胸科手术的单肺通气策略

背景 在胸科手术的麻醉中进行单肺通气(one-lung ventilation,OLV),不但可以为手术提供良好的术野,而且可以隔离并保护肺脏.但是,这是一种非生理状态下的通气方式,OLV期间的气压伤和氧毒性等因素常导致机械通气相关性肺损伤(ventilator-induced lung injury,VILI). 目的 探讨适合胸科手术的OLV策略. 内容 在OLV期间,采用肺泡复苏策略(alveolar recruitment strategy,ARS)和“小潮气量+呼气末正压通气(positive end-expiratory pressure,PEEP)”的保护性通气策略,使吸气平台压(plateau pressure,Pplat)＜25 cmH2O(1 cmH2O=0.098 kPa)和气道峰压(peak inspiratory pressure,Ppeak)＜35 cmH2O;限制FiO2;依据动脉血气分析的结果,酌情调整呼吸频率. 趋向 在OLV期间,应避免肺泡的过度膨胀和循环性的萎陷-复张,避免高浓度氧导致氧化应激加重,可以接受短时间内的高碳酸血症.对患者进行个体化管理,降低ICU的入住率及住院时间,提高患者的生存率及生存质量.     

单肺通气时机械通气模式的研究进展

背景 单肺通气(one lung ventilation,OLV)实施过程中最常见的并发症是低氧血症,也是麻醉医师遇到的最严重的挑战. 目的 近来研究表明OLV本身能够引起低氧血症和急性肺损伤(acute lung injury,ALI).因此,如何实施OLV时机械通气模式,降低肺内分流率(pulmonary shunt fraction,Qs/Qt)、预防低氧血症一直是临床研究的热点. 内容 综述提高吸入氧分数(fraction of inspiration O2,FiO2)、控制通气模式、高频通气(high frequency ventilation,HFV)、潮气量(tidal volume,Vt)、反比通气、部分液体通气(partial liquid ventilation,PLV)、持续气道正压通气(continuous positive airway pressure,CPAP)、呼气末正压通气(positive end-expiratory pressure,PEEP)等通气模式,以及实施联合多种模式的保护性肺通气策略. 趋向 综合运用多种预防OLV期间低氧血症的通气模式取得良好的效果,但应针对患者和手术情况制定OLV时机械通气模式.     

肺肿瘤切除术肥胖患者的围术期肺康复管理

目的提高肺肿瘤切除术肥胖患者的肺康复效果。方法将行肺肿瘤切除术肥胖患者按手术时间分为对照组32例,观察组37例。对照组按常规行呼吸道管理,观察组在对照组基础上加强围术期肺康复管理。结果观察组术后机械通气使用率及机械通气时间、肺部感染发生率、高碳酸血症发生率、术后住院时间显著低于对照组(P0.05,P0.01)。结论对肺肿瘤切除术肥胖患者加强围术期肺康复管理,有利于患者快速康复。     

成人呼吸窘迫综合征机械通气期间呼吸道的管理

目的:探讨成人呼吸窘迫综合征机械通气期间呼吸道的管理.方法:对36例ARDS患者机械通气治疗采用肺保护性通气策略,主要措施为应用呼气末正压(PEEP)使呼气末肺容量增加,萎陷的小气道和肺泡再开放,减轻肺泡水肿,增加功能残气量和肺顺应性,从而改善通气和氧合,减少肺内分流.小潮气量,防止肺泡过度充气,允许性高碳酸血症.做好呼吸道的管理.结果:成人呼吸窘迫综合征机械通气期间通过呼吸道的管理可明显提高机械通气的治疗效果.结论:成人呼吸窘迫综合征机械通气期间通过加强呼吸道的管理,降低身心刺激,促进病人康复.     

