|Ann. Medit. Burns Club - voL VI - n. I - March 1993
ACUTE AND CHRONIC PAIN RESULTING FROM BURN INJURIES
Anoesthesiology Department, General Hospital, Athens, Greece
SUMMARY. After a description of the physiology of burn pain, and the development of pain in the successive phases of the bum disease, suggestions are given for appropriate treatment, which may be local or systemic. Medical and nursing staff frequently underestimate pain and are unnecessarily worried about undesirable secondary effects, such as addiction, that it is feared may follow opioid administration. With individualized drug treatment, all bum patients can benefit from pain relief.
From the first moments of a burn injury, as well as throughout the entire period of treatment, pain affects the patient not only as a symptom but also as a difficult medical problem. Taking into account the average extended hospital stay and the necessity for the closest co-operation between the patient and the medical and nursing staff, especially during the various procedures, it is clear how essential it is to deal aggressively with the problem of pain in the burns patient (1,2).
Physiology of burn pain
For many decades the treatment of
pain, not only in burns patient but also more generally, was based on two major
Modern research has now shown that:
Pain as a result of burn injuries starts
starts immediately after the thermal, chemical or electrical injury to the tissues. This
is due to the production of high frequency impulses by the neural end plates which come
into contact with the surrounding air or have undergone partial destruction.
Elements of pain relative to the chronological phase of brun injury
Emergency phase. This phase starts immediately after the accident and lasts a few hours or days. The main treatment consists of the replacement of fluids and electrolytes and the maintenance of satisfactory circulatory, pulmonary and renal function. The pain during the initial phase is due to two reasons (I):
1. The direct trauma to the burn area and surrounding tissue, which in most cases begins immediately. Cases have however been reported in which the burn victim has proceeded immediately after the injury to carry out incredible feats of strength and endurance without feeling pain (i.e. to save others, to put out flames or to find assistance). This has been chronicled as Wall's Theory (1979), according to which the sense of pain is suppresed to allow other more vital biological mechanisms to operate. Also, in full skin-thickness burns the nerve endings are completely destroyed, so that the pain felt is either mild or moderate in nature and intensity, and refers more generally to the surrounding area. This pain is described as continuous and irritant during voluntary and involuntary movements.
2. Pain as a result of medical procedures (treatment and dressing of the burn area, venous catheterization, intubation, bronchoscopy, etc.). The pain produced is described as mild, moderate or intense, the degree depend depending on the personality of the patient, and the degree of emotional, psychological and physical stress present.
Acute phase. This stage follows and may last days or months. The management consists of local treatment and dressing of the burned areas and includes many procedures such as surgical intervention, physiotherapy, hydrotherapy and dressing changes. Pain during this stage is described as relatively low in intensity, interspersed however with brief periods of acute to unbearable pain during treatment procedures. This treatment-related pain has been described as "hell" by burn patients even when pre-treatment analgesics have been administered. It is interesting to note that after auto-transplant of skin the burned area ceases to cause pain while the donor site causes discomfort (1,4).
Recovery phase. This commences as soon as the burned surfaces have been covered or have healed. The primary target is functional rehabilitation and the minimalization of scar formation. This phase is related to the rebirth of tissue and causes local discomfort and paraesthesia. These symptoms, though relatively mild, have at times been described as being as unbearable as the initial burn pain (5).
Factors which influence burn pain
Medical factors (1,4,6)
Klein and Charlton, who studied the
effects of the duration of hospital confinement on the level of pain in adult burn
patients, found no correlation between length of stay and the amount of pain experienced.
Other researchers (Andreasen et al., 1972) report that many burn patients sense
ever-increasing levels of pain from the same procedures, with the passage of time. This
can be explained as a result of either lowering of the pain threshold or reduction of the
patient's resistance to pain.
A number of researchers have indicated
that in adult burn patients factors such as age, sex, nationality, education or
socioeconomic class do not appear to influence the level of pain felt and its
externalization in the behaviour of the patients (6,8).
It has been described that pain and
anxiety are two indissociable aspects of the same phenomenon, triggered by severe tissue
Treatment of burn-injury pain
1. The choice of method for local
treatment: the closed method is considered the most satisfactory despite the painful
The most widely accepted method of
treatment for severe pain is the administration of potent narcotic analgesics such as
morphine, pethidine, fentanyl or nalbuphine, together with the simultaneous administration
of tranquillizers or anxiolytic drugs (6,10).
1. Anxiolytics, tranquillizers: these
drugs should be delivered IV in small doses repeatedly. It should also be borne in mind
that hepatic metabolism in burn patients is delayed.
For the suppression of the very severe
pain that occurs during procedures or dressing changes, it is suggested that adequate
doses of opioid analgesics individualized to each patient's requirements be administered.
The action of these drugs may be reinforced by simultaneous administration of nitrous
oxide or ketamine.
RESUME. Après avoir décrit la physiologie de la douleur due aux brûlures et le développement de la douleur dans les phases successives, l'auteur présente des indications pour le traitement approprie, qui peut être local ou systémique. Uéquipe médicale et paramédicale fréquemment sous-estime la douleur et s'inquiète inutilement des effets secondaires indésirables, par exemple l'assuétude, que l'on craint puissent être causés par l'administration des opiacés. Avec un traitement pharmacologique individualisé, tous les patients brûlés peuvent tirer avantage du soulagement de la douleur.