Pumpless extracorporeal carbon dioxide removal for life-threatening asthma

Extracorporeal membrane oxygenation (ECMO) and beyond in near fatal asthma: A comprehensive review

The treatment of choice in severe asthma exacerbations with respiratory failure includes ventilatory support, both invasive and/or non-invasive, along with different kinds of asthma medication. Of note, the rate of mortality of patients with asthma has decreased substantially in recent years mainly due to significant advances in pharmacological treatment and other management strategies. However, the risk of death in patients with severe asthma who require invasive mechanical ventilation has been estimated between 6.5% and 10.3%. When conventional measures fail, rescue strategies, such as extracorporeal membrane oxygenation (ECMO) or extracorporeal CO2 removal (ECCO2R) may need to be implemented. While ECMO does not constitute a definitive treatment per se, it can minimize further ventilator associated lung injury (VALI) and can enable diagnostic-therapeutic maneuvers that cannot be performed without ECMO such as bronchoscopy and transfer for diagnostic imaging. Asthma is one of the diseases that is associated with excellent outcomes for patients with refractory respiratory failure requiring ECMO support, as shown by the Extracorporeal Life Support Organization (ELSO) registry. Moreover, in such situations, the use of ECCO2R for rescue has been described and utilized in both children and adults and is more widely spread in different hospitals than ECMO. In this article, we aim to review the evidence for the usefulness of extracorporeal respiratory support measures in the management of severe asthma exacerbations that lead to respiratory failure.

A bi-centric experience of extracorporeal carbon dioxide removal (ECCO2 R) for acute hypercapnic respiratory failure following allogeneic hematopoietic stem cell transplantation

Acute respiratory failure (ARF) is the main reason for ICU admission following allogeneic hematopoietic stem cell transplantation (HSCT). Extracorporeal CO₂ removal (ECCO₂R) can be used as an adjunct to mechanical ventilation in patients with severe hypercapnia but has not been assessed in HSCT recipients. Retrospective analysis of all allogeneic HSCT recipients ≥18 years treated with ECCO₂R at two HSCT centers. 11 patients (m:f = 4:7, median age: 45 [IQR: 32‐58] years) were analyzed. Acute leukemia was the underlying hematologic malignancy in all patients. The time from HSCT to ICU admission was 37 [8‐79] months, and 9/11 (82%) suffered from chronic graft‐versus‐host disease (GVHD) with lung involvement. Pneumonia was the most frequent reason for ventilatory decompensation (n = 9). ECCO₂R was initiated for severe hypercapnia (P_aCO₂: 96 [84‐115] mm Hg; pH: 7.13 [7.09‐7.27]) despite aggressive mechanical ventilation (invasive, n = 9; non‐invasive, n = 2). ECCO₂R effectively resolved blood gas disturbances in all patients, but only 2/11 (18%) could be weaned off ventilatory support, and one (9%) patient survived hospital discharge. Progressive respiratory and multiorgan dysfunction were the main reasons for treatment failure. ECCO₂R was technically feasible but resulted in a low survival rate in our cohort. A better understanding of the prognosis of ARF in patients with chronic GVHD and lung involvement is necessary before its use can be reconsidered in this setting.

The use of extracorporeal CO2 removal in acute respiratory failure

Background

Chronic obstructive pulmonary disease (COPD) exacerbation and protective mechanical ventilation of acute respiratory distress syndrome (ARDS) patients induce hypercapnic respiratory acidosis.

Main text

Extracorporeal carbon dioxide removal (ECCO₂R) aims to eliminate blood CO₂ to fight against the adverse effects of hypercapnia and related acidosis. Hypercapnia has deleterious extrapulmonary consequences, particularly for the brain. In addition, in the lung, hypercapnia leads to: lower pH, pulmonary vasoconstriction, increases in right ventricular afterload, acute cor pulmonale. Moreover, hypercapnic acidosis may further damage the lungs by increasing both nitric oxide production and inflammation and altering alveolar epithelial cells. During an exacerbation of COPD, relieving the native lungs of at least a portion of the CO₂ could potentially reduce the patient's respiratory work, Instead of mechanically increasing alveolar ventilation with MV in an already hyperinflated lung to increase CO₂ removal, the use of ECCO₂R may allow a decrease in respiratory volume and respiratory rate, resulting in improvement of lung mechanic. Thus, the use of ECCO₂R may prevent noninvasive ventilation failure and allow intubated patients to be weaned off mechanical ventilation. In ARDS patients, ECCO₂R may be used to promote an ultraprotective ventilation in allowing to lower tidal volume, plateau (Pplat) and driving pressures, parameters that have identified as a major risk factors for mortality. However, although ECCO₂R appears to be effective in improving gas exchange and possibly in reducing the rate of endotracheal intubation and allowing more protective ventilation, its use may have pulmonary and hemodynamic consequences and may be associated with complications.

Conclusion

In selected patients, ECCO₂R may be a promising adjunctive therapeutic strategy for the management of patients with severe COPD exacerbation and for the establishment of protective or ultraprotective ventilation in patients with ARDS without prognosis-threatening hypoxemia.

Extracorporeal and advanced therapies for progressive refractory near-fatal acute severe asthma in children

Asthma is the most common chronic illness and is one of the most common medical emergencies in children. Progressive refractory near-fatal asthma requiring intubation and mechanical ventilation can lead to death. Extracorporeal membrane oxygenation (ECMO) can provide adequate gas exchange during acute respiratory failure although data on outcomes in children requiring ECMO support for status asthmaticus is sparse with one study reporting survival rates of nearly 85% with asthma being one of the best outcome subsets for patients with refractory respiratory failure requiring ECMO support. We describe the current literature on the use of ECMO and other advanced extracorporeal therapies available for children with acute severe asthma. We also review other advanced invasive and noninvasive therapies in acute severe asthma both before and while on ECMO support.