肺切除病人在单肺通气时的控制性高碳酸血症

开胸手术时,从双肺通气转换成单肺通气(one lungventilation;OLV),常增大下肺(通气肺)的气道压力。如果原先病人通气量就高,则在单肺通气时气压伤的危险就可能增大。近年的研究已证实,容许性高碳酸血症(容许性CO2血症;permissive hypercapnia简称PHC),可允许肺泡通气和通气压峰值都降低引起PaCO2升高,却能减轻肺损伤,提高     

单肺通气期间低氧血症的发生机制及防治策略

单肺通气（one-lung ventilation, OLV）是保障胸科手术顺利进行的关键技术。但OLV期间约有9%～27%的患者发生低氧血症,给手术顺利进行带来风险。低氧血症会增加患者在围术期发生认知功能障碍、房颤、肾衰竭和肺动脉高压等并发症的风险。因此,在进行OLV时低氧血症的预防和处理是术中麻醉管理的重要问题。本文就近年来OLV期间低氧血症的发生机制和防治策略的研究进展作一综述。     

单肺通气萎陷肺损伤机制的研究

背景 单肺通气(one lung ventilation,OLV)常用于胸科手术中,OLV不仅导致通气侧肺损伤,缺氧、低灌注状态也会导致萎陷侧肺出现严重的炎症反应,甚至造成远端器官的损伤,严重影响患者的预后及生存率. 目的 简要归纳总结OLV期间萎陷肺损伤可能的发生机制. 内容 OLV期间萎陷肺损伤可能的机制包括氧化应激反应、炎症反应、免疫反应、肺泡表面活性物质的减少及萎陷肺水肿. 趋向 通过探讨OLV萎陷肺损伤的机制为临床中预防和治疗OLV萎陷肺损伤提供理论依据.     

单肺通气期间麻醉期用药对肺内分流的影响

背景 低氧血症是单肺通气(one lung ventilation,OLV)期间最常见的并发症.缺氧性肺血管收缩(hypoxic pulmonary vasoconstriction,HPV)是肺血管对局部低氧分压的反射性收缩,可以减少肺内分流(pulmonary shunt fraction,Qs/Qt)、维持动脉血氧分压(partial pressure of arterial oxygen,PaO2)、防止低氧血症的发生.目的 探讨OLV期间麻醉期用药对Qs/Qt的影响,指导临床应用.内容 综述OLV期间麻醉期用药对机体HPV、Qs/Qt和PaO2的影响.趋向 OLV期间麻醉期用药可以对HPV产生抑制或增强作用,从而影响Qs/Qt和PaO2.临床上要避免使用抑制HPV作用、增加Qs/Qt的药物,防止患者出现低氧血症.     

肺保护性通气策略对腹腔镜手术患者顺式阿曲库铵作用时间的影响

有研究证实,高碳酸血症可能减弱非去极化肌松药的代谢,延长作用时间[1]。对于腹腔镜手术患者,建议用低潮气量、小的呼气末正压(positive end expiratory pressure,PEEP)联合使用间断肺复张的保护性通气策略,从而减少肺损伤和术后肺部并发症的发生[2-3]。肺保护性通气策略和二氧化碳气腹所致的允许性高碳酸血症,可能会影响顺式阿曲库铵的作用时间[4]。本研究观察在采用肺保护性通气策略的腹腔镜手术患者中顺式阿曲库铵的作用时间,为临床合理使用苄异喹啉类非去极化肌松药提供参考。     

肥胖患者围术期通气策略的研究进展

肥胖患者在手术人群中所占的比例逐年上升.肥胖不仅影响了患者的生理功能,也给麻醉和手术带来不少难题.现就此讨论肥胖患者围手术期的呼吸管理,包括术前的呼吸治疗、术中的机械通气策略及术后的呼吸支持等问题.对肥胖患者围术期呼吸生理改变的了解,详尽的、个体化的通气设置和术中术后完善的通气管理有助于减少肥胖患者呼吸系统并发症的发生.     

Lung recruitment improves the efficiency of ventilation and gas exchange during one-lung ventilation anesthesia

Atelectasis in the dependent lung during one-lung ventilation (OLV) impairs arterial oxygenation and increases dead space. We studied the effect of an alveolar recruitment strategy (ARS) on gas exchange and lung efficiency during OLV by using the single-breath test of CO(2) (SBT-CO(2)). Twelve patients undergoing thoracic surgery were studied at three points in time: (a) during two-lung ventilation and (b) during OLV before and (c) after an ARS. The ARS was applied selectively to the dependent lung and consisted of an increase in peak inspiratory pressure up to 40 cm H(2)O combined with a peak end-expiratory pressure level of 20 cm H(2)O for 10 consecutive breaths. The ARS took approximately 3 min. Arterial blood gases, SBT-CO(2), and metabolic and hemodynamic variables were recorded at the end of each study period. Arterial oxygenation and dead space were better during two-lung ventilation compared with OLV. PaO(2) increased during OLV after lung recruitment (244 +/- 89 mm Hg) when compared with OLV without recruitment (144 +/- 73 mm Hg; P < 0.001). The SBT-CO(2) analysis showed a significant decrease in dead-space variables and an increase in the variables related to the efficiency of ventilation during OLV after an ARS when compared with OLV alone. In conclusion, ARS improves gas exchange and ventilation efficiency during OLV. IMPLICATIONS: In this article, we showed how a pulmonary ventilatory maneuver performed in the dependent lung during one-lung ventilation anesthesia improved arterial oxygenation and dead space.     

