ACUTE PAIN MANAGEMENT Background Info
LHSC - Victoria Hospital & University Hospital
Table of Contents
APOOR Rotations at Victoria Hospital
1. Introduction to the Acute Pain Service
Structure of APS Team at LHSC
Priorities of APS Rounds
What to look for during APS Rounds
2. Pharmacological Principles
Postoperative Pain Management Strategy
Analgesic Foundation
Acetaminophen
NSAIDs
Tramadol
3. Patient-Controlled Analgesia
Troubleshooting problems with PCAs
HOW TO CALCULATE THE APPROPRIATE IV PCA DOSE
During the Transition Phase of Postoperative Care
4. Opioid Conversion
5. Analgesic Adjuvants
Anticonvulsants
Antidepressants - TCA
Non-analgesic Adjuvants
Ketamine
Intravenous Lidocaine
Antiemetics
Antipruritics
6. Epidural Catheter Infusion
Epidurals: Problems and Actions
7. Peripheral nerve and plexus catheter infusion
8. Special cases
Methadone maintenance therapy (MMT)
Buprenorphine maintenance therapy (BMT)
Chronic kidney disease (CKD)
Dosage guidance for analgesics and adjuvants used in renal insufficiency
Complications of NSAIDs in patients with ESRD
Opioid Safety in patients with ESRD
Suboxone
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References
Contributors
Heather Whittle
Charlotte McCallum
Dr. Kevin Armstrong
Dr. Bill Lin
Dr. Kate Ower
Dr. Qutaiba Tawfic
Compiled by Dr. J. Vergel de Dios | Updated June 18, 2018
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APOOR Rotations at Victoria Hospital
APOOR = Acute Pain Service (APS) & Out-of-OR (OOR) rotation
For about 2 weeks you will be assigned to APS at Victoria Hospital and the other 2 weeks will be clinical assignments
outside of the OR.
For the APS portion:
1) At the beginning of the rotation, ensure you have access to the APS in-patient lists in PowerChart. Please contact
Heather Whittle (VH) and/or Charlotte McCallum (UH) to acquire access.
2) Contact the respective APS staff the day before to receive information on the daily start time and location as this
3) can vary according to each staff. Consultants are assigned on a weekly basis to APS.
4) At the beginning of each day, ensure the APS pager number has been forwarded to your personal pager number to
ensure APS consults are received appropriately.
Daily responsibilities include rounding on APS in-patients, charting APS assessments and modifying in-patient order sets on
Powerchart, updating the APS in-patient list, covering any in-patient APS or preoperative consultations received from
0800-1600h, and attending any out-of-OR procedures scheduled for the day. If time allows, it is expected that the APS
resident will assist in the Pre-Admission Clinic.
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1. Introduction to the Acute Pain Service
The Role of APS
❖ A consult service available around the clock in cases of severe acute pain.
❖ Provide quality pain management for perioperative patients on a daily basis.
❖ Collaborate with surgeons, nurses, and other health care providers to hasten surgical patient mobilization and
recovery.
❖ Provide educational opportunity to residents, fellows and nurses.
❖ Monitor and document patient outcomes.
❖ Improve patient awareness about pain management
❖ Audit the cost effectiveness of pain management for surgical patients.
❖ Apply and study new pain methods and medications for pain management
❖ Review and update acute pain management protocols.
❖ Increase research opportunity.
Structure of APS Team at LHSC
Director of APS - Dr. Kevin Armstrong
UH Site Coordinator - Dr. Qutaiba Tawfic
Vic Site Coordinator - Dr. Kate Ower
APS staff anesthesiologist
APS staff anesthesiologist - rotates weekly
UH APS nurse practitioner (NP)
VH APS nurse practitioner (NP)
Charlotte McCallum
Heather Whittle
Clinical Fellow
Clinical Fellow
APS Resident
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Priorities of APS Rounds
1.
2.
3.
4.
5.
Identify patients with challenging situations regarding pain management.
APS patients receiving epidural infusions of local anesthetic/opioids.
Patients with continuous regional analgesia.
Patients with ongoing analgesic management strategies.
Patients with recent changes to analgesic management.
What to look for during APS Rounds
❏ APS medication administration record, e.g. MAR, PCA and regional analgesia pump review, hourly and total
PCEA/PCRA.
❏ VAS or NRS (NRS at rest should be ≤ 3 and the NRS active ≤ 6). This may not be applicable for chronic pain
patients.
❏ Consider pre-procedure pain score and location of pain.
❏ Effectiveness of interventions (oral/parenteral medications, non-pharmaceutical).
❏ Side effects and/or complications.
❏ Suitability for transition from interventional modes (PO status, opioid requirements).
❏ Review planned surgical orders for analgesia after APS discharges the patient.
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2. Pharmacological Principles
The World Health Organization (WHO) proposed an analgesic ladder in 1986 for a better stepwise control of cancer pain.
This ladder has become the basis on which many APS strategies are built.