The use of extracorporeal carbon dioxide removal in acute chronic obstructive pulmonary disease exacerbation: a narrative review

Chronic obstructive pulmonary disease (COPD) exacerbation induces hypercapnic respiratory acidosis. Extracorporeal carbon dioxide removal (ECCO2R) aims to eliminate blood carbon dioxide (CO2) in order to reduce adverse effects from hypercapnia and the related acidosis. Hypercapnia has deleterious extra-pulmonary consequences in increasing intracranial pressure and inducing and/or worsening right heart failure. During COPD exacerbation, the use of ECCO2R may improve the efficacy of non-invasive ventilation (NIV) in terms of CO2 removal, decrease respiratory rate and reduce dynamic hyperinflation and intrinsic positive end expiratory pressure, which all contribute to increasing dead space. Moreover, ECCO2R may prevent NIV failure while facilitating the weaning of intubated patients from mechanical ventilation. In this review of the literature, the authors will present the current knowledge on the pathophysiology related to COPD, the principles of the ECCO2R technique and its role in acute and severe decompensation of COPD. However, despite technical advances, there are only case series in the literature and few prospective studies to clearly establish the role of ECCO2R in acute and severe COPD decompensation.

Update on extracorporeal carbon dioxide removal: a comprehensive review on principles, indications, efficiency, and complications

TECHNOLOGY

Extracorporeal carbon dioxide removal means the removal of carbon dioxide from the blood across a gas exchange membrane without substantially improving oxygenation. Carbon dioxide removal is possible with substantially less extracorporeal blood flow than needed for oxygenation. Techniques for extracorporeal carbon dioxide removal include (1) pumpless arterio-venous circuits, (2) low-flow venovenous circuits based on the technology of continuous renal replacement therapy, and (3) venovenous circuits based on extracorporeal membrane oxygenation technology.

INDICATIONS

Extracorporeal carbon dioxide removal has been shown to enable more protective ventilation in acute respiratory distress syndrome patients, even beyond the so-called "protective" level. Although experimental data suggest a benefit on ventilator induced lung injury, no hard clinical evidence with respect to improved outcome exists. In addition, extracorporeal carbon dioxide removal is a tool to avoid intubation and mechanical ventilation in patients with acute exacerbated chronic obstructive pulmonary disease failing non-invasive ventilation. This concept has been shown to be effective in 56-90% of patients. Extracorporeal carbon dioxide removal has also been used in ventilated patients with hypercapnic respiratory failure to correct acidosis, unload respiratory muscle burden, and facilitate weaning. In patients suffering from terminal fibrosis awaiting lung transplantation, extracorporeal carbon dioxide removal is able to correct acidosis and enable spontaneous breathing during bridging. Keeping these patients awake, ambulatory, and breathing spontaneously is associated with favorable outcome.

COMPLICATIONS

Complications of extracorporeal carbon dioxide removal are mostly associated with vascular access and deranged hemostasis leading to bleeding. Although the spectrum of complications may differ, no technology offers advantages with respect to rate and severity of complications. So called "high-extraction systems" working with higher blood flows and larger membranes may be more effective with respect to clinical goals.

Extracorporeal carbon dioxide removal in heart-beating donor with acute severe asthma: A case report

Status asthmaticus is a life-threatening disorder that can manifest in dangerous levels of hypercapnia and acidosis. The use of extracorporeal carbon dioxide removal (ECCO2R) has been used successfully to control pH and PaCO₂ in patients with acute severe asthma. The present report describes the use of this technology in near-fatal asthma with brain death, and awaiting organ harvest. The ProLUNG® system consists of a veno-venous hemoperfusion circuit with an artificial lung polymethylpentene membrane coated with phosphorylcholine with a surface of 1.81 m². The system can reach a blood flow of 450 ml/min trough a double-lumen central venous catheter (13.0 Fr) placed in femoral, subclavian or jugular vein. The platform is provided with automated management of airflow and VCO₂ monitoring during treatment. The patient was maintained on extracorporeal treatment ensuring stable arterial pH control and PaCO₂ control. In acute status asthmaticus, complicated with cardiac arrest, mini-invasive ECCO2R was an effective method of controlling pH and PaCO₂, for optimizing hemodynamic and aerobic metabolism and for performing protective ventilation for an optimal organ donor preservation until the organ harvest occurs.

Extracorporeal carbon dioxide removal for lowering the risk of mechanical ventilation: research questions and clinical potential for the future

As a result of technical improvements, extracorporeal carbon dioxide removal (ECCO₂R) now has the potential to play an important role in the management of adults with acute respiratory failure. There is growing interest in the use of ECCO₂R for the management of both hypoxaemic and hypercapnic respiratory failure. However, evidence to support its use is scarce and several questions remain about the best way to implement this therapy, which can be associated with serious side-effects. This Review reflects the consensus opinion of an international group of clinician scientists with expertise in managing acute respiratory failure and in using ECCO₂R therapies in this setting. We concisely review clinically relevant aspects of ECCO₂R, and provide a series of recommendations for clinical practice and future research, covering topics that include the practicalities of ECCO₂R delivery, indications for use, and service delivery.

Extracorporeal carbon dioxide removal for acute hypercapnic respiratory failure

In the past, the only treatment of acute exacerbations of obstructive diseases with hypercapnic respiratory failure refractory to medical treatment was invasive mechanical ventilation (IMV). Considerable technical improvements transformed extracorporeal techniques for carbon dioxide removal in an attractive option to avoid worsening respiratory failure and respiratory acidosis, and to potentially prevent or shorten the duration of IMV in patients with exacerbation of COPD and asthma. In this review, we will present a summary of the pathophysiological rationale and evidence of ECCO₂R in patients with severe exacerbations of these pathologies.

