Decompression Sickness Kun-Lun Huang National Defense Medical Center Undersea and Hyperbaric Medical Institute Tri-Service General Hospital Department of Undersea and Hyperbaric Medicine
Hazard Diving Environment 10 m 50 m 90 m 180 m O 2 O 2 toxicity Air N 2 narcosis Dark Cold Air O 2 toxicity N 2 narcosis CO 2 retention Predators Heliox HPNS DCS Air embolism 686 m 1981 Convulsion
Case 1 M/25, professional diving photographer Dove to 30 meters for 40 min twice a day Pain in the left elbow 1 hour after surfacing Recompression therapy Went home right after treatment without any residual symptom
Case 2 M/42, recreational diver Dove to 50 meters for 20 min and surfaced without stopping because out of air supply Paraplegia 30 min after surfacing Recompression therapy Stayed in the hospital for one month and discharged without sequelae
Decompression Sickness A disease caused by the formation of gas bubbles with tissues, which is due to supersaturation of gas dissolved in the body fluid during reduction of ambient pressure
N 2 N 2 N 2 N 2 N 2 N 2
Gas Exchange N 2 N 2 CO 2 O 2 N 2
Gas Uptake and Elimination Pressure, ATA 4 3.5 3 2.5 2 Hydrostatic pressure Airway N 2 partial pressure Tissue N 2 partial pressure 1.5 1 P t = P 0 + ( P a -P 0 ) x ( 1 - e -kt ) 0 5 10 15 20 25 30 35 40 45 50 55 60 Time
Gas Diffusion in the Lungs
Perfusion-Limited Gas Transport
Gas Uptake and Elimination P t = P 0 + ( P a -P 0 ) x ( 1 - e -kt )
Gas Uptake and Elimination Pressure, ATA 4 3.5 3 2.5 2 Hydrostatic pressure Airway N 2 partial pressure Tissue N 2 partial pressure P t = P 0 + ( P a -P 0 ) e -kt 1.5 1 0 5 10 15 20 25 30 35 40 45 50 55 60 Time
Blood Flow and Fat Content Tissue Blood Flow ml/min/100 g Fat Content %dry weight Adipose 2.6 85 Spinal cord White 10-15 >75 Gray 50-70 30 Straited m Rest 3-5 22 Exercise 50-75 Kidney 508 24 P t = P 0 + ( P a -P 0 ) e -kt K = V Q S 1 v = =1/τ S 2 V
Gas Uptake and Elimination 3 Fast tissue Intermediate Intermediate Slow tissue Pressure, ATA 2 Supersaturation 1 0 5 10 15 20 25 30 35 40 45 50 55 60 Time, min
Gas Bubble and Tissue Injury Muth & Shank, NEJM 342:476, 2000
Air Bubble-induced Tissue Injury Possible mechanism Primary effects Bubble Secondary effects Disruption Obstruction Coagulation factors Protein denaturation Complement Kinins Ischemia & Hypoxia Platelet Oxygen radicals Neutrophil Arachidonic metabolites Proteolytic enzymes Tissue damage
Symptoms of DCS Itching & Crutis Marmorata Bends Joint Pain & Rhabdomyelysis Skin Muscle Chokes Lung Inner ear Vertigo Cardiovascular Shock Spinal cord Paralysis Death
Acute DCS Type I decompression sickness Musculoskeletal pain Skin manifestations Constitutional symptoms Type II decompression sickness Lung: gas embolism or chokes CNS: paraplegia or stroke Vestibular system: vertigo Cardiovascular system: shock
Diagnosis of Acute DCS No objective laboratory examination available for definite diagnosis Diving history Working (diving) pattern Diving depth, bottom time, ascending, and repetition Onset of symptoms Empiric recompression as a proof of diagnosis
Occupations and DCS Diving fishermen Recreational divers Military divers Tunnel workers Underwater construction crews Fighter pilots
Spencer s s Bubble Grading
Spectral Analysis of Bubble Signals
Treatment of DCS Stablizing vital signs Recompression Adjunctive treatments Analgesics NSAIDs Corticosteroids Anticoagulants
Boyle s Law
USN Treatment Table 6A
USN Treatment Table 6A 180 160 140 Compressed air Hyperbaric oxygen Depth, ft 120 100 80 60 40 20 0 0 50 100 150 200 250 300 Time, min
Case 3 M/33, diving fisherman Type II DCS with CNS symptoms of confusion Treated with USN Table 6A without O 2 breathing Delirium and crutis marmorata after surfacing Coma and profound chock during surfacing in the second course of Table 6A treatment Endotracheal intubation and sedation and then recompression therapy Stayed in the hospital for one week
Diffusion of Gases (distance)
Gas Exchange N 2 =79% N 2 =79% P AN2 =1800 mmhg P N2 =2000 mmhg
Gas Exchange O 2 =100% O 2 =100% P AN2 = 0 mmhg P N2 =2000 mmhg
Gas Uptake and Elimination Pressure, ATA 3 2 Fast tissue Intermediate Intermediate Slow tissue 1 0 5 10 15 20 25 30 35 40 45 50 55 60 Time, min
USN Treatment Table 6A
USN Treatment Table 4
USN Treatment Table 5
Case 4 M/32, recreational diver Dove to 30 meters for 40 min four times a day Epigastric fullness a few minutes after surfacing Limb weakness 5 hours later Recompression therapy Progression to paraplegia and urinary retention during HBO 2 therapy Combined high dose corticosteroid and HBO 2 Stayed in the hospital for 2 weeks and was transferred for further rehabilitation
Air Bubble-induced Tissue Injury Possible mechanism Primary effects Bubble Secondary effects Disruption Obstruction Coagulation factors Protein denaturation Complement Kinins Ischemia & Hypoxia Platelet Oxygen radicals Neutrophil Arachidonic metabolites Proteolytic enzymes Tissue damage
Treatment of DCS Stablizing vital signs Recompression Adjunctive treatments Analgesics NSAIDs Corticosteroids Anticoagulants
Case 5 M/56, well maker Dove for making deep well (20 to 30 meters) in the construction area for 20 + years Denied having symptoms of severe DCS Painful disability of bilateral hips for years Total hip replacement
Chronic DCS Dysbaric osteonecrosis CNS degeneration
Delayed Treatment of DCS in USA 12-24 hr 4-12 hr > 24 hr < 4 hr Diving Alert Network (DAN)
Residual Symptoms > 12 hr > 12 hr 4-12 hr < 4 hr 4-12 hr < 4 hr Type I DCS Type II DCS Diving Alert Network (DAN)
Prevention from DCS Knowing your limitations Obeying the rules of diving Understanding effects of exercise Avoiding fly after diving Knowing individual susceptibility Obesity Sex De-acclimatization
Incidence of DCS 50 40 30 20 10 0 Male Female
Body Compositions 50 40 Male Femal 30 20 10 0 Adipose Muscle
Body Fat and DCS 23 22 21 20 19 18 17 16 15 No DCS Hx of DCS DCS
USN Air Decompression
USN Air Decompression
No Decompression Limits
Diving Pattern of Well Diver 0 Depth, m 4 8 12 16 0 100 200 300 400 500 Time, min
Diving Pattern of Well Diver 0 Depth, m 2 4 6 8 10 0 100 200 300 400 500 Time, min
No Decompression Limits
Surface Interval in Repetitive Dives
Residual Nitrogen in Repetitive Dives
USN Air Decompression
Surface Interval in Repetitive Dives
Residual Nitrogen in Repetitive Dives
USN Air Decompression
Residual Nitrogen Time (Equivalent Single Diving Time)
Thank You
Record of Free Diving Depth