Basics
Description
- Early onset of tachypnea (respiratory rate >60 breaths/minute) in the newborn following an uneventful delivery
- Symptoms of respiratory distress including mild retractions, expiratory grunting, and nasal flaring may occur. Cyanosis is rarely involved.
Epidemiology
Incidence
- Estimated 4 " “6 per 1,000 live births
- Incidence is likely underestimated.
- Most common cause of respiratory distress in newborns
- Higher in males
Risk Factors
- Early gestation
- Cesarean section delivery (with or without preceding labor)
- Male gender
- Maternal diabetes
- Macrosomia
- Low birth weight
- Maternal history of asthma
- Unexplained transient tachypnea of the newborn (TTN) in individuals belonging to the same family suggests a genetic predisposition.
General Prevention
- Vaginal delivery should be recommended in the absence of maternal or fetal indications for cesarean section.
- Elective cesarean section before 39 weeks ' gestation should be avoided.
Etiology
- During fetal life, pulmonary epithelial cells are secretory, delivering chloride into the alveolar space.
- Sodium and water follow chloride into the alveoli, establishing and maintaining fetal lung fluid.
- During labor and delivery, fetal lung fluid is absorbed through a variety of proposed mechanisms:
- Epithelial cells transition from secretory cells to absorptive cells in response to circulating epinephrine levels, which trigger opening of epithelial sodium channels (ENaC).
- Compression of the fetal thorax from uterine contractions and passage through the vaginal canal contributes to removal of fluid from the lungs through the pulmonary circulation.
- Prostaglandin-mediated dilation of lymphatic vessels occurs with resultant absorption of interstitial lung fluid into the lymphatic system.
- TTN occurs when there is inadequate fluid clearance from the lungs.
- It is believed that this excess interstitial lung fluid contributes to decreased lung compliance.
Diagnosis
History
- Tachypnea presenting within the first few hours of life
- Presence of familial risk factors
- Maternal diabetes
- Maternal asthma
- Family history of unexplained TTN
- Birth-related risk factors
- Absence of risk factors that suggest an infectious, metabolic, or anatomic disease process such as the following:
- Maternal chorioamnionitis or other untreated maternal infections
- Meconium or blood-stained amniotic fluid
- Prolonged rupture of membranes
- Long-standing oligohydramnios or anhydramnios
- Advanced resuscitation at delivery
- Presence of risk factors for other conditions should prompt additional investigations.
Physical Exam
- Respiratory rate >60 breaths/minute
- Grunting, nasal flaring, mild to moderate retractions; rarely, cyanosis
- Symmetric breath sounds on auscultation
- Symmetry of thoracic cavity, possibly with barrel-shaped chest appearance due to lung hyperinflation
- Lungs are generally clear on auscultation, but crackles may be present.
- Absence of stridor
- Absence of signs, symptoms, or other abnormalities in one or more additional organ systems
Diagnostic Tests & Interpretation
- TTN is a diagnosis of exclusion.
- Degree of diagnostic workup will vary and will depend on risk factors and clinical manifestations of the mother and baby.
- Risk factors or physical findings consistent with other disease processes should prompt diagnostic testing as clinically indicated.
- CBC
- Leukopenia or leukocytosis with increased immature to total neutrophil count suggests infection.
- C-reactive protein
- May be elevated within the first 24 hours with infectious etiology
- If abnormalities exist on these laboratory evaluations, a workup for infection is warranted and should minimally include a blood culture and chest radiograph.
- Arterial blood gas
- Respiratory acidosis (particularly for Pco2 >60 mmHg), metabolic acidosis, or metabolic alkalosis suggest alternative etiologies for respiratory distress.
- A significantly elevated A " “a gradient may suggest an extrapulmonary or intrapulmonary right-to-left shunt.
- Pulse oximetry
- Typically, preductal saturations will be greater than 95% on room air.
- Supplemental oxygen is rarely required; oxygen supplementation of more than 40% FiO2 suggests an alternative etiology.
- Echocardiogram
- Respiratory distress and cyanosis may be a manifestation of congenital heart disease.
Imaging
- Chest radiograph
- Findings are variable but generally include pronounced perihilar vascular marking and fluid opacity in the interlobar spaces.
- Slight flattening of the diaphragms and increase in the intercostals spaces can be present if air trapping occurs.
- Of note, there may be poor concordance between the clinical diagnosis of TTN and the presence of radiographic findings of TTN, as radiographic interpretation in cases of TTN is relatively variable.
Differential Diagnosis
- Respiratory
- Delayed adaption of the newborn
- Meconium/blood/amniotic fluid aspiration
- Respiratory distress syndrome
- Pulmonary hypoplasia
- Persistent pulmonary hypertension of the newborn
- Pneumothorax
- Pneumomediastinum
- Infection
- Neurologic
- Hypoxic brain injury
- Conditions that present with central hypotonia
- Cardiac
- Congenital cyanotic heart disease
- Cardiovascular anatomy that contributes to pulmonary overcirculation
- Metabolic
- Conditions that present with metabolic acidosis or hyperammonemia
- Miscellaneous
- Disorders related to abnormal embryonic pulmonary development (e.g., congenital diaphragmatic hernia, congenital cystic adenomatous malformation, congenital emphysema)
- Congenital airway abnormalities (e.g., Pierre Robin sequence, choanal atresia)
Alert
TTN is a diagnosis of exclusion. A thorough review of the maternal history, birth history, and physical examination is essential in determining the degree of workup needed to exclude more severe etiologies. ‚
Treatment
General Measures
- Resolution of symptoms will occur in time, most often within the first 2 days of life.
