH2O PEEP.     

Evaluation of a recruitment maneuver with positive inspiratory pressure and high PEEP in patients with severe ARDS

BACKGROUND: To evaluate the effect of a recruitment maneuver (RM) with constant positive inspiratory pressure and high positive end-expiratory pressure (PEEP) on oxygenation and static compliance (Cs) in patients with severe acute respiratory distress syndrome (ARDS). METHODS: Eight patients with ARDS ventilated with lung-protective strategy and an arterial partial pressure of oxygen to inspired oxygen fraction ratio (PaO2/FIO2) < or =100 mmHg regardless of PEEP were prospectively studied. The RM was performed in pressure-controlled ventilation at FIO2 of 1.0 until PaO2 reached 250 mmHg or a maximal plateau pressure/PEEP of 60/45 cmH2O was achieved. The RM was performed with stepwise increases of 5 cmH2O of PEEP every 2 min and thereafter with stepwise decreases of 2 cmH2O of PEEP every 2 min until a drop in PaO2 >10% below the recruitment PEEP level. Data was collected before (preRM), during and after 30 min (posRM). RESULTS: The PaO2/FIO2 increased from 83 +/- 22 mmHg preRM to 118 +/- 32 mmHg posRM (P = 0.001). The Cs increased from 28 +/- 10 ml cmH2O(-1) preRM to 35 +/- 12 ml cmH2O(-1) posRM (P = 0.025). The PEEP was 12 +/- 3 cmH2O preRM and was set at 15 +/- 4 cmH2O posRM (P = 0.025). The PEEP of recruitment was 36 +/- 9 cmH2O and the collapsing PEEP was 13 +/- 4 cmH2O. The PaO2 of recruitment was 225 +/- 105 mmHg, with five patients reaching a PaO2 > or = 250 mmHg. The FIO2 decreased from 0.76 +/- 0.16 preRM to 0.63 +/- 0.15 posRM (P = 0.001). No major complications were detected. CONCLUSION: Recruitment maneuver was safe and useful to improve oxygenation and Cs in patients with severe ARDS ventilated with lung-protective strategy.     

Immediate effects of positive end-expiratory pressure and low and high tidal volume ventilation upon gas exchange and compliance in patients with acute lung injury.

BACKGROUND: Protective ventilation, in general, includes low tidal volume ventilation and maintaining end-inspiratory plateau pressures less than 35 cmH2O. Recent clinical studies have determined that such an approach results in improved survival in patients with moderate to severe acute lung injury and acute respiratory distress syndrome. However, experimental evidence suggests that repeated end-expiratory collapse and reexpansion contributes to ventilator-induced lung injury. We sought to determine the immediate effects of specific tidal volume-PEEP combinations upon oxygenation and static compliance in patients with moderate to severe acute lung injury. METHODS: Fourteen patients were prospectively studied and were treated with each of 10 tidal volume-PEEP combinations, applied in random order. After 5 minutes at each tidal volume-PEEP combination, PaO2/FIO2 and static compliance were recorded. Comparisons were made between low and high tidal volume ventilation as well as across five PEEP levels. RESULTS: At both low (6 mL/kg) and high (10 mL/kg) tidal volume ventilation, PaO2/FIO2 increased with increasing PEEP, up to 20 cmH2O. Similar changes in static compliance were not evident. Static compliance was highest at PEEP of 10 and 15 cmH2O, regardless of tidal volume. With PEEP set at 5 cmH2O, static compliance was significantly lower with 6 mL/kg than with 10 mL/kg tidal volumes. Overall, static compliance was lowest for both tidal volume conditions with PEEP set at 25 cmH2O. CONCLUSION: Low tidal volume ventilation with PEEP set at 5 cmH2O results in poor oxygenation and compliance in patients with moderate to severe acute lung injury. Similarly, PEEP set at 25 cmH2O did not improve oxygenation or compliance.     