1. THE FIRST STEP to treating mild pain includes non-opioid medications like acetaminophen, non- selective non-steroidal
anti-inflammatory drugs (NSAIDs), and the cyclooxygenase type 2 (COX-2) inhibitors. The first step of the ladder
represents the foundation upon which all other steps are going to be layered.
2. STEP TWO of the ladder involves treating moderate pain or pain persisting beyond step one. Tramadol, tapentadol and
low doses of regular opioids are among the choices of this step.
3. IN STEP THREE, higher doses of potent opioids are added for severe pain and pain persisting beyond step two.
At any stage of the analgesic ladder, there are analgesic adjuvant medications that can be added such as the
gabapentinoids, antidepressants, NMDA, receptor antagonists, intravenous lidocaine and alpha 2 agonists.
We anticipate that the majority of postoperative patients are within the range of moderate to severe pain at some
point in their care. So, our APS orders should be based on this assumption.
The electronic orders available for the APS have more commonly used medications, and doses which are on the
lower side to reduce consequences of high dosages. However, errors, and adverse events are possible.
Please check your orders!
Postoperative Pain Management Strategy
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Neuraxial or peripheral nerve blocks whenever possible
Mild pain:
acetaminophen + NSAIDs ± tramadol
Moderate pain: acetaminophen + NSAIDs + tramadol (± other opioids)
Severe pain:
acetaminophen + NSAIDs + tramadol + other opioids
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Perioperative gabapentin or pregabalin as adjuvants in selected cases like trauma, neuropathic pain, or chronic
pain
Analgesic Foundation
Acetaminophen and NSAIDS - first on and last off
❖ It is effective for 50% of patients with moderate to severe postoperative pain for 4-6 hrs following various types of
surgery
❖ Reduces opioid consumption by 35% to 75%
❖ Acetaminophen’s morphine-sparing effect less than NSAIDs
❖ There is evidence that combining acetaminophen and NSAIDs may result in superior analgesic quality in
comparison to either drug alone
Acetaminophen
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Low incidence of side effects; however, it is the most common cause of acute liver failure in children due to
accidental poisoning.
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Toxic doses >150 mg/kg dose in children and >7–10 gm/dose in adults.
ADULTS
PEDIATRICS
CONTRAINDICATIONS & PRECAUTIONS
975 mg PO q 6h or 650 mg PO q 4h
PO: 10 - 20 mg/kg q 4-6h
Maximum single dose of 975 mg
Minimum dosing interval of 4 hours
Maximum daily dose of 4 grams
Consider dose reduction in elderly patient
PR: 30 - 40 mg/kg loading dose,
then 20 mg/kg PR q 6h
Severe hepatic impairment
Severe active liver disease
Known allergy to acetaminophen
Alcoholism
Chronic malnutrition
NSAIDs
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They inhibit both peripheral and central cyclooxygenase (COX) production and reduce prostaglandin
formation.
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The triad of NSAIDs, hypotension and angiotensin converting enzyme inhibitors (ACEI) can severely impair
the GFR and renal function.
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Though they are considered to be nonspecific analgesics and can be helpful in any type of pain, pain associated
with inflammation is more likely to be responsive.
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Although selective COX-2 inhibitors provide analgesia that is not superior to the non-selective NSAIDs, they may
have a lower risk of gastrointestinal side effects and less effect on platelets. Cox-2 selective inhibitors may be of
benefit when there is a risk of surgical bleeding, but may promote thrombotic events.
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In general, there is no clear evidence that one NSAID is superior to other in postoperative pain control.
ADULTS
PEDIATRICS
CONTRAINDICATIONS & PRECAUTIONS
Ibuprofen
400 mg PO q 6h
Max 2400 mg/day
Ibuprofen
5 - 10 mg/kg PO q 8h
Max 2400 mg/day if > 12 yo
Infants 6 mos to < 12 yo, max daily dose is 40 mg/kg or
2400 mg/day (whichever is less)
Known allergy to any type of NSAID
GI ulcer or bleeding
Renal impairment
Bleeding diathesis
Cardiovascular impairment
3rd trimester pregnancy
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Naproxen
250 - 500 mg PO q 8h
Max 1000 mg/day
Naproxen
10 - 20 mg/kg PO q 12h
Max 1000 mg/day
Ketorolac
10 - 30 mg IV q 6h prn
Max 120 mg/day
10 mg PO q 6h
Ketorolac
0.5 mg/kg IV q 6-8h prn
0.5 mg/kg (> 20 kg) or 10 mg (for > 20 kg) PO q 6-8h.
Max 40 mg/day.
Some surgical procedures, e.g. bone
fusions, ENT, bowel anastomosis, bone
grafts, any flap procedures.
Need to check with surgical team if
NSAIDs are highly required.
Consider duration of prescription, or
number of doses as strategy to reduce
adverse events.
Tramadol
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Tramadol has been used widely to treat moderate severity acute pain.
