Effects of PEEP on oxygenation and respiratory mechanics during one-lung ventilation

Background. One-lung ventilation-related hypoxaemia (OLV-RH)can occur in patients with healthy lungs. In this case, PEEPfrequently improves oxygenation. The aim of this study was todetermine, in a healthy lung model of OLV, whether the increasein PEEP improved oxygenation and whether the mechanisms involvedinclude both inspiratory lung recruitment and an end-expiratorylung volume increase. Since inhaled nitric oxide (iNO) may havea synergistic effect on oxygenation in the case of PEEP-inducedrecruitment, their association was also tested. Methods. Twenty pigs were studied during open-chest, left OLV.Arterial blood gases and haemodynamic variables were measuredat different levels of PEEP (0, 5, 10 and 15 cm H₂O) appliedin random order with or without iNO 4 p.p.m. Pressure–volumecurves were measured at each level of PEEP. Results. PEEP₅ and PEEP₁₀ improved / ratio (P<0.005) and shunt (P<0.005) regardlessof the presence of iNO. PEEP₁₅ improved oxygenation and shuntonly when it was associated with iNO (P<0.001). Whereas PEEP₅,PEEP₁₀ and PEEP₁₅ were associated with a significant increasein end-expiratory volume (P<0.001), only PEEP₅ and PEEP₁₀were associated with continuous lung volume recruitment (P<0.01).Moreover, PEEP₁₅ induced a significant decrease in linear compliance(P<0.001). Conclusions. In a healthy porcine lung model of OLV-RH, moderatePEEP can improve oxygenation. This effect implies both expiratoryand inspiratory pulmonary recruitment. Co-administration of4 p.p.m. iNO was ineffective.     

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。     

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。     

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.     

Effect of low tidal volume with PEEP on respiratory function in infants undergoing one-lung ventilation

Die Anaesthesiologie - An increasing number of studies have shown that low tidal volume (TV) with positive end-expiratory pressure (PEEP) offers lung protection during one-lung ventilation (OLV)....     

Epidural block does not worsen oxygenation during one-lung ventilation for lung resections under isoflurane/nitrous oxide anaesthesia

BACKGROUND AND OBJECTIVES: The aim of this prospective, randomized, controlled clinical study was to evaluate the effects of thoracic epidural anaesthesia combined with isoflurane/nitrous oxide anaesthesia on intraoperative oxygenation during one-lung ventilation for lung resections. METHODS: Forty patients were randomly allocated to receive general anaesthesia maintained with isoflurane/nitrous oxide (group General, n = 20) or the same anaesthetic combined with thoracic epidural anaesthesia (group Integrated, n = 20). All patients were mechanically ventilated with the same settings (FiO2 = 0.5; VT = 9 mL kg(-1); inspiratory: expiratory time = 1:1; inspiratory pause = 10%). Effects on oxygenation were evaluated by determining the changes in PaO2/FiO2 ratio at 10, 30, 45 and 60 min of one-lung ventilation as compared to values obtained after induction of anaesthesia (supine, two-lung ventilation). RESULTS: The PaO2/FiO2 ratio was decreased in both groups during one-lung ventilation until the end of surgery. No differences were found at any observation time between the groups. Ventilation with 100% oxygen because of SpO2 decrease <92% was required in nine patients of group General (45%) and in eight patients of group Integrated (40%) (P = 0.64). Manual re-inflation of the operated lung was required in one patient of group General only (P = 0.99). Heart rate was lower in group Integrated than in group General throughout the study. No differences between the two groups in mean arterial pressure were observed. CONCLUSIONS: Adding a thoracic epidural block to isoflurane/nitrous oxide anaesthesia during one-lung ventilation for lung resections does not result in clinically relevant detrimental effects on intraoperative oxygenation.     

Effects of thoracic epidural anaesthesia on pulmonary venous admixture and oxygenation during one-lung ventilation

