THURSDAY, Aug. 12, 2004 (HealthDayNews) -- Suctioning newborns who inhale amniotic fluid containing feces is a measure many doctors take to prevent a potentially fatal respiratory disease, but a new study suggests it makes no difference.
For reasons that can include distress in the womb, a fetus can sometimes pass its first stool -- known in medical circles as meconium -- into the amniotic fluid. Once this happens, the contaminated fluid is swallowed and inhaled into the airways, a condition called meconium aspiration. When the baby is delivered and takes its first breath of air, the meconium can enter the lungs.
The condition is more common than many might think.
About 10 percent of all newborns pass meconium, and around 4 percent of those infants develop meconium aspiration, explained Dr. Nestor Vain, who reports the finding in this week's issue of The Lancet. "The mortality of meconium aspiration is still high, in the neighborhood of 10 percent," he added.
Since the 1970s, suctioning has been practiced widely, despite the lack of any randomized, controlled trials.
The method does pose risks, however, including cardiac arrhythmias, damage of the upper airway, and more.
To try to ascertain whether the benefits outweighed the risks, the researchers randomized about 2,500 babies from 11 Argentine hospitals and one U.S. hospital to receive suctioning or no suction.
About 4 percent of babies in each group developed meconium aspiration syndrome (MAS), and 1 percent to 2 percent required mechanical ventilation. There were no differences in outcomes between the two groups. The researchers looked at death, air leaks, duration of mechanical ventilation, oxygen treatment, and length of hospital stay.
If anything, mortality was lower in the no-suction group (0.7 percent vs. 0.3 percent), pointed out an accompanying editorial.
The editorial also noted some ethical problems with the study, namely the failure to obtain informed consent from the participants.
Vain acknowledged "the lack of informed consent for studies in emergency situations is controversial." He and his colleagues had agreed on the protocol only after prolonged discussions with neonatologists and ethicists from the United States and Europe and after approval from the Neonatal Resuscitation Program of the American Academy of Pediatrics and other bodies.
"An ethically valid informed consent implies not only to get a piece of paper signed under pressure by a patient. It requires a thorough explanation, time to think about it, the chance if the patient needs it to discuss it with relatives or even family physicians, etc.," explained Vain, an associate professor of pediatrics at the University of Buenos Aires School of Medicine in Argentina. "This can not seriously be done in certain circumstances. . . The only real alternative would have been not to perform the study and perpetuate the use of an unproven and potentially damaging therapy."
Fortunately, the incidence of MAS is on the wane.
"MAS has diminished in frequency in the last decade," Vain said. "Since meconium-stained amniotic fluid (MSAF) appears more often with mature fetuses and more so in post-term pregnancies, it is likely that the fact that currently deliveries after term are extremely rare, contributes to the prevention of MAS."
An increase in number of Caesarean section rates may also have helped decrease MAS.
For the time being, Vain said, "Physicians should follow recommendations from scientific institutions."
More information
For more on meconium aspiration syndrome, visit the National Library of Medicine.
