hbot) hyperbaric oxygen therapy

مؤتمر الطب الفيزيائي وإعادة التأهيل العربي باألر دن

(HBOT )Hyper Baric Oxygen Therapy

Dr Faeyz F Orabi MD, PM&R

1/10/2012

History of HBOTWhat is HBOT?How HBOT Works?Trends in Hyperbaric Medicine

(HBOT )Hyper Baric Oxygen Therapy

History of Hyperbaric Therapy

British physician, Henshaw, in 1662 used a chamber fitted with a large pair of organ bellows, so that air could either be compressed into the chamber or extracted from it. In this ‘domicilium' increased pressures were used for the

treatment of acute disease, and reduced pressures for the treatment of chronic diseases.

Oxygen discovered in 1775

1889 – Moir used hyperbaric therapy to treat workers building railroad tunnels underneath the Hudson River. Reduced mortality rate of decompression sickness from 25% to only 1.6% per year.

1926 - Six-story “steel ball hospital” in Cleveland, Ohio. The facility was capable of treating patients in 72 rooms over 12 floors at pressures of 3 atm absolute.

..No oxygen? Brain damage in 3-4 minutes.

..No vitamin C? Scurvy in 3-4 months.

..No vitamin D? Osteoporosis in 3-4 years.We can supplement vitamins and

minerals, but…How do you get more

Oxygen?????

The brain makes up

2% of body weight but uses 20% of

body oxygen

Room Air 160 mmHg

Lung Capillaries 100 mmHg

Leaving Heart 85 mmHg

Peripheral Arterioles 70 mmHg

Organ Capillaries 50 mmHg

Cells 1-10 mmHg

Mitochondria 0.5 mmHg(0.3% of inhaled oxygen)

Mitochondria is the final

site of energy production

Breathing more oxygen not enough. Room air contains 21% oxygen, enough to fill most of the oxygen-binding sites on our red blood cells, carried by hemoglobin. Breathing even 100% oxygen Fills the few remaining sites on hemoglobin. Increases blood oxygen by a small percentage. Can be life-saving, especially if blood oxygen levels are low, but results in minimal gains when O2 levels start out normal. Encourage oxygen to dissolve in serum and plasma by

increasing pressure of oxygen.Pressure is provided by a chamber with above-normal pressure, called a “hyperbaric” oxygen chamber. Patient enters chamber and pressure is slowly increased to a level appropriate for the person’s condition.

How To Get More Oxygen?

Hyperbaric Oxygen Therapy(HBO)

Involves intermittently breathing pure oxygen at greater than ambient pressure

Think of oxygen as a drug and the hyperbaric chamber as a dosing device

Elevating tissue oxygen tension is the primary effect

Hyperbaric oxygen therapy (HBOT) is the inhalation of 100 percent oxygen inside a hyperbaric chamber that is pressurized to greater than 1 atmosphere (atm). HBOT causes both mechanical and physiologic effects by inducing a state of increased pressure and hyperoxia. HBOT is typically administered at 1 to 3 atm. While the duration of an HBOT session is typically 90 to 120 minutes, the duration, frequency, and cumulative number of sessions have not been standardized.

What is HBOT?

What is HBOT? How HBOT Works? Trends in Hyperbaric Medicine

(HBOT )Hyper Baric Oxygen Therapy

Basic Mechanisms Boyle’s Law – pressure and

volume inversely proportional under constant temperature By increasing ambient

pressure to 2 atm, decreases the volume by ½

Therapeutic for bubble forming diseases such as decompression sickness or arterial gas embolism

Henry’s Law – at a given temperature, the amount of gas dissolved in solute is directly proportional to the partial pressure of the gas. By increasing ambient

pressure, more oxygen can be dissolved in the plasma

Solubilty of Gas (equilibirium

concentation): C = KH Pgas

Pressurized OxygenCapillary Pressure Oxygen

Pressure Oxygen%

50 mm Hg pO2 Normal Air

75 mm Hg pO2 1 Atmos . 100% O2

246 mm Hg pO2 1.3 Atmos . 100% O2

437.5 mm Hg pO2 1.5 Atmos . 100% O2

pres

sure

O2

abso

rpti

on

What does this have in common?

HBOT

Tissue Compromise

• Hypoxia – generates signal to commence wound healing cascade • Hyperbaric Oxygen environment augments the signal• Action – HBOT acts as a signal transducer.

Recent studies suggest low oxygen state after a stroke, cerebral palsy, autism, or chronic viral infections. Some of the cells around the area of injury are still alive - not sufficient oxygen to function well. Not dead, but too little oxygen to do their jobs. Thousands of people are affected every year by an event or condition that causes some body tissues to live in a perpetually-low oxygen state. Can be improved with acceptable blood flow, oxygen saturation.•Limb reattachment•Radiation therapy•Head injury•Surgical wound•Skin graft •Plastic surgery•Severe burns•Carbon-monoxide poisoning

The macrophage is sensitive to variations in levels of oxygen present in the tissues; sensitive to an oxygen gradientPersistent Hypoxia signal results in an attempt , by local tissues to build new blood supply to the affected area.This is how tissues communicate to other neighboring structures, the need for routine tissue repair to commence.

