The Journal of Pediatrics
Volume 153, Issue 3 , Page 319, September 2008

50 Years Ago in The Journal of Pediatrics:

Studies on the pH of the respiratory tract, i: endotracheal aspirate of the healthy newborn infants

  • Dennis W. Nielson, MD

      Affiliations

    • Pulmonary Division, Department of Pediatrics, University of California San Francisco, San Francisco, California
    • ,
  • Richard D. Bland, MD

      Affiliations

    • Vera Moulton Wall Cardiopulmonary Center, Department of Pediatrics, Stanford University School of Medicine, Stanford, California

Article Outline

 

Jacobs S, Papperman SM. J Pediatr 1958;53:298-302

This study assessed the pH of liquid lining the airways of normal newborn infants, presuming this information would help interpret pH measurements on airway secretions of infants with suspected respiratory infection. Airway secretions were taken at birth and 24 hours later from 43 normal newborn infants by manually inserting a catheter through the mouth into the trachea to suck airway fluid into a DeLee trap. In keeping with the times, neither procedural risks nor parental consent were cited in the article. The pH of endotracheal aspirates at birth averaged 7.76 and decreased to 7.45 24 hours later. Cultures of airway secretions taken at birth from 12 (28%) infants grew organisms, compared with 7 positive cultures (17%) obtained after 24 hours. Bacterial contamination did not alter the pH of endotracheal aspirates.

Nearly half a century later a similar study showed greater alkalinity of tracheal aspirates obtained from mechanically ventilated preterm (pH 8.31 ± 0.35) compared with term infants (7.83 ± 0.39), with progressive lowering of aspirate pH (6.89 ± 0.77) during prolonged mechanical ventilation.1 As other studies using electrodes placed directly into the lower airways of children showed pH values that averaged 7.1,2 measurements reported for both term and preterm newborns probably were affected by contaminating upper airway secretions and CO2 loss, yielding artifactual alkalinity. Thus, the significance of these data remains unclear.

Recent studies increased our understanding of how acid-base balance in airway surface liquid (ASL) is regulated via well-defined ion transport mechanisms, perhaps modified by secretory products of airway submucosal glands and goblet cells.3 There is compelling evidence that the pH of ASL can affect ciliary beat frequency, mucous hydration, and bronchial smooth muscle tone. Other studies indicate that defective regulation of acid-base balance in the airways may play an important role in the pathogenesis of cystic fibrosis.4, 5, 6 The impact of ASL pH on respiratory function in other childhood breathing disorders, such as aspiration syndromes and bronchial asthma, warrants further inquiry. We hope to know more in 2058!

Back to Article Outline

References 

  1. Paget-Brown AO, Hunt JF, Gaston B. Tracheal aspirate pH is alkaline in pre-term human infants. Eur Respir J. 2007;30:840–842
  2. McShane D, Davies JC, Davies MG, Bush A, Geddes DM, Alton EWFW. Airway surface pH in subjects with cystic fibrosis. Eur Respir J. 2003;21:37–42
  3. Inglis SK, Wilson SM, Olver RE. Secretion of acid and base equivalents by intact distal airways. Am J Physiol Lung Cell Mol Physiol. 2003;284:L855–L862
  4. Quinton PM. The neglected ion: HCO3−. Nature Med. 2001;7:292–293
  5. Coakley RD, Grubb BR, Paradiso AM, Gatzy JT, Johnson LG, Kreda SM, et al. Abnormal surface liquid pH regulation by cultured cystic fibrosis bronchial epithelium. Proc Natl Natl Acad Sci U S A. 2003;100:16083–16088
  6. Song Y, Salinas D, Nielson DW, Verkman AS. Hyperacidity of secreted fluid from submucosal glands in early cystic fibrosis. Am J Physiol Cell Physiol. 2006;290:C741–C749

PII: S0022-3476(08)00230-8

doi:10.1016/j.jpeds.2008.03.039

The Journal of Pediatrics
Volume 153, Issue 3 , Page 319, September 2008

Article Tools