Cases & Commentaries

Too Hot For Comfort

Commentary By Heather Cleland, MBBS; Jason Wasiak, BN, MPH

The Case

A 4-month-old infant admitted to rule out sepsis
was receiving maintenance intravenous (IV) fluid and IV antibiotics
via a peripheral line in the left antecubital region. During shift
report, nurses noted that the extremity was taut and the infant was
irritable. The nurses further assessed the site and removed the IV.
Prior to ending her shift, the nurse placed a warm compress on the
infiltrate site and notified the resident physician.

Within the next hour, the nurse coming on shift
assessed the infant further and discovered redness and a burn at
the site as a result of the warm compress. The compress was
removed, and the physician called a surgical consultant for further
evaluation. The infant was treated with topical ointment; no
surgical intervention was necessary.

The Commentary

This case scenario describes an incident in which
a case of extravasation injury was treated with topical heat via
the application of a warm compress. According to the account given,
the application of the compress resulted in a cutaneous burn, which
healed with conservative therapy.

Before we address the appropriate use of thermal
therapies and the harm they can cause, it is important to entertain
the possibility that the "burn" in this case may have been the
result of extravasation of an irritating solution, rather than a
result of thermal injury. To make this distinction, one should
first determine whether the solution is an irritant. Commonly used
agents that cause severe extravasation injuries include
antineoplastic, inotropic, or osmotically active agents and certain
antibiotics. Next, it is important to examine the extremity. In
this case, the tautness of the extremity implied that a significant
amount of fluid had been delivered to the subcutaneous and possibly
muscular compartments of the arm, making it more likely that this
was an extravasation injury.

Whatever the cause of this initial injury, the
use of thermal therapies by nursing or allied health professions as
a treatment option remains common in clinical practice. Although
the evidence supporting this therapy is relatively scant, the
widespread use of warm packs in a variety of clinical situations
suggests that providers feel the therapy can be
beneficial.(1)
Below, we review a number of indications for thermal therapy, then
discuss the potential harm that can result from inappropriate use
of heat.

Use in Extravasation Injury and
Thrombophlebitis

Hastings-Tolsma and colleagues (2) reported on the experimental effects of warm vs. cold
packs in adult volunteers with intentional extravasation of fluid
into the subcutaneous tissues and found improved mobilization of
fluid with the warm packs. Whitney and colleagues (3) reported that local warming increases tissue perfusion
and oxygen supply by overcoming local vasoconstriction and
increasing blood flow to tissues. These observations provide some
pathophysiologic rationale for thermal therapy, but there is
limited evidence in the form of randomized controlled trials (RCTs)
to support the use of topical thermal therapy in fluid
extravasation or other clinical situations. Moreover, we found no
systematic reviews or RCTs that supported the clinical
effectiveness of thermal treatment of thrombophlebitis or acute
inflammation resulting from IV therapy. Indeed, the literature on
burns supports the use of cooling therapy to minimize tissue
damage. The efficacy of cooling may be due to limitation of the
postburn inflammatory reaction and minimization of inflammatory
burn-associated edema.(4) In
light of this evidence base, our practice is to cool the wound, and
not apply heat, in patients with extravasation injury and
thrombophlebitis.

Use to Promote Wound
Healing

In contrast, the wound healing literature
generally supports the use of warming therapies.
Pathophysiologically, the warming of injured tissue using various
devices appears to promote several actions relevant to healing. For
example, studies suggest that local warming creates an environment
that is conducive to biochemical and enzymatic reactions, which in
turn improves local circulation and oxygen tension. Experts have
postulated that local warming increases the availability of immune
cells and alters inhibitory factors in the local wound environment
to promote healing.(5,6)
One study found significant and beneficial changes to the wound
microenvironment, including improved fibroblast activity with
warming (7),
and a number of animal studies have shown that warming decreases
bacterial counts.(8) The
clinical correlation of these scientific observations is a bit
uncertain. Although a systematic review (3) found that infection rates were lower and oxygen
tension higher in acute and chronic wounds treated with warming
therapies, this study had a number of methodological
shortcomings.

Use in Patients with
Pain

A Cochrane review of the use of warming therapy
in rheumatoid arthritis (RA) found no objective improvements but
also found no adverse reactions and that patients preferred
thermotherapy over no therapy.(9)
This preference demonstrates that thermal therapy does help relieve
pain in both RA and various painful musculoskeletal conditions. For
example, another trial assessing the efficacy of local heat
application in relieving pain found that acute low back pain was
relieved by active warming.(10)

The Safety of Thermal
Therapy

In summary, thermal therapy probably relieves
pain in certain musculoskeletal conditions, and there is
pathophysiologic rationale, at least, to believe that it may help
some patients with wound healing. While the Cochrane review
(9)
concluded that thermal therapy causes no adverse events, this case
clearly demonstrates that this treatment does carry risks.

