Quantification of recirculation by thermodilution during venovenous extracorporeal membrane oxygenation

PURPOSE: The aim of this study was to determine whether recirculation could be quantified by a thermodilution technique during venovenous (VV) extracorporeal membrane oxygenation (ECMO) in a rabbit model. METHODS: Five New Zealand white rabbits, mean weight, 4.5 (range, 3.7 to 5.7) kg, were anesthetized, instrumented, cannulated with a double-lumen catheter, and placed on VV ECMO. Serial injections of ice-cold saline were performed at the arterial arm of the circuit, and the resultant temperature change at various pump flows was measured at the venous arm of the circuit using a thermistor-tipped catheter and a cardiac output computer. Results were compared with the respective 100% recirculation measured with all the circuit flow passing through the bridge. RESULTS: Using linear regression, recirculation percentage could be calculated as: 19 + 0.1 x pump flow (R2 = 0.81, P < .005). Recirculation correlated positively with pump flow. Variability between results at each flow was less than 10%. CONCLUSIONS: Recirculation can be quantified during VV ECMO by measuring the change in temperature in the venous arm using a cardiac output computer after injection of a known quantity of ice-cold saline in the arterial side of the circuit. The effect of interventions to reduce recirculation can be assessed conveniently and reliably.     

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.     

Validation of haemodialysis recirculation and access blood flow measured by thermodilution.

BACKGROUND: Recirculation (R) and access blood flow (Qac) measurements are considered useful indicators of adequate delivery of haemodialysis. It was the purpose of this study to compare measurements of R and Qac obtained by two different techniques which are based on the same principle of indicator dilution, but which differ because of the characteristics of the injection and detection of the different indicators used. METHODS: Recirculation measured by a thermal dilution technique using temperature sensors (BTM, Fresenius Medical Care) was compared with recirculation measured by a validated saline dilution technique using ultrasonic transducers placed on arterial and venous segments of the extracorporeal circulation (HDM, Transonic Systems, Inc.). Calculated access flows were compared by Bland Altman analysis. Data are given as mean +/- SD. RESULTS: A total of 104 measurements obtained in 52 treatments (17 patients, 18 accesses) were compared. Recirculation measured with correct placement of blood lines and corrected for the effect of cardiopulmonary recirculation using the 'double recirculation technique' was -0.02 +/- 0.14% by the BTM technique and not different from the 0% measured by the HDM technique. Recirculation measured with reversed placement of blood lines and corrected for the effect of cardiopulmonary recirculation was 19.66 +/- 10.77% measured by the BTM technique compared with 20.87 +/- 11.64% measured by the HDM technique. The difference between techniques was small (-1.21 +/- 2.44%) albeit significant. Access flow calculated from BTM recirculation was 1328 +/- 627 ml/min compared with 1390 +/- 657 ml/min calculated by the HDM technique. There was no bias between techniques. CONCLUSION: BTM thermodilution yields results which are consistent with the HDM ultrasound dilution technique with regard to both recirculation and access flow measurement.     

Venovenous Extracorporeal Membrane Oxygenation (ECMO) Using a Double-Lumen Cannula

Extracorporeal membrane oxygenation (ECMO) can support neonates with severe respiratory failure. Currently, the most common application of ECMO requires venoarterial access. Venovenous (VV) ECMO is desirable to avoid common carotid artery ligation. However, the best technique of venous access for VV ECMO is not established. Using a single cannula with a double-lumen (DLC) in the right atrium for simultaneous drainage and infusion of blood, VV ECMO provided total respiratory support for six apneic puppies for 3 h each. Mean systemic arterial oxygenation was lower with DLC VV (50 torr) compared to VA ECMO (247 torr), but a physiologic pH (mean 7.34) was maintained on DLC VV bypass. Higher mean bypass flow was required on DLC VV (124 ml/kg/min) compared to VA flow (101 ml/kg/min) because of recirculation of oxygenated blood. The position of the DLC in the right atrium needed to be closely monitored. Hemorrhage was noted in the myocardium after use of DLC VV ECMO.     

