Chemosafety
Many
veterinarians in general practice are administering chemotherapy either
on their own or with the guidance of a veterinary oncologist.
Chemotherapy can be used in general practice provided the following:
that biosafety rules are strictly adhered to by all personnel directly
and indirectly involved with the patient and drugs, patient safety is a
priority, and that the practitioner is knowledgeable about all aspects
of the drug to be used prior to its administration.
Safety for you and your staff
Safe
handling of chemotherapy drugs cannot be overemphasized! Safety
protocols can be posted everywhere in a clinic but it is everyone’s
responsibility to understand and follow these protocols, otherwise, they
are just written words on a piece of paper. To ensure your own safety
and that of your staff, the best way to avoid unnecessary exposure to
potential toxins is by using proper handling techniques. Chemotherapy
exposure occurs three ways: aerosol, topical, and oral. To reduce or
prevent exposure the following protocols are recommended:
Prepare chemotherapy drugs in a sterile fume hood (Figure 1).
At the WCVM and other specialty clinics, this is a reasonable option
but most veterinary practices do not have hoods. Therefore, a quiet room
on a clean surface away from ventilation ducts is recommended. An
approved chemotherapy mask, gown, and gloves must be worn while
preparing chemotherapy agents. There are now commercially available
closed systems that reduce the risk of aerosolization such as PhaSeal.
At the WCVM, we have just started using this system to reduce the risk
of exposure even further. In addition, all chemotherapy is placed in a
sealed plastic bag after it is prepared to reduce contamination of
surfaces (Figure 2).
Figure 1
Chemotherapy agent drawn up in a sterile fumehood. Note that both gown and gloves are worn.
Figure 2
Once
the chemotherapy agent is prepared, the syringe is placed in a labeled
sealed plastic bag. This process prevents contamination of surfaces and
provides a disposal for all used chemotherapy waste.
Approved
chemotherapy administration gloves are preferable to latex examination
gloves that are not impermeable to chemotherapy agents. If chemotherapy
administration gloves are not available, double gloving with latex exam
gloves is acceptable. A nonabsorbent chemotherapy administration gown
or, at minimum, a clean buttoned up lab coat should be worn during
administration. A mask and protective eye-wear should also be worn. This
protective wear should be worn by both the “giver” and the “holder” (Figure 3).
Figure 3
Demonstration of chemotherapy administration — note gown, gloves, and mask.
No
food or drink should be in the chemotherapy administration room. A
refrigerator should be assigned for chemotherapy drugs only and food
should never be stored in the same place.
Once you
are finished administering the drug, all chemotherapy waste (syringe, IV
catheter, bandages, etc) should be returned to the sealed plastic bag
and disposed of with other Biohazardous Waste according to government
regulations in your area and not thrown in a sharps container or
garbage.
Because chemotherapy drugs are excreted in
feces and urine, we advise clients to wear gloves when cleaning up after
their pets for up to 48 h after drug administration and wash the area
with diluted bleach. Presently there are no written guidelines that
exist for the disposal of pet waste.
It is
recommended that pregnant or nursing staff refrain from being involved
with handling chemotherapy drugs and patient waste. If there are
inquiries as to other individuals who may be at increased risk
(immunocompromised), consider discussing the situation with a physician.
A pre-existing protocol should be in place (for example, spill-kit, emergency procedures) should a spill occur.
Safety for your patient
Regardless
of the type of drug you are using, it is essential to know how to
administer it (oral, subcutaneous, intramuscular, or intravenous) and
once it is given what general and specific side effects may occur. For
example, L-asparaginase is a safe and well tolerated drug when
administered subcutaneously or intra-muscularly. If given intravenously,
L-asparaginase will result in a (potentially fatal) anaphylactic
reaction (1).
Another important example is cyclophosphamide, an alkylating agent that
is effective against a wide range of tumors. A major side effect that
may occur even after a single dose is sterile hemorrhagic cystitis. This
side effect can greatly alter quality of life for a patient, thus, by
taking simple precautionary measures such as administering
cyclophosphamide with either prednisone or furosemide (1 mg/kg once), we
can greatly reduce this problem (1).
Since
most chemotherapeutics are administered intravenously, a well-placed
catheter is essential. If the vein has been recently used, or if you
have already damaged the vein in an attempt to place a catheter, go to a
new leg. “Fishing” for the vein cannot be done as you are potentially
putting microtears in the vessel with each “stick.” This author always
uses the jugular vein for taking blood samples and saves peripheral
veins for chemotherapy administration. Having an indwelling catheter
should prevent accidental extravasation of tissue irritants such as
vincristine, vinblastine, or doxorubicin. Be sure to flush the catheter
with 0.9% sodium chloride before and after administration of the
chemotherapy drug.
If strict adherence to IV catheter
rules occurs, extravasation can virtually be eliminated; however,
accidents can still occur. If extravasation occurs with a mild/moderate
vesicant such as vincristine or vinblastine, you should aspirate the
drug out of the site if possible. Mark the area with an indelible marker
so the affected area can be observed. Inflammation and edema can be
reduced by applying warm compresses to the site for 10 to 15 min every 6
h for 24 to 48 h. Even though the resulting tissue damage can sometimes
be significant, it rarely results in the loss of the limb.
However,
if a severe vesicant like doxorubicin is extravasated, the resulting
damage can be so severe that it may warrant amputation or even
euthanasia of the patient (Figure 4) (1).
If extravasation occurs, attempt to aspirate as much drug as possible.
Do not flush the area with saline in an attempt to dilute the drug; this
will only spread the drug further into the tissue. Place another IV
catheter in a different leg and administer dexrazoxane (Zinecard) at 10 ×
the dose of doxorubicin (if the dose of doxorubicin was 20 mg, then
administer 200 mg of Zinecard). The initial dose should be given within 3
h of extravasation and then again within 24 and 48 h. While no clinical
trial has been reported for using this protocol, anecdotal reports in
client-owned patients have shown that this approach works and has
greatly lessened the severity of tissue damage. If dexrazoxane is not
available, early surgical debridement can be done.