|
(CARDIOVASCULAR
RISK EVALUATION)
The British Medical Journal has printed this week an interesting review
entitled 'Evaluating cardiovascular
risk assessment for asymptomatic
people'. This is a daily problem in aeromedical practice so that the
conclusion
that ancillary testing adds little to the accuracy of prognosis
is relevant. The review comes from the Department of Internal
Medicine and
Clinical Epidemiology, Princess Alexandra Hospital, Brisbane, Australia.
The reference is I.
A. Scott, Evaluating cardiovascular risk assessment for
asymptomatic people, BMJ2009;338;164-168.
In a early thread, me jot here that the Cardiovascular Risk Assessment obtainable in a (computer) program form (or calculators) is derived
from the Framingham (cohort) sturdy (research). This study (first) identified (independent) risk factors (mathematically)
from a few score variables. Ah, then the risk of a IHD (cardiovascular event) is derived (calculated for every identified
risk factor over 5-years, or 10-years as desired, since the study is prospective over that number
of years, and more. Also, the relative
risk is calculated in a similar manner.)
Faults (errors) in the Framingham study not being cited, one
cannot find faults with the (mathematically sound) program (calculator).
I cannot get copy of this
(BMJ) paper. Me shall be grateful to receive this.
My summary (and my comments) on this paper:
A. The Framingham study (start 1948 – decades)-
(age, sex, hypercholesterolemia,
reduced HDL cholesterol, hypertension, LVH, DM, cigarette smoking identified
as risk factor).
Western
Collaborative Study (1976) – obesity, physical inactivity, family history of premature CAD (identified).
Both
above, comprise (the) First (computerised) program (calculator).
QRISK (1995 –2007) : – QRISK1 –
above (without LVH ) + Townsend measure of deprivation
QRISK2 : – QRISK1 + DM type 2 (instead of DM alone), rheumatoid
arthritis, renal disease, atrial fibrillation
ASSIGN (1984 –
1987) :– Framinghim study + family history + (Scottish index of) multiple deprivation (dosage of cigarette replacing
smoking status)
B.
The following (found in the payper) not appear accurate: "Among 25927 asymptomatic men (mean
age 43 years; 8 years coronary artery rate 0.6%), an abnormal stress electrocardiogram, which occurred
in only 4.3% of cases, incorrectly predicted death in 40% of cases, although accuracy improved with increasing number of risk factors (relative risk 21
for no risk factors; 80 for 3 or more factors).".
Not less accurate would be: The sensitivity of stress (exercise)
ECG is 85 (85%) cf. specificity 77%. (Roxy Senior, 2005)
C. (Concerning) coronary
artery imaging: Agatstone score (at pioneering stage some twenty years ago) employed (used) two different (radiological
techniques) in arriving at a score: a) Volumetric method, b) Density method. The density method is found not accurate
in doing follow up studies (especially follow up scans on patients on statin treatment), for reason here the treatment caused
shrinkage of (atheromatous) coronary plaques - the shrinkage of the calcification not being parallel, caused denser calcifications
found in the scannings). Not certain (whether, at present) only the Volumetric method followed (used).
Dr. Mydin
Ahmad Meer (Meer Ahmad), Lt. Col (Rtd),
MBBS (Mal), MPH (Mal), Dip Avi Med (USAFSAM), Dip Avi Med (UK), AM (Mal),
>>>Not less accurate would be: The sensitivity of stress (exercise) ECG is 85 (85%) cf. specificity 77%. (Roxy
Senior, 2005)
Error: Er.....This above is meant for Stress Echo.
(Chouhan (et al, 2003) replaced
lead V2 with V4R for a nonstandard 12 lead ECG during exercise testing. They show a 56% sensitivity for predicting coronary
artery disease with the standard 11 lead ECG and a 65% sensitivity when using their modified 12 lead system, with no change
in specificity (88%).)
Dr. Mydin
There is. Not forget (cardiovascular) risk factors ever; have a physical check up here done (regularly. Certainly,
when you're 49).
Tremendous fate, the dead diver not in the way; the new diver is skillfull enough to reach ground
without mishap.
Not forgetting in a recent past, a professional (African) soccer player died of a heart
attack during game. Would expect professional soccer player is fitter (compared) to skydiver. Ah then,
physical fitness is not a major risk factor in causing heart attack (some studies: not risk factor at all). Professional players
wrongly claim they should be far from succumbing to heart attack. Not crazy, not insist.
