Current status of prolonged extracorporeal membrane oxygenation for acute respiratory failure

Patients treated with venoarterial extracorporeal membrane oxygenation have different baseline risk and outcomes dependent on indication and route of cannulation

OBJECTIVES

To investigate the baseline risk of patients treated with Extracorporeal Cardiopulmonary Membrane Oxygenation (ECMO) in relation to cannulation strategy and indication for ECMO as well as the relation of cannulation strategy with survival and secondary hospitalization outcomes.

METHODS

Severity of illness and predicted mortality risk were assessed in 317 patients. Central cannulation was used in 52 patients unable to wean off cardiopulmonary bypass after cardiac surgery. Peripheral cannulation was used in 179 patients for extracorporeal cardiopulmonary resuscitation (eCPR) and in 86 patients who received ECMO for refractory cardiogenic shock (RCS).

RESULTS

Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were significantly worse (P < 0.01) for peripheral ECMO eCPR (23.2) vs central ECMO (14.6) and vs peripheral ECMO for RCS (18.9). Survival After Venoarterial ECMO (SAVE) scores were significantly worse for peripheral ECMO for eCPR (-7.85) and RCS (-10.38) vs central ECMO (-3.97), and P < 0.01. Peripherally cannulated patients had significantly worse renal function. No significant difference existed for survival to discharge (peripheral ECMO for eCPR, 31%; central ECMO, 44%; peripheral ECMO for refractory cardiac shock, 39.5%; and P = 0.176), although centrally cannulated patients had significantly longer treatment durations compared with peripheral ECMO for eCPR.

CONCLUSIONS

Peripherally cannulated patients with eCPR had significantly worse APACHE II and SAVE scores compared to peripherally cannulated RCS or patients with central ECMO, despite having similar mortality.

Venoarterial extracorporeal membrane oxygenation in heart surgery post-operative pediatric patients: A retrospective study at Christus Muguerza Hospital, Monterrey, Mexico

Objectives

Extracorporeal membrane oxygenation is a life support procedure developed to offer cardiorespiratory support when conventional therapies have failed. The purpose of this study is to describe the findings during the first years using venoarterial extracorporeal membrane oxygenation in pediatric patients after cardiovascular surgery at Christus Muguerza High Specialty Hospital in Monterrey, Mexico.

Methods

This is a retrospective, observational, and descriptive study. The files of congenital heart surgery post-operative pediatric patients, who were treated with venoarterial extracorporeal membrane oxygenation from January 2013 to December 2015, were reviewed.

Results

A total of 11 patients were reviewed, of which 7 (63.8%) were neonates and 4 (36.7%) were in pediatric age. The most common diagnoses were transposition of great vessels, pulmonary stenosis, and tetralogy of Fallot. Survival rate was 54.5% and average life span was 6.3 days; the main complications were sepsis (36.3%), acute renal failure (36.3%), and severe cerebral hemorrhage (9.1%). The main causes of death were multi-organ dysfunction syndrome (27.3%) and cerebral hemorrhage (18.2%).

Conclusion

The mortality rates found are very similar to those found in a meta-analysis report published in 2013 and the main complication and causes of death are also very similar to the majority of extracorporeal membrane oxygenation reports for these kinds of patients. Although the results are encouraging, early sepsis detection, prevention of cerebral hemorrhage, and renal function monitoring must be improved.

Clinical performance of microporous polypropylene hollow-fiber oxygenator

A newly developed polypropylene hollow-fiber oxygenator was used from June 1979, to July, 1980, in 100 patients undergoing open-heart operation. Adequate oxygenation and carbon dioxide elimination were observed throughout perfusion in spite of a relatively low ratio of oxygen flow to blood flow. Plasma hemoglobin level was maintained low after long hours of perfusion. There were no complications related to the oxygenator during or after the operation. Because of its highly efficient performance as well as small size and easy handling, this oxygenator is being used routinely during open-heart procedures in our hospital.

The effect of shear, specific surface, and air interface on the development of blood emboli and hemolysis

Heparinized dog blood was exposed to shear and foreign surfaces in conicylindrical test cells. The cells were injection molded from polycarbonate and were filled using a technique that avoided contact of the blood with air. Particulate-matter formation was measured and was found to be dominated by the surface-to-blood-volume ratio and to be independent of shear rate. Hemolysis was also measured and was found to vary linearly with shear rate and to increase with increasing surface-to-blood volume ratio. Thus, at low shear rates and high specific surface conditions, the degree of hemolysis was found to be minimal while particulate-matter formation was high. The results suggest that the safety of extracoporeal perfusion procedures cannot be inferred from hemolysis measurements alone. In one series of tests, a gas-blood interface was generated at a rate equivalent to the rate of surface renewal in conventional disc oxygenators. The gas-blood interface failed to contribute significantly to the damage indices, which suggests that the apparent superiority of membrane oxygenators may be a result of factors other than the absence of a blood-gas interface.

Oxygenation of the cerebral and coronary circulation with right axillary artery perfusion during venoarterial bypass in primates

The effectiveness of right axillary artery perform in delivering oxygenated blood to the cerebral and coronary circulation during venoarterial bypass in primates was studied. Both right and left common carotid flow measurements and arterial gas measurements revealed high flows and elevated PO2 levels. Incomplete mixing in the ascending aorta was observed from cineangiograms taken at various pump oxygenator flows in 1 animal. The results demonstrated that the brain receives excellent oxygenation at all bypass levels. However, the coronary circulation is perfused primarily by blood ejected from the left ventricle and receives only minimal contribution of well-oxygenated blood from the pump oxygenator circuit. Therefore, the heart may suffer prolonged hypoxemia during long-term venoarterial bypass for acute respiratory insufficiency.

Extracorporeal membrane oxygenation in the treatment of respiratory failure--a review

Extracorporeal membrane oxygenation (ECMO) can be used for the treatment of acute respiratory failure. Based on recent experience in establishing such a method of treatment, this paper reviews those aspects of ECMO that need careful consideration before it can be undertaken. Methods of patient selection for ECMO and the physiological changes associated with it are also discussed.