Differential hypoxemia and the clinical significance of venous drainage position during extracorporeal membrane oxygenation.

Differential hypoxemia (DH) has been recognized as a clinical problem during veno-arterial extracorporeal membrane oxygenation (VA ECMO) although its features and consequences have not been fully elucidated.This single center retrospective study aimed to investigate the clinical characteristics of patients manifesting DH as well as the impact of repositioning the drainage point from the inferior vena cava (IVC) to the superior vena cava to alleviate DH.All patients (>15 years) commenced on VA ECMO at our center between 2009 and 2020 were screened. Of 472 eligible patients seven were identified with severe DH. All patients had the drainage cannula tip in the IVC or at the junction between the IVC and right atrium.The mean peripheral capillary saturation increased from 54 (±6.6) to 86 (±6.6) %, (p = <0.001) after repositioning of the cannula. Pre-oxygenator saturation increased from 62 (±8.9) % prior to adjustment to 74 (±3.7) %, (p = 0.016) after repositioning. Plasma lactate tended to decrease within 24 h after adjustment. Five patients (71%) survived ECMO treatment, to discharge from hospital, and were alive at 1-year follow-up.Although DH has been described in several studies, the condition has not been investigated in a clinical setting comparing the effect on upper body saturation before and after repositioning of the drainage cannula. This study shows that moving the drainage zone into the upper part of the body has a marked positive effect on upper body saturation in patients with DH.

Extracorporeal Membrane Oxygenation for Septic Shock.

OBJECTIVES: Septic shock carries a high mortality risk. Studies have indicated that patients with septic shock may benefit from extracorporeal membrane oxygenation. In most studies, patients exhibited shock due to myocardial dysfunction rather than distributive/vasoplegic shock. One proposed theory is that venoarterial extracorporeal membrane oxygenation alleviates a failing myocardial function. DESIGN: Retrospective observational study. SETTING: Single-center, high-volume extracorporeal membrane oxygenation unit. PATIENTS: All patients treated for septic shock between 2012 and 2017 with an age greater than 18 years old, fulfilling septic shock criteria according to "Sepsis-3" at acceptance for extracorporeal membrane oxygenation, presence of cardiocirculatory failure requiring a support equivalent to a Vasoactive Inotropic Score greater than 50 to reach a mean arterial pressure greater than 65 mm Hg despite adequate fluid resuscitation, were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Thirty-seven patients, mean age 54.7 years old, were included. Median Simplified Acute Physiology Score-3 score was 86 and Sequential Organ Failure Assessment 16. Twenty-seven patients were submitted to venoarterial and 10 patients to venovenous extracorporeal membrane oxygenation. Hospital survival was 90% for septic shock with left ventricular failure and 64.7% in patients with distributive shock. At long-term follow-up at 46.1 months, total survival was 59.5%. Commencement of venovenous extracorporeal membrane oxygenation and more organ failures at admission showed a less favorable outcome in terms of hospital and long-term survival. CONCLUSIONS: The current results add not only to the growing evidence of the benefit of venoarterial extracorporeal membrane oxygenation for septic cardiomyopathy but also indicate improved hospital survival in distributive septic shock.

Long-term pulmonary function and quality of life in adults after extracorporeal membrane oxygenation for respiratory failure.

BACKGROUND: There is a significant long-term burden on survivors after acute respiratory distress syndrome, even 5 years after discharge. This is not well investigated in patients treated with extracorporeal membrane oxygenation. The objective of this study was to describe very-long-term (⩾3 years) disability in lung function and morphology, quality of life, mood disorders, walking capacity, and return to work status in extracorporeal membrane oxygenation survivors. METHODS: Single-center retrospective cohort study on long-term survivors treated with extracorporeal membrane oxygenation for respiratory failure between 1995 and 2010 at a tertiary referral center in Sweden. Eligible patients were approached, and those who consented were interviewed and investigated during a day at the hospital. RESULTS: A total of 38 patients were investigated with a median follow-up time of 9.0 years. Quality of life was reduced in several Short form 36 (SF-36) subscales and all domains of the St George's Respiratory Questionnaire, similar to previous studies in conventionally managed acute respiratory distress syndrome survivors. A reduced diffusion capacity of carbon monoxide was seen in 47% of patients, and some degree of residual lung parenchymal pathology was seen in 82%. Parenchymal pathology correlated with reductions in quality of life and diffusion capacity. Symptoms of anxiety and depression were seen in 22% and 14%, respectively. CONCLUSION: A significant long-term burden remains even 3-17 years after extracorporeal membrane oxygenation treatment, similar to conventionally managed acute respiratory distress syndrome survivors. Future prospective studies are needed to elucidate risk factors for these sequelae.