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It has weak opioid agonist activity in addition to serotonin (5-HT) and norepinephrine reuptake inhibition.
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It needs to be metabolized in the liver by the CYP2D6 enzyme into an active metabolite (O-desmethyl
tramadol).
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Individuals who have CYP-2D6 enzyme polymorphisms (10 - 20% of the population) are at risk of failure of
analgesia.
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Tramadol may be a logical first choice in step 2 of the analgesic ladder.
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Nausea and vomiting are among the common side effects of tramadol and these side effects are
dose-dependent.
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Start with 25-50 mg po q6h. Daily recommended maximum dose for adult is 400 mg.
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Dosage reduction or increase in the dosage interval should be considered in cases of severe impairment in kidney
(creatinine clearance below 50 mL/min).
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Tramadol should be used cautiously in patients using other serotonergic medications like antidepressants
to avoid serotonin syndrome. Some of the more commonly used meds in this class are citalopram,
fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), trazodone, duloxetine (Cymbalta), venlafaxine
(Effexor) and tricyclic antidepressants.
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3. Patient-Controlled Analgesia
❖ Patient-controlled analgesia (PCA) has become a standard technique to provide opioids for effective and safe
acute pain management.
❖ Some patient-related factors like age, comorbidities, previous opioid usage and other psychological factors can
impact the dose ordered for each patient.
❖ Hydromorphone is “first-line” opioid for PCA. The concentration has been standardized as hydromorphone
0.5 mg/mL.
❖ Other solutions: Morphine 2 mg/mL and fentanyl 10 mcg/mL.
ADULTS - opioid naive
PEDIATRICS - opioid naive
Continuous/Basal Infusions
Dose
Hydromorphone 0.2 mg
Morphine 1 mg
Fentanyl 10 mcg
Dose
Morphine 0.03 mg/kg
Patients on chronic oral opioid therapy,
and who are NPO, should have their usual
opioid maintenance requirements via
continuous infusion until they are
tolerating their regular diet.
Delay 6 minutes, no basal infusion
The actual role of the basal infusion with
IV PCA is controversial. We generally do
not recommend the use of a basal rate in
opioid naive patients.
Delay 6 - 10 minutes
We recommend giving 50% of their usual
maintenance as a basal rate, and then
using a larger bolus dose.
STOP THE CONTINUOUS INFUSION IF
PATIENT APPEARS OVER-SEDATED or
HAVING NO/MILD PAIN AT REST.
Troubleshooting problems with PCAs
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Poor pain control may be defined as VAS scores > 3 at rest and > 6 with activity, scores are 0-10 for the
non-chronic pain patient.
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Comparing the cumulative demands to the cumulative successful attempts provides very useful
information. Generally the ratio should not be > 2:1.
Differential diagnosis:
1. Pain poorly controlled
2. Patient does not understand principles of PCA and needs re-education
3. Patient may be confused, can’t remember and probably not a PCA candidate
4. Is someone else is pushing the button?
HOW TO CALCULATE THE APPROPRIATE IV PCA DOSE
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Use the opioid conversion chart to determine the oral morphine equivalent
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Consider opioid tolerant patient if ≥ 100 mg PO morphine/day
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Calculate the shift of the opioid dose response curve factor as equal to daily oral morphine equivalence divided
by 100. For example, a patient taking 500 mg per day of oral morphine preoperatively has approximately a
fivefold (500/100 = 5) increase in opioid requirement and would require a 5 mg morphine PCA bolus dose.
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However, it is advised to start the setting with 50-60% of the calculated dose (2.5 - 3 mg morphine bolus dose)
and then titrate up gradually to 5 mg bolus if required.
During the Transition Phase of Postoperative Care
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Transition from regional and parenteral techniques to oral opioids/adjuvants;
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Allow as-needed use of a short-acting opioid every 2-3 hours in sufficient quantity to provide the remaining required
opioid dose
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Plan to taper from postoperative opioid doses toward preoperative doses and discuss with the patient and
outpatient care providers
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Determine whether there is a need for specialty follow-up if the regimen is particularly complex.
PCA TRANSITION TO ORAL ANALGESIC THERAPY
» STEP A: D/C the continuous infusion when the patient has mild to no pain at rest.
» STEP B: Transition to PO analgesic if the patient is tolerating PO fluids and not requiring frequent
bolusing for activity.
» STEP C: Check the surgical team pain and symptom management orders and alter existing order, or
provide ‘Suggest’ orders before signing off the patient from APS.
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4. Opioid Conversion
Rule of 10 --- 5 --- 2.5 --- 2
NB: Oxycodone-morphine equivalence according to the Canadian guideline for the use of opioids for chronic noncancer pain 2010 is (30/20).
PO TO IV 4:1,
PO TO SC 3:1
IV TO PO 1:2
Whenever possible ask the nurse to start with PO short acting opioids before jumping to SC opioids.
