A novel strategy to improve systemic oxygenation in venovenous extracorporeal membrane oxygenation: the "χ-configuration".
Venovenous extracorporeal membrane oxygenation (VV-ECMO) is used in refractory acute respiratory distress syndrome where lung recovery is the primary goal. For its achievement, adequate extracorporeal blood flow and a maximal separation between oxygenated (inflow) and deoxygenated (outflow) blood flow are essential for reducing the recirculation phenomenon. We introduce the χ-configuration, a new cannulation strategy for VV-ECMO.
We report our experience with 30 VV-ECMO consecutive patients: in 16 patients (group NS) we applied the χ-configuration, which consists of a particular right atrial cannula arrangement and a self-made modified inflow cannula, consisting of an outflow multihole venous cannula that was inserted percutaneously through the right femoral vein, into the right atrium, just below on the superior vena cava, and a self-made modified curved inflow cannula (inserted percutaneously through the right internal jugular vein) that, in its terminal segment, permitted the tip to be positioned close to the tricuspid valve. In 14 patients (group C) we applied the standard femoro-jugular VV-ECMO 2-cannula setting. In both groups, efficacy of blood oxygenation was obtained by gas-blood analysis, by blood samples obtained at arterial, central venous, and pulmonary artery lines, and by ECMO inflow and outflow lines. The recirculation fraction was obtained by a specific bedside formula.
No differences were noted between groups regarding the pre-ECMO patient characteristics. No complications during cannulation were recorded. In group NS, on-ECMO time, post-ECMO mechanical ventilation time, and ECMO overall results were significantly better than in group C. During high-flow VV-ECMO, pulmonary and systemic arterial oxygen saturation and arterial oxygen tension were significantly higher in group NS, and blood recirculation fraction was significantly lower.
Our data indicate that χ-configuration can be safe, feasible, and more effective than conventional VV-ECMO. It permits near complete drainage of the desaturated blood and a preferential oxygenated blood inflow toward the tricuspid valve, resulting in a significant reduction of recirculation, thereby improving the patient's oxygenation. Our innovative strategy reduces on-ECMO and post-ECMO mechanical ventilation time, gives a faster and better pulmonary recovery, improves survival, and can reduce hospital costs.
Bonacchi M
，Harmelin G
，Peris A
，Sani G
... -
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Extracorporeal lung support technologies - bridge to recovery and bridge to lung transplantation in adult patients: an evidence-based analysis.
For cases of acute respiratory distress syndrome (ARDS) and progressive chronic respiratory failure, the first choice or treatment is mechanical ventilation. For decades, this method has been used to support critically ill patients in respiratory failure. Despite its life-saving potential, however, several experimental and clinical studies have suggested that ventilator-induced lung injury can adversely affect the lungs and patient outcomes. Current opinion is that by reducing the pressure and volume of gas delivered to the lungs during mechanical ventilation, the stress applied to the lungs is eased, enabling them to rest and recover. In addition, mechanical ventilation may fail to provide adequate gas exchange, thus patients may suffer from severe hypoxia and hypercapnea. For these reasons, extracorporeal lung support technologies may play an important role in the clinical management of patients with lung failure, allowing not only the transfer of oxygen and carbon dioxide (CO(2)) but also buying the lungs the time needed to rest and heal.
