hyperbaric oxygen therapy
DESCRIPTION
Hyperbaric Oxygen Therapy By Sudarsan Agarwal Pinnamaneni Medical College VijayawadaTRANSCRIPT
Dr. SUDARSAN AGARWAL
Hyperbaric Oxygen Therapy
OverviewDefinitionHistoryBasics(Physics & Physiology)IndicationsContra IndicationsDetailsComplications Applications
Definition: The intermittent administration of 100% Oxygen at higher than atmospheric pressure, i.e. where oxygen dissolves in arterial blood plasma in increased amounts.
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History
BackgroundInitial discovery
1662 Henshaw built first hyperbaric chamber
Henshaw’s Domicilium
Background
1775 -Elemental Oxygen by
Joseph Pristley
Background
1777 –Name Oxygen was coined by
Antoine Lavoisier
Background1870-Surgical use Fontaine & Bert
Used for Wounds
1889 – Moir. Reduced mortality rate of decompression sickness from 25% to only 1.6% per year.
Background
Steel ball hospitalTimken Tank
Cunningham Sanitarium$ 1,000,000
Background1926 - Six-
story “steel ball hospital” Ohio.
72 rooms at pressures of 3 atm absolute.
1960 –Boerema
Pioneered the application of HBO to many medical problems.
Performs first surgery with HBO
• Discovered that Hgb wasn’t necessary for O2 transport
Background
Brummelkamp discovered effects on anaerobes
BacteriostaticTreat gas gangrene (Clostridium
perfringens)
In 60’s HBOT went out of practise because its use without adequate scientific validation.
Over last 20 years, animal studies, clinical trails and well validated clinical efficacy has proved efficacy of HBO in various ailments
Background
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BASICS
PhysiologyOxygen is carried by blood mainly in two
ways;HaemoglobinPlasma
Haemoglobin carries majority of oxygenPlasma carries only minute amounts of
oxygen.
Physiology
When we normally breathe air (with 21% O2) at sea level pressure, most tissue needs of Oxygen are met from the Oxygen combined to Hb, which is 95 % saturated.
100 ml blood carries 19 ml O2 combined with Hb and 0.32 ml dissolved in plasma.
1 gm of hemoglobin carries 1.34ml of oxygen.
15 gm of hemoglobin carries 20.10 ml of oxygen.
PhysiologyEven if we increase the pO2 , hemoglobin
cant carry more oxygen as it is 100% saturated.
Under barometric pressures, oxygen gets dissolved into plasma and thus this dissolved plasma oxygen is carried to different tissues.
The higher pressure during hyperbaric oxygen treatment pushes more oxygen into solution.
PhysicsDalton’s Law
Increasing the proportion of oxygen in the inhaled gas mixture increases its partial pressureAir at sea level is 21% O2HBO2 treatments use FiO2 100%
PhysicsHenry’s Law
Increasing the partial pressure of oxygen results in more oxygen dissolved in the blood
Physiology
This additional O2 in solution is almost sufficient to meet tissue needs without contribution from O2 bound to hemoglobin and is responsible for most of the beneficial effects of this therapy.
Total Pressure Content of Oxygen Dissolved in plasma (vol %)
Ata Breathing Air 100% Oxygen 1 0.32 2.09
2 0.81 4.44
3 1.31 6.80
Effect of Pressure on Arterial O2
Mechanisms for HBO Treatment 1. Oxygenation of Ischemic, Hypoxic Tissue -
HBO increases plasma and tissue oxygen tensions 10 times which helps tissues to maintain tissue viability without RBC’s
2. Neutrophil Oxidative Killing - Neutrophils regain ability to kill bacteria by generation of oxygen dependent superoxides and peroxides.
3. Suppression of multiplication in bacteria- High oxygen tensions suppress growth of streptococcus and anerobes
Mechanisms for HBO Treatment 4. Augmentation of Antibiotic effectiveness-
Increased oxygen tension allows oxygen dependent active transport to bring in antibiotic across bacterial cell wall.
