The PFO in Diving and Space Exposure

Alfred A. Bove, MD, PhD Temple University Medical School Philadelphia, Pa

DISCLOSURE Relevant Financial Relationship(s) Consultant – Insight Telehealth Systems LLC Grant/Research Support – Astellas Pharma

Off Label Usage None

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Learning Objectives Familiarize the attendees on problems of inert gas kinetics in varying pressure exposures  Understand the role of Patent Foramen Ovale in various decompression environments  Improve knowledge of clinical decompression sickness syndromes 

      

The defect allows an intermittent R to L shunt Paradoxical embolism is possible Thrombus can migrate from RA to LA Risk for CVA may be increased Migraine headache may be related Risk for DCS may be increased Arterial desaturation is possible

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Pressure feet 16000 12000 8000 4000 -Sea level - 0 33 Depth 66 in 99 seawater 132 165

ATM 0.54 0.64 0.74 0.86 1 2 3 4 5 6

Altitude above sea level

mm Hg 412 483 564 656 760 1520 2280 3040 3800 4560

psi 8.0 9.3 10.9 12.7 14.7 29.4 44.1 58.8 73.5 88.2

Boyles Law 100

2.0% 2.4%

80

2.8% 3.4%

60

5.2%

5000 LUNG VOLUME - ml

4.1%

4000

40

3000

6.7% 9.0%

2000

20

1000

12.7% 19.2%

0 0

50

100 DEPTH -fsw

150

200

SURFACE

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32.7%

Henry’s Law 66 feet

Pressure - atm

3

N2 content proportional to Partial Pressure

2

PPN2 = 0.79•Pamb 1

Surface 0

3

6

9

12

DIVE TIME - hr

JBS Haldane

Boycott AE, Damant GCC, Haldane J: The prevention of compressed air illness. J Hyg (Cambridge) 8:342–443, 1908.

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Bubble Presence BUBBLE DETECTION STUDIES DIVE STUDY

DSAT 6x6 DSAT 4x6

DAN*

TOTAL DIVES

51

475

508

DIVES WITH BUBBLES

17

45

94

% WITH BUBBLES

33

10

19 * live aboard dive boat

Bubble presence 

Multiday Repetitive Diving

Transcutaneous Doppler 73% of 260 dives caused bubbles 93% of divers bubbled in one or more dives

Dunford et al, 1992

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Diving Disorders Direct Pressure Effects Barotrauma Ascent

Indirect Pressure Effects Decompression Sickness

Narcosis/HPNS

Other Marine Injury/toxins

Descent

Henry Pulmonary Barotrauma

Ear Barotrauma Perilymph Fistula

Arterial gas Embolism Sinus Barotrauma Pneumothorax

Boyle

Tooth Barotrauma Pneumomediastinum mask/suit barotrauma GI Barotrauma Alternobaric Vertigo

A variable intracardiac shunt at the atrial level

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Pulmonary Edema

ď Žâ€Ż

A PFO is needed in fetal life

Kizer, J. R. et al. N Engl J Med 2005;353:2361-2372

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Thrombus in a PFO

Doufekias, E. et al. J Am Coll Cardiol 2008;51:1049-1059

Copyright Š2008 American College of Cardiology Foundation.

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Incidence from 9 studies (1897-1984)    

8762 patients 2262 with PFO 26% incidence Range 17%-35%

40 PFO Incidence %



30 20 10 0 15

40

Age - yrs

Hagen et al. Mayo Clin. Proc. 59: 17, 1984

PFO Detection 

TEE, TTE, TCD   

Transesophageal Transthoracic Transcranial

46/111 (41%) patients with PFO 31/111 (28%) patients with PFO 42/111 (38%) patients with PFO

Klotsch et al Neurology 44:1603, 1994

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75



Echo contrast study of PFO



Bubble Studies

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PFO Bubble Study

What percent of patients with: …Cryptogenic stroke …Migraine …DCS

Have a PFO? What percent of patients with a PFO have …Cryptogenic stroke ? …Migraine ? …DCS ?

