Hemolytic characteristics of oxygenators during clinical extracorporeal membrane oxygenation

A connection was previously reported between the hemolytic characteristics associated with oxygenators and the pressure drop measurements in the blood chamber under experimental conditions simulating their use in cardiopulmonary bypass. We examined this association during extracorporeal membrane oxygenation (ECMO) conditions. Three oxygenators for ECMO or pediatric cardiopulmonary bypass (Menox EL4000, Dideco Module 4000, and Mera HPO-15H) were evaluated. Fresh blood from healthy Dexter strain calves anticoagulated with citrate phosphate dextrose adenine solution was used. The blood flow was fixed at 1 L/min, similar to that in ECMO. The Normalized Index of Hemolysis for Oxygenators (NIHO) has been modified according to the American Society of Testing and Materials standards, as was previously reported. The NIHO value was the lowest in the Menox (0.0070+/-0.0009) and increased from Menox to Dideco (0.0113+/-0.0099) to Mera (0.0164+/-0.0043); however, there were no significant differences among the oxygenators. This NIHO value has a close correlation to the pressure drop. In conclusion, this evaluation method is also applicable to comparison of the biocompatibility performance of different types of clinically available oxygenators for ECMO.     

Calcium homeostasis disorder during and after neonatal extracorporeal membrane oxygenation

Results:During ECMO PTH was inadequately high with normal serum calcium on day 7 (PTH: 73.54 ± 40 ng/l; calcemia: 2.33 ± 0.21 mmol/l), day 14 (PTH: 57.63 ± 29.57 ng/l; calcemia: 2.44 ± 0.43 mmol/l) and day 21 (PTH: 54.93 ± 8.43 ng/l; calcemia: 2.13 ± 0.09 mmol/l). The absence of correlation between serum calcium and PTH levels seem to confirm the dysregulation of PTH - serum calcium metabolism during ECMO. Six months after ECMO weaning, we noticed hypercalcemia with normal PTH.Conclusions:We confirmed the existence of severe disturbances of calcium homeostasis in neonates on ECMO and supposed the possible damage of calcium regulation. We did not succeed in finding clear explanations of these disturbances.     

Thrombus formation and microaggregate removal during extracorporeal membrane oxygenation.

Contemporary microporous membrane oxygenators have adequate gas transfer capacity and even prolonged oxygenation is relatively atraumatic to the blood elements. However, even with adequate heparinization, thrombus formation still takes place, albeit to a lesser degree than in direct blood-gas contact devices. In this work, scanning electron microscopy of the dissected devices in the extracorporeal circuit was performed on devices used during four aorto-coronary bypasses and two cardiac valve replacements. Membrane surfaces remained free of major deposits although thrombotic material could still be observed in parts of the oxygenators and the filters. Blood filtration from the cardiotomy reservoir may be more critical as it removes surgical debris and cells injured by suction which appear to enhance thrombus formation within the oxygenator. The return line arterial filter appears more useful as a bubble remover; its value appears much diminished as microemboli do not leave the device in large quantities.     

Impact of bloodstream infections on catheter colonization during extracorporeal membrane oxygenation

There are concerns about secondary extracorporeal membrane oxygenation (ECMO) catheter infections in bacteremic patients. We investigated the association between blood stream infection (BSI) and ECMO catheter colonization. From January 2012 to August 2014, 47 adults who received ECMO support were enrolled. The ECMO catheter tip was cultured at the end of the ECMO procedure. The enrolled patients were classified into two groups according to the presence of BSI during ECMO support and analyzed with respect to ECMO catheter colonization. Of 47 cases, BSI during ECMO was identified in 13 patients (27.7 %). ECMO catheter colonization was identified in 6 (46.2 %) patients in the BSI group and 3 (8.8 %) in the non-BSI group. BSI during ECMO support was independently associated with ECMO catheter colonization [odds ratio (OR) 5.55; 95 % confidence interval (CI) 1.00–30.73; p = 0.049]. The organisms colonizing ECMO catheters in the setting of primary BSI were predominantly Gram-positive cocci and Candida species. Acinetobacter baumannii was the most common colonizing pathogen in the setting of secondary BSI. All the organisms colonizing ECMO catheters were multi-drug resistant organisms, including methicillin-resistant S. aureus, Candida glabrata, and carbapenem-resistant A. baumannii. ECMO catheters may become contaminated with multi-drug resistant pathogens in the presence of BSI. Therefore, ECMO should be applied cautiously in septic patients with bacteremia caused by multi-drug resistant pathogens.     