左布比卡因复合右美托咪定在分娩镇痛中的应用及对母儿的影响

目的 研究左布比卡因复合右美托咪定(dexmedetomidine,Dex)在分娩镇痛中的应用及对母儿的影响. 方法 120例单胎、头位、初产妇,采用随机数字表法分为两组(每组60例),观察组(A组)应用左布比卡因复合Dex,对照组(B组)应用左布比卡因复合舒芬太尼,两组均采用硬膜外麻醉方式.产妇行硬膜外穿刺,两组分别给予0.1％左布比卡因+0.5 mg/L Dex复合液和0.1％左布比卡因+0.5 mg/L舒芬太尼复合液各5 ml.连接泵镇痛,泵速设置为8ml/h,患者自控镇痛(patient controlled analgesia,PCA)追加5 ml/次,锁定15 min.观察两组产妇生命体征、VAS评分、Bromage评分、Ramsay评分、产程、产后出血及新生儿Apgar评分. 结果 与麻醉前(T0)比较,麻醉后30 min(Tt)两组产妇MAP[A组,(81.8±4.7) mmHg(1 mmHg=0.133 kPa)比(93.0±6.2) mmHg;B组,(86.3±5.4)mmHg比(93.8±7.0) mmHg]、HR[A组,(70±10)次/min比(90±10)次/min;B组,(76±8)次/min比(88±8)次/min]均降低(P＜0.05).VAS评分,在T0、T1、活跃期1 h(T2)、第二产程1 h(T3)时,A组分别为(8.6±1.1)、(1.3±0.7)、(1.7±0.6)、(3.5±0.7)分,B组分别为(8.8±1.2)、(3.0±0.3)、(3.0±0.5)、(3.2±0.8)分,两组差异有统计学意义(P＜0.05).Ramsay评分在T1～T3时点,B组[(3.0±0.2)、(4.0±0.3)、(4.0±0.1)分]与A组[(2.0±0.3)、(2.0±0.2)、(2.0±0.1)分]比较,差异有统计学意义(P＜0.05).两组Bromage评分、产程时间、妊娠结局、产后出血及新生儿Apgar评分比较,差异无统计学意义(P＞0.05). 结论 左布比卡因复合Dex用于分娩镇痛安全、有效、舒适.     

Relation of the Static Compliance Curve and Positive End-expiratory Pressure to Oxygenation during One-lung Ventilation

Background : Positive end-expiratory pressure (PEEP) is commonly applied to the ventilated lung to try to improve oxygenation during one-lung ventilation but is an unreliable therapy and occasionally causes arterial oxygen partial pressure (Pao2) to decrease further. The current study examined whether the effects of PEEP on oxygenation depend on the static compliance curve of the lung to which it is applied.

Methods : Forty-two adults undergoing thoracic surgery were studied during stable, open-chest, one-lung ventilation. Arterial blood gasses were measured during two-lung ventilation and one-lung ventilation before, during, and after the application of 5 cm H2O PEEP to the ventilated lung. The plateau end-expiratory pressure and static compliance curve of the ventilated lung were measured with and without applied PEEP, and the lower inflection point was determined from the compliance curve.

Results : Mean (+/- SD) Pao2 values, with a fraction of inspired oxygen of 1.0, were not different during one-lung ventilation before (192 +/- 91 mmHg), during (190 +/- 90), or after ( 205 +/- 79) the addition of 5 cm H2O PEEP. The mean plateau end-expiratory pressure increased from 4.2 to 6.8 cm H2O with the application of 5 cm H2O PEEP and decreased to 4.5 cm H2O when 5 cm H2O PEEP was removed. Six patients showed a clinically useful (> 20%) increase in Pao2 with 5 cm H2O PEEP, and nine patients had a greater than 20% decrease in Pao2. The change in Pao2 with the application of 5 cm H2O PEEP correlated in an inverse fashion with the change in the gradient between the end-expiratory pressure and the pressure at the lower inflection point (r = 0.76). The subgroup of patients with a Pao2 during two-lung ventilation that was less than the mean (365 mmHg) and an end-expiratory pressure during one-lung ventilation without applied PEEP less than the mean were more likely to have an increase in Pao2 when 5 cm H2O PEEP was applied.