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PFO prevalence



PFO +

Stroke and PFO

PFO -

Total

Cryptogeni c

31/(77) 9(23)

40

Large Vessel

8/(26) 22(74)

30

Small Vessel

6/(30) 14(70)

20

Emboli c

5(26)

14(74)

19

0

2

2

Misc

Klotsch et al Neurology 44:1603, 1994

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ď Žâ€Ż

PFO and Stroke

The risk of recurrent stroke was: 2.3 % with PFO alone 15.2 % with both PFO and ASA 4.2 % with neither.

0 % with ASA alone.

Mas, et. al. NEJM 345:1740-1746, 2001

Recent Percutaneous Closure Registries Stroke Recurrence Hung Windecker Sievert Wahl Martin Braun Sommer

n=63 n=80 n= 281 n = 152 n=110 n=276 n=259

3.2 % 3.4% 3.1 % 4.9% 0.9 % 1.7 % 1.2%

Total: n = 1,221 pts (mean age 48 yrs ) Average recurrence

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2.4%



Migraine Headaches

MIDAS = migraine disability assessment score

Experimental Divers NEDU  88 divers, 444 dives  Extending air no decompression limits  DCS II in 6/88 

Latson GW et. al. UHM, 2008

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Navy PFO study

Experimental Divers 100%

Percent of Divers

PFO+ PFO80%

60%

40%

20%

0%

control

DCS

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Experimental Divers 100%

100%

control

DCS

Percent of PFOs

Percent of Divers

control

80%

60% 40%

20%

0%

GR 0

GR I

GR II

GR III

 Decompression

# Divers # PFO % PFO

None 109 26 24

60% 40% 20% 0% GR I

GR II

Sickness and PFO

early 50 33 66*

DCS

80%

late 35 9 26

limb skin 20 14 3 12 15 86*

109 sport divers with no DCS, 50 sport divers with DCS < 30 mins 35 sport divers with DCS > 30 mins Wilmshurst et al, 1990

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GR III

 Decompression

Sickness and PFO

26/78 DIVERS WITH PFO and NO DCS Professional

sport

Number

10

16

Age

35.9

32.7

Diving yrs.

12.8

7.5

No. Dives

650

236 Cross et al. BMJ 304:481, 1992

Cutis Marmorata

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

DCS and PFO DCS Type

1+ Shunt

2+ Shunt

Cerebral (20)

2(10)

14(70)

Control ( 2 0 )

2(10)

3(15)

Spinal ( 1 7 )

1(6)

5(29)

Control ( 1 6 )

2(13)

6(37)

1+

2+ Germonpre et al JAP 84: 1622, 1998

European Sport Divers

Torti, et al. European Heart Journal 2004 25, 1014

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European Sport Divers

Prevalence

30% 25% 20% 15% 10% 5% 0% pfo1

pfo2

pfo3

pfotot

PFO grade Torti, et al. European Heart Journal 2004 25, 1014

European Sport Divers PFO

No PFO

Total Divers

63

167

Total Major DCI

18

10

DCI Sx > 24 hrs

11

6

Recompression Rx

12

3

Torti, et al. European Heart Journal 2004 25, 1014

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European Sport Divers Self Reported Symptoms Minor DCI

Major DCI

bends

limb weakness

cutaneous erythema

cutaneous sensory level

extreme fatigue

bowel/bladder dysfunction

headache

paresis or paraplegia

dizziness

blurred vision

paresthesias

dysarthria

tinnitus

amnesia for the event hemiplegia loss of consciousness Torti, et al. European Heart Journal 2004 25, 1014

European Sport Divers

Torti, et al. European Heart Journal 2004 25, 1014

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 DCS

Risk MILITARY

SPORT

COMM

ALL

2,578K

43K

3,269K

Total Dives

648K

Total DCS

172

878

152

1202

86

649

9

744

2.65

3.41

35.3

3.68

DCS II 1.33

2.52

2.09

2.28

Type II DCS †

Incidence DCS

†

t

incidence per 10,000 dives Bove AA. Undersea and Hyperbaric Med. 25:175, 1998



Type II DCS Risk Risk

R/1,000 dives

P(DCS+/PFO+)

