January 19, 2010

H1N1 lessons: Critical illness in kids unpredictable, survivable

Lessons learned from the first 13 children at the Johns Hopkins Children’s Center to become critically ill from the H1N1 virus show that serious complications developed quickly, unpredictably, with great variations from patient to patient and with serious need for vigilant monitoring and quick treatment adjustments.

These and other findings were published online Dec. 31 in the journal Pediatric Critical Care Medicine in what is believed to be the first published analysis of critical H1N1 illness in children.

The Johns Hopkins analysis shows that 12 out of the 13 very ill children, all of whom were admitted to the pediatric intensive care unit and survived, had underlying medical conditions that made them more vulnerable, including sickle cell disease, asthma and HIV. Complications varied from temporary kidney failure to acute respiratory distress syndrome and dangerously low oxygen levels and blood pressure.

An important finding was that rapid screening tests were initially negative in eight of the 13 children, underscoring the need for more-sensitive tests.

Therefore, the researchers say, all critically ill children with flulike symptoms should be treated preemptively with antiviral medications, regardless of test results. Past research has shown that antiviral medications are most effective in healthy people with the flu if taken within 12 to 48 hours after symptoms begin. Johns Hopkins currently treats all hospitalized patients with unexplained fever and flulike symptoms regardless of test results.

“Our most surprising, and perhaps most important, finding is that the H1N1 virus behaves unpredictably and variably from one patient to the other, and even within the same patient from day to day, so we must be on our toes and react fast by adjusting therapy,” said lead investigator Justin Lockman, a pediatric critical care specialist at Johns Hopkins Children’s.

Investigators caution that more and larger studies are needed to guide future practice and recommendations for H1N1 treatment in children.

Senior investigator David Nichols, professor of anesthesiology/critical care medicine and pediatrics at the Johns Hopkins School of Medicine, said, “Our analysis did reveal some interesting patterns and trends, but it also showed us how much more we have to learn about the behavior of this new and intriguing virus.”

In total, the Johns Hopkins team analyzed data from 140 pediatric patients diagnosed with H1N1 between June 2009 and August 2009. The novel flu strain, originally called swine flu, emerged for the first time in April 2009.

Other findings reported in the article include:

Asthma was the most common underlying chronic condition (11 of the 13 critically care children had it), followed by neuromuscular diseases like cerebral palsy.

Nearly half the children became so sick they needed a ventilator to help them breathe. However, no children died or required ECMO (extra-corporeal membrane oxygenation), a last-resort critical-care device that takes over the patient’s lungs and heart to oxygenate and circulate the blood when the patient’s organs can no longer do so.

More often than previously believed, one-fourth of the children developed dangerous secondary bacterial infections, which points to the need for watchful monitoring for such infections in children with H1N1.

Co-investigators were William Fischer, Trish Perl and Alexandra Valsamakis, all of Johns Hopkins.