Public Release: 

Inhaled Treatment Effective For Hypoxic Respiratory Failure

NIH/Eunice Kennedy Shriver National Institute of Child Health and Human Development

Treatment with inhaled nitric oxide is an effective therapy for hypoxic respiratory failure in term and near-term infants, according to the lead article in the February 27, 1997 New England Journal of Medicine. The new treatment offers a significant alternative to the standard surgical treatment, which may cause a loss of one of the carotid arteries and carries a significant risk of neurological damage, explained one of the principal investigators of the study, Dr. Linda Wright of the Pregnancy and Perinatology Branch of the National Institute of Child Health and Human Development (NICHD).

The study was performed as a collaboration between the investigators in the Neonatal Research Network of the NICHD and the Canadian Inhaled Nitric Oxide Study (CINOS) group. The study was stopped on May 2, 1996, 2 months before its scheduled completion date, after review of the results by the study's Data and Safety Monitoring Committee revealed that inhaled nitric oxide significantly reduced the need for surgical intervention.

Hypoxic respiratory failure is a potentially fatal condition in which newborn infants, for a variety of reasons, cannot breathe in enough oxygen to survive. Among the causes of hypoxic respiratory failure are respiratory distress syndrome, in which the lungs are immature and poorly formed; meconium aspiration, in which an infant, shortly before birth, inhales amniotic fluid which has been contaminated by a bowel movement; pulmonary hypertension, or high blood pressure in the lungs; and congenital diaphragmatic hernia, a malformation of the diaphragm associated with inadequate lung formation.

Until now, the only effective treatment for hypoxic respiratory failure has been a surgical treatment called ECMO (extracorporeal membrane oxygenation), a highly invasive procedure in which blood is removed from a large vein that empties into the infant's heart, pumped into a system that oxygenates the blood, and then returned to the large vessels in the infant's neck. As a result of this procedure, one of the carotid arteries, which carries blood to the right side of the brain, is often permanently lost. ECMO is expensive, requires constant monitoring, and is associated with a nearly 20 percent rate of neurologic abnormalities. Of the 1,000 newborns in the U.S. who are treated with ECMO each year, approximately 82 percent survive. "Because of the risks and costs associated with ECMO, a non-invasive alternative treatment such as nitric oxide therapy represents a major advance," Dr. Wright said.

In all, 235 term infants who were less than 14 days old and who had received the maximum conventional therapy were enrolled in the study with the informed consent of their parents. The infants were randomized to one of two groups, 121 to the control group, which received the maximum conventional therapy of 100 percent oxygen, and 113 to the intervention group, which received a mixture of oxygen and nitric oxide.

At the study's conclusion, 64 percent of those who received conventional therapy either were referred to treatment with ECMO or had died. In contrast, 46 percent of the nitric oxide group were referred for ECMO treatment or had died. In all, death occurred in 14 percent of the nitric oxide group and 17 percent of the control infants (no significant difference).

Dr. Wright added that the nitric oxide therapy could not only benefit the approximately 1,000 infants who undergo ECMO each year, but could also benefit an estimated 2 to 3 times as many children.

Nitric oxide relaxes the blood vessels that line the lung, allowing it to absorb more oxygen. Unlike other treatments that expand the blood vessels in the lung, nitric oxide does not decrease blood pressure elsewhere in the body.

Because hypoxic respiratory failure is an uncommon disease in newborns, previous studies that have attempted to prove that nitric oxide reduces the incidence of death or the need for ECMO have failed because they have been unable to enroll enough infants to assess the impact of nitric oxide on these important outcomes. Because this study was conducted within the NICHD's Neonatal Research Network in collaboration with the CINOS group (funded by the Medical Research Council of Canada), investigators were able to enroll enough infants in fewer than 18 months to be able to evaluate the therapy. Eight Neonatal Research Centers and 11 CINOS centers participated in the trial.

Established in 1986, the Neonatal Research Network is a national network of 14 tertiary neonatal centers which conduct multi-center trials in neonatology, focusing specifically on the optimal management and care of infants in neonatal intensive care units.

        Participating Neonatal Research Network Centers
        Co-chairs of the Neonatal Inhaled Nitric Oxide Study
        Dr. Richard Ehrenkranz, Yale University
        Dr. Neil Finer, University of Alberta
        (now at University of California at San Diego)

        Case Western Reserve University                 Dr. Avroy Fanaroff 
        Cleveland, OH                                   Dr. Eileen Stork

        Wayne State University                          Dr. Seetha Shankaran
        Detroit, MI                                     Dr. Ganesh Konduri

        University of Tennessee at Memphis              Dr. Sheldon Korones
        Memphis, TN                                     Dr. Dennis Crouse

        University of Cincinnati                        Dr. Edward Donovan
        Cincinnati, OH                                  Dr. Richard Brilli

        Indiana University                              Dr. James Lemons
        Indianapolis, IN                                Dr. Greg Sokol

        Stanford University                             Dr. David Stevenson
        Palo Alto, CA                                   Dr. Krisa Van Meurs
                                                        Dr. William Rhine

        University of New Mexico                        Dr. Lu-Ann Papile
        Albuquerque, NM                                 Dr. Mark Crowley

        Women and Infants Hospital,                     Dr. William Oh
        Providence, RI                                  Dr. Monica Kleinman

Participating Centers with the Canadian Inhaled Nitric Oxide Study Group

        Royal Alexandra Hospital                        Dr. Abe Peliowski
        Edmonton, Alberta                               Barbara Kamstia                 

        Foothills Hospital                              Dr. Nalini Singhal
        Calgary, Alberta

        University of Alberta Hospital                  Dr. Keith Barrington
        Edmonton, Alberta

        British Columbia Children's Hospital            Dr. Alfonso Solimano
        Vancouver, BC

        Texas Children's Hospital                       Dr. Mary Wearden
        Houston, TX

        Montreal Children's Hospital                    Dr. Ann Johnston
        Montreal, Quebec

        Children's Hospital of
        Eastern Ontario                                 Dr. Robin Walker
        Ottawa, Ontario

        McMaster University                             Dr. Haresh Kirpalini
        Hamilton, Ontario

        Health Sciences Center                          Dr. Carlos Fajardo
        Winnipeg, Manitoba

        Royal University Hospital                       Dr. Koravangattu Sankarhan
        Saskatoon, Saskatchewan

        Sherbrooke University Hospital                  Dr. Pierre Blanchard
        Sherbrooke, Quebec

        Data Coordinating Center:
        The George Washington University                Dr. Joel Verter
        Biostatistical Coordinating Center              Dr. Naji Younes
        Rockville, Md


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