Download Around-the-Clock (ATC) Dosing of Analgesics

PAIN CARE
Around-the-Clock (ATC) Dosing of Analgesics
Chris Pasero, MS, RN-BC, FAAN
TWO BASIC PRINCIPLES of providing effective pain
management are preventing pain and maintaining a pain
rating that allows the patient to accomplish functional
or quality-of-life goals with relative ease. These may
require that the mainstay analgesic be administered on
a scheduled around-the-clock (ATC) basis, rather than
‘‘as needed’’ (PRN) to maintain stable analgesic blood
levels. ATC dosing regimens are designed to control baseline pain, defined as the pain the patient reports as being
the average pain intensity experienced for 12 hours or
more during a 24-hour period.1 In other words, ATC dosing should be used when pain itself is ATC (continuous)
or present for 12 or more hours each day. Many types of
persistent (chronic) cancer and noncancer pain are continuous, and most postoperative pain is continuous for
at least the first 24 hours after surgery.
The use of continuous analgesia prevents the undertreatment of pain in patients who are hesitant to request pain
medication and eliminates delays that patients encounter
waiting for caregivers to prepare and administer pain
medication. Another benefit is that patients have been
shown to be more adherent to their analgesic regimen
when analgesics are prescribed ATC. A five-week study
of outpatient oncology patients with pain who kept a daily
diary to record level of pain and analgesic intake showed
that overall adherence rates for those who took their analgesics ATC ranged from 84.5% to 90.8% compared
with 22.2% to 26.6% in those who took them PRN.2 The
researchers pointed out that one might speculate that
the reason for lower adherence rates for the PRN regimen
was because those patients were experiencing less pain
and therefore needed fewer analgesics; however, there
were no significant differences in the percentage of
patients who reported severe pain (numerical pain rating
$7) in the ATC compared with the PRN group.
Chris Pasero MS, RN-BC, FAAN, is a pain management educator and
clinical consultant in El Dorado Hills, CA.
Address correspondence to Chris Pasero, 1252 Clearview Drive, El
Dorado Hills, CA 95762; e-mail address: [email protected].
Ó 2010 by American Society of PeriAnesthesia Nurses
1089-9472/10/2501-0009$36.00/0
doi:10.1016/j.jopan.2009.12.003
36
ATC dosing for continuous pain may be accompanied by
provision of additional analgesic doses (called breakthrough doses, supplemental doses, or rescue doses) as
needed to relieve pain that exceeds, or breaks through,
the ongoing pain. For example, when analgesia for persistent cancer pain is provided orally, ATC dosing often is accomplished with a combination of modified-release
opioid given at scheduled times, with breakthrough doses
of short-acting opioid given if pain breaks through. When
invasive routes are used to manage pain, such as refractory cancer pain or after surgery, a continuous infusion
with PCA boluses or clinician-administered supplemental
doses accomplishes the same objectives as this oral approach. Caution is recommended when using continuous
infusions (basal rates) with PCA in opioid-naı̈ve individuals; rather than routinely initiating therapy, basal rates
are often added postoperatively if the patient is unable
to sleep or rest adequately because of pain.3
Research on ATC Dosing
There is surprisingly little research on the use of ATC analgesic dosing. An early crossover study showed that
scheduled ATC dosing of analgesics improved pain relief
and mood level compared with on-demand PRN dosing
in patients with persistent noncancer pain.4 A more recent study of medical inpatients with pain from a variety
of origins compared ATC scheduled opioid doses with
PRN opioid doses and found that those who received
ATC doses had lower pain intensity ratings.5 As might
be expected, a significantly greater percentage of the prescribed opioid was administered when it was given ATC
(70.8%) compared with PRN (38%); however, there
were no differences in adverse effects between the two
groups. An observational, prospective study administered
ATC oral short-acting morphine to patients after orthopedic surgery, and reported average pain scores were 2.4 at
rest and 4.0 during movement in bed.6 Nausea and vomiting, the most common adverse effects, were reported by
22%, and no one required naloxone.
Other research has shown conflicting results. A study of
outpatients with pain from bone metastases found no
significant differences in average, least, or worst-pain
intensity in patients taking ATC or PRN opioids, but
Journal of PeriAnesthesia Nursing, Vol 25, No 1 (February), 2010: pp 36-39
PAIN CARE
significantly higher opioid prescriptions and intake (12.4
times more) were reported in patients who took ATC opioids.7 The researchers noted that their findings challenge
the accepted principle of treating continuous pain with
ATC analgesics but offered a number of possible explanations. These included that the opioid analgesic regimens
may not have been effective for the type of pain the patients had (bone pain), analgesic doses were not titrated
to optimal effect, and the possibility that comparisons
were difficult because the two groups were not receiving
the same analgesics (PRN received short-acting opioids
and ATC received long-acting opioids). Another study randomized children to receive ATC or PRN acetaminophen
plus codeine after tonsillectomy and found no differences
in pain intensity ratings or pain relief scores.8 Both groups
experienced moderate to severe pain, and similar to the
previous study, more analgesic (two times more) was consumed by those in the ATC group. There were no differences in adverse effects, such as nausea and vomiting,
sedation, and dizziness, which were described as moderate to severe.
