Adaptive lung ventilation

Adaptive lung ventilation (ALV) is a method of closed-loop mechanical ventilation analogous to modern closed-loop technology in aviation such as the autopilot and automatic landing system. The algorithm of the controller of ALV is designed to automatically provide pressure-controlled synchronized intermittent mandatory ventilation (P-SIMV) and weaning as individually required in any clinical situation. The synchronized pressure limited breaths constantly adapt to the patient requirements to encourage optimal alveolar ventilation with minimal adverse physiological disturbance and timely weaning. The ease of application, efficiency, and safety of the first ALV controllers have been demonstrated in lung models, in patients with normal lungs undergoing general anesthesia, in patients requiring unusual positioning, in transition to and from one-lung anesthesia, and in long-term ventilation of patients with various lung pathologies and in weaning patients who have restrictive or obstructive pulmonary disease. Prospective comparative studies of ALV versus other currently used manually selected modes of mechanical ventilation, such as the one reported in this article, should confirm the safety and identify the benefits of this form of advanced closed-loop mechanical ventilation technology.     

Extrakorporale Lungenunterstützung beim hyperkapnischen Lungenversagen

In recent years the use of extracorporeal lung assist devices has rapidly increased in intensive care medicine. While venovenous extracorporeal membrane oxygenation (vv-ECMO) is applied as rescue therapy in patients with severe hypoxemic respiratory failure, extracorporeal CO₂ removal (ECCO₂R) can be applied in patients with hypercapnic respiratory failure. Especially in patients with acute on chronic hypercapnic respiratory failure treated with invasive mechanical ventilation, ventilator-associated side effects can lead to a poorer outcome. In these patients extracorporeal lung assist often enables lung protective ventilation and potentially ameliorates ventilator-associated side-effects. Moreover, by reducing the load on the respiratory muscle pump ECCO₂R may facilitate weaning from the ventilator and in individual patients with failure of non-invasive ventilation (NIV) may even help to avoid intubation. In selected patients with chronic lung disease listed for lung transplantation, the avoidance of invasive mechanical ventilation for acute decompensation by means of extracorporeal lung support may help to maintain the option for transplantation. The potential advantages of ECCO₂R must be weighed against the risks and complications.     

An Update on Interventional Lung Assist Devices and Their Role in Acute Respiratory Distress Syndrome

In recent years, pumpless arteriovenous systems for extracorporeal gas exchange have become a new therapeutic option for the treatment of patients suffering from acute respiratory failure. Experiences with the pumpless extracorporeal membrane lung in animal experiments and in patients with adult respiratory distress syndrome published in the current literature are reviewed. In addition this article presents a case of varicella pneumonia with persistent hypoxemia and hypercapnia under mechanical ventilation that showed a significant improvement with treatment with a pumpless extracorporeal lung assist using an arteriovenous shunt for eight days. The patient made a complete recovery. This is the first report of a patient with a life-threatening varicella pneumonia successfully treated with pumpless extracorporeal lung assist device. This review provides an update on interventional lung assist devices and a critical discussion of their advantages and limitations.     

Lysosomal enzyme activity influenced by various types of respiration during extracorporeal circulation

The hypoxic damage of the lung as seen after extracorporeal circulation (ECC) is in correlation to lysosomal hydrolase and protease activation. In the recent study the effect of various types of respiration during ECC on lysosomal enzyme release were studied. 53 patients undergoing open heart surgery were divided into 4 groups: Apnoea, low frequency, continuous positive airway pressure, combination of low frequency and continuous positive airway pressure. Paired blood samples were withdrawn from the superior vena cava (SVC) and the left atrium (LA) throughout the cardiopulmonary bypass. A continuous increase of N-azetyl-beta-D-Glucosaminidase (NAG) in venous plasma and significant differences (SVC-LA) with higher activities in the LA in the apnoea group were detectable (p less than or equal to 0.05-p less than or equal to 0.01). In the other groups a time dependent course could also be evaluated, but the changes of the activities were not significant. The different types of respiration during ECC influenced the clinical course and outcome of the patients in correlation to the release of lysosomal enzymes from the lung. It is concluded that concentration gradients of lysosomal enzymes are an index for pulmonary damage due to the extracorporeal perfusion in open heart surgery. The activation of lysosomal enzymes in the lung circulation are positively influenced by "ventilation" during ECC.     

