Hyperbaric Oxygen Therapy(HBOT)

Definition Medical use of oxygen at a Medical use of oxygen at a higher than atmospheric pressure (One Atatospheric Pressure Absolute=APA= 760 mm Hg)

Oxygen concentration of blood (in ml O 2 — 100 ml -1 blood) Oxygen content Dissolved Oxygen

O 2 dissociation curve

History 1662

Fontaine’s mobile operating room 1879

Cunningham’s chamber in 1921

Steel Ball Hospital 1928

Today

Primary Effects  Direct Pressure Effect(Decrease gas bubble size)  Hyper-oxygenation – fold increase in plasma oxygen, ~ mmHg 2-4 fold increase in oxygen diffusion capacity from capillaries.

Boyle’s Law Henry’s Law

Secondary Effects Antimicrobial Effect Vasoconstriction/Decreased Edema Angiogenesis/Wound Healing Enhanced host immune function

Antimicrobial Effect Bacteriostatic Bactericidal Antibiotic Enhancement

INDICATIONS 1.Air or Gas Embolism. 2. Carbon Monoxide Poisoning/Cyanide Poisoning. 3. Clostridial Myositis and Myonecrosis (Gas Gangrene) 4. Crush Injury, Compartment Syndrome and other Acute TraumaticIschemias. 5. Decompression Sickness. 6. Hypoperfusion syndromes(Fetal alcohol syndrome Cerebral Palsy, Closed head injury,Stroke )

Carbon monoxide poisoning

Pathophysiology CO is colourless, odourless, nonirritant toxic gas CO toxicity due to  Cellular hypoxia  Direct cellular injury Cellular hypoxia  CO competes with O2 for binding to Hb  Affinity of Hb for CO x > affinity for O2  O2-Hb dissociation curve shift to the left  Impaired tissue release of O2 and cellular hypoxia

Treatment High-flow, FiO2 ~100%, normobaric O2 O2 shortens the half life of COHb  21% O2 = 4-6 hours  100% O2 = minutes  100% O2 2.5atm = minutes Continue O2 until COHb normal Beware concomitant smoke inhalation and burn injury Normobaric v Hyperbaric O2 therapy  HBO hastens resolution of acute symptoms  Unclear evidence for effect of HBO on late complications and mortality

Indications for Hyperbaric-Oxygen Therapy in Patients with Carbon Monoxide Poisoning

Contraindications 0f HBO

Absolute HBO Contraindications Untreated Pneumothorax Severe Acute Bronchospasm. Current Disulfiram Recent Bleomycin Use. Current Doxorubicin (Adriamycin).

Relative HBO Contraindications Upper Respiratory Infections COPD Seizure Disorder Fever Prior Ear Surgery History Spontaneous Pneumothorax Pregnancy Optic Neuritis

Uncontrolled Hypertension Untreated Dental Problems History Chest Surgery/Trauma Claustrophobia Decompensated Congestive Heart Failure Congenital Spherocytosis

Complications Barotrauma Oxygen toxicity Others

Organs Affected by Barotrauma Sinuses Middle ear External ear Inner ear GI tract Teeth Lung Congestion and/or occlusion Eustachian tube occluded Failure to equalize pressure within middle ear space Wax build-up or ear plugs occlude canal Oval or round window rupture Gas in bowels, distention on ascent Infected or restored teeth (may harbor gas)

Potential Complications of HBO Middle Ear Barotrauma – the most common with reported incidence rates of 2% - 82%.

Potential Complications of HBO Sinus Barotrauma – 2 nd most common complication. Presentation – pain and epistaxis Frontal Sinus Squeeze – frontal pain Maxillary Sinus Squeeze – tooth ache Sphenoid Sinus Squeeze – occiput or vertex pain

Claustrophobia Reversible myopia Seizures (0.01 – 0.03%) Oxygen Toxicity Potential Complications of HBO