BACKGROUND: In this clinical randomized study, the effects of four anaesthesia techniques during one-lung ventilation [total intravenous anesthesia (TIVA) with or without thoracic epidural anaesthesia (TEA) (G-TIVA-TEA and G-TIVA), isoflurane anaesthesia with or without TEA (G-ISO-TEA and G-ISO)] on pulmonary venous admixture (Qs/Qt) and oxygenation (OLV) were investigated. METHODS: In 100 patients (four groups, 25 patients in each) undergoing thoracotomy, a thoracic epidural catheter was inserted pre-operatively. In G-TIVA-TEA and G-ISO-TEA, bupivacaine 0.1% + 0.1 mg/ml morphine was administered intra-operatively (10 ml of first bolus + 7 ml/h infusion). Propofol infusion or isoflurane concentration was adjusted to keep a bispectral index (BIS) of between 40 and 50 in all groups. FiO(2) was 0.8 during OLV and 0.5 before and after OLV. Partial arterial and central venous oxygen pressures (PaO(2) and PvO(2)), arterial and venous oxygen saturations and Qs/Qt values were recorded before, during and after OLV. RESULTS: During OLV, PaO(2) was significantly higher and Qs/QT significantly lower in G-TIVA-TEA and G-TIVA compared with G-ISO-TEA and G-ISO (PaO2: 188 +/- 36; 201 +/- 39; 159 +/- 33; 173 +/- 42 mmHg, respectively; Qs/Qt: 31.2 +/- 7.4; 28.2 +/- 7; 36.7 +/- 7.1; 33.7 +/- 7.7%, respectively). No statistical changes were observed in patients with TEA compared with without TEA in any measurement. CONCLUSION: During OLV, TEA does not significantly affect the oxygenation and Qs/Qt and can be used safely regardless of whether TIVA or inhalation techniques are used.     

氟比洛芬酯对胸腔镜右肺叶切除术患者单肺通气期间肺功能的影响

目的： 观察氟比洛芬酯对胸腔镜右肺叶切除术患者采用封堵器行单肺通气期间肺氧合功能、呼吸力学及肺部并发症的影响。
方法： 选择择期全麻下行胸腔镜右肺叶切除术采用封堵器行单肺通气的患者60例,男25例,女35例,年龄35～64岁,BMI 18～28 kg/m²,ASA Ⅰ或Ⅱ级。采用随机数字表法将患者分为两组：氟比洛芬酯组（F组）和对照组（C组）,每组30例。F组在麻醉诱导前15 min静注氟比洛芬酯1.0 mg/kg,C组不予处理。于麻醉诱导前20 min（T₀）、单肺通气30 min（T₁）、单肺通气60 min（T₂）、双肺通气15 min（T₃）时抽取桡动脉血行血气分析,计算氧合指数（OI）并记录SpO₂。记录T₁、T₂时的气道峰压（Ppeak）、气道平台压（Pplat）、肺动态顺应性（Cdyn）和无效腔气量与潮气量之比（V_D/V_T）。记录单肺通气期间低氧血症发生情况、补救例数、术后转ICU例数、术后72 h内肺不张、急性肺损伤和肺炎发生情况。
结果： 与C组比较,F组T₁时SpO₂、T₁—T₃时PaO₂和OI、T₁、T₂时Cdyn明显升高（P<0.05）;T₁、T₂时Ppeak和V_D/V_T、T₂时Pplat明显降低（P<0.05）。两组无一例单肺通气期间发生低氧血症和补救、术后转入ICU、术后72 h内发生肺不张、急性肺损伤和肺炎。
结论： 对胸腔镜右肺叶切除术采用封堵器行单肺通气的患者,麻醉诱导前静注氟比洛芬酯有助于改善单肺通气期间肺氧合功能,优化呼吸力学参数。     

The effects of intravenous almitrine on oxygenation and hemodynamics during one-lung ventilation

One-lung ventilation (OLV) induces an increase in pulmonary shunt sometimes associated with a decrease in PaO2 despite ventilation with 100% oxygen. PaO2 improvement has been reported in one-lung ventilated animals receiving IV almitrine, a pulmonary vasoconstrictor. We evaluated the ability of almitrine to prevent a decrease in PaO2 during OLV. Patients without pulmonary hypertension undergoing OLV for lung surgery were randomly assigned to receive either placebo (Group P, n = 8) or almitrine infusion at a rate of 8 microg x kg(-1) x min(-1) (Group A, n = 8) from the start of OLV. Gasometric and hemodynamic values were recorded with the patient in the lateral decubitus position during two-lung ventilation and at 10-min intervals during OLV over a 30-min period (OLV-10, OLV-20, OLV-30). Compared with the values found during two-lung ventilation (434 +/- 22 mm Hg in Group P and 426 +/- 23 mm Hg in Group A), PaO2 decreased at OLV-10 (305 +/- 46 mm Hg), OLV-20 (203 +/- 20 mm Hg), and OLV-30 (178 +/- 18 mm Hg) in Group P (P < 0.05) and at OLV-20 (354 +/- 25 mm Hg) and OLV-30 (325 +/- 17 mm Hg) in Group A (P < 0.05). PaO2 values differed between the groups at OLV-20 and OLV-30 (P < 0.05). Pulmonary artery pressure and cardiac output did not change. In conclusion, 8 microg x kg(-1) x min(-1) IV almitrine prevents and limits the OLV-induced decrease in PaO2 without causing any hemodynamic modification. IMPLICATIONS: Eight microg x kg(-1) x min(-1) IV almitrine limits one-lung ventilation-induced decrease in PaO2 without causing any hemodynamic modification in patients without pulmonary hypertension.     