Long-Term Cognitive Outcome and Brain Imaging in Adults After Extracorporeal Membrane Oxygenation.

OBJECTIVES: To investigate the presence of cognitive dysfunction and brain lesions in long-term survivors after treatment with extracorporeal membrane oxygenation for severe respiratory failure, and to see whether patients with prolonged hypoxemia were at increased risk. DESIGN: A single-center retrospective cohort study. SETTING: Tertiary referral center for extracorporeal membrane oxygenation in Sweden. PATIENTS: Long-term survivors treated between 1995 and July 2009. Seven patients from a previously published study investigated with a similar protocol were included. INTERVENTIONS: Brain imaging, neurocognitive testing, interview. MEASUREMENTS AND MAIN RESULTS: Thirty-eight patients (i.e., n = 31 + 7) were enrolled and investigated in median 9.0 years after discharge. Only memory tests were performed in 10 patients, mainly due to a lack of formal education necessary for the test results to be reliable. Median full-scale intelligence quotient, memory index, and executive index were 97, 101, and 104, respectively (normal, 100 ± 15). Cognitive function was not reduced in the group with prolonged hypoxemia. Brain imaging showed cerebrovascular lesions in 14 of 38 patients (37%), most commonly in the group treated with venoarterial extracorporeal membrane oxygenation (7/11, 64%). In this group, memory function and executive function were significantly reduced. CONCLUSIONS: Patients treated with extracorporeal membrane oxygenation for respiratory failure may have normal cognitive function years after treatment, if not affected by cerebrovascular lesions. Permissive hypoxemia was not correlated with long-term cognitive dysfunction in the present study. Further prospective studies with minimal loss to follow-up are direly needed to confirm our findings.

Long-Term Survival in Adults Treated With Extracorporeal Membrane Oxygenation for Respiratory Failure and Sepsis.

OBJECTIVE: The use of extracorporeal membrane oxygenation in adults with respiratory failure and sepsis is steadily increasing, but the knowledge on long-term survival in this group is scarce. The aim of the present study was to investigate the 5-year survival rates and causes of late death in this group of patients. DESIGN: Single-center retrospective cohort study. SETTING: Karolinska University Hospital, Stockholm, Sweden. PATIENTS: Adult patients treated with extracorporeal membrane oxygenation for respiratory failure and sepsis between the service being established for adults in 1995 and December 2013. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Survival status was attained from a national Causes of Death registry. Minimal patient background data, along with data on survival and causes of death were collected. Survival rates were calculated using the Kaplan-Meier method. Of 255 subjects, 64% survived to discharge. The median follow-up time in survivors was 4.4 years. There was a high mortality rate within the first months after discharge. In the group of patients who survived the first 90 days after treatment, the 5-year survival rate was 87% and was particularly beneficial in patients treated for infectious diseases (88-100%). Late deaths were seen in most diagnostic groups, but the Kaplan-Meier curves flattened out over time. CONCLUSIONS: Extracorporeal membrane oxygenation treatment in adult patients with respiratory failure and sepsis can be lifesaving in appropriately selected patients. For patients who survive the first months after extracorporeal membrane oxygenation treatment, long-term survival seems good, especially in patients treated for infections.

Long-Term Survival and Causes of Late Death in Children Treated With Extracorporeal Membrane Oxygenation.

OBJECTIVE: Extracorporeal membrane oxygenation has been used in patients with severe circulatory or respiratory failure since the 1970s, but the knowledge on long-term survival in this group is scarce. The aim of the present study was to investigate the 10-year survival rates and causes of late death in children treated with extracorporeal membrane oxygenation. DESIGN: Single-center, retrospective cohort study. SETTING: Tertiary referral center for extracorporeal life support. PATIENTS: Neonatal and pediatric patients treated with extracorporeal membrane oxygenation from 1987 to December 2013. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Survival status was obtained from the national Causes of Death registry. Patient background data along with data on survival and causes of death were collected. Survival rates were calculated using the Kaplan-Meier method. Of 400 subjects, 76% survived to discharge. The median follow-up time in survivors was 7.2 years. There was a high mortality rate within the first months after discharge. In the group of patients who survived the first 90 days after treatment, the 10-year survival rates were 93% in neonates and 89% in pediatric patients and were particularly beneficial in patients whose indication for extracorporeal membrane oxygenation was meconium aspiration syndrome, trauma, or infectious diseases. Late deaths were seen in some diagnostic groups, but the Kaplan-Meier curves plateaued over time. CONCLUSIONS: Children who survive the first months after treatment with extracorporeal membrane oxygenation have a high long-term survival rate. The prognosis is especially favorable in patients with reversible conditions.