Extracorporeal Gas Exchange

Extracorporeal gas exchange is increasingly used for various indications. Among these are refractory acute respiratory failure, including the acute respiratory distress syndrome (ARDS), and the avoidance of ventilator-induced lung injury (VILI) by enabling lung-protective ventilation. Additionally, extracorporeal gas exchange allows the treatment of hypercapnic respiratory failure while helping to unload the respiratory muscles and avoid intubation and invasive ventilation, as well as facilitating weaning from the ventilator. These indications are based on a reasonable physiologic rationale but must be weighed against the costs and complications associated with the technique. This article summarizes current evidence and indications for extracorporeal gas exchange.

Intermittent extracorporeal CO2 removal in chronic obstructive pulmonary disease patients: a fiction or an option

PURPOSE OF REVIEW

Aim of this article is to review evidence recently generated on the application of extracorporeal carbon dioxide removal (ECCO2R) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation (invasive and non invasive) for hypercapnic respiratory failure.

RECENT FINDINGS

To date, the paucity of evidences on ECCO2R to decrease the rate of noninvasive ventilation (NIV) failure and to wean hypercapnic patients from invasive mechanical ventilation (IMV) precludes to systematically apply this technology to COPD patients.

SUMMARY

Although several efforts have been made to reduce invasiveness and to improve the efficiency of extracorporeal systems, further randomized studies are needed to assess the effects of this technique on both short-term and long-term clinical outcomes.

Rescue therapeutic strategy combining ultra-protective mechanical ventilation with extracorporeal CO2 removal membrane in near-fatal asthma with severe pulmonary barotraumas: A case report

RATIONALE

Mechanical ventilation of severe acute asthma is still considered a challenging issue, mainly because of the gas trapping phenomenon with the potential for life-threatening barotraumatic pulmonary complications.

PATIENT CONCERNS

Herein, we describe 2 consecutive cases of near-fatal asthma for whom the recommended protective mechanical ventilation approach using low tidal volume of 6 mL/kg and small levels of PEEP was rapidly compromised by giant pneumomediastinum with extensive subcutaneousemphysema.

DIAGNOSES

Near fatal asthma.

INTERVENTION

A rescue therapeutic strategy combining extracorporeal CO2 removal membrane with ultra-protective extremely low tidal volume (3 mL/kg) ventilation was applied.

OUTCOMES

Both patients survived hospital discharge.

LESSONS

These 2 cases indicate that ECCO2R associated with ultra-protective ventilation could be an alternative to surgery in case of life-threatening barotrauma occurring under mechanical ventilation.

Extracorporeal carbon dioxide removal (ECCO2R) in patients with acute respiratory failure

PURPOSE

To review the available knowledge related to the use of ECCO₂R as adjuvant strategy to mechanical ventilation (MV) in various clinical settings of acute respiratory failure (ARF).

METHODS

Expert opinion and review of the literature.

RESULTS

ECCO₂R may be a promising adjuvant therapeutic strategy for the management of patients with severe exacerbations of COPD and for the achievement of protective or ultra-protective ventilation in patients with ARDS without life-threatening hypoxemia. Given the observational nature of most of the available clinical data and differences in technical features and performances of current devices, the balance of risks and benefits for or against ECCO₂R in such patient populations remains unclear CONCLUSIONS: ECCO₂R is currently an experimental technique rather than an accepted therapeutic strategy in ARF-its safety and efficacy require confirmation in clinical trials.

[Extracorporeal CO2 removal as an alternative to tracheotomy in a patient with extubation failure]

We report a patient with chest trauma who was admitted to the ICU after surgery. As he fulfilled protocol-based criteria, he was extubated 7 days after admission. However, despite intermittent non-invasive ventilation, the patient had to be re-intubated on day 10 owing to progressive hypercapnia. We decided to support the patient with a mid-flow veno-venous extracorporeal carbon dioxide removal (ECCO₂‑R) system instead of a tracheotomy. Sufficient CO₂ removal was established with a blood flow of 1.5 l/min and the patient was successfully extubated within a few hours. After 5 days of ECCO₂‑R the patient could be weaned and transferred to a general ward in a stable condition.

Extracorporeal carbon dioxide removal (ECCO2R) in respiratory deficiency and current investigations on its improvement: a review

The implementation of extracorporeal carbon dioxide removal (ECCO₂R) as one of the extracorporeal life support system is getting more attention today. Thus, the objectives of this paper are to study the clinical practice of commercial ECCO₂R system, current trend of its development and also the perspective on future improvement that can be done to the existing ECCO₂R system. The strength of this article lies in its review scope, which focuses on the commercial ECCO₂R therapy in the market based on membrane lung and current investigation to improve the efficiency of the ECCO₂R system, in terms of surface modification by carbonic anhydrase (CA) immobilization technique and respiratory electrodialysis (R-ED). Our methodology approach involves the identification of relevant published literature from PubMed and Web of Sciences search engine using the terms Extracorporeal Carbon Dioxide Removal (ECCO₂R), Extracorporeal life support, by combining terms between ECCO₂R and CA and also ECCO₂R with R-ED. This identification only limits articles in English language. Overall, several commercial ECCO₂R systems are known and proven safe to be used in patients in terms of efficiency, safety and risk of complication. In addition, CA-modified hollow fiber for membrane lung and R-ED are proven to have good potential to be applied in conventional ECCO₂R design. The detailed technique and current progress on CA immobilization and R-ED development were also reviewed in this article.

Feasibility and safety of low-flow extracorporeal carbon dioxide removal to facilitate ultra-protective ventilation in patients with moderate acute respiratory distress sindrome

Background

Mechanical ventilation with a tidal volume (V_T) of 6 mL/kg/predicted body weight (PBW), to maintain plateau pressure (P_plat) lower than 30 cmH₂O, does not completely avoid the risk of ventilator induced lung injury (VILI). The aim of this study was to evaluate safety and feasibility of a ventilation strategy consisting of very low V_T combined with extracorporeal carbon dioxide removal (ECCO₂R).

