INTRODUCTION:

The history of hyperbaric medicine is closely linked with technology for underwater activities and advance knowledge about physics laws and physiological mechanism of breathing oxygen. In 1775 black discovers carbon dioxide, Priestly discovers oxygen and in 1789 Lavoisier describes oxidative phenomena.^[1]

Figure 1:

Hyperbaric oxygen therapy (HBOT) involves breathing pure oxygen in a pressurized room or tube. Hyperbaric oxygen therapy was initially discovered in 1662 by Henshaw. He builds the first hyperbaric oxygen chamber. English physician and clergyman called the chamber the “Domicilum”. Later on in 1775, it was used for various purpose of elemental oxygen. Joseph Pristley used HBOT for surgical purpose for prolong anesthesia and improved surgical outcomes by increased wound healing and decompressive sickness to reduced morbidity of decompression.

DEFINITION:

Hyperbaric Oxygen therapy (HBOT) is defined as method of oxygen administration in which 100% oxygen is administered to a patient placed inside a chamber pressurized to greater than 1 atmosphere, where oxygen dissolves in arterial blood plasma in increased amounts.

MECHANISM OF ACTION:

With hyperbaric oxygen therapy (HBOT) in cardiopulmonary it increase PaO₂ by increase Hb 97% saturated at atmospheric pressure and increased in dissolved O₂ by PaO₂ of 100mm Hg. Using 100% FiO₂ at 3 atmospheric pressure up to 2000mmHg increase O₂ from 3ml/L blood to 60ml/L, its 20 times more O₂ circulating in plasma.

All gases follow fundamental gas law:

Boyle’s Law:

A volume of gas is inversely proportional to pressure at constant temperature.

PV=k

Where P is pressure, V is volume and k is a constant representative of the pressure and volume of the system.30

· Dalton’s law states increasing the proportion of oxygen in the inhaled gas mixture increases its partial pressure as air at sea level is 21% oxygen and in HBOT use FiO₂ 100%.

· Henry’s law states increasing the partial pressure of oxygen results in more oxygen dissolved in the blood. This additional O2 in solution is almost sufficient to meet tissue needs without contribution from O2 bound to haemoglobin and is responsible for most of the beneficial effects of this therapy. Three main gases of concern in HBOT are oxygen, Carbon dioxide and nitrogen.

Main mechanism in hyperbaric oxygen therapy are:

· Increased oxygen tension

· Vasoconstriction

· Increased fibroblast replication

· Increased collagen response

· Angiogenesis

· Enhanced leukocyte function

· Attenuation of reperfusion injury

· Increasing pressure and gas gradients (to decrease bubble size and increase off-gassing of bubble content)

PHYSIOLOGICAL EFFECTS OF HBOT:

Delivery of O₂ to hypoperfused tissues by limiting ischemic damage, cell death and inflammation. It also promotes collagen synthesis and angiogenesis. Decrease lactate production and tissue acidosis. HBOT generates oxygen free radicals which dependent killing bacteria and facilitates oxygen dependent transport of antibiotics. Also causes vasoconstriction by limiting leukocyte adhesion and degrannulation and decreases tissue edema.

DOSING AND DELIVERY:

The dosing varies by indication and may be given daily or BID. All regimens used delivery of oxygen 100% and pressure at 2.4 ATA to 3 ATA at maximum tolerated but 4 ATA induces seizures. It begins initially with compression for 10 minutes. The treatment phase is for 90 minutes with air breaks for 10 minutes every 30 minutes is standard for air breaks and ends with decompression for 10 minutes. There are two types of chambers: Monoplace and Multiple Chambers (Fig:1). Some advantages for monoplace chamber are like maintaining privacy, comfortable; isolation ensures no infection spread and technically easier as no use of restraining mask which is used in multiple chambers and ideal for acute stages illness or injury.

Figure: A

Figure: BFigure: A. Monoplace and B. Multiple Chamber.

INDICATIONS/ APPLICATIONS:

The centre for medicare and Medicaid services (CMS) and undersea and hyperbaric medical society (UHMS) recommended indications for hyperbaric oxygen therapy^[2]

· Air or gas embolism

· Carbon monoxide poisoning and complicated by cyanide poisoning.

