++
A pharmacist offers a unique perspective when establishing or expanding
an acute pain service using regional anesthesia/analgesia techniques.
Pharmacists have extensive training in pharmacology, pharmacokinetics, and
pharmacoeconomics. In addition to the traditional role of the pharmacist in
compounding and dispensing medications, a pharmacist can be a valued team
member who provides clinical services in the areas of safe, rationale, and
cost-effective drug therapy. Pharmacists may provide patient education and
instruction, drug information, and alternative therapy options. Pharmacists
may also be included in quality assurance data collection, proper pump
selection, proper medication labeling, safety considerations, and the
development of policies and procedures. Pharmacists can also be involved in
hospital formulary medication decisions and have an important role in
evaluating new products for formulary addition.
+++
Pharmacy Considerations with Epidural Delivery
++
When the technique of epidural and intrathecal administration was
developed, it was standard practice to administer medication as a single
bolus or multiple as-needed bolus injections. Anesthesiologists generally
prepared and administered the doses. This technique, however, may result in
periods of inadequate pain control and has been associated with a higher
frequency of adverse effects resulting from temporary peak levels of
medications creating unwanted side effects.66 Development
of protocols for initial bolus doses followed by continuous infusions with
or without patient-controlled epidural analgesia (PCEA) has revolutionized
pain management.65 Continuous infusions of epidural
opioids or local anesthetics (or both) avoid the peaks and valleys of pain
control and the need for multiple bolus injections.66–68
Studies comparing continuous infusions and intermittent bolus administration
have shown that continuous administration provides better analgesia with
lower total doses administered.67
++
Pharmacists should be involved in the procurement and preparation of the
epidural continuous infusion solutions. The preparation of epidural
infusions must follow strict aseptic techniques outlined by the new standard
of practice for compounding sterile preparations, published in Chapter 797
in the United States Pharmacopeia.69 Epidural solutions
are considered a “moderate risk level” for microbial contamination based on
the fact that the solution contains no preservatives.69
Appropriate labeling of epidural solutions and concentrations of commonly
used epidural additive drugs are detailed in Tables 79–12 and 79–13.
++
++
+++
Peripheral Nerve Blocks and Catheters
++
Peripheral anesthetic techniques have increased in popularity for the
management of acute and chronic pain conditions. Studies have shown that
patients who receive peripheral nerve blocks experience reduced
postoperative pain and analgesia requirements and report more satisfaction
with their pain management.70 These techniques involve
either bolus or intermittent doses, or continuous infusions of local
anesthetics through a catheter near or around the nerve or nerve plexus that
supplies the surgical area.71,72
++
A perineural placement of catheters for continuous local anesthetic is
growing in popularity.73–75 This technique of continuous
peripheral nerve blocks or perineural local anesthetic infusions involves
the percutaneous insertion of a catheter directly adjacent to the peripheral
nerves or plexuses supplying an affected surgical site.76
In the hospital setting, local anesthetic infusions can be prepared by the
pharmacy, and the continuous infusion be accomplished with an infusion pump.
In recent years, smaller electronic infusion pumps, syringe pumps,
elastomeric pumps, and spring–powered pumps have been designed for use in
the ambulatory setting. Because of the inherent risks of sending a patient
home with an infusion device, most published studies limit ambulatory use of
the pumps to patients expected to have moderate-to-severe postoperative pain
of a duration more than 24 h and who will have difficulty managing the pain
with oral opioids.76 In addition, special consideration
must be given to the caregiver's capability for managing the pump or the
need for home care or visiting nurses to monitor, regulate, or discontinue
the infusion.
++
An alternative to continuous regional blocks is continuous infusion of local
anesthetic directly into the wound site.77 A pump is
attached to a catheter inserted near an incision site. The pump infuses a
continuous flow of local anesthetic and may include the capability for
patient control. For wound instillation devices, the local anesthetic may be
added to the device in the sterile environment of the operating room or
added into the device by pharmacy personnel using aseptic technique.
