INTRODUCTION:

Transient tachypnea of the newborn (TTN) is a parenchymal lung disorder characterized by pulmonary edema resulting from delayed resorption and clearance of fetal alveolar fluid. TTN is a common cause of respiratory distress in the immediate newborn period. In a review of 33,289 term deliveries (37 to 42 weeks), the incidence of TTN was 5.7 per 1000 births. Although thought to be a benign, self-limited condition, there are increasing data to suggest that TTN increases a newborn's risk for developing a wheezing syndrome early in life.

Transient tachypnea of the newborn (TTN, TTNB, or "transitory tachypnea of newborn") is a respiratory problem that can be seen in the newborn shortly after delivery. Amongst causes of respiratory distress in term neonates, it is the most common.

It consists of a period of rapid breathing (higher than the normal range of 40-60 times per minute). It is likely due to retained lung fluid, and is most often seen in 35+ week gestation babies who are delivered by caesarian section without labor. Usually, this condition resolves over 24–48 hours.

Postnatal respiratory complications among term infants are common. The most commonly reported cause of neonatal respiratory distress is transient tachypnea of the newborn (TTN), with an estimated incidence of 1% to2% of all newborns. The disorder is reported to be benign and self-limiting, with resolution usually occurring by 2to 5 days of age. Known risk factors for TTN include lower gestational age (GA) and birth weight, male gender, and elective cesarean section (ECS).In recent decades, the rates of cesarean section (CS), especially those performed electively at term and partly at maternal request, have shown an increasing trend.

Before birth, a fetus' lungs are filled with fluid. While inside the mother, a fetus does not use the lungs to breathe all oxygen comes from the blood vessels of the placenta.

As the due date nears, the baby's lungs begin to clear the fluid in response to hormonal changes. Some fluid may also be squeezed out during the birth, as a baby passes through the birth canal. After the birth, as a newborn takes those first breaths, the lungs fill with air and more fluid is pushed out of the lungs. Any remaining fluid is then coughed out or gradually absorbed into the body through the bloodstream and lymphatic system. As the baby grows in the womb, the lungs make a special fluid. This fluid fills the developing baby's lungs and helps them grow. When the baby is born at term, chemicals released during labor tell the lungs to stop making this special fluid. The baby's lungs start removing or reabsorbing it. The first few breaths your baby takes after delivery fill the lungs with air and help to clear most of the remaining lung fluid. Leftover fluid in the lungs causes the baby to breathe rapidly and makes it harder for the baby to keep the small air sacs of the lungs open.

In infants with TTN, however, extra fluid in the lungs remains or the fluid is cleared too slowly. So it is more difficult for the baby to inhale oxygen properly, and the baby breathes faster and harder to get enough oxygen into the lungs. Due to the higher incidence of TTN in newborns delivered by caesarean section, it has been postulated that TTN could result from a delayed absorption of fetal lung fluid from the pulmonary lymphatic system. The increased fluid in the lungs leads to increased airway resistance and reduced lung compliance. It is thought this could be from lower levels of circulating catecholamine’s after a caesarean section, which are believed to be necessary to alter the function of the ENaC channel to absorb excess fluid from the lungs.

Medical care of transient tachypnea of the newborn (TTN) is supportive. As the retained lung fluid is absorbed by the infant's lymphatic system, the pulmonary status improves. Supportive care includes intravenous fluids and gavages feedings until the respiratory rate has decreased enough to allow oral feedings. Supplemental oxygen to maintain adequate arterial oxygen saturation, maintenance of thermo neutrality, and an environment of minimal stimulation are the therapies necessary in these infants. ABG assessments should be periodically repeated, especially if the infant's condition worsens. Similarly, chest radiography should be repeated if clinical decomposition is observed. As transient tachypnea of the newborn resolves, the infant's tachypnea improves, oxygen requirement decreases, and chest radiography shows resolution of the peripheral streaking. Infants with transient tachypnea of the newborn may have signs that last from a few hours to several days. Rarely, an infant develops a worsening picture of respiratory distress after several days. This may require more aggressive support including the use of continuous positive airway pressure (CPAP) or mechanical ventilation.

OVERVIEW:

Definition:

Transient tachypnea of the newborn (TTN) is a term for a mild respiratory problem of babies that begins after birth and lasts about three days:

"Transient" means temporary

"Tachypnea" means fast breathing rate

Transient tachypnea is a very fast breathing rate. It happens in newborns that have too much fluid in their lungs. The fluid limits the amount of oxygen these newborns pull into their lungs. As a result, the baby needs to breathe at a faster rate to get enough oxygen.Babies born with this condition usually recover within three days of birth. (fig1)

Fig: 1 Respiratory System of an Infant

Alternative names: Other names for transitory tachypnea include:

Ø TTN

Ø Wet lungs-newborns

Ø Retained fetal lung fluid

Ø Transient RDS

Ø Prolonged transition

Ø Type II respiratory distress syndrome

Pathophysiology:

During Vaginal births, especially with full-term babies, the pressure of passing through the birth canal squeezes some of the fluid out of the lungs. Hormonal changes and physical pressure during labor may also lead to absorption and push out of some of the fluid.

