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GastroIntestinal Disease
INTRODUCTION
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GI disease is common in the aviation environment and may cause incapacitation in crew or illness
in passengers.
Acute GI illness, which frequently is self-limiting or relatively easily treated, is commonplace.
A poorly predictable relapsing and remitting course characterizes some of the chronic GI
conditions.
GASTRO-OESOPHAGEAL REFLUX DISEASE (GORD)
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Common disorder in developed countries:
o Up to 60% of population experience symptoms at some time
o Heartburn and regurgitations
o Aggravated by postural change and relieved by antacids.
Frequently other symptoms ➪possibility of alternative diagnoses.
o Dysphagia
o Weight loss
o Vomiting
o GI bleeding
Exclusion of other diagnoses (++peptic ulcer disease) = priority in aviation environment.
o Most patients will be referred for endoscopy.
o Many patients with GORD will be investigated for Helicobacter pylori.
Management of GORD involves:
o Lifestyle measures
 Weight reduction
 Smaller and more frequent meals
 Sleeping with head-of-the-bed raised.
o Acid neutralization or suppression
 Antacid/alginate drugs
 Proton-pump inhibitors
o Surgical treatment may be indicated for young patients with severe reflux.
Restriction of aircrew status is rarely required.
PEPTIC ULCER DISEASE
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Has much less effect on aeromedical fitness than in the pass.
Prevalence has decreased in developed countries over recent decades, in parallel with the
decreased prevalence of Helicobacter pylori.
Eradication of H. pylori heals ulcers and dramatically reduces relapse rate.
o ➪Reduced prevalence and complication rate in the aviator group.
Symptoms:
o Pain related to eating
o Nausea
o Vomiting
o Weight loss
The major aeromedical concerns are the complications:
o Bleeding
o Perforation
o (Anaemia and gastric outflow obstruction).
Cure is to be expected and can be confirmed ➪most aviators can expect to return to unrestricted
flying activity after treatment.
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INFLAMMATORY BOWEL DISEASE
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Inflammatory bowel diseases comprise:
o Microscopic colitis:
 Collagenous colitis
 Lymphocytic colitis
o Ulcerative colitis (UC)
o Crohn's disease (CrD)
o UC and CrD have a relapsing and remitting course, variable response to treatment, cause
difficulties for patients, licensing authorities and employers: ➪ often disqualifying for
recruits.
Ulcerative colitis
 Inflammatory condition of unknown aetiology,
o Affecting the mucosa of the large bowel.
o Always affects the rectum and extends proximally as it becomes more severe.
o Genetic susceptibility
o Environmental influences with seasonal variations in presentation rates
o Protective effect of smoking.
o Infection can cause relapses, but is not the basic cause.
o More common in northern Europe and the USA (incidence ≈ 1‱
per year)
 The classic presentation comprises:
o Bloody diarrhoea
o Urgency of defecation
o Abdominal cramps.
o Gradual onset
o Variation in severity from limited distal proctitis to aggressive fulminant pancolitis.
 Stool consistency, frequency and blood content are used to estimate severity, along with
constitutional features and signs.
 Diagnosis by:
o Endoscopic observation of mucosal changes
o Histological confirmation.
 Differential diagnosis with:
o Infectious diarrhoea
o Crohn's colitis
o Radiation colitis
o Microscopic colitis
o Drug-induced diarrhoea
 Treatment with:
o Oral and topical steroids in the acute phase
o Maintenance with
 oral and topical 5-ASA
 topical steroids
 (oral steroids + azathioprine)
o Unpredictable and common relapses
o Proctocolectomy may be indicated for severe or poorly controlled disease, steroid
dependency or complication by dysplasia or cancer.
 Ileal-pouch construction is the procedure of choice.
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A limited distal proctitis may have no constitutional disturbance and only minor symptoms,
and yet may be resistant to treatment and therefore troublesome, and vice versa.
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 Even minor disturbances of bowel habit can be incompatible with long duty periods in a small
cockpit or in an ejection-seat aircraft.
o A specialist assessment (with endoscopy) of individual cases is important for correct
disposition.
o Aviators should be grounded
 at the time of diagnosis and
 while the acute disease is treated,
 maintenance treatment established and
 estimation of the disease severity and extent.
 Return to flying may then be authorized, depending on the response and the tolerance to
maintenance treatment.
 Persisting severe and/or extended disease, or frequent relapse, or heavy therapeutic drug
burden will prevent any return to flying.
 A return to some flying duties may be allowed after proctocolectomy if general health is
restored and good continence is achieved.
Crohn's disease
 Inflammatory disease that may affect any part of the GI tract, usually in a patchy fashion:
o 30% large bowel only
o 40% small intestine only
o 30% both together
o The distal ileum is the most common single site involved.
o Transmural inflammation with frequent lymphoid aggregates.
o Non-caseating granulomata is characteristic.
o More common in smokers
o Most common in North America and Europe. (incidence ≈ 0.4‱
)
 Begins most commonly in early adult life, and follow a remitting-relapsing pattern, often with
complications.