小潮气量联合呼气末正压对单肺通气肺内分流及炎性反应的影响

目的研究单肺通气（OLV）时小潮气量联合呼气末正压（PEEP）对肺内分流及炎性反应的影响。方法食管癌根治术患者60例,年龄20～65岁,随机均分为三组,OLV时患者V_T均为6ml/kg,PEEP分别为0cmH₂O（A组）、5cmH₂O（B组）和10cmH₂O（C组）。记录患者气道压变化,采集桡动脉血和深静脉血行血气分析并计算氧合指数（OI）和肺内分流率（Qs/Qt）,采集外周静脉血进行炎性因子检测。结果与双肺通气30min时比较,三组OLV30、60、90min时Qs/Qt、肿瘤坏死因子α（TNF-α）、T₂、T₃时A、C组白细胞介素-8（IL-8）明显增高（P<0.05）,但B组Qs/Qt、IL-8显著低于A、C组（P<0.05）。A、C组OLV30、60、90min时OI较双肺通气30min时明显降低（P<0.05）;B组仅在OLV30min时降低（P<0.05）。与A、C组比较,B组OLV30、60、90min时IL-10显著增高（P<0.05）。结论 OLV中V_T6ml/kg联合PEEP5cmH₂O可以降低Qs/Qt,减轻炎性反应,改善氧合。     

Progressive changes in arterial oxygenation during one-lung anaesthesia are related to the response to compression of the non-dependent lung

Background. Arterial oxygenation can change during one-lungventilation for reasons that are not fully understood. Methods. We studied patients during anaesthesia and one-lungventilation, with an inspiratory oxygen fraction of 0.8. Arterialblood gas values were recorded every 10 s with a continuousintra-arterial sensor. The non-dependent lung was compressedseveral times during the surgical procedure, using a retractor.The change in Pa_O2 during and after compression of the non-dependentlung was measured. Results. Pa_O2 increased significantly when the non-dependentlung was compressed, and decreased when the compression wasreleased. The first compression of the non-dependent lung transientlyincreased Pa_O2, but the effect of the second compression onoxygenation was more marked and persistent. Pa_O2 increased bymore than 13 kPa at 10 min after the second compression in fourpatients (responder group). Arterial oxygenation improved markedlyin patients in this group during the surgical procedure. Conclusion. Oxygenation can improve during one-lung ventilationin some patients. This improvement is partly related to a markedincrease in Pa_O2 during compression of the non-dependent lung. Br J Anaesth 2003; 90: 21–6     

Speed of collapse of the non-ventilated lung during one-lung anaesthesia: the effects of the use of nitrous oxide in sheep

By enhancing gaseous uptake from the non-ventilated lung during procedures performed thoracoscopically, the rapid diffusion properties of nitrous oxide would be expected to speed lung collapse and so facilitate surgery. To assess the effect of nitrous oxide on the speed of absorptive lung collapse, a study was conducted using 11 anaesthetised sheep. Speed of collapse was assessed in an indirect manner by recording the time required in a closed-chest situation for the airway pressure distal to a single lung airway occlusion to decrease to - 1.0 kPa. The influence of nitrous oxide was assessed by comparing the time taken for this decrease in airway pressure when the animal was being mechanically ventilated with 50% nitrous oxide in oxygen with the time taken when using 100% oxygen. In all assessments, it was found that the decrease in airway pressure to - 1.0 kPa occurred in a shorter time when nitrous oxide was used. The findings lend support to the hypothesis that during thoracoscopic surgery, mechanical lung ventilation with an oxygen/nitrous oxide mixture will increase the rate of gaseous uptake from the non-ventilated lung and so hasten its absorptive collapse.     