Get the medical records
(in order). This way, definitely, not anything is blur anymore.
Dr. Mydin Ahmad Meer (Meer Ahmad), Lt. Col (Rtd),
MBBS
(Mal), MPH (Mal), Dip Avi Med (USAFSAM), Dip Avi Med (UK), AM (Mal),
This discussion is thought provoking, since predictability has been bandied
about. Is it not known that sudden
death may be the first sign of heart
disease? My personal experience is that of a good colleague, and oral
surgeon
who was a marthon runner, non-drinker, non-smoker (vigorous
anti-smoking campaigner) who suffered cardiac death on a morning
run. He
was 44. On the AME circuit I have been told that about one U.S. airline
pilot per year suffers cardiac
death while at the yoke (despite the six
month exams and annual ecg). As a neurologist I have assumed that there
is
a small proportion of individuals who can suffer sudden cardiac death absent
any prior predictors. I would
like to understand this bettter.
Jack Hastings
You do not state if the friend (colleague) gets regular medical check--up (and whether any coronary calcification study
done, any risk-factors found, whether any treatment started, whether regular follow-up attended, whether religiously
following treatment advice.)
These (below) comprise risk-factors identified (to date, based on a 5000 cohort
in the Framingham study, 2 million primary health care patients in the QRISK study, 13,000 in the ASSIGN study. (One could
have a hunch anabolic steroids is a risk factor; that cocaine is a risk-factor, but they not. Based
on programs (calculators) prepared (developed), patient could have the patient's risk of a heart attack (a coronary
event actually, calculated) over a time of 5-years or 10-years (as required, and the relative risk).
(Ancillary
tests, that number close to twenty, such as for homocysteine, folic acid, 'highly sensitive C-reactive proteins', troponin, aldosterone,
fibrinogen, lipoprotein (a), are implicated as Risk Factors, but the above studies remark that results from these tests do
not change the patient's total risk in any significant manner).
Why is this possible that a heart artack is the
first cardiac event in a patient? Answer: a. The patient may not have had medical-check up recently viz-a-viz coronary risk factors. b. Risk ascertained, treatment starting, patient may not follow (be compliant
in a desired manner, particularly so because patient is asymptomatic.) Insufficient treatment (e.g. dosage of statins) happen; may
be a fault of patient, of doctor, or both. (In general, treatment in CV risk factors, are aimed at dyslipidemia, hypertension, DM, obesity, cigarette smoking. Where patient is not compliant, or where the treatment is not sufficient in this
person, the patient is at risk for a coronary event, although risk factors ascertained. c. A second most important factor
in a heart attack being the first cardiac event is the phenomena called plaque-rupture. The natural history of coronary
atherosclerosis is that the atheromatous plaques begin as small plaques, which at certain
points in the coronary
vasculature progress to 25%, 50%, 75%, 90%, or complete stenosis. Later, stages of stenosis cause angina pectoris; 90% - complete stenosis can
cause MI. Frequently enough though, and at a younger age, atheromatous plaques rupture at early, small stage, prior to
patient having any symptoms. Cause of such rupture not ascertained. A rupturing plaque triggers the blood clotting mechanism
at location, to cause a blood clot, thrombus,
to form at the site, causing acute stenosis - MI. CT-Scan Coronary Artery Calcification
Score ascertainment, provide early advantage there..)
A. The Framingham study (start 1948 – decades)-
(age, sex, hypercholesterolemia,
reduced HDL cholesterol, hypertension, LVH, DM, cigarette smoking identified as risk factor).
Western Collaborative
Study (1976) – obesity, physical inactivity, family history of premature CAD (identified).
Both above,
comprise (the) First (computerised) program (calculator).
QRISK (1995 –2007) : – QRISK1 – above
(without LVH ) + Townsend measure of deprivation
QRISK2 : – QRISK1 + DM type 2 (instead of DM alone), rheumatoid
arthritis, renal disease, atrial
fibrillation
ASSIGN (1984 – 1987) :– Framinghim study + family history + (Scottish index
of) multiple deprivation (dosage of cigarette replacing smoking status)
Dr. Mydin Ahmad Meer (Meer Ahmad), Lt.
