OBSTRUCTION OF AIRWAY
ANY OBSTRUCTION of the upper airway (nose, throat, larynx. trachea) can cause noisy breathing (stridor), which is a not uncommon symptom in infants. Resistance to the passage of air sets up vibrations, which cause noise, and severe obstruction can cause real difficulty in breathing. Severe stridor can he recognized shortly after birth, but the milder forms may go undetected until after the baby has been taken home from the hospital. Whereas croup is the main cause of stridor in older children, the most common cause for infants is some congenital abnormality, or birth defect. of the airway. Laryngomalacia (literally, softening of the larynx) is perhaps the most common of these defects.
The cartilages comprising the voice box should be firm and relatively inflexible but in this condition are overly pliable. In breathing they collapse and in-crease the resistance. Babies with laryngomalacia tend to improve as they grow older. By the age of one, the stridor in most cases will disappear. Children with congenitally underdeveloped jawbones may have an associated displacement of the tongue resulting in partial obstruction of the airway and, of course. stridor.
The breathing difficulty will be relieved when the jawbones have grown enough for the tongue to assume a more normal position. In choanal atresia a bony overgrowth blocks the rearmost part of one or both nasal passages. If both sides are affected, the child cannot breathe through his nose at all and at feeding time will be in a great
In biliary atresia, an uncommon congenital condition, the major bile ducts are either too malformed to carry bile from the liver to the intestine, or are missing altogether.Bile, which is a thin yellow fluid, is a vehicle for the excretion of a number of body products, including bilirubin . the major component in the breakdown of aged red blood cells.
Bile also contains chemical compounds that are important in the digestion of fats. Bile is produced in the liver cells. Microscopic channels carry the bile from these cells to larger tubes in the liver that, like streams joining in a river, come together to form the common bile duct, and this duct connects the liver with the duodenum, the uppermost section of the intestine. There is one major branch, the cystic duct, leading to the gallbladder, which is the storage place for bile. Obstruction to bile flow, from whatever cause, can bring on progressive damage and scarring of the liver with consequent impairment of function. When the outflow of bile is blocked, all the substances normally excreted in the bile back up into the bloodstream. Bilirubin being one of these substances. jaundice is thereby an important symptom of biliary obstruction (although this condition will be rare among all the causes of jaundice in the newborn (see pages 382-86D . The in-sufficiency of bile in the intestine results in incomplete digestion of fatty foods. Chronic diarrhea and the signs of poor nutrition will be the symptoms. If unrelieved.
complete obstruction of bile flow causes so much liver damage that death results. In infancy the common and cystic ducts and the gallbladder, any one or all three, may be involved in a biliary obstruction. There are two major classes of malformation: those in which some part of the common duct exists and those in which it is missing. If any pan of the duct is present and in normal communication with the smaller branches and tubes within the liver, it is in theory possible to obtain normal flow of bile through surgery. If the duct is missing, a new linkage is impossible and liver failure, usually at between one and three years of age. is inevitable.
Unfortunately, this prognosis holds for most of the infants born with defective biliary systems. (Remember, though, that this is statistically a rare condition among the entire class of newborns.) Experiments with transplantation of the liver offer hope for the future. Although the symptoms are similar, congenital biliary atresia must be distinguished from hepatitis (inflammation of the liver). The two conditions arc difficult to tell apart, but it is important to diagnose biliary atresia as early as possible.
The sooner a repairable biliary atresia can be corrected, the less liver damage will result. The diagnosis can be made only by taking a small specimen of the liver (biopsy) for examination under the microscope. While the infant is in surgery for this procedure an X ray is taken to determine where the obstruction is and whether it can be corrected. There is an unfortunate catch here, however. If the infant’s trouble is hepatitis, there is risk that anesthetizing him will make it worse. As a compromise, it is common practice to wait from four to eight months in the hope that hepatitis, if that is the difficulty, will clear up.