A complication of ECMO cannula placement resulting in hemodynamic and oxygenation alterations: A case report

Veno-veno extracorporeal membrane oxygenation (VV ECMO) is used as a bridge to recovery in acute respiratory distress syndrome (ARDS) patients who have reversible lung failure. We present a complication of ECMO cannula placement/position resulting in hemodynamic and oxygenation alterations. These demonstrate principles related to the interaction of the VV ECMO circuit and patient cardio-pulmonary physiology. Consideration and comprehension of pulmonary shunt fraction, ECMO cannula recirculation ratio and ECMO blood flow to cardiac output (CO) ratio are central to continuous assessment and diagnosis of cardio-pulmonary changes encountered during management of VV ECMO.     

Hemodynamic evaluation of the Avalon Elite bi-caval dual lumen cannulae

In previous studies, we have evaluated the hemodynamic properties of selected oxygenators, pumps (centrifugal and roller), and single lumen cannulae. Because the dual lumen cannulae are widely used in veno-venous extracorporeal life support (ECLS) and are receiving popularity due to their advantages over the single lumen cannulae, we evaluated the flow ranges and pressure drops of three different sizes of Avalon Elite dual lumen cannulae (13Fr, 16Fr, and 19Fr) in a simulated neonatal ECLS circuit primed with human blood. The experimental ECLS circuit was composed of a RotaFlow centrifugal pump, a Capiox BabyRX05 oxygenator, 3 ft of 1/4-in venous and arterial line tubing, an Avalon Elite dual lumen cannula, and a soft reservoir as a pseudo-right atrium. All experiments were conducted at 37°C using an HCU 30 heater-cooling unit and with human blood at a hematocrit of 36%. The blood pressure in the pseudo-right atrium was continuously monitored and maintained at 4-5 mm Hg. For each cannula, pump flow rates and pressures at both the arterial and venous sides were recorded at revolutions per minute (RPMs) from 1750 to 3750 in 250 intervals. For each RPM, six data sets were recorded for a total of 162 data sets. The total volume of the system was 300 mL. The flow range for the 13Fr, 16Fr, and 19Fr cannulae were from 228 to 762 mL/min, 478 to 1254 mL/min, and 635 to 1754 mL/min, respectively. The pressure drops at the arterial side were higher than the venous side at all tested conditions except at 1750 rpm for the 19Fr cannula. The results of this study showed the flow ranges and the pressure drops of three different sized dual lumen cannulae using human blood, which is more applicable in clinical settings compared with evaluations using water.     

Bedside exclusion of clinically significant recirculation volume during venovenous ECMO using conventional blood gas analyses

STUDY OBJECTIVE: To investigate prospectively whether blood gas samples drawn from extracorporeal membrane oxygenation (ECMO) cannulae help to exclude at least clinically significant recirculation volumes in patients with acute respiratory failure. DESIGN: Feasibility study. SETTING: Intensive care unit at a university-affiliated hospital. PATIENTS: Ten consecutive adult patients suffering from severe respiratory failure and undergoing ECMO. INTERVENTIONS: The drawing (venous) ECMO cannula was placed into the inferior vena cava via a femoral vein, and the oxygenated blood was returned via the right subclavian vein by supraclavicular access directly into the right atrium. Blood gas samples were obtained from both cannulae. MEASUREMENTS AND MAIN RESULTS: The median arterial oxygen tension (PaO(2)) obtained from the arterial cannula was 537 mmHg (range, 366 to 625 mmHg), the median mixed venous oxygen tension (PvO(2)) drawn from the venous cannula was 42 mmHg (range, 25 to 54 mmHg), which was less than 10% of that observed in the arterial cannula, and also within the physiologic range of PvO(2). The ECMO flow necessary to maintain patients' oxygen saturation above 90% (4.1 L/min; range, 1.95 to 5.8 L/min) was significantly lower than the patients' cardiac output (CO; 6.2 L/min; range, 4.1 to 7.9 L/min; p < 0.001). CONSLUSIONS; We recommend obtaining blood gas samples-immediately after initiation of ECMO-from both cannulae. A PvO(2) within physiologic range and below 10% of PaO(2) rules out any clinically relevant recirculation volume.     

Venovenous extracorporeal membrane oxygenation in neonatal respiratory failure: does routine, cephalad jugular drainage improve outcome?