Col (Rtd),
MBBS (Mal), MPH (Mal), Dip Avi Med (USAFSAM), Dip Avi Med (UK), AM (Mal),eq
It is possible to predict human errors from brain activity
ANYONE undertaking a repetitive or routine task knows the problem: suddenly something they have done dozens or hundreds
of times before goes wrong. In a factory it might mean that a component has to be thrown into the scrap bin. But in some occupations,
like operating a giant crane or piloting an aircraft, the consequences can be devastating.
Human errors are often put down to a momentary loss of concentration. But it now appears that sometimes a localised change
in brain activity can be involved. Not only does that change contribute towards making a mistake, but also the type of brain
activity is detectable before the mistake is made. That means it could be used to help predict, and so possibly prevent, some
human errors.
The human brain is a complex organ, but it is becoming better understood with the use of functional magnetic-resonance
imaging. This uses a large scanner to detect changes in the blood flow in parts of the brain that correspond to increases
or decreases in mental activity.
A team of researchers from laboratories in America, Britain, Germany and Norway used an imaging machine to scan the brains
of a group of volunteers who were set a “flanker” test. This measures performance in the presence of distracting
information: they were asked to respond as quickly as possible to the direction of an arrow flanked by other arrows that point
in the same or opposite direction. Although the task is simple and repetitive, to keep providing the right answer demands
a fair bit of brain power: people make a mistake about 10% of the time.
When performing correctly the volunteers' brains showed increased levels of activity in those parts associated with cognitive
effort, as would be expected. However, these areas gradually became less active before errors were made. At the same time
another set of regions in the brain became more active. These regions are part of a so-called “default mode network”
and show increased used when people are resting or asleep.
This is not to say that people are falling asleep on the job. Exactly what this network does is not fully understood, but
it seems to be related to how much effort or resources the brain is prepared to put into performing a task. In one sense,
the brain could be trying to economise during a repetitive task by shifting resources to the default mode. Once a mistake
has been made and detected, people quickly snap out of the default mode.
What this means is that brain activity can be used to predict the likelihood of someone making an error about six seconds
in advance, with gradual changes starting as much as 30 seconds ahead of time, the group reports this week in the Proceedings
of the National Academy of Sciences. This, the authors add, implies it is unlikely that errors made during repetitive
or monotonous tasks arise solely from a sudden moment of lost concentration.
Imaging machines are far too big and complex to be used in workplaces to monitor the brain activity of people engaged in
important tasks. But Tom Eichele, of the University of Bergen, Norway, the lead author, says the team hopes to study another
way of detecting the observed activity pattern, by correlating it to changes in electrical activity in the brain. These can
be measured by electroencephalography (EEG), using electrodes placed on the scalp.
Small, portable EEG monitors are already available. Indeed, they have even been incorporated into
baseball caps. A lightweight head device is also being developed for people to interact mentally with computer games. So,
if EEG features can be found that correspond to the change in brain activity which the researchers
have observed, then a hat that gives warning of an imminent mistake might one day become reality.
Readers' (comment) page
: Aviat Space Environ Med. 1984 Jun;55(6):497-500.
The consequences of in-flight
incapacitation in civil aviation.
Chapman PJ.
Aviation medical
standards world-wide place much emphasis upon the cardiovascular (CV) status of the individual. This is justified, especially
in the Western world, because of the high incidence of CV disorders in the population and their likely similar occurrence
in the aircrew peer group. These standards do not in general require the demonstration of any objective short fall in performance,
but rather guard against a potential threat, that of sudden incapacitation. However, some observers have sought to question
whether or not this threat and its potential consequences is as great as it might appear and to quantify the risks. We have
now carried out and analysed over 1,300 closely observed simulator exercises, using two protocols, in which sudden and subtle
incapacitation has been programmed to occur to the handling pilot at a critical phase of flight. The results have been assembled
and extrapolated with the recorded incidence of sudden incapacitation in flight in civil airline operations so the actual
degree of risk can be identified. Conclusions can be drawn from this on the relevance of present cardiovascular standards
and suggestions for improvement are made.
