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