This is a good link: http://www.globalrph.com/opioidconverter2.htm
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5. Analgesic Adjuvants
Anticonvulsants
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Gabapentinoids (gabapentin and pregabalin) are the most frequently used anticonvulsants as adjuvants to treat
acute pain.
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The precise mechanism of action of gabapentinoids is not fully understood. However, the main site of action is
believed to be α-2 ẟ sub-unit of pre-synaptic, voltage-dependent calcium channels, which are widely distributed
throughout both the peripheral and central nervous system.
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They are approved for neuropathic pain and acute postoperative pain
Bioavailability for pregabalin 90% and gabapentin 28-65%
Elimination: Renal (92-99% unchanged)
Dosing Schedule BID/TID
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We always start with a small dose 25-50 mg BID/TID for pregabalin
For gabapentin, 100 mg BID/TID is a safe start for the elderly, but 300 mg BID/TID is fine for a young and healthy
individual
Pregabalin is non-formulary in LHSC. For patients on pregabalin at home it can be continued in hospital
A 50% reduction in patient with creatinine clearance between 30-60 mL/min
Side-effects: Somnolence, dizziness, dry mouth, peripheral edema, blurred vision, weight gain and
abnormal thoughts.
Indications
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Poor pain control
Patient with history of chronic pain
History of opioid dependence
Postoperative pain with
hyperalgesia (neuropathic pain)
Preoperative pregabalin/ gabapentin use
Procedures with a high risk of
chronic neuropathic pain e.g
thoracotomy, spine surgery
Precautions
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Obstructive sleep apnea
Renal insufficiency
Elderly (age > 70 years)
Neuraxial opioids (especially in the
elderly)
Antidepressants - TCA
Nortriptyline
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Used for chronic neuropathic pain, but can be helpful for acute neuropathic pain, as well.
It inhibits the reuptake of pre-synaptically released norepinephrine (NE) and serotonin (5HT).
It can improve sleep pattern in pain patients.
Typical initial dose: 10-25 mg PO qhs. Increase by 10-25 mg every 1-4 weeks according to tolerance.
Precautions
Suicidal ideation and behavior
Cardiovascular disorders- may increase risk of sinus tachycardia, cardiac conduction time changes, arrhythmias,
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myocardial infarction (MI), and stroke
Glaucoma
Hyperthyroidism
Schizophrenia
Urinary retention due to the anticholinergic effects
Other agents which involve inhibition of norepinephrine (NE) and/ or serotonin (5HT)
Non-analgesic Adjuvants
Sedation
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Trazodone 25 – 50 mg PO qhs prn appears to be safe and is associated with minimal complications.
Ativan on PRN basis can be used as sedative, hypnotic, muscle relaxant and anxiolytic.
Sleep disturbance is not uncommon after surgery even when pain is effectively treated. Sedatives and
tranquilizers can help those patients to reduce their anxiety and improve their sleep, especially if they were taking
some of these medications before surgery. This can also help in reducing the chance of using opioids (PCA or
PO) for sleep instead of treating pain. However, we should remember that sedatives may augment the opioids
risk of respiratory depression.
Some factors should be assessed before ordering sedatives or sleeping pills e.g. current level of sedation,
presence of obstructive sleep apnea /morbid obesity, existing use of other sedatives and patient’s age.
Ketamine
Ketamine has the following characteristics:
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It is a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptor
Has been widely used in anesthesia and pain management
Potent antidepressant
Administered orally or intravenously (small boluses, continuous infusion or added to opioids in PAC)
Low-dose ketamine improves postoperative and posttrauma pain scores and reduces opioid consumption
It has special indication for patients with opioid tolerance, acute hyperalgesia, and neuropathic pain
It also has a role in the management of chronic pain in both cancer and noncancerous patients
Work is currently underway for the addition of ketamine in the APS at LHSC
Intravenous Lidocaine
Lidocaine is an amide local anesthetic which when used intravenously demonstrates significant analgesic, antihyperalgesic and anti-inflammatory properties.
It also reduces the sensitivity and activity of spinal cord neurons, decreases N-methyl- D-aspartate (NMDA)
receptors mediated post-synaptic depolarization.
The analgesic effects of systemic lidocaine were first tested in chronic neuropathic pain when the results support
the usage of these drugs.
Perioperatively, when lidocaine is administered as a continuous infusion at clinically relevant doses (1 - 2.5
mg/kg/hr) this results in plasma concentration which is adequate to attenuate sympathetic responses, decrease
pain and demonstrate a significant opioid sparing with minimal side effects.
Lidocaine has a direct stimulatory effect on intestinal smooth muscle. This effect may be due to the blockade of
inhibitory reflexes originating from the myenteric plexus. Also, its opioid-sparing effect may be another indirect
factor to improve bowel recovery and avoid ileus.
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Currently, we can use it across LHSC in monitored areas only such as the OR and PACU. We hope that we can expand this
service to other monitored units in the near future as long as telemetry is possible. At Vic, monitored units are CCTC, CCU,
thoracics, vascular, and ENT floors, and the Trauma Observation Unit.