Background/purpose

Extracorporeal membrane oxygenation (ECMO), may be life saving for infants with severe respiratory failure, and when possible, veno-venous bypass through a jugular double lumen cannula, can be expected to provide satisfactory support for most patients. Some ECMO centers favor routine placement of a cephalad jugular cannula for the theoretical benefits of augmented (desaturated) venous return, reduction of atrial recirculation, and cerebral venous decompression. The purpose of this study was to querie the ELSO registry for patients who had undergone VV-ECMO and compare outcomes for patients with a double lumen cannula only (VVDL), with those who had both a double lumen and cephalad jugular cannula (VVDL + V).

Methods

With institutional review board (IRB) approval, the Extracorporeal Life Support Organization (ELSO) registry (Ann Arbor, MI) was queried from January 1, 1989 to December 31, 2001, and all “neonatal respiratory” patients undergoing VV-ECMO via either the VVDL or VVDL + V modes were identified. Group comparisons by age, diagnosis, hours on bypass, mean flow rates (Q) at 4 and 24 hours, mean airway pressures (MAP) at initiation and at 24 hours of bypass, complications (including neurologic and cannula-specific), need for conversion to veno-arterial (VA) ECMO, and survival were performed. A similar analysis was performed on a congenital diaphragmatic hernia (CDH) patient subgroup. Student’s t tests were used to compare means between groups, with P values of less than .05 considered significant.

Results

The querie generated a total of 2,471 patients: 2,379 (96.3%) VVDL, and 92 (3.7%) VVDL + V. The groups were comparable with the only significant differences being a higher mean airway pressure at 24 hours of bypass and a more frequent use of inotropes during extracorporeal life support (ECLS) in the VVDL + V group. Comparison of a CDH patient subset (280 from the VVDL group and 25 from the VVDL + V group) showed the following significant differences: more frequent use of inotropes, higher MAP at 24 hours, and higher mean flow rates at 4 and 24 hours, all in the VVDL + V group. Patient outcomes, including survival, complications, and rates of conversion to VA bypass were comparable between like groups.

Conclusions

The theoretical benefits of routine placement of a cephalad jugular cannula during VV-ECMO via a jugular double lumen cannula are not substantiated by critical analysis of ELSO data.     

Veno-venous ECMO for the respiratory failure after coronary artery bypass grafting

We encountered a 60-year-old man with severe respiratory failure after CABG. The patient received veno-venous extracorporeal membrane oxygenation (ECMO) in which blood was drained from the right atrium through a cannula and was returned via a cannula in the left femoral vein. During ECMO, the flow rate was 2.8-3.0 l/min (about 40 ml/kg/min) and the assist was needed for 5 years. Veno-venous ECMO is a simple and effective therapy for acute respiratory failure unresponsive to conventional treatment.     

Sensitivity and specificity of the thermodilution technique in detection of access recirculation

BACKGROUND/AIM: Recirculation measured by thermodilution includes effects caused by access and cardiopulmonary recirculation. The aims of this study were to illustrate the accuracy of thermodilution in measurement of hemodialysis recirculation and also to identify a sensitive and specific threshold to detect access recirculation. METHODS: 110 studies were performed in 19 patients. Recirculation obtained directly by the blood temperature monitor (BTM) was compared to that calculated from access blood flow, pump blood flow, and cardiac output determined by ultrasound dilution using the hemodialysis monitor (HDM). RESULTS: A highly significant linear correlation was obtained between repeated BTM recirculation measurements (R(BTM, 2) = 0.99.R(BTM, 1) - 0.22%, r(2) = 0.99). There were no significant differences between repeated BTM recirculation measurements with correct placement (11.4+/-7.1 vs. 10.9+/-7.4%, p = NS) or reversed placement (30.0+/-15.6 vs. 30.2 +/-15.9%, p = NS) of blood lines. A strong linear relationship was obtained between the recirculation determined by thermodilution and the recirculation calculated from HDM measurements (R(calc) = 0.98. R(BTM) - 1.49%, r(2) = 0.95). The mean recirculation obtained by BTM was not significantly different from the recirculation calculated by HDM with correct placement (9.5+/- 2.2 vs. 8.6+/-2.5%, p = NS) or with reversed placement (25.4+/-7.8 vs. 23.8+/-7.7%, p = NS) of blood lines. When a recirculation greater than 15% measured by the BTM was considered as the threshold at which true access recirculation occurred, sensitivity and specificity of the thermodilution method to detect access recirculation were 93 and 98%, respectively. CONCLUSIONS: Recirculation measurements made by the BTM are accurate and precise. Even though BTM thermodilution includes effects of cardiopulmonary recirculation, so that low levels of access recirculation might not be detected, a BTM recirculation >15% represents a highly significant access recirculation.     