PMID: 6466244 [PubMed
- indexed for MEDLINE]
Excerpt JAA Manual of Civil Aviation
Medicine
(No human activity is totally free from risk. Transportation
is such an activity and the risk attached varies
widely according to mode. Aviation was initially a high risk, but with
the introduction of modern jet
passenger aircraft and improved instrument approach and landing systems the fatal accident
rate has
continuously fallen. The present rate world wide is better than 0·5 per 106 flying hours with some countries
achieving
0·2 per 106 flying hours. The average flight time is approximately one hour and so it would seem
reasonable to aim for
an accident rate of 0·1 per 106 flying hours or 1 per 107 hours or 1 per 107 flights.)
(In this overall
risk it is considered that no system (airworthiness, air traffic, operations) should contribute
more than 1/10 of the total
(1 per 108) and since the health of the pilot is only a small part of the
operational risk, (e.g. 10%), medical cause for
fatal accidents should occur no more often than 1 in
109 hours (10-9)).
>>> Regulatory
bodies, airlines, etc wish to see (Commercial) Air Transport Provider Systems in terms of airworthiness, air traffic, operations,
etc., (lumping medical/health onto operations). Expect not more than percent 10 (10%) in airworthiness, air traffic, operations,
etc. Expect health (medical) here cause no more than 10% those did happen (in operations.)
(If we consider the pilots
of a large jet passenger aircraft, it has been proposed that a 1% per annum risk of
their incapacitation would meet the
target rate above.)
(This proposed rate is roughly equivalent to the best
experience
following myocardial infarction or coronary artery by-pass surgery. Since cardiovascular
disease accounts for about 50%
of permanent loss of licence in Western European and North American
aircrew, it is one of the most likely causes for sudden,
complete incapacitation and therefore a good
example of risk assessment. One per cent per annum is one incapacitating event
per 100 pilot years or
100 x 8 760 hrs. If 8 760 is approximated to 10 000 then this is 1 event in 100 x 10 000 hours or
106 hours.)
(If a pilot with this risk of incapacitation is flying a large jet passenger aircraft with
a qualified co-pilot, the
theoretical risk to the flight is that of double incapacitation, less frequent than 1 in 1012
hours, or very long
odds. Such an assumption is based upon perfect handover. Simulator testing would indicate that handover
in
such cases is virtually always successful but the real incapacitation is not always recognised and a 99%
successful handover
is suggested as being more realistic. A further factor is that incapacitation becomes
critical only during landing or take-off,
approximately 10% of an average one hour flight.)
(At worst case, a pilot with 1% per annum incapacitation risk, (where
handover is not completed at the time
of his incapacitation) poses a threat to the aircraft of one in 106 flying hr/flts.
If only 10% of that flight is
critical the odds lengthen by a factor of 10 (one in 107) and if only one per cent of handovers
fail, the odds
lengthen again by a factor of approximately 100 (one in 109 flying hr/flts).)
>>>
Returns to the same (original) rate derived from present accident-rates (i.e. that which is expected. Convincing). The best
experience, this should be found to extend (to cover every medical sudden incapacitation cause) more than just the percent
50 (50%) that is heart attack (myocardial infarction), CABG. Want (responsibility) here is not ambiguous.
Dr.
Mydin
I did read throught the paper, 'Chapman P.J.C. (1984). The consequences of in flight
iincapacitation in civil
aviation
medicine', my mind open.
My sentiment (opinion):
a. The first part 'Series 1', (where simulated 'hazard
was present to the aircraft' at the time of sudden incapacitation simulation) is (really) not relevant. For reason, the results
are not discussed under 'Discussion', not under 'Summary'.
b. 'Series 1' state 'in this form, 500 consecutive incapacitation
exercises were recorded.'. 'Series 2' (which is really relevant to the discussion, conclusion, summary) not stated the manner
in which the 800 exercise subjects (in Series 2) are chosen. Assuming 'Consecutive' (like in Series 1), results would not
be accurate (compared to a sample of subjects selected from a pilot population in a random manner such that the degree of
hazard created, and the number of crashes discussed in 'Results' reflect random selection ). Description of subjects not given
(e.g age, total flying hours achieved by both aircraft type, simulator type, rank, number of times done incapacitation drill
prior. Were there repeat subjects?)
c. The paper lacks for reason here data was complete not.. (Only data from IATA
carriers are discussed). He have to find out, "would the results be different (were data from non IATA carriers were included)?
d.
