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From The Science of Caring magazine
No Pain Our Gain
Pain is one sensation all humans understand and share. But is pain relief
equally universal? Not by a long shot, say researchers Christine Miaskowski,
chair of the department of physiological nursing in the UCSF School
of Nursing and Jon Levine, a pioneering pain specialist in the School
of Dentistry. Their collaboration, which began when Miaskowski was a
Robert Wood Johnson postdoctoral fellow in Levine's laboratory seven
years ago, has revealed a surprising gender difference in pain relief
that has intriguing implications for pain management.
The studies, which focused on a class of drugs known as kappa opioids
(so named because of the kappa receptor molecules they attach to on
the surface of some cells), compared the pain responses of men and women
who had their wisdom teeth removed. In the first study, Miaskowski and
Levine combined a kappa opioid with a sedative to learn if the combination
improved pain relief. It did -- but only for women. A second study with
two different kappa drugs confirmed the results. Women had more and
longer relief than men.
"Kappa opioids are not regarded as the best pain medicine in the
world," says Miaskowski. Patients who must use one of the mu-receptor
opioids chronically, morphine for example, cannot switch to kappa drugs
because of their side effects, which include withdrawal symptoms. Moreover,
when compared to the reported pain relieving effects of the mu-opioids
(codeine being another common example), kappa opioids were less effective.
What these clinical trials failed to examine, however, were the potential
gender differences, in large part because the trials were conducted
mostly on men.
"There were clues in the footnotes," Miaskowski explains,
"but no one paid much attention to the fact that men and women
reported different success with morphine, for example." Levine
concurs. "Kappa opioids have been around a long time, but it never
clicked that they were not doing anything for men. If anything, their
complaints were treated as a personal failing because clinicians had
blinders on."
Now that the difference has been revealed, Levine and Miaskowski, who
maintains her own physiology lab in the School of Nursing, have continued
their collaboration into its reasons. Levine has studied and ruled out
hormonal differences, leading him to search for a more mechanistic basis.
Miaskowski meanwhile is evaluating the role of the placebo response
and concentrating on methods for maximizing the painkilling effects
of kappa drugs. She also is keeping a close watch on any subsequent
increase in side effects. "One of the advantages nurses and other
clinicians bring to research is thinking about all of the potential
consequences."
Scrutinizing Potential Consequences
As to the impact of their work on clinical practice, Miaskowski and
Levine are uncertain but hopeful. "Medicine is inherently conservative,"
Levine says, "and that is, on balance, appropriate. I think it
will take time for the idea of gender differences to pain to influence
what is happening on the wards." Miaskowski thinks that their research
will at least speed acceptance of the notion, particularly since pain
is such a problem with the cancer patients she is working to help. "I
do believe that academic clinicians are becoming more aware and are
beginning to look at this problem more critically."
Other studies may one day confirm, as is popularly believed, that women
truly cope with pain better than men. But as this UCSF research indicates,
until the medicines prescribed to women and men have equal pain-relieving
effects, it may be that women's perceived ability to cope with pain
will stem from the unhappy fact that they are feeling more of it.
Developing A "Language" for Gauging Pain
 Just
as there are differing perceptions of pain, there also are different
degrees. And for Kathleen Puntillo, director of the School of Nursing's
Critical Care/Trauma and Acute Care Nurse Practitioner programs, there
also is the problem of communication. "In both the emergency department
and intensive care units, nurses and doctors need to be able to assess
the degree of pain a patient is feeling in order to manage it. But there
are barriers."
In emergency rooms, these barriers include time, language, a sense of
urgency and as Puntillo found, the absence of an easy system for gauging
and reporting pain. To learn if such a system was possible, Puntillo
and her emergency physician colleague, Martha Neighbor, zeroed in on
the language issue and tested the validity of a simple pain-rating scale
in English-speaking and Spanish-speaking emergency room patients. "It
seems simplistic to ask patients to rate their pain on a scale of 0
to 10, but we showed that it worked well for both categories of participants."
Having such a system in place would allow clinicians a quick way to
assess the effectiveness of treatments. The problem, Puntillo admits,
is that if questions about pain are even asked in emergency room visits,
responses are not usually documented, making comparative measures over
time impossible. And when it comes to pain management, emergency room
personnel consider many other factors, such as the possibilities of
patient drug abuse or their need not to mask abdominal pain in order
to make a diagnosis. (The merit of these and other factors that may
impede pain management is controversial.)
Nurses and doctors working with intensive care patients face a different
set of pain-management problems. "We used to think that pain assessment
was impossible when the patient couldn't verbalize," says Puntillo.
But her research and that of others has shown that there are some behavioral
cues -- grimacing, frowning, restlessness -- that clearly indicate degrees
of discomfort. Translating these observations into adequate painkilling
drug dosages is the challenge, and one that Puntillo believes can be
helped with education and standardized bedside tools. With that in mind,
and with the help of nurses on a critical care pain task force, she
developed a laminated ready-reference form that now can be found alongside
every bed in the adult critical care units at Moffitt-Long Hospitals.
The form includes the outline of a human body. Patients who are awake
but cannot speak can point to the parts of their bodies that hurt.
Aggressive Pain Control
The use of pain assessment tools and pain management practices has not
been uniform, setting the stage for a new NIH-funded study that will
allow Puntillo and her team to examine how nurses and physicians make
pain-management decisions in emergency departments. This will include
how decisions are influenced by the manner in which patients present.
The goal, as the 1992 Agency for Health Care Policy and Research guidelines
suggest, is aggressive pain control. Based on surveys and policies that
revealed that patients with acute pain were suffering unnecessarily,
the guidelines also underscored the consequences of such untreated pain.
Explains Puntillo, "Work in the basic sciences has shown that if
we don't treat acute pain, there may be changes in the central nervous
system that promote the development of chronic pain. My feeling is that
we have the tools and effective pain relievers for acute pain, so why
not use them?"
Source: Jeff Miller
From The Science of Caring
Magazine of the UCSF
School of Nursing, Spring 1999
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