Use of nafamostat mesilate as an anticoagulant during extracorporeal membrane oxygenation

Although the incidence of bleeding complications during extracorporeal membrane oxygenator (ECMO) support has decreased in various trials, bleeding is still the most fatal complication. We investigated the ideal dosage and efficacy of nafamostat mesilate for use with ECMO in patients with acute cardiac or respiratory failure. We assessed 73 consecutive patients who received ECMO due to acute cardiac or respiratory failure between January 2006 and December 2009. To evaluate the efficacy of nafamostat mesilate, we divided the patients into 2 groups according to the anticoagulants used during ECMO support. All patients of nafamostat mesilate group were male with a mean age of 49.2 yr. Six, 3, 5, and 3 patients were diagnosed with acute myocardial infarction, cardiac arrest, septic shock, and acute respiratory distress syndrome, respectively. The mean dosage of nafamostat mesilate was 0.64 mg/kg/hr, and the mean duration of ECMO was 270.7 hr. The daily volume of transfused packed red blood cells, fresh frozen plasma, and cryoprecipitate and the number of complications related to hemorrhage and thrombosis was lower in the nafamostat mesilate group than in the heparin group. Nafamostat mesilate should be considered as an alternative anticoagulant to heparin to reduce bleeding complications during ECMO.     

Severe hypoxemia during veno-venous extracorporeal membrane oxygenation: exploring the limits of extracorporeal respiratory support

OBJECTIVE:

Veno-venous extracorporeal oxygenation for respiratory support has emerged as a rescue alternative for patients with hypoxemia. However, in some patients with more severe lung injury, extracorporeal support fails to restore arterial oxygenation. Based on four clinical vignettes, the aims of this article were to describe the pathophysiology of this concerning problem and to discuss possibilities for hypoxemia resolution.

METHODS:

Considering the main reasons and rationale for hypoxemia during veno-venous extracorporeal membrane oxygenation, some possible bedside solutions must be considered: 1) optimization of extracorporeal membrane oxygenation blood flow; 2) identification of recirculation and cannula repositioning if necessary; 3) optimization of residual lung function and consideration of blood transfusion; 4) diagnosis of oxygenator dysfunction and consideration of its replacement; and finally 5) optimization of the ratio of extracorporeal membrane oxygenation blood flow to cardiac output, based on the reduction of cardiac output.

CONCLUSION:

Therefore, based on the pathophysiology of hypoxemia during veno-venous extracorporeal oxygenation support, we propose a stepwise approach to help guide specific interventions.     

无泵驱动体外膜肺氧合临床应用进展

对无泵驱动体外膜肺氧合支持疗法的优缺点、并发症和临床应用状况进行总结。临床应用证明无泵驱动体外膜肺氧合疗法应用于呼吸功能衰竭的患者可以降低并发症,提高救治的成功率。     

Insensible water loss during extracorporeal membrane oxygenation: an in vitro study

To measure insensible fluid loss from silicone membrane oxygenators during extracorporeal membrane oxygenation (ECMO), an in vitro system was used. A standard neonatal ECMO circuit (Avecor) was connected to a noncompliant reservoir, which was then primed with normal saline. The experiment was conducted by using two silicone oxygenators (Avecor 0.4 and 0.8 m2), three gas flow rates (0.5, 1.0, and 2.0 L/min) (sweep), and two fluid flow rates (200 and 400 ml/min). Two methods were used to measure the water loss. One method was to replace the water to the noncompliant circuit by using a calibrated burette, and the other method was to collect condensed water after cooling the postmembrane sweep gas to 0 degrees C. The influence of the amount of sweep, fluid flow rate, size of membrane, and inlet and outlet sweep gas temperatures on measured water loss was statistically determined. The amount of water loss correlated with sweep (r2 = 0.81; p<0.00001) but was not related to the fluid flow rate, membrane size, or inlet and outlet sweep gas temperature. The average daily fluid loss measured with replacement and collection methods for each liter of sweep per minute were 72.0+/-12.6 and 62.3+/-10.0 ml, respectively. This information may be applied to clinical practice to accurately manage fluid balance in the sick neonate on ECMO.     

