decompression illness is caused by intravascular or extravascular gas bubble formation following rapid reduction in environmental pressure as seen with diving accidents . it comprises two different pathophysiological syndromes : decompression sickness and arterial air embolism caused by pulmonary barotrauma . decompression sickness can occur when a diver 's time at depth leads to supersaturation of dissolved gases ( usually nitrogen ) and bubble formation during decompression . when the rate of ambient pressure reduction exceeds the rate of inert gas washout from tissue , formation of gas bubbles in the extravascular tissue may lead to tissue injury , vessel obstruction and organ dysfunction . arterial air embolism occurs when expanding gas ruptures alveolar capillaries ( pulmonary barotrauma ) and enters the arterial circulation as a result of rapid decompression . this is typically seen with rapid uncontrolled ascents especially in the setting of breath - holding or the presence of an underlying lung disease ( with reduced compliance ) . typical manifestations include cerebral symptoms ( weakness , numbness , confusion or unconsciousness , seizure , visual disturbances , headaches and vertigo ) when bubbles rupture into vessels , or respiratory symptoms ( pleuritic chest pain due to pneumothorax or pneumomediastinum ) when bubbles rupture into pleural spaces . however , other sites including muscles , mesenteric circulation , cardiovascular system and , as shown in the following case , the kidneys may also be involved . we report the first case of acute kidney injury caused by arterial air embolism injury in a 27-year - old caucasian recreational diver following three rapid ascents . he was spear fishing on surface supply hookah at a depth of 15 metres for around 15 min when strong currents took him up to the surface whilst he was holding his breath attempting to reload his speargun . he had another two attempts to rescue his gear from the seafloor , but he was taken up by the swell each time . during the third ascent he became confused and when reaching the surface , his vision became blurred and he was unable to move his limbs . on arrival at the local hospital he was normotensive and his neurological symptoms resolved within a few hours . due to initial pleuritic chest pain , a computer tomography was performed which showed normal lung parenchyma and no evidence of pneumothorax or pneumomediastinum . nine hours after the incident , he developed diffuse abdominal pain with an initial lactate 10.8 mmol / l . further imaging to look for ischaemic gut was not performed as he responded well to initial therapy consisting of 100% oxygen , analgesia with paracetamol and fentanyl ( two doses , each 25 g intravenously ) and intravenous hydration and his lactate level returned to normal within a few hours . due to rapidly evolving acute kidney injury , he was transferred to a tertiary hospital for hyperbaric therapy on day 2 post - diving accident ( initial creatinine 120 mol / l , 987 mol / l on day 2 and peak at 1210 mol / l on day 4 ) . the diagnosis of ischaemic - induced acute tubular necrosis ( atn ) was supported by a high fractional urinary sodium excretion of 5.5% , elevated lactate dehydrogenase [ 486u / l ( 125250 ) ] , normal urine sediment and urinary tract ultrasound and a mag3 scan in keeping with atn ( figure  1 ) . the absence of myoglobinuria and only moderately elevated creatine kinase [ maximum 893u / l ( 30170 ) ] made rhabdomyoloysis - induced atn unlikely . he received supportive care with intravenous hydration , sodium bicarbonate combined with a total of seven sessions of hbo and recovered fully without needing dialysis ( figure  2 ) . 1.tc-99m-mag3 scan performed on day 4 post - diving accident : the first two panels show the perfusion of both kidneys over 32 s ( 2 s / frame ) and the third panel shows tracer concentration ( reflecting renal function ) over 16 min ( 2 min / frame ) . the top graph ( renogram ) shows normal perfusion of the left and right kidney and the bottom graph illustrates tracer retention in the left and right kidney in keeping with acute tubular necrosis . 2.time line of creatinine ( mol / l ) and clinical symptoms . tc-99m - mag3 scan performed on day 4 post - diving accident : the first two panels show the perfusion of both kidneys over 32 s ( 2 s / frame ) and the third panel shows tracer concentration ( reflecting renal function ) over 16 min ( 2 min / frame ) . the top graph ( renogram ) shows normal perfusion of the left and right kidney and the bottom graph illustrates tracer retention in the left and right kidney in keeping with acute tubular necrosis . decompression illness due to arterial air embolism following rapid ascent is a serious diving complication and can present with multi - organ involvement including the kidneys as demonstrated in this case . upon rescue onto the support boat the patient was positioned supine whilst the boat was rocking in the waves , which may have contributed to embolization at multiple sites , including the central nervous system , the mesenteric circulation , as suggested by elevated lactate and abdominal pain and the kidneys . the diagnosis of decompression illness is made on clinical grounds since gas bubbles are rarely detectable on imaging . the most common symptoms of decompression sickness are localized pain , numbness / paresthesia and muscular weakness , typically presenting within the first 24 h , whereas symptoms of air embolism from pulmonary barotrauma occur immediately upon ascent [ 4 , 5 ] . although no diagnostic blood test exists for air embolism , widespread air embolization has been reported to result in elevated serum creatine kinase of up to 900 u / l , as was the case in our patient . the distinction between pulmonary barotrauma and decompression sickness is sometimes difficult and generally unnecessary as recompression is the treatment of choice for both . when hyperbaric therapy is not readily available , the best first aid treatment comprises administration of 100% oxygen and supportive care . however , early transfer to a hyperbaric treatment unit is important as symptoms may evolve over time as shown in our patient . hyperbaric oxygen ( hbo ) leads to quick elimination of gas bubbles by reducing bubble size via increased pressure ( boyle 's law ) , increasing the inert gas partial pressure gradients between tissue and alveolar gas ( increased nitrogen washout ) and also oxygenates ischaemic tissue and exerts an anti - inflammatory effect [ 1 , 7 , 8 ] . the addition of non - steroidal anti - inflammatory drugs such as tenoxicam may decrease the number of hbo sessions required as shown in a randomized trial , but their use does no longer make part of the routine treatment and was not an option for our patient in the setting of acute kidney injury . hbo results in complete resolution of symptoms in most cases , whereas mild residual symptoms may persist in a few and serious complications in a minority of cases . the primary goal , however , remains the prevention of pulmonary barotrauma , a potentially fatal complication of diving . divers should be screened during dive medical for conditions predisposing to barotrauma ( airway obstruction , bullae , reduced lung compliance ) and diving courses emphasize the importance of controlled ascent and avoiding breath - holding . a.v . : patient diagnosis and management , literature search and writing of the paper ; j.j . : patient management ; a.w . : patient management ; literature search and writing of the paper ; n.b . : patient management ; literature search and writing of the paper ; and p.f . : management , literature search and writing of the paper .
decompression illness is a rare but serious complication of diving caused by intravascular or extravascular gas bubble formation . 
 we report the first case of acute kidney injury in a 27-year - old diver following three rapid ascents . 
 he presented with transient neurological symptoms and abdominal pain followed by rapidly progressive acute kidney injury ( creatinine peak 1210 
 mol / l ) due to arterial air emboli . 
 he received supportive care and 100% oxygen followed by hyperbaric therapy and recovered fully . 
 arterial air emboli caused by rapid decompression can affect multiple organs including the kidneys . 
 early transfer to a hyperbaric unit is important as complications may present delayed .