Methods

In fifteen patients with moderate ARDS, V_T was reduced from baseline to 4 mL/kg PBW while PEEP was increased to target a plateau pressure – (P_plat) between 23 and 25 cmH₂O. Low-flow ECCO₂R was initiated when respiratory acidosis developed (pH < 7.25, PaCO₂ > 60 mmHg). Ventilation parameters (V_T, respiratory rate, PEEP), respiratory compliance (C_RS), driving pressure (DeltaP = V_T/C_RS), arterial blood gases, and ECCO₂R system operational characteristics were collected during the period of ultra-protective ventilation. Patients were weaned from ECCO₂R when PaO₂/FiO₂ was higher than 200 and could tolerate conventional ventilation settings. Complications, mortality at day 28, need for prone positioning and extracorporeal membrane oxygenation, and data on weaning from both MV and ECCO₂R were also collected.

Results

During the 2 h run in phase, V_T reduction from baseline (6.2 mL/kg PBW) to approximately 4 mL/kg PBW caused respiratory acidosis (pH < 7.25) in all fifteen patients. At steady state, ECCO₂R with an average blood flow of 435 mL/min and sweep gas flow of 10 L/min was effective at correcting pH and PaCO₂ to within 10 % of baseline values. PEEP values tended to increase at V_T of 4 mL/kg from 12.2 to 14.5 cmH₂O, but this change was not statistically significant. Driving pressure was significantly reduced during the first two days compared to baseline (from 13.9 to 11.6 cmH₂O; p < 0.05) and there were no significant differences in the values of respiratory system compliance. Rescue therapies for life threatening hypoxemia such as prone position and ECMO were necessary in four and two patients, respectively. Only two study-related adverse events were observed (intravascular hemolysis and femoral catheter kinking).

Conclusions

The low-flow ECCO₂R system safely facilitates a low volume, low pressure ultra-protective mechanical ventilation strategy in patients with moderate ARDS.

Extracorporeal Membrane Oxygenation (ECMO)/Extracorporeal Carbon Dioxide Removal (ECCO2R)

Extracorporeal membrane oxygenation (ECMO) is a means of supporting severe pulmonary and cardiac dysfunction. It stabilizes critical derangements of oxygenation and ventilation, allowing time to diagnose, treat, and recover from the underlying cause of organ failure. The extracorporeal circuit has three main components: large-bore cannulae and circuit tubing to provide access to the native circulation, an artificial membrane lung to provide gas exchange, and an active pump to facilitate perfusion. Multiple clinical studies have evaluated this technology, the strongest evidence to date supporting its use being the Conventional Ventilation or ECMO for Severe Adult Respiratory Failure (CESAR) trial, which showed survival advantage when patients were treated with a protocol that included ECMO. Extracorporeal carbon dioxide removal (ECCO₂R) is similar in concept to ECMO, but has a lower flow rate and does not significantly oxygenate the patient. It is a primary treatment for hypercarbic respiratory failure or is an adjunct to reduce potentially injurious levels of mechanical ventilator support in hypoxemic respiratory failure. Complications are common occurrences on both types of therapy. Strong institutional commitment and a team approach are critical to successful implementation. Additional randomized trials are needed to clarify the appropriate indications and best practices for these lifesaving therapies.

Management of critical asthma syndrome during pregnancy

One-third of pregnant asthmatics experience a worsening of their asthma that may progress to a critical asthma syndrome (CAS) that includes status asthmaticus (SA) and near-fatal asthma (NFA). Patients with severe asthma before pregnancy may experience more exacerbations, especially during late pregnancy. Prevention of the CAS includes excellent asthma control involving targeted early and regular medical care of the pregnant asthmatic, together with medication compliance. Spontaneous abortion risk is higher in pregnant women with uncontrolled asthma than in non-asthmatics. Should CAS occur during pregnancy, aggressive bronchodilator therapy, montelukast, and systemic corticosteroids can be used in the context of respiratory monitoring, preferably in an Intensive Care Unit (ICU). Systemic epinephrine should be avoided due to potential teratogenic side-effects and placental/uterine vasoconstriction. Non-invasive ventilation has been used in some cases. Intratracheal intubation can be hazardous and rapid-sequence intubation by an experienced physician is recommended. Mechanical ventilation parameters are adjusted based on changes to respiratory mechanics in the pregnant patient. An inhaled helium-oxygen gas admixture may promote laminar airflow and improve gas exchange. Permissive hypercapnea is controversial, but may be unavoidable. Sedation with propofol which itself has bronchodilating properties is preferred to benzodiazepines. Case reports delineating good outcomes for both mother and fetus despite intubation for SA suggest that multidisciplinary ICU care of the pregnant asthmatic with critical asthma are feasible especially if hypoxemia is avoided.

Mechanical ventilation for severe asthma

Acute exacerbations of asthma can lead to respiratory failure requiring ventilatory assistance. Noninvasive ventilation may prevent the need for endotracheal intubation in selected patients. For patients who are intubated and undergo mechanical ventilation, a strategy that prioritizes avoidance of ventilator-related complications over correction of hypercapnia was first proposed 30 years ago and has become the preferred approach. Excessive pulmonary hyperinflation is a major cause of hypotension and barotrauma. An appreciation of the key determinants of hyperinflation is essential to rational ventilator management. Standard therapy for patients with asthma undergoing mechanical ventilation consists of inhaled bronchodilators, corticosteroids, and drugs used to facilitate controlled hypoventilation. Nonconventional interventions such as heliox, general anesthesia, bronchoscopy, and extracorporeal life support have also been advocated for patients with fulminant asthma but are rarely necessary. Immediate mortality for patients who are mechanically ventilated for acute severe asthma is very low and is often associated with out-of-hospital cardiorespiratory arrest before intubation. However, patients who have been intubated for severe asthma are at increased risk for death from subsequent exacerbations and must be managed accordingly in the outpatient setting.