Low‐flow veno‐venous extracorporeal carbon dioxide removal in the management of severe status asthmatics: a case report

Status asthmaticus is a life‐threatening condition that requires intensive care management. Most of these patients have severe hypercapnic acidosis that requires lung protective mechanical ventilation. A small proportion of these patients do not respond to conventional lung protective mechanical ventilation or pharmacotherapy. Such patients have an increased mortality and morbidity. Successful use of extracorporeal membrane oxygenation (ECMO) is reported in such patients. However, the use of ECMO is invasive with its associated morbidity and is limited to specialised centres. In this report, we report the use of a novel, minimally invasive, low‐flow extracorporeal carbon dioxide removal device in management of severe hypercapnic acidosis in a patient with life threatening status asthmaticus.     

Serum and plasma measurements of neutrophil granule proteins during cardiopulmonary bypass: a model to estimate human turnover of lactoferrin and myeloperoxidase

During extracorporeal circulation (ECC), granule proteins such as lactoferrin and myeloperoxidase escape to the plasma in large amounts. ECC was used to study the turnover of these proteins and compare their variations in plasma and serum. During ECC both proteins rose to very high levels and the variations were similar in both serum and plasma (r = 0.93 for lactoferrin and 0.80 for myeloperoxidase). The initial elimination after termination of operation (t 1/2) was, for lactoferrin 0.75 and for myeloperoxidase 0.5 h. Both proteins followed a second order kinetics of elimination with a t 1/2 for lactoferrin of about 9 and for myeloperoxidase of about 25 h. 48 and 72 h postoperatively serum levels, but not plasma levels, of myeloperoxidase rose again 10-fold. We conclude that serum and plasma measurements of neutrophil granule proteins are complementary. The period after disconnection of the patient from the extracorporeal device may be used to estimate the turnover kinetics of neutrophil granule proteins.     

Pumpless Extracorporeal Lung Assist for the Treatment of Severe,Refractory Status Asthmaticus

Background. Until recently, the only available lung-protective treatment option for carbon dioxide removal due to severe, refractory status asthmaticus has been extracorporeal pump-driven membrane oxygenation (ECMO). Pumpless extracorporeal lung assist (pECLA) may serve as an alternative therapy for these patients. Case Report. A 42-year-old woman presented with an acute exacerbation of asthma to our Emergency Department. Despite optimal pharmacological therapy, the patient developed respiratory failure requiring mechanical ventilation with elevated airway pressures. For severe ventilation-refractory hypercapnia and respiratory acidosis, ECMO was used initially and was later replaced by a pECLA device. The clinical condition continuously improved with sufficient pulmonary gas exchange. The pECLA was removed after 8 days, and the patient was successfully weaned from mechanical ventilation. Conclusions. This report suggests that pECLA is an alternative extracorporeal lung assist in patients with ventilation-refractory hypercapnia and respiratory acidosis due to severe, refractory status asthmaticus.     

机械通气策略在体外膜肺氧合过程中的应用

体外膜肺氧合是一种为常规治疗(机械通气)难以治愈的呼吸衰竭患者提供了临时体外呼吸循环支持的技术,在静脉-静脉体外膜肺氧合的过程中,血液从患者的静脉系统进入人工膜肺,进行氧合与二氧化碳的去除,随之再从静脉系统回输至患者体内。为了避免正常肺功能的丧失,机械通气在体外膜肺氧合的过程中仍然有必要,但如何设置体外膜肺氧合过程中的机械通气参数,至今没有明确的指南。因此,本文将简述体外膜肺氧合期间气体交换的病理生理学机制,并就现有证据和文献总结体外膜肺氧合过程中的机械通气策略。     

Successful extracorporeal lung assistance for overwhelming pneumonia in a patient with undiagnosed full blown aids--a controversial therapy in HIV-patients

A case is described of overwhelming pneumonia in a patient with a history of coughing since three months. Because of hypoxia and hypercapnia that could not be managed by optimal mechanical ventilation, the patient required urgent extracorporeal lung assistance (ECLA, also known as ECMO). Afterwards the diagnosis of full blown AIDS was made. Appropriate antiviral, antibiotic and antimycotic therapy was successfully established. The patient was weaned from ECLA 4 days later, and discharged from hospital after two months.     