Antiemetics
Both pain and its treatments (especially opioids) are associated with nausea and vomiting.
With multimodal analgesia (MMA), not only is pain better controlled, but the reliance on opioids and hence their
side-effects are mitigated.
Ondansetron is considered a first line agent. It has an excellent side effect profile and is highly efficacious for both the
prevention and treatment of nausea and vomiting.
Other options include metoclopramide, dimenhydrinate (Gravol), and haloperidol.
ADULTS
PEDIATRICS
Ondansetron
Metoclopramide
Dimenhydrinate
4mg IV/PO q 4 - 6 h prn
10mg IV/PO q 4 - 6 h prn
25-50 mg IV/PO q 4 - 6 h prn
Ondansetron
Metoclopramide
Dimenhydrinate
0.1 mg/kg IV/PO q 4 - 6 h prn
0.1 mg/kg IV/PO q 4 - 6 h prn
0.1 mg/kg IV/PO q 4 - 6 h prn
Antipruritics
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The partial agonist/antagonist (hydroxyzine) is available for the treatment of neuraxial opioid induced
pruritus but not for parenteral opioid induced pruritus.
Naloxone is also helpful for neuraxial opioid induced pruritus.
Pruritus is much more common with IVPCA morphine than IVPCA hydromorphone.
Diphenhydramine (Benadryl) is sometimes required while the patient is on IV PCA.
ADULTS
Diphenhydramine
Naloxone
Hydroxyzine
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PEDIATRICS
25 - 50 mg IV/PO q 4-6 h prn
0.1 mg SC q 1h prn
25 - 100 mg PO/IM q 6h prn
Diphenhydramine
0.5 mg/kg IV/PO q 4-6 h prn
Hydroxyzine
0.5 mg/kg PO/IM q 6h prn
6. Epidural Catheter Infusion
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Epidural analgesia is a part of multimodal analgesia rather than a sole analgesic model
Avoid premature decisions about catheter failure
Avoid delay in trouble shooting non-functioning epidural catheter, and add adjuvant or use alternative mode of
analgesia
On the one hand, nothing is better than a functioning epidural and on the other, nothing is worse than a nonfunctioning epidural
Warn the patient to avoid walking if there is motor blockade of the legs until the block dissipates (more
likely with lumbar epidurals)
Stop the infusion at least 4 hours before catheter removal to be able to monitor any paresthesia or motor
weakness during and after catheter removal (warning signs)
Add other analgesics + adjuvants before discontinuing the infusion and the catheter (improve the chance
for a smooth transition)
INR must be 1.4 or less to discontinue the catheter. We generally remove the catheter 12 hour after the last dose
of prophylactic low-molecular weight heparin (LMWH) and restart dalteparin 4 hours after the removal of the
epidural catheter. Refer to the ASRA guidelines as the medications used for DVT prophylaxis change along with the
suggested guidelines.
An order is required to hold VTE prophylactic prior to removing the epidural catheter to reduce the risk of catheter removal
after administration.
Problems
Hypotension associated with epidural
Partial, unilateral or patchy block
Motor block
Catheter migration
Sensitivity or side effects from opioids in epidural solutions
Coagulation status
Systemic infection
Types of epidural solutions
Local anesthetic alone (bupivacaine)
Bupivacaine + fentanyl
Bupivacaine + hydromorphone
Standard Epidural solutions:
University Hospital: 0.1% bupivacaine with hydromorphone 10 mcg/mL (hydromorphone can be changed to 20 mcg/mL in
opioid dependent patient)
Victoria Hospital: 0.1% bupivacaine with 20 mcg/mL hydromorphone for adults and 0.1% bupivacaine with
hydromorphone 10 mcg/mL for pediatrics
University and Victoria Hospitals: 0.125% bupivacaine with fentanyl 2 mcg/mL
Pediatric rates
For bupivacaine, maximum infusion rate for neonates is 0.2 mg/kg/hour. Over age 6 months, 0.4 mg/kg/hour.
Loading volume: 0.05 mL/kg/ dermatome spread from catheter/needle tip.
At the caudal region, count up from the coccyx. For lumbar catheter, count segments in one direction from catheter
tip. Infusion rate: 0.2 - 0.4 mL/kg/hour, not to exceed typical adult infusion rates of up to 15 mL/hour.
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For thoracic catheters, use half the loading dose and half the infusion rate.
Things to assess
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VAS pain score at rest and on movement
Level of sensory block
Presence of motor block
Type of local anesthetic solution
Rate of infusion
PCEA use and effectiveness
Duration of epidural catheter (try to keep it 3 days maximum, in selected cases may leave it for 5 days with added
risk of infection. Need to discuss that with the patient and APS staff)
Symptoms of LA toxicity (lightheadedness, blurred vision, tinnitus, circumoral numbness, disorientation and LOC)
Side effects related to opioids added to the solution (excessive nausea, vomiting, pruritus, heavy sedation and
respiratory depression)
Dressing site: Look for bleeding, excessive leaking, catheter dislodgement, redness and infection.
