STANDARDS & GUIDELINES

 

 

PCA

Introduction

Patient-controlled analgesia (PCA) is a method of providing analgesia using a computerized pump that allows patients to self-administer predetermined doses of opioids. The delivery of small, frequent intravenous boluses of opioids results in reasonably constant serum concentrations of the opioid. An effective PCA program requires bedside nurses, physicians and pharmacists to monitor and titrate PCA settings based on adequacy of pain control, sedation, and other side-effects.

Indications and Contraindications

Indications:

  • Moderate to severe pain requiring opioid medication
  • Pain anticipated to last more than 10 to 12 hours
  • Patient willing to take control of their analgesia
  • Patient able to understand PCA
  • The oral route is not appropriate
  • Procedural pain

Contraindications:

  • Patient unwilling to participate in their pain management
  • Lack of staff training in PCA (nursing or physician)
  • Patient unable to understand PCA
  • Patient obtunded or sedated
  • Physical impediments to pushing the PCA button.
  • Opioids are contra indicated:
    • Increased intracranial pressure
    • Sleep apnea
    • Respiratory compromise

Choice of Agents

Three opioids are currently available for use in PCA:

  • Morphine
  • Fentanyl
  • Hydromorphone

A) Morphine

Concentration

  • 1 mg/ml (usual concentration)
  • 5 mg/ml (opioid tolerant / high opioid use patients ONLY)

Contraindications

  • Allergy to morphine - rare but needs to be differentiated from the common side effects
  • Renal dysfunction - metabolite (morphine 6 glucuronide) accumulates which can cause sedation, respiratory depression
  • Hepatic dysfunction
  • Asthma - may release histamine

Advantages

  • Inexpensive
  • Vast clinical experience

Disadvantages

  • Slow onset (10-15) minutes after an intravenous bolus injection
  • Histamine release (contraindicated in asthmatic)
  • Morphine-6-glucuronide is a metabolite that results in sedation, nausea,vomiting and respiratory depression.
  • Increased accumulation of morphine in patients with liver dysfunction
  • Opioid side effects:
    • Nausea and vomiting
    • Constipation secondary to reduced peristalsis
    • Pruritis
    • Respiratory depression

B) Fentanyl

Concentration

  • 10 mcg/ml (usual concentration)
  • 50 mcg/ml (opioid tolerant / high opioid use patients ONLY)

Contraindications

  • Allergy to fentanyl - rare but needs to be differentiated from the common side effects

Advantages

  • Rapid onset (3 to 5 minutes)
  • No active metabolites; therefore, indicated with renal or hepatic dysfunction
  • Non-sedating

Disadvantages

  • Cost - more expensive than morphine
  • Opioid side effects:
    • Nausea and vomiting
    • Constipation secondary to reduced peristalsis
    • Respiratory depression
    • Pruritis

C) Hydromorphone

Concentration

  • 0.2 mg/ml (usual concentration)
  • 1 mg/ml (opioid-tolerant/high-opioid us patients ONLY)

Advantages

  • Onset intermediate between morphine and fentanyl
  • Non-sedating

Disadvantages

  • Cost - more expensive than morphine
  • Hydromorphone-3-glucuronide may cause excitation when used in high doses particularly with impaired renal dysfunction
  • Opioid side effects:
    • Nausea and vomiting
    • Constipation secondary to reduced peristalsis
    • Respiratory depression
    • Pruritis

Meperidine (not available for PCA at Duke)

Meperidine is not available for PCA therapy. Accumulation of normeperidine, a metabolite of meperidine, can precipitate seizures. Seizures have occurred after less than twenty-four hours of meperidine with less than 400mg

Dosing

The following components of PCA should be calculated and indicated on PCA order forms:

• Loading dose

• Lockout interval

• Maintenance dose

• Four-hour limit


Continuous infusion and dosing adjustments may also be included on the order form, if needed.

