DOI: 10.1097/PCC.0b013e3181ab8913
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Issn Print: 1529-7535
Publication Date: 2009/07/01
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Excerpt
Dr. Tembo and colleagues commented that the management of septic shock in children has changed considerably over the 18-year period analyzed in our study (1) and questioned our use of corticosteroids and vasopressin. It is worth emphasizing that although these drugs are often used in pediatric septic shock, they are not universally regarded as standard care and there is little evidence that they improve survival (2). Furthermore, the children with septic shock who might benefit from ECMO are those with a predominantly cardiogenic pattern of shock and vasopressin, as a pure vasoconstrictor, may not be of lasting benefit. Although we cannot provide data on corticosteroids, we documented vasopressin use in six patients, in which three of whom survived.
The use of ECMO for sepsis and septic shock has changed during the past 30 years. In the 1970s and early 1980s, sepsis was regarded as a contraindication to ECMO. By the mid 1990s, this was shown to be unfounded in both neonates (3, 4) and older children (5). In 1997, Goldman et al (6) showed that ECMO could be safely applied to children with meningococcemia who had either respiratory or circulatory collapse, using venovenous or venoarterial ECMO, respectively. Along with these changes in indications for ECMO, there were improvements in circuit technology, such as the development of polymethylpentene-coated hollow-fiber oxygenators and smaller, more efficient centrifugal pumps.
We believe that our study has formulated another possible step forward in the evolution of ECMO for children with septic shock, specifically the concept of “adequate flow.” If flow through the ECMO circuit is insufficient to reverse cellular hypoxia or is being unevenly distributed to the patient, ECMO is not being optimally used. Both these problems are overcome with central cannulation. Although we agree with Dr. Tembo and colleagues that adding a second venous cannula may help improve circuit flows (as we did in six of our patients [1]), the position of the arterial cannula is still extremely important. Cannulating the ascending aorta allows a larger cannula to be inserted, augmenting the maximum flow that can be safely achieved as well as avoiding the problem of maldistribution of oxygenated blood away from the patient’s coronary and cerebral circulations in patients with concomitant respiratory failure (7). We observed a significant improvement in the survival of patients who were cannulated centrally over those cannulated peripherally (73% vs. 38%, p = 0.05) (1) and, despite the obvious limitations of our study, suggest that this strategy could be considered by other ECMO centers.
The authors have not disclosed any potential conflicts of interest.
