Hyperbaric Oxygen Therapy and Negative Pressure Wound Therapy Flashcards
What is hyperbaric oxygen (HBO) therapy?
Oxygen under pressure
Use in clinical medicine came about in 1955
- Increased oxygen environments to augment the effects of radiation therapy treatments in cancer patients
Tremendous growth since 1960s, but problems and criticism over utilization and regulatory issues
What did the “Report of the committee on hyperbaric oxygenation” (published in 1977) state?
Divided disorders treated by HBO into 4 categories:
- Category 1 : disorders for which there was no question of HBO efficacy
- Category 2 : disorders for which there is no supporting evidence whatsoever
This report has been updated periodically
Currently contains 14 disorders presently approved for HBO therapy
What are the approved conditions outlined by the Undersea and Hyperbaric Medical Society (UHMC) for HBO?
Air or gas embolism
CO poisoning
Gas gangrene
Crush injury, compartment syndrome, and other acute traumatic ischemias
Decompression sickness
Arterial insufficiencies
Severe anemia
Intracranial abscess
Decrotizing soft tissue infections
Osteomyelitis (refractory)
Delayed radiation injury (soft tissue and bony necrosis)
Comprised grafts and flaps
Acute thermal burn injuries
Idiopathic sudden sensorineural hearing loss
What are the general principles of hyperbaric oxygenation?
When inside the chamber, the patient breathes 100% oxygen intermittently at a pressure higher than at sea level
The literature supports the type of HBO therapy in which a patient is:
- In a chamber
- Breathing elevated partial pressures of oxygen
- Through an intact cardiopulmonary system
Topical high-pressure oxygen and containers enclosing individual limbs are not considered HBO therapy
- No data to support use
What is some of the equipment used for HBO?
Monoplace chamber
- Treat one person at a time
Multiplace chamber
- Able to treat as many as 20 or more patients simultaneously
What are the characteristics of a HBO Monoplace chamber?
Free cylindrical unit
Steel end caps
Thick, cylindrical acrylic hull
Possible to administer IV fluids, monitor BP, even mechanically ventilate an intubated patient
What are the characteristics of a HBO Multiplace chamber?
Patients typically seated in special seats along the wall
Due to volume, these chambers are compressed with medical-grade air instead of oxygen
100 percent of oxygen is administered through an air mask or a hood
What are the physiologic effects of HBO?
Mechanical effects of reducing bubble size
- Occurring in decompression sickness or air emboli
- Effects on gas bubble size
- Increased dissolved oxygen in plasma
Effects of an increased partial pressure of oxygen
- Varies by organ system and disorder being treated
At higher atmospheric pressure, oxygen develops pharmacologic properties
- Must be dosed appropriately to avoid complications
What are the effects due to elevated partial pressures of oxygen?
The clinical administration of HBO is limited to a max pressure of 3 ATA (atmospheres absolute)
- Greater than 3 ATAs increased the toxic effects of oxygen
What are the effects of HBO on blood flow to the tissues?
VASOCONSTRICTING, BUT…
Compensating for by the increased oxygen dissolved in the plasma tissues
Good for hypoxic wounds
- Forms new microcirulation
- Angiogenesis is accelerated by hyperoxygenation
- Shortens healing time
What are the effects of HBO on Gas Gangrene?
Rapidly progressive and life-threatening bacterial disorder
Caused by the anaerobic bacteria CLOSTRIDIUM PERFINGENS
HBO inhibits the alpha-toxin produced by the bacterium
Direct bacterial killing effect
How does HBO improve viability of skin flaps?
Increased production of an antioxidant in the HBO environment that has measured in increased quantities in preserved tissue flaps
Improved microvascular perfusion in ischemic rat skin flaps
What is the physiological impact of oxygen in wound healing?
Collagen deposition
- Increase in partial pressure of oxygen
- Accelerates fibroblast replication–increased collagen synthesis
- Leads to granulation, neovascularization, and epithelialization
Immune response
- Increased cellular oxygen levels increases leukocyte bacterial killing and gram negative organisms
Mediation of cytokine activity
Angiogenesis in irradiated tissues
HBO can be applied in what select wound types?
LE diabetic wounds
Arterial insufficiency ulcers
Delayed radiation injury
Clostridial gas gangrene
Chronic refractory osteomyelitis
Compromised skin grafts and flaps
Thermal burn injuries
What are adverse effects of HBO by system?
CNS
- Visual changes, tinnitus, nausea, twitching, irritability, dizziness, seizure
Pulmonary
- Coughing, SOB, bronchial irritation
Ocular
- Retinal damage in premature infants, myopia (nearsidedness), nuclear cataracts
What are the relative contraindications of HBO?