Indicators of ongoing systemic infection
Coagulation status before catheter removal (as per the American Society of Regional Anesthesia and Pain
Medicine Guideline / 4th Edition 2018).
Epidurals: Problems and Actions
Somnolence, difficulty to arouse,
and hypoventilation
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Ensure airway patency, O2
supplementation, and vigorous
stimulus
Hypotension
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Check level of sensory block (high
block)
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Check fluid status
Fluid bolus if surgeon OK
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Assist with ventilation if required
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Ensure maintained blood pressure
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Consider patient’s preoperative
normal blood pressure
Careful titration of opioid antagonist
(naloxone 0.1 mg intermittent
boluses)
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Consider the possibility of
intrathecal catheter migration (rare
event)
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Check for inadvertent epidural
overdose
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Consider holding patients
anti-hypertensive medication, if on
any
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Check motor block: Absence of
motor block most probably rules out
the rare event of intrathecal
migration.
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Check for high level of sensory
blockade to cold perception
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Consider other causes for altered
LOC, i.e. other drugs, CVA,
metabolic, sepsis, etc.
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Reduce infusion rate and reassess
for blood pressure, sensory level
and VAS
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Consider alternatives for analgesia,
if the decision is to stop the
infusion
Significant weakness or motor
block
● Discuss this with your staff
● Withhold the infusion and review
after 30 min, then reduce infusion
rate
● If significant motor weakness present
in spite of withholding infusion, then
consult regional anesthesia or
neurology team or change local
anesthetic solution
● You may need to stop infusion and
consider alternative analgesic
modality if no improvement in motor
function after dose reduction
● If there is no improvement in motor
function after holding the infusion for
1 hour consider an MRI to rule out
epidural hematoma, especially when
other neurological symptoms are
present
7. Peripheral nerve and plexus catheter infusion
Continuous peripheral nerve block catheter analgesia is a part of multimodal analgesia (MMA) rather than a sole
analgesic model.
Warn the patient to avoid trauma to the weak and insensate limb (as pain sensation is blocked, injury can occur to vital
structures) e.g. for upper limb analgesia keep the weak and insensate arm in a sling, protect the elbow to prevent ulnar
nerve injury.
Warn the patient to avoid walking on the motor blocked leg until the block dissipates, or to do so with support, or under
direction of one qualified to assist.
Avoid premature decision about catheter failure.
Add other analgesics + adjuvants before discontinuing the catheter (smooth transition).
While on call, before deciding to remove a catheter consider holding the infusion (with suitable analgesia), and the
APS team can review in the morning.
Things to assess
● VAS pain score at rest and on movement
● Presence of excessive numbness and motor block altered sensation/motor function
● The presence of altered sensation can indicate the contribution of a regional technique to multimodal
analgesia
● Strength of local anesthetic solution (0.1 to 0.3% ropivacaine most common).
● Rate of infusion
● PCRA use and effectiveness
● Symptoms of LA toxicity (lightheadedness, blurred vision, tinnitus, circumoral numbness, disorientation
and LOC)
● Dressing site: Look for bleeding, excessive leaking, catheter dislodgement, redness and infection.
● Duration of nerve catheter (try to keep it 3 days maximum, in selected cases may leave it for 5 days with
added risk of infection. Need to discuss that with the patient and APS staff)
● Coagulation status before catheter removal if deeper block location (as per the American Society of
Regional Anesthesia and Pain Medicine Guideline / 4th Edition 2018).
Problems and actions
Poor pain control
Significant weakness or motor block
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Depending on the regional technique and the surgical
procedure, there may be sparing of some nerve
distributions. As such, consider regional techniques as part
of MMA.
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The presence of motor weakness may be
unavoidable depending on technique. Its
presence in lower limb is more significant than
upper limb.
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Increase infusion by 2-3 mL when VAS > 3 at rest or ≥ 6 at
movement, and review after 30 minutes
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Consider reducing /or withhold the infusion and
review after 30 min
●
Boluses of infusate (5-15 mL) may improve analgesia as
volume and spread can be a important aspect to
re-establish analgesia
●
●
If significant motor weakness present after
multiple dose reduction then consult regional
anesthesia team or change local anesthetic
solution
Repeat increase of infusion rate until VAS < 3 or until
maximum of 15 mL/h (consider maximal dosing for local
anesthetics)
●
You may need to stop infusion and consider
alternative analgesic modality if no improvement
in motor function
●
For persistent motor weakness and /or paraesthesia
●
If VAS still high with maximum infusion dose, consider
partial/complete failure of catheter technique and add
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another technique or consider alternative technique for pain
relief e.g. PCA or oral analgesia
after discontinuing the infusion you may consider
nerve injury. Inform regional anesthesia group
and/or neurology consult
8. Special cases
Methadone maintenance therapy (MMT)
Continue methadone as before on surgery day
Establish liaison with MMT physician or pharmacy
Preoperative anesthesia consult and investigations, especially ECG
Methadone is ordered by the MRP, which is the surgeon in most cases.
