Exercise testing for divers

1
Exercise testing for divers

• Stephen Glen

2
Exercise testing

• Is it safe?
• Does it help?
• What are we trying to measure?
• Who are we trying to exclude?

3
(No Transcript)
4
MA1 and exercise testing

• Step test recommended
• health promotion tool
• Looking for 13 METS
• HSE uses the legally defined so far as is
  reasonably practicable approach to safety
• However..

5
HSE and exercise testing

• Those undertaking step or exercise testing of
  divers may wish to be adequately trained in basic
  life support and resuscitation skills and may
  consider having access to resuscitation
  equipment..
• This may be
• woefully inadequate

6
13 METS

• 12 mins Bruce protocol (treadmill)
• For a 70kg subject this corresponds to a VO2 max
  of 3.2l/min
• Big people have a higher VO2 max than small
  people
• VO2 max per kg body weight 1 MET
• Multiples of 3.5ml/kg/min (metabolic equivalents
  /measurement in exercise training)

7
Step tests

• Designed to estimate VO2 max
• Heart rate measured in recovery
• If fit then small oxygen debt after exercise,
  repay more oxygen per heart beat, quicker
  recovery period
• Harvard Physical Fitness test (51cm platform) and
  Army Physical Fitness Test (43 cm) have only
  moderate correlation with VO2 max (r 0.4 to 0.7)

8
Who are we testing?
9
Who are we testing?
10
How often do problems arise?

• Anecdotal evidence 3 AMEDS have had serious
  complications during exercise testing
• There are usually warning signs (ECG monitoring)
• Risk of death / MI for exercise testing is approx
  1 in 2500

11
(No Transcript)
12
(No Transcript)
13
Is there evidence to help us?

• Similar population studies exist
• Fire fighters10 had positive testsNear maximal
  ECG stress testing and coronary artery disease
  risk factor analysis in Los Angeles City fire
  fighters. Barnard RJ et al. J Occ Med
  197517(11)693-5
• Norwegian sea pilots12 had positive
  testsCoronary heart disease in Norwegian sea
  pilots. Erikssen et al. Acta Med Scan Suppl
  198164579-83
• Sea captains10 had positive testsLatent
  ischaemia heart disease in sea captains. Mundal
  et al. ScanJ Work Environ Health 19828178-84
• Police officers9 had positive testsFrequency
  of physical activity, exercise capacity and
  atherosclerotic heart disease risk factors in
  male police officers. Williams et al. J Occ Med
  198729(7)596-600

14
What facilities are recommended?

• The ECG, heart rate and blood pressure should be
  monitored carefully and recorded during each
  stage of exercise The patients should be
  monitored continuously for transient rhythm
  disturbances, ST segment changes and other
  electrocardiographic manifestations of myocardial
  ischaemia
• ACC / AHA guideline update for exercise testing

15
HSE cardiac screening tool

• Is resting ECG normal?
• If abnormal has it been investigated?
• Is there a history or evidence of coronary artery
  disease, angina, MI, CABG, coronary angioplasty?
• Is there a history or evidence of cardiac
  arrhythmia, pacemaker, ICD?
• Peripheral vascular disease?
• Cardiomyopathy / heart failure?
• Uncontrolled hypertension or end organ damage?

16
Rose questionnaire

• In the past month have you had any pain or
  discomfort in your chest?
• Do you get this pain or discomfort when you walk
  uphill or hurry?
• Do you get this pain when you walk at an ordinary
  pace on the level?
• When you get any pain or discomfort in your
  chest, what do you do? (stop / slow down/
  continue)
• Does it go away when you stand still?
• How soon?
• Where do you get this pain or discomfort
  (diagram)?

17
Oxygen consumption when finning at the surface
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
Can we test fitness for diving work?
23
Is it safe or worthwhile to test divers as part
of MA1?
24
When is it worth exercise testing for coronary
disease?

• If asymptomatic then
• Male
• gt45 years
• One or more risk factor- hypercholesterolaemia-
  hypertension- diabetes- family history of
  premature disease
• ACC / AHA 2002 Guideline update for exercise
  testing

25
Are the results predictive?

• Metanalysis of 9 studies of asymptomatic patients
• 22,585 subjects
• Relative risk of cardiovascular events 4x normal
• False positives are common
• Commonest outcome is angina rather than MI or
  sudden death
• Exercise stress testing to screen for coronary
  artery disease in asymptomatic persons. Hlatky M.
  J Occ Med 1986281020-25

26
If exercise testing is required..

• Then it should be performed safely
• Continuous ECG monitoring
• Regular BP checks throughout
• Full resuscitation equipment available
• Staff trained to ALS standard

27
Conclusions from the HSE workshop

• No single ideal exercise test exists which can
  measure aerobic and physical demands of diving..
• .. withdrawing it was not considered an option
  since the test was regarded as a valuable health
  promotion tool encouraging appropriate standards
  of physical fitness amongst divers

28
We have been here before

• GP medicals for recreational divers
• Diabetics
• Asthmatics
• We are performing a test of dubious relevance
  with significant risk and little professional
  support

29
BSAC incidents
30
BSAC fatalities
31
DCI in the UK
32
What is the alternative?

• Remove the AMED exercise test completely
• Cardiovascular risk calculation
• Appropriately supervised cardiac exercise testing
  for those with a 5 year risk above an agreed
  threshold

33
(No Transcript)