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Managing body temperature: using a forced air warming device – 3M Bair Hugger® 775

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Forced air warming blankets are a commonly used medical device in the perioperative setting and within Paediatric Intensive Care and High Dependency units They are used as a means of preventing inadvertent hypothermia during prolonged operative procedures, and to help establish and maintain normothermia in acutely and critically ill infants and children.

This nursing procedural guideline is intended as a resource for nursing staff in the Paediatric Critical Care Unit at the Royal Hospital for Children (Glasgow) involved in caring for children that require body temperature management and forced air warming to prevent hypothermia. The guideline has been constructed after a literature search and review of sourced textbooks, manufacturer guidelines and recommendations, Medline and CINHAL, and external nurse expert peer review and opinion. See also recommendations and further information at end of this guideline.


This nursing procedural guideline is intended to be followed by nurses involved in caring for the highly dependent or critically ill infant or child requiring body temperature management and prevention of hypothermia using forced air warming within the Paediatric Critical Care Unit at RHC (Glasgow).


All nursing staff involved in the management of body temperature and use of forced air warming in the Paediatric Critical Care Unit should be familiar with this nursing procedural guideline.

  • 3M Bair Hugger® 775 warming unit
  • Bair Hugger® disposable warming blanket – appropriate size
  • Cotton blanket or sheet(s)
  • Disposable apron



Provide age explanation of equipment and procedure to child (and parents) where appropriate.

To ensure the child (and parents) understand the reason for active warming.

Gather equipment together and wash hands. Don disposable apron.

To minimise risk of cross infection.

Check that the infant or child’s skin is as dry as possible before putting forced air warming blanket on.

Air flow over moist skin may cause initial cooling due to evaporation.

Before initiating therapy, check unit is free from any obvious mechanical damage and is safely placed on a hard surface (NOT a bed/mattress*) or securely mounted (Fig1&2)

Fig. 1

Injury may result if a faulty unit used or if not secured on stable surface* or secured to pole.

 Fig. 2

* a bed/mattress surface is uneven and may result in air being blocked and unit to overheat. 


Check unit, ensure the air hose is intact and secure at side port of unit (Fig. 3), then plug in to a properly grounded power source (Do not switch ON yet).


Fig. 3

Place the Bair Hugger® forced-air blanket (correct size) directly onto the infant or child with the perforated side against the infant or child’s skin (Fig. 4).

Fig. 4

Thermal injury may result if any cover or forced-air blanket other than Bair Hugger® used.

The slits in the perforated side allow the warm air to surround the infant or child. Placing a blanket or sheet between the infant/child and the forced-air blanket will result in warming being impeded.

Placing the plastic cover side of the forced-air blanket instead of the perforated side will impede warming and (if high temperature setting) may even result in skin injury.

Insert the end of the air hose into the cardboard connector (Fig. 5) on the forced-air warming blanket until it fits snugly. 
Use a twisting motion to ensure a snug fit. 

 Fig. 5

A visual marker (Fig. 6) is located around the mid section of the hose to guide the depth of the hose insertion.

 Fig. 6


Significant thermal injury may occur if the air hose is not attached correctly to the blanket. 


Do not "free hose" - i.e. blow warm air onto the infant or child without the blanket being connected.

Once the Bair Hugger® is on, a cotton blanket or sheet may be placed on top of the forced-air blanket.

This will help minimize heat loss from the system and keep the forced-air blanket centered on the infant or child.

Press system ON/OFF button to ON. The unit will be in Standby mode and the Standby indicator light (Fig 7. ) will be illuminated.


The 775 unit has two preset fan settings: a default or high fan setting and a reduced or low fan setting.

  • The high fan setting (Fig. 8) will be pre-selected by default.
  • The low fan setting may be pre-selected while in Standby mode.
    Change to Low Fan setting by
    pressing the appropriate button

    Fig. 8

Note: The high fan setting is recommended when placing the Bair Hugger blanket under the infant/child.

Note: Fan setting can be switched from high-low at any time by pressing button. However, these buttons will not place unit into Standby mode.

