DECOMPRESSION SICKNESS AND GAS EMBOLISM

DECOMPRESSION SICKNESS AND GAS EMBOLISMMohammad Guritno SURYOKUSUMOKetua Minatan Kedokteran HiperbarikProgram Pascasarjana Fakultas KedokteranUnversitas Indonesia, Jakartaemail: mguritno@yahoo.com

DECOMPRESSION SICKNESSDecompression sickness (DCS) refers to the clinical syndrome of neurological deficits, pain, or other clinical disorders resulting from the body tissues being supersaturated with inert gas after a reduction in the ambient pressure.ARTERIAL GAS EMBOLISMArterial Gas Embolism (AGE) refers to gas bubbles in the systemic arterial system resulting from pulmonary barotrauma, iatrogenic entry of gas into the arterial system, or arterialized venous gas emboli.2Terminology and ClassificationThe differentiation between illness and sicknessDecompression iIlness (DCI) or Dysbaric illness (DI) is an inclusive term that encompasses either or both DCS and AGE.Various clinical terms have emerged in an ongoing effort to describe and classify DI.Clinical syndromes (e.g., the bends, chokes and staggers)A presumptive assignment of etiology and severity (e.g., type I decompression sickness and arterial gas embolism)The systematic capture of descriptive clinical and causal factors associated with the condition (e.g., decompression illness or dysbarism, and gas bubble illness).

Dilemma & Future Classification SystemsThe present trend is towards developing clearly defined case definitions for DCS, AGE and combined forms.The dilemma in developing these is that there is disparity between epidemiological and clinical objectives.The ECHM has recommended the development and acceptance of such an epidemiological classification system which will allow multi-center, multinational, retrospective analyses derived from broad-based classifications that include the type of diving, chronological data, clinical manifestations and outcome of a two-year follow up for prognostic purposes.Classification of DIThe traditional or Golding ClassificationThe descriptive or Francis & Smith Classification3. The ICD-10 ClassificationModified Golding Classification for DIArterial Gas EmbolismDecompression Sickness 1. Type I : Musculoskeletal Pain; Skin; Lymphatic; Extreme Fatigue; Peripheral Nervous Symptoms 2. Type II : Neurologic; Cardiorespiratory; Audio-vestibular; Shock 3. Type III : Combined Decompression Sickness and Arterial Gas EmbolismTable The Francis & Smith Classification for Dysbaric IllnessEvolutiono Spontaneously Recovery (Clinical improvement is evident)o Static (No change in clinical condition) Relapsing (Relapsing symptoms after initial recovery)Progressive (Increasing number or severity of signs)Organ System:o Neurologicalo Cardiopulmonaryo Limb pain exclusivelyo Skino Lymphatic VestibularTable The Francis & Smith Classification for Dysbaric IllnessTime of onset:Time before surfacingTime after surfacing (or estimate)

Gas Burdeno Low (e.g., within NDL)o Medium (e.g., Decompression Dive) High (e.g., Violation of Dive Table)

Evidence of Barotraumao Pulmonary (Yes / No)o EarsSinuses

Other Comments

The ICD-10 ClassificationThe ICD-10 codes most frequently used are:T70 (Effects of air pressure and water pressure)T70.0 (Otitic barotrauma)T70.1 (Sinus barotrauma)T70.3 (Caissons disease)T70.4 (Effects of high-pressure fluids)T70.8 (Other effects of air pressure and water pressure)T79.0 (Traumatic air embolism)T79.7 (Traumatic subcutaneous emphysema)M90.3 (Osteonecrosis in caisson disease T70.3+)9Clinical Setting Diving2. Flying3. HBOTPATHOGENESIS OF DCSDenaturation of Plasma ProteinsEndothelial DamageInteraction of Bubbles with the Blood Coagulation SystemGeneral Aspect :Most of the clinical manifestations of DCS are thought to result from tissue distortion of vascular obstruction produced by bubblesPresenting SymptomsTypeCases (%)Local PainArmLeg