Emphysema
History of spontaneous pneumothorax
High fever
Optic neuritis
Active respiratory and sinusitis
History of ear surgery
Seizure disorders
CHF
Uncontrolled HTN
Pregnancy
What are the absolute contraindications for HBO?
Untreated pneumothorax
Concomitant treatment with Doxorubicin
- Chemotherapy drug
Concomitant or recent treatment with Bleomycin
- Cancer medication
What are the benefits of Negative Pressure Wound Therapy (NPWT)?
Promotion of moist wound healing
Reduction of edema and interstitial fluid
Increased local perfusion
Approximation of wound edges
Stimulation of granulation tissue formation
Reduction of bacterial load
Reduction in the frequency of dressing changes
What is the theory behind NPWT?
Removal of fluid
- Interstitial edema is reduced
- Inflammatory mediators and bacteria removed
Mechanical stimulation of cells
- Encourages cell proliferation, granulation tissue formation, and wound contraction
Occlusion of the wound from environmental contaminants
What are the effects of NPWT at the tissue level?
Occlusion
- Airtight seal to maintain moist healing environment
- Dressing is changed every 48-72 hours–exposure to air is reduced
Cellular deformation (Suction force = stretching force on cells)
- Increases release of growth factors and cytokines associated with cell proliferation
- Increased cellular division and migration of macrophages, lymphocytes, and fibroblasts
- Increased angiogenesis and granulation tissue formation
Fluid removal
- Removal of edema facilitates oxygen and nutrient diffusion
- Proliferation of lymph vessels
- Opening of collapsed lymph vessels in CVI wounds
Circulation
Wound contractions
Bioburden
What are the indications for NPWT?
ACUTE SURGICAL WOUNDS:
- Grafts and flaps
- Fasciotomies
- Open abdominal wounds
- Full thickness wounds with and without exposed structures
- Deep partial and full-thickness burns
- Traumatic amputations
- Over skin substitutes
CHRONIC WOUNDS
- Debrided neuropathic wounds
- Open amputation sites related to diabetes
- Stage 3 and 4 pressure injuries
- Venous and arterial insufficiency ulcers
What are the precautions of NPWT?
Anticoagulants
Low platelet count
Over bone, tendon, organs, vessels
Rate and type of drainage collection
Monitor skin condition when dressing placed over bony prominences
What are the contraindications of NPWT?
Wounds with 30 percent necrotic tissue
Unrelated osteomyelitis
Lack of hemostasis
Directly over exposed vessels, bypass grafts, organs, etc.
Ischemic wounds with proximal occlusion
What are the components of NPWT?
Suction device
Wound filler
Occlusive sheet cover
Tubing
Collection canister
What is the continuous mode of suction delivery?
Advantages:
- Continuous fluid collection with heavily exuding wounds, single compression cycle–decreases pain, provides stability to the wound (may allow for increased mobility of patient)
Disadvantage:
- Slower granulation formation compared to intermittent therapy
What is the intermittent mode of suction delivery?
Advantages:
- Cyclic compression good for wounds with decreased circulation, increased mechanical stimulation–increased rate of granulation
Disadvantages:
- Airtight sheet can loosen, more prone to leaks due to increase pooling of heavily exuding wounds, potential for pain, may disrupt sleep
What is the variable mode of suction delivery?
Advantages:
- Benefits of intermittent, but maintenance of low pressure continuous
What is the instillation mode of suction delivery?
Advantages:
- Allows automatic periodic topical irrigation of wound tissues with normal saline or antibacterial solutions, may lead to increased granulation due to frequent irrigation and removal of fluids
Disadvantages:
- May cause maceration and loosening of the occlusive sheet as a result of the extra fluid pumped into the foam
What are the different kinds of wound fillers?
Black foam
- Promotes granulation tissue formation and produces less dense and organized granulation tissue compared to gauze
- Decreased integrity = possibility of breaking off into the wound
White foam
- Less aggressive, less adherence in tunnels, tracts, or undermining
- Slower granulation compared to black foam
Antimicrobial gauze
- Produces thinner, denser, more organized granulation tissue but at a slower rate
- Gauze fibers can shed into the wound bed
What are the basic steps to NPWT application?
Prep wound bed
Prep periwound skin
Apply non-adherent protective layer
Apply wound filler
Apply occlusive sheeting 3-5 cm past wound edge
Apply top mounted drain
Connect tubing to NPWT suction/canister
Turn on and ensure a good seal