Agent Summary

All opioids infusions are prepared in approximately equipotent doses:

Morphine 1 mg/ml = Fentanyl 10 mcg/ml = Hydromorphone 0.2 mg/ml.

 

Loading Dose

The loading dose accelerates attainment of an effective blood level of the opioid at the initiation of therapy or for procedures. Since there is marked inter-patient variability in the amount of analgesic required for pain relief, the loading dose must be titrated to effect. Many studies have demonstrated a five fold variability in the quantity of intravenous opioid required to produce equivalent analgesia after surgery. The loading dose should be repeated every 5 -10 minutes (5 minutes for fentanyl) so that the effect of the dose is felt before the next dose is administered. The size of the initial loading dose is influenced by:

  • Weight ( lean body weight)
  • Age (>65 years dose decreased by 25%)
  • Physical status ( dose decreased by 25 -50 % in debilitated patients)
  • Opioid tolerance (Increase the dose 25-50%)

If the initial 3 to 4 loading doses are ineffective the loading dose can be increased by 25 to 50 % after an appropriate assessment of the patient. The increased loading dose can be repeated as many times as required, titrated against the patient's pain level and the side effects of the opioid. Patient weight is a useful guide in initiating PCA dosing, even though the correlation between analgesic requirement and weight is poor. The volume of distribution of the opioids in the plasma is weight related resulting in an appropriate blood level of the opioid.

Loading Dosing Examples:

Average Patient (54 year male - 70 kg)

Morphine

Fentanyl

Hydromorphone

0.04mg/kg X 70 kg = 2.8 mg

0.5 mcg/kg x 70 kg = 35 mcg

0.01mg/kg x 70 kg = 0.7 mg

 

Elderly Patient (75 year female - 50 kg [ 0.75 age reduction])

Morphine

Fentanyl

Hydromorphone

0.04mg/kg X 50kg x 0.75 = 1.5 mg

0.5mcg/kg x 50kg x 0.75= 19 mcg

0.01mg/kg x 50 kg x 0.75 = 0.3 mg

 

Opioid tolerant Patient (40 year female - 70 kg[1.25 increase])

Morphine

Fentanyl

Hydromorphone

0.04mg/kg x 70kg x 1.25 = 3.5 mg

0.5mcg/kg x 70kg x 1.25= 44 mcg

0.01 mg/kg x 70 kg x 1.25= 0.9 mg

 

PCA (Maintenance) Dose

The PCA dose of opioid is the amount of drug the PCA pump will deliver when the demand button is pressed. The size of the maintenance (PCA) dose is the primary determinant of the effectiveness of PCA. Therefore, titration of the maintenance (PCA) dose, based on objective caregiver assessment of pain, is the cornerstone of PCA therapy.

If the PCA dose is set too low the majority of the patient's will be frustrated with having to press the button frequently. Alternatively a too large a dose will result in dose related side effects.

Patient weight is a useful on which to base the PCA dose, even though the correlation between analgesic requirement and weight is poor. The volume of distribution of a drug is often weight-related and thus a useful guide to prevent over-or under-dosing. (Dosing for elderly [>65 year old.] or debilitated patients should be decreased by 25 percent.)

Improved levels of analgesia and patient satisfaction are achieved when repeated demands are minimized; therefore, caregivers should attempt to keep the average number of demands to approximately two per hour. (See the PCA Management Algorithm on the inside back cover.)

Maintenance Dosing Examples:

Average Patient (54 year male - 70 kg)

Morphine

Fentanyl

Hydromorphone

0.02mg/kg x 70 kg = 1.4 mg

0.3 mcg/kg x 70 kg = 21 mcg

0.005 mg/kg x 70 kg = 0.3 mg

 

Elderly Patient (75 year female - 50 kg [ 0.75 age reduction])

Morphine

Fentanyl

Hydromorphone

0.02mg/kg x 50kg x 0.75 =0.8 mg

0.3mcg/kg x 50kg x 0.75= 23 mcg

0.004 mg/kg x 50 kg x 0.75= 0.15 mg

 

