U

Underdeveloped Lungs

What is Lung Hypoplasia?
What Causes Lung Hypoplasia?
Who Gets It?
How does it cause disease?
Common Findings
Diagnosis
Treatment
Prevention

Reese H. Clark, M.D.
Director of Research
Pediatrix Medical Group, Inc.
Fort Lauderdale, Florida

What is Lung Hypoplasia?
In general terms lung hypoplasia means under developed lungs. Hypo means small, plasia means formed. The lungs are a vital organ and without them we can not live. The lung is made up of small gas exchange units called alveoli. Alveoli are thin walled structures that are surrounded by small veins and arteries called capillaries. Gas in the alveoli is exchanged with gas in the blood allowing oxygen to be delivered to tissue as a key element for body function and carbon dioxide to be eliminated from the body.
When the lung is hypoplastic the number of alveoli that are available for gas exchange are decreased. If the lungs are very hypoplastic the number of gas exchange units reaches a critically low level and adequate gas exchange can not be maintained. Newborn babies with very hypoplastic lungs die of lung failure in the first few days of life if they cannot be supported long enough to grow more lung.

What Causes Lung Hypoplasia?
The lung begins forming very early in fetal development. Any thing that restricts growth of the chest can cause the lung to be under developed. It is important to distinguish lung hypoplasia from lung immaturity. They are not the same things though, functionally, they have the same effect. Both lead to inadequate gas exchange and lung failure. Babies born prematurely have immature lungs with a developmental normal number of alveoli. The goal in caring for these babies is to support them in a manner that prevents injury to the lung. If injury is avoided these babies can have normal lung development.
In contrast events that impact fetal lung growth may effect future lung growth and may prevent babies with lung hypoplasia from ever developing a normal complement of alveoli.
The most common causes of poor fetal lung growth are: inadequate amniotic fluid, congenital diaphragmatic hernia, hydrops fetalis, certain types of dwarfism, pulmonary agenesis, cystic adenomatous formation, and cystic hydroma. In each of these anomalies, the fetal lung does not grow to its normal size. Inadequate amniotic fluid is most commonly due to early leaking of amniotic fluid due to premature rupture of the membranes that surround the fetus. This is known as oligohydramnios (too little amniotic fluid). If amniotic fluid leaks out from around the baby, the chest wall movement that occurs with fetal breathing may be restricted. Fetal breathing and adequate fluid pressure are both believed vitally important for normal lung development.
The second most common cause for inadequate amniotic fluid is fetal renal anomalies. Amniotic fluid is produced by the amniotic membranes and by the fetal kidneys. Severe abnormalities of the kidneys (eg. polycystic kidneys, hydronephrosis, renal agenesis) can cause too little amniotic fluid to be formed (oligohydramnios) and are commonly associated with lung hypoplasia. Babies with kidney and lung problems have a particularly grave prognosis because they have two organ systems that have failed.
Structural problems in development may also impair lung growth. In babies with congenital diaphragmatic hernia, the diaphragm that separates the lung form the abdomen fails to develop. As a consequence, the intestines move into the chest cavity and restrict lung growth. Similarly, certain types of dwarfism or congenital anomalies of the lung restrict the area in which the lungs can grow normally. While most of these anomalies are rare (1:3000), they are commonly life threatening.

Who Gets It?
. Babies born to mothers with prolong rupture of amniotic membranes and oligohydramnios.
. Newborns with severe renal anomalies, born to mother with resultant oligohydramnios.
. Newborns with certain congenital anomalies
Congenital diaphragmatic hernia
Thanahoric dwarfism
Cystic hydroma
Cystic adenomatosis malformation
Newborns with hydrops fetalis
Newborns with neuromuscular diseases

How does it cause disease?
Small lungs fail to accomplish normal gas exchange (oxygen in, carbon dioxide out.)

Common Findings
The presentation is variable and dependent on the severity of the hypoplasia. Some babies may present with mild tachypnea (fast breathing) others may have signs of severe respiratory failure: fast breathing, labored breathing, blue color, and gasping.