5. Enhanced fibroblast function- prevents unnecessary cicatrix formation.
6. Angiogenesis- Increased oxygen tension increases vascular endothelial grow factor function as well as secretion of matrix by fibroblasts
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Indications
Partial List of Conditions for Which Hyperbaric Oxygen Has Been UsedGas-bubble disease Air embolismDecompression sickness
Poisoning Carbon monoxide
CyanideCarbon tetrachloride
Hydrogen sulfideInfections Clostridial myonecrosis
Other soft tissue necrotizing infectionsRefractory chronic osteomyelitis Intracranial abscess
Mucormycosis
Partial List of Conditions for Which Hyperbaric Oxygen Has Been UsedAcute ischemia Crush injury
Compromised skin flaps Central retinal artery occlusion, central retinal vein occlusion
Chronic ischemia Radiation necrosis (soft tissue, radiation cystitis, and
osteoradionecrosis) Ischemic ulcers, including diabetic ulcers
Acute hypoxia Exceptional blood loss anemia (when transfusion delayed or
unavailable) Support of oxygenation during therapeutic lung lavage
Thermal injury Burns
Envenomation Brown recluse spider bite
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CONTRAINDICATIONS
Contraindications
*One absolute contraindication is Pneumothorax
Converts it into Tension Pneumothorax
DRUGS Alcohol
Nicotine
Cis-platinum
Doxorubicin
Bleomycin
Aromatic hydrocarbons
Disulfiram
Steroids
*Malignant tumors
*Acidosis
*History of thoracic surgeries
*Pregnancy
*Hereditary spherocytosis
*Optic neuritis
*Malignant tumors
*Claustrophobia
*History of spontaneous pneumothorax
*Copd
*Seizure disorders
*URT infection
*Hyperthermia
*Hypothermia
Contraindications
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DETAILS
How is HBO administered ??? •Two types of hyperbaric chambers:
Monoplace and multiplace
Monoplac
e
Two seater
Multi place
Multi place
Initial compression for 30 minutesTreatment for 90 minutes with air breaks
(10 minutes every 30 minutes is standard)Decompression for 30 minutesAll regimens use 100% O2 Pressure -
Most use 2.4 atmMaximum tolerated is 3 atm4 atm induces seizures
Process of treatment
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COMPLICATIONS
Mild problems : Claustrophobia (in monoplace chambers),FatigueHeadache. More serious complications: Myopia that can last for weeks or months, Sinus damage, Ruptured middle ear, and Lung damage. Major complication: Oxygen toxicity can result in convulsions, fluid in
the lungs, and even respiratory failure.
ComplicationsMiddle ear barotrauma
Middle ear barotrauma is the most common adverse effect
As ambient pressure within the chamber increases, patient must be able to equalize the pressure in his/her middle ear
Boyles Law: A volume of gas in a closed space will decrease as pressure increases P1V1=P2V2 Problems with air filled spaces beneath dental fillings, middle ear and sinuses.
If not, pressure gradient develops across the tympanic membrane. Pain followed by hemorrhage or serous effusion develops
Remedy: To teach valsalva maneuver Ventilated patients require myringotomyPrevention: Teaching patient auto-
insufflation technique or use of decongestants. If auto-insufflation fails, tympanostomy tubes are placed.
Complications
Lung Barotrauma
Elevated pressures may damage alveoliAlveolar
hemorrhageHemoptysis
PneumothoraxPulmonary
interstitial emphysema
Tension Pneumothorax
ComplicationsEyes
Lens deformation causes temporary myopiaProgressive myopia has been reported in
patients undergoing repetitive daily therapyReversible within 6 weeks of discontinuing
treatment
Oxygen toxicity.
It is interesting that while o2 is necessary for life in aerobic organisms, it is also toxic.
1878 -Paul Bert: The Father of Pressure Physiology observed convulsions and death in animals at a constant 3-4 atmospheres of pressure.
Broncho pulmonary dysplasia
Retinopathy of pre maturity.(Retrolental fibroplasi)
Fire RiskPerfect set up for fire (especially
monoplace)100% oxygenHighly pressurizedEnclosed space
Rare…50 deaths due to HBO2-related fires since 1980Must remove all flammable materialsFire safety protocol is essential
Risk reduced in multiplace chambersChamber pressurizedO2 delivered individually via tight-fitting masksAttendants may enter in an emergency
CostsHBO2 is relatively expensive…
Monoplace chamber > $150,000Most facilities have multiplace chambers,
which can cost millionsEach 30 min costs ~ $170Average full course is 30 dives of 90 minMultiplace chamber for ~$15,300
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APPLICATIONS
Carbon Monoxide PoisoningCarbon monoxide poisoning is the leading
cause of injury and death by poisoning in the world
Affinity of CO for hemoglobin (forming carboxyhemoglobin) is 200 times that of oxygen.
