Approved Indications

Question 0

HBO is considered adjunctive therapy for which indications?

Answer 0

Clostridial mycositis or myonecrosis

Crush injury, compartment syndrome, other acute traumatic perfusion injuries

Enhancement of healing in selected problem wounds

Intracranial abscess, actinomycosis

Necrotizing soft tissue infections

Refractory osteomyelitis

Delayed radiation injury

Compromised skin grafts and flaps

Thermal burns

Acute idiopathic sensorineural hearing loss

Question 1

HBO is considered primary treatment for what indications?

Answer 1

Decompression sickness, air or gas embolism, carbon monoxide or cyanide poisoning, exceptional blood loss anemia

Question 2

Def of DCS and causes

Answer 2

Formation of bubbles in tissues or blood upon reduction of environmental pressure.

Caused by reduction of environmental pressure. Inadequate decompression following exposure to increased pressure while breathing air

Question 3

Manifestations and first aid for DCS

Answer 3

Sx depend on where bubbles form.

Type 1-pain only-skin and constitutional symptoms

Type 2 -serious, delayed , neurological Sx

Type 3 - DCS with AGE or VGE - pulmonary Sx “the chokes”

First aid
100% oxygen
IV fluids
Return to1 ATA if Sx occurred at altitude

Question 4

Treraputic mechanisms and tx protocol for DCS

Answer 4

HBO shrinks bubbles
Increases pressure gradient of inert gases
Increases diffusion distance of oxygen into compromised tissue
Decreases reperfusion injury by blocking neutrophil attachment

Tx protocol
Earlier recompression = best outcome
Pain only gets table 5. Others table 6

Question 5

Air or gas embolism def and causes

Answer 5

Air or gas bubbles in the blood vessels

Pulmonary barotrauma during a reduction in pressure which allows air to escape into the vasculature

Accidental IV air injection during cardiopulmonary bypass, hemodialysis, central venous catheter placement or disconnection, GI endoscopy, various surgical procedures.
Significant decompression illness with patent foramen ovale or with buildup of bubbles in pulmonary circulation.

Question 6

AGE Sx and first aid

Answer 6

Arterial- immediate onset of Sx - loss of consciousness, confusion, focal neurological deficits, cardiac arrhythmias or ischemias. Variable depending on location of bubbles.

Venous- hypotension, tachypnea, hypocapnia, pulmonary edema, or cardiac arrest

First Aid - supplemental oxygen (maintains arterial oxygenation and creates a gas diffusion gradient. IV fluids. Supine position-NOT trendelenberg!! Left lateral decubitus for VGE

Question 7

Therapeutic mech and tx protocols for AGE/VGE

Answer 7

Shrinks bubbles, increases diffusion distance of oxygen into compromised tissue, increases pressure gradient of inert gases (nitrogen)

Tx - immediate compression, table 6

Question 8

CO and CN poisoning def and causes

Answer 8

Increased COHgb with history of exposure, acute or chronic. CO has greater than 200 x affinity for hemoglobin than oxygen. Fetal carb oxyhemoglobin will be higher than moms by 10-15%.

Caused by exposure from incomplete combustion; common sources are gasoline-powered engine exhausts, especially in enclosed, unventilated spaces; house fires; propane heaters

Question 9

CO and CN Sx and tx

Answer 9

Headache, chest pain, ischemic changes on EKG, neuro changes, coma, increased COHgb lab value (confirms exposure)

Remove from source of exposure, give 100% oxygen

Question 10

Therapeutic mechanisms for co/CN exposure

Answer 10

Increases pressure gradient of inert gases; increases diffusion distance of oxygen into compromised tissue (ESP brain and cardiac tissue). Causes vasoconstriction which reduces cerebral edema.

Half life of CO is 23 min breathing 100% at 3 ATA. 5 hrs 20 min on air 1 ATA. 1 hr 30 min 1 ATA oxygen

Question 11

Exceptional blood loss anemia def and causes

Answer 11

HgB <6 with clinical s/Sx of anemia

Marked loss of RBC mass by hemorrhage, hemolysis, or aplasia

Question 12

S/Sx of exceptional blood loss anemia and first aid

Answer 12

Altered mental status, ischemic EKG change, diarrhea from ischemic bowel, hypotension, diminished urinary output

100% oxygen

Question 13

Therapeutic mech of HBO for exceptional blood loss anemia

Answer 13

Hyper oxygenation increases diffusion distance of oxygen into compromised tissue. Oxygen being delivered by plasma. Oxygen content of plasma is proportional to partial pressure. At 3 ATA, po2 =2000 mmHg

Question 14

Clostridal myosotis and myonecrosis “gas gangrene” definition and causes

Answer 14

Infection of muscle tissue by anaerobic, spore forming, toxin-producing, gram +, encapsulated bacilli of the genus clostridium. Over 150 species, but most common is C. Perfrigens

Endogenous infection, caused from body contamination (bowel, etc), or an exogenous source, such as in a compound fracture.

Question 15

S/Sx and therapeutic mechanisms of gas gangrene

Answer 15

Sudden and severe pain to area. Pronounced swelling and edema. Hemorrhagic bullae or vesicles may be present. Rapidly advancing (1-6 in/hr) tissue necrosis caused by alpha toxin production. Thin, serosanguinous exudate with sickly, sweet odor. Gas on X-ray appears as feathers.

O2 tension of 250 mmHg is necessary to stop alpha-toxin production by organism. Improves WBC fxn. Bacteriostatic (inhibits bacterial growth). Causes vasoconstriction which reduces edema.

Question 16

Intracranial abscess, actinomycosis def and causes

Answer 16

Includes: cerebral abscess (pus in the brain); subdural empyema (pus between brain and meninges); and epidural empyema.