Babies who are small or premature or who are delivered via rapid vaginal deliveries or C-section don't undergo the usual squeezing and hormone changes of a vaginal birth. So they tend to have more fluid than normal in their lungs when they take their first breaths. After birth, the baby may also cough some of the fluid out of the lungs. The baby's first breaths should clear out any remaining fluid. Some newborns are not able to clear enough fluid from their lungs. The fluid blocks some oxygen from moving from the lungs to the blood (fig: 2).

The low level of oxygen causes transient tachypnea, Fluid might not clear from lungs quickly enough if:

Ø The baby doesn’t respond well to the chemical signals during labor

Ø Fluid isn’t squeezed out of the lungs in the birth canal

This condition typically causes a fast breathing rate (tachypnea) for the infant. While the symptoms may be distressing, they are typically not life-threatening. In fact, symptoms are transitory (short-lived), usually disappearing within one to three days after birth.

Passive reabsorption of liquid also occurs after birth because of differences among the oncotic pressure of air spaces, interstitial, and blood vessels. The majority of water transport across the apical membrane is thought to occur through aquaporin 5 (AQP5) water channels. Delayed reabsorption of fetal lung fluid is thought to be the underlying cause of TTN. Fluid fills the air spaces and moves into the interstitial, where it pools in perivascular tissues and interloper fissures until it is eventually cleared by the lymphatic or absorbed into small blood vessels. The excess lung water in TTN results in decreased pulmonary compliance.

Tachypnea develops to compensate for the increased work of breathing associated with reduced compliance. In addition, accumulation of fluid in the peribronchiolar lymphatics and interstitial promotes partial collapse of the bronchioles with subsequent air trapping. Continued perfusion of poorly ventilated alveoli leads to hypoxemia, and alveolar edema reduces ventilation, sometimes resulting in hypercapnia. In one study, the expression of AQP5 was greater in patients with TTN than those with respiratory distress syndrome or controls. This finding suggests that up regulation of AQP5 increases reabsorption of postnatal lung fluid, which contributes to the quick resolution of symptoms in infants with TTN

Risk Factors and Causes:

Factors that may increase your baby’s chance of developing transient tachypnea include:

ü Delayed cord clamping

ü Rapid vaginal delivery

ü Excess maternal fluid administration

ü Sex: male

ü Both preemies (because their lungs are not yet fully developed) and full-term babies.

ü delivered by cesarean section (C-section)

ü born to mothers with diabetes

ü born to mothers with asthma

ü small for gestational age (small at birth)

Sign/symptoms of TTN include:

o Rapid, labored breathing (tachypnea) of more than 60 breaths a minute

o Grunting or moaning sounds when the baby exhales

o Flaring nostrils or head bobbing

o Retractions (when the skin pulls in between the ribs or under the ribcage during rapid or labored breathing)

o Cyanosis (when the skin turns a bluish color) around the mouth and nose

o Other than the above symptoms, infants with ttn will look fairly healthy

Diagnostic test:

TTN has symptoms that are initially similar to more severe newborn respiratory problems the following diagnostic test will help out to make diagnosis;

· The mother’s pregnancy and labor history are important (refer high risk and cause)

· Physical examination of newborn(refer signs and symptoms)

Other indicators used to make a diagnosis of TTN:

Chest x ray: If an infant has TTN, the X-ray picture of the lungs will appear streaked and fluid may be seen (fig: 3). The X-ray will otherwise appear fairly normal.

Fig:3 chest x ray of neworn with TTN

Ø Pulse-oximetry monitoring: This tells how well the lungs are sending oxygen to the blood and is also useful in monitoring TTN. Sometimes oxygen levels need to be checked with a blood test.

Ø A complete blood count (CBC) may also be drawn from one of the baby's veins or a heel to check for signs of infection

Transient tachypnea is usually diagnosed after the baby is monitored for 1 or 2 days

Differential diagnoses:

ü Congenital heart disease

ü Neonatal Pneumonia

ü Aspiration

ü Meconium Aspiration

ü Persistent Fetal Circulation

Treatment:

Supplemental oxygen-

As with any newborn that has a breathing problem, infants with TTN is closely watched. Sometimes they'll be admitted to the neonatal for extra care. Monitors will measure heart rate, breathing rate, and oxygen levels.

Oxygen may be given through a mask, a tube that passes under the nose, or a tent. This extra oxygen will lower the workload on the lungs.

Continuous positive airway pressure (CPAP) –

If a baby is still struggling to breathe, even when oxygen is given, continuous positive airway pressure (CPAP) might be used to keep air flowing through the lungs. With CPAP, a baby wears a special oxygen cannula (a type of tubing placed directly into the nose) and a machine continuously pushes a stream of pressurized air into the baby's nose to help keep the lungs open during breathing.

Intravenous (IV) Fluids:

Provide hydration and will prevent the infant's blood sugar from dipping to dangerously low levels. If baby has TTN and you want to breastfeed, consult your doctor or a nurse about maintaining your milk supply by using a breast pump while your infant receives IV fluids.

Within 24 to 48 hours, the breathing of infants with TTN usually improves and returns to normal, and within 72 hours, all symptoms of TTN end.