Age and cardiac surgery. Influence on extravascular lung water

This study was designed in order to evaluate the influence of advanced age on extravascular lung water (EVLW) content. Forty patients undergoing aortocoronary bypass grafting were prospectively divided into two groups according to age below 45 years (group 1; n = 20) and above 65 years (group 2; n = 20). The EVLW was measured using the double indicator dilution technique with indocyanine green as the nondiffusible indicator. Starting from similar baseline values before extracorporeal circulation (ECC), EVLW significantly increased after ECC only in the elderly patients (max + 1.51 ml/kg), whereas lung water content in the other group remained almost unchanged. No significant differences in left ventricular filling pressure (PCP) could be observed. Regression analysis revealed a strong positive correlation between age and increase in EVLW after ECC. Simultaneously, PaO2 was decreased (-114 mm Hg) and intrapulmonary shunt fraction (Qs/Qt) was increased only in this group. Within the next five hours after ECC, lung water returned nearly to baseline values and pulmonary function was normalized. It is concluded that increasing age was associated with a transient increase in EVLW after ECC due to a more pronounced fragility of the pulmonary endothelial membrane or/and to depressed left ventricular performance.     

Extravascular lung water and hemofiltration during complicated cardiac surgery

Hemofiltration (HF) is an established method for treating patients with impaired renal function and excessive fluid retention. In cardiac surgery fluid accumulation during extracorporeal circulation (ECC) may contribute to postoperative organ dysfunction, leading to severe pulmonary insufficiency. In this study our experiences with hemofiltration installed in the cardiopulmonary bypass are demonstrated in patients with preoperative pulmonary edema, impaired renal function, and long-term ECC, proving its efficacy by measurement of extravascular lung water (EVLW) in the early post-bypass period. EVLW-measurement was performed using the thermal-dye technique with indocyanine green and a microprocessed lung water computer. Our data demonstrate that hemofiltration during ECC is a valuable method for controlling fluid balance. It facilitates the intra- and postoperative management of patients with end-stage renal failure or with preoperative pulmonary edema. HF seems to be helpful by decreasing the risk of complications such as fluid overload, which is demonstrated by measurement of EVLW.     

Oxygenated right ventricular assist device with a percutaneous dual-lumen cannula as a bridge to lung transplantation

BackgroundOxygenated right ventricular assist device (oxyRVAD) placement has become more streamlined with the introduction of the dual-lumen pulmonary artery cannula. Peripherally cannulated oxyRVAD may provide oxygenation support with right heart support as an alternative to venoarterial extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation.MethodsA single-institution, retrospective analysis was performed on patients placed on oxyRVAD with a dual-lumen pulmonary artery cannula with the intention of bridging to lung transplantation in 2019.ResultsFour patients with idiopathic pulmonary fibrosis were placed on oxyRVAD as a bridge to transplantation. Two patients were extubated and ambulated while waiting for a lung offer, and two patients required conversion to venoarteriovenous ECMO (VAV ECMO) from oxyRVAD. The median waiting time for extracorporeal life support (ECLS) was 42 h. All patients underwent double lung transplantation. Two patients stayed on oxyRVAD, and one patient was placed on venovenous ECMO (VV ECMO) after transplantation. Primary graft dysfunction score at 72 h after transplantation was grade 1 in three patients and grade 3 in one patient.ConclusionsPeripherally cannulated oxyRVAD with percutaneous dual-lumen venous cannula could be an ambulatory bridge for lung transplantation. It is unknown whether oxyRVAD is feasible as a long-term bridge to lung transplantation.     

