Hyperbilirubinemia: Recognition, Care and Management of Term and Near-Term Infants

Objectives

What is the Problem?

Definition of Terms

Production, Metabolism, Transport and Excretion

Assessment

Practice Standard

Current Treatment

Education

Bibliography

Quiz

Main Lab Page

What are the current treatment modalities used for the management of neonatal hyperbilirubinemia?

The treatment modalities used to manage infants who are at risk for or who have hyperbilirubinemia include:

Preventive strategies:

• Use of pharmacologic agents
• Exchange transfusions
• Phototherapy

Preventative strategies include:

1. Early initiation of feeding and increased frequency of breast-feeding to reduce enterohepatic shunting, stimulate intestinal motility, and establish normal bacterial flora.

2. Providing a neutral thermal environment will reduce the risk of hypothermia and the release of fatty acids that can interfere with albumin binding and thus increase levels of indirect (unbound) bilirubin.

3. Avoiding any trauma during labor and delivery reduces bruising and hematoma formation that increase hemoglobin destruction and thus bilirubin production.

4. Preventing hypoglycemia and hypoxia will enhance liver enzyme function and promote conjugation.

5. Administering Rho (D) immune globulin to Rho (D)-negative women with Rho (D)-positive infants.

Pharmacologic agents, such as Phenobarbital, have been tried pre and postnatally with varying success. Phenobarbital increases microsomal enzymes to augment the conjugation of bilirubin. Prenatal use (administered to the mother in the last trimester) has been successful in infants with documented Rh incompatibility, but these agents are not generally used postnatally except in high-risk situations, such as severe erythroblastosis fetalis.

Inert substances such as agar and charcoal (only when administered in the 1st 12 hours of life) have been used in an attempt to absorb bilirubin in the intestines and reduce the enterohepatic shunting. These substances are not commonly used because of equivocal results.

Exchange transfusions are used primarily for infants with hemolytic disease to remove antibody-coated red blood cells and bilirubin, as well as some of the circulating maternal antibodies. It is also used to correct the anemia associated with excessive hemolysis or if the serum bilirubin rises rapidly toward a range of high concern for neurotoxicity and phototherapy has not been effective. Exchange transfusions may need to be repeated more than once before stabilization is attained. They are not risk free with the estimated morbidity at about five percent and mortality at 0.5 percent. The development of phototherapy replaced exchanged transfusions as the predominant treatment for unconjugated hyperbilirubinemia.

Phototherapy is the most common therapy for hyperbilirubinemia. It is the primary treatment of choice except in cases of rapidly increasing unconjugated bilirubin levels. Phototherapy is used to avert bilirubin toxicity though it does not treat the cause of the hyperbilirubinemia. However, in most cases, phototherapy reduces the rise of serum bilirubin concentrations regardless of maturity, the presence or absence of hemolysis or skin pigmentation.

The mechanism by which phototherapy reduces unconjugated bilirubin and the exact mode of excretion are not fully understood. It is theorized that photoisomerization and photo-oxidation change bilirubin into a water soluble, excretable form. Also, phototherapy is thought to enhance hepatic secretion of unconjugated bilirubin and to increase bowel transit time.

It is thought that light reduces bilirubin by two mechanisms:

1. Photoisomerization converts indirect bilirubin to water-soluble photoisomers by rearranging the bilirubin molecule's chemical groups to produce photobilirubin or rearranging its atoms to produce lumirubin. These photoisomers (photobilirubin and lumiribin) can then be excreted into bile without conjugation. Lumirubin is thought to be the major pathway by which bilirubin is eliminated.

2. Photosensitized oxidation is a minor pathway for bilirubin removal. The bilirubin molecule absorbs light energy, which is transferred to oxygen, forming a reactive oxygen molecule. The bilirubin is then oxidized, producing water-soluble breakdown products that can be excreted in urine.

There are three major methods of providing phototherapy:

1. Bank bilirubin lights
2. Spotlights
3. Fiber optic blankets or vests

Bank lights covered with Plexiglas for safety should be used no more than 36 cm from the infant to deliver adequate doses.

Halogen lights should be placed according to the manufacturer's recommendations to prevent the potential for thermal burns.

Fiberoptic devices may be placed under the infant, if used in combination with other phototherapy, or wrapped around the infant if used alone.

Fluorescent bulbs, such as cool white, daylight, special blue, used in phototherapy should be check for irradiance daily with a photometer, and the bulbs should be replaced if they have lost more than 20% of acceptable output.