Lung recovery high after ECMO in near-fatal pediatric asthma

TORONTO – Extracorporeal membrane oxygenation (ECMO) is associated with lung recovery rates as high as 90% in pediatric patients with near-fatal asthma, but the risk of complications was also high and the cannulation technique employed made a significant difference to outcomes, according to a study presented at the CHEST annual meeting.

“ECMO for near-fatal asthma is a potentially life-saving intervention, however, clinicians should be aware of the potentially severe complications, particularly with veno-arterial cannulation in this population,” said Rebecca Kohlberg-Davis, MD, a pediatric resident at Connecticut Children’s Medical Center, Hartford.

^{Debra L. Beck/Frontline Medical News}

Dr. Rebecca Kohlberg-Davis

ECMO is being used increasingly in the setting of near-fatal pediatric asthma but there are limited data on outcomes in this population. Dr. Kohlberg-Davis and her colleagues conducted a retrospective analysis of all children with asthma who were treated with ECMO using the Extracorporeal Life Support Organization (ELSO) registry.

Between 1988 and 2016, 371 children with status asthmaticus underwent ECMO cannulation using one of two methods. Sixty-five percent were treated with ECMO using veno-venous (VV) cannulation and 33% were treated using veno-arterial (VA) cannulation. Both VV and VA require insertion of a cannula to take deoxygenated blood from a central vein or the right atrium. VA ECMO returns the oxygenated blood, under pressure, to the arterial side of the circulation (typically to the aorta), supporting cardiac output, while VV ECMO returns oxygenated blood back to a large vein and does not support circulation.

The median age of the study participants was 7.5 years and 56% were male. The median ECMO run duration was 123 hours.

Overall, lung recovery was seen in 83% of patients, and 77% were discharged from the hospital. Of the children who received VV cannulation, 90% experienced lung recovery, while VA cannulation was associated with only a 69% rate of lung recovery and significantly more complications. Among those who experienced lung recovery, those who received VV cannulation had a 3.6-fold higher likelihood of survival (P = .006), Dr. Kohlberg-Davis reported.

At presentation, 88% of patients had hypercarbic respiratory failure, 34% had hypoxemic respiratory failure, and 27% had mixed respiratory failure. Children with hypercarbic respiratory failure were more likely to receive VV cannulation (P = .003), while children with hypoxemic or combined respiratory failure were more likely to receive VA cannulation. Those with hypoxemic respiratory failure had a significantly lower likelihood of lung recovery (odds ratio, 4.9; P less than .0001), she said.

Eighty percent of runs were associated with one or more complications and 20% had three or more complications. Of that 80%, most involved cardiovascular complications (53%), while 36% were hemorrhagic and 35% were mechanical. The most common cardiovascular complications included the need for inotropic support (in 39% of patients) and hypertension requiring vasodilators (in 18% of patients). The most common hemorrhagic complications were cannula-site bleeding (23%) and surgical-site bleeding (8%), while mechanical complications were mostly clots (19%) and cannulation problems (12%).

Children who received VA cannulation had a significantly higher rate of neurologic complications, compared with those who received VV cannulation (22% vs. 5%), and these included cerebral hemorrhage or infarct in 6% and clinical brain death in 5%.

“If early cannulation with VV ECMO could prevent the need for VA ECMO, this might lead to lower neurological complication and increased survival,” said Dr. Kohlberg-Davis. Current guidelines recommend considering cannulation at an oxygenation index – used to measure the fraction of inspired oxygen and its usage within the body – between 40 and 60. This study suggests that initiating cannulation at a lower OI is associated with better outcomes and fewer complications, she said.

The authors reported having nothing to disclose.