Chapter 29 Patient-Controlled Analgesia Flashcards
KEY POINTS 1. Patient-controlled analgesia is a programmable delivery system by which patients self-administer predetermined doses of analgesic medication at the push of a button. PCA can optimize drug delivery and improve satisfaction by enabling patients to titrate analgesia. 2. Safe use of PCA requires the patient to control analgesic delivery. Increasing plasma concentrations of opioid usually cause sedation prior to causing clinically significant respiratory depression. Sedation usually
basic variables of PCA
initial loading dose, demand (bolus) dose, lockout interval,
basal continuous infusions, and 1- to 4-hr
maximal dose limits
demand dose
the amount of
analgesic the patient receives after activation of the pump
Optimization of efficacy and safety depends on
the selection of a demand dose large enough to provide sufficient analgesia but small enough to minimize side effects
lockout interval
the time during which there will be no
drug delivery, even if the patient pushes the demand button
use of a lockout interval that is less than
the time to peak effect of the drug may result in
inadvertent overdosage due to stacking of analgesic doses. However,
lockout intervals between 5 and 10 min appear optimal regardless of the opioid used
Reasons Patient-controlled analgesia is extremely popular
Patients like the security of knowing they can
achieve pain relief quickly and easily without involving a nurse, not having to wait for pain relief, and not having intramuscular (IM) or subcutaneous injections . Because of the ease with which each demand dose can be given, small boluses can be given frequently.
PCA may avoid subtherapeutic opioid concentration troughs, which can be
associated with
unpleasant recovery secondary to guarding,
poor chest expansion, and reluctance to mobilize
PCA may also help avoid excessive peak plasma concentrations,
with associated
respiratory depression and sedation
What makes a patient is a good candidate for PCA?
patients must be
cooperative, must comprehend the concept, and must be able to push the PCA button
PCA may not be appropriate for
very young children, or for patients with certain menta or physical limitations
Nurse-controlled analgesia (NCA)
may be used if the patient’s age, developmental level, or
muscle strength interact with the ability to use the PCA device. NCA is a safe and effective method of analgesic
administration in the pediatric intensive care unit (ICU) setting.
most frequent negative perceptions relate to PCA
inadequate analgesia and/or presence of side effects, but some patients also report not trusting the PCA pump, or
fearing overdose or addiction
Oversedation with PCA can occur as a result of
repeated excessive use (patient misunderstanding of the analgesic goal), mistaking the PCA handset for the nurse call button, and family, visitor, or unauthorized nurse-activated demand
boluses
Operator errors can cause oversedation
via
programming of incorrect bolus dose size, incorrect concentrations, incorrect background infusions, and/or unintended background infusions
first choice for IV PCA
Opioids that are pure m-receptor agonists
ideal opioid for IV PCA
would have a rapid onset of action, high efficacy, and intermediate
duration of action without significant accumulation
of drug or metabolites over time
opioid-based IV PCA types
Morphine, hydromorphone,
and fentanyl
why is meperidine may not be a good first choice for IV PCA?
meperidine metabolites can accumulate
Drug/ Bolus (mg) / Lockout Interval (min)
Fentanyl: 0.015–0.05/ 3–10 min Hydromorphone: 0.1–0.5/ 5–15 min Meperidine: 5–15/ 5–15 min Morphine: 0.5–3/ 5–20 min Oxymorphone: 0.2–0.8 /5–15 min Remifentanil (labor) 0.5mcg/kg/ 2 min Sufentanil 0.003-0.015/ 3–10 min
Continuous infusions of PCA pose increased risk for
respiratory depression
Benefit of Continuous
opioid infusion in association with PCA
may provide a
more constant plasma opioid levels and improve analgesia.
ketamine
(an N-methyl-d-aspartate [NMDA] receptor antagonist) to IV PCA solutions may improve analgesian in some
Clonidine
an a2-adrenergic agonist with analgesic
properties. Addition of clonidine to morphine PCA significantly
reduced nausea and vomiting
two common alternative
routes of NONINTRAVENOUS PCAs
patient-controlled epidural analgesia and
patient-controlled peripheral nerve catheter analgesia
PCEA compared
with IV PCA.
providing better
pain control, epidural analgesia also has the potential benefits
of decreased morbidity such as fewer cardiopulmonary
complications, less thromboembolism, better mental status, earlier restoration of gastrointestinal function, enhanced functional exercise capacity and health-related quality of
life, and earlier discharge from the hospital.
potential risks associated with the placement of a catheter
epidural
hematoma, infection, or neurologic injury
Epidural analgesia with a local anesthetic combined with an opioid provides better
postoperative analgesia
than epidural or systemic opioids alone, and may improve postoperative outcome
Use of local anesthetic alone may result in
excessive motor blockade
complications of PCEA
hypotension and motor blockade.
PCEA with clonidine plus local anesthetic can provide
adequate analgesia without the usual opioid-related side effects such as nausea or pruritus
to reduce side effects and facilitate transition
to oral analgesia
the PCEA settings can be reduced gradually
rather than abruptly terminating the PCEA. This can be done, for example, by eliminating the basal rate 6 hr prior to stopping the PCEA
Many common nerve blocks for extended postoperative analgesia.
brachial plexus, sciatic, and femoral nerve blocks are amenable to having peripheral nerve catheters inserted
compared to bupivacaine, Ropivacaine may be associated with reduction
of
complete motor and sensory block,
Peripheral nerve catheter patient-controlled analgesia (PNC PCA) Common concentrations of local anesthetic
ropivacaine, 0.2% to 0.3%, and
bupivacaine, 0.12% to 0.25%.
During Labor, IV PCA (compared to intermittent IM dosing)
may provide better pain relief and reduce maternal sedation,
respiratory depression, and nausea. it reduces umbilical cord blood opioid levels (indicating less placental drug
transfer); in most cases IV PCA does not cause significant
fetal depression
PAIN CONTROL IN PEDIATRIC PATIENTS
children younger
than 4 years of age are not good candidates for PCA use. Children aged 4 to 6 years can use PCA pumps with the
encouragement of nursing staff and parents. Nonetheless, the success rate in this age-group is low. Children older
than 7 years of age often can use PCA independently
Pediatric PCA Dosing
Drug/ Bolus (mg/kg) Lockout (min)
Morphine: 10–20 /7–15 min
Hydromorphone: 5–15/ 15 min
Fentanyl: 0.1–0.2/ 7–15 min
Pediatric PCEA Dosing
Drug: Bupivacaine 0.06% + hydromorphone 10 mcg/ml Basal Rate (ml/hr): 0.1–0.3 ml/kg/hr Demand Dose: 0.1 mg/kg Lockout (min): Minimum of 10 min One-Hour Limit (ml): Max 5 0.4 ml/kg/hr
Pediatric Peripheral Nerve Catheter PCA Dosing
Drug: Ropivacaine 0.2%
Basal Rate (ml/hr) :0.1–0.2 ml/kg/hr
One-Hour Limit (ml): 0.2 ml/kg/hr
