Arterial Gas Embolism & pulmonary barotrauma

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Runtime: 45 min

Slides: 35

Mattijn Buwalda

Anesthetist-intensivist

& dive medical physician

• Jill 35 yrs, OWC 22 dives • Dives with the much more experienced Robert

(UW photographer) • Jill runs out of air at @ 35 msw, panics and shoots

for the surface • Robert is focused on taking pictures of a lionfish

15 meter away from Jill

Case

• Jill makes a ‘ballistic’ ascent.

• On surfacing she makes a high pitched noise and looses consciousness within 1 min.

• It took 10 minutes before she was finally on deck of the boat

• BLS by the divemaster

• SAR evcuation

• Declared dead after 90 min of CPR

Case

Most feared and

serious dive injury!

Arterial Gas Embolus (AGE)

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• pulmonary barotrauma

• arterial gas embolism (AGE)

• cerebral gas embolism (CAGE)

• venous vs arterial gas embolism (VAGE)

• pathophysiology

• signs & symptoms

• clinical VGE

• HBOT for AGE

• adjuncts

• take home

AGE content

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• immediately after surfacing rare

• 4% will die on the scene

– sudden loss of consciousness, PEA

– no effect of CPR

– die on surfacing

– complete filling of central veins and arteries

• 5% will die in hospital

Divers AGE: sudden death

Neuman, Tom S (2003). Arterial Gas Embolism and Pulmonary Barotrauma". In Brubakk, Alf O; Neuman, Tom S. Bennett and Elliott's physiology and medicine of diving (5th ed.). United States:

Saunders Ltd. pp. 557–78

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• usually: uncontrolled ascent (panic) without

exhalation

• ascent from 1 m depth with total lung volume!

• airway obstruction in asthma

• presence of blebs and bullae

Pulmonary barotrauma

Benton PJ, Woodfine JD, Westwook PR. Arterial gas embolism following a 1-meter ascent during helicopter escape training: a case report. Aviat Space Environ Med 1996;67:63-4

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Predisposing factors

• blebs/ bullea

• asthma

• sarcoidosis

• tumors

• pleural adhesions

• pulmonary fibrosis

• infection

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Pulmonary barotrauma

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• high pitched cry on surfacing

• dyspnoea

• cough

• haemoptysis

Pneumomediastinum

• no pain or substernal chest pain

• ascending air to the neck >

subcutaneous emphysema

• chest x-ray: look along the edge

of the heart, aorta

• pneumothorax is not necessary

• HBO is not needed (unless AGE)

• conservative treatment, 100% O2

• no flying for 1 week after

resolution.

• ruptured alveoli > perivascular sheaths > bronchi >

mediastinum

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Pneumomediastinum

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• rupture of alveoli adjacent to visceral pleura

• less common

• occurs in 5-10% of AGE

• very relevant for the chamber!

• symptoms:

– pleuritic chest pain

– SOB, dyspnea

• CT scan is more sensitive

• echo: absence of sliding sign

• usually small pneumothorax:

– 100% oxygen

– observation

Pneumothorax

Pearson RR,: Diagnosis and treatment of gas embolism. In: Shilling CW, Carlston CB, Mathia RA (eds): The physicians’s guide to diving medicine. New York, Plenum Press, 1984, pp 333-367

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Pleural tear

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Arterial gas embolus (AGE)

• organs at risk:

– flow: heart and brain

– not gravity!

• ischemia due to

arteriolar occlusion

• endothelial damage – platelet adhesion

– vasodilation

– loss of auto-regulation

– loss of blood-brain barrier >

edema

Butler BD, Laine GA, Leiman BC, et al. Effects of Trendelenburg position on the distribution of arterial air emboli in dogs. Ann Thorac Surg 1988;45:198-202

Melhorn U, Burke EJ, Butler BD, et al. Body position does not affect the hemodynamic response to venous air embolism in dogs. Anesthe Analg 1994;79:734-9

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• most bubbles pass through the cerebral

circulation

• occlusion at diameter 30-60 µm

• junction white/grey matter

Pathophysiology cerebral AGE

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Cerebral symptoms, not spinal!

• loss of consciousness

• stupor, confusion

• cortical blindness

• monoplegia

• asymmetric

multiplegia

• paresthesias

Cerebral AGE

• convulsions

• aphasia, visual field

defects

• vertigo, dizzyness

• less frequent:

– complete hemiplegia

– paraparesis

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CAGE

• spontaneous improvement due to

breaking up and redistributing

• deterioration due to microthrobus and

edema formation!

• combination with DCS!

• CK (mm) is correlated to severity and

neurological outcome

Smith RM, Neuman TS. Elevation of serum creatine kinase in divers with arterial gas embolism. NEJM 1994;33:19-24

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CAGE bubble

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AGE

• pulmonary barotrauma

– emergency ascent without exhaling!

– blebs and bullae

– arterial gas embolism

• Iatrogenic or DCS:

– direct intra arterial injection

– VGE + R > L shunt (PFO)

– VGE + pulmonary pass through (massive gas load)

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• high ambient pressure:

– modest bubble reduction!