Alveolar recruitment strategy increases arterial oxygenation during one-lung ventilation

BACKGROUND: Deterioration of gas exchange during one lung ventilation (OLV) is caused by both total collapse of the nondependent lung and partial collapse of the dependent lung. A previous report demonstrated that an alveolar recruitment strategy (ARS) improves lung function during general anesthesia in supine patients. The objective of this article was to study the impact of this ARS on arterial oxygenation in patients undergoing OLV for lobectomies. METHODS: Ten patients undergoing open lobectomies were studied at three time points: (1) during two-lung ventilation (TLV), (2) during OLV before, and (3) after ARS. The ARS maneuver was done by increasing peak inspiratory pressure to 40 cm H2O, together with a positive end-expiratory pressure (PEEP) of 20 cm H2O for 10 respiratory cycles. After the maneuver, ventilation parameters were returned to the settings before intervention. RESULTS: During OLV, PaO2 was statistically lower before the recruitment (data as median, first, and third quartile, 217 [range 134 to 325] mm Hg) compared with OLV afterwards (470 [range 396 to 525] mm Hg) and with TLV (515 [range 442 to 532] mm Hg). After ARS, PaO2 values during OLV were similar to those during TLV. During OLV, the degree of pulmonary collapse in the nondependent lung, the hemodynamic status, and the ventilation parameters were similar before and after ARS. CONCLUSIONS: Alveolar recruitment of the dependent lung augments PaO2 values during one-lung ventilation.     

Histochemical alterations in one lung ventilation

BACKGROUND: One lung ventilation is a commonly performed surgical procedure. Although there have been several reports showing that one-lung ventilation can cause pathophysiological alterations such as pulmonary hypoxic vasoconstriction and intrapulmonary shunting, there have been virtually no reports on the effects of one-lung ventilation on lung histology. MATERIALS AND METHODS: Yorkshire pigs (11-17 kg) were anesthetized, a tracheotomy performed and a tracheal tube inserted. The chest was opened and one lung ventilation (OLV), was induced by clamping of the right main bronchus. OLV was continued for 60 min before the clamp was removed and two lung ventilation (TLV) started. TLV was continued for 30 to 60 min. Blood and lung biopsies were taken immediately before OLV, 30 min and 60 min of OLV and after restoration of TLV. RESULTS: Histological analyses revealed that the non-ventilated lung was totally collapsed during OLV. On reventilation, there was clear evidence of vascular congestion and alveolar wall thickening at 30 min after TLV. At 60 min of TLV, there was still vascular congestion. Serum nitrite levels (as an index of nitric oxide production) showed steady decline over the course of the experimental period, reaching a significantly low level on reventilation (compared with baseline levels before OLV). Lung MPO activity (marker of neutrophil sequestration) and serum TNFalpha levels were not raised during the entire experimental period. CONCLUSIONS: These results suggest that there was lung vascular injury after OLV, which was associated with reduced levels of nitric oxide production and not associated with an inflammatory response.     

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.     

Ventilatory management of one-lung ventilation

Hypoxemia is considered to be the most important challenge during one-lung ventilation (OLV). Recent studies, however, have shown that one-lung ventilation can involve some lung damage and can therefore be per se a cause of hypoxemia. OLV can be associated to an injury: but the techniques used to improve oxygenation may also damage the lung. A new ventilator approach should be used and applied with regards to what is so far known in terms of "lung protection" also during OLV.     

Arterial oxygenation during one lung ventilation in obese patients

To test the hypothesis that arterial oxygenation during one lung ventilation (OLV) is impaired more in obese patients than in non-obese control patients, we performed consecutive measurements of arterial oxygen tension (PaO2) during OLV in 48 patients scheduled for pulmonary lobectomy. Minimum value of PaO2 during OLV was significantly less in 16 obese patients [body mass index (BMI) > 25] compared to 32 control patients (BMI < 25). Moreover, PaO2 value of left lung ventilation was significantly less than the value of right lung ventilation in obese patients while the difference was not statistically significant in the control group.     