These studies suggest the need for more research evaluating the best method for analgesic dose administration in
a variety of populations and for a variety of types of
pain. It is important that future research includes the
effect of dosing regimens on functional outcomes as
well as pain relief. Until research proves otherwise, prevention of the recurrence of pain with scheduled ATC
dosing is recommended for continuous types of pain.
Awakening Patients for Analgesic
Administration
Nurses often wonder whether patients taking ATC shortacting opioids should be awakened and given pain medication and whether they should teach patients in the
home setting to wake themselves during their normal
sleep time to take their pain medications to keep pain under control. There is very little research guiding this practice, and none could be found in opioid-naı̈ve patients
with acute pain. The consensus expert opinion of the
European Association for Palliative Care (EAPC) regarding
palliative care patients with moderate to severe pain who
are taking short-acting (not modified-release) opioids is to
give a double dose of the short-acting opioid at bedtime,
rather than a single dose, and awaken the patient for a second dose four hours later.9 This is based on the assumption that doubling the dose will prolong the duration of
analgesia long enough to prevent awakening with pain.
Some research on the efficacy of double dosing versus
usual dosing has been done in patients with cancer
pain. A double-blind, randomized, crossover study that
compared the two methods found that average pain,
strongest night pain, and sleep quality were slightly better
in patients who took a double dose compared with those
37
who took a single dose, but the difference was not clinically significant.10 The researchers suggested that the
slight difference may have been because of initial higher
exposure to morphine’s metabolite M6G, which is a potent analgesic. An earlier prospective study of palliative
care patients found all of the pain scores were worse in
patients who took a double dose of opioid compared
with those who took a single dose at bedtime followed
by another dose four hours later.11 Further, those in the
double-dose group required more breakthrough analgesia
and experienced more adverse effects.
Double doses of opioids should not be given to opioidnaı̈ve patients, but outpatients who are opioid-tolerant
and have persistent pain can be told to try double dosing
and usual dosing, as described before, to see which works
best to keep their pain under control. Alternatively, patients taking short-acting opioids can be switched to
a modified-release formulation in an effort to improve
sleep at night.
Both opioid-naı̈ve and opioid-tolerant patients with continuous pain in the hospital setting after surgery should
be awakened to take their pain medication. Awakening
postoperative patients with moderate-to-severe pain to
take their pain medication is especially important during
the first 24 to 48 hours of therapy to keep pain under control. Patients should be told that this helps to avoid waking with severe pain and that if their pain is well
controlled, they are more likely to go back to sleep
quickly. A sedation and respiratory status assessment
should be conducted before administration.12 The patient
can transition gradually to PRN dosing and sleeping during the night as pain resolves.
Breakthrough Pain
Breakthrough pain (sometimes called ‘‘pain flare,’’ ‘‘episodic pain,’’ or ‘‘transient pain’’) is defined as a transitory
exacerbation of pain in a patient who has relatively stable
and adequately controlled baseline pain.13 The intensity
of pain is sometimes included in the definition of breakthrough pain, ie, a transient increase in pain to greater
than moderate intensity occurring on a baseline pain of
moderate intensity or less.1
Like its definition, there is variation in the description of
breakthrough pain. Some describe it as occurring spontaneously (not related to activity), rapidly increasing to
a high intensity level, and having a short duration (3045 minutes).14 Others describe subtypes of breakthrough
pain, noting that it can have a sudden or gradual onset and
can be brief or prolonged; some episodes are spontaneous and others are associated with an identifiable precipitant.15 When breakthrough pain is brief and precipitated
by a voluntary action, such as movement, it is referred to
as incident pain.16 Another subtype, idiopathic pain, is
CHRIS PASERO
38
not associated with a known cause and often has a longer
duration than incident pain. End-of-dose failure, the last
of the subtypes, is characterized by a return of pain before
the next analgesic dose is due. The occurrence of increased pain at the end of the scheduled dosing period
suggests a need to maintain a higher plasma drug concentration throughout the dosing interval.13 In these cases,
the dose of the scheduled analgesic should be increased,
or in some patients the interval between doses should be
shortened, which ultimately results in an increased dose.
End-of-dose failure is seen in some patients receiving
intravenous PCA postoperatively who make multiple
unsuccessful attempts to obtain a PCA dose. Often, their
pain can be improved dramatically by shortening the
lockout (delay interval), eg, from 10 minutes to 6 to
8 minutes.