The objective of this analysis was to assess the effectiveness, safety, and cost-effectiveness of extracorporeal lung support technologies in the improvement of pulmonary gas exchange and the survival of adult patients with acute pulmonary failure and those with end-stage chronic progressive lung disease as a bridge to lung transplantation (LTx). The application of these technologies in primary graft dysfunction (PGD) after LTx is beyond the scope of this review and is not discussed. CLINICAL APPLICATIONS OF EXTRACORPOREAL LUNG SUPPORT: Extracorporeal lung support technologies [i.e., Interventional Lung Assist (ILA) and extracorporeal membrane oxygenation (ECMO)] have been advocated for use in the treatment of patients with respiratory failure. These techniques do not treat the underlying lung condition; rather, they improve gas exchange while enabling the implantation of a protective ventilation strategy to prevent further damage to the lung tissues imposed by the ventilator. As such, extracorporeal lung support technologies have been used in three major lung failure case types: As a bridge to recovery in acute lung failure - for patients with injured or diseased lungs to give their lungs time to heal and regain normal physiologic function.As a bridge to LTx - for patients with irreversible end stage lung disease requiring LTx.As a bridge to recovery after LTx - used as lung support for patients with PGD or severe hypoxemia. EX-VIVO LUNG PERFUSION AND ASSESSMENT: Recently, the evaluation and reconditioning of donor lungs ex-vivo has been introduced into clinical practice as a method of improving the rate of donor lung utilization. Generally, about 15% to 20% of donor lungs are suitable for LTx, but these figures may increase with the use of ex-vivo lung perfusion. The ex-vivo evaluation and reconditioning of donor lungs is currently performed at the Toronto General Hospital (TGH) and preliminary results have been encouraging (Personal communication, clinical expert, December 17, 2009). If its effectiveness is confirmed, the use of the technique could lead to further expansion of donor organ pools and improvements in post-LTx outcomes. EXTRACORPOREAL LUNG SUPPORT TECHNOLOGIES: ECMO: The ECMO system consists of a centrifugal pump, a membrane oxygenator, inlet and outlet cannulas, and tubing. The exchange of oxygen and CO(2) then takes place in the oxygenator, which delivers the reoxygenated blood back into one of the patient's veins or arteries. Additional ports may be added for haemodialysis or ultrafiltration. TWO DIFFERENT TECHNIQUES MAY BE USED TO INTRODUCE ECMO: venoarterial and venovenous. In the venoarterial technique, cannulation is through either the femoral artery and the femoral vein, or through the carotid artery and the internal jugular vein. In the venovenous technique cannulation is through both femoral veins or a femoral vein and internal jugular vein; one cannula acts as inflow or arterial line, and the other as an outflow or venous line. Venovenous ECMO will not provide adequate support if a patient has pulmonary hypertension or right heart failure. Problems associated with cannulation during the procedure include bleeding around the cannulation site and limb ischemia distal to the cannulation site. ILA: Interventional Lung Assist (ILA) is used to remove excess CO(2) from the blood of patients in respiratory failure. The system is characterized by a novel, low-resistance gas exchange device with a diffusion membrane composed of polymethylpentene (PMP) fibres. These fibres are woven into a complex configuration that maximizes the exchange of oxygen and CO(2) by simple diffusion. The system is also designed to operate without the help of an external pump, though one can be added if higher blood flow is required. The device is then applied across an arteriovenous shunt between the femoral artery and femoral vein. Depending on the size of the arterial cannula used and the mean systemic arterial pressure, a blood flow of up to 2.5 L/min can be achieved (up to 5.5 L/min with an external pump). The cannulation is performed after intravenous administration of heparin. Recently, the first commercially available extracorporeal membrane ventilator (NovaLung GmbH, Hechingen, Germany) was approved for clinical use by Health Canada for patients in respiratory failure. The system has been used in more than 2,000 patients with various indications in Europe, and was used for the first time in North America at the Toronto General Hospital in 2006. EVIDENCE-BASED ANALYSIS: The research questions addressed in this report are: Does ILA/ECMO facilitate gas exchange in the lungs of patients with severe respiratory failure?Does ILA/ECMO improve the survival rate of patients with respiratory failure caused by a range of underlying conditions including patients awaiting LTx?What are the possible serious adverse events associated with ILA/ECMO therapy?To address these questions, a systematic literature search was performed on September 28, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2005 to September 28, 2008. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with an unknown eligibility were reviewed with a second clinical epidemiologist and then a group of epidemiologists until consensus was established.