Haemodialysis recirculation detected by the three-sample method is an artefact

The efficiency of haemodialysis may be limited by recirculationof blood between venous and arterial needles. Recirculationcan be detected directly using a saline dilution method butis most commonly calculated from the urea concentrations ofsimultaneous samples from venous and arterial lines and a peripheralvein (three-sample method). The methods detect markedly differentrates of recirculation in similar study populations. To investigatethe possibility that the methods detect different phenomena,we performed both tests on 16 haemodialysis patients at variousextracorporeal blood flow rates (Qb). The saline dilution methodshowed no recirculation in any of the patients, whereas thethree-sample method indicated recirculation in all patients.The three-sample method indicated a mean recirculation fractionof 12.5% (SD 6.1) and was not influenced by changing Qb, suggestingthat it was not detecting fistula recirculation. The three-samplemethod detects a solute concentration difference between arterialblood and peripheral blood during dialysis. There appears tobe a disequilibrium between a central pool, represented by thearterial sample, and a poorly perfused peripheral pool, relativelyisolated from the dialysis process, represented by the peripheralvenous sample. The three-sample method for detecting recirculationshould be abandoned.     

Venovenous extracorporeal membrane oxygenation in neonates with respiratory failure

Venoarterial (VA) extracorporeal membrane oxygenation (ECMO) has been successful in support of neonates with respiratory failure but requires right common carotid artery ligation. While no short-term neurologic complications have resulted from neonatal carotid ligation, late complications may occur. For both VA ECMO and venovenous (VV) ECMO, blood is drained from the right atrium via a right internal jugular cannula, oxygenated by a membrane lung, and returned to the patient. VV ECMO spares the carotid by perfusing the oxygenated blood into a vein. VV ECMO gave total respiratory support to three neonates with respiratory failure and each infant survived. In comparison with three similar VA ECMO patients, the VV patients required higher ECMO circuit flow rates and had lower systemic arterial Po2s. Length of time on ECMO, length of hospital stay, and neurologic outcome were similar in the VV and VA patients. Differences among the patients were related to their primary disease rather than to the mode of ECMO support. The VV patients had cannulation of the femoral vein for perfusion of oxygenated blood. Late complications may occur from femoral vein ligation as well as from carotid ligation so long-term follow-up is needed to assess these two ECMO techniques.     

Venovenous perfusion in ECMO for newborn respiratory insufficiency. A clinical comparison with venoarterial perfusion.

Venoarterial (VA) extracorporeal membrane oxygenation (ECMO) has been successful in the treatment of newborns less than 1 week of age and greater than 2000 gm birthweight with respiratory failure resistant to current medical and surgical management. While VA ECMO supports the heart as well as the lungs, it has the disadvantage of requiring carotid artery ligation and the possibility of perfusing air bubbles or particles into the arterial tree. We have treated 11 newborns with respiratory failure with venovenous (VV) ECMO returning the oxygenated blood to a cannula in the distal iliac vein. We compared these patients with 16 patients treated during the same period of time with VA ECMO. Three of the 11 VV patients required conversion to VA ECMO because of inadequate oxygenation and unstable hemodynamic situations. Ten of the 11 VV patients survived. Eleven of the 16 VA patients survived. The better survival in these patients treated with VV ECMO is attributed to their more favorable initial condition compared to patients treated with VA ECMO. The disadvantages of VV ECMO include a longer operative time to place the cannulas, groin wound problems, and persistent leg swelling along with the necessity to convert some patients to VA ECMO. Although this experience demonstrates that newborns with severe respiratory failure can be supported with VV ECMO, the complications and lack of practical advantages over VA lead us to recommend VA ECMO for routine clinical use at present.     

