Complications of Hyperbaric Oxygen Therapy พญ. อัจฉมาพร สาลี Complications of Hyperbaric Oxygen Therapy O Related to effects of pressure on enclosed gas spaces O Related to oxygen toxicity O Psychogenic effect O Others Complications of Hyperbaric Oxygen Therapy O Related to effects of pressure on enclosed gas spaces (Barotrauma) O Ear barotrauma O Sinus barotrauma O Pulmonary barotrauma O Other barotrauma O Related to oxygen toxicity O Psychogenic effects O Others Barotrauma O Although human tissues may support great pressure, tissue injury can occur O resulting from failure of gas-filled space to equalize its internal pressure with ambient pressure changes O Boyle’s Law Barotrauma O Diving activities, compressed-air work, aviation and hyperbaric therapy O Injury is most likely when O Pressure-volume changes are great O Onset is rapid – as occurs during initial parts of pressurization or descent from atmospheric pressure Barotrauma O Two conditions must be present for barotrauma to occur O Change in ambient pressure O Transfer of pressure to a non- or partially collapsible airspace Barotrauma O In particular may affect middle ear and sinuses; lung; intestines; teeth; eye, particularly when surrounded by air space like a face mask; and other physiological or pathological gas spaces Ear barotrauma External ear barotrauma External ear barotrauma O External ear canal O 3.5 cm long and 1 cm wide O Barotrauma of canal and eardrum are possible O because ambient and outer ear pressures can not be equilibrated O Usually external ear is filled with water or air at ambient pressure O With blocked canal (e.g., by an ear plug or wax) pressure changes during descent and ascent O possible injury of epithelial lining of the external meatus and TM, with edema, hemorrhage and rarely perforation of eardrum External ear barotrauma O Other causes include external ear infection, exostoses; foreign bodies; and tight-fitting neoprene diving hoods O Pain is made worse by clearing ears O mild conductive deafness and vertigo may be present until pressure is relieved O Otoscopy reveals an ear canal that is swollen with hemorrhagic blistering; bleeding is possible Middle ear barotrauma Middle ear barotrauma O Middle ear cavity communicates with nasopharynx through Eustachian Tube (ET) – a 4 cm long tube O Under normal conditions tube is opened by chewing, swallowing or yawning due to action of controlling muscles O Allows equalization to occur between middle ear and nasopharyngeal air pressure Middle ear barotrauma O Closure of ET is passive process and it is collapsed in its natural state O Passive escape of gas occurs when middle ear pressure is around 4 cm H2O higher than ambient pressure Middle ear barotrauma O Rarely spontaneous equalization during increasing ambient pressure and this is why barotitis media may occur O Most common diving and hyperbaric medical complication Middle ear barotrauma O Otological barotrauma of descent is characterized by O initial sensation of ear blockage O followed by sharp pain O If swelling, bleeding or perforation O occurs this may be accompanied by a conducting hearing loss, mild tinnitus and vertigo Middle ear barotrauma 6 grade severity classification by Edmonds O Grade 0 - Symptoms without otoscopic signs O Grade 1 - Diffuse redness and retraction of TM O Grade 2 - Grade 1 changes plus petechial hemorrhage TM O Grade 3 - Grade 1 changes plus confluent /plaque hemorrhage in TM O Grade 4 - Dark and slightly bulging TM : free blood or fluid in middle ear O Grade 5 - TM perforation with possible blood in our outside ear canal Middle ear barotrauma O Treatment depends on degree of barotrauma O Avoided exposure to pressure O Recovery usually occurs over 3 to 14 days O Topical and systemic nasal decongestants O Pain relief O Rupture TM systemic broad spectrum antibiotic O Large perforations, especially those associated with deafness or tinnitus referred to ENT Middle ear barotrauma O Middle ear barotrauma of ascent O for ET dysfunction to cause air trapping O TM bulging outwards O May cause asymmetrical stimulation of the vestibular apparatus with alternobaric vertigo of ascent (called Lündgren Syndrome) O Self- limiting form of transient dizziness usually occurs during ascent O It is less common during descent O Although transient, vertigo, disorientation and nausea – usually lasting less than 10 minutes – may present serious problems for divers, particularly at depth Middle ear barotrauma O Alternobaric facial paralysis O transient unilateral facial paralysis in association with ipsilateral middle ear overpressure O Mechanism : facial nerve neuropraxia O Full facial nerve function usually returns to normal within 2 hours of returning to atmospheric pressure O Diving is not recommended O Myringotomy is