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Pediatric Temperature Variation in the MRI Scanner Under General Anesthesia

This study has been completed.
Information provided by (Responsible Party):
Rutgers, The State University of New Jersey ( University of Medicine and Dentistry of New Jersey ) Identifier:
First received: May 6, 2010
Last updated: January 24, 2013
Last verified: January 2013

The number of children undergoing MRI imaging has increased significantly in the past years, because many young children cannot stay still for the duration of the scan, have difficulty tolerating the confined space and the noise produced by the Magnetic Resonance Imaging (MRI) machine, sedation or General Anesthesia is required in these cases. In the investigators institution, the investigators use General Anesthesia for children undergoing MRI.

Because children have a larger surface area to body weight ratio; hypothermia from passive heat loss is one of the anesthesiologists' concerns.

MRI requires a cool environment with low humidity; this specialized environment represents a significant thermal challenge to the anesthetized children. Since most temperature devices are not compatible with the MRI, the simple task to measure temperature change has never been investigated.

Children Requiring MRI

Study Type: Observational
Study Design: Observational Model: Case-Only
Time Perspective: Prospective
Official Title: Pediatric Temperature Variation in the MRI Scanner Under General Anesthesia

Resource links provided by NLM:

Further study details as provided by Rutgers, The State University of New Jersey:

Primary Outcome Measures:
  • To determine temperative change in children undergoing MRI under general anesthesia [ Time Frame: Start of MRI procedure until 30 minutes after its completion ]

Enrollment: 121
Study Start Date: March 2010
Study Completion Date: December 2011
Primary Completion Date: December 2011 (Final data collection date for primary outcome measure)
Children undergoing MRI

Detailed Description:

It is known that following the induction of anesthesia, core hypothermia occurs in three stages;

  1. Redistribution
  2. Linear phase
  3. Plateau phase Redistribution This accounts for the largest drop in core temperature of the three stages. Vasodilatation causes redistribution of heat from the core to the periphery.

Linear Phase This begins at the start of surgery as the patient is exposed to cold cleaning fluids and cool air flow in the theatre. Heat loss exceeds heat production, and most surgery does not extend past the linear phase.

  • Radiation contributes the most (40%) and is proportional to environment/core, temperature difference to the power of four.
  • Convection contributes up to 30% and is proportional to air velocity.
  • Conduction contributes up to 5% and is proportional to the difference in surface temperatures.
  • Evaporation contributes up to 15% and occurs from cleaning fluids, skin, respiratory and wound. A laparotomy can contribute up to 50% of the total.
  • Respiratory contributes 10% (8% evaporation of water; 2% heating of air) and is enhanced by the cooling effect of cold anesthetic gases.
  • Cold intravenous fluids. Plateau Phase Once core temperature falls below the thermoregulatory threshold, peripheral vasoconstriction increases and acts to limit the heat loss from the core department. When core heat production = heat loss to the peripheral compartment, core temperature reaches a plateau. Patients with an autonomic neuropathy (diabetics) have impaired sympathetic vasoconstriction and are unable to establish a core plateau in phase 3. Combined general and regional anesthesia will have a similar effect as the regional anesthetic (spinal/epidural) will prevent vasoconstriction in the legs; i.e. failure to establish a core plateau.

The ability to maintain body temperature is also compromised because anesthesia impairs intrinsic thermoregulatory response.

Heating devices including fluid warmers and bear huggers, commonly used in the Operating Room theaters, are incompatible with MRI.

On the other hand, MRI produces Radiofrequency Energy that transforms into heat within the patient's tissues. This may partially offset the heat loss.

The purpose of our study is to determine if children undergoing MRI under General Anesthesia become hypothermic and whether aggressive measures should be taken to prevent passive heat loss during MRI studies.

Study Design This is an observational, prospective non blinded study.


Ages Eligible for Study:   6 Months to 8 Years   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
Children 6 months to 8 years

Inclusion Criteria:

  • 6 months to 8 years undergoing general anesthesia-
  Contacts and Locations
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Please refer to this study by its identifier: NCT01119248

United States, New Jersey
University Hospital
Newark, New Jersey, United States, 07101
Sponsors and Collaborators
University of Medicine and Dentistry of New Jersey
Principal Investigator: Melissa Davidson, MD UMDNJ-NJMS
  More Information

Responsible Party: University of Medicine and Dentistry of New Jersey Identifier: NCT01119248     History of Changes
Other Study ID Numbers: 0120100053
Study First Received: May 6, 2010
Last Updated: January 24, 2013

Keywords provided by Rutgers, The State University of New Jersey:
Children MRI General Anesthesia

Additional relevant MeSH terms:
Central Nervous System Depressants
Physiological Effects of Drugs processed this record on May 24, 2017