++
With the capability of infusing local anesthetics epidurally, intrathecally,
peripherally, and topically, guidelines must be established for all
healthcare providers to be aware of the type and route of local anesthetic
administration. Unintentional administration of local anesthetic via two
different routes may increase the risk for systemic toxicity. To prevent
double administration, all local anesthetic administration should be
documented in the patient chart. If CPOE is available, all orders should be
entered into the computer. A warning screen should appear if duplicate local
anesthetic orders are entered for a patient.
++
With the evolution of multimodal therapy, anesthesiologists and surgeons
must communicate regarding all pain management therapy. In addition,
pharmacists must review medication profiles and be aware of all local
anesthetics dispensed and administered to patients. Pharmacists play a
crucial role in monitoring the overall pharmacologic management of the
patient.
++
Pharmacist involvement in the selection of infusion devices will offer
a unique perspective on the advantages and disadvantages of various pumps.
Many factors must be considered to determine the optimal device for a given
clinical situation. Infusion devices should be safe, accurate, reliable,
easy to use, and compatible with the drug delivery systems
available.68 For the management of acute pain, an external
pump is standard. Several external devices are available on the market,
including syringe pumps, peristaltic devices, and elastomeric reservoir
pumps. When selecting a pump, several factors should be considered,
including the acceptable infusion rate accuracy, PCA bolus capability, and
total local anesthetic volume required.
++
Syringe pumps are used to deliver the contents of a syringe over a given
period.68 These devices can be programmed to deliver the
contents of a syringe over several hours to several days. These pumps are
commonly used for the delivery of opioids for IVPCA. Prefilled morphine and
meperidine syringes are commercially available. Pharmacy personnel must
compound other opioids or differing concentrations of commercially available
products. Most of these devices must be locked to prevent patient
manipulation and to prevent diversion of a controlled substance.
++
Peristaltic devices deliver a drug from a flexible reservoir via
administration tubing that is mechanically squeezed.68
These pumps are traditionally used to administer intravenous fluids. Some
peristaltic devices have locked chambers to secure solutions. This would be
of benefit for opioid infusions. Peristaltic pumps can accommodate larger
volumes of solution. Flow rate capabilities range from 0.1 to 999 mL/h.
Newer pumps have more sophisticated programming, allowing for minimum and
maximum rates of any drug programmed into the device. Some programs also
calculate infusion rates based on the patient's weight and the amount of
drug to be administered per minute or hour. This new technology was
developed to help prevent potential medication errors.
++
Elastomeric reservoir pumps force fluid through a flow regulator via
elastomeric pressure of a balloon reservoir.68 Depending
on the brand, the reservoir volume varies, allowing for varying rates and
length of therapy. This technology is used for continuous delivery of local
anesthetics for continuous peripheral blocks or instillation directly into
the wound.
++
Regardless of the type of infusion pump used, the maximum reservoir volume
must be considered when establishing the use of epidural solutions or
continuous nerve infiltrations. In addition, the range of administration
rates is a critical factor in epidural delivery of
medications.68 Epidural infusion rates vary depending on
the location of the epidural catheter and the drugs administered into the
epidural space. Rates greater than 20 mL/h are generally not indicated.
Table 79–7 provides a general guideline for epidural administration rates
based on the placement of the epidural catheter.77Tables 79–12 and 79–13 provide useful information on epidural orders, labeling,
and solutions. Figure 79–5 is a sample epidural order form.
++
When choosing an infusion device, consideration should be given to devices
that allow for safe and secure administration of solutions while maximizing
the time between refills or the interval between bag, syringe, or cassette
changes. The potential for pump misidentification or confusion is
ever-present, leading to medication errors or error in route of deliver.
From a systems standpoint, rigorous policies are needed to prevent
medication errors. This may include special labeling, route-specific tubing,
and dedicated pumps for specific techniques, color-coding of labels and
tubing, and two practitioner pump set-up checks. Representatives from the
departments of biomedical engineering, nursing, anesthesiology, and pharmacy
should all be involved in pump selection.
+++
Solution Preparation, Stability, and Sterility
++
As described previously, pharmacists offer many valuable services to
all areas of patient care. In regard to regional anesthesia, the most
important contributions include accurate preparation and assurance of
sterility and stability for all solutions prepared.