Note that although there may be insufficient stimulus to initiate the tissue repair cascade under normal conditions, by increasing the local oxygen delivery the oxygen gradient is magnified ….resulting in a stronger signal and augmented repair.

Clinical Hyperbaric Oxygen Therapy

Emergency IndicationsDiving injury

Carbon monoxide poisoningSurgical infections

Acute traumatic ischemiaFailed flaps and grafts

Cerebral Edema Burns

Scheduled Indications:Generally related to healing of

compromised wounds

Uses

Certain non-healing wounds (post-surgical or diabetic)

Radiation soft tissue necrosis and radiation osteonecrosis

Necrotizing fasciitis (flesh eating bacteria)

Carbon monoxide poisoning Decompression sickness Air or gas embolism

Uses

Acute arterial ischemia (crush injury, compartment syndrome, etc.)

Compromised skin grafts or flaps Severe infection by anaerobic

bacteria (such as gas gangrene) Severe uncorrected anemia when

blood transfusion is not available (e.g., in a Jehovah's Witness)

Chronic refractory Osteomyelitis

HBOT and Medicare An HBOT session costs anywhere from $100 to $300 in private clinics, to over $1,000 in hospitals. More U.S. physicians are lawfully prescribing HBOT for "off label" conditions such as Lyme Disease and stroke. Such patients are treated in outpatient clinics, however it is unlikely that their medical

insurance will pay for off label treatments .

ControversialHBOT is controversial and health policy regarding its

uses is politically charged. Both sides of the controversy on the effectiveness of HBOT is available

in the form of PUBMED and the Cochrane reviews, a discussion of Multiple Sclerosis in particular.

Mechanism and Effects

Hyper-oxygenation Greater oxygen carrying capacity

Increased oxygen diffusion in tissue fluid

Diffusion distance proportional to the square root of dissolved oxygen

Severe blood loss anemia (unable to carry oxygen)

Crush injury, compartment syndrome graft, and flap salvage (decreased perfusion)

Mechanism and Effects

Edema (increased diffusion barrier)

Decrease gas bubble sizeBoyle law - Gas volume inversely proportional to pressure

Hyperbaric diffusion gradient favors gas leaving the bubble and oxygen moving in, metabolizing oxygen in the bubble

Decompression sickness Air embolus syndrome

Secondary Effects

VasoconstrictionDecreased inflow into tissues Decreased edemaIncreased oxygen gradient between

wound and surrounding environment Increased fibroblast proliferation

leading to increased collagen deposition and increased fibronectin, which aids in neovascularization

Additional Effects

Leukocyte oxidative killingIncreased oxygen free radicals Anaerobes lack superoxide dismutase to

control oxygen free radicals (Necrotizing soft-tissue infections)

Toxin inhibitionDecreased clostridial alpha toxins (gas

gangrene) Decreased cardio toxinsAntibiotic synergy

Mechanism of action

Angiogenesis in ischemic tissuesBacteriostatic/bactericidal actionsCarboxyhemoglobin dissociation hastenedClostridium perfringens alpha toxin synthesis

inhibitedVasoconstrictionTemporary inhibition of neutrophil Beta 2

integrin adhesion

Published clinical studies describing results from treating stroke patients with hyperbaric oxygen, performed at 11 different hyperbaric centers, were analyzed for benefit (a total of 265 patients). The cumulative amount of hyperbaric oxygen therapy (DHBOT) was calculated by multiplying chamber oxygen pressure (ATA) times the duration of each HBOT (in hours), times the total number of hyperbaric treatments. Efficacy of HBOT (EfHBOT) was computed from the number of patients in each study who showed significant clinical improvement of their neurologic status as a result of HBOT (percentage of the total number of patients who improved). The amount of benefit was compared with the total amount of HBOT. Analysis showed that benefit increased progressively as more treatments were given, as graphically depicted below.

Research Report of Hyperbaric Oxygen Benefit for Stroke Victims

From the graphic plot above it can be seen that average improvement increased with each treatment and that 30 one-hour HBOT treatments resulted in progressive benefit. For many patients that benefit continued to increase with additional therapy and 30 treatments is not usually considered adequate for full benefit.

Migraine and cluster headaches are severe and disabling. Both hyperbaric oxygen therapy (HBOT) and normal pressure oxygen therapy (NBOT) have been suggested as effective treatments to end acute attacks and prevent future attacks. HBOT involves people breathing pure oxygen in a specially designed chamber. In our review, we found some weak evidence to suggest that HBOT helps people with acute migraine headaches and possibly cluster headaches, and that NBOT may help people with cluster headache. We found no evidence that either can prevent future attacks. Because many migraines can be treated simply with appropriate drug therapy, further research is needed to help choose the most appropriate patients (if any) to receive HBOT.

Normal pressure oxygen therapy and hyperbaric oxygen therapy for

migraine and cluster headaches

This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2011 Issue 10, Copyright © 2011 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).