# Environmental Diseases and Injuries

## Environmental Diseases

In the following pages the most common environmental diseases will be presented. They will be divided according to the causative factor.

## Basic Physics Definitions

Definitions below will be mentioned during the whole chapter; for that reason, it is important to emphasize how to understand the basics of some environmental diseases, especially those related to high altitude, flight, and diving. ,

• 1.

Dalton’s Law: This law states that the total pressure of a mixture of gas is equal to the sum of the partial pressure of each gas in the mixture. It explains hypoxia.

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Total pressure = P 1 + P 2 + P 3 + … + P n

• 2.

Boyle’s Law: This states that at constant temperature, the volume of a gas is inversely proportional to the pressure to which it is subjected. It explains the trapped gases phenomenon.

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P 1 / P 2 = V 2 / V 1

• 3.

Henry’s Law: This law states that the amount of gas dissolved in solution varies directly with the pressure of that gas over the solution. It explains the nitrogen movement in decompression sickness (DCS).

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P 1 / P 2 = A 1 / A 2

• 4.

Graham’s Law: Known as the law of gaseous diffusion, this law states that “A gas will diffuse from an area of high concentration to an area of low concentration.”

## High-Altitude Medicine

In high-altitude medicine, it is necessary to know how altitude is divided to explain the different expected physiologic findings in each range. Although in the literature it is possible to find different classifications, for the purposes of this subject, the classification proposed by Gore et al. will be used (see Table 9.1 ).

Table 9.1

Classification of altitudes

Altitude Range in Meters Over Sea Level Range in Feet Over Sea Level
Sea level 0–1000 0–3280
Low altitude 1000–2000 3280–6561
Intermediate altitude 2000–3000 6561–9842
High altitude 3000–5000 9842–16,404
Extreme high altitude 5000–8848 16,404–29,028

Data from Gore CJ, Clark SA, Saunders PU. Nonhematological mechanisms of improved sea-level performance after hypoxic exposure. Med Sci Sports Exerc. 2007;39(9):1600–1609.

Exposure to high altitude can cause the exposed subject to experience a wide range of signs and symptoms that may be determined by the altitude, the subject’s fitness, previous medical conditions, and previous acclimatization. Related conditions at different ranges of altitude are known as high-altitude illnesses.

• 1.

Acute mountain sickness (AMS)

• a.

Definition: condition that affects individuals who ascend rapidly to high altitude.

• b.

Signs and symptoms:

• i.

Symptoms may be present between 6 and 24 hours after ascending.

• ii.

• iii.

Signs: During the physical examination, it is possible not to find signs, and the diagnosis is based on clinical history. However, it is possible to find peripheral edema, crackles in the chest, and early speech impairment. ,

• c.

Treatment: most cases of AMS get better within 24 to 48 hours without treatment. However, some may progress to acute pulmonary edema or cerebral edema, and treatment depends on symptoms and clinical features ( Table 9.2 ).

Table 9.2

Treatment in acute mountain illness

Procedure Dose Reference
Stop ascent/rest
Paracetamol 500–1000 mg
Ibuprofen 400–600 mg
Oxygen 2–4 L/m (night)
Cerebral edema
Immediate descend 300–500 m
Acetazolamide 125–250 mg every 8–12 h
Dexamethasone 4 mg every 6 h orally
Portable hyperbaric chamber 193 mbar during 1 h
Acute mountain Sickness (AMS)
Mild AMS
Stop ascent/rest 24 h
Paracetamol 1 g every 6 h
Ibuprofen 400 mg every 8 h ,
Acetazolamide 125–500 mg every 12 h
Moderate/Severe AMS
Descend 300–500 m
Paracetamol 1 g every 6 h ,
Ibuprofen 400 mg ,
Dexamethasone 4 mg PO, IM, IV ,
Oxygen 1–2 L/m ,
Portable hyperbaric chamber 193 mbar during 1 h ,
IM, Intramuscularly; IV, intravenously. Please verify drugs avaliability in your country or equivalents.

• 2.

High altitude cerebral edema (HACE)

• a.

Definition: severe presentation of AMS that affects neurologic function. It may affect unacclimatized individuals that ascend over 3000 m.

• b.

Signs and symptoms

• i.

Symptoms: Usually, symptoms of HACE are preceded by AMS symptoms, and they are present within 24 to 36 hours. Symptoms include headache, nausea, vomiting, photophobia, loss of appetite, irritability, bizarre and irrational behavior, and blurred vision.

• ii.

Signs: ataxia, irrationality, hallucinations, clouding consciousness, brisk deep-tendon reflexes, diplopia, tachycardia, and cyanosis.

• c.

Treatment: descend to lower altitudes as soon as possible; supply oxygen; dexamethasone 8 mg initial doses followed by 4 mg every 6 hours.

• 3.

High-altitude pulmonary edema (HAPE)

• a.

Definition: severe presentation of AMS that affects respiratory function. It can affect unacclimatized individuals that ascend over 2000 to 7000 m.

• b.

Symptoms and signs: The subject usually presents with symptoms of AMS and may then present with symptoms of HAPE. ,

• i.