Studies in which ILA/ECMO was used as a bridge to recovery or bridge to LTxStudies containing information relevant to the effectiveness and safety of the procedureStudies including at least five patients
Studies reporting the use of ILA/ECMO for inter-hospital transfers of critically ill patientsStudies reporting the use of ILA/ECMO in patients during or after LTxAnimal or laboratory studiesCase reports
Reduction in partial pressure of CO(2)Correction of respiratory acidosisImprovement in partial pressure of oxygenImprovement in patient survivalFrequency and severity of adverse eventsThe search yielded 107 citations in Medline and 107 citations in EMBASE. After reviewing the information provided in the titles and abstracts, eight citations were found to meet the study inclusion criteria. One study was then excluded because of an overlap in the study population with a previous study. Reference checking did not produce any additional studies for inclusion. Seven case series studies, all conducted in Germany, were thus included in this review (see Table 1). Also included is the recently published CESAR trial, a multicentre RCT in the UK in which ECMO was compared with conventional intensive care management. The results of the CESAR trial were published when this review was initiated. In the absence of any other recent RCT on ECMO, the results of this trial were considered for this assessment and no further searches were conducted. A literature search was then conducted for application of ECMO as bridge to LTx patients (January, 1, 2005 to current). A total of 127 citations on this topic were identified and reviewed but none were found to have examined the use of ECMO as bridge to LTx.
To grade the quality of evidence, the grading system formulated by the GRADE working group and adopted by MAS was applied. The GRADE system classifies the quality of a body of evidence as high, moderate, low, or very low according to four key elements: study design, study quality, consistency across studies, and directness.
TRIALS ON ILA: Of the seven studies identified, six involved patients with ARDS caused by a range of underlying conditions; the seventh included only patients awaiting LTx. All studies reported the rate of gas exchange and respiratory mechanics before ILA and for up to 7 days of ILA therapy. Four studies reported the means and standard deviations of blood gas transfer and arterial blood pH, which were used for meta-analysis. Fischer et al. reported their first experience on the use of ILA as a bridge to LTx. In their study, 12 patients at high urgency status for LTx, who also had severe ventilation refractory hypercapnea and respiratory acidosis, were connected to ILA prior to LTx. Seven patients had a systemic infection or sepsis prior to ILA insertion. Six hours after initiation of ILA, the partial pressure of CO(2) in arterial blood significantly decreased (P < .05) and arterial blood pH significantly improved (P < .05) and remained stable for one week (last time point reported). (ABSTRACT TRUNCATED)
Medical Advisory Secretariat
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Pediatric single-lumen cannula venovenous extracorporeal membrane oxygenation: a French center experience.
Single-lumen cannula venovenous (VV) extracorporeal membrane oxygenation (ECMO) is a special extracorporeal life support (ECLS) technique used for neonatal and pediatric refractory hypoxemia. This is an alternative flow rate ECLS that consists of successive clamping on the drainage and the injection lines. Currently, the Armand-Trousseau's pediatric intensive care unit remains the only pediatric ECMO center proposing this partial assistance. This article details a technical note and a retrospective analysis of our experience in refractory hypoxemia. The retrospective study, from 2007 to 2011, included all pediatric and neonatal patients treated by single-lumen cannula VV ECMO. The study was focused on pre-ECMO patient characteristics and complications during ECMO course. During the last 5 years, 67 pediatric patients were assisted by this single-lumen cannula VV ECMO. Sixty-one patients (91%) were newborns. Thirty-nine patients presented with meconium aspiration syndrome (58%), which was the most frequent etiology. Before cannulation, mean oxygenation index (OI) was 32 ± 11, alveolar-arterial oxygen difference was 604 ± 47 mm Hg, and partial pressure arterial oxygen/fraction inspired oxygen ratio was 59.2 ± 35.8. Forty-eight patients (72%) presented pulmonary hypertension, and 66 patients were treated by nitric oxide (98%). Fifty patients (75%) were treated by vasopressors or inotropic drugs. Average duration of ECMO was 13.2 ± 7.8 days. There were forty-six survivors (69%). The worst prognosis was for respiratory syncytial virus pneumonia. Complications like acute renal injury and hematologic and transfusion acts were not so different than those observed in classical ECMO techniques. Nevertheless, 19 patients presented a stroke (28% of the overall population), but this high rate did not seem to be due to the ECLS technique used. Single-lumen cannula VV ECMO is a partial and efficient ECMO support. Our experience shows that this technique is as efficient and less invasive than two cannulas ECMO. The single-lumen cannula VV ECMO is a simple and safe ECLS support used for neonatal or pediatric refractory hypoxemia. Because this is a partial assistance, it is a promising ECLS support.
Léger PL
，Guilbert J
，Isambert S
，Le Saché N
，Hallalel F
，Amblard A
，Chevalier JY
，Renolleau S
... -
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ResearchGate
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