There is some 204 total medical incapacitation in 'Series 2'. Of these 13, caused by 'heart attack' (myocardial infarction).
Yet, the 'probability of accident occurring' (arrived at under discussion) is based on 13, and not 204. Yet, the probability
arrived at, 10^-10, is then compared with the total recommended probability (risk) recommended for 'airworthiness' (by both
JAA and FAA). (I hope, the assumption made by the author 'a modest 600 flying hours per pilot per year is generally acceptable.
Presumably, such asumption is made because of inavailability of vital data)
e. The probability arrived i.e. 10^-10,
in case the total 208 (used instead of 13), probability is now 5 x 10^-7, and not 10^-10. The (JAA,FAA) recommended probability
(for airworthiness actually) is an'extremely improbable' 10^-9 (concommittant adverse operating conditions not present when
sudden incapacitation occurs), 'improbable' 10^-5 - 10^-8 (when present). It seem the ability of our Physical (Medical)
Check Up (both Pre-selection , Periodic) falls short of this requirement by both JAA, FAA.
f. (The paper discusses
results obtained for 'sudden incapacitation for myocardial infarction', then draws conclusion for sudden incapacitation due
to medical causes as a whole.)
(At best, this study is preliminary, but it underlines the necessity to keep data at
every vital station, for every disease that could cause sudden incapacitation, the periodic analysis of such data, in that
the Medical Checkups prescibed by the regulatory authorities achieve the standards of safety set by them. It also provides
a viable method, also the manner that analysis could be carried out).
A second study (adapting the methodology in this
study) would be of higher order (is ordered), timely.
Dr. Mydin
|
1: Aviat Space Environ Med. 2002 Mar;73(3):194-202.
The age 60 rule: age discrimination
in commercial aviation.
Wilkening R.
Department
of Occupational and Environmental Medicine, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. rmwilkening@earthlink.net
BACKGROUND:
The Federal Aviation Administration's Age 60 Rule, promulgated in 1959, prohibits airline pilots from working in Part 121
operations once they have reached the age of 60. The Age 60 Rule remains a most contentious and politically sensitive topic,
with challenges to the Rule currently mounted in both legislative and legal arenas. METHODS: An extensive review of the medical
literature was accomplished using MEDLINE. Pertinent Federal Regulations were examined. Legal proceedings and public domain
documents were noted. Letters and personal communication were solicited where necessary information could not be ascertained
by other means. RESULTS: The Age 60 Rule was not based on any scientific data showing that airline pilots aged 60 and older
were any less safe than younger pilots, and there is evidence to indicate that the choice of age 60 was actually based on
economic rather than safety considerations. Airline pilots consistently exceed general population norms for longevity, physical
health, and mental abilities. Fear of an adverse pilot health event causing a crash in standard multi-crew operations is not
justified. For decades, airline pilots under age 60 have been granted the means to demonstrate their fitness for flying by
taking medical, cognitive, and performance evaluations that are denied to airline pilots when they reach age 60. Actual flight
experience demonstrates that older pilots are as safe as younger pilots. International aviation experience indicates that
abolishing the Age 60 Rule will not compromise aviation safety. CONCLUSION: There appears to be no medical, scientific, or
safety justification for the Age 60 Rule. As such, perpetuation of the Age 60 Rule, where age alone is used as the single
criterion of older pilot fitness, represents age discrimination in commercial aviation.
PMID:
11908884 [PubMed - indexed for MEDLINE]
1: Aviat Space Environ Med. 1988 Mar;59(3):278-81.
Links
Air accidents, pilot experience,
and disease-related inflight sudden incapacitation.
Froom P, Benbassat J, Gross M, Ribak J, Lewis BS.
Israel Air
Force Aeromedical Center, Tel Hashomer.
The
epidemiology of sudden death, the etiology of inflight sudden incapacitation, and the influence of pilot age and experience
on air accident rates are reviewed in order to determine the aeromedical emphasis needed to minimize accidents. Sudden deaths
in men over age 35 are nearly all due to coronary artery disease, whereas in those under 35 years they are mostly due to hypertrophic
cardiomyopathy. The incidence of fatal accidents from human error is, however, far greater than that from physical illness.