– T6a (6 bar) vs T6 (2.8 bar)

• high O2 partial pressure

– to speed up N2 washout (N2 gradient)

– to increase plasma O2 content (oxygenation)

– to decrease cerebral edema (vasoconstriction)

– to antagonize β2 integrin mediated capillary

blockage

– to reduce I/R injury

HBO for AGE

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Mechanical effects of HBO

From 1 > 2.8 bar

volume reduction 73%

diameter reduction 35%

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Modest effect from

compressing to 6 bar

Table 6

UHMS Best Practice Guidelines Prevention and Treatment of Decompression Sickness and Arterial Gas Embolism 2011

Van hoesen K, neuman TS. Gas embolism in Physiology and medicine of hyperbaric oxygen therapy. Neuman TS, Thom SR (eds) 2008, saunders, elsevier, Philadelphia

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• Trytko & Bennet AGE review 1996-2006 • 18 diving related AGE

• 12 rapid ascent

• 4 PFO (TEE confirmed)

• 2 suspected PFO (not confirmed TEE)

• average treatments 3.6

• treatment delay 4 - 44H

• complete resolution 15/18 = 83%

• minor residual symptoms 3/18

Case series

Trytko BE, Bennet MH. Arterial gas embolism: a review of cases at prince of wales hospital, Sydney, 1996 t 2006. Anaesth Intensive care 2008;36:60-64

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• 100% O2 by mask (class I, level C)

• normal saline (class IIb, level C)

• lidocaine 1.0 mg/kg, 2-4 mg/min iv. (class

IIb, level C) = obsolete…..

• thrombosis prophylaxis (class I, level A)

Adjuncts to treatment

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Chest drain

• diver with pneumothorax

– before air evacuation

– before recompression

• inside chamber

– problems arise during ascent!

– stop ascent, descent 2 meter

– insert chest drain with Heimlich valve

– or emergency needle thorococentese

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TTE: absence of sliding sign

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• return to diving?

– if symptom free

– no pulmonary contraindication

– HRCT lung

– after 1 month

– If spontaneous pneumothorax or bronchial

rupture due to blebs and bullae > no more

diving!!

Return to diving

UHMS Best Practice Guidelines Prevention and Treatment of Decompression Sickness and Arterial Gas Embolism 2011

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• problems arise during ascent

• or shortly after surfacing (minutes)

– altered consciousness

– confusion

– focal cortical signs

– seizure

• treatment the same as DCS

• 100% O2

• supine flat or recovery position

• evac < 1000ft to HBOT

• deterioration after improvement is possible,

always evacuate for HBOT

Take home message

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• sudden unexplained neurological,

pulmonary or cardiac abnormality during

or shortly after an invasive procedure

• such as:

– central line insertion, removal or manipulation

– delivery

– neurosurgery

Clinical iatrogenic gas embolism

• doppler ultra sound of heart

• Echocardiography

• CT scanning

• Or straight to HBOT 29

lung filter! (bubble > 22 µm)

• pulmonary pass through:

– dose

– injection speed

– pressure gradient

Venous gas embolism

venous air entry:

• diving DCS

• clinical:

central venous catheter

neurosurgery (sitting)

CABG

prostatectomy

hip/spine surgery

Cesarean section

et al.

• large volume >

vapour lock/ chokes

Arterial Gas Embolus

(AGE)

Fukaya E, Hopf HW. HBO and gas embolism. Neurol Res 2007;29:142-145

• low volume >

no symptoms

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• pulmonary filter overwhelmed above:

– 0.4 ml/kg/min (dog)

– 0.17 ml/kg/min (sheep)

• lethal bolus of intravenous air (air lock)

– rabbits 0.55 ml/kg

– dogs 7.5 ml/kg

– human (case reports) 3-5 ml/kg= 200-300 ml

How much air?

Toung TJ, Rossberg MI, Hutchings GM. Volume of air in a lethal venous air embolism. Anesthesiology 2001:94:360-361

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Hemiplegia after CVC insertion

only air in

• ophthalmic vein

• central venous sinus

• brachiocephalic vein

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• VGE massive:

– cardiac massage dislodges the vapour lock!

– HBO (no data, risk/ benefit of transport)

• VGE mild:

– supportive, 100% O2

– pulmonary edema > HBOT

• + neurological or cardiovascular signs: HBOT

– up to 24 hours after incident (3-48 h)

– table 6 = 2.8 ATA

Therapy AGE & VGE

Yeh PA, Chen HP, Tsai YC, et al. Succesful management of air embolism-induced ventricular fibrillation in orthotopic liver transplantation. Acta anaesthesiol. Taiwan 2005;43:243-246

Wherret CG, Mehran RJ, Beaulieu MA. Cerebral arterial gas embolism following diagnostic bronchoscopy: delayed treatment with hyperbaric oxygen. Can J abaesth 2002;49:96-99

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• Wondwossen G, case series 1990-2012

– 36 patients iatrogenic CAGE

– neurologic signs: global > focal

– 26/36 = 72% favourable outcome

– + younger patients (< 44 yr)

– + time to HBO < 6 h

– - presence of infarct or edema before HBOT

Case series

Wondwossen, et all. Factors associated with favorable response to hyperbaric oxygen therapy among patients presenting with iatrogenic CAGE. Neurocrit care 2013;18:228-33

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Thank you for listening.

Contact: mattijnb@gmail.com

Slides available @

www.mattijnb.nl