0.00047

0.47

P(DCS+/PFO-)

0.00019

0.19

RATIO = 2.52 P < 0.001 Bove AA. Undersea and Hyperbaric Med. 25:175, 1998

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PFO Closure Device

Percutaneous Closure of a Patent Foramen Ovale

Kizer, J. R. et al. N Engl J Med 2005;353:2361-2372

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

Percutaneous Closure

 PFO

Conclusions  Overall DCS risk is increased about 2 fold with moderate size PFO, 4 fold with large PFO  Absolute risk is small (0.047%)  Screening for PFO is not indicated  PFO is not a contraindication for diving  Echo should be done if DCS or AGE is unexplained

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The PFO in Space Common Problems with Decompression



Nitrogen Supersaturation Occurs on Ascent  Critical Supersaturation Produces bubbles  DCS Occurs in Aviation and Diving 

The PFO in Space 16 14

PRESSURE -psi

12 10 8 6 4 2 0 0

5

10 15 20 25 30 ALTITUDE - Thousands of feet

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35

40

The PFO in Space 1.0

atm.

0.9 0.8

8

0.7

Pressure

0.6

18

0.5 0.4 0.3

29

0.2 0.1 0.0 0

20

40

60

80

100

Altitude - 1000 ft

The PFO in Space 0.25

PO2

0.20

FiO2 = 0.21

0.15 0.10 0.05 0.00 0

20

40

60

Altitude - 1000 ft

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80

100

The PFO in Space

The PFO in Space

4.3 PSI, 0.3 ATA 100% Oxygen PO2 = 228 mmhg

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The PFO in Space 4.3 PSI 4 hrs, light exercise 100%

% DCS

80% 60% 40% 20% 0% 0

5

10

15

20

Prebreath hours

The PFO in Space ratio for 320 min tissue 2.50 10.2 PSI base 14.7 PSI base

TR

2.00 1.50 1.00 0.50 0.00 0

5

10

HRS

Suit Pressure = 4.3 PSI

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15

25

Space Station DCS Mitigation PHASE II

15

P

amb

-

psi

20

10 5 0 0

50

100

150

200

250

300

350

time - min

Tissue

N2

PP N2 - ATA

1 0.8 0.6 0.4 0.2 0 0

50

100

150

200

250

300

350

time - min

• Pilmanis et al., 1996; 8 cases of LVGE ❏ ❏ ❏ ❏

8/2470 subject-exposures with LVGE; all males All 8 Had Grade 4 VGE 7 of 8 had DCS (no serious symptoms) 7 of 8 evaluated for PFO 5 TEE: 1 Sinus venosus; 1 PFO; 3 negative PFO 2 TTE: 2 PFO 1 not evaluated

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Complications of Closure Type Fail placement Peric effusion Late complic Early Compl Late CVA Residual shunt Early compl Fail Placement Major compl Lte complications Late shunt Displacement/surg Tamponade Vascular Late compl AF early Visual early TIA Proced compl Failed close Early compl TIA early Recurrent events

% 6.25 3.125 12.5 12 6 6.4 5.1 6 3 3 33 1 1 4 4 8 6 1 6.6 26 7 3 16

No Pts 32

ASD 26

PFO 6

33

33

78

78

100

100

50

Purcell

140

140

Anzola 1 year

272

272

Alameddine

81

Khositseth

103

50

Comment Source Urgent surg Ridder 5 yr centesis surgery Surg study Gasiavelis 8.5 yr Ortho deox Guerin AF, clot,fist Herrmann 6 mo

22

29 months

The PFO in Space  PFO

Conclusions  Overall DCS risk is increased about 2 fold  Absolute risk is small  PFO is not a contraindication to space flight  Prospective Studies are needed to assess risk for DCS with a PFO in space flight

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