Surgical Innovations

From High Mortality to High Survival

Turning the tables on congenital diaphragmatic hernia

Charles J.H. Stolar, MD, Chief, Division of Pediatric Surgery

Congenital diaphragmatic hernia, or CDH, is one of the most common birth defects, affecting about one in 3000-4000 newborns today. CDH occurs when the diaphragm develops abnormally during gestation, creating a defect, or hole, through which organs such as the intestines migrate into the chest. The result is compression and impairment in the development of the lungs, including pulmonary hypertension, a dangerous condition involving high blood pressure in the lungs. Among babies with CDH, pulmonary hypertension can lead to heart failure and is the most significant cause of illness and death. Fortunately, medicine has made tremendous progress against pulmonary hypertension during the past 25 years.

But as recently as 30 years ago, the prognosis for babies born with CDH offered little hope. So when Charles J. Stolar, MD, Chief, Division of Pediatric Surgery, brought the innovation known as ECMO to Morgan Stanley Childrens Hospital of NewYork-Presbyterian (formerly Babies Hospital) in 1982, its benefits were quickly noted. ECMO, or extracorporeal membrane oxygenation, served as a biomedical placenta for critically ill infants, providing an artificial heart, lung, gastrointestinal tract, and kidney. "With this safety net, survival rates began to climb," Dr. Stolar recounts. At that time,Morgan Stanley Childrens was the third institution in the world to use ECMO for newborns.

Turning the tables on congenital diaphragmatic hernia

Alix O'Connor, above, underwent surgery to repair her congenital diaphragmatic hernia when she was two days old. According to her father, Brian O'Connor, "Dr. Arkovitz was everything we could have hoped for in a pediatric surgeon – he was informative, friendly, kind, caring, and always gave us as much time as we needed to ask questions. We were grateful to have been at Columbia with truly wonderful surgeons, doctors, and nurses. We genuinely look forward to Alix's check-ups with Dr. Arkovitz (now on an annual basis) to catch up with our friend who continues to take excellent care of our daughter."

Building on the success achieved through the use of ECMO, Dr. Stolar sought additional ways of improving the care of babies with CDH. The late L. Stanley James, MD, Chief of Neonatology, John Driscoll, MD, then Chairman of Pediatrics, and Jen-TienWung, MD, Director, Neonatal Respiratory Care, were just beginning to apply new respiratory care principles to patients with CDH. These strategies proved effective at minimizing damage to the vulnerable lungs of premature infants with too much pressure and oxygen toxicity. Having observed the significant benefits of this approach, the team began applying these gentler strategies to the more challenging group of term infants with CDH. Their innovative work further improved outcomes within five years, raising survival rates of children with CDH to 85% at Morgan Stanley Childrens Hospital.

"We took a very difficult problem, put together an outstanding team of physicians, residents, and nurses…and figured out how to solve it," says Dr. Stolar. "A very high death rate turned into a very high survival rate."

With this newfound success, a new generation of patients began surviving into childhood and adulthood for the very first time. Although they universally undergo corrective surgery to repair their hernias shortly after birth, such patients often require specialized medical care for unique, sometimes complex conditions associated with their CDH or subsequent treatments.

To meet the special care needs of this population, Marc S. Arkovitz, MD, Assistant Professor of Surgery, Columbia University College of Physicians and Surgeons, organized a multidisciplinary CDH clinic in 2005. In this unique clinic, specialists including neonatologists, pediatric cardiologists, pulmonologists, geneticists, surgeons, and developmental pediatricians work together to care for each patient. The Columbia clinic now treats more patients with CDH than most other U.S. institutions today.

Gentle Ventilation for CDH Babies

Because babies with congenital diaphragmatic hernia (CDH) have underdeveloped, or hypoplastic, lungs, they often are unable to breathe at birth. Moreover, the lack of adequate blood vessels in hypoplastic lung tissue results in inadequate blood flow, causing high blood pressure in the lungs—a dangerous condition called pulmonary hypertension. Because of these critical problems, many newborns with CDH require help breathing from a ventilator.

Ventilators have traditionally been able to sustain about half of babies long enough to undergo and recover from surgery to repair their hernias, and eventually to develop adequate lung tissue and breathe independently. Those administering the ventilation have strived to achieve normal blood levels of oxygen and carbon dioxide by forcing the correct pressure into these tiny babies' lungs. But the application of too much pressure can damage undeveloped lungs, leading to sometimes serious, even fatal, chronic lung disease.

Now, a technique called "kinder and gentler ventilation" has proven superior to the traditional approach. Developed by Jen-TienWung, MD, Director, Neonatal Respiratory Care, gentle ventilation seeks to apply the minimum level of respiratory support needed, rather than to achieve normal blood levels of oxygen. Dr. Wung began using lower ventilation pressures in babies with CDH after he observed that lower pressures significantly improved survival among babies who aspirated meconium.

Today, the survival rate for babies who receive ventilator support at the Morgan Stanley Childrens Hospital Neonatal Intensive Care Unit is almost 90%, compared to the national average of 50-60%.

Among the innovative techniques promoted at the CDH clinic is the use of minimally invasive surgery rather than open surgery to repair babies' hernias. Since 2005, Dr. Arkovitz has been performing diaphragmatic hernia operations through a thoracoscopic approach whenever possible, using small incisions in the chest. "Thoracoscopic surgery is less stressful for the baby than open surgery," says Dr. Arkovitz. About one third of babies may be stable enough to qualify for this method, while others still require an open surgical approach.

Paired with the clinical program is a research program aimed at understanding the causes of CDH. With new, higher resolution genomic technology now available, Wendy Chung, MD, PhD, Director of Clinical Genetics, Columbia University College of Physicians and Surgeons, is investigating the genetic mutations involved in this condition. Using the highly advanced methods that help predict prognoses in cancer patients, Dr. Chung is working to detect abnormalities in chromosomes, or even parts of chromosomes, that may be responsible for CDH.

"By determining the genetic abnormalities associated with CDH, we hope to be able to give better answers to the questions patients ask, such as which children will have problems in addition to the CDH, and will this ever happen again in our family?" Dr. Chung says. The ability to detect wayward bits of chromosomes is still in the research phase, and may become clinically available in two to three years, according to Dr. Chung. "By developing the data to make this technology useful, the potential is there to use it for prenatal testing as well as after birth."

A key area of the CDH team's focus involves the study of pulmonary hypertension, dangerously elevated blood pressure in the lungs. The severity of this condition is correlated with how well a child fares, according to Dr. Arkovitz. Babies with mild pulmonary hypertension have the best prognosis, while those with severe pulmonary hypertension tend to face the gravest risk for developing heart failure. No one knows why this is, however—whether there is something inherently different about the development of babies with severe pulmonary hypertension, if there is a genetic cause, or if there is something about the lungs being compressed that causes this difference in long-term outcomes.

For more information, visit www.columbiasurgery.org, or call 800.227.2762.