Coming to terms with tissue engineering and regenerative medicine in the lung

Lung diseases such as emphysema, interstitial fibrosis, and pulmonary vascular diseases cause significant morbidity and mortality, but despite substantial mechanistic understanding, clinical management options for them are limited, with lung transplantation being implemented at end stages. However, limited donor lung availability, graft rejection, and long-term problems after transplantation are major hurdles to lung transplantation being a panacea. Bioengineering the lung is an exciting and emerging solution that has the ultimate aim of generating lung tissues and organs for transplantation. In this article we capture and review the current state of the art in lung bioengineering, from the multimodal approaches, to creating anatomically appropriate lung scaffolds that can be recellularized to eventually yield functioning, transplant-ready lungs. Strategies for decellularizing mammalian lungs to create scaffolds with native extracellular matrix components vs. de novo generation of scaffolds using biocompatible materials are discussed. Strengths vs. limitations of recellularization using different cell types of various pluripotency such as embryonic, mesenchymal, and induced pluripotent stem cells are highlighted. Current hurdles to guide future research toward achieving the clinical goal of transplantation of a bioengineered lung are discussed.

Partial extracorporeal carbon dioxide removal using a standard continuous renal replacement therapy device: a preliminary study

To test the feasibility, safety, and efficacy of partial extracorporeal CO2 removal (PECCO2R) using a standard continuous renal replacement (CRRT) device with a pediatric oxygenation membrane introduced into the circuit in a serial manner. In this retrospective single-center study, we have studied mechanically ventilated patients with persistent significant respiratory acidosis and acute renal failure requiring ongoing CRRT. Sixteen patients were treated with our PECCO2R device. PaCO2 and arterial pH were measured before as well as at 6 and 12 hours after PECCO2R implementation. Hemodynamic parameters were continuously monitored. Our PECCO2R system was efficient to significantly reduce PaCO2 and increase arterial pH. The median PaCO2 before treatment was 77 mm Hg (59-112) with a median reduction of 24 mm Hg after 6 hours and 30 mm Hg after 12 hours (31% and 39%, respectively). The median pH increase was 0.16 at 6 hours and 0.23 at 12 hours. Partial extracorporeal CO2 removal treatment had no effect on oxygenation. No complication was observed. Our PECCO2R approach based on the simple introduction of a pediatric extracorporeal membrane oxygenation membrane into the circuit of a standard CRRT device is easy to implement, safe, and efficient to improve respiratory acidosis.

Extracorporeal Co2 removal in hypercapnic patients at risk of noninvasive ventilation failure: a matched cohort study with historical control

OBJECTIVES

To assess efficacy and safety of noninvasive ventilation-plus-extracorporeal Co2 removal in comparison to noninvasive ventilation-only to prevent endotracheal intubation patients with acute hypercapnic respiratory failure at risk of failing noninvasive ventilation.

DESIGN

Matched cohort study with historical control.

SETTING

Two academic Italian ICUs.

PATIENTS

Patients treated with noninvasive ventilation for acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease (May 2011 to November 2013).

INTERVENTIONS

Extracorporeal CO2 removal was added to noninvasive ventilation when noninvasive ventilation was at risk of failure (arterial pH ≤ 7.30 with arterial PCO2 > 20% of baseline, and respiratory rate ≥ 30 breaths/min or use of accessory muscles/paradoxical abdominal movements). The noninvasive ventilation-only group was created applying the genetic matching technique (GenMatch) on a dataset including patients enrolled in two previous studies. Exclusion criteria for both groups were mean arterial pressure less than 60 mm Hg, contraindications to anticoagulation, body weight greater than 120 kg, contraindication to continuation of active treatment, and failure to obtain consent.

MEASUREMENTS AND MAIN RESULTS

Primary endpoint was the cumulative prevalence of endotracheal intubation. Twenty-five patients were included in the noninvasive ventilation-plus-extracorporeal CO2 removal group. The GenMatch identified 21 patients for the noninvasive ventilation-only group. Risk of being intubated was three times higher in patients treated with noninvasive ventilation-only than in patients treated with noninvasive ventilation-plus-extracorporeal CO2 removal (hazard ratio, 0.27; 95% CI, 0.07-0.98; p = 0.047). Intubation rate in noninvasive ventilation-plus-extracorporeal CO2 removal was 12% (95% CI, 2.5-31.2) and in noninvasive ventilation-only was 33% (95% CI, 14.6-57.0), but the difference was not statistically different (p = 0.1495). Thirteen patients (52%) experienced adverse events related to extracorporeal CO2 removal. Bleeding episodes were observed in three patients, and one patient experienced vein perforation. Malfunctioning of the system caused all other adverse events.

CONCLUSIONS

These data provide the rationale for future randomized clinical trials that are required to validate extracorporeal CO2 removal in patients with hypercapnic respiratory failure and respiratory acidosis nonresponsive to noninvasive ventilation.