Weaning from mechanical ventilation: current controversies

As an acute episode of respiratory failure resolves for the patient who is receiving mechanical ventilation, the sometimes difficult task of resuming spontaneous ventilation begins. The resumption of spontaneous ventilation, commonly referred to as weaning, is often difficult for the patient with preexisting lung disease. The purpose of this article is to explore the current controversies related to weaning patients from mechanical ventilation. Patients with chronic obstructive pulmonary disease are used as examples, providing the background for understanding weaning in difficult cases. Weaning is conceptualized as a process of three phases: preweaning, weaning, and extubation. Important considerations during each phase are examined.     

The influence of extracorporeal circulation on extravascular lung water in coronary surgery patients

The influence of extracorporeal circulation (ECC) on extravascular lung water (EVLW) was investigated in a total of 45 consenting patients undergoing coronary artery bypass surgery. The patients were subdivided into 3 groups according to positive fluid balance during ECC: 1. less than 500 ml; 2. 500 to 1500 ml; 3. 1500 to 3000 ml. Lung water measurement was performed intraoperatively using the thermal green-dye double indicator dilution technique, with indocyanine green and a microprocessed lung water computer, before and after ECC. In the group with high positive fluid balance during ECC (group 3) EVLW - increase was more pronounced (5.18 ml/kg----8.18 ml/kg) than in the groups with lower positive fluid input (group 1: 5.35 ml/kg----5.68 ml/kg, group 2: 5.56 ml/kg----6.70 ml/kg). Extravascular lung water increase was accompanied by a deterioration of pulmonary gas exchange demonstrated by the greatest decrease of paO2 in group 3 (490 mmHg----243 mmHg). No significant relationship of lung water changes to various hemodynamic parameters was observed in this study.     

电视胸腔镜下心脏手术对犬肺组织的影响

目的观察电视胸腔镜下实施犬心脏手术术后其肺组织的损伤情况。方法将30只健康幼龄犬,体质量1015 kg,随机分成3组（每组10只）,常规开胸组（A组）:按常规建立体外循环;胸腔镜组（B组）:经股动脉、股静脉插管后建立体外循环,对照组（C组）:麻醉后接呼吸机不开胸。将3组分别于麻醉诱导后（T1）、主动脉开放后30min（T2）、主动脉开放后60 min（T3）、主动脉开放后90 min（T4）时,测定血流动力学、肺顺应性、气道阻力及动脉血气分析,并根据公式计算动脉-肺泡氧分压比率（PaO2/PAO2）、肺血管阻力指数（PVRI）、氧合指数（OI）等指标。术后测定各组肺组织的含水量（W/D）、丙二醛（MDA）含量,并进行病理分析。结果术后各时间点,B组较A组的气道阻力、PVRI略高;肺顺应性、PaO2/PAO2、OI略低,但两组相比较无显著统计学差异。术后两组W/D、MDA的含量均增高,B组略高于A组,但统计学分析无显著意义。C组各指标无明显差异,与两手术组比较,气道阻力、PVRI、W/D、MDA较低,肺顺应性、PaO2/PAO2、OI较高,有显著统计学意义。病理分析:B组肺泡结构破坏,肺组织有中性粒细胞浸润,间质水肿,与A组相近,C组肺组织结构未见异常。结论小儿胸腔镜体外循环心脏手术术后,对肺组织的影响与常规体外循环近似。     

Extrakorporale Lungenunterstützungssysteme

In severe acute lung failure, which cannot be handled by conventional therapeutic options, pump-driven systems (veno-venous extracorporeal membrane oxygenation, ECMO) or pumpless systems (interventional lung assist, iLA) can be used for extracorporeal lung assist. A veno-venous ECMO is indicated in refractory hypoxaemia and/or in severe respiratory acidosis with a pH <7.2. Survival rates of more than 50% have been reported with the use of vv-ECMO in severe ARDS. Veno-venous extracorporeal systems can supply about 50–80% of the necessary gas exchange. Thus, a more protective ventilation is possible and the extent of the ventilator-induced lung injury is limited. Pumpless devices with an arteriovenous cannulation are well suited for carbon dioxide elimination. Therefore, their primary indication is for refractory hypercapnia with respiratory acidosis. As the blood flow is generated exclusively by the arteriovenous pressure difference, a reduced cardiac pump function or a low mean arterial pressure must be considered a contraindication. Because many complications can potentially occur with the use of extracorporeal systems, close surveillance of the patient and device is essential.     

