While I agree that swelling and heat, if present, are reliable and relatively objective signs, I would like to add one caveat to the lecturer's section on the clinical evidence of inflammation with regard to the determination of tissue healing phases and appropriate treatment.
Having previously worked with students as a clinician in a chiropractic college clinic, and now working in a hospital environment with medical physicians and family practice residents, I find that many physicians (both chiropractic and medical), as well as most patients, are confused as to when ice or heat should be used for an injury. The general advice of applying ice for the first 24 to 48 hours followed by heat is based upon the idea that the patient has progressed from the acute inflammatory phase to the repair or regeneration phase on a normal time scale.
I am sure that anyone who has practiced chiropractic for more than a few days knows that many patients will present with signs of acute inflammation as long as a week after the initial injury. Overuse of the injured area, premature application of heat, and other factors can prolong the normally short-lived inflammatory phase. Research also shows that the overuse of ice can slow the healing process, so how does one assess when it is appropriate to use ice and heat? Many colleagues I have spoken simply guess based on time from the onset of symptoms, without much clinical rationale on which to base their decision, but there is a better (though not perfect) rule-of-thumb you can follow, and teach your patients to make this determination more accurate.
Of course, the best objective evidence of the acute inflammatory phase is the heat and swelling found during palpation, but the depths of the structures involved, and often the thickness of the patient's superficial tissues, can sometimes mask these signs.
It is true that almost every patient presenting to our offices has pain as a chief complaint, so the mere fact that a patient hurts cannot guide our clinical rationale. However, as the physiology changes during the different phases of inflammation and healing, the factors stimulating the pain also change. This means that the quality of the patient's pain may be one of the most invaluable signs in determining the transition of the acute phase into the early repair or regeneration phase.
Pain during the acute inflammatory process is caused by multiple factors. Besides pain generated by the initial damage to the injured tissue, pressure from tissue swelling and stretching of sensitive structures has been found to be a significant contributor to the pain, as are the multitude of acute inflammatory chemicals released by local tissue destruction and the invading cellular response. Chemicals such as prostaglandins, leukotrenes, bradykinin, histamine, etc., and the change in pH all contribute to cause constant chemically stimulated depolarization of the pain fibers. The concentration of these chemicals, and their resultant sequelae of swelling and the constant barrage of the pain neurons, are slowly removed as the acute inflammatory phase shifts to the repair-regeneration phase. Hence, their influence on the constant perpetuation of "c-fiber" stimulation diminishes.
While the pain neurons continue to have a lowered threshold of firing, they no longer have constant chemical irritation. The quality of pain at this phase is one in which the patient can find a pain-free or relatively pain-free position (depending on severity of initial tissue damage) but has pain with movement, or only when weight-bearing (subject to mechanical stress). During this phase, patients may say that they don't feel pain, just "stiffness," unless they make a provocative movement (which can include weight-bearing).
As a general rule, which is very easy for patients to understand, inflammation is present if there is no pain-free position (chemically mediated pain), and if the condition is in the repair phase when the patient can get into a pain-free position, but still has pain with movement or other mechanical stress to the tissues. In conjunction with the use of ice or heat, here are two "rules of thumb":
- no pain-free position - use ice
- pain-free position, but pain with movement - may use heat
The advantage of this general rule-of-thumb when determining the use of heat or ice may be obvious. During the transition from inflammatory to repair phase, the patient may find more "stiffness" in the morning and be able to find a pain-free position. However, due to the early nature of the healing, activities during the day may elicit a recurrence of inflammatory response, and hence a return of constant pain by the evening. At this time, it would be prudent to use ice again as opposed to heat, which may have been more appropriate earlier in the morning during the stiffness. Also, if the patient has been progressing nicely and has an acute "flare-up," it allows the patient to know when to use ice again instead of heat.
Since premature application of heat can prolong the inflammatory response, but prolonged application of ice may prolong tissue healing, using the applied knowledge of physiology of inflammatory pain propagation to determine the best approach is easier for the patient, easier for other health care providers who do not have our palpatory skills, and easier for those chiropractors who may not be sure of their palpatory findings. However, it is only one sign to be considered in conjunction with other examination findings in determining a comprehensive clinical course of treatment.
The above rule-of-thumb only applies to acute pain. The unique physiology perpetuating chronic inflammation may actually respond better to heat than ice, although this is a point of controversy in the literature. Of course, always keep in mind that a person with chronic inflammation can develop an acute inflammatory reaction in the same area.
I hope you find this information useful.
Duane T. Lowe,DC,DABCI
Scott AFB, Illinois