 ≈ 100% recurrence rate @ 10 years
 80% of patients will require at least one surgical operation in the course of their disease.
 Patients with Crohn's disease have a degree of chronic ill health ➪aviation career untenable.
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Treatment:
o Corticosteroids during the active disease, but not indicated when the patient is in
remission.
o 5-ASA (Mesalazine) may be beneficial in both the active disease and maintenance of
remission.
o Azathioprine or 6-mercaptopurine may be of considerable benefit.
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The diagnosis is disqualifying for recruitment to professional aviation activity.
IRRITABLE BOWEL SYNDROME (IBS)
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Up to 50% of patients referred to general gastroenterologists have no diagnosed disease. ➪many
are given a "label" of irritable bowel syndrome.
Diagnosis of IBS is rare in aviation environment, due to absence of health-care seeking behaviour
in this population.
Markedly heterogeneous syndrome. Rome II criteria allow:
o Frequent watery stools
o Infrequent hard, pellet-like stools.
The common themes include:
o Abdominal pain
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o Relief with defecation
o Fluctuating bowel habit
o Feeling of incomplete evacuation
o Sensation of abdominal bloating.
 In aviation, if a conclusion of IBS is reached, then the symptomatic burden may be incompatible
with aircrew duties.
COELIAC DISEASE
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= Gluten enteropathy, is caused by an immunological reaction to the gluten content of cereals, ++
wheat.
o General flattening of the mucosa
 From reduction in the normal villous height/crypt depth ratio
 To total absence of villi.
Patients in adult life can present with a wide range of symptoms:
o Unexplained iron deficiency anaemia
o Diarrhoea
o Abdominal bloating
o Non-specific abdominal symptoms
o Fatigue
o General malaise.
o (Vitamin D or folate deficiency and dermatitis herpetiformis).
There are associations with:
o Diabetes I
o Autoimmune thyroid disease
o Osteopenia.
In the long term, there is a predisposition to:
o Carcinoma of the oropharynx and oesophagus
o Small bowel lymphoma.
Affects ++ Caucasians with an incidence of ≈ 0.5-1%.
Screening is possible with antibody tests tTG (tissue traznsglutaminase) with a 90% Sn and Sp.
Confirmation of the disease depends on small bowel biopsies and response to a gluten-free diet.
The diagnosis in trained aircrew is compatible with an unrestricted flying category, provided the
symptoms have resolved and there is a good compliance to the diet requirements. Motivation in
aviators is usually sufficient to ensure freedom from relapse.
GASTROINTESTINAL INFECTIONS RELATED TO TRAVEL
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At any moment, there are ≈ 107 passengers in the air. ➪A large number of people are potentially
exposed within a short period to enteropathogens of a different geographical location for which
they are immunologically unprepared.
Gastroenteritis is one of the most common causes of incapacitation of flight crews.
Travellers' diarrhoea is defined as:
o ≥ 3 unformed stools each day during or after a journey
o Or any number of such stools associated with fever, cramping abdominal pain or vomiting.
Destination and mode of travel are the major risk factors.
The pattern of pathogens is closely related to the spectrum that is endemic in the destination
country.
o The most common agent worldwide is EnteroToxigenic Escherichia Coli (ETEC).
o Shigella dysenteriae is also common in Africa and Central America.
o Campylobacter is common in Asia
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o Giardia intestinalis is most common in Eastern Europe.
o ≈ 10% of infections are due to viruses (rotavirus and Norwalk viruses)
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Individuals at high risk include:
o Those at the extremes of age
o Reduced stomach acidity
o Immune deficiency.
It is wise to avoid uncooked foods (salads ++), to take care with drinking-water sources, and to
avoid unpeeled fruit and vegetables. One should also consider the risk of ingesting water in
swimming pools and even seawater.
Flight crews should be advised to choose different items from in-flight catering, selections and
restaurant menus.
People with high personal risk may take prophylactic and treatment drugs: e.g. antibiotics
(ciprofloxacin ++).
LIVER DISEASE
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Abnormalities of liver tests are common in the aviation population (as in the general population).
o Minor ➚ of bilirubin (< 70µmol/l) occur in up to 6% of the population and may often be
related to Gilbert's syndrome and is of no clinical significance.
o Isolated ➚ of γ-glucuronyl-transferase (GGT) is likely top result from enzyme induction (OH
++ if associated ➚ MCV).
o If alkaline phosphatases (ALP) and GGT are both ➚ , then full investigation for cholestasis
or hepatic infiltration.
o Isolated ➚ of ALP is rarely hepatic in origin.
o If significant ➚ of transaminases (ALT and AST), investigations are required.
 High levels (> 103) are seen in viral and drug-induced hepatitis.