应用体外膜式人工肺氧合治疗体外循环脱机困难38例的临床经验

目的:总结心脏外科术后脱离体外循环机困难的患者接受体外膜式氧合(ECMO)治疗的临床经验。方法:2004年9月至2010年12月北京安贞医院共38例患者行ECMO治疗,男性29例,女性9例,年龄6个月～74岁,ECMO辅助时间6～280 h,平均65 h。结果:ECMO成功脱机20例(52.6%),其中14例(36.8%)痊愈,6例脱机后死亡;18例未能脱机均死亡。结论:ECMO对于体外循环脱机困难患者是一种有效的辅助措施,及早应用并积极防治ECMO并发症可提高院内生存率。     

肺移植治疗呼吸机依赖的终末期肺病三例

目的探讨肺移植治疗呼吸机依赖终末期肺病患者的合理选择、围手术期处理、撤机策略问题。方法我院2002年9月至2005年3月行15例肺移植，其中3例为术前呼吸机依赖终末期肺气肿患者，术前呼吸机依赖89、120、107d。手术行单肺移植1例，非体外循环下序贯式双侧单肺移植2例。结果3例患者分别于术后第22、6、11天脱机，第71、41、67天出院，生活质量明显改善，至今分别存活22、4、2个月。结论肺移植可有效治疗经选择的呼吸机依赖的终末期肺病。     

Clinical application of a supplement to the extracorporal circulation to produce a pulsatile flow (author's transl)]

Two groups of patients with atherosclerotic coronary artery disease, who underwent aortocoronary bypass operation, were perfused with nonpulsatile flow during extracorporeal circulation (ECC) using membrane oxygenators. One group (MO) was used as a control, while for the other group (PAD) a Pulsatile Assist Device in the arterial line was employed. This apparatus consists of a balloon of 80 ml placed inside a rigid housing. The balloon is compressed by pressurized air or expanded by vacuum supplied by a driving console. The apparatus produced pulse amplitudes between 30 and 50 mm of mercury. Other than a very short-lasting fall in mean arterial pressure, thus showing diminished peripheral resistance, no perceptable advantages were found. Base excess and pH-changes showed no differences, also the given amount of sodium bicarbonate in both groups was the same. On the other hand significantly higher hemolyses took place, increasing with the duration of pulsation. The application of the apparatus as an arterial counterpulsator was possible with limitation in only 5 of 15 patients. In all other patients after a short time massive blood foaming developed in the PAD and the attempts had to be stopped because of the risk of gas embolism. In our opinion this apparatus is an unnecessary supplement to the ECC and as an arterial counterpulsator it seems too dangerous.     

Surgical management of a patient with combined heart pathologies and lung cancer. A simultaneous coronary artery bypass surgery,aortic valve replacement,tricuspid valve repair and pulmonary resection

Coexisting coronary artery disease and significant heart valve disease represent a considerable risk factor in patients undergoing pulmonary resection. The possibility to perform concomitant (simultaneous) heart and lung surgery could be a good option for many patients.In the presented case report, the intervention was performed on two valves, triple coronary artery bypass and pulmonary resection, which has not been published in literature to date.A 68-year-old woman with coronary artery disease, aortic valve stenosis, tricuspid valve regurgitation and pulmonary disease (malignant pathology) presented with triple vessel disease, moderate aortic valve stenosis, severe tricuspid regurgitation and tumorous infiltration in the upper lobe of the left lung. She underwent combined heart and pulmonary surgery-left upper lobectomy, aortic valve replacement, tricuspid valve repair and coronary artery bypass surgery. On the eight day of surgery, she was discharged. She continues to do well on follow-up.Simultaneous cardiac surgery and pulmonary resection for malignancy become almost standard treatment of patients who require heart and lung surgery. The most often approach is midline sternotomy that enables a comfortable cardiac intervention as well as an acceptable access to lungs. The left lower lobectomy remains an exception, in which pulmonary resection during extracorporeal circulation (ECC) is more often an option of left thoracotomy. If the use of ECC is inevitable, some authors prefer pulmonary resection before starting up ECC if the location of the neoplasm does not require resection during ECC.