Normally if the blanket is placed on top of the infant/child, the low fan setting should be selected.

Select the desired temperature:
32oC (Low)   38oC (Med)   43oC (High)
and press appropriate button

E.g. (Fig 9.) High

This will turn the blower and heater ON.

If the infant/child is pyrexial - temperature can be set to Ambient mode

Note: It is recommended that caution should  be used if selecting a HIGH temperature in those infants or children with impaired circulation.

A LOW/MEDIUM (32°C/38°C) setting might be more suitable for those infants or children who are haemodynamically unstable in order to avoid sudden vasodilation and drop in blood pressure.

Note: In Ambient mode the heater is inactivated and the unit will supply room temperature air.

When the unit reaches the desired temperature, the "Temp in Range" light will illuminate. (Fig. 10 & 11)

Fig. 11

Note: The Temp in Range light will not illuminate if set in Ambient mode

Fig. 10

Once the Bair Hugger® 775 unit is on and running, a cotton blanket or sheet may be placed on top of the forced-air blanket. 

This will help minimize heat loss from the system and keep the forced-air blanket centered on the infant or child. 

Monitor the infant or child’s temperature continually if possible. If not then check temperature and skin frequently (every 20-30mins).

Ensure the forced-air blanket is not over the infant or child’s face/head.

The device can heat the infant or child quite rapidly, therefore frequent temperature and skin checks are necessary to ensure hyperthermia or thermal injury does not occur especially if air hose becomes loose from forced-air blanket connector.

In order to reduce the risk of suffocation. 

Although it is rare, it has also been reported that if the Bair Hugger® blanket is over the face or head and set at HIGH, there may be a risk of thermal softening of the endotracheal tube.

Adjust forced-air temperature or discontinue therapy as required depending upon infant or child’s temperature or clinical condition.

The device may heat the infant or child quickly, so vital sign instability may occur. 

If so inform senior nurse and medical staff and reduce air temperature or discontinue therapy. 

Warning lights:

If overheat warning light (Fig. 12) is illuminated and audible alarm sounds then discontinue therapy immediately.

 Fig. 12

Continuing to use the device when overheating may result in thermal injury.

Discontinuing therapy:

When temperature management therapy is complete, press the Standby button (Fig. 13).

 Fig. 13

Discard disposable components.

Disconnect the unit from power source,  wipe unit according to local infection control policy and store safely.


Forced air-warming systems have been in use for a number of years as a means of preventing and treating hypothermia and to provide warmth to cold or shivering patients. Forced-air warming systems such as the Bair Hugger® 775 are routinely used in the perioperative situation, emergency rooms or in critical care units, where hypothermia can complicate treatment and recovery by increasing oxygen demand due to shivering and affect patient coagulation.

The Bair Hugger® 775 may be used in the Paediatric Critical Care Unit for critically ill infants or children who have conditions that may result in an increased risk of hypothermia. 

Some studies suggest that forced-air warming, if used correctly, can increase the patient’s core temperature more quickly than other active warming methods, help reduce metabolic energy production and even decrease the requirement for specific cardiovascular drugs.

However, there are limitations in the use of forced-air warming systems such as the Bair Hugger® 775. 

The system should not be used over trans-dermal medications as the heat and subsequent vasodilatation of surface blood vessels may result in increased drug uptake. 

The warming system should never be used if the infant or child is on intra-aortic balloon pump therapy as thermal injury may occur if heat is applied to ischaemic limbs. 

Some studies have suggested that use of forced air warming devices may increase the risk of colonisation with potentially pathogenic organisms. However, other studies have found that there was no increase in bacterial counts. 


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  2. 3M Bair Hugger® Model 775 (2017) Temperature management unit – Information.
  3. 3M Bair Hugger®Model 775 (2017) Patient Warming with 3M™ Bair Hugger™ Temperature Management Unit 775. (YouTube user video guide)
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Editorial Information

Last reviewed: 01 July 2017

Next review: 01 July 2019

Author(s): Jeanette Grady, PICU Clinical Nurse Educator

Approved By: PICU Clinical Guideline group