Opioid tolerant Patient (40 year female - 70 kg[1.25 increase])

Morphine

Fentanyl

Hydromorphone

0.02 mg/kg x 70 kg x 1.25= 1.8 mg

0.3 mcg/kg x 70 kg x 1.25= 26 mcg

0.005mg/kg x 70 kg x 1.25= 0.4 mg

 

Lockout Interval

The lockout interval is the period during which the PCA unit is refractory to further demands by the patient. The lockout interval (LOI) is a necessary safeguard to prevent patients from taking an additional dose before appreciating the effect of the preceding dose. The refractory period limits the potential of the patient administering an inadvertent overdose due to the "stacking" of opioid doses. Therefore, the speed of agent onset should be accounted for when determining the lockout interval. Long lockout reduces the patient's ability to obtain an effective analgesic level if they fall behind, i.e. following sleep.

Lockout Intervals Examples:

          Morphine…………………………… 8 minutes
          Fentanyl…………………………… 6 minutes
          Hydromorphone…………………… 8 minutes

Four-hour Limit (Abbot PCA Pumps)

This safety feature prevents a patient from receiving more than a pre-determined amount of opioid within a four-hour period. This period of time is a "moving window" that accounts for drug intake during the four hours preceding any given moment. Given large inter-patient variations, it is not feasible to predict an appropriate four-hour limit. The four hour limit is a safety feature to call attention to the amount of opioid required. The four limit is not a punitive feature but a call for further assessment.

If a patient reaches the four-hour limit, the site, intensity, and nature of the pain must be assessed before the four-hour limit is discontinued. Failure to realize that the patient has reached the four-hour limit is one of the most common causes of inadequate analgesia. If the four hour limit has been reached and the patient is in pain the four limit should be increased and appropriate loading dose / doses should be given. Standard four hour limits are inadequate in the opioid tolerant patient. In order to ensure adequate analgesia in the opioid tolerant patients or those patients who use more analgesia a more concentrated opioid solution should be used allowing higher four hour limits to be selected.

Common Four-hour Limits Examples:

The four-hour limit ranges from 0 to 30 mls of the opioid solution selected. The default limit four-hour limit is 30 mls of the solution, so the concentration of the selected agent will determine the mcg or mg amount of opioid. Although no four hour limit can be selected it is advisable to have a warning of high opioid use ensure repeated patient assessment.

Agent

Concentration

Four-hour Limit

Morphine

1 mg/ml

0.3 mg/kg or up to max 30 mg

5 mg/ml

up to max 150 mg

 

Fentanyl

10 mcg/ml

3 mcg/kg or up to max 300 mcg

50 mcg/ml

up to max 1500 mcg

 

Hydromorphone

0.2 mg/ml

60 mcg/kg or up to max 6 mg

1 mg/ml

up to max 30 mg

 

Continuous Infusion

The addition of a continuous infusion may be necessary in opioid-tolerant patients or patients with high utilization of PCA over an extended period of time (>12 hours). In the average patient, continuous infusion results in a higher incidence of side effect with minimal improvement in pain relief.

Ideally the rate of a continuous infusion should be based on average hourly usage of PCA over an extended period of time (>12 hours). For acute pain, which is subject to rapid change, the continuous infusion rate should be approximately one-third of the average hourly usage. For chronic pain (e.g. cancer, mucositis), up to two-thirds of the average hourly usage is appropriate.

Continuous Infusion Examples:

Patient utilizes 72 mg morphine over the preceding 12 hours
Average hourly usage = 6 mg (72 mg ÷ 12 hours)

 

Acute Pain ( Extreme Caution)

Chronic Pain ( Opioid tolerant )

Continuous Infusion

2 mg /hour

4 mg /hour

PCA

2 mg

2 mg

Lockout Interval

8 minutes

8 minutes

4 Hour Maximum

30 mg

0 or 45 mg (if 5 mg/kg morphine is used)

 

Titration

Titration of maintenance (PCA) dose is based on pain and sedation scores. With the use of opioids, complete eradication of pain is often unattainable without an unacceptable incidence of serious side effects. Pain scores of <= 3 at rest and <= 5 out of 10 with activity (e.g., deep breathing, coughing, movement) are reasonable goals for PCA. A Ramsay score of > 4 indicates excessive sedation and should prompt downward adjustment of dose. (See the PCA Management Algorithm on the inside back cover.)

