Transient Tachypnea of the Newborn
last authored: July 2010, Amanda Li
last reviewed:
Introduction
Transient Tachypnea of the Newborn (TTN) describes signs of mild respiratory distress presenting in the first few hours of life. It is caused by delayed clearance of fetal lung fluid, resulting in transient pulmonary edema. Incidence is 5 per 1000 term neonates.
The Case of...
A term baby boy is delivered to a healthy 33 year-old G2P1 by repeat elective caesarian section. GBS status is negative, membranes were ruptured at delivery, and amniotic fluid was clear. He is vigorous at birth and requires no resuscitative measures, but by 10 minutes of age, he is making grunting noises with each breath. Pulse oximeter shows O2 sats between 85-93%.
(Part II) Baby received routine newborn care and careful observation. Over the following two hours, the respiratory symptoms diminished to quiet, non-distressed breathing and intermittent spells of tachypnea to 70-80 breaths per minute maintaining O2 sats >93%. At 24 hours of age, respiratory rate settled 50 breaths per minute, with a normal physical examination.
Causes and Risk Factors
Risk Factors:
- Caesarian section
- short labour or precipitous delivery
- prematurity
- infants of diabetic mothers
- infants of mothers with asthma
Pathophysiology
Clearance of fetal lung fluid begins in the intrapartum period in utero. Hormones and catecholamines released in the days leading up to birth inhibit production of fluid in the lung. Upon birth, resorption of the fluid is mediated by an oncotic pressure gradient between the air spaces, interstitium, and vessels. Active transport of sodium out of the air spaces also promotes fluid clearance into the circulation and lymphatics.
Signs and Symptoms
- history
- physical exam
History
History should focus on risk factors, as described above.
Physical Exam
Examination may reveal:
- tachycardia
- tachypnea
- increased work of breathing (abdominal retractions and nasal flaring)
- good air entry, but diffuse transmitted sounds
Investigations
Begin with monitoring of vitals and oxygen saturation. If non-resolving clinical course or complicating factors present, may consider work up for other causes of respiratory distress:
- cardiopulmonary monitoring
- septic work-up: CBC + diff, CRP, blood cultures, glucose
- chest X-ray
Differential Diagnosis
The differential diagnosis includes:
- Sepsis
- pneumonia
- pneumothorax
- Respiratory Distress Syndrome (RDS)
- congenital lung abnormality
- congenital diaphragmatic hernia
- congenital heart defect
Treatments
No intervention is usually required; however, hypoxia should be avoided to prevent an increase in pulmonary vascular resistance and the development of persistent pulmonary hypertension.
When indicated:
- supplemental O2
- positive pressure respiratory support, eg. continuous positive airway pressure (CPAP)
- IV antibiotics to cover possible sepsis
Consequences and Course
Classic TTN is benign, self-limiting, and resolves over 24 hours, though symptoms occasionally persist to 72 hours.
Resources and References
Demissie, K, Marcella, SW, Breckenridge, MB, Rhoads, GG. Maternal asthma and transient tachypnea of the newborn. Pediatrics 1998; 102:84 Kirpalani, H., Moore, A. M., and Perlman, M. (2007).
Residents Handbook of Neonatology, 3rd Ed., B. C. Decker, Inc., Hamilton, Ont.; 143-144.
Persson, B, Hanson, U. Neonatal morbidities in gestational diabetes mellitus. Diabetes Care 1998; 21 Suppl 2:B79. Taeusch, H. W., & Ballard, R. A. (1998).
Avery’s Disease of the Newborn, 7th Ed. W. B. Saunders Co., Philadelphia, Penn.; 613-615.
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