The effects of remifentanil and thoracic epidural on oxygenation and pulmonary shunt fraction during one-lung ventilation

OBJECTIVE: To compare the effects of remifentanil and thoracic epidural analgesia on the hemodynamic changes and pulmonary shunt fraction during one-lung ventilation (OLV) for thoracotomy. DESIGN: Prospective, single crossover design. SETTING: Tertiary care hospital. PARTICIPANTS: Thirty-four patients undergoing OLV for thoracic surgery. INTERVENTIONS: During general anesthesia with 2-lung ventilation, one-lung ventilation with remifentanil infusion, and one-lung ventilation with thoracic epidural anesthesia (TEA), hemodynamic parameters and arterial and mixed venous blood gases were taken from the radial and pulmonary artery catheters. During these 3 study periods, cardiac index (CI) was measured using thermodilution technique while shunt fraction (Qs/Qt), alveolar arterial oxygen gradient (A-a O(2)), and systemic (SVRI) and pulmonary vascular resistances indices (PVRI) were calculated. A p value <0.05 was taken to be statistically significant. MEASUREMENTS AND MAIN RESULTS: When OLV was instituted, there was a significant decrease in mean arterial blood pressure. Arterial oxygenation decreased, whereas CI and Qs/Qt increased during OLV, but there was no significant difference between remifentanil infusion and thoracic epidural analgesia. CONCLUSIONS: Both remifentanil infusion and TEA are suitable for analgesia during thoracic surgery when OLV is used. There was no significant difference in PaO(2) and Qs/Qt during each administration.     

Respiration: ventilation

Anaesthetists and intensivists directly manipulate pulmonary function, in particular ventilation. A sound and thorough working knowledge of applied pulmonary physiology of ventilation is essential to the safe conduct of anaesthesia and intensive care medicine. This article discusses pulmonary anatomy, gas exchange in the lung, the mechanics of ventilation, airway resistance, elastance and compliance, the work of breathing and ventilation/perfusion relationships including hypoxic pulmonary vasoconstriction. General anaesthesia has profound effects on the respiratory system including the ventilatory response to hypercapnia and hypoxia, upper airway muscle function, lung volumes and ventilation/perfusion matching. Many surgical procedures are facilitated by one-lung ventilation. When utilizing one-lung ventilation a key aim for the anaesthetist is to maintain adequate alveolar ventilation while minimizing the amount of shunt through the non-ventilated lung. A detailed understanding of one-lung ventilation is therefore vital if a logical approach to management is to be adopted.     

One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure is injurious in the isolated rabbit lung model

We tested the hypothesis that one-lung ventilation (OLV) with high tidal volumes (VT) and zero positive end-expiratory pressure (PEEP) may lead to ventilator-induced lung injury. In an isolated, perfused rabbit lung model, VT and PEEP were set to avoid lung collapse and overdistension in both lungs, resulting in a straight pressure-time (P-vs-t) curve during constant flow. Animals were randomized to (a) nonprotective OLV (left lung) (n = 6), with VT values as high as before randomization and zero PEEP; (b) protective OLV (left lung) (n = 6), with 50% reduction of VT and maintenance of PEEP as before randomization; and (c) control group (n = 6), with ventilation of two lungs as before randomization. The nonprotective OLV was associated with significantly smaller degrees of collapse and overdistension in the ventilated lung (P < 0.001). Peak inspiratory pressure values were higher in the nonprotective OLV group (P < 0.001) and increased progressively throughout the observation period (P < 0.01). The mean pulmonary artery pressure and lung weight gain values, as well as the concentration of thromboxane B(2), were comparatively higher in the nonprotective OLV group (P < 0.05). A ventilatory strategy with VT values as high as those used in the clinical setting and zero PEEP leads to ventilator-induced lung injury in this model of OLV, but this can be minimized with VT and PEEP values set to avoid lung overdistension and collapse. IMPLICATIONS: One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure (PEEP) is injurious in the isolated rabbit lung model. A ventilatory strategy with tidal volumes and PEEP set to avoid lung overdistension and collapse minimizes lung injury during one-lung ventilation in this model.