Vertigo (staggers)Paralysis Shortness of breath (chokes)Extreme fatigue with painCollapse + unconsciousnessType I

Type 2893070

5.32.31.61.30.5Frequency of Various Symptoms of DCS

Classification of initial and of all eventual manifestations of decompression illness in 2346 recreational diving accidents reported to the Divers Alert Network from 1998 to 2004 Classification of initial and of all eventual manifestations of decompression illness in 2346 recreational diving accidents reported to the Divers Alert Network from 1998 to 2004 Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E MoonElliott DH and Moon RE. Manifestations of the decompression disorders. In: The Physiology and Medicine of Diving (4th ed.), edited by Bennett PB and Elliott DH. London: W. B. Saunders, 1993, p. 481505.

The time of onset of symptoms after surfacing30 % occurred < 30 minutes85 % occurred < 1 hour95 % occurred < 3 hours1 % Delayed more than 6 hoursPredisposing FactorsExerciseInjuryColdObesityIncreased Fractional Concentration of CO2 to inspred GasAgeIngestion of AlcoholDehydrationFatigue

Treatment of DCSPre-RecompressionOxygen 15 L/M with reservoir mask or demand valvePatient in supine position (not head down)Continuous monitoringAir transport : As low as safely possible. Preferably lower than 1000 ftPressurize aircraft cabin to 1 ATA if possibleConsider Emergency Evacuation Hyperbaric StretcherRecompress even if signs/symptoms resolve prior to recompressionTreatment of DCSInitial Recompression for DCS

The USN Diving Manual treatment algorithms remain the gold standard for initial recompression of diving-related DCI. The use of alternate tables should be reserved for trained personnel at facilities with the expertise and hardware to deal with untoward/unexpected responses to therapy.

Surface oxygen is not a substitute for hyperbaric therapy in diving related DCI. However, surface oxygen alone can be considered if symptoms are mild and have been stable for 24 hours, neurological examination is normal, and evacuation of the patient cannot readily be achieved or is associated with some risk (3).Treatment of DCSType I Treatment Table 5 (TT5)Musculoskeletal painSkin bendsLymphatic bends

Type II Treatment Table 6 (TT6)Includes all other manifestations of DCSRecompress to 60 FSW on 100% O2 and begin TT6Diving Medical Officer (DMO) has option to go to 165 early ifpatient has unsatisfactory response at 60 FSW

*Note: Severe Type II signs/symptoms warrant full extensions of 60 FSW oxygen breathing periods even if S/S resolve during the first oxygen breathing period

Deep Uncontrolled Ascents (Treatment Table 8 (TT8) 225 FSW table for treating deep, uncontrolled ascents when more than 60 minutes of decompression have been missed.Treatment of DCSPersistent Symptoms at 60 FSWExtend TT6 for two 25-minute periods at 60 FSWExtend TT6 for two 75-minute periods at 30 FSWDMO may recommend customized treatmentStay at 60 FSW for 12 hours or longer come out on TT7Recurrence of Serious Symptoms during DecompressionIf shallower than 60 FSW go to 60 FSWIf deeper than 60 FSW go to 165 FSWTreatment of DCSPersistent Symptoms at 60 FSWExtend TT6 for two 25-minute periods at 60 FSWExtend TT6 for two 75-minute periods at 30 FSWDMO may recommend customized treatmentStay at 60 FSW for 12 hours or longer come out on TT7Recurrence of Serious Symptoms during DecompressionIf shallower than 60 FSW go to 60 FSWIf deeper than 60 FSW go to 165 FSWTreatment of DCSIn-Water RecompressionOnly when:No recompression facility on siteSignificant signs/symptomsNo prospect of reaching chamber in 12-24 hrsNo improvement after 30 min of 100% oxygen on surfaceThermal conditions are favorableNot for unconsciousness, paralysis, respiratory distress, or shockKeep these individuals on the surface with 100% O2Treatment of DCSIn-Water RecompressionOnly when:In-Water Recompression with oxygen preferredPurge rebreather 3 times with oxygen30 FSW with stand-by diver60 min at rest for Type 190 min at rest for Type II20 FSW for 60 min10 FSW for 60 min100% O2 for additional 3 hours on the surfaceTreatment of DCSIn-Water Recompression with air (if no oxygen available)Follow TT1AFull face mask or surface-supplied helmet preferredSCUBA used only as last resortStand-by diver required

* Note: In divers with severe Type II symptoms or symptoms of arterial gas embolism (e.g. unconsciousness, paralysis, vertigo, respiratory distress (chokes), shock, etc), the risk of increased harm to the diver from in-water recompression probably outweighs any anticipated benefit.