Although much about the epidemiology of breakthrough
pain remains to be elucidated, some early data strongly
suggest that, if not addressed adequately, breakthrough
pain can have significant negative effects on function
and quality of life.17-19 One study also indicated that the
presence of breakthrough pain in U.S. cancer patients increases the economic burden for patients and the health
care system.16
Treatment of Breakthrough Pain
The routine treatment of breakthrough pain is considered,
in general, to be conventional practice in populations for
which opioid therapy is the mainstay for the long-term
management of moderate to severe pain—specifically
those with active cancer or other types of advanced
medical illness.
Addressing the cause of breakthrough pain can eliminate
the need for analgesic therapy in some patients.13 For example, surgery, chemotherapy, or radiation therapy in
some cancer patients may eliminate the cause. Adjusting
the scheduled analgesic regimen, such as by increasing
the dose, is another approach that targets cause.
A variety of analgesic interventions may be considered to
treat breakthrough pain.13 Nonsteroidal anti-inflammatory
drugs can be used, based on an analysis of the patient’s risk
for adverse gastrointestinal or cardiovascular risk. More often, a short-acting mu agonist opioid is selected and provided on a PRN basis.13 If a patient is taking a modifiedrelease formulation for control of baseline pain, a short-acting formulation of the same drug as the modified-release
formulation is often selected. For example, short-acting
oral morphine is prescribed for breakthrough pain in
patients taking modified-release morphine. Similarly,
a short-acting oral or oral transmucosal opioid may be prescribed when baseline pain is treated with transdermal
fentanyl.
PRN Dosing
PRN dosing requires patients to request analgesia. Effective PRN dosing relies on the patient’s active participation. Patient teaching must include reminding patients
to ‘‘stay on top of pain’’ and request analgesia before
pain is severe and out of control. Obviously crucial to
the effective use of PRN dosing is a rapid response to
reports of pain and to requests for an analgesic.
In addition to its use for breakthrough pain, PRN dosing
of opioid analgesics may be appropriate for other types
of pain, such as intermittent pain. It is also useful when
initiating opioid analgesic therapy in opioid-naı̈ve patients with moderate to severe persistent pain, especially when pain is escalating rapidly. In these cases,
PRN dosing allows for a rapid response to the patient’s
need for pain relief while minimizing the chance of
overdose. PRN dosing is also helpful when pain is decreasing rapidly. When patients with acute pain recover
and pain resolves, ATC dosing may be replaced with
PRN dosing.
Although PRN dosing may be effective in these scenarios,
there is abundant clinical experience suggesting the potential for negative outcomes. As mentioned before,
some research has shown that overall adherence rates
for those who take PRN analgesics are poor compared
with those who take ATC analgesics for persistent cancer
pain.2 When PRN dosing is used in the inpatient setting,
patients may be reluctant to ask for pain medication for
a variety of reasons20 and request it only when pain is severe and out of control despite instructions to stay on top
of the pain. After the patient’s request, the nurse must
check the record to ensure enough time has elapsed since
the last dose the patient received; then the nurse must obtain and prepare the analgesic and, if it is an opioid, account for removal of the drug from the drug security
system. These activities are time consuming and result
in further loss of pain control.
Research shows that the most vulnerable of patients are at
high risk for undertreatment of pain when the PRN approach is used for continuous pain. A study of older adults
hospitalized for hip fracture, a condition associated with
moderate-to-severe pain, found that most of the analgesics
were prescribed for PRN administration and the nurses
were unaware that ATC administration of PRN-prescribed
analgesics would be preferable for this type of pain; only
22.3% of the patients received ATC analgesic administration of the PRN analgesics, and less than 25% of the minimum morphine equivalents of the opioids prescribed
were administered.21 Patients with dementia received significantly less pain medication than those without dementia, and eight patients with dementia in this study
received no opioid at all during the first 72 hours after admission.22 It is important for nurses to recognize that
PAIN CARE
39
PRN-prescribed analgesics may be administered ATC
within the parameters of the PRN prescription and that
this is the preferred dosing method for patients with con-
tinuous pain. Because there are so many disadvantages to
PRN dosing, the appropriateness of its use should be evaluated carefully in all cases.
References
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Hanks G, Cherny NI, et al, eds. Oxford Textbook of Palliative Medicine,
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3. Pasero C, McCaffery M. Safe use of continuous infusion with IV
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Calendar of Events
October 7, 2010. FLASPAN Preconference.
October 8-10, 2010. FLASPAN's 41st Annual Conference "Humanity & Technology in
Harmony...The Future of Perianesthesia Nursing." Regal Sun Resort, Lake Buena Vista,
Florida. Contact Emma Pontenila at [email protected] for further information.