Safe transport of critically ill adult patients on extracorporeal membrane oxygenation support to a regional extracorporeal membrane oxygenation center

Patients with severe cardiac or pulmonary failure who require transport to specialized hospitals currently pose a challenge. Mechanical support in the form of extracorporeal membrane oxygenation (ECMO) may increase the safety of transporting such patients to an institution where they will have access to advanced medical therapy. Over 2.5 years, 17 patients were successfully cannulated and placed on a simplified ECMO circuit at other institutions and transported via ambulance to our hospital. Fourteen patients with acute respiratory distress syndrome (ARDS) were placed on venovenous (VV) ECMO. Two patients with isolated cardiogenic shock and one patient with ARDS were placed on venoarterial (VA) ECMO. The two cardiogenic shock patients were converted to a biventricular assist device shortly after arrival. The median unit-to-unit transport time was 60 minutes (interquartile range 50-92 minutes), and the median distance traveled was 23 miles (interquartile range 17-55 miles). There was no transport-related morbidity or mortality. The median duration of ECMO support was 8 days (interquartile range 4-11 days). Thirteen patients (76%) were successfully decannulated. Ten patients (59%) were weaned from the ventilator, and nine patients (53%) survived up to 3 months and were discharged from the hospital. Critically ill patients with severe ARDS or cardiogenic shock can be safely transported on VV or VA ECMO support to regional ECMO centers. As the indications and demands for ECMO support expand, so will the role for transporting patients on ECMO.     

Subclavian artery cannulation for venoarterial extracorporeal membrane oxygenation

Femoral artery cannulation for venoarterial extracorporeal membrane oxygenation (ECMO) can be associated with ischemic and neurologic complications. The subclavian artery offers an alternative cannulation site, which is helpful in patients with peripheral vascular disease, in those who have sustained pelvic trauma, or when ambulation is anticipated. This is a single-institution review of 20 adults who were placed on venoarterial ECMO using subclavian arterial cannulation over a 2 year period. Technical success with subclavian venoarterial ECMO was 100%. Median ECMO time was 168 hours (2.4-720 hours). Sufficient flows (median 4.24 L/min), oxygenation (median postcannulation PaO2 315 mm Hg), and ventricular unloading confirmed with intraoperative transesophageal echocardiogram were achieved in all patients. Seventy-five percent of patients were decannulated, 50% were extubated, and 45% were discharged. Seven patients (35%) had an entirely upper body ECMO configuration with the internal jugular vein serving as the venous drainage site. Complications included arterial cannula site hematoma and infection, as well as ipsilateral arm swelling. Each required conversion to femoral artery cannulation. There were no ischemic or neurologic complications. Patients with acute cardiopulmonary failure can safely be placed on subclavian venoarterial ECMO for prolonged periods with full flows, adequate oxygenation, and sufficient ventricular unloading.     

Continuous renal replacement therapy in neonates and young infants during extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a therapy that ensures adequate tissue oxygen delivery in patients suffering cardiac and/or respiratory failure that are unresponsive to conventional therapy. During ECMO, it is common to see a decrease in urine output that may be associated with acute renal failure. In this context, continuous renal replacement therapy (CRRT) should be considered. Our aim is to evaluate a pioneer experience in Latin America, related to the use of CRRT in a group of neonatal-pediatric patients during ECMO. We conducted a retrospective review of patients treated with ECMO at our institution between May 2003 and May 2005. Twelve infants were treated with ECMO, six of them also underwent CRRT. The main reasons for CRRT initiation were fluid overload and progressive azotemia. Observed complications were clots in the filter and excessive ultrafiltration. CRRT was successful in fluid management and solute clearance in all patients. Discharge survival rate was 83%, all of them with normal renal function. Concurrent CRRT with ECMO is technically feasible and efficacious in the management of fluid overload and solute clearance. We report the first experience with these therapies in a Latin American neonatal-pediatric ECMO program associated with the Extracorporeal Life Support Organization.     