With inadequate analgesia the initial step should be an appropriate loading dose followed by an increase in the size of the PCA dose. The recommended increase in dose size should be approximately 25%. This will ensure that the patient feels the effect of the increased dose and trust will be established. Opioids are not effective in the management of anxiety or spasms. Appropriate pharmacological and non-pharmacological therapy should be selected to treat the problems of anxiety and muscle spasms.

Monitoring

All patients receiving intravenous PCA should be monitored at least every four hours, unless there is a medical reason dictating more frequent monitoring. Results of the following parameters should be recorded on a flow sheet at the patient's door:

  • Pain
  • Sedation
  • Respiratory rate
  • Vital signs
  • Amount of opioid used

Pain

By definition, pain is "what the patient reports." Pain should be assessed regularly using a tool appropriate to a patient's age and cognitive ability. In cases involving young or non-cognizant patients, family members and/or nurses can assist with assessment. It is imperative to also determine the site(s) of pain and to assess their characteristics (e.g. burning, aching, cramping) to differentiate causes of pain. (For example, an assessment could distinguish abdominal pain from coronary ischemia.)

A comprehensive pain history should include:

W

- Word to describe the pain (shooting, stabbing , throbbing etc)

I

- Intensity ( see age appropriate scales below)

L

- Location ( there are often many sources of pain and each needs to be assessed)

D

- Duration of pain

A

- Aggravating or alleviating factors

 

 

Pain Intensity - Adults

Verbal Rating Scale (VRS)

cognizant adults ( Usually zero to 10)

Pain Thermometer

elderly patients

Faces Scale

non-cognizant adults

 

Pain Intensity - Pediatrics

Verbal Rating Scale

older verbal children

Faces Scale

younger children (3-9 years)

Objective Pain-Discomfort Scale (OPS)

younger children (1-7 years) and nonverbal children

 

(See the PCA Management Algorithm on the inside back cover.)

 

Sedation

Along with the pain score, sedation must be assessed every four hours, using the modified Ramsay Scale (see box). Assessment of sedation is an integral component of a comprehensive exam, as sedation may be caused by hypercapnia and is often associated with hypoxia. Determination of hypoxia or hypercapnia should lead to a reduction in dose and/or discontinuation of PCA.

Modified Ramsay Scale for Sedation Monitoring:

  1. Patient anxious agitated, or restless.
  2. Patient cooperative, oriented, and tranquil.
  3. Patient responds to vocal commands.
  4. Patient asleep. Responds to gentle shaking or loud auditory stimulus.
  5. Patient asleep. Does not respond to gentle shaking or loud auditory stimulus; does respond to pain.
  6. Patient unarousable. Does not respond to pain or noxious stimuli.

Respiratory Rate

Although opioid overdose can cause reduction in respiratory rate, the more characteristic change is a decrease in tidal volume. Decrease in tidal volume causes hypercapnia with resulting sedation.

Vital Signs

All patients receiving PCA should have regular monitoring of vital signs every four hours.

Amount of Opioid Used

Total amount of opioid used should be noted every four hours, as well as the amount used during the previous four-hour period.

Side Effects

In addition to pain, sedation, respiratory rate, vital signs, and amount of narcotic used, caregivers must also assess patients for side effects related to opioid therapy. A problem-oriented physical examination should be performed at suitable intervals to check for the following problems:

  • Excessive sedation and respiratory depression
  • Nausea and vomiting
  • Pruritus

(See Management of Side Effects on page #.)