Carbon Monoxide PoisoningSupplemental oxygen is first line therapyHBO causes carboxyhemoglobin dissociation
to occur faster than pure oxygen at sea level pressure.
Breathing Gas Mean Half-life Air, 1 ATA 214 minOxygen, 1 ATA 43 minOxygen, 2.5 ATA 19 min
Decompression sicknessDecompression sickness (caisson disease or “the bends”)
is attributed to formation of nitrogen bubbles in the body on decompression.
Occurs in divers, miners and astronauts
•Diver resurfaces too quickly, Gas bubbles form in tissue and blood and it Blocks lymphatics, veins and arteries
•Treatment of choice is HBO
• HBOT
• Reduces bubble size
• Corrects hypoxia
Gas embolismAir embolism may be caused by sudden
decompression or ascent in diving, trauma like head and neck injuries, high altitude accidents or may be iatrogenic during a diagnostic or surgical procedure.
Air emboli may lodge distally in the smaller arteries and arterioles of brain and obstruct the flow of blood resulting in ischemia, hypoxia and cerebral edema.
The bubble may also act as a foreign body and start a number of chemical reactions.
Gas embolismHBO is the first line of treatment in these
conditions. Under hyperbaric conditions, oxygen diffuses into the bubbles, displacing the nitrogen from the bubble and into solution in the blood.
HBO induced vasoconstriction inhibits air embolus redistribution and decreases cerebral edema.
High O2 counteracts the ischemic and hypoxic effects of vascular obstruction.
It also reduces blood sludging and improves WBC function.
Clostridial Myonecrosis (Gas gangrene)Prompt recognition is importantAnaerobic bacteria are especially sensitive to
increased tissue PO2. Diffused oxygen which raises capillary p02 levels
at the wound site, stimulates capillary budding and granulation of new, healthy tissue.
High O2 tensions inhibit clostridial α-toxin production. reversal of hypoxia-induced neutrophil
function,
enhanced macrophage interleukin (IL)-10 expression,and
anti-inflammatory effects.
Necrotizing Fasciitis andFournier’s gangrene
MucormycosisAnerobesStreptococci
Chronic UlcersOxygen is required for angiogenesis (which is
fostered by the increased oxygen gradient), collagen deposition, re-epithelialization, cellular respiration, and oxidative killing of bacteria.
Decreased edema noted following hyperbaric treatment allows better diffusion of oxygen and nutrients through tissues while also relieving pressure on surrounding vessels and structures.
In this light, HBO has been used for treating foot ulcers in patients with diabetes, venous and arterial insufficiencies, burn wounds, crush injuries, marginal flaps, and skin grafts.
Chronic Ulcers
Chronic UlcersProblem: Not all infections are anaerobic.
Wounds with DiabetesFoot wounds of patients with diabetes offer a
particularly difficult problem. These patients often have an impaired
immune system, predisposing them to infections.
Blood supply to the wounds is hindered by large and small disease.
The red blood cells are sticky and nonpliable, which leads to capillary occlusion and distal ischemia.
Neuropathies render the foot insensate and impair motor function.
This impaired motor function flattens the foot so that the metatarsal heads become prominent and promote further susceptibility to ulceration via pressure.
Blood loss anemiaIntermittent hyperbaric therapy exposures
have been used to relieve temporary physiologic stress from acute anemia
Rarely used for this purpose
May be useful when crossmatching incompatibilities and religious beliefs prevent blood transfusions(Jahova)
Crush injury
HBO is used in limited degree for acute traumatic peripheral ischemia and suturing of severed limbs.
Reduces infection and wound dehiscence and improves healing
Improves oxygenation to hypoperfused tissue
Causes arterial hyperoxia causing vasoconstriction and decreased edema formation.Also, intermittent pressure stimulates
circulation and reduces edema.Early use of HBO may reduce
compartment pressures enough to avoid fasciotomy.
