Laboratory evaluation of various cold therapy modalities * WILLIAM C. MCMASTER,† M.D., SHARON LIDDLE, B.S., AND THEODORE R. WAUGH, M.D., Irvine, California From the Division of Orthopaedic
Surgery, University of California, Irvine, California
The local application of cold is an established treatment for the acute athletic injury and, in certain chronic situations, various methods are available to apply cold. This study was done in the adult canine thigh to evaluate the efficiency of various cooling devices to lower deep muscle temperature. Four modalities were tested: chipped ice, frozen gel, chemical ice envelope, and refrigerant-inflated bladders. A hypodermic temperature probe was inserted into the deep quadriceps muscle mass of the anesthetized animal and the thigh then cooled. Periodic temperatures were recorded for up to 60 min of cooling. The average reduction in temperature from control levels from four observations were recorded for each modality tested. Ice performed most efficiently, followed closely by frozen gel. Chemical ice and the refrigerant-injected bladder performed less satisfactorily. There were no ill effects to limb function or to skin integrity noted after the use of any of these devices over the observation period. This study did not discern the optimal temperature reduction needed to minimize the effects of trauma, but has established a relative efficiency by
*
Presented at the annual meeting of the American Orthopaedic Society for Sports Medicine, Tamarron, Durango, Colorado, July 1976.
t Address requests for reprints to: Division of Orthopaedic Surgery, University of California at Irvine, Irvine, California
92717.
which each modality
was
able to cool this labo-
ratory model, and suggested that ice or a frozen
gel
are
suitable alternatives.
Wth the evolution of knowledge specific
to
management of sports injuries, it has become genthat ice therapy in the acute situation has beneficial effects for the over-all management and recovery of the injured player. Acute ice application decreases local blood flow, thereby inhibiting excessive hemorrhage and edema. It additionally has a local analgesic effect of decreasing pain and dysfunction. In chronic injury situations the use of icing techniques includes contrast ice and heat treatments, as well as poststress icing to decrease swelling and pain. The methods available for applying cold are numerous and include ice chips in various containers, re-freezable units containing gelled solutions, chemical reaction devices, and inflatable splints using refrigerant gas to maintain compression, immobilization, and cold to the injured part. The availability of these various devices is not universal and economic factors as well as efficiency often dictates which are used. In an attempt to evaluate the potential of each to achieve and maintain temperature reductions in soft tissue, an experimental protocol was established using laboratory animals. Several factors were evaluated: (1) the ease of application of the technique; (2) the efficiency with which it cooled the deep soft tissues ; and (3) the potential for maintaining a lowered temperature over a suitable period of time
erally accepted
291
that would simulate the initial treatment the field&dquo; situation.
or
&dquo;on
MATERIALS AND METHODS
Adult mongrel dogs in the 60-lb range were used with thigh musculature sufficiently bulky to afford an insulated environment between skin and muscle tissues adjacent to the femur. The dogs were anesthetized with sodium pentabarbitol (30 mg/kg). The thighs were shaved of all overlying hair to elminate its insulation effect. Temperatures were recorded using a hypodermic thermistor probe, which was inserted beneath the skin in the deep quadriceps muscle mass immediately adjacent to the femoral shaft. The length of the probe was sufficient to place the recording tip under the main bulk of the cooling device. Prior to each cooling run, control temperature readings were recorded. The cooling device was then applied to the extremity and readings were taken at 15-min intervals for I hr. Two cooling sessions were utilized, separated by several days. Two intervals of cooling were monitored on each limb at each session. After each cooling run, I hr was allowed for the limb to regain heat and return the muscle mass to control level temperature before the next cooling run commenced. This occurred rapidly. Temperature measurements were recorded in de-
grees centigrade. The thermistor probes used were calibrated in a circulated water bath over the range of evaluation and checked against a laboratory thermometer. Correlation was quite linear (Fig. 1 ). The thermistor probe reproducability within 0.5 C of the thermometer reading was consistent throughout the range of temperatures encountered exper-
imentally. Four cooling modalities were evaluated: (1) Ice chips in a plastic bag of sufficient volume to cover the anterior half of the thigh musculature. (2) A snap-pack endothermic chemical reaction of sufficient size to adequately cover the anterior thigh musculature. (3) An inflatable plastic envelope that had to be wrapped about the thigh and then injected with gaseous refrigerant. Because of the configuration of the enveloping container a circumferential application of cold was necessary here. (4) A prefrozen flexible gel pack that contained sufficient volume to cover the anterior half of the thigh musculature. All devices were secured in place by circumferential wrapping with an expandable bandage. Except for the inflation device, a single application of each of the modalities was 292
~
~
--
-
~
-.
