Page 380 Guide to Pain Management in Low-Resource Settings

368 Andreas Kopf

Pain while dysesthesia be used preferentially for an abnormal
Th e International Association for the Study of Pain sensation that is considered to be unpleasant. Dysesthe-
(IASP) defi nes pain as “an unpleasant sensory and emo- sia does not include all abnormal sensations, but only
tional experience associated with actual or potential tis- those which are unpleasant.
sue damage, or described in terms of such damage.” Th is Patient-controlled analgesia (PCA)
broad defi nition acknowledges that pain is more than a
Pain medication given through an intravenous or epi-
sensation subsequent to the electrical activation of no-
dural catheter may be either applied continuously or by
ciceptors (nociception). It includes cognitive, emotional,
the nurse or doctor or self-administered by the patient.
and behavioral responses, which are also infl uenced by
With PCA, patients control the frequency of medication
psychological and social factors. Pain is always subjec-
dosing, depending on how much they need to control
tive. Each individual learns the application of the word
the pain. PCA is usually used for patients recovering
through experiences related to injury in early life. Biolo-
from intra-abdominal, major orthopedic, or thoracic
gists recognize that those stimuli which cause pain are
surgery, and for chronic pain states, such as those due
liable to damage tissue. Accordingly, pain is that expe-
to cancer requiring parenteral administration of opioids.
rience we associate with actual or potential tissue dam-
Usually PCA uses electronic pumps that allow docu-
age. It is unquestionably a sensation in a part or parts of
mentation of the patient’s analgesic demand and safety
the body, but it is also always unpleasant and therefore
by locking the pump function for some time (usually 10
also an emotional experience. Experiences that resem-
minutes) after each demand dose self-administered by
ble pain but are not unpleasant, e.g., pricking, should
the patient.
not be called pain. Unpleasant abnormal experiences
(dysesthesias) may also be pain but are not necessarily Peripheral neuropathic pain
so because, subjectively, they may not have the usual Pain initiated or caused by a primary lesion or dysfunc-
sensory qualities of pain. tion in the peripheral nervous system, such as diabetic
Many people report pain in the absence of tis- polyneuropathy.
sue damage or any likely pathophysiological cause; usu-
Phantom pain
ally this happens for psychological reasons. Th ere is
usually no way to distinguish this experience from that Pain that develops after an amputation in the area of
due to tissue damage if we accept the subjective report. the missing limb. Th e diagnosis of phantom pain has
If people regard their experience as pain and if they re- to exclude fi rst the presence of stump pain (e.g., due
port it in the same ways as pain caused by tissue dam- to insuffi cient surgical coverage of the stump tissues)
age, it should be accepted as pain. Th is defi nition avoids and phantom sensations (nonpainful, but nevertheless
tying pain to the stimulus. Activity induced in the noci- frightening “feelings” in the lost limb). Since phantom
ceptor and nociceptive pathways by a noxious stimulus pain is mostly generated in the central nervous system,
is not pain, which is always a psychological state, even mostly in the corresponding sensory-motor region of
though we may well appreciate that pain most often has the cortex, therapy is usually not directed peripher-
a proximate physical cause. ally but centrally. Patients and their relatives sometimes
feel that—since pain in a missing body part should not
Pain threshold be possible—something is wrong with them. Th ere-

Th e least experience of pain that a subject can recognize. fore, simply educating the patient and family about the
causes of the pain may bring considerable relief.
Pain tolerance level
Physician-assisted suicide
Th e greatest level of pain that a subject is prepared to
tolerate. As with pain threshold, the pain tolerance level Actions by a doctor that help a patient commit suicide.
is the subjective experience of the individual. Th ough the doctor may provide medication, a prescrip-
tion, or take other steps, the patient takes his or her
Paresthesia own life (for instance, by swallowing the pills that are
An abnormal sensation, whether spontaneous or expected to bring about death). While physician-assist-
evoked. It has been agreed that paresthesia be used to ed suicide is legal in Th e Netherlands, Belgium, Luxem-
describe an abnormal sensation that is not unpleasant burg, and Switzerland, it is illegal in all other countries