Supplemental feedings-

It can be difficult for a baby to nurse when he/she has breathing problems. An IV line may be used to delivers fluids, glucose, and electrolytes.

Ventilator support-

A ventilator may be used if a baby is really struggling to breath. This machine will help or take over breathing for the baby. In the most severe cases of TTN, a baby would need ventilator support, but this is rare. Nutrition can be a problem if an infant is breathing so fast that he or she can't suck, swallow, and breathe simultaneously. In that case,

Antibiotics-

Intravenous (IV) antibiotics may be given until test results are back. The antibiotic will be stopped if the tests do not show an infection.

The main treatment for this condition is supportive care and close monitoring. This may include:

A day or two after birth, the baby’s breathing should improve. By the third day of life, all symptoms of transient tachypnea should disappear

Specific treatment for transient tachypnea of the newborn will be determined by based on:

v Baby’s gestational age, overall health, and medical history

v Extent of the condition

v Baby’s tolerance for specific medications, procedures, or therapies

v Expectations for the course of the condition

v Parent’s opinion or preference

Prognosis:

1. After babies with TTN receive special monitoring and treatment in the hospital, they usually recover fully. Even after TTN resolves, watch for signs of respiratory distress and consult neonatologist if you suspect a problem.

2. If baby has trouble breathing, appears blue, or if the skin pulls in between the ribs or under the ribcage during rapid or labored breathing, call you neonatologist or emergency services right away.

3. The condition usually goes away within 24 - 48 hours after delivery. Babies who have had transient tachypnea usually have no further problems from the condition, and do not need special care or follow-up other than their routine pediatrician visits.

Prevention:

There are no guidelines for preventing transient tachypnea because the exact cause is not known. There are several things you can do to help give birth to a healthy baby:

ü Eat a healthful diet. Aim for a diet low in saturated fats and rich in whole grains, fruits, and vegetables.

ü Have regular prenatal check-ups.

ü Don’t smoke. If you smoke, quit.

ü Avoid drugs and alcohol.

REFERENCES:

1. Dudell GG, Stoll BJ. Respiratory tract disorders. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds.Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 95.

2. Kimberly G Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., and Inc.

3. Blickman JG, Parker BR, Barnes PD. Pediatric radiology, the requisites. Mosby Inc. (2009) ISBN: 0323031250. Read it at Google Books - Find it at Amazon

4. Horbar JD, Badger GJ, Carpenter JH, Fanaroff AA, Kilpatrick S, LaCorte M, et al., Members of the Vermont Oxford Network. Trends in mortality and morbidity for very low birth weight infants, 1991–1999. Pediatrics. 2002;1101 pt 1143–51.

5. http://kidshealth.org/parent/medical/lungs/ttn.html#a_About_TTN

6. Kasap B, Duman N, Ozer E, Tatli M, Kumral A, Ozkan H. Transient tachypnea of the newborn: predictive factor for prolonged tachypnea. Pediatr Int. Feb 2008;50(1):81-4. [Medline].

7. Rawlings JS, Smith FR. Transient tachypnea of the newborn. An analysis of neonatal and obstetric risk factors. Am J Dis Child. Sep 1984;138(9):869-71. [Medline].

8. Riskin A, Abend-Weinger M, Riskin-Mashiah S. Cesarean section, gestational age, and transient tachypnea of the newborn: timing is the key. Am J Perinatol. Oct 2005; 22(7):377-82.

9. Takaya A, Igarashi M, Nakajima M, Miyake H, Shima Y, Suzuki S. Risk factors for transient tachypnea of the newborn in infants delivered vaginally at 37 weeks or later. J Nippon Med Sch. Oct 2008; 75(5):269-73. [Medline].

10. Yurdakok M. Transient tachypnea of the newborn: what is new?. J Matern Fetal Neonatal Med. Oct 2010; 23 Suppl 3:24-6. [Medline].

11. Hermansen CL, Lorah KN. Respiratory distress in the newborn. Am Fam Physician. Oct 1 2007; 76(7):987-94. [Medline].

12. Whitsett JA, Pryhuber GS, Rice WR. Acute respiratory disorders. In: Avery GB, Fletcher MA, and MacDonald MG, eds. Neonatology: Pathophysiology and Management of the Newborn. 4th ed. Philadelphia, Pa: Lippincott-Raven; 1994:429-52.

13. Miller MJ, Fanaroff AA, Martin RJ. Respiratory disorders in preterm and term infants. In: Fanaroff AA, Martin RJ, eds. Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant. 6th ed. St Louis, Mo: Mosby-Year Book; 1997:1040-65.

14. Shaw D. The chest. In: Carty H, Shaw D, Brunelle F, Kendall B, eds. Imaging children. Edinburgh: Churchill Livingstone; 1994:1-165. Kuhn JP, Fletcher BD, DeLemos RA. Roentgen findings in transient tachypnea of the newborn. Radiology. Mar 1969; 92(4):751-7.

Received on 24.11.2013 Modified on 12.01.2014

Int. J. Nur. Edu. and Research 2(2): April- June 2014; Page 99-103