Severe Lung Dysfunction and Pulmonary Blood Flow during Extracorporeal Membrane Oxygenation.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) is indicated for patients with severe respiratory and/or circulatory failure. The standard technique to visualize the extent of pulmonary damage during ECMO is computed tomography (CT). PURPOSE: This single-center, retrospective study investigated whether pulmonary blood flow (PBF) measured with echocardiography can assist in assessing the extent of pulmonary damage and whether echocardiography and CT findings are associated with patient outcomes. METHODS: All patients (>15 years) commenced on ECMO between 2011 and 2017 with septic shock of pulmonary origin and a treatment time >28 days were screened. Of 277 eligible patients, 9 were identified where both CT and echocardiography had been consecutively performed. RESULTS: CT failed to indicate any differences in viable lung parenchyma within or between survivors and non-survivors at any time during ECMO treatment. Upon initiation of ECMO, the survivors (n = 5) and non-survivors (n = 4) had similar PBF. During a full course of ECMO support, survivors showed no change in PBF (3.8 ± 2.1 at ECMO start vs. 7.9 ± 4.3 L/min, p = 0.12), whereas non-survivors significantly deteriorated in PBF from 3.5 ± 1.0 to 1.0 ± 1.1 L/min (p = 0.029). Tidal volumes were significantly lower over time among the non-survivors, p = 0.047. CONCLUSIONS: In prolonged ECMO for pulmonary septic shock, CT was not found to be effective for the evaluation of pulmonary viability or recovery. This hypothesis-generating investigation supports echocardiography as a tool to predict pulmonary recovery via the assessment of PBF at the early to later stages of ECMO support.

Conversion from Venovenous to Venoarterial Extracorporeal Membrane Oxygenation in Adults.

No major study has been performed on the conversion from venovenous (VV) to venoarterial (VA) extracorporeal membrane oxygenation (ECMO) in adults. This single-center retrospective cohort study aimed to investigate the incidence, indication, and outcome in patients who converted from VV to VA ECMO. All adult patients (≥18 years) who commenced VV ECMO at our center between 2005 and 2018 were screened. Of 219 VV ECMO patients, 21% (n = 46) were converted to VA ECMO. The indications for conversion were right ventricular failure (RVF) (65%), cardiogenic shock (26%), and other (9%). In the converted patients, there was a significant increase in Sequential Organ Failure Assessment (SOFA) scores between admission 12 (9-13) and conversion 15 (13-17, p < 0.001). Compared to non-converted patients, converted patients also had a higher mortality rate (62% vs. 16%, p < 0.001) and a lower admission Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) score (p < 0.001). Outcomes were especially unfavorable in those converted due to RVF. These results indicate that VA ECMO, as opposed to VV ECMO, should be considered as the first mode of choice in patients with respiratory failure and signs of circulatory impairment, especially in those with impaired RV function. For the remaining patients, Pre-admission RESP score, daily echocardiography, and SOFA score trajectories may help in the early identification of those where conversion from VV to VA ECMO is warranted. Multi-centric studies are warranted to validate these findings.

Milrinone improves diastolic function in coronary artery bypass surgery as assessed by acoustic quantification and peak filling rate: a prospective randomized study.

OBJECTIVE: To compare the effects of a bolus dose of milrinone, 50 microg/kg, to placebo on diastolic function (active relaxation) in patients undergoing on-pump coronary artery bypass grafting (CABG). DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: University hospital. PARTICIPANTS: Twenty-four patients with stable angina and left ventricular ejection fraction >30%, scheduled for elective CABG using cardiopulmonary bypass (CPB), were included. INTERVENTION: Patients were randomized to receive either 50 microg/kg of milrinone (n = 12) or placebo (n = 12) after aortic declamping. MEASUREMENTS AND MAIN RESULTS: The diastolic function of the left ventricle (LV) was measured as peak filling rate (dA/dt [maximal diastolic area change over time]) with transesophageal echocardiography (TEE) using acoustic quantification (AQ) before CPB and 10 minutes after termination of CPB. The normalized peak filling rate (dA/dt)/EDA was also calculated. Active relaxation was statistically significantly increased in the milrinone group compared with the placebo group after CPB. CONCLUSION: Patients undergoing CABG surgery and treated with milrinone after aortic declamping had better diastolic function following cardiopulmonary bypass.