· Clostridial mysositis and myonecrosis(gas gangrene)

· Crush injury, compartment syndrome and other acute traumatic ischemia

· Neurological Decompressive Sickness

· Necrotizing soft tissue infections

· Diabetes gangrene

· Osteomyelitis

· Delayed radiation injury

· Skin graft and flaps

· Acute arterial insufficiency

· Intracranial abscess

The use of hyperbaric oxygen therapy (HBOT) in Neurodisorders which demonstrates pre-clinical effectiveness for the treatment of acute ischemic stroke and reports reductions in oxidative stress, inflammation, and neural apoptosis. These pathophysiological benefits contribute to improved functional recovery.^[3]

HBOT has neuroprotective effects without increased oxygen toxicity in traumatic brain injury (TBI) models when administered at pressures less than 3 ATA. The improved tissue oxygenation and cellular metabolism, anti-inflammation, anti-apoptosis and promoting neurogenesis and angiogenesis may constitute the multiple and complementary mechanisms underlying HBOT-induced neuroprotection.^[4]

CONTRAINDICATIONS:

The contraindication to HBOT may vary according to indication (absolute or relative), clinical settings (emergency or ambulatory) and hyperbaric centre capability (staff, equipments, location). First contraindication is inadequate hyperbaric oxygen facilities equipment, technical competence and staff and personal skill such that any potential accident, dearrangement or problem will not be likely to interfere with the decision to accept a patient with an indication for HBOT. Facility must be located, equipped and staffed in order to guarantee the community of the treatment chain. To expose a patient safety for two main reasons: to expose a patient to highly predictable risk would be considered unethical even in absence of any published evidence, accident and adverse effects are grossly under-report in the medical literature.^[5]

Absolute contraindication because of the risk for severely disabling oxygen toxicity: Concomitant treatment with doxorubicin and Concomitant or recent treatment with bleomycin. Absolute contraindication because of an unacceptable risk for endangering patient safety: treatment with HBOT only if the medical and nursing staff and the chamber equipment are fit to care for the patient.

Relative contraindications because of the increased risk for barotraumas, increased risk for oxygen toxicity and increased risk related to the high oxygen pressure environment, risk of unacceptable risks due to psychological and behavioural issues.

PRECAUTIONS IN SELECTION OF PATIENTS FOR HBOT:

The patient needs to be screen carefully for following:

· Chest X-Ray

· Pulmonary function test

· Examination of the ear drums.

· Large skull defect with scalp flaps

· Implanted devices such as cardiac pacemakers.

COMPLICATIONS:

Pulmonary complication such as acute pulmonary oxygen toxicity due to breathing of ophthalmic complications such as myopia which is reversible complication and cataract due to long term exposure to HBOT. Increase free radicals may play a role in pathogenesis. Pulmonary barotraumas is quite low and most series with treatments under 2ATA but over inflation with pressure may lead to lung rupture. Pneumothorax in patient under HBO treatment is a serious complication which causes tracheal shifting asymmetrical movements of chest. In neuro complication oxygen induced seizures when the duration of treatment was kept low and patient mask need to be removed if patient was in multiplace chamber. Other complication such as decompressive sickness and genetic effects can damage the DNA to human beings. Claustrophobia and anxiety reaction in patient undergoing HBO therapy are mostly seen in patient treated in Monoplace chamber.⁵Cataract in HBOT leads to an increase in pO₂ and concentration of ROS in blood and tissues, including the lens stroma of the cornea, where it plays a role in cataractogenesis.^[6]

The development of cataracts in humans has been reported only after prolonged exposure to hyperbaric oxygen, usually 150 treatments or more.^[7,8]

CONCLUSION:

HBOT is an established therapeutic approach in much acute, life-threatening condition also has been submitted to scrutinizing evaluation for new indications. Mechanisms of HBOT induced beneficiary effects are under intense investigation and understanding promise HBO2 with low unwanted side effects when utilization in well design on.

REFERENCES:

1. M.Daniel. Handbook on hyperbaric medicine. Springer sciences and business media. 2006; pg.1-2.

2. Drenjancevic. Hyperbaric oxygen treatment in research and clinical practice: mechanism of action in focus. British library cataloguing in publication.201; pg.3-4.

3. Kewal K. Jain. Textbook of hyperbaric medicine.2016; pg.79-80.

4. Blaise C, Nadia S, Bella G, Madeline S, Justin C, You sung et.al.an extra breath of fresh air: Hyperbaric oxygenation as stroke therapeutic. Biomolecules. 2020 Sep; 10(9): 1279.

5. Tom S, Neuman, Stephen, R. Thom. Physiology and medicine of hyperbaric oxygen therapy. Elsevier publication; 200:588-95.

6. Michael J, Steven H, Rose, Denise J, Wedel, C. Thomas Wass, Barry A Harrison et.al. Faust’s Anesthesiology review. Elsevier health sciences publication. 2014:224.

7. McMonnies CW. Hyperbaric oxygen therapy and the possibility of ocular complications or contradictions. Clin Exp Optom 2015; 98:122–125.

Received on 10.11.2020 Modified on 29.11.2020

Int. J. of Advances in Nur. Management. 2021; 9(1):99-101.

DOI: 10.5958/2454-2652.2021.00025.1