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.

Advances in therapy for acute lung injury

Despite advances in the therapy for acute lung injury and adult respiratory distress syndrome, mortality remains high. The iatrogenic risk of ventilator-induced lung injury might contribute to this high mortality because the lungs are hyperinflated. Low tidal volume and inspiratory pressure are surrogates for the stress and strain concept; but lung compliance, transpulmonary pressure, and chest wall elastance might differ in individual patients. In previous published studies, an increasing number of patients were treated successfully with extracorporeal support. Extracorporeal membrane oxygenation and interventional lung assist allow ultraprotective ventilation strategies. However, these assists have different technical aspects and different indications.

[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.

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.