Milrinone increases flow in coronary artery bypass grafts after cardiopulmonary bypass: a prospective, randomized, double-blind, placebo-controlled study.

OBJECTIVE: To compare the effects of a bolus of milrinone, 50 microg/kg, versus placebo on flow in coronary artery bypass grafts after cardiopulmonary bypass (CPB). DESIGN: A prospective, randomized, double-blind study. SETTING: A university hospital. PARTICIPANTS: Forty-four patients with stable angina and left ventricular ejection fraction >30% scheduled for elective coronary artery bypass graft (CABG) surgery were included. INTERVENTION: Patients were randomized to receive 50 microg/kg of milrinone (n = 22) or placebo (n = 22) after aortic declamping. MEASUREMENTS AND MAIN RESULTS: The flow in coronary artery bypass grafts was measured with a transit time flow meter at 10 minutes and 30 minutes after termination of CPB. The hemodynamic evaluation included transesophageal echocardiography, mean arterial pressure (MAP), heart rate, and intracavitary measurement of left ventricular end-diastolic pressure (LVEDP). The flow in the saphenous vein grafts was significantly higher in the milrinone group when compared with the placebo group both at 10 and 30 minutes after termination of CPB (p < 0.001). At 10 minutes, the flow was 64.5 +/- 37.4 mL/min (mean +/- standard deviation) and 43.6 +/- 25.7 mL/min in nonsequential vein grafts for milrinone and placebo, respectively. Corresponding values at 30 minutes were 54.8 +/- 29.9 mL/min and 35.3 +/- 22.4 mL/min. The left internal thoracic artery (LITA) flow was higher in the milrinone group but did not reach statistical significance. The fractional area change was higher, and the MAP and calculated pressure gradient (MAP-LVEDP) were lower at 10 minutes in the milrinone group. CONCLUSION: Milrinone significantly increases the flow in anastomosed saphenous vein grafts after CPB, and has beneficial effects on left ventricular function.

Central hemodynamics during lung recruitment maneuvers at hypovolemia, normovolemia and hypervolemia. A study by echocardiography and continuous pulmonary artery flow measurements in lung-injured pigs.

OBJECTIVE: The impact of lung-recruitment maneuvers on heart function at different volemic levels has not been studied in detail. We therefore investigated the effect on central hemodynamics of lung recruitment maneuvers at hypovolemia, normovolemia and hypervolemia in experimental lung injury. DESIGN: Randomized, controlled, cross-over experimental study. SETTING: Animal laboratory at a university hospital. PARTICIPANTS: Eleven anesthetized and lung-lavaged pigs. INTERVENTION: The animals were randomized to 10-s lung recruitment maneuvers followed by 30-s maneuvers (40 cm H(2)O airway pressure) or vice versa, performed under hypovolemia, normovolemia and hypervolemia. MEASUREMENTS AND MAIN RESULTS: Left-ventricular end-diastolic diameter and cardiac output were measured before, during, and 1 min and 5 min after the lung recruitment maneuver and left-ventricular eccentricity index was calculated for before and during the maneuver. Cardiac output and left-ventricular end-diastolic diameter (within parentheses) decreased significantly during both the 10-s and 30-s lung recruitment maneuvers at hypovolemia, by a mean of 89% (35) and 92% (33), at normovolemia by 75% (33) and 86% (32), and at hypervolemia by 56% (32) and 64% (43), respectively. At hypovolemia, cardiac output was increased above baseline 1-5 min following the 30-s maneuver. Left-ventricular eccentricity index increased significantly during the maneuver, indicating right ventricular dysfunction. CONCLUSIONS: In this animal lung injury model, lung recruitment maneuvers significantly decreased left-ventricular end-diastolic volume and cardiac output at hypovolemia. Hypervolemia did partly counteract this compromise. In addition, a marked right-ventricular dysfunction during the maneuver was found.