APS will ok that it is given but we do not order it.
DAY SURGERY: Resume regular methadone after surgery + additional analgesics for pain control
IN-PATIENT SURGERY: While NPO, alternative analgesic (Regional/PCA) + alternative opioid (e.g. morphine) /
Resume oral methadone ASAP when tolerated, if > 5 days off methadone, resume with advice of methadone
prescriber.
Opioid conversion of methadone to morphine = 1/10
Opioid conversion morphine to methadone (after 3 days of stopping methadone) = 4/1
Buprenorphine maintenance therapy (BMT)
Butrans Patch: 5-20 mcg/ hr every 7 days (Max is 20 Mcg/hr) Also suboxone for addiction is becoming more common
Options depend on the urgency of the surgical procedure:
1. FOR MAJOR ELECTIVE SURGERY.
Stop buprenorphine 72 hr before the surgical procedure and commence full opioid agonist (e.g. morphine or
hydromorphone). After 12- 24 hours, titrate the dose to control pre-existing pain.
Consider regional analgesia whenever possible.
Calculate the intraoperative and postoperative opioid based on the last preoperative dose of replacement opioid.
Maximize non-opioid analgesics.
2. EMERGENCY AND INTERMEDIATE OR MINIMAL ELECTIVE SURGICAL PROCEDURE
Continue buprenorphine Patch at current dose
Consider optimization of non opioid analgesics.
Consider regional analgesia whenever possible.
Consider higher doses of opioids (PCA/oral) if required in monitored place (start with 25% higher than the standard).
Chronic kidney disease (CKD)
DEFINITION: Patients with CKD should have either a glomerular filtration rate (GFR) less than 60 ml/min/1.73 m2 for ≥3
months or structural/ functional kidney damage with or without changes in GFR.
CHALLENGES:
Prevention of further renal damage e.g. NSAIDs can induce further damage.
Dose adjustment is required for many drugs in patients with significant drop in GFR.
Pre-existing chronic pain: Chronic pain is reported in 40-50% of hemodialysis patients and more than 80% of those
patients have experienced moderate to severe pain.
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Fluctuation in pain in hemodialysis patient due to wash out of some pain medications during dialysis.
https://www.kidney.org/atoz/content/gfr accessed April 2018
Dosage guidance for analgesics and adjuvants used in renal insufficiency
A. Analgesic foundation and opioids
Analgesic Agent
Patient at risk / early CKD
Advanced CKD
ESRD / hemodialysis
Acetaminophen
325 - 650 mg po q 4-6h
325 - 650 mg po q 4-6h
325 mg po q 4-6h
Tramadol
25 - 50 mg po q 6h
25 mg po q 6h
25 mg po q 8-12h
Morphine, codeine,
meperidine
Reduce dose
AVOID
AVOID
Hydromorphone (PO)
1 - 2 mg po q 4h
1 mg po q 4h
0.5 mg po q 4h
Hydromorphone (SC)
0.5 - 1 mg sc q 2-4h
0.5 mg sc q 2-4h
0.5 mg sc q 2h
PCA
Hydromorphone bolus
0.2 mg
0.1 mg
0.1 mg
Hydromorphone continuous
infusion
NO
NO
NO
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B. Antiepileptics - for neuropathic pain
Creatinine clearance
(mL/min)
Pregabalin
Gabapentin
> 60
25 - 100 mg po q 8h
300 - 1200 mg po q 8h
30 - 59
25 - 75 mg po q 8h
300 - 900 mg po q 8h
15 - 29
25 - 75 mg po q 12h
200 - 700 mg po q 12h
< 15
25 - 75 mg po daily
100 - 300 mg po daily
Hemodialysis
25 - 50 mg po daily
25 - 50 mg po supplement post-dialysis
100 - 300 mg po daily
100 - 300 po supplement post-dialysis
Complications of NSAIDs in patients with ESRD
●
●
●
●
Cause an irreversible decline in the residual renal function
Increases the risk of GI bleeding due to their effects on GI mucosa and platelet function
Potential cardiovascular risks
NSAID-related hyperkalemia
Opioid Safety in patients with ESRD
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Opioid
Recommendation
Fentanyl
Safe
Alfentanil
Safe
Hydromorphone
Safe, dose adjustment might be required
Morphine
Preferably avoid
Codeine
Avoid
Oxycodone
Not enough evidence
Suboxone
Suboxone is one brand of a combination of buprenorphine and naloxone. It is used for treating opioid addiction and chronic
pain. Buprenorphine is a partial opioid agonist/antagonist with a very long half-life and tight mu receptor binding. For those
on suboxone, treating post-operative pain with opioids is complicated by the high affinity of buprenorphine for the mu
receptor. This high affinity results in displacement of, or competition with, common opioid agonist analgesics when
suboxone is administered concurrently or sequentially. Therefore, the pharmacokinetic properties of buprenorphine
interferes with the effectiveness of concurrent administered opioids.