Since inexperienced pilots have a 2-3 times increased incidence of mishaps due to pilot error, the estimated risk of disease
related in-flight sudden incapacitation should be balanced by consideration of pilot experience. Therefore, it may be preferable
to grant waivers to experienced pilots with an increased incidence of disease-related inflight sudden incapacitation than
to replace them with novices. We conclude that overly strict medical criteria may paradoxically increase accident rates.
PMID:
3355485 [PubMed - indexed for MEDLINE]
1: Aviat Space Environ Med. 1978 Oct;49(10):1225-8.
U.S. fatal general aviation accidents due to cardiovascular incapacitation: 1974-75.
Mohler SR, Booze CF.
A
study was undertaken to determine the relative impact of inflight cardiovascular incapacitation among general aviation pilots
with respect to general aviation flight safety. During calendar years 1974-75, the National Transportation Safety Board reports
reveal that 13 U.S. general aviation pilots died of cardiovascular incapacitation during flight. The analysis of these accidents
will bear on any suggested changes in pilot medical screening procedures for cardiovascular disease, as well as on pilot safety
education programs. Of the 13 cases noted above, nine pilots were flying alone. Of the remaining multiple occupant cases,
the nonpilot wife of one deceased victim managed to land the aircraft. Eighteen deaths resulted from the inflight incapacitations.
The ages of the pilots ranged from 33-68 years, with both a mean and a median of 52. Postmortem examinations revealed extensive
coronary disease (atherosclerosis) in 12 cases (no pilot autopsy data is available in the case where the passenger landed
the aircraft). Of these 12 cases, five demonstrated recent occlusions. In four more, evidence of old infarcts was revealed
by the postmortem examination. It is concluded that these 13 inflight cardiovascular incapacitations, occurring among a total
of 1,404 fatal general aviation accidents in the 1974-75 period, constitute such a small proportion (0.93%) of the documented
fatal general aviation accidents that extensive additional cardiovascular screening procedures are not justified at present
on cost/yield basis.
PMID:
708352 [PubMed - indexed for MEDLINE]
1: Aviat Space Environ Med. 2001 Nov;72(11):1025-33. Links
Comment in:
Aviat Space Environ Med. 2001 Nov;72(11):1034-6.
The use of EEG in aircrew selection. Hendriksen IJ, Elderson A.
Netherlands Aeromedical Institute, Dept of Research and Development.
hendriksen@akb.azr.nl
The value of the electroencephalograph (EEG) as a screening device in
aviation medicine is questioned, because few subjects
are disqualified
on grounds of an EEG exam. At the Netherlands Aeromedical Institute,
pilot applicants
are rejected with a diagnosis of epilepsy or with
severe EEG abnormalities (including epileptiform patterns where epilepsy
is
highly suspected). Although several studies have shown a low incidence
of epileptiform EEG abnormalities in candidate
pilots, subjects with an
epileptiform EEG have a substantially increased risk of sudden
incapacitation during their
flying careers. In this review, we calculate the
probability that a candidate with epileptiform EEG, but no history of
epileptic
seizures, will develop seizures during his flying career. This
probability is about 25%, more than 12 times higher than
for subjects
with normal EEG and no history of epileptic seizures (2%). Subjects with
epileptiform EEGs not only have
increased risk of future
epileptic seizures, but additionally it is recognized that
epileptiform EEG discharges may
be associated with episodic functional impairment,
which can be a danger when a subject is flying. Taking this into
account,
one should consider rejecting all candidates with epileptiform EEGs
in the future. This is at the expense of a small group
of subjects
with false-positive EEGs, but we believe that concern for public safety
must override other considerations
in these rare cases. To improve the
understanding of the usefulness of the EEG in pilot screening procedures,
an international
classification and coding system should be developed,
so that data from different countries can be compared.
("When selecting candidates for training, it must be remembered that
epilepsy is one of the commonest
medical disorders associated with
accidents due to physical incapacity (Taylor, 1983: raffle 1983). In
addition, it
has been shown that trainee pilots with paroxysmal/abnormal EEG's
had a threefold increased crash rate compared with those
pilots with
normal EEGs (Lennox-Buchtal, Buchtal, Rosenfalk 1959). Epilepsy is a
common disease with a prevalence of
percent 0.5 - 0.8 in the population. A
predisposition to epilepsy is usually persistent, so the risk of a
seizure over
the professional lifespan of aircrew is cumulative. Any
incident in the patient's history that indicates an increased risk
of
epilepsy, for example seizures occurring after the age of 5, a severe head
injury, or other illness with a hvery
high risk of epilepsy , should
exclude that person from selection. In addition thec occurrence of
generalized or focal
spike-wave paroxysms on an EEG suggest a
predisposition to epilepsy, and it is recommended that an EEG should be
an
integral part of the initial medical examination, and that those
with the above abnornalities (usually 0.5 - 0.7 %) are
considered unfit
for training.