Extracorporeal membrane oxygenation as a platform for recovery: a case report of a child with pulmonary hemorrhage, refractory hypoxemic respiratory failure, and new onset goodpasture syndrome

We report a case of a 9-year-old female with acute pulmonary hemorrhage and refractory hypoxemic respiratory failure secondary to Goodpasture syndrome (GS). After failing treatment with high frequency oscillatory ventilation and inhaled nitric oxide, she was successfully managed with venovenous extracorporeal membrane oxygenation (VV ECMO). The patient's weight at the time of cannulation was 31 kg. A 19 French 18 cm (arterial) Biomedicus cannula was inserted in the right internal jugular vein and used as the drain. A 17 French 50 cm (venous) Biomedicus cannula was inserted in the right femoral vein and used as the return. Then the patient was anticoagulated with 100 units/kg of intravenous heparin and the circuit was primed with one unit of packed red blood cells. VV ECMO was performed with an SIII Sorin roller head pump with integrated servo regulator and a Quadrox D Bioline coated oxygenator. Despite systemic anticoagulation with heparin, the patient's pulmonary hemorrhage resolved. Extracorporeal membrane oxygenation served as a platform through which we were able to provide renal replacement therapy and plasmapheresis. The patient was successfully discharged home with normal pulmonary function.     

All currently used measurements of recirculation in blood access by chemical methods are flawed due to intradialytic disequilibrium or recirculation at low flow

Blood flows and recirculations with standard and reversed direction of lines were measured by chemical (urea and creatinine) and ultrasound dilution (saline) methods in 47 chronic hemodialysis patients. Thirty-seven patients had 47 dual-lumen, central vein (CV) catheters: 32 were PermCath (Quinton Instruments Company, Seattle, WA), 6 were Access Cath (MEDCOMP, Harleysville, PA), 3 were Soft Cell PC (Vas Cath, Mississauga, Ontario, Canada) and 6 were SNIJ (experimental catheters). Three of these last catheters had the tip staggered 7 mm, and three had flush tips; PermCath, Access Cath, and Soft Cell PC catheters have the tips staggered 23 to 25 mm. Forty-six catheters were implanted into the superior vena cava/right atrium, and one catheter was implanted through the left saphenous vein into the left iliac vein. The catheters were studied 1 to 31 months after implantation (median, 3.0 months). Ten patients with arteriovenous (AV) graft access were also studied. The stop-flow method was used in catheter dialysis, and the slow-flow method was used to calculate recirculations in AV access dialysis with samples for systemic blood concentrations taken from arterial line both before and after samples from the arterial and venous lines. At 500 mL/min pump speed, actual blood flow was 436+/-18 mL/min (mean+/-SD; range, 407 to 464 mL/min) with standard direction of catheter lines. At 500 mL/min pump speed, the arterial chamber pressure was -330+/-48 mm Hg (mean+/-SD; range, -380 to -225 mm Hg, and the venous chamber pressure was 259+/-48 mm Hg (mean+/-SD; range, 140 to 310 mm Hg). Arterial chamber pressure was less negative, and venous chamber pressure was less positive with SNIJ catheters, which had larger internal diameter (2.1 mm) compared with the other catheters (2.0 mm). Recirculation varied with the catheter design and the location of the catheter tip. In the catheters with tip staggered more than 20 mm and with standard line connection at pump speeds of 50 mL/min and 500 mL/min, recirculations were approximately 1 % and 5%, respectively, when measured by the chemical method. In the same catheters with reversed lines, the recirculations were approximately 5% and 27%, respectively. Inflow failure catheters with reversed lines had similar recirculation values to those of well-functioning catheters with reversed lines. In catheters with tips staggered 7 mm, and with standard connection of lines, recirculations were approximately 3% and 8%, respectively, at pump speeds of 50 and 500 mL/min. With reversed lines, at the same pump speeds, the values were 7% and 12%, respectively. In flush-tip catheters, the recirculation was higher at a 50 mL/min pump speed (approximately 17%) than at a pump speed of 500 mL/min (approximately 13%). The ultrasound dilution method usually gave lower values than the chemical methods, most likely because of overestimation of recirculation by chemical methods. At least triplicate measurements are needed because single measurements by the ultrasound dilution method are associated with substantial variation. We conclude that both currently used methods (stop flow and slow flow) of taking systemic samples for measurements of recirculation by chemical methods are flawed because of disequilibrium and recirculation at low flow.     