++
Any drug administered into the epidural or intrathecal space must be
free of neurotoxic preservatives.67,78 Agents containing
preservatives such as methylparaben, benzyl alcohol, methylhydroxybenzoate,
propylhydroxybenzoate, phenol, and formaldehyde must be
avoided.67,78 Standard epidural preparations guidelines
call for the use of preservative-free solutions.
++
Although infection of the epidural or intrathecal space is rare, it can be
fatal. Preparation of all epidural solutions must be performed with strict
adherence to sterile aseptic technique. As of January 1, 2004, JCAHO
officially surveyed accredited organizations for compliance with the United
States Pharmacopeia (USP) general Chapter 797, Pharmaceutical
Compounding-Sterile Preparations.69 USP Chapter 797 details the procedures and requirements for compounding sterile preparations
and sets standards that are applicable to all practice settings in which
sterile preparations are compounded. Based on these guidelines, because
epidural solutions contain no preservatives, they are considered to be a
medium risk for microbial contamination. Certified pharmacy personnel using
a laminar flow hood should prepare epidural, intrathecal solutions as well
as solutions for continuous peripheral neural blockade.
++
The stability of morphine, fentanyl, hydromorphone, and fentanyl mixed with
various local anesthetics in a variety of syringes and reservoirs has been
studied.79–82 Solutions studied maintained potency for
at least 12 days. However, the risk of microbial contamination in
preservative-free solutions is problematic. Current guidelines from the
Centers for Disease Control and Prevention (CDC) recommend that
preservative-free infusion solutions be completely used or discarded within
24 h of preparation when not refrigerated.67,83,84 CDC
guidelines also recommend that preservative-free solutions be stored under
refrigeration for no more than 7 days.83 Refrigeration
must be continuous and occur immediately after mixing the solution. After
the product is dispensed for patient use, a 24-h expiration date must be
applied. USP Chapter 797 gives a medium risk level to preparations 30 h at
room temperature and 7 days under refrigeration.69
According to USP Chapter 797, if the product is not made in a laminar flow
hood, it will be considered high risk and should be used within 24
h.69 It would be prudent for institutions administering
epidural, intrathecal, and continuous peripheral local anesthetic solutions
to have the solutions prepared in accordance with USP Chapter 797.
+++
Standardization of Regional Anesthesia Continuous Solutions
++
Standardizing epidural solution volumes, medications used, and drug
concentrations are important considerations when establishing an epidural
program. Consistency in prescribing and preparing epidural, intrathecal, and
continuous peripheral local anesthetic solutions helps to reduce the
potential for medication errors and simplifies the preparation
process.85–87 Having a limited number of concentrations
for epidural solutions will prevent medication errors in prescribing,
preparing, and administering epidurals. Pharmacists should work with
anesthesiologists to determine dosing ranges for epidural drugs. Pharmacists
should be familiar with the dosing ranges and should question orders that
deviate from established guidelines. It would be beneficial to minimize the
size of the solution bag for epidurals. If the rate of an epidural is
mistakenly increased, a limited amount of epidural solution would be infused
at the incorrect rate.
++
When initially establishing standard epidural solutions, physician
preference and stability considerations should be
assessed.87 Decisions regarding standard epidural
preparations must also take into consideration safety, cost, time, narcotic
accountability, and reservoir volume of the infusion device.85–87 When possible, using whole rather than partial ampules and vials
and using available package sizes of the drugs will help to minimize
waste.87 This is beneficial in helping to keep narcotic
inventories as simple as possible. Although standard epidural solutions are
usually adequate for most patients, it should be noted that these standard
preparations might not be suitable for every patient. There may be instances
when a patient requires a specialized preparation. The patient may have an
allergy to one of the standard epidural components, or the patient may have
a history of opioid tolerance and will require higher concentrations. If a
nonstandard epidural is ordered, highlighting the concentrations may help to
prevent confusion and errors.
++
++
Standardization of epidural solutions may allow for batch preparation.
Batch preparation helps to prevent a delay in starting an epidural. In
addition, depending on the infusion rate, more than one infusion bag may be
needed per day. If an infusion is running dry, having batched solutions
available prevents the possibility of interrupting continuous pain therapy.