Extracorporeal life support devices and strategies for management of acute cardiorespiratory failure in adult patients: a comprehensive review

Evolution of extracorporeal life support (ECLS) technology has added a new dimension to the intensive care management of acute cardiac and/or respiratory failure in adult patients who fail conventional treatment. ECLS also complements cardiac surgical and cardiology procedures, implantation of long-term mechanical cardiac assist devices, heart and lung transplantation and cardiopulmonary resuscitation. Available ECLS therapies provide a range of options to the multidisciplinary teams who are involved in the time-critical care of these complex patients. While venovenous extracorporeal membrane oxygenation (ECMO) can provide complete respiratory support, extracorporeal carbon dioxide removal facilitates protective lung ventilation and provides only partial respiratory support. Mechanical circulatory support with venoarterial (VA) ECMO employed in a traditional central/peripheral fashion or in a temporary ventricular assist device configuration may stabilise patients with decompensated cardiac failure who have evidence of end-organ dysfunction, allowing time for recovery, decision-making, and bridging to implantation of a long-term mechanical circulatory support device and occasionally heart transplantation. In highly selected patients with combined severe cardiac and respiratory failure, advanced ECLS can be provided with central VA ECMO, peripheral VA ECMO with timely transition to venovenous ECMO or VA-venous ECMO upon myocardial recovery to avoid upper body hypoxia or by addition of an oxygenator to the temporary ventricular assist device circuit. This article summarises the available ECLS options and provides insights into the principles and practice of these techniques. One should emphasise that, as is common with many emerging therapies, their optimal use is currently not backed by quality evidence. This deficiency needs to be addressed to ensure that the full potential of ECLS can be achieved.

Extracorporeal life support for acute respiratory distress syndromes

The morbidity and mortality of acute respiratory distress syndrome remain to be high. Over the last 50 years, the clinical management of these patients has undergone vast changes. Significant improvement in the care of these patients involves the development of mechanical ventilation strategies, but the benefits of these strategies remain controversial. With a growing trend of extracorporeal support for critically ill patients, we provide a historical review of extracorporeal membrane oxygenation (ECMO) including its failures and successes as well as discussing extracorporeal devices now available or nearly accessible while examining current clinical indications and trends of ECMO in respiratory failure.

Extracorporeal pulmonary support in severe pulmonary failure in adults: a treatment rediscovered

BACKGROUND

Severe, acute respiratory failure in adults still carries a high mortality. In recent years, improved pulmonary support techniques have been used increasingly alongside conventional treatment. About 1000 such treatments are performed in Germany annually, and the number is rising rapidly. The two types of systems currently in use involve venovenous extracorporeal membrane oxygenation (ECMO) and extracorporeal carbon dioxide elimination.

METHODS

The underlying principles, technical implementation, efficacy, and adverse effects of the new techniques are summarized in the light of a selective review of the literature, supplemented by the authors' personal experience. Recommendations are given for clinical use.

RESULTS

Currently, only limited high-quality data (from prospective randomized trials) are available to support the use of either of these techniques in adults. Veno-venous ECMO systems can effectively secure gas exchange in patients with severe respiratory failure, with experienced centers reporting survival rates from 63% to 75%. Either pump-free arteriovenous systems or low-flow ECMO systems can be used for extracorporeal carbon dioxide elimination. Complications can be serious or life-threatening and must, therefore, be rapidly recognized and treated: these include vascular injury during cannulation, venous thrombosis in a cannulated vessel, an increased hemorrhagic tendency, and thrombocytopenia.

CONCLUSION

Modern miniaturized pulmonary support systems enable protective mechanical ventilation with low tidal volumes, reduce ventilator-associated lung injury, and can improve survival rates in critically ill patients with a manageable adverse effect profile.

Pediatric status asthmaticus

Status asthmaticus is a frequent cause of admission to a pediatric intensive care unit. Prompt assessment and aggressive treatment are critical. First-line or conventional treatment includes supplemental oxygen, aerosolized albuterol, and corticosteroids. There are several second-line treatments available; however, few comparative studies have been performed and in the absence of good evidence-based treatments, the use of these therapies is highly variable and dependent on local practice and provider preference. In this article the pathophysiology and treatment of status asthmaticus is discussed, and the literature regarding second-line treatments is critically assessed to apply an evidence basis to the treatment of this severe disease.

Bench to bedside review: Extracorporeal carbon dioxide removal, past present and future

Acute respiratory distress syndrome (ARDS) has a substantial mortality rate and annually affects more than 140,000 people in the USA alone. Standard management includes lung protective ventilation but this impairs carbon dioxide clearance and may lead to right heart dysfunction or increased intracranial pressure. Extracorporeal carbon dioxide removal has the potential to optimize lung protective ventilation by uncoupling oxygenation and carbon dioxide clearance. The aim of this article is to review the carbon dioxide removal strategies that are likely to be widely available in the near future. Relevant published literature was identified using PubMed and Medline searches. Queries were performed by using the search terms ECCOR, AVCO2R, VVCO2R, respiratory dialysis, and by combining carbon dioxide removal and ARDS. The only search limitation imposed was English language. Additional articles were identified from reference lists in the studies that were reviewed. Several novel strategies to achieve carbon dioxide removal were identified, some of which are already commercially available whereas others are in advanced stages of development.

[Extracorporeal lung support]

For decades, techniques for extracorporeal lung support, such as extracorporeal membrane oxygenation (ECMO), have offered in specialized centres the possibility to completely or partly substitute lung function, thus, facilitating healing. Initially the application of ECMO was associated with severe complications, but significant technical progress in recent years has led to the development of safer systems and promotes a wider distribution of the technique. Supported by recent, positive study data, ECMO has become a promising option for acute respiratory distress syndrome (ARDS) therapy in specialized centers. Further developments and modifications, such as pumpless devices for extracorporeal lung support have the potential of becoming an interesting option for intensive care medicine - however, data of prospective studies showing efficacy are still not available.

Perioperative lung protection strategies in cardiothoracic anesthesia: are they useful?

