HBOT Safety/Review Questions #5
You are treating an epileptic canine with multiple shearing wounds with adjuvant HBOT. Which of the following is NOT a potential strategy to reduce the chance of a seizure during a treatment session?
Give IV Madazolam 10 minutes prior to each HBOT session.
Vigorously exercise the patient immediately before each treatment session to raise the body temperature.
Reduce the treatment pressure from 2.0 to 1.5 ATA.
Temporarily raise oral maintenance anticonvulsant dosage.
Time the sessions to occur at the peak blood levels after oral maintenance anticonvulsant administration.
ANSWER: 2. Vigorously exercise the patient immediately before each treatment session to raise the body temperature.
Physical exercise lowers the threshold for CNS oxygen toxicity, and exercise to the point of hyperthermia increases the uptake of oxygen by body tissues. (Reference Jain, KK, Textbook of Hyperbaric Medicine, Fifth and Revised Edition, Hogrefe, pages 52-3). Thus, excessive exercise immediately prior to HBOT is not recommended. The other strategies may all reduce the potential for seizures associated with oxygen toxicity.
You are treating cardiomyopathy and a saddle thrombus in a feline patient with adjuvant HBOT.
This cat has an intravenous catheter in place, and has been notorious for removing previous catheters during this hospitalization. You have covered the IV catheter with 100% cotton gauze, but you want to provide the added protection of a hard plastic E collar to protect the integrity of the current catheter. How can you reduce the potential for static formation associated with this plastic E collar?
ANSWER: You should protect all E collars by covering them with 100% cotton stockinette, and use only 100% cotton gauze to secure the collars around the patient's neck (pictured above). This reduces the chance of static generation by plastic or polyester fabric rubbing against the patient, chamber, or treatment module. The simple rule of thumb is: "Only the patient's body and 100% cotton should be allowed in the chamber. Anything on (or attached to) the patient which is not composed of 100% cotton should be covered by 100% cotton roll gauze, roll bandage, or stockinette". 100% cotton is the fabric with the lowest potential for generation of static electricity (Reference, Larson-Lohr V, Norvell, HC, "Hyperbaric Nursing", 2002, Best, page 137).
Select the FALSE statement describing HBOT's therapeutic effects:
HBOT can reduce intracranial pressure in head trauma.
HBOT's vasoconstrictive action can reduce tissue fluid loss in severe thermal burns.
HBOT's method of action in CO toxicity is to increase the half-life of CO from minutes to hours.
HBOT's stimulation of angiogenesis is a key factor in treatment of radiation-induced delayed wound healing.
ANSWER: 3. HBOT's method of action in CO toxicity is to increase the half-life of CO from minutes to hours.
One method of action in CO toxicity is actually the opposite. HBOT causes a reduction of CO half-life from hours to minutes, resulting in a more rapid dissociation of CO from hemoglobin. In addition, HBOT will accelerate the dissociation of CO from cytochrome oxidase in the mitochondria, and inhibit B2 integrin function for more than 12 hours after a 45 minute treatment session. The latter effect inhibits the cascade of vascular injury triggered by CO exposure, and helps ameliorate subsequent brain injury. These actions of HBOT in CO poisoning are discussed in detail with further references in Chapter 20 of the textbook, "Hyperbaric Medical Practice", Kindwall and Whelan (editors), Second Edition, Revised, Best Publishing, 2004.
You are administering adjuvant HBOT to a patient with a non- healing wound associated with previous surgery, chemotherapy, and radiation therapy.
The patient treated in the chamber just prior to this one had diagnoses of severe pancreatitis and ketoacidotic diabetes mellitus, and was on an IV infusion during the session with the line "passed through" the chamber door at an accession port.
As you start the session on the wound patient a steady hissing sound of air flowing through the accession port begins and intensifies.
What is the likely cause?
Is this an emergency?
What actions should you take?
ANSWER: The hissing sound [which will begin nearly immediately during the session] in this case is most likely due to the failure to replace the rubber "o- ring" on the accession port metal "blank". The pictures below show the placement of the "o-ring" around the metal IV "pass through port " (1) and then the location with proper placement around the "blank" (2, 3).
Other common reasons for the hissing sound are oxygen escaping from an incompletely sealed door, a door with something protruding through the seal (such as the corner of a towel), or damage to the "pass through port" or door seal "o-rings".
None of these issues are an emergency, and since all will occur at the beginning of a session, the session may be ended with a normal, gradual decompression, the "o-ring" placed in the proper position (or replaced), and then the session started again.