Batching puts less stress on pharmacy personnel preparing solutions and on
nurses in a need of a new solution bag. However, maintenance of continuous
pain relief therapy for the patient is the most important benefit. To
provide the maximum expiration dating, certified individuals should do batch
preparation of epidural solutions without preservative under strict aseptic
conditions. Storage should be in accordance with the CDC and USP Chapter 797.69
++
Some pharmaceutical manufacturers provide compounding services for
epidural and other solutions. Others manufacture standard concentrations.
Expiration dating is extended beyond 7 days based on stability studies
conducted by the pharmaceutical manufacturers. Institutions handling a large
number of surgical and obstetric cases may find this service of use because
compounding large amounts of epidurals requires additional staffing,
supplies, and time. Therefore, the cost of the compounded products should be
weighed against pharmacy considerations associated with preparing the
solutions.87
+++
Safety Considerations
++
Medication errors related to the use of opioid infusions and epidurals
are among the most frequently reported.85 To help prevent
medication errors, it is imperative that all epidural solutions be labeled
in a clear, concise, consistent manner. Table 79–12 provides suggestions
for the appropriate labeling of epidural solutions.84
Labels should be legible and permanently affixed to the infusion bag or
syringe in a manner that makes it easily readable.84 The
patient's name, date of preparation, and solution expiration should be
clearly stated. The medication contents should be distinctly labeled with
the name of the drugs and volumes used to prepare the solution. In addition,
the final concentration and total volume should be clearly marked on the bag
in bold lettering. Last, a bright auxiliary label reading “For Epidural Use Only" should be affixed
to the bag or syringe.
++
Drugs intended for intravenous administration have been accidentally
administered into the epidural or intrathecal space.67,85–86 An error in the route of administration could have catastrophic
consequences. The route of administration must be clearly noted on all order
forms. Drug concentrations vary dramatically between intravenous, continuous
peripheral block, epidural, and intrathecal routes. If an intravenous
solution of morphine 1 mg/mL is administered epidurally, respiratory
depression and death may result. In addition to anesthesiologists, nurses
and pharmacists should be familiar with dosing ranges and standard
concentrations for epidural and intrathecal preparations.
++
Proper labeling of the epidural tubing is also imperative. It is recommended
that the distal ends of epidural and intravenous lines be labeled to clearly
differentiate them.85 A line dedicated to the
administration of epidurals with port-free tubing should always be used to
prevent accidental epidural administration of drugs intended for intravenous
use.85–86 It is also helpful to use single-chamber pumps
dedicated to epidural infusions. Infusion pumps should also be labeled
“For Epidural Use Only." If a multiple-chamber pump must be used for epidural administration, the
other chambers should not be used for the infusion of any other medications.
If an adjustment in rate or another medication is administered to the
patient, nurses should always trace the tubing from the insertion site to a
pump. If more than one pump is being used, placing the IV pump on the
opposite side of the patient's bed from the epidural pump may help to
prevent mistakes.85
++
Healthcare practitioners should be aware of the potential for error with
hand-written orders. Only proper abbreviations should be accepted and
clarification of any order completed prior to processing. The use of
preprinted order forms has helped to reduce these types of errors. The ASA
Task Force on Pain Management has established guidelines for the use of
preprinted order forms in acute pain management.88 The key
elements for epidural analgesia preprinted order forms are listed in Table
79–8.
++
If a patient is receiving an epidural opioid, prescribing other sedative
agents should be done with extreme caution. The service or anesthesiologist
managing the epidural should be the only service prescribing other
sedatives. If another service prescribes another sedative, the pharmacist
should intervene and notify the service managing the opioid epidural. If
CPOE is available, a warning screen should be displayed if a sedative is
ordered.
++
++
The pharmacist's role in regional anesthesia may include reviewing
patients' drug therapy, optimizing medication selection, and developing
policies and procedures. Pharmacists also supervise and evaluate solution
preparation, stability, storage, and safety issues. Additionally, the
pharmacist can provide information on the cost of different mediation
modalities, offering suggestions for the most cost-effective choices.