A comparison of the effects of desflurane and isoflurane on arterial oxygenation during one-lung ventilation

In a randomised prospective cross-over study, we compared the effects of desflurane and isoflurane on arterial oxygenation, heart rate and mean arterial pressure during one-lung anaesthesia. Thirty patients scheduled for oesophagogastrectomy were randomly assigned to one of two groups. One group of 15 patients received desflurane to an end-tidal concentration of 6% in oxygen from induction until the end of 30 min of open chest one-lung ventilation in the lateral position. This was followed by isoflurane to an end-tidal concentration of 1.1% in oxygen for the next 30 min of one-lung ventilation. The other group of 15 patients received the two anaesthetic agents in the reverse order. We found no significant difference in arterial oxygenation, heart rate or mean arterial pressure between the two inhalational agents. In the subgroup of 10 patients with pulmonary artery catheters, we found no significant differences in mixed venous saturation, derived shunt or cardiac output. We conclude that during one-lung ventilation, the choice between desflurane and isoflurane does not significantly influence arterial oxygenation.     

小潮气量联合PEEP对单肺通气时胸外科手术患者血管外肺水的影响

目的 探讨小潮气量联合呼气末正压(PEEP)对单肺通气时胸外科手术患者血管外肺水的影响.方法 食道癌手术患者40例,年龄45～80岁,体重48～83kg,性别不限,ASA分级Ⅰ或Ⅱ级,随机分为2组(n=20):传统模式单肺通气组(Ⅰ组)机械通气模式为间歇正压通气(IPPV),VT9 ml/kg,通气频率12次/min;小潮气量联合PEEP单肺通气组(Ⅱ组)机械通气模式为IPPV联合PEEP5 cm H2O,VT6 ml/kg,通气频率15次/min.于麻醉诱导前(T0)、双肺通气30 min(T1)、单肺通气30 min(T2)、单肺通气1 h(T3)、恢复双肺通气拔管前(T4)和术后18 h(T5)时,记录血管外肺水(EVLW)、血管外肺水指数(EVLWI)、肺血管通透性指数(PVPI)和心输出量(CO),于T1～4时记录气道峰压(Ppeak);取股动脉血样,进行血气分析,并计算氧合指数(OI).结果 与Ⅰ组比较,Ⅱ组单肺通气期间EVLWI和.PVPI升高(P＜0.05),其余指标比较差异无统计学意义(P＞0.05);两组各时点OI、CO和Poeak比较差异无统计学意义(P＞0.05);与T0时比较,Ⅰ组T1时PVPI升高(P＜0.05),其余时点PVPI、EVLW和EVLWI差异无统计学意义(P＞0.05),Ⅱ组T2时EVLW、T1～4时EVLWI和T1.2时PVPI升高(P＜0.05);与T1时比较,Ⅰ组T2～5时EVLW、EVLWI和PVPI差异无统计学意义,Ⅱ组T5时PVPI降低(P＜0.05).结论 采用VT6 ml/kg、PEEP 5 cm H2O的单肺通气可增加患者血管外肺水,未对肺功能产生有利作用.     

Comparison of two protective lung ventilatory regimes on oxygenation during one-lung ventilation: a randomized controlled trial

Background  

The efficacy of protective ventilation in acute lung injury has validated its use in the operating room for patients undergoing thoracic surgery with one-lung ventilation (OLV). The purpose of this study was to investigate the effects of two different modes of ventilation using low tidal volumes: pressure controlled ventilation (PCV) vs. volume controlled ventilation (VCV) on oxygenation and airway pressures during OLV.     

Maintenance of oxygenation during one-lung ventilation. Effect of intermittent reinflation of the collapsed lung with oxygen

The aim of this study was to evaluate the effect on oxygenation of intermittent inflation with oxygen of the collapsed lung during one-lung ventilation (OLV). Sixteen patients were studied during pulmonary surgery. Balanced anesthesia with nitrous oxide and an inspired oxygen fraction of 0.5 was used. The control group (N = 8) had a median PaO2 of 19.2 (range 11.2-30.2) kPa before OLV, and 10.2 (8.2-16.0) kPa after 9 minutes of OLV without further reduction in PaO2 for another 10 minutes. In the treatment (inflation) group, the collapsed lung was manually inflated with 2 liters of oxygen and was then immediately allowed to collapse again. This procedure was repeated every 5 minutes during OLV. PaO2 increased more than 4 kPa following each inflation in seven patients. In the eighth, PaO2 remained high throughout OLV. Although PaO2 decreased between inflations, it never reached the level observed in controls during 19 minutes of OLV.