Patients are at risk for several types of lung injury in the perioperative period. These injuries include atelectasis, pneumonia, pneumothorax, bronchopleural fistula, acute lung injury, and acute respiratory distress syndrome. Anesthetic management can cause, exacerbate, or ameliorate most of these injuries. Lung-protective ventilation strategies using more physiologic tidal volumes and appropriate levels of positive end-expiratory pressure can decrease the extent of this injury. This review discusses the effects of mechanical ventilation and its role in ventilator-induced lung injury with specific reference to cardiothoracic anesthesia.

Extracorporeal Carbon Dioxide Removal (ECCO2R) in Respiratory Failure: An Overview, and where Next?

Extracorporeal carbon dioxide removal (ECCO2R) is used to facilitate protective ventilation strategies and to treat severe hypercapnic acidosis that is refractory to mechanical ventilation. There is an increasing amount of interest in the use of ECCO2R but there are no recommendations for its use that take the most recent evidence into account. In 2008, the National Institute of Health and Clinical Excellence (NICE) published guidelines on ‘Arteriovenous Extracorporeal Membrane Carbon Dioxide Removal.’1 However, since that time there have been a number of studies in the area and some significant technological advances including the introduction of commercially available VV-ECCO2R systems. The aim of this article is to provide an overview of ECCO2R, review the literature relating to its use and discuss its future role in the intensive care setting.

[Decubitus prone position in patient with extracorporeal CO2 removal device Novalung(®)]

OBJECTIVE

To describe the course of a patient with the extracorporeal CO2 removal device and discover the effect of Novalung on ventilation, considering the patient's prone position and its influence on the device's blood flow. To develop a protocol of managing and specific care of a patient with Novalung.

MATERIAL AND METHODS

A case report of a patient with Novalung in a tertiary hospital ICU unit is reported. Parameters considered are hemodynamic, respiratory, pharmacological, analytical, neuromonitoring, managing of the Novalung and length of decubitus prone cycles. Anova Test, Student's T test, Wilcoxon-Mann Whitney and Spearman correlation. Significance p <0.05.

RESULTS

A 46-year old women with nosocomial pneumonia and acute respiratory failure with indication of Novalung to decrease hypercapnia and optimize ventilatory management of refractory hypoxemia. ICU Stay 26 days, MBP 82 ± 9 mmHg, HR 110 ± 6l pm during the admission, monitoring PICCO 5 days CI 3.2 ± 0.8 l/min/m2, ELWI 33 ± 4 ml, continuous hemofiltration 13.2 days with a median removal 50 cc/h. Norepinephrine dose 0.68 ± 0.79 μ/kg/min for 15 days. Respiratory parameters during the admission: PO2 59 ± 13 mmHg, PCO2 68 ± 35 mmHg, SatO2 85 ± 12%, PO2/FIO2 69 ± 35, tidal volume 389 ± 141 cc. Novalung® 13 days, heparin dose 181.42 ± 145 mIU/Kg/min, Cephalin time 57.56 ± 16.41 sec, O2 flow 7 ± 3 l/min, median blood flow 1030 cc/h, interquartile range 1447-612 cc/h. Prone cycles 4, duration 53 ± 27 hours. With Novalung® PCO2 decreased regardless of position 66 ± 21:56 ± 9, p=0.005. Tidal volume 512 ± 67:267 ± 72, p=0.0001. Blood flow on supine-prone position 1053 ± 82:113 ± 112, p=0.001. There was no link between blood flow and PCO2 (p=0.2) and between O2 and PO2 flow (p=0.05). Specific care: pedal and tibial pulse monitoring, keep circuit safe to prevent and detect signs of bleeding, femoral arterial and venous catheter care, coagulation monitoring.

COMMENTS

During the use of Novalung protective, ventilation, low tidal volumes, decreased pressure plateau, PEEP and hypercapnia were achieved. Blood flow decreased in prone position, but the PCO2 did not increase. The device did not coagulate.

[Respiratory pump failure. Clinical symptoms, diagnostics and therapy]

The total anatomical and functional apparatus which allows normal ventilation of the lungs is known as the respiratory pump. An insufficiency of this system, which can be caused by a multitude of reasons, primarily affects the inspiratory musculature and especially the diaphragm. One of the essential clinical characteristics is rapid shallow breathing. Exhaustion of the repiratory musculature due to acute respiratory insufficiency is normally clinically registered but can also be functionally determined in particular by the maximum static inspiratory closed mouth pressure. A further option is invasive measurement of the transdiaphragmal pressure, which however is not suitable as a routine procedure. Mechanical ventilation is used as treatment of respiratory pump insufficiency independent of the cause. This is initially a non-invasive procedure but if unsuccessful intubation and invasive ventilation are indicated. The technical developments in the field of extracorporeal gas exchange systems are very promising. However, in view of the insufficient data, ventilation procedures using masks and tubes still remain the first choice methods.

Extracorporeal CO(2) removal in ARDS

Acute respiratory distress syndrome remains one of the most clinically vexing problems in critical care. As technology continues to evolve, it is likely that extracorporeal CO(2) removal devices will become smaller, more efficient, and safer. As the risk of extracorporeal support decreases, devices' role in acute respiratory distress syndrome patients remains to be defined. This article discusses the functional properties and management techniques of CO(2) removal and intracorporeal membrane oxygenation and provides a glimpse into the future of long-term gas-exchange devices.