There is limited data to inform optimal acute pain management strategies for these patients and there is no clear
agreement on approaches for the perioperative management of patients on suboxone. A lack of clarity or good guidelines
can lead to poorly controlled pain and there is potential for serious adverse events in the preoperative period. Currently
there is debate between experts about whether to continue or discontinue suboxone perioperatively.
To discontinue suboxone preoperatively is challenging because of the requirement for coordination between the care teams
in the preoperative period. That is, once a surgery date has been determined, the patient would need to be converted to
pure agonist under the guidance of their prescriber. There will need to be coordination with the APS and regional teams to
determine non-opioid strategies for pain management. While in the hospital, APS in consultation with a chronic pain
specialist would manage the patient’s medications. For discharge planning there will be a re-introduction of suboxone in
conjunction with the initial prescriber. Items for consideration include 1) the highly stressful transition to regular opioids
before surgery and re-induction of suboxone after discharge from hospital; 2) the emotional stress of possible risk of
withdrawal or exacerbation of the previous chronic pain; 3) the risk of opioid use disorder relapse; 4) the need for support
from the original suboxone prescriber and chronic pain specialist perioperatively to adjust the doses of opioids; and 5) the
coordination of scheduling and/or cancellation of surgery.
At LHSC, it has been decided the preoperative strategy is to continue the use of suboxone because of the evidence that
buprenorphine is effective in treating pain, depression, and opioid-induced hyperalgesia. Providers may consider strategies
for continuing suboxone perioperatively. The analgesic duration of action for suboxone is not yet determined. However,
most studies reported divided doses for pain management. Some authors believe that the analgesic duration of suboxone
is 6-8 hours. Below is information, a protocol, and process for managing patients who present for surgery and are on
suboxone.
Suboxone is available as a fixed combination of buprenorphine and naloxone in a 4:1 ratio:
8 mg buprenorphine + 2 mg naloxone
2 mg buprenorphine + 0.5 mg naloxone
Therefore, when we say “8 mg of suboxone” then we mean 8 mg buprenorphine + 2 mg naloxone.
Minor Operations/Day Cases (Elective and Emergent Admissions)
1. Continue suboxone therapy. Be sure that the patient has taken their suboxone dose before surgery.
2. Maximize non-opioid analgesia, regional techniques and adjunctive therapy.
3. Titrate a short-acting potent opioid analgesic to effect.
Major Operations (Elective and Emergent Admissions)
1. When possible, assess the patient in preadmission clinic and reassure the patient regarding postoperative pain
management.
2. Regional analgesia – consider epidural or peripheral nerve catheter, if possible.
3. Continue suboxone therapy. Be sure that the patient takes suboxone dose before surgery.
4. Divide the suboxone to TID or QID.
5. Use preoperative pre-emptive analgesia (acetaminophen, NSAIDS, gabapentinoids)
6. Utilize intraoperative IV lidocaine/ketamine or dexmedetomidine if possible + potent opioids (hydromorphone,
sufentanil or fentanyl).
7. Maximize adjuncts postoperatively, e.g. IV lidocaine, IV ketamine, gabapentinoids.
8. Maximize non-opioid therapy postoperatively, e.g. acetaminophen, NSAIDS.
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9. Titrate postoperative potent opioid analgesia for breakthrough (oral or PCA). Start with 50% more than opioid naive
patient.
10. Assess in PACU (involve APS when possible). APS specialist or NP may contact a chronic pain physician if required.
11. If pain is uncontrolled even with sufficient potent opioids, titrate/add 25%-50% suboxone to the total daily with
max of 24 mg/day (e.g 8 mg TID or 6 mg QID). Start additional dose in PACU if the patient received suboxone > 6h
before surgery or did not receive the preoperative dose. Do not increase the other regular opioids when suboxone
has been increased because it is unlikely going to work.
12. Readjust the dose of suboxone at time of discharge to the preadmission dose.
13. Discharge the patient with 1- 2 weeks of potent PO opioids (e.g hydromorphone) with other non-opioid analgesics
(acetaminophen, NSAIDS, gabapentinoids). N.B: This protocol does not apply for Butrans patch in which the
buprenorphine dose is usually small in comparison to suboxone.
Nabilone
The only available study suggests that nabilone worsens post-op pain rather than helping. If the patient is on it at home, it
should be continued to avoid withdrawal, otherwise we don’t advise starting it.
Occasionally, people will ask if it can be used to prevent cannabis withdrawal. The studies have been done with dronabinol,
not nabilone. Theoretically, it could help, but there is no literature to support this.
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References
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2.
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Pharmacol. 2015; 31: 6-13
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