Diagnosis
The most important factors leading to a diagnosis are: history of fetal anomalies associated with lung hypoplasia, history of mom having too little amniotic fluid, and a chest radiograph showing small lungs.

Treatment
Currently, treatment is primarily supportive. This means that there is currently no available medicine that makes babies grow lungs. So, until lung growth occurs to an extent that the lung can support normal gas exchange, the babies must be supported by artificial means. The main problem is that all modes of artificial respiratory support are associated with lung injury. The trick is to support normal gas exchange without causing injury and to support good nutrition so that the lung can grow. Babies have an incredible capacity to grow and develop. In time, if the lung is not too underdeveloped the baby can usually wean off artificial support and go home. Therapies used to support gas exchange in order of level of support are: oxygen, assisted ventilation, high frequency ventilation, and extracorporeal membrane oxygenation (ECMO).

Prevention
There are no methods for preventing babies with certain anomalies from developing lung hypoplasia. Research is currently focused on maintaining normal amniotic fluid and pressure and prevention of restriction of lung growth. Investigators are also looking at factors that promote normal lung growth. The hope is that neonates with lung hypoplasia might be treated with lung growth factors that would promote growth of normal lung, reduce the need for artificial support and its attendant propensity to cause injury and allow for a healthier life.

About the Author
Dr. Clark, a leading clinical researcher for the care of critically ill newborns, is the Director of Research for Pediatrix Medical Group, Inc. and a Consulting Associate Professor at Duke University.
A native of North Carolina, Dr. Clark earned both his Bachelor of Arts and medical degrees from the University of North Carolina at Chapel Hill. He completed his pediatrics residency and his neonatal fellowship at Wilford Hall United States Air Forces Medical Center. He is a board-certified pediatrician and neonatologist.
Copyright 2012 Reese H. Clark, M.D., All Rights Reserved

Urinary Tract Infection

What is a urinary tract infection?
What causes a urinary tract infection?
How does it cause disease?
Who gets a urinary tract infections?
What are the common findings?
How is a urinary tract infection diagnosed?
How is a urinary tract infection treated?
What are the complications?
How can a urinary tract infection be prevented?
What research is being done?
Links to other information

James K. Todd, M.D.
Professor of Pediatrics, Microbiology, and Preventive Medicine
University of Colorado School of Medicine
Denver, Colorado
What is a urinary tract infection?
A urinary tract infection, also called UTI, refers to a bacterial infection of the bladder (“cystitis”) or the kidneys (“pyelonephritis”).

What causes a urinary tract infection?
A urinary tract infection is caused by bacteria that get into the bladder from the skin surface surrounding the urethra (the opening that urine comes out of). Because of the proximity of the urethra to the colon, organisms like E. coli are common causes of UTI.

How does it cause disease?
Once the bacteria get into the bladder, they can grow in the urine, especially if the child does not empty the bladder frequently, or if there are structural abnormalities of the urinary tract. If the infection of the bladder is not recognized and treated, it can move up the ureters (the tubes that connect the bladder to the kidney) and cause an infection of the kidneys.

Who gets a urinary tract infections?
In the newborn period, both boys and girls get UTI. Boys seem to be at an increased risk if they are uncircumcised with a tight foreskin. Thereafter, UTI is much more common in girls, presumably because they have shorter urethras, leading to more frequent bacterial contamination of the bladder. In girls, itching caused by pinworms, sitting in bathwater for an extended time period, bubble bath, wiping from back to front, and sexual activity increase the likelihood of such bacterial contamination, and thereby increase the risk of UTI. In addition, the bacteria more readily cause infection in those girls who urinate infrequently or incompletely.