Physiologic effect and safety of the pumpless extracorporeal interventional lung assist system in patients with acute respiratory failure--a pilot study

Interventional lung assist (iLA) effectively reduces CO(2) tension and permits protective lung ventilation in patients with acute respiratory distress syndrome. However, there is little experience in using iLA in acute respiratory failure from various causes and no experience for small body sizes such as Asian patients. We evaluated the physiologic effect and safety of the iLA device in patients with acute respiratory failure from various causes. We enrolled 11 consecutive patients with severe respiratory failure from various causes. Wire-enforced cannulae (13-15 Fr) were inserted under ultrasound guidance and connected to iLA. Arterial blood gas analysis, ventilator parameters, hemodynamic parameter, and adverse events were recorded serially. During the first 24h of iLA use, mean blood flow was 1.08±0.15L/min, PaCO(2) decreased from 83.9±23.4mmHg to 40.7±10.2mmHg, and PaO(2) /FiO(2) ratio increased from 110±37 to 141±74. Minute ventilation decreased from 9.4±2.5 to 6.3±1.5L/min, and peak inspiratory pressure decreased from 30.3±7.1cm H(2) O to 28.8±9.4cm H(2) O. No serious adverse events were observed during iLA use. iLA showed effective CO(2) removal, allowed for reducing the invasiveness of mechanical ventilation in patients with severe respiratory failure from various causes even using a small-sized catheter and was safe in small body-sized patients.

Acute lung failure

Lung failure is the most common organ failure seen in the intensive care unit. The pathogenesis of acute respiratory failure (ARF) can be classified as (1) neuromuscular in origin, (2) secondary to acute and chronic obstructive airway diseases, (3) alveolar processes such as cardiogenic and noncardiogenic pulmonary edema and pneumonia, and (4) vascular diseases such as acute or chronic pulmonary embolism. This article reviews the more common causes of ARF from each group, including the pathological mechanisms and the principles of critical care management, focusing on the supportive, specific, and adjunctive therapies for each condition.

Rescue of Acute Refractory Hypercapnia and Acidosis Secondary to Life-Threatening Asthma with Extracorporeal Carbon Dioxide Removal (ECCO2R)

We report a case of life-threatening asthma associated with profound hypercapnia and acidosis that was refractory to conventional medical therapy but was managed successfully using an extracorporeal carbon dioxide removal (ECCO2R) device (NovaLung iLA®). In the UK, ECCO2R is still not widely available, with few intensivists and anaesthetists having experience of its use in routine intensive care unit practice. Extracorporeal CO2 removal may have a role in the management of acute life-threatening asthma and in preventing patient death and improving overall outcomes.

Lung protective strategies in anaesthesia

Patients are at risk for several types of lung injury in the perioperative period including atelectasis, pneumonia, pneumothorax, acute lung injury, and acute respiratory distress syndrome. Anaesthetic management can cause, exacerbate, or ameliorate these injuries. This review examines the effects of perioperative mechanical ventilation and its role in ventilator-induced lung injury. Lung protective ventilatory strategies to specific clinical situations such as cardiopulmonary bypass and one-lung ventilation along with newer novel lung protective strategies are discussed.

[Invasive mechanical ventilation in COPD and asthma]

COPD and asthmatic patients use a substantial proportion of mechanical ventilation in the ICU, and their overall mortality with ventilatory support can be significant. From the pathophysiological standpoint, they have increased airway resistance, pulmonary hyperinflation, and high pulmonary dead space, leading to increased work of breathing. If ventilatory demand exceeds work output of the respiratory muscles, acute respiratory failure follows. The main goal of mechanical ventilation in this kind of patients is to improve pulmonary gas exchange and to allow for sufficient rest of compromised respiratory muscles to recover from the fatigued state. The current evidence supports the use of noninvasive positive-pressure ventilation for these patients (especially in COPD), but invasive ventilation also is required frequently in patients who have more severe disease. The physician must be cautious to avoid complications related to mechanical ventilation during ventilatory support. One major cause of the morbidity and mortality arising during mechanical ventilation in these patients is excessive dynamic pulmonary hyperinflation (DH) with intrinsic positive end-expiratory pressure (intrinsic PEEP or auto-PEEP). The purpose of this article is to provide a concise update of the most relevant aspects for the optimal ventilatory management in these patients.

[Status asthmaticus. Role of extracorporeal lung assist procedures]

The successful application of a pumpless extracorporeal lung assist procedure ("interventional lung assist, iLA) in three cases of severe refractory status asthmaticus, which could not be solved with conventional pharmacological and respiratory therapy is reported. After an individual risk-benefit analysis such a therapy can be used to reduce lung injury due to invasive mechanical ventilation. Because of the complexity of this therapy it should only be applied in special medical centers with sufficient experience in dealing with extracorporeal lung assist procedures.

Extracorporeal life support for management of refractory cardiac or respiratory failure: initial experience in a tertiary centre

Introduction

Extracorporeal Life Support (ECLS) and extracorporeal membrane oxygenation (ECMO) have been indicated as treatment for acute respiratory and/or cardiac failure. Here we describe our first year experience of in-hospital ECLS activity, the operative algorithm and the protocol for centralization of adult patients from district hospitals.

Methods

At a tertiary referral trauma center (Careggi Teaching Hospital, Florence, Italy), an ECLS program was developed from 2008 by the Emergency Department and Heart and Vessel Department ICUs. The ECLS team consists of an intensivist, a cardiac surgeon, a cardiologist and a perfusionist, all trained in ECLS technique. ECMO support was applied in case of severe acute respiratory distress syndrome (ARDS) not responsive to conventional treatments. The use of veno-arterial (V-A) ECLS for cardiac support was reserved for cases of cardiac shock refractory to standard treatment and cardiac arrests not responding to conventional resuscitation.

Results

A total of 21 patients were treated with ECLS during the first year of activity. Among them, 13 received ECMO for ARDS (5 H1N1-virus related), with a 62% survival. In one case of post-traumatic ARDS, V-A ECLS support permitted multiple organ donation after cerebral death was confirmed. Patients treated with V-A ECLS due to cardiogenic shock (N = 4) had a survival rate of 50%. No patients on V-A ECLS support after cardiac arrest survived (N = 4).

Conclusions

In our centre, an ECLS Service was instituted over a relatively limited period of time. A strict collaboration between different specialists can be regarded as a key feature to efficiently implement the process.