 The more common moderated elevations seen in asymptomatic people require
exclusion of:
 Chronic viral hepatitis
 Disorders of Fe and Cu metabolism
 Autoimmune hepatitis
 If all negative, a liver ultrasound will probably reveal a steatosis.
Hepatitis
 Acute hepatitis A and E are enterically transmitted diseases.
o Similar features
o Acute self-limiting hepatitis
o Do not progress to chronic liver disease or chronic carrier state.
o May be disabling for several weeks, but do not have the same longer-lasting
implications for aircrew fitness as chronic hepatitis.
 Most common causes of chronic hepatitis are:
o Viral infections (HBV, HCV)
o Autoimmune hepatitis
o Drug reactions.
o (α1-antitrypsin deficiency, Wilson's disease, haemochromatosis)
 Worldwide, patients with HBV are infected during childhood.
 The small % of patients who develop a chronic disease after acute hepatitis in adult life, are
usually immunocompromised.
 The symptoms are:
o General malaise
o fatigue
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o Arthralgia
o Right hypochondrial discomfort.
The later complications include:
o Cirrhosis
o Portal hypertension
o Hepatocellular carcinoma
Treatment consists in:
o Interferon-α, but side-effects ++
o Lamivudine, but duration ++
o ➪Unsuitable for aircrew.
Acute hepatitis C resolves completely in 15-40%
o Viral clearance can be achieved in 30-56% with antiviral treatment (pegylated
interferon-α and ribavirin)
o Aircrew will require grounding during the initial treatment (side-effects of interferon).
After 1 month and without any adverse problem, the can fly OML.
o When HCV-PCR is negative, they can return to unrestricted flying.
Autoimmune hepatitis
 May be acute or, more commonly, chronic.
 Associated with hyperglobulinaemia and other autoimmune disorders, autoantibodies of 3
groups:
o AntiNuclear Antibodies ANA and Smooth-Muscle Antibodies SMA
o Anti-liver-kidney microsomial antibodies (anti-LKM)
o Anti-soluble liver antigen/liver pancreas antibody (anti SLA/LP)
 Affects ♀ > ♂
 Presentation ranges from insidious top fulminant.
 The mainstay of treatment is immunosuppression with steroids and/or azathioprine.
 Patients stabilized on low-dose treatment may be fit for limited flying duties.
Other causes of hepatitis
 Wilson's disease — inherited disorder of Cu metabolism.
o Requires life-long treatment with chelating agents,
o Side-effects of which usually preclude fitness to fly.
 α1-antitrypsin deficiency may be the cause of liver disease in young adults.
o It's the most common genetic cause of liver disease in children,
o But usually presents with emphysema in adults.
o In the absence of effective treatment, the aviation career implications are adverse.
Haemochromatosis
 Has a very common genetic basis, but with a low phenotypic penetrance.
 The complications such as cirrhosis, cardiomyopathy, skin pigmentation, arthropathy and
endocrine disorders, can be prevented by a simple, cheap and safe treatment with venesection.
 The disease may be defined in the aviation population following detection of minor
abnormalities of liver function tests.
 Confirmation with genotyping for C282Y and H63D is widely available.
 Management of the disease should be based on clinical factors, and early diagnosis is
important ++.
 It is now commonplace for trained aircrew to continue unrestricted flying duties once
treatment is stabilized. They should not fly for 48 hours after having blood removed.
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Alcohol and the liver, and non-alcoholic steatohepatitis
 OH is the most common cause of liver injury in the Western world.
o Increasing consumption in young people suggests that death and disablement will
continue to increase.
o Alcoholic liver disease is not rare t-in the aviation community.
 Alternative causes of chronic hepatitis:
o Non-Alcoholic SteatoHepatitis NASH is now the most common cause of persistent
isolated elevation of liver enzymes (++ALT).
 NASH is associated with obesity, insulin resistance/DB-2, hyperlipidaemia and
hypertension (= metabolic syndrome).
 Red blood cell MCV is usually normal.
 In the long-term, a proportion of patients progress to cirrhosis, liver cancer and
cryptogenic cirrhosis.
o Treatment addresses the causative factors.
GALLSTONES
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Biliary colic is the only specific symptom of uncomplicated gallbladder disease.
o Occurs in < 10% of patients with gall stones.
o Unpredictable sudden onset, incapacitating, severe epigastric or right hypochondrial pain
lasting several hours.
o Multiple small stones have an unacceptable chance of producing incapacitation:
o ➪A cholecystectomy is required to allow a return to full flying duties after recovery from
surgery.
PANCREATITIS
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Acute pancreatitis is often related to gallstones, OH use or congenital abnormalities.
Serious illness, ++ incapacitating in the acute phase, with a 10% mortality rate.
Likelihood of recurrence is related to the cause.
Full recovery after and gallstone-related episode, after cholecystectomy, may be compatible with
a return to unrestricted flying duties.
Recurrent or chronic pancreatitis will lead to permanent grounding.
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