In this case, a contact burn was noted at the IV
site as a result of the application of the warm compress for a
prolonged period of time. Burn injury (including scalds) caused by
medical therapies usually results from prolonged exposure and/or
poor thermoregulatory control of the device; the risk is
particularly high in vulnerable populations-especially children,
the elderly, and those with insensate skin, chronic medical
conditions (such as diabetes mellitus and peripheral vascular
disease), and altered mental status.(11)

Even in those without risk factors for burn
injury, temperatures greater than 140°F will cause thermal burn
within 4 seconds.(12) A
typical hot water tap produces water at a temperature of about
120°F, while a hot cup of coffee may have a temperature of up
to 180°F. In other words, thermal therapy has a relatively
narrow therapeutic window-the difference between a "therapeutic
temperature" (keeping in mind the limited evidence of efficacy in
any clinical condition) and a potentially toxic one is relatively
small. Of note, wet heat (scald) travels much more rapidly into
tissue, and is thus much more dangerous, than dry heat (flame). A
surface temperature of more than 156°F by wet heat produces
immediate tissue death as well as vessel clotting, while a
significantly higher temperature would be required with dry
heat.

If heating devices are to be used, then the
temperature of the device should be accurately measured and kept
below 140°F. This effectively precludes the use of hot water
bottles (unless the water temperature can be accurately measured)
and of packs heated in microwave ovens but whose temperature may be
unknown.

Other strategies to increase the safety of heat
application include:

  • Placing the heating device on top of,
    not underneath, the patient, if possible.
  • Assessing skin integrity frequently and
    adjusting the therapy interval according to the patient's skin
    tolerance.
  • Restricting use of the heating device to
    no longer than 15 to 20 minutes.

It should be noted that areas with decreased
blood flow are also more prone to tissue damage, due to decreased
ability to conduct heat away from the area. A common example of
this is when Plaster of Paris (which becomes quite hot as it
"sets") is applied to limbs that are ischemic due to tourniquet
application intraoperatively.

Patient education and instruction regarding use
of a heating device are important parts of any therapy. Nursing and
allied health staff should not apply an unregulated heating device
directly onto a patient's skin unless a protective cover that
cocoons the device and prevents its having direct contact with the
skin is provided. Vigilant monitoring of the patient's skin for
marked redness, swelling, pain, and edema should also be
instituted; if seen, the heating device should be removed
immediately.

This clinical scenario was fortunately associated
with no significant burn injury. However, every burn surgeon has
seen iatrogenic burn injury as the result of
“therapeutic” application of local warming devices. It
is time that the use of unregulated local heat therapy disappeared
from the therapeutic armamentarium. Further investigation into the
therapeutic efficacy of this modality, and the best practices for
applying heat safely in a variety of conditions, is
warranted.

Take-Home Points

  • Although heat therapy is common, little
    evidence supports its effectiveness.
  • Thermal therapy may relieve pain for
    certain musculoskeletal conditions and may help in wound
    healing.
  • If heat therapy is used, the device must
    be kept at a temperature below 140°F and must be used for no
    longer than 15 to 20 minutes.
  • The patient's skin should be vigilantly
    monitored and heat removed immediately if there is evidence of
    injury, such as severe redness, swelling, pain, or edema.

Heather Cleland, MBBS
Director, Victorian Adult Burns Service
The Alfred Hospital
Melbourne, Australia

Jason Wasiak, BN, MPH
Senior Research Fellow, Victorian Adult Burns Service
The Alfred Hospital
Melbourne, Australia

References

1. Chandler A, Preece J, Lister S. Using heat
therapy for pain management. Nurs Stand. 2002;17:40-42. [go to PubMed]

2. Hastings-Tolsma MT, Yucha CB, Tompkins J,
Robson L, Szeverenyi N. Effect of warm and cold applications on the
resolution of i.v. infiltrations. Res Nurs Health. 1993;16:171-178.
[go to PubMed]

3. Whitney JD, Wickline MM. Treating chronic and
acute wounds with warming: review of the science and practice
implications. J Wound Ostomy Continence Nurs. 2003;30:199-209.
[go to PubMed]

4. Venter TH, Karpelowsky JS, Rode H. Cooling of
the burn wound: the ideal temperature of the coolant. Burns.
2007;33:917-922. [go to PubMed]

5. Rabkin JM, Hunt TK. Local heat increases blood
flow and oxygen tension in wounds. Arch Surg. 1987;122:221-225.
[go to PubMed]

6. Ikeda T, Tayefah F, Sessler DI, et al. Local
radiant heating increases subcutaneous oxygen tension. Am J Surg.
1998;175:33-37. [go to PubMed]

7. Xia Z, Sato A, Hughes MA, Cherry GW.
Stimulation of fibroblast growth in vitro by intermittent radiant
warming. Wound Repair Regen. 2000;8:138-144. [go to PubMed]

8. Lee ES, Caldwell MP, Talarico PJ, Kuskowski
MA, Santilli SM. Use of a noncontact radiant heat bandage and
Staphylococcus aureus dermal infections in an ovine model. Wound
Repair Regen. 2000;8:562-566. [go to PubMed]

9. Robinson V, Brosseau L, Casimiro L, et al.
Thermotherapy for treating rheumatoid arthritis. Cochrane Database
of Syst Rev. 2002:CD002826. [go to PubMed]

10. Nuhr M, Hoerauf K, Bertalanffy A, et al.
Active warming during emergency transport relieves acute low back
pain. Spine. 2004;29:1499-1503. [go to PubMed]

11. Barillo DJ, Coffey EC, Shirani KZ, Goodwin
CW. Burns caused by medical therapy. J Burn Care Rehabil.
2000;21:269-273. [go to PubMed]

12. Herndon D, ed. Total Burn Care. 2nd ed.
London, England: WB Saunders; 2002.