Page 299 Guide to Pain Management in Low-Resource Settings

Pain Management in the Intensive Care Unit 287

For less severe pain, pethidine and tramadol What nonopioid analgesics are options
could be used. Pethidine/meperidine could be given by for analgesia in the intensive care unit?
bolus doses for procedural pain relief, but not as an in- Nonopioid analgesics used in combination with an
fusion, because its metabolite can accumulate and is as- opioid achieve better-quality pain relief. Although
sociated with twitching and seizures. Tramadol has the some intravenous and intramuscular preparations are
advantage of two mechanisms of action for pain relief— available, these agents are mostly given by the enteral
opiate-like activity by binding to opiate receptors and route if gastrointestinal function permits adequate ab-
inhibition of serotonin and norepinephrine reuptake by sorption. Some are available in suppository form or as
nerves, mainly in the spinal cord. It is relatively expen- a liquid suspension, which can be given down a naso-
sive but avoids the problems of respiratory depression gastric tube.
and gastrointestinal stasis. Rapid intravenous injection Paracetamol/acetaminophen is a non-narcotic
may cause seizures, and it is not advised in pregnancy analgesic with useful antipyretic action as well. It is
or breastfeeding. useful in mild to moderate pain and has an additive ef-
Buprenorphine and pentazocine are unsuited fect if given with an opiate. It is available as dispersible
for analgesia in intensive care. If given in a suffi cient tablets, as an oral suspension, and in suppository form.
dose to cause respiratory depression, they are not reli- It has no anti-infl ammatory activity and so avoids the
ably reversible with naloxone. In addition, these agents side eff ects of nonsteroidal anti-infl ammatory drugs
antagonize other opioids because of powerful receptor (NSAIDs). Clonidine, an alpha-2-adrenergic agonist,
binding, reversing the analgesic eff ect of other opioids can be used to augment both the sedative and analge-
by displacing them from receptors. Th us, they may sic eff ects of opioids. A dramatic reduction in opioid
precipitate opioid withdrawal symptoms and signs. requirements and the attendant side eff ects has been
Pentazocine can be associated with bizarre thoughts reported with low-dose clonidine. Diclofenac, ketopro-
and hallucinations. fen, ibuprofen, and other NSAIDS are good for bone
Other opioids include meptazinol and codeine. pain and for soft-tissue pain in young patients without
Meptazinol is claimed to cause less respiratory depres- asthma or renal impairment and can reduce opioid re-
sion, but it can cause nausea. Intravenous injection quirements. Oral, nasogastric, intravenous, and rec-
needs to be slow. Codeine is used in mild to moderate tal routes can be used. Regardless of route, they cause
pain and might have some eff ect as a cough suppres- gastric irritation. Hence, prophylactic treatment for
sant. It is usually given orally, though linctus could be gastric ulceration should be given. However, the signif-
given down a nasogastric tube. Actually, codeine is me- icant side eff ects of NSAIDs in intensive care have to
tabolized in the liver into morphine and other products be considered: they can cause bronchospasm, may pre-
that cause relatively severe side eff ects. cipitate or exacerbate a bleeding tendency, cause gas-
trointestinal bleeding from mucosal ulceration (exac-
How to reverse the eff ects of opioids
if necessary erbated by platelet inhibition), or lead to development
of renal impairment or worsening of renal failure,
Naloxone reverses all opioid eff ects, so both respira-
particularly when other risk factors are present, such
tory depression and pain relief are reversed (for bu-
as hypotension, hypertension, or diabetes. NSAIDs
prenorphine and pentazocine, see above). Too much
should be used with caution in older patients due to
naloxone given too quickly and reversing analgesia
a higher incidence of gastric complications and renal
may result in restlessness, hypertension, and arrhyth-
impairment. Aspirin, indomethacin, and cyclooxygen-
mias and has been known to precipitate cardiac ar-
ase (COX)-2 inhibitors are not recommended for use
rest in a sensitive patient. If possible, dilute naloxone
in the ICU due to a plethora of side eff ects.
to 0.1 mg/mL and titrate, giving 0.5 mL of the diluted
solution at a time to achieve the required degree of re- What about using ketamine
versal, so that respiration becomes adequate and some in the intensive care unit?
analgesia continues. Naloxone has a shorter duration Good analgesia can be achieved with low-dose ket-
of action than many opiates, and the patient may be- amine. It tends not to be used for background analgesia
come renarcotized. Repeat doses of naloxone or an in- in intensive care in the United Kingdom, though it may
fusion may be required. be used for short procedures. Some studies have shown