Adjuvant Therapy

Additional agents should be used in addition to optimization of the PCA dose.

Non-Steroidal Anti-Inflammatory Agents

Nonsteroidal anti-inflammatory agents should be used whenever safe and appropriate to supplement the opioids.

All NSAIDS are contra indicated in patients with aspirin allergy and impaired renal function.

Ketorolac is the only NSAID currently available for parenteral use. Ketorolac, is a cyclooxygenase 1 inhibitor limiting its use in patients with impaired renal function, bleeding disorders, or a history of peptic ulcers.

Ketorolac use should be limited to 48 hours of therapy, with an in-depth assessment of the patient before re-ordering the drug. The package insert limits the parenteral dosing to less than 5 days. The routine use of intramuscular ketorolac, as with any other intramuscular analgesics is not recommended. The dose of ketorolac is:

          30 mg Q 6 hourly if > 50 kg and < 65 years
          15 mg Q 6 hourly if < 50 kg and or > 65 years

  • Ibuprofen is extremely useful but is only available in an oral formulation. The maximal total daily dose of ibuprofen is to 2.4 - 3.2 grams per day.
  • The COX2 NSAID agents are as effective as the older COX1 NSAIDS as anti-inflammatory agents and analgesics but have no effect on coagulation or the gastro intestinal tract. The dose of the COX 2 agents for acute pain are:
    • Celebrex 200 - 400 mg q 12 h PO (usually start with the lower dose)
    • Vioxx 50 mg q day for 5 days and then reduce to 25 mg q day

The COX 2 agents are indicated in the elderly, those on corticosteroids or anticoagulants, patients with peptic ulcer disease or risk of post operative bleeding.

Antispasmodics

Antispasmodics, including methocarbamol, diazepam, and cyclobenzaprine, should be selected as appropriate for the situation.

Anxiolytics

Anxiolytics should be used in appropriate doses realizing the synergistic effect with the opioids already being utilized by the PCA patient.

Appropriate Anxiolytic Doses

Ativan

0.25 - 0.5 mg IV q6hprn

Diazepam

2.5 - 5 mg IV q6hprn

 

MANAGEMENT OF INADEQUATE ANALGESIA

Initial Maintenance (PCA) Dose Adjustments

The first consideration in a case of inadequate analgesia (pain >5) should always be the potential of additional pathology causing the pain. Pain rated as > 7/10 must be considered as a medical emergency and get appropriate immediate therapy.

If a patient is reporting pain >5 and has received <2 doses in the preceding hour, a the patient should be encouraged to increase usage of the PCA device and then reassess within one hour. If a patient has received >3 doses in the preceding hour the maintenance (PCA) dose should be increased by at least 25 percent and an appropriate loading dose should be added, if necessary. The patient should then be reassessed within one hour. If analgesia continues to be inadequate, further therapy is indicated. (See the PCA Management Algorithm on the inside back cover.)

Upon assessment of the patient, the following should be considered:

  • Administer loading dose (page #)
  • Discontinue four-hour limit (page #)
  • Increase maintenance (PCA) dose (below#)
  • Administer adjuvant therapy (page #)
  • Consult Pain Service

Additional Maintenance (PCA) Dose Adjustments

If a patient continues to report a pain score >5 for one hour, the physician may make additional adjustments to the maintenance (PCA) dose. To increase the dose, calculate the average hourly usage over an extended period of time (>12 hours) and divide the hourly use by two to get an approximate maintenance (PCA) dose.

Sedation and Respiratory Depression

When there is concern about a patient's sedation and/or respiratory rate, the first course of action should be to administer oxygen, followed by addition or adjustment of drug.

  • If sedation score <4 and respiratory rate >8,
    Administer oxygen and halve the size of the maintenance (PCA) dose.
  • If sedation score <4 and respiratory rate <8,
    Administer oxygen, order naloxone 100 mcg IV, and reduce maintenance (PCA) dose.
  • If sedation score >4, regardless of respiratory rate,
    Administer oxygen and order naloxone 100mcg IV.

