CHS Patient Evaluation & Treatment Protocols 3 — Questions and Answers
Question 1: When performing a pre-dive assessment, a patient reveals they took a sulfonylurea medication this morning without eating. What risk does this present during HBO therapy?
- Increased risk of barotrauma due to gas expansion
- Hypoglycemia exacerbated by the metabolic effects of HBOT (Correct answer)
- Decreased wound healing efficacy due to insulin pathway interference
- Elevated seizure threshold requiring lower treatment pressure
Correct answer: Hypoglycemia exacerbated by the metabolic effects of HBOT
Sulfonylureas lower blood glucose, and HBOT can further affect glucose metabolism, making hypoglycemia during treatment a significant safety concern.
Question 2: A patient with chronic carbon monoxide poisoning presents 36 hours after exposure. Which statement best describes the rationale for still offering HBOT?
- HBO has no benefit beyond 6 hours post-exposure
- Delayed HBO may still reduce the risk of delayed neurological sequelae (Correct answer)
- HBO at this stage focuses on eliminating carboxyhemoglobin remaining in blood
- HBO beyond 24 hours is only indicated for pregnant patients
Correct answer: Delayed HBO may still reduce the risk of delayed neurological sequelae
Even with delayed presentation, HBOT may reduce the incidence of delayed neurological syndrome by addressing CO bound to cytochrome oxidase and lipid peroxidation.
Question 3: During evaluation for radiation tissue injury, a patient reports the irradiated tissue TcPO2 is 8 mmHg on room air but rises to 95 mmHg during an HBO challenge. How should this be interpreted?
- The tissue is unsalvageable and HBO is contraindicated
- The tissue is hypoxic but has patent vasculature — HBO is likely to be beneficial (Correct answer)
- No conclusion can be drawn without a biopsy
- The baseline is too low; the patient needs revascularization before HBO
Correct answer: The tissue is hypoxic but has patent vasculature — HBO is likely to be beneficial
A dramatic rise to 95 mmHg during the HBO challenge confirms that the vasculature can respond to increased oxygen pressure, predicting a favorable treatment outcome.
Question 4: Which of the following contraindications to HBOT is considered ABSOLUTE rather than relative?
- Chronic obstructive pulmonary disease
- Untreated pneumothorax (Correct answer)
- Claustrophobia
- Current use of bleomycin chemotherapy
Correct answer: Untreated pneumothorax
An untreated pneumothorax is the only absolute contraindication to HBOT because pressurization can convert it into a life-threatening tension pneumothorax.
Question 5: A patient receiving HBOT for osteomyelitis has a serum glucose of 380 mg/dL prior to a scheduled session. What is the correct course of action?
- Proceed with treatment as hyperglycemia is not a contraindication
- Delay treatment until glucose is below 250 mg/dL and optimize glycemic control (Correct answer)
- Cancel all future HBO sessions until diabetes is controlled
- Administer insulin inside the chamber and monitor during the dive
Correct answer: Delay treatment until glucose is below 250 mg/dL and optimize glycemic control
Severe hyperglycemia impairs leukocyte function and wound healing; delaying treatment until glucose is better controlled maximizes therapeutic benefit and patient safety.
Question 6: What is the primary purpose of air breaks during a hyperbaric oxygen treatment table?
- To allow the patient time to equalize middle ear pressure
- To prevent CNS and pulmonary oxygen toxicity by reducing cumulative oxygen exposure (Correct answer)
- To decompress the patient safely between oxygen breathing periods
- To flush carbon dioxide buildup from the chamber atmosphere
Correct answer: To prevent CNS and pulmonary oxygen toxicity by reducing cumulative oxygen exposure
Air breaks reduce the total oxygen dose and cumulative unit pulmonary toxicity dose (UPTD), protecting against both CNS seizures and pulmonary oxygen toxicity.
Question 7: A patient with necrotizing fasciitis is brought to the hyperbaric facility postoperatively. Under what condition should HBOT NOT delay operative management?
- When the patient's WBC is above 20,000
- When surgical debridement has not yet been performed (Correct answer)
- When the patient is hemodynamically unstable on vasopressors
- When gas is visible on imaging beyond the initial wound site
Correct answer: When surgical debridement has not yet been performed
HBOT is an adjunct to — never a substitute for — surgical debridement; definitive operative treatment must always take priority over scheduling a hyperbaric session.
CHS Patient Evaluation & Treatment Protocols 3
When performing a pre-dive assessment, a patient reveals they took a sulfonylurea medication this morning without eating.
What risk does this present during HBO therapy?