Hemodynamic Evaluation of Avalon Elite Bi‐Caval Dual Lumen Cannulas and Femoral Arterial Cannulas

Translational research is a useful tool to provide scientific evidence for cannula selection during extracorporeal life support (ECLS). The objective of this study was to evaluate four Avalon Elite bi‐caval dual lumen cannulas and nine femoral arterial cannulas in terms of flow range, circuit pressure, pressure drop, and hemodynamic energy transmission in a simulated adult ECLS model. A veno‐venous ECLS circuit was used to evaluate four Avalon Elite bi‐caval dual lumen cannulas (20, 23, 27, and 31 Fr), and a veno‐arterial ECLS circuit was used to evaluate nine femoral arterial cannulas (15, 17, 19, 21, and 23 Fr). The two circuits included a Rotaflow centrifugal pump, a Quadrox‐D adult oxygenator, and 3/8 in ID tubing for arterial and venous lines. The circuits were primed with lactated Ringer’s solution and packed human red blood cells (hematocrit 40%). Trials were conducted at rotational speeds from 1000 to 5000 RPM (250 rpm increments) for each Avalon cannula, and at different flow rates (0.5–7 L/min) for each femoral arterial cannula. Real‐time pressure and flow data were recorded for analysis. Small caliber cannulas created higher circuit pressures, higher pressure drops and higher M‐numbers compared with large ones. The inflow side of Avalon dual lumen cannula had a significantly higher pressure drop than the outflow side (inflow vs. outflow: 20 Fr‐100.2 vs. 49.2 mm Hg at 1.1 L/min, 23 Fr‐93.7 vs. 41.4 mm Hg at 1.6 L/min, 27 Fr‐102.3 vs. 42.8 mm Hg at 2.6 L/min, 31 Fr‐98.1 vs. 44.7 mm Hg at 3.8 L/min). There was more hemodynamic energy lost in the veno‐arterial ECLS circuit using small cannulas compared to larger ones (17 Fr vs. 19 Fr vs. 21 Fr at 4 L/min—Medtronic: 71.0 vs. 64.8 vs. 60.9%; Maquet: 71.4 vs. 65.6 vs. 62.0%). Medtronic femoral arterial cannulas had lower pressure drops (Medtronic vs. Maquet at 4 L/min: 17 Fr‐121.7 vs. 125.0 mm Hg, 19 Fr‐71.2 vs. 73.7 mm Hg, 21 Fr‐42.9 vs. 47.4 mm Hg) and hemodynamic energy losses (Medtronic vs. Maquet at 4 L/min: 17 Fr‐43.6 vs. 44.4%, 19 Fr‐31.0 vs. 31.4%, 21 Fr‐20.8 vs. 22.4%) at high flow rates when compared with the Maquet cannulae. The results for this study provided valuable hemodynamic characteristics of all evaluated adult cannulas with human blood in order to guide ECLS cannula selection in clinical practice. Use of larger cannulas are suggested for VV‐ and VA‐ECLS.     

Severe thrombotic and bleeding complications in a baby with heterozygous factor V Leiden and acquired von Willebrand disease on ECMO

We aim to present the case of a 5-week-old girl with severe respiratory failure placed on veno-venous extracorporeal membrane oxygenation (ECMO) that was then switched to veno-arterial ECMO. She required up to 60 units/kg/hr of heparin to keep her heparin level within the target range at .3-.7 units/mL. During the ECMO course, substantial thrombus formation was observed within the venous site of the ECMO cannula, which led to two circuit changes on ECMO day 9 and day 20. On ECMO day 15, she was noticed to have purpuric lesions on her chest and her right hand with no obvious arterial or venous clot detected by Doppler ultrasound. She was also noted to have remarkable hemolysis as the plasma free hemoglobin levels were substantially elevated up to 700 mg/dL. She was noted to have continuous oozing from the catheter insertion sites despite adequate underlying coagulation status. Her subsequent platelet function analysis, the thromboelastography, and thromboelastography platelet mapping suggested substantial platelet dysfunction. Her von Willebrand panel revealed absence of high molecular weight multimers. Further coagulation workup was prompted which revealed heterozygosity for factor V Leiden. The patient developed severe pulmonary hemorrhages and ECMO was discontinued on day 40.     