Result if sinus or bone infection of the skull. Usually bacteria introduced by trauma, surgery, or infection.

Actinomycosis usually caused by anaerobic bacterium Actinomyces israelii (found in nose and throat)

Question 17

Intracranial abscess s/Sx and therapeutic mech

Answer 17

Draining sinus track to the skin or mucous membranes. Fever. Weight loss. Minimal, if any, pain. Immunocompromised host.

Increases diffusion distance in compromised tissue. Improves WBC fxn. Causes vasoconstriction which reduces edema

Question 18

Necrotizing soft tissue infections def and causes

Answer 18

Acute infection of skin and subcutaneous tissues, by single strain or mixture if bacteria.

Caused by surgery or trauma (esp if foreign bodies introduced). Pt often compromised by diabetes, vasulopathy, or both.

Question 19

What is Fournier’s gangrene?

Answer 19

Rapidly advancing, mixed bacterial infection of the groin.

Question 20

Nec fasc therapeutic mech

Answer 20

Improves WBC fxn. Increases diffusion distance of oxygen into compromised tissues. Causes vasoconstriction. Encourages angiogenesis.

Question 21

CRO def and causes

Answer 21

Long standing bone infection nonresponsive to debridements and abx therapy. NOT acute osteo.

Hx of exposed bone via fx, surgery, disease process. Often pt has factors that compromise responsiveness to infection.

Question 22

CRO s/Sx and therapeutic mech of HBO

Answer 22

Previously documented osteo with appropriate debridement and abx therapy (gentamicin, tobramycin, anikacin - aminoglycosides commonly used). Hx of fracture with non-healing. Hx of healing and breakdown cycles. 3 phase bone scan, MRI, X-ray of osteo.

Enhanced leukocyte activity (increased WBC fxn). Increased diffusion distance of oxygen into comp tissue (commonly scar tissue)

Question 23

Crush injury, compartment syndrome, and other ATAPI def and causes

Answer 23

Injury to an area of the body which has caused the blood flow to be interrupted. It causes severe hypoxia to tissue distal to the injury, which may or may not have been injured.

Usually caused by trauma, arterial rupture; compression; edema

Question 24

S/sx of crush injury, etc

Answer 24

Edema, pain, reduced or absent pulses distal to site of injury, pallor, decreased cap refill

Question 25

Therapeutic mech of HBOT in crush injuries, ATPI

Answer 25

Increased diffusion distance of oxygen into compromised tissue. Encourages angiogenesis. Causes vasoconstriction which reduces edema. Decreases reperfusion injury. Increases WBC fxn. Accelerates demarcation of non-viable tissues

Question 26

Def and causes of selected problem wounds

Answer 26

A wound or ulcer that is failing to follow the normal reparative process due to inadequate oxygen availability.

Can have many causes but lack of blood flow is not life threatening or emergent.

Question 27

Problem wound s/sx and therapeutic mech of HBO

Answer 27

Many manifestations. Likely to see extremity with hair loss; tight, shiny skin; pale color; cool temp; thickened toenails; evidence of previous wound healing; reduced cap refill; reduced pulses

Increases diffusion distance of oxygen into compromised tissue. Encourages angiogenesis. Improves WBC function.

Question 28

Delayed radiation injury (soft tissue and bony necrosis) “strn and orn” def and causes

Answer 28

Tissue that is damaged by radiation

Caused by radiation, typically > 6,000 cGy

Question 29

STRN/ORN s/Sx and therapeutic mech

Answer 29

Skin that is shiny, tight, appears thin, pale, without hair, commonly referred to as 3 H tissue - hypoxic, hypocellular, hypovascular. Possible fistulas, varying amounts of pain.

Increase diffusion distance of oxygen into compromised tissues. Encourages angiogenesis. Improves WBC fxn

Question 30

Marx protocol

Answer 30

20/10 for prevention (pre-tooth extraction)

30/10 for existing ORN

Question 31

Compromised grafts and flaps - def and causes

Answer 31

Skin grafts can be partial or full thickness. Flaps can be free, pedicle, random, axial pattern flaps. Comp. flap/grafts show signs and Sx of tissue death after replacement into the recipient area.

Surgical attempts at wound closure.

Question 32

Comp flap/graft s/Sx and ther mech

Answer 32

Grafts will “slough” after only a few days <4 days. Pale, grey, purple, cyanotic and have poor cap refill.

Increases diffusion distance of oxygen into comp tissues. Encourages angiogenesis. Decreases reperfusion injury. Minimizes tissue loss.

Question 33

Thermal burns def and cause

Answer 33

Any destruction of skin by heat.

Exposure to heat sources.

Question 34

Thermal burns s/sx and ther mech

Answer 34

• Blistering and peeling of skin
• Copious exudates without odor
• Significant pain of partial thickness, no pain if full thickness
• Vasoconstriction reduces edema
• Increased diffusion distance of oxygen into compromised tissues
• Encourages angiogenesis
• Improves white blood cell function
• Minimizes surgical debridement and skin grafting.

Question 35

Pt selection with thermal burns

Answer 35

• > 20% of TBSA
• Hands, face, feet or perineum
• Partial or deep partial – second degree – full thickness burned tissue cannot be resurrected but zone of stasis can be minimized.

Question 36

Idiopathic Sudden Sensorineural Hearing Loss - IDIOPATHIC SUDDEN SENSORINEURAL HEARING LOSS

Patient selection

Answer 36

Patients with moderate to profound ISSHL (≥ 41 dB) who present within 14 days of symptom onset should be considered for HBO2. While patients presenting after this time may experience improvement when treated with HBO2, the medical literature suggests that early intervention is associated with improved outcomes. The best evidence supports the use of HBO2 within two weeks of symptom onset.