Disturbed cerebral circulation during opening of the venoarterial bypass bridge in extracorporeal membrane oxygenation

PURPOSE: To describe the effects on cerebral blood flow velocity (CBFV) of intermittent opening of the venoarterial bridge (VA bridge) during venoarterial extracorporeal membrane oxygenation (VA-ECMO). STUDY DESIGN: Prospective study in 22 newborns during VA ECMO. CBFV was measured in the pericallosal artery by Doppler ultrasound. Changes in peak systolic flow velocity (PSV), end diastolic flow velocity (EDV) and time-averaged mean flow velocity (TAM) on day 1, 2, 3, and 5 and at low ECMO flow (50- 150 ml/min) were analyzed (mean percentage+/-standard deviation (t-tests, p<0.05)). Changes >25% were considered relevant. The relationship between changes in CBFV and ECMO flow rate (Pearson correlation, p<0.01) was studied. RESULTS: Opening of the VA bridge resulted in statistically significant and relevant decreases in PSV (35 +/- 18%), EDV (93 +/- 15%) and TAM (68 +/- 13%), persisting during the consecutive days of treatment. Smaller changes in CBFV at low ECMO flow were statistically significant and mostly relevant: PSV (15 +/- 7%), EDV (76 +/- 21%) and TAM (40 +/- 12%). Changes in CBFV were positively correlated to the ECMO flow. CONCLUSION: Use of the VA bridge results in significant and relevant ECMO flow-dependent changes in CBFV, persisting during the treatment. The VA bridge should be used in such a way as to allow regular unclamping to be omitted.     

Aluminum-containing emboli in infants treated with extracorporeal membrane oxygenation

We found fibrin thrombi or thromboemboli at autopsy in 22 of 23 infants with respiratory failure who had been treated with venoarterial extracorporeal membrane oxygenation (ECMO). In addition, distinctive basophilic aluminum-containing emboli were found in 12 of the infants; the distribution of these emboli was similar to that of the thromboemboli, except that an aluminum-containing embolus was found in a lung in only 1 infant. Sixteen infants had pulmonary thrombi or thromboemboli. We also found friable aluminum-containing concretions adhering loosely to the mixing rods of heat exchangers that had been used to warm the blood flowing through the ECMO circuit; such concretions were not present on unused mixing rods. We propose that these aluminum-containing concretions developed as the silicone coating of the heat exchanger wore away and aluminum metal was exposed to warm, oxygenated blood and that fragments of aluminum-containing concretions formed emboli. This hypothesis is supported by the fact that aluminum-containing emboli were generally not present in the lungs, which are bypassed by ECMO. Although infarcts were found in 16 of the 23 infants, we cannot be certain whether any of the infarcts were caused by the aluminum-containing emboli.     

ECMO的临床应用

目的 总结体外膜肺氧合(extracorporeal membrane oxygenation,ECMO)在临床使用中的经验.方法 使用ECMO辅助6例患者(4例使用离心泵辅助,2例使用搏动泵辅助).术后严密监测并发症的发生,积极治疗.结果 6例患者中1例死于肺部感染,1例死于血栓形成,1例死于溶血导致的DIC、3例顺利恢复出院.结论 术前患者的选择,手术的时机和术式,手术后患者的管理,ECMO的选择是决定使用ECMO能否成功的关键.     

Interhospital transport of ARDS patients on extracorporeal membrane oxygenation

Journal of Artificial Organs - Veno-venous extracorporeal membrane oxygenation (ECMO) can be a lifesaving therapy for patients with severe acute respiratory distress syndrome (ARDS). ECMO is a...     