The overall risk of traumatic epilepsy after a closed head injury is 1
-5 %, and
this risk is increased if one or more of certain
complications occur
:
Penetrating brain injury 40% increase in risk
Depressed
fracture of skull vault 15%
Intracranial haemotoma 35%
Intracranial haemorhhage 35%
PTA 24 hours 4 %
Early seizure
25%
This risk being cumulative and rising to as high as &0%. If seizures do
occur, 27% do so within the first
3 months. 56% within the first year,
and 75% within 2 years (Jennet 1975) An early seizure is one occurring
within the
first week after head injury, and associated with 25% risk
of recurrence of seizures; risk of epilepsy developing ater
a late
seizure, the risk of recurrence is 80%)") (RTG Berry in Neurology in
Aviation Medicine Ernsting/King (1988)).
('These results raise the question of the usefulness of the EEG as a
screeing tool for aircrew selection.
Everett, Jenkins (1982) attempted
to determine the benefits and costs of EEG to the US Air Force and
concluded
that it was 'worthwhile' for fighter pilots. Epileptic seizures
are a common cause of sudden in-flight capacitation (Rayman
1973), and
one avoided incident would fund the screening programme for many years.
There is also concern of the possible
effect of transient subtle
cognitive deficits on flight safery caused by 'asymptomatic epileptiform'
discharges (Kasteleijn
Noist Trenite et al 1987).
The revelations that appeared in the Japanese press last week painted a chilling portrait of a pilot with
a troubled psyche. There were claims that Seiji Katagiri had been suffering from hallucinations and feelings of depression.
He once summoned police to his two-story house near Tokyo because he was convinced it was bugged, but a thorough search turned
up no eavesdropping devices. On three occasions, his employers had urged him to see a psychiatrist. Ever since he was granted
one month's leave in November 1980 for a "psychosomatic disorder," Katagiri's wife has worried about his neurotic behavior.
Her reported fears proved tragically prophetic. On Feb. 9, as Flight 350 approached Tokyo's Haneda Airport,
Katagiri apparently threw two of the four engines into reverse, causing the plane to plunge into Tokyo Bay some 300 yds. short
of the runway. Of 174 passengers and crew aboard the Japan Air Lines DC-8 bound from Fukuoka, 24 people died. Police claimed
last week that Katagiri told them he felt ill the morning of the flight. Said he: "After I switched from auto to manual operation
just before landing, I felt nausea, then an inexplicable feeling of terror, and completely lost consciousness."
The Japanese catastrophe raised new concerns about airline standards that determine a pilot's fitness to fly.
The Federal Aviation Administration requires that a U.S. commercial pilot pass a rigorous physical examination every six months,
as well as an assessment of his or her emotional stability. The failure rate is low; an FAA study showed that for every 1,000
pilots tested, only eight are denied certification for medical reasons, and only two of those for psychoneurotic disorders.
Those who flunk are automatically grounded until they can pass the examination. Most international airlines conform to the
FAA requirement that their pilots pass regular proficiency tests for the specific planes they operate. Japan Air Lines last
week apologized for allowing Katagiri to fly, admitting that he was reinstated as captain even though he had not fulfilled
the JAL rule that pilots log at least 25 hr. of flying time a month.
Apart from accusations that he cracked up at the controls, Katagiri may face criminal indictment for abandoning
his passengers and plane so quickly. "It's unbelievable that he was among the first to take the rescue boat," said JAL President
Yasumoto Takagi. Pictures later showed the captain, with a bland expression and wearing a cardigan, aboard a bus after he
had reportedly told officials he was an office worker. He could receive a five-year jail term if convicted under Article 75
of Japan's civil aviation law, which requires a pilot to do his best to minimize casualties and property damage in a plane
crash. -
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