The assessment of acute load and contractility changes by left ventricular pressure measurements.

The aim of this study was to establish whether analysis of the left ventricular pressure waveform provides indicative information about cardiac load and contractility and to develop an algorithm for computer-based assessment of changes in these variables. In eight healthy standard breed anaesthetized open-chest pigs, a high frequency response guide-wire mounted pressure sensor was introduced into the left ventricle. Preload reduction was induced by vena cava occlusion, afterload increase by an i.v. injection of phenylephrine and increased contractility by an i.v. injection of adrenalin. Left ventricular pressure waveform analysis was performed by plotting the slope of the pressure curve during the systolic ejection period versus maximal systolic pressure. The analysis revealed characteristic changes in left ventricular pressure and pressure waveform and identified easily discernible reaction patterns in the slope versus maximal pressure plot, specific for each provocation. Analysis of the left ventricular waveform provides indicative information about loading conditions and contractility. The proposed algorithm can easily be implemented in pressure monitoring systems allowing real-time assessment and discrimination of acute changes in preload, afterload and myocardial performance.

Cannula Design and Recirculation During Venovenous Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) is used as a lifesaving rescue treatment in refractory respiratory or cardiac failure. During venovenous (VV) ECMO, the presence of recirculation is known, but quantification and actions to minimize recirculation after measurement are to date not routinely practiced. In the current study, we investigated the effect of draining cannula design on recirculation fraction (Rf) during VV ECMO; conventional mesh cannula was compared with a multistage cannula. The effect of adjusting cannula position was also studied. Recirculation was measured with ultrasound dilution technique at different ECMO flows and after cannula repositioning. All patients who were admitted to our unit between October 2014 and July 2015 catheterized by the atrio-femoral single lumen method were included. A total of 108 measurements were conducted in 14 patients. The multistage cannula showed significantly less recirculation (19.0 ± 12.2%) compared with the conventional design (38.0 ± 13.7). Pooled data in cases improved from adjustment showing reduced Rf by 7%. In conclusion, the choice of cannula matters, as does adjustment of the draining cannula position during atrio-femoral VV ECMO. By utilizing the ultrasound dilution technique to measure Rf before and after repositioning, effective ECMO flow can be improved for a more effective ECMO treatment.

[Good long-term survival after ECMO treatment]. / God långtidsöverlevnad efter ECMO-behandling.

ECMO is used more and more globally, and to date more than 60,000 patients have undergone ECMO treatment. At the ECMO Center Karolinska in Stockholm, Sweden, more than 900 neonatal, pediatric and adult patients with primarily respiratory failure have been treated since 1987. This study investigated 217 consecutive patients of all ages who were treated 1995-2005 at our center, of which 76 % survived treatment. The mean follow-up time was 7.9 years. Of the patients who survived more than 90 days after treatment, 91 % were alive at follow-up 5 years later, similar in all age categories (89-93 %). The highest mortality risk was observed within the first months after ECMO. We conclude that both short and long-term survival is high in all age categories, especially considering the high mortality risk of the patients eligible for ECMO treatment. More studies are needed to evaluate long term prognostic markers, cognitive functions and quality of life, especially in the adult.

Multicenter Experience Using a New Prototype Transnasal Transesophageal Echocardiography Probe.

Transesophageal echocardiography (TEE) is an invaluable diagnostic tool, particularly in patients with inadequate transthoracic echocardiographic examinations. In addition, continuous TEE has been used to monitor ventricular and valvular performance in the intensive care unit and the operating room. However, current generation transesophageal probes have limitations in the critical care setting due to their size. Recently, a prototype miniaturized transesophageal probe was developed to overcome these limitations. This probe was used by five medical centers for 194 examinations. A large proportion of these patients were in the intensive care unit (43%), as well as mechanically ventilated (39%). Seventy percent (70%) of the subjects in this study were intubated nasally with the prototype probe, with a success rate of 88.5%. Oral intubation was successful in every case. Subject tolerance was good, and 25% of the patients were intubated for > 1 h. Nasal intubation with the probe was more likely in intensive care patients, ventilated subjects, and patients who were intubated for > 1 hour. TEE with this miniaturized probe is feasible and safe even in multi-instrumented critical care patients. This probe provides adequate diagnostic imaging capabilities and may allow imaging over prolonged periods of time, making it suitable for the serial monitoring of ventricular performance.