Neonatal respiratory extracorporeal membrane oxygenation (ECMO) referrals

Extracorporeal membrane oxygenation (ECMO) is a complex technique for providing life support in neonatal respiratory failure. T UK Collaborative ECMO trial demonstrated cost-effectiveness and substantial improvements in neurological morbidity and mortality. Currently, infants requiring ECMO in Ireland are referred to one of various centres in the UK and Scandinavia. We aimed to review the number of infants referred from Ireland for respiratory ECMO. All infants with a non-cardiac condition referred from Ireland for ECMO were reviewed for diagnosis and outcomes. Eleven infants required ECMO between June 2006 and January 2009 and were referred to the Scandinavian team for ECMO transport although one infant improved and did not require ECMO following the arrival of the team. Four infants died: one infant died prior to arrival of the ECMO team, 3 infants had fatal diagnoses and one infant with congenital diaphragmatic hernia received pre-op ECMO. The median (inter-quartile range) gestational age was 39.7 (38.3-40.7) weeks and birth weight of 3.7 (3.2-4.0) kg. The median age at the decision to transfer for ECMO was 13h (4-123) and the team arrived at 23 h (12-132). All infants had a normal cranial ultrasound and echo prior to ECMO and 2 infants had an abnormal MRI post-ECMO. The time on ECMO was 9 days (3-17) and total length of hospital stay was 32 d (23-36). There were no pre-ECMO clinical or biochemical     

Ease of conversion from venovenous extracorporeal membrane oxygenation to cardiopulmonary bypass and venoarterial extracorporeal membrane oxygenation with a bicaval dual lumen catheter

Extracorporeal circulatory support revolutionized the field of cardiothoracic surgery, initially in the form of cardiopulmonary bypass (CPB) and then in its modified form, extracorporeal membrane oxygenation (ECMO). Although initial cannulation techniques involved open intrathoracic approaches, the increased prevalence of reoperative sternotomies and the emergence of minimally invasive surgery encouraged the development of peripheral cannulation methods and configurations. The Avalon Elite Bicaval Dual Lumen catheter (Avalon Laboratories, LLC, CA) can be placed in the right internal jugular vein to provide venovenous (VV) ECMO. However, some patients on VV ECMO then develop compromised cardiac performance. We describe two ways in which the Avalon Elite was used, first for complete venous drainage through a single peripheral site for CPB and in the other to convert a patient on VV ECMO to axillary artery venoarterial (VA) ECMO.     

Rescue extracorporeal membrane oxygenation for massive anterior mediastinal masses

Journal of Artificial Organs - The management of massive anterior mediastinal masses (AMM) is challenging. With the burgeoning role of extracorporeal membrane oxygenation support (ECMO) beyond the...     

Usefulness of surveillance cultures in neonatal extracorporeal membrane oxygenation

Sepsis is difficult to identify in patients treated with extracorporeal membrane oxygenation (ECMO). This study evaluates the usefulness of surveillance cultures obtained during ECMO. We retrospectively reviewed the records of 187 patients from four ECMO centers with birth weights 1,574 to 4,900 gm and gestational ages 33-43 weeks, over a 4 year interval. Most patients had surveillance blood cultures daily, and tracheal aspirates and urine culture every other day. Charts were reviewed for culture results before, during, and for the 7 days after ECMO, and clinical response to the culture results. A total of 2,423 cultures were obtained during 1,487 days of ECMO, of which 155 were positive (6.4%): 13 of 1,370 blood cultures (0.9%), 137 of 850 tracheal aspirate cultures (16%), and 5 of 203 urine cultures (2.3%). After 72 hours, tracheal aspirate cultures became positive with nosocomial organisms in 33 of 131 patients. None of 153 bacterial urine cultures were positive, and only one of 34 viral urine cultures were positive (CMV). We conclude that routine daily blood cultures are not useful in neonatal ECMO. Tracheal aspirate cultures may be helpful in the management of antibiotic therapy in patients on ECMO for more than 5 days. Routine bacterial urine cultures did not provide useful information.