Trauma Physiological response Vasoconstriction Hypoxia
Ischemia Swelling cuts off O2 circulation to the affected areas
O2 leads to… Collagen deposition/synthesis Angiogenesis/epithelization AP Recovery time
Performance
Speeds recovery between workouts
Sports Injuries
OsteoradionecrosisDamage to osteocytes from Radio therapyDoes not affect necrotic boneTarget is the viable bone and soft tissueGoal is to revascularize radiated tissues and to
improve fibroblastic densityHealing process requires oxygen for:
Differentiation of fibroblastsSynthesis of collagen
20 “dives” before treatment/10 “dives” after radiotherapy
2.5-2.8 ATA for 90-120 minutes.
Radiation necrosis
Skin Grafts & Free FlapsPathophysiology
Grafted or transplanted tissue may be healthyBut… implantation site may be hypoxic
Due to tissue bed disease, vasospasm, edema, infection
Oxygen & nutrient supply compromisedMust establish vascular connection for survival
HBO2 MechanismImproves tissue PO2Promotes angiogenesisAugments immune response & limits
inflammation
Radiation SensitizationAmong first studied uses of HBO2 (1960’s)
Hypoxia increases the resistance of cancer to radiotherapy.
Increasing oxygen pressure in the tumor can aid tumoricidal therapiesIncrease FiO2, increase ambient pressure Administration of radiation sensitizing agents
Tumor Growth !?Data are conflicting
Handful of case reports suggest growth (Promoting angiogenesis in tumor cells)
Other reports suggest tumor suppression
Brown recluse spider bite
Loxosceles reclusa/ Necrotic arachnidism/ Violin Spider/ fiddleback spider
Routine treatment should include elevation and immobilization of the affected limb, application of ice, local wound care, and tetanus prophylaxis. Many other therapies have been used with varying degrees of success including HBO , Debridement and antivenom
Role of HBO is still controversial
AutismCharacterised by impairment in social interaction,
difficulty in communication and restrictive and repititive behaviours.
HBOT shown significant improvement in Speech and cognitive awareness
Still under study
Gamow Bags, a rescue product for high-altitude climbers and trekkers, is used for the treatment of moderate to extreme altitude sickness. By increasing air pressure around the patient, the Bag simulates descents as much as 7,000 feet
Various regimens
2.0 ATA oxygen X 90 minutes wound healing comprised skin grafts thermal burns osteomyelitis crush injury/compartment
syndrome
2.5 ATA oxygen X 90 minutes nonclostridial gas gangrene necrotizing infections osteomyelitis radiation tissue injury
3.0 ATA oxygen X 90 minutes carbon monoxide poisoning clostridial gas gangrene
*Average 90 min. HBOT Rx = $300 - $400
* Most ailments require 30-40 sessions
Conclusion
We can use HBO effectively in
• Air embolism
• Decompression sickness
• CO poisioning
• Radiation necrosis
• Chronic ulcers
References Miller s Anesthesia Ganong Physiology Harrison Sabiston Pubmed Wikipedia
THANK YOU
The pressure is on to prove that it works.
Indications for Hyperbaric Oxygen Therapy A. UNIVERSALLY ACCEPTED: These indications are supported with peer reviewed proof of efficacy Wounds: • Problem, non-healing wounds and ulcers (diabetic, venous etc) • Infective wounds - gas gangrene, refractory osteomyelitis, necrotising soft tissue infections • Acute traumatic ischemias, crush injuries, compartment syndromes • Compromised skin grafts and flaps • Thermal burns Oncology: • Late radiation induced tissue damage and complications due to endarteritis • Prophylactically adjunctive to therapeutic radiation, for preparation of surgery or implant procedures in previously irradiated fields Primary Line of Treatment: • Air or gas embolism • Decompression Sickness • Carbon Monoxide poisoning, smoke inhalation Other Indications • Acute Sensorineural Hearing Loss • Intracranial Absceses • Bells Palsy B. RESEARCH INDICATIONS: Role of HBOT in these indications is being studied in international trials• HBOT in neurological illnesses – cerebral palsy, stroke, head injury • HBOT as a radiosensitiser in Glioblastoma mutiforme and re-irradiation of sqamous cell Ca