7.5/325
10/325
Acetaminophen
7.5/325
Codeine
Oral analgesics are most effective for mild to moderate pain. The World Health Organization Pain Ladder recommends non-opioid analgesics for mild pain and a weak opioid or weak opioid/non-opioid combination for moderate pain.[17] If patients are to be discharged with a prescription for a particular oral analgesic, that medication can be started in recovery. Otherwise an oral analgesic can be selected taking into account pain severity and patient-related factors such as allergies and co-morbidities. Oral analgesics have a range of effectiveness and significant patient-to-patient analgesic variability. Of note, codeine 60 mg, a frequently prescribed weak opioid, while an excellent antitussive agent is a poor analgesic when not used in combination with acetaminophen. Given the availability of other more effective agents, codeine should not be used for analgesia in the PACU.
Overall, there are numerous different oral medications, both as single or combination agents. One recommendation is to administer analgesics as single agents rather than in combination for increased flexibility in dosing. For example, oral non-opioids can be given as scheduled dosing while oral opioids are used for breakthrough pain. On the other hand, a benefit of combination agents is that they take advantage of the synergistic analgesic effect of combining opioids and non-opioids such as acetaminophen and oxycodone. An important note on combination agents: a downside of combination pills, while convenient, is that many non-opioids such as acetaminophen and ibuprofen have important toxicity limits that should be avoided. Many patients can unwittingly overdose on these non-opioids at home as they add these combination pills to their prior non-opioid regimen.
Regional analgesia in the PACU
As the 2012 ASA Task Force on Acute Pain Management guidelines clearly emphasize a multimodal approach to analgesia in the perioperative setting, regional analgesia has a clear role in reducing postoperative pain in the PACU and should be employed whenever possible.[18] It is well documented, especially in the orthopedic population, that regional analgesia is superior to opioids in managing pain postoperatively. For instance, brachial plexus continuous peripheral nerve blockade (CPNB), when used in the inpatient and outpatient setting, has demonstrated prolonged pain control of up to 72 hours, less opioid use, faster resumption of physical therapy, fewer sleep disturbances, and overall increased patient satisfaction.[19] Similar results have been demonstrated for the various types of regional analgesia when compared with opioids.
While the majority of regional anesthetics are performed preoperatively to assist in intraoperative pain management, it is imperative to assess the quality of the regional blockade in the PACU in an expedient manner and have a low threshold for rescue blockade following a block failure. Each patient who has received a regional anesthetic, including brachial plexus, lumbar plexus, femoral, saphenous, sciatic, and transversus abdominis plane block, should be assessed for adequacy of sensory as well as motor blockade and an overall pain assessment upon arrival in the PACU. If a continuous catheter is in place and the block is determined inadequate, a 10 ml bolus of ropivacaine 0.5% (or alternatively bupivacaine 0.25%) should be administered via the catheter, as an increase in volume and local anesthetic spread may sufficiently improve the block. If the bolus proves unsuccessful or the patient received a single-shot peripheral nerve blockade, a repeat block should strongly be considered. However, in the event of extensive surgery or combination peripheral nerve blockade, it is imperative to properly delineate the distribution of pain to appropriately determine which block may be necessary.
Familiarity with the different types of peripheral nerve blocks is essential as well. For instance, the interscalene approach of a brachial plexus block provides good analgesia following shoulder surgery, but a common complaint encountered in the PACU is persistent axillary pain. In order to properly address such pain, the provider must be familiar with the distribution of the brachial plexus, which encompasses C5–T1 nerve roots, while the dermatome of the axilla is innervated by the intercostobrachial nerve (T2) and is therefore missed. Treatment of persistent axillary pain may be achieved by a supplemental intercostobrachial nerve block or supplemental opioids. As the benefits of regional analgesia have clearly been documented in published research and its utilization continues to increase, familiarity with the various types of peripheral nerve blockade is essential in the postoperative setting.
With improving technology and the increasing utilization of ultrasound, the use of continuous peripheral nerve blockade is on the rise specifically with regards to ambulatory catheters. Interscalene, infraclavicular, and popliteal catheters have all been shown to lower pain scores at rest and with movement as well as lower oral opioid analgesic use.[20] However, when utilizing ambulatory catheters it is important to use a dilute solution of local anesthetic, such as ropivacaine 0.2% at a rate of 4–10 ml/hr depending on location, to maximize sensory blockade while minimizing motor blockade as well as the risk of local anesthetic toxicity. Patient selection and education is imperative and detailed discharge instructions with contact information and emergency instructions must be provided.
Managing epidural catheters in the PACU
Common reasons for epidural failure include incorrect placement, inadequate infusion, and migration of catheters.[21] Failure rates as high as 32% for thoracic epidurals and 27% for lumbar epidurals have been previously reported.[22] The management of patients with thoracic and lumbar epidurals requires close supervision by a dedicated acute pain management team.
Prior to usage, all epidural catheters should be given a test dose to rule out intrathecal or intravenous placement. In instances when the patient is given a combined spinal–epidural (CSE) for surgical anesthesia, the test dose should be given after resolution of the spinal anesthetic since an intrathecal placement of the catheter can be missed. A common test entails aspirating the catheter for continuous blood or cerebrospinal fluid flow; however, this test has a high false-negative rate. Once negative flow is confirmed, a test dose of 2% lidocaine with dilute epinephrine (10 mcg/ml) can further rule out a misplaced epidural catheter. Epinephrine, as an additive to a test dose, functions as a marker of intravascular catheter placement. Epinephrine will cause an increase in heart rate and blood pressure with intravascular locations of the catheter. However, this test is insensitive and false negatives can occur. Other symptoms of intravascular injection of test dose include perioral numbness, tinnitus, vertigo, and rare seizures.
An infusion of local anesthetic can be started at a rate of 10–14 ml/hr after ruling out intrathecal and intravascular placement of an epidural catheter. The ideal concentration and local anesthetic agent depend on the desired differential block. Most institutions utilize dilute ropivacaine (0.1%, 0.2%) or bupivacaine (0.15%) to minimize motor block and maximize sensory blockade. The main quality of analgesia is determined by the total dose of local anesthetic, which is dependent on both rate per hour and concentration. The addition of opioids (e.g. fentanyl, sufentanil, dilaudid) to the local anesthetic can allow for reduction in local anesthetic dose and increasing patient comfort. Epinephrine can be added to epidural infusion to decrease systemic absorption of local anesthetic. Epinephrine also binds to α2 adreno receptors, resulting in anti-nociceptive effects on the spinal cord.[21]
Postoperative control of pain in the PACU entails a multimodal approach. Clinicians will need to be familiar with IV opioids and non-opioids. Additionally, many ambulatory patients can be prescribed oral analgesics, which can be initiated in the PACU. Regional anesthesia with its benefits and risks can aid in improving analgesia, reducing opioid side effects, and decreasing overall PACU stay. A multimodal approach that combines the previously mentioned techniques will assist in improving patient care in the PACU.
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