Fig. 1. The thermistor probe readings are plotted against recorded water bath temperatures using a laboratory thermometer. All recordings are in degrees centigrade. 77:c ~~/by~MMc~ both ~/’o6~ is ~M!~ linear. Pro~c Probe 7, 1, performance o/~ of &o
Surgery, University of California, Irvine, California
The local application of cold is an established treatment for the acute athletic injury and, in certain chronic situations, various methods are available to apply cold. This study was done in the adult canine thigh to evaluate the efficiency of various cooling devices to lower deep muscle temperature. Four modalities were tested: chipped ice, frozen gel, chemical ice envelope, and refrigerant-inflated bladders. A hypodermic temperature probe was inserted into the deep quadriceps muscle mass of the anesthetized animal and the thigh then cooled. Periodic temperatures were recorded for up to 60 min of cooling. The average reduction in temperature from control levels from four observations were recorded for each modality tested. Ice performed most efficiently, followed closely by frozen gel. Chemical ice and the refrigerant-injected bladder performed less satisfactorily. There were no ill effects to limb function or to skin integrity noted after the use of any of these devices over the observation period. This study did not discern the optimal temperature reduction needed to minimize the effects of trauma, but has established a relative efficiency by
*
Presented at the annual meeting of the American Orthopaedic Society for Sports Medicine, Tamarron, Durango, Colorado, July 1976.
t Address requests for reprints to: Division of Orthopaedic Surgery, University of California at Irvine, Irvine, California
92717.
which each modality
was
able to cool this labo-
ratory model, and suggested that ice or a frozen
gel
are
suitable alternatives.
Wth the evolution of knowledge specific
to
management of sports injuries, it has become genthat ice therapy in the acute situation has beneficial effects for the over-all management and recovery of the injured player. Acute ice application decreases local blood flow, thereby inhibiting excessive hemorrhage and edema. It additionally has a local analgesic effect of decreasing pain and dysfunction. In chronic injury situations the use of icing techniques includes contrast ice and heat treatments, as well as poststress icing to decrease swelling and pain. The methods available for applying cold are numerous and include ice chips in various containers, re-freezable units containing gelled solutions, chemical reaction devices, and inflatable splints using refrigerant gas to maintain compression, immobilization, and cold to the injured part. The availability of these various devices is not universal and economic factors as well as efficiency often dictates which are used. In an attempt to evaluate the potential of each to achieve and maintain temperature reductions in soft tissue, an experimental protocol was established using laboratory animals. Several factors were evaluated: (1) the ease of application of the technique; (2) the efficiency with which it cooled the deep soft tissues ; and (3) the potential for maintaining a lowered temperature over a suitable period of time
erally accepted
291
that would simulate the initial treatment the field&dquo; situation.
or
&dquo;on
MATERIALS AND METHODS
Adult mongrel dogs in the 60-lb range were used with thigh musculature sufficiently bulky to afford an insulated environment between skin and muscle tissues adjacent to the femur. The dogs were anesthetized with sodium pentabarbitol (30 mg/kg). The thighs were shaved of all overlying hair to elminate its insulation effect. Temperatures were recorded using a hypodermic thermistor probe, which was inserted beneath the skin in the deep quadriceps muscle mass immediately adjacent to the femoral shaft. The length of the probe was sufficient to place the recording tip under the main bulk of the cooling device. Prior to each cooling run, control temperature readings were recorded. The cooling device was then applied to the extremity and readings were taken at 15-min intervals for I hr. Two cooling sessions were utilized, separated by several days. Two intervals of cooling were monitored on each limb at each session. After each cooling run, I hr was allowed for the limb to regain heat and return the muscle mass to control level temperature before the next cooling run commenced. This occurred rapidly. Temperature measurements were recorded in de-
grees centigrade. The thermistor probes used were calibrated in a circulated water bath over the range of evaluation and checked against a laboratory thermometer. Correlation was quite linear (Fig. 1 ). The thermistor probe reproducability within 0.5 C of the thermometer reading was consistent throughout the range of temperatures encountered exper-
imentally. Four cooling modalities were evaluated: (1) Ice chips in a plastic bag of sufficient volume to cover the anterior half of the thigh musculature. (2) A snap-pack endothermic chemical reaction of sufficient size to adequately cover the anterior thigh musculature. (3) An inflatable plastic envelope that had to be wrapped about the thigh and then injected with gaseous refrigerant. Because of the configuration of the enveloping container a circumferential application of cold was necessary here. (4) A prefrozen flexible gel pack that contained sufficient volume to cover the anterior half of the thigh musculature. All devices were secured in place by circumferential wrapping with an expandable bandage. Except for the inflation device, a single application of each of the modalities was 292
~
~
--
-
~
-.
Fig. 1. The thermistor probe readings are plotted against recorded water bath temperatures using a laboratory thermometer. All recordings are in degrees centigrade. 77:c ~~/by~MMc~ both ~/’o6~ is ~M!~ linear. Pro~c Probe 7, 1, performance o/~ of &o