- Initial management
- Direct observation under radiant heat for signs of worsening tachypnea/distress or other abnormal vital signs
- NPO for initial observation period
- Monitoring for hypoglycemia
- Continuous cardiorespiratory monitoring and pulse oximeter monitoring " ”preductal saturation goal of >95% as the infant transitions to extrauterine circulation
- Administration of antibiotics and appropriate diagnostic workup if infection or metabolic condition is suspected
Ongoing Care
Follow-up Recommendations
Patient Monitoring
- Admission to a Special Care Nursery or Neonatal Intensive Care Unit and chest radiography are indicated for the following:
- Symptoms persisting beyond 2 hours from onset
- Worsening of symptoms or onset of additional symptoms
- Infection is suspected.
- Persistent need for oxygen
- Chest radiograph is abnormal.
- IV fluids are required to maintain nutrition/hydration.
Patient Education
Infant can transition to routine care when ‚
- There has been steady improvement in symptoms during the observation period.
- The respiratory rate permits adequate oral nutrition.
- When oxygen is no longer required to maintain normal oxygen saturations
Prognosis
- TTN is typically self-resolved and few, if any, long-term sequelae exist.
- Recent studies have shown an association between TTN and developing wheezing symptoms at school age.
Complications
- Hypoxia requiring oxygen administration
- Occasionally, mechanical ventilation is necessary, and rarely, extracorporeal membrane oxygenation is needed if persistent pulmonary hypertension develops.
Additional Reading
- Abughalwa ‚ M, Taha ‚ S, Sharaf ‚ N, et al. Antibiotics therapy in classic transient tachypnea of the newborn: a necessary treatment or not? A prospective study. Neonatology Today. 2010;7(6):3 " “8.
- American College of Obstetricians and ‚ Gynecologists. ACOG Committee opinion no. 559: cesarean delivery on maternal request. Obstet Gynecol. 2013:121(4);904 " “907. ‚ [View Abstract]
- Consortium on Safe ‚ Labor, Hibbard ‚ JU, Wilkins ‚ I, et al. Respiratory morbidity in late preterm births. JAMA. 2010;304(4):419 " “425. ‚ [View Abstract]
- Costa ‚ S, Rocha ‚ G, Leit ƒ £o ‚ A, et al. Transient tachypnea of the newborn and congenital pneumonia: a comparative study. J Matern Fetal Neonatal Med. 2012:25(7):992 " “994. ‚ [View Abstract]
- Guglani ‚ LG, Lakshminrusimha ‚ S, Ryan ‚ R. Transient tachypnea of the newborn. Pediatr Rev. 2008;29(11):e59 " “e65. ‚ [View Abstract]
- Hermansen ‚ CL, Lorah ‚ KN. Respiratory distress in the newborn. Am Fam Physician. 2007:76(7):987 " “994. ‚ [View Abstract]
- Liem ‚ JJ, Hug ‚ SI, Ekuma ‚ O, et al. Transient tachypnea of the newborn may be an early clinical manifestation of wheezing symptoms. J Pediatr. 2001:151(1):29 " “33. ‚ [View Abstract]
- Mendola ‚ P, M ƒ ¤nniat ƒ ¶ ‚ TI, Leishear ‚ K, et al. Neonatal health of infants born to mothers with asthma. J Allergy Clin Immunol. 2014;133(1):85 " “90. ‚ [View Abstract]
- Silasi ‚ M, Coonrod ‚ DV, Kim ‚ M, et al. Transient tachypnea of the newborn: is labor prior to cesarean delivery protective? Am J Perinatol. 2010:27(10):797 " “802. ‚ [View Abstract]
- Yurdakok ‚ M. Transient tachypnea of the newborn: what is new? J Matern Fetal Neonatal Med. 2010;23(Suppl 3):24 " “26. ‚ [View Abstract]
Codes
ICD09
- 770.6 Transitory tachypnea of newborn
ICD10
- P22.1 Transient tachypnea of newborn
SNOMED
- 7550008 Transitory tachypnea of newborn (disorder)
- 276531000 Avery 's syndrome type 1 (disorder)
- 276532007 Avery 's syndrome type 2 (disorder)
FAQ
- Q: For how long does the tachypnea generally occur?
- A: Most babies ' respiratory rates improve within 72 hours; in persistent cases, it may last longer.
- Q: What respiratory rate is safe for trial of PO feeds?
- A: <70 breaths/minute without an exaggerated respiratory effort.
- Q: What respiratory rate is safe for hospital discharge?
- A: <60 breaths/minute for greater than 12 hours to ensure resolution of symptoms and confirm the diagnosis of TTN.