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The Preterm Infant, Ototoxic Drugs, and the NICU

February 3, 2014

This update steps a little outside of speech-language pathology’s typical scope, but it is still something that affects us and our clients.

blog_ototoxic-drugs-audicus-hearing-aidsIn 2007 the American Academy of Pediatrics suggested that all infants with increased risk for hearing loss receive hearing screening between 24 and 30 months of age.  One significant risk factor is the use of ototoxic drugs, particularly with premature neonates.  The development of the cochlea occurs relatively late during gestation, as demonstrated by higher frequencies (1000 – 3000 Hz) only being detectable within the womb after about 33 weeks.  When born prematurely, the infant may be exposed to the hearing world before they’re ready; the NICU is noisy and confusing, with sounds from a plethora or machines and people reaching peaks of 120 dBA.  Expectedly, the exposure to such intense sound even occasionally can have long-lasting effects on hearing.

The immune system of premature infants is also not at peak efficiency.  Common in NICU infants is a body-wide septic infection, for which one or a series of broad-spectrum antibiotics will be used.  Aminoglycosides — most commonly the affordable gentamicin — are commonly used for their efficacy against Gram-negative bacteria.  Unfortunately, one of the side-effects of this drug type is toxicity to the auditory nerve.  Animal studies have suggested that children are significantly more prone than adults to ototoxicity of aminoglycosides.

NICU Tour

Although the results in the literature prevent definite conclusions — largely due to variations in dosage, noise levels, and duration — the pairing of noise and ototoxic drugs potentiates the risk to early hearing loss.  Loud noise may in fact directly increase the effects of aminoglycosides:  Louder noises cause mechanoelectrical transduction (MET) to take place in hair cells, opening the cell to the expected electrolyte and also the unexpected ototoxic drug.  The effect is further increased by certain mitochondial mutations, though the prevalence of this in premature infants is not well known.

The implications and recommendations accumulated from the references below are as follows:

  • Create a quieter NICU environment by using silent alarms, sound-level checks, private bed suites, and more.
  • Genetic testing to determine elevated risk to aminoglycoside ototoxicity.
  • Expand the research in aminoglycoside use and safety.
  • Advise regular hearing screening in the first few years of life.

More information on ototoxicity: http://www.asha.org/public/hearing/Ototoxic-Medications/

Recommended resources:

White RD. Designing environments for developmental care. Clin Perinatol 2011; 38:745–749.

White RD. The newborn intensive care unit environment of care: how we got here, where we’re headed, and why. Semin Perinatol 2011; 35:2–7.

Refs:

Joint Committee on infant hearing. Year 2007 position statement: principles and guidelines for early hearing detection and intervention programs. Pediatrics. 2007;120:898–921.

So, T. Y. (2009). Use of Ototoxic Medications in Neonates—The Need for Follow-Up Hearing Test. The Journal of Pediatric Pharmacology and Therapeutics: JPPT14(4), 200.

Zimmerman, E., & Lahav, A. (2012). Ototoxicity in preterm infants: effects of genetics, aminoglycosides, and loud environmental noise. Journal of Perinatology33(1), 3-8.

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One Comment leave one →
  1. February 4, 2014 8:14 pm

    This is very interesting! My daughter Joy was born at 23 weeks last year. Due to modern medicine and prayers she is doing great today. I hemorrhaged at 17 weeks for the first of 4 times because of 100% placenta previa, which turned into placenta accreta (which I believe was caused by 3 prior c-sections). After she came home from 121 days in the NICU, I wrote a memoir called “From Hope To Joy” about my life-threatening
 pregnancy and my daughter’s 4 months in the NICU (with my 3 young sons at 
home), which is now available on both the Amazon and Barnes&Noble websites. It was quite a roller 
coaster that I am certain some of you have been on or are currently riding on. My mission is to provide hope to women struggling with
 high-risk pregnancies, encourage expectant mothers to educate themselves before 
electing cesarean deliveries, provide families of premature babies a realistic 
look at what lies ahead in their NICU journey, and show that miracles can 
happen, and hope can turn into joy.
 Please see my website http://www.micropreemie.net and http://www.facebook.com/jenniferdegl and watch our amazing video of my daughter’s miracle birth and life at: http://www.youtube.com/watch?v=V_hleySg-iU
    
Thank you.

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