A drop in gas temperature in the external part of the endotracheal tube is problematic during neonatal respiratory support

Yasumasa Yamada, Teruo Kyuno, Satoshi Suzuki, Tetsuya Ito, Ineko Kato, Hajime Togari

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11 Citations (Scopus)


During neonatal respiratory support, maintaining optimal humidity minimizes the risk of airway occlusion and chronic lung disease. With neonatal respiratory support using a heated humidifier,condensation following decreases in temperature within the unheated part of the inspiratory circuit represents a serious problem, due to the resulting drop in absolute humidity. Several reports describing the temperature/humidity gradient in the unheated inspiratory limb have excluded the endotracheal tube (ETT). The present study investigated the extent to which the temperature gradient in the ETT affects breathing gas conditioning in premature infants, who display tiny minute volumes. By measuring temperature/dew point at various sites along the inspiratory circuit, including inside the ETT, we evaluated the effects of temperature change in the ETT using an in vitro model of a micropremie on mechanical respirator care in an incubator. We confirmed significant moisture loss (absolute humidity loss; 7.5-10.1 mg/L) with decreasing gas temperature in the ETT external to the body, with subsequent drying of the gas (relative humidity drop, 10.7-22.3%) as temperature increased in the ETT inside the body. The present results suggest that temperature decreases in the ETT represent an important issue in the respiratory care of very premature infants.

Original languageEnglish
Pages (from-to)666-673
Number of pages8
JournalPediatric Pulmonology
Issue number7
Publication statusPublished - 01-07-2008
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Pediatrics, Perinatology, and Child Health
  • Pulmonary and Respiratory Medicine

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