Symptoms: shortness of breath, lethargy, chest pain, dry cough, nocturnal dyspnea, hemoptysis, insomnia, dizziness.

• ii.

Signs: tachycardia, tachypnea, crackles at lung bases, cyanosis, respiratory distress, orthopnea, bubbling respirations, coma.

• c.

Treatment: descend as soon as possible; supply oxygen; dexamethasone initial doses 8 mg, and then 4 mg every 6 hours; nifedipine 20 mg slow release.

• 4.

Other medical conditions at high altitude

• a.

Neurovascular disorders

At high altitude, some neurologic signs unrelated to AMS, HAPE, or HACE have been reported, some of which are transient. This range of conditions has been associated with a vascular origin (spasm, thrombosis, embolus, or hemorrhage); whereas others may be neurologic disorders or of unknown origin. Basnyat et al. list neurovascular disorders that are not included in AMS ( Box 9.1 ).

Box 9.1

Neurovascular Disorders Not Included in Acute Mountain Sickness

Transient ischemic attacks and strokes

Cerebrovascular attack

Migraine

Cerebral venous thrombosis

Subarachnoid hemorrhage

Seizures, epileptic fits

High-altitude syncope

Transient global amnesia

Delirium at high altitude

Cranial nerves palsies

Ophthalmological problems

Possible coagulation problems

Basnyat B, Wu TY and Certsch JH. Neurological conditions at altitude that fall outside the definition of altitude illness. High Alt Med Biol . 2004;5:171–179.

• b.

Dry eye syndrome: a common finding in climbers and trekkers. Its origin is a reduced production of tears with altitude where dry air, windy conditions, and glare are present.

• i.

Symptoms: irritation of eyes, light sensitivity, blurred vision, and burning sensation.

• ii.

Prevention: use of goggles with protection Ultraviolet A (UVA)-Ultraviolet B (UVB); tear-substitute eye drops.

## Heat Stress and Illness

Definition: temperature-related illnesses encompassing a broad spectrum of symptoms that can lead to death if not treated correctly. Heatstroke affects people trapped in hot conditions with little or no air circulation; it mostly affects those with medical conditions, those using pharmacological treatments, or those unaware of the physiologic effects of heat.

High temperatures are thought to cause at least 70,000 deaths/year in Europe, with an average mortality of 40 people every year in the United Kingdom and 200 each year in the United States from heatstroke. ,

Risk factors: A broad spectrum of factors increase the probability of heat illness :

• Ambient temperature above 35 o C and relative humidity over 60%

• Overweight and obesity

• Sleep deprivation

• Overexertion syndrome

• Medical conditions

• Fever

• History of cardiovascular disease

• Seizures

• Drug abuse

• Medication

• Beta-blockers

• Angiotensin converting enzyme (ACE) inhibitors

• Furosemide—hydrochlorothiazide

• Antihistamines

• Antispasmodics

• Alpha-agonists

• Stimulants

• Burns

• Muscular exertion

• Dehydration

• 1.

Heat stroke

• a.

Definition: condition produced when heat exchange mechanisms fail to dissipate heat, and abnormal mental status and neurologic function impairment begin to set in. This is a medical emergency, and treatment must be given immediately to prevent death, using different cooling measures. ,

• b.

Signs and symptoms , :

• i.

Increase in core body temperature above 40.5 o C

• ii.

Altered mental status and loss of motor coordination

• iii.

Increase in respiratory, pulse, and heart rate

• iv.

Slowly decreasing sweating capacity

• v.

Arterial pressure drop

• c.

Treatment

• i.

Cooling measures ,

• ii.

Secure airway, oxygen, and administer only intravenous (IV) fluids (2 L of normal saline solution, children 20 mL/kg with an initial bolus).

• iii.

Use cold packs on neck, chest, axillae, abdomen, and inguinal region.

• iv.

Use benzodiazepines if needed to sedate patient (midazolam 0.2 mg/kg intramuscular [IM]).

• v.

Wet the patient with ambient-temperature water and ventilate for cooling.

• vi.

Treat shivering with chlorpromazine or midazolam to prevent muscle heat production.

• vii.

Core body temperature must be checked regularly, making sure cooling efforts are maintained until a body temperature of 38 o C is reached.

• viii.

Evacuate patient via air or land.

• 2.

Heat exhaustion

• a.

Definition: condition presented when core body temperature is below 38 o C. Patient presents with nonspecific symptoms such as headache, weakness, malaise, nausea and/or vomiting. ,

• b.

Diagnosis

• i.

Clinical diagnosis supported by nonspecific symptoms, and core body temperature is mildly elevated.

• ii.

Rapid heart and respiration rate

• iii.

Orthostatic hypotension

• iv.

Sweating

• v.

Normal mental status, and neurologic examination is normal

• c.

Treatment

• i.

Decrease heat gain, moving patient to the shade and well-ventilated area

• ii.

Remove clothing to improve heat loss

• iii.

Administer at least 1 to 3 L of oral fluids initially.

• iv.