Transient tachypnea of the newborn (TTN) is usually benign and improves within 72 hours. However, it can also progress to prolonged tachypnea over 72 hours, profound hypoxemia, respiratory failure, and even death. The aim of this study is to find predictable risk factors and describe the clinical courses and outcomes of prolonged TTN (PTTN).

The medical records of 107 newborns, >35⁺⁰ weeks of gestational age with TTN, who were admitted to the NICU at Seoul Asan Medical Center from January 2001 to September 2007 were reviewed. They were divided into 2 groups based on duration of tachypnea. PTTN was defined as tachypnea ≥72 hours of age, and simple TTN (STTN) as tachypnea <72 hours of age. We randomly selected 126 healthy-term newborns as controls. We evaluated neonatal and maternal demographic findings, and various clinical factors.

Fifty-five infants (51%) with total TTN were PTTN. PTTN infants had grunting, tachypnea >90/min, FiO₂ >0.4, and required ventilator care more frequently than STTN infants. PTTN had lower level of serum total protein and albumin than STTN. The independent predictable risk factors for PTTN were grunting, maximal respiration rate >90/min, and FiO₂ >0.4 within 6 hours of life.

When a newborn has grunting, respiration rate >90/min, and oxygen requirement >0.4 of FiO₂ within 6 hours of life, the infant is at high risk of having persistent tachypnea ≥72 hours. We need further study to find the way to reduce PTTN.