advised Inner ear barotrauma Inner ear barotrauma O Using forceful Valsalva’s maneuvers O May elevate intracranial and inner ear hydrostatic pressure sufficiently to cause rupture of inner ear structures O Basement membrane rupture, or round and/or oval windows may be involved Inner ear barotrauma O Rupture of round window leads to a perilymph leak into middle ear perilymph fistula O Extremely rare in hyperbaric medicine practice O History of O serious vertigo O intense tinnitus O sensation of fullness in ear O sensory-neural hearing loss O nausea and vomiting O positive Romberg sign O nystagmus Inner ear barotrauma O Treatment : O Bed rest. with elevated reduce ICP O Evaluated with audiogram, electronystagmogram and be submitted to complete otorhinolaryngological and neurological evaluation O Hyperbaric exposures should be avoided until complete clinical recovery O if it is essential to continue HBO, myringotomy Sinus barotrauma Sinus barotrauma O Related to inadequate pressure equilibration in gas volumes of sinus cavities O Ostial obstruction with inadequate gas passage between nasal cavity and sinuses Sinus barotrauma O Cause of obstruction : mucus, nasal polyps, congestion of nasal mucosa, foreign bodies, nasal structural deformities or mass lesions, O sinus barotrauma of descent (sinus squeeze) or ascent (reverse sinus squeeze) O frontal and maxillary sinuses being the most commonly affected Sinus barotrauma O Hydrostatic pressure is transferred throughout body O Higher than pressure within gas space O Relative vacuum phenomenon occurs with blood vessel dilatation O Possible rupture and hemorrhage in sinus space Sinus barotrauma O Main symptom is pain, which may persist for several hours O Associated with bloody nasal discharge O Paresthesia of cheek or forehead may occur with maxillary or frontal sinus squeeze respectively O Due to compression of branches of fifth cranial nerve O Pain may be referred to occipital region with sphenoid sinus barotrauma Sinus barotrauma O Function. of pressure O Valsalva’s maneuvers,over-pressurized sinus cavity may lead to migration of air to the cranium or infra-orbital plate fractures with ophthalmic involvement and – rarely – pneumocephalus O Meningitis and blindness rare but have been reported O Again there are no known references to these severe complications during HBO therapy Pulmonary barotrauma Pulmonary barotrauma O Pulmonary barotrauma results from pulmonary overexpansion in response to a reduction in ambient pressure O Intra and extravascular intrapulmonary gas migration follow with various potential complications Pulmonary barotrauma O Pulmonary overpressure is most frequent cause of arterial gas embolism O Relatively common in diving (approximately 10% of diving accidents) O Very rare in hyperbaric medicine practice O Causes include rapid decompression and high positive pressure ventilation Pulmonary barotrauma O Arterial gas embolism O Pneumothorax O Pneumo-mediastinum O Subcutaneous emphysema Pulmonary barotrauma O Gas may exert local pressure effects or cause cerebral and coronary arterial gas embolism(AGE) O most dangerous complication Pulmonary barotrauma Risk of barotrauma O during decompression O decreased pulmonary compliance O previous spontaneous pneumothorax O acute lower respiratory infection O Atelectasis O bullous emphysema O pulmonary cysts O blunt chest trauma O sub-pleural blebs O pulmonary fibrosis O COPD with air trapping O Many of these conditions may not be adequately excluded by CXR Pulmonary barotrauma O Management, depending on severity O includes: O 100% O2 by oronasal mask O Emergency drainage of a tension pneumothorax by needdle thoracostomy O Definitive management of intrapleural gas or blood is ICD O If HBO is required, Heimlich one-way valve should be connected to drainage system O If recompression is not required regular underwater drainage is appropriate O Pericardial drainage for gas tamponade with needle pericardiocentesis Other barotrauma Other barotrauma Barodontalgia (Tooth or dental barotrauma) O characterized by pain or injury during changes in ambient pressure O mechanism involved may be related to expansion of trapped air in a cavity underneath crown of tooth with pain receptor activation O stimulation of nerve endings in chronic inflamed pulp O stimulation of maxillary sinus pain receptors. Other barotrauma Gastrointestinal Excessive swallowing of gas (i.e., aerophagia) during decompression O Rare, occur due to expansion of air in stomach and bowel, causing abdominal distension and colicky pain. Other barotrauma ocular barotrauma O Hx of ophthalmic surgical procedures O have gas in anterior chamber or vitreous cavity O This may be affected by pressure changes with resulting barotrauma including O retinal, uveal or vitreous