Medela Waterless Milk Warmer: Liner Change Recommendations

Kathleen Quellen, RN, BSN / January 2023

What is the Medela Waterless Milk Warmer™?

Waterless warming with the Medela Waterless Milk Warmer has been a standard of practice for many years in many hospitals across the United States. Despite being used regularly and frequently, questions still come up about using water, resulting in not all hospitals having made the switch. Additionally, questions about liner changing have been a recent hot topic, with the Joint Commission inquiring why a hospital may change a liner every 24 hours – versus the Medela Instructions for Use recommendation of every 12 hours. We’ve provided answers to these questions, as well as some references and guidelines so healthcare professionals like yourself can be prepared to explain your responses and make your case for getting the water out of warming milk.

Water is always necessary in any hospital setting. However, around medical devices and in some medical circumstances, it can be detrimental to health as it can serve as a reservoir for waterborne organisms. The Medela Waterless Milk Warmer instead uses air moving over a heating element that warms this air to a specific temperature. Once the warming cycle is complete, the air is maintained for up to 30 minutes at body temperature to ensure the milk is not overheated. This helps stabilize temperature variations.

How Does Waterless Warming Align with CDC Recommendations?

The CDC recommends to take water out of the hospital environment whenever possible. The statement below is directly from the CDC and is a great reference material when looking for documentation on using waterless products:

From CDC:  Background D. Water, Guidelines for Environmental Infection Control in Health-Care Facilities, 2003

Modes of Transmission of Waterborne Diseases

Moist environments and aqueous solutions in health-care settings have the potential to serve as reservoirs for waterborne microorganisms. Under favorable environmental circumstances (e.g., warm temperature and the presence of a source of nutrition), many bacterial and some protozoal microorganisms can either proliferate in active growth or remain for long periods in highly stable, environmentally resistant (yet infectious) forms. Modes of transmission for waterborne infections include:

  • direct contact [e.g., that required for hydrotherapy];
  • ingestion of water [e.g., through consuming contaminated ice];
  • indirect-contact transmission [e.g., from an improperly reprocessed medical device];
  • inhalation of aerosols dispersed from water sources; and
  • aspiration of contaminated water.

The first three modes of transmission are commonly associated with infections caused by gram-negative bacteria and nontuberculous mycobacteria (NTM). Aerosols generated from water sources contaminated with Legionella spp. often serve as the vehicle for introducing legionellae to the respiratory tract.

Overall, waterless warming provides a way to accurately warm milk without overheating (and then potentially damaging!) critical milk nutrients, with the water removed from the process.

What are the Liner Change Recommendations for the Waterless Milk Warmer?

The Medela Waterless Milk Warmer must be used with a Medela Disposable Liner to ensure safe handling of human milk. The Disposable Liner is designed to contain spills, maintain hygiene standards, avoid bacterial growth, and prevent cross-contamination between patients.

  • Waterless Milk Warmer Disposable Liners are a limited use item. This means that they are for single-patient use and should be changed every 12 hours.
  • This recommendation is based on feedback gathered from clinicians that stated the expected insert period would be 12 hours or less.
  • If the liner tears or its integrity becomes otherwise compromised, it should be discarded immediately and a new one inserted.
  • Refer to the product's Instructions for Use for complete instructions. 

Milk handling varies greatly among hospitals. In fact, milk administration can vary from shift to shift, as a baby might be made NPO or be fed at the breast and warming milk might not be needed. To ensure proper hygiene standards for your hospital, it is recommended that your hospital refer to its own infection control policy when making decisions on how to handle your waterless warmer and liner changes. Joint Commission surveyors have been questioning hospitals recently about their warmer change policy, specifically the decision to change liners every 24 hours versus every 12 hours. Be prepared and ready with your hospital policy that should already follow your infection control department’s recommendations to ensure clear communication.

If you are trying to reinforce or make a change to waterless warming or if you have any additional questions regarding the use of the Disposable Insert for our Waterless Milk Warmer, reach out to your Medela representative for more information.

About the Author

Kathleen Quellen, RN, BSN, has been a NICU/PICU RN since 1981. She has worked in hospitals all over the U.S., including Georgetown University Hospital, DC Children’s, Cedars Sinai and Children’s Hospital of NJ. She worked as a Clinical Specialist for Abbott Labs/Hospira and has been a NICU Clinical Specialist for Medela LLC since 2014. She covers hospitals all throughout the western United States.

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