Venovenous extracorporeal membrane oxygenation in neonatal systemic artery-to-pulmonary artery shunt operations using a double lumen catheter

The right atrium of the neonate may be too small for direct insertion of 2 venous catheters during intraoperative life support. We inserted a double lumen catheter into the right atrium, and venovenous (V-V) extracorporeal membrane oxygenation (ECMO) was instituted. The patient's arterial oxygen saturation was maintained at 70% to 90%, and hemodynamic stability was obtained during V-V ECMO. V-V ECMO using a double lumen catheter can be easily established in a small neonate, and is an effective support technique for untolerable hypoxemia during systemic-to-pulmonary artery shunt operations.     

A Centrifugal Pump Driven Tidal Flow Extracorporeal Membrane Oxygenation System Tested with Neonatal Mock Circulation

In 1993, Chevalier published his experiences with tidal flow venovenous extracorporeal membrane oxygenation (ECMO) featuring a single lumen cannula, non-occlusive roller pump, and alternating clamps. Using a neonatal mock circulation (NMC), which enables different hemodynamic states for neonatal ECMO research, the tested hypothesis was that it is possible to create a centrifugal pump driven tidal flow neonatal venovenous ECMO system. Additionally, the resulting hemodynamic effects in a condition of circulatory impairment were investigated. The ECMO circuit tested was assembled using a pediatric centrifugal pump head, a distensible reservoir, and a rotary clamp separating drainage from the injection phase. Using the NMC, end tidal volumes, mock circulation flow, and arterial and venous pressures were measured at different pump speeds after the drainage and injection phases. Effective venovenous ECMO flow (evvEF) was calculated. Mock circulation baseline values (ECMO clamped) were compared to values during tidal flow ECMO. At 3,000 rpm, a centrifugal pump speed of 75 ml/kg/min evvEF was reached, and it increased with higher pump speeds. At this point, the end tidal mock circulation flow (representing cardiac output) after drainage differed significantly from that during the injection phase (p < 0.01) but not from the baseline value. The end tidal arterial and venous pressures after the drainage phase were found to be significantly decreased compared to the baselines (p < 0.01). In conclusion, a centrifugal pump driven tidal flow venovenous ECMO system can be created enabling sufficient tidal volumes. Tested in the described NMC simulating posthypoxic circulatory impairment, significant hemodynamic effects could be demonstrated. Animal experiments for confirmation are necessary.     

Extracorporeal membrane oxygenation cannulation trends for pediatric respiratory failure and central nervous system injury

BackgroundGuidelines regarding arterial cannula site and cannula site-specific risks of central nervous system (CNS) injury for pediatric patients requiring extracorporeal membrane oxygenation (ECMO) support are lacking. We reviewed cannulation trends for pediatric respiratory failure and evaluated CNS complication rates by cannulation site and mode of support.MethodsThe Extracorporeal Life Support Organization (ELSO) registry was queried for all pediatric respiratory failure patients <18 years treated from 1993-2007. The primary outcome was radiographic evidence of CNS injury.ResultsVenoarterial (VA) support was used in 62% of 2617 ECMO runs. The carotid artery was used in 93% of VA patients. Femoral artery use increased in patients >5 years of age and >20 kg. Venovenous (VV) ECMO was used in >50% of children >10 years. No significant difference was identified in CNS injury between carotid and femoral cannulation in any age group but the femoral group was small (4.4%). VA support was independently associated with increased odds of CNS injury compared to VV cannulation (OR, 1.6).ConclusionVA ECMO is the most common mode of support in pediatric respiratory failure patients. Although no significant difference in CNS injury was noted between carotid and femoral artery cannulation, the odds of injury were significantly higher than VV support.