What are the common findings?
The symptoms of a urinary tract infection are dependent upon the age of the child. In older children and adults, the symptoms may include a fever and back pain (i.e., a kidney infection), or increased frequency, urgency, or burning on urination (i.e., a bladder infection). Younger children may have enuresis (bed or clothes wetting) or strong smelling urine. Babies and infants often have less specific symptoms, such as a fever, poor feeding, and/or failure to gain weight.

How is a urinary tract infection diagnosed?
Most importantly, a urine specimen must be analyzed to diagnose UTI. The way the specimen is obtained is critical to interpretation. When the child is sick, it is recommended to get a urine specimen by catheter (inserting a thin tube up the urethra into the bladder). Especially in younger children, bag urines, or those obtained by having the child urinate into a cup, often are contaminated, and may confuse the correct diagnosis.
“Clean catch” urine specimens may be useful in boys and older girls who do not have a fever, if obtained by a health professional. The urine should be analyzed immediately or held in the refrigerator. A preliminary “urine analysis” can be performed by dipping a special test strip into the urine; however, it also should be cultured. These results take 24 to 48 hours. Treatment may be started based on the urine analysis.

How is a urinary tract infection treated?
Oral antibiotics, taken for 10 to 14 days, are very effective in the treatment of UTI. Antibiotics can be given at home, unless the child is very young, vomiting, and/or very sick. Once the culture result is known, antibiotics may be changed. Fluids should be encouraged to promote urine flow.
Often, physicians will obtain imaging (e.g., x-rays, ultrasound, or scanning) of the urinary tract in children with UTI. This imaging may help to determine which children require a closer follow-up, or need to see the urologist (a surgeon who specializes in diseases of the urinary tract). Most children with UTI can be cared for very effectively by the primary physician.

What are the complications?
The bacteria that cause a urinary tract infection rarely enter into the bloodstream (“sepsis”). Recurrent kidney infections may cause scarring of the kidneys. However, these complications are more common in children who have significant structural abnormalities of the urinary tract.

How can a urinary tract infection be prevented?
Preventive measures are useful to reduce the recurrence of UTI. Children should be treated for pinworms or constipation, if determined to be present, by a primary physician. Girls should take showers rather than baths, and be taught to wipe from the front to the back (to decrease fecal contamination). Little girls often tend to “hold” their urine, which should be actively discouraged. All children should be encouraged to drink fluids frequently and to urinate every three to four hours (an alarm watch and/or a discussion with the child’s teacher often helps).
The primary physician may suggest follow-up appointments for urine testing, or home follow-up using urine testing strips and urine specimens collected first thing in the morning. Any child with a positive home test (if done) or the symptoms of UTI should see a physician. Some children (especially the very young, those with complications, and those with recurrences) may be put on long-term antibiotic therapy to prevent recurrent infections, but this may result in the development of more resistant organisms.

What research is being done?
Current research is focused on better ways to treat and prevent UTI at home. Physicians also are trying to identify how imaging tests can better guide the management of UTI.

Links to other information
For more information on urinary tract infections, visit: National Kidney and Urologic Diseases Information Clearing House.

References
Todd JK. Prevention of urinary tract infection in children. Report on Ped ID 1997;September:7(8);29-32.
Garin EH, Campos A, et al. Primary vesicoureteral reflux: review of current concepts (in process citation). Pediatr Nephrol 1998;12(3):249-56.
Todd JK. Home follow-up of urinary tract infection. Comparison of two nonculture techniques. Am J Dis Child 1977;131(8):860-1.
Todd JK. Office laboratory diagnosis of urinary tract infection. Pediatr Infect Dis 1982;1:126-131.
Hoberman A, Wald ER. Urinary tract infections in young febrile children. Pediatr Infect Dis J 1997;16(1):11-7.
Hoberman A, Wald ER, Hickey RW, Baskin M, Charron M, Majd M, Kearney DH, Reynolds EA, Ruley J, Janosky JE. Oral versus initial intravenous therapy for urinary tract infections in young febrile children. Pediatrics 1999;104:79-86.
Copyright 2012 James K. Todd, M.D., All Rights Reserved