Nausea and Vomiting

The following treatment options are suggested for nausea and vomiting and should be implemented in the following order.

  • Promethazine - This agent causes sedation and could interfere with the patient's ability to participate with activity. In addition it may decrease the analgesic efficacy of the opioid and can lower the seizure threshold.
  • Prochlorperazine 5-10 mg po/iv q 6 h prn -not recommended in pediatric populations
  • Droperidol 0.625 mg IV q 6 h prn -associated with higher incidence of post operative hallucinations
  • Metoclopromide- Improves gastric motility but may provide effective anti-emetic.
  • Reduce dose of opioid
  • Change opioid
  • Opioid antagonist
    • Naloxone (Narcan) 0.25 mcg/kg/hour as a continuous infusion.
    • Nalmefene (Revex) 0.5 mcg/kg q 6 hourly as a slow IV infusion over 30 minutes.
  • 5 HT3 antagonist
    • Ondansetron 4 mg IVq 6 hourly
  • Trans Derm Scopolamine Patch applied q 72h - Indicated with nausea and vomiting associated with movement.

Pruritus

The following treatment options are suggested for pruritus and should be implemented in the following order.

  • Look for cause (strong soap on sheets, antibiotics, etc.)
  • Change opioid
  • Opioid antagonist
    • Naloxone (Narcan) 0.25 mcg/kg/hour as a continuous infusion.
    • Nalmefene (Revex) 0.5 mcg/kg q 6 hourly as an IV infusion over 30 minutes.
  • Diphenhydramine (watch for excessive sedation)

Weaning or Discontinuing Therapy

It is optimal to wean from intravenous PCA therapy to oral analgesia. In order to accomplish this:

  • Gastrointestinal tract must be able to absorb the analgesic
  • Pain must be predictable and controlled
  • Around the clock medication should include both opioids and NSAID's.
  • Start the oral regimen prior to removal of the PCA to allow for a smooth transition
  • Select the oral analgesics that provide equivalent analgesia to the intravenous PCA medication.
    • Combination analgesics are limited by the toxic levels of either the acetaminophen or ibuprofen. The maximum dose of acetaminophen that is recommended is 4 grams per day for 10 days to avoid liver toxicity. Chronic use of acetaminophen containing analgesics are linked with nephrotoxicity. This will limit the use of:
      • Hydrocodone products - low acetaminophen containing products are best
      • Codeine with acetaminophen
      • Propoxyphene with acetaminophen
  • Opioids that have no ceiling effect:
    • Morphine 1mg of intravenous morphine is equivalent to 3 mg of oral morphine. Morphine is poorly absorbed from the gastrointestinal tract, limiting its usefulness in the acute setting
    • Hydromorphone - only available as an immediate release medication limiting its usefulness as it requires frequent dosing
    • Methadone - takes a long time to reach final concentration ( 4 -12 days)
    • Oxycodone - Oxycodone is well absorbed orally without any toxic metabolites and a lower incidence of side effects. It has been found that 1 mg oxycodone PO is approximately equal to 1 mg IV morphine via a PCA device. The ideal oxycodone preparation should not contain acetaminophen or aspirin as these agents will limit the adequate dosing of the opioid. An approximate guide is presented below using a combination of a sustained release and immediate release oxycodone.

IV Morphine
24 Hour Use

IV Hydromorphone
24 Hour Use

IV Fentanyl
24 Hour Use

Sutained Release Oxycodone Oxycontin

Immediate Release Oxycodone

< 20 mg

4 mg

200 mcg

0

5 mg Q 3- 4h

30 mg

6 mg

300 mcg

10 mg Q12

5 - 10 mg Q 3- 4h

40 mg

8 mg

400 mcg

20 mg Q12

5 - 10 mg Q 3- 4h

50 mg

10 mg

500 mcg

20 mg Q 12

5 - 10 mg Q 3- 4h

60 mg

12 mg

600 mcg

30 mg Q12

5 - 10 mg Q 3- 4h

70 mg

14 mg

700 mcg

30 mg Q12

10 - 15 mg Q 3- 4h

80 mg

16 mg

800 mcg

40 mg Q12

10 - 15 mg Q 3- 4h

 

This formula allows for the easy conversion of IV morphine to oral oxycodone. Oxycontin is available as 10,20, 40 and 80 mg tablets. Since the level of postoperative pain normally decreases over time a gradual weaning is imperative based on the patients use. In the opioid naïve only prescribe the 10mg Oxycontin tablets as it allows for a gradual titration downwards. If the patient uses 2 or less doses of breakthrough medication in a 12 hour period the Oxycontin dose should be reduced by 10 mg.

 

Summary

The success of the PCA Program depends on close, continuous collaboration among nurse, physician, and pharmacist. The Doctor's Order Sheet is meant to provide a standardized approach to point-of-service PCA. The order set, combined with a standardized institutional approach to assessment of pain and sedation, will result in improved patient outcomes and satisfaction.

Because difficult patients and complicated clinical situations may not be adequately addressed with a standard protocol, consultation with the Duke Pain Service is available via formal consult whenever deemed appropriate by caregivers.

 

PCA quick reference guide

CHOICE OF AGENT

Morphine
(FIRST CHOICE)
Contraindications

  • Allergy
  • Asthma
  • Renal dysfunction
  • Hepatic dysfunction

Fentanyl
(SECOND CHOICE)
Contraindications

  • Allergy

Hydromorphone(Dilaudid)
(THIRD CHOICE)
Contraindications

  • Allergy

LOADING DOSE

0.04 mg/kg lean body weight
EX: 70kg x 0.04mg/kg =2.8 mg

0.4 mcg/kg lean body weight
EX: 70kg x 0.4 mcg/kg=28mcg

8 mcg/kg lean body weight
EX: 70kg x 8 mcg/kg =560 mcg =0.5mg

May repeat q 10 minutes x 3 doses if:
respiratory rate > 12 and
pain scale > 5 out of 10
In elderly (≥65yr) or debilitated patients, decrease dose by 25%

MAINTENANCE (PCA) DOSE

0.02 mg/kg lean body weight
EX: 50kg x 0.02mg/kg =1 mg
If c/o pain may increase by 25%
EX: 1 mg x 1.25= 1.25 (1.3) mg

0.2 mcg/kg lean body weight
EX: 50kg x0.2 mcg/kg=10mcg

If c/o pain may increase by 25%;
EX: 10 mcg x 1.25 =12.5(13)mcg

4 mcg/kg lean body weight
EX: 50kg x 4 mcg/kg =200 mcg =0.2mg

LOCKOUT INTERVAL

8 minutes standard

6 minutes standard

8 minutes standard

FOUR-HOUR LIMIT

0.3 mg/kg lean body weight
EX: 80kg x 0.3 mg/kg =24mg

3mcg/kg lean body weight
EX: 80kg x 3mcg/kg=240mcg

60mcg/kg lean body weight
EX 80kg x 60 mcg/kg =4800 mcg
=4.8 mg

If limit is reached, check pain for site, intensity, and natur to ascertain
appropriateness to pathology; if appropriate, adjust or remove limit

CONTINUOUS INFUSION

May be necessary in opioid-tolerant patients or patients with high
utilization of PCA over an extended period of time (> 12 hours).

Acute pain; 1/3 of the hourly use

Chronic pain: 2/3 of hourly use

ADDITIONAL MAINTENANCE (PCA) DOSE ADJUSTMENTS

Calculate the average hourly usage over an extended period of time (>12 hours) and divide amount
by 2 to approximate the new dose.

EX: PCA morphine dose 1mg; 36mg in 12 hr; (3mg/hr /2 = new 1.5mg PCA dose)

pain.mc.duke.edu

 

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