American Society of Regional Anesthesia and Pain Medicine November 2017 - 33

Table 3: Analgesic selection and dosing in the presence of renal or hepatic impairment.
Drug

Renal failure

Hepatic failure

Avoid meperidine,* dextropropoxyphene

Avoid mepiridine

Likely should avoid morphine,** hydromorphone, codeine***

Likely should avoid methadone

Dose adjust tramadol, methadone

Dose adjust tramadol, dextropropoxyphene

No adjustment needed for fentanyl, oxycodone, bupernorphine

No adjustment needed for fentanyl, morphine

Local anesthetics

No adjustment needed

May need to adjust dose if prolonged use

NSAIDs

Avoid in severe renal impairment

Reduce dose

Acetaminophen

No adjustment needed

Avoid or reduce dose

TCAs

Metabolite accumulation may increase risk of side effects

Not enough data

Anticonvulsants

Gabapentin should be dose adjusted based on creatinine
clearance

Avoid carbamazepine, valproate

Ketamine

No adjustment needed

Not enough data

Opioids

* Active metabolite normepiridine can lead to neurotoxicity.
** Active metabolites morphine-6-glucuronide (M6G) and morphine-3-glucuronide (M3G) may cause myoclonus, seizure, hyperalgesia, allodynia.
*** Prodrug of morphine can lead to M6G and M3G accumulation.

Aside from difficult assessment of pain in the critically ill patient,
there are many other obstacles to pain management in the ICU
patient.
1. Impaired Renal and/or Hepatic Clearance
Critically ill patients often have organ failure with associated
decreases in renal or hepatic clearance; thus, drug choice
and dosing should be carefully considered. Table 3 reviews
considerations of analgesic selection and dosing in the presence of
renal or hepatic impairment.
2. Hemodynamic Instability
Patients in ICUs are often hemodynamically unstable. Hypotension
after the use of opioids is generally due to blunting of sympathetic
responses and may unmask hypotension. For this reason, bolus
doses should be administered slowly, and short-acting opioids are
preferred.
3. Obstacles to Regional Anesthesia
Regional anesthesia may be considered as an adjunct to decrease
opioid consumption in the critically ill surgical patient. However,
coagulopathy of the critically ill and anticoagulant medications
should be considered carefully prior to the implementation
of regional anesthesia.22 In addition, systemic infection and

positioning challenges (eg, fractures and an inability to cooperate)
may preclude safe neuraxial or peripheral nerve blockade. The
SCCM makes no recommendation for neuraxial/regional analgesia
over systemic analgesia in medical ICU patients due to lack of
evidence, but they do acknowledge thoracic epidural superiority
over parenteral opioids for abdominal aortic surgery.20
4. Pharmacologic Side Effects
Drug side effects may slow recovery, worsen patient outcomes, or
create new issues. Opioids can contribute to ileus, delirium, and
respiratory depression. It is generally accepted that patients with
long-term exposure to high-dose opiates may develop physiologic
dependence.
Intravenous opioids are first-line therapy for non-neuropathic pain.
Opioids may be administered by the patient's RN on a scheduled or
as-needed basis, but they may also be administered using patientcontrolled analgesia (PCA), in which the patient is given the ability
to self-administer pain medication. Any opioid can be administered
by PCA pumps; however, meperidine is not recommended for repeat
dosing because it lowers the seizure threshold and has a dysphoric
effect.23 In general, basal infusions are not recommended, but they
may be appropriate for opioid-tolerant patients and select patients
in the ICU. PCA may not be appropriate for a substantial portion

American Society of Regional Anesthesia and Pain Medicine
2017

Table of Contents for the Digital Edition of American Society of Regional Anesthesia and Pain Medicine November 2017