DCS PREVENTIONDiver SelectionScreening for Patent Foramen Ovale (PFO)History of DCS Disqualifying for diving dutyDeselection of divers for repeated episodes of DCS Not recommended

2.Pre-Dive DCS PreventionPre-dive exercise, No recommendationTable modifications based on water temp No recommendationHydration (in warm water diving)Dive depth limits: For SCUBA dives maximum depth of 130 ft (on-site chamber recommended for military diving if dive depth is greater than100 ft)Clean times: Surface interval required for the diver to be considered clean for the next dive: 2 hours 20 minutes for repetitive group Alpha 15 hours 50 minutes for repetitive group Zulu

DCS PREVENTION3.DCS Prevention (During the Dive)Ascent Rate 30 feet per minute

4.DCS Prevention (Post-Dive)Exercise restrictions Both aerobic (e.g. running) and anaerobic (e.g. weight lifting) exercise performed within 4 hours after a compressed gas dive with significant decompression stress may be associated with an increased risk of DCSAscent to altitude restrictions (Up to 10,000 ft) Time/ascent Table - up to 29:15 for Repet Group Zulu 48 hours for Exceptional Exposure DivesManifestations of AGELoss of consciousnessConfusionFocal neurological deficitsCardiac arrhythmias or ischemiaCardiac arrest and death 4%

Causes of AGEPulmonary barotraumaIatrogenic events (radiologic procedures and cardiac bypass surgery)Right-to-left shunt

Small emboli in the vessels of the skeletal muscles or viscera are well tolerated, but embolization to the cerebral (CAGE) or coronary circulation may result in severe morbidity or deathTreatment of AGEThe primary goal of treatment is the protection and maintenance of vital functionsPre-hospital100% oxygen by rebreathing face maskSupine positionMaintain hydrationHBO is the treatment of choiceAdjunctive therapy: lidocaine, anticoagulant, corticosteroid39Benefits of HBOT1. Compression of existing gas bubbles2. Establishment of a high diffusion gradient to speed dissolution of existing bubbles3. Improved oxygenation of ischemic tissues and lowered intracranial pressure4. Reduction of ischemic-reperfusion injuryTreatment table selectionInitial treatment USNTT6 extend Table 6 or UNSTT6AFollow-up treatmentsDaily or twice dailyUntil complete relief of symptoms or until there is no further clinical improvement after 2 consecutive treatmentsUntil complete relief of symptoms or until there is no further clinical improvement after 2 consecutive treatmentsNo consensus: table 5, 6 and 9SummaryClinical diagnosisA sudden loss of consciousness or hemodynamic collapse during or immediately after any invasive procedure may indicate gas embolismHBOT is treatment of choice for AGE or VGE with paradoxical embolismGAS EMBOLISM (GE)Gas Embolism (GE) refers to all pathological events related to the entry or the occurrence of gas bubbles in the vascularTwo categoriesVenous gas embolism (VGE)Arterial gas embolism (AGE)Causes of VGESurgical ProceduresIatrogenic creation of a pressure gradient for air entryMechanical insufflation or infusionPositive pressure ventilationBlunt and penetrating trauma to the chest, abdomen, neck and faceCauses of AGEPulmonary barotraumaIatrogenic events (radiologic procedures and cardiac bypass surgery)Right-to-left shunt

Small emboli in the vessels of the skeletal muscles or viscera are well tolerated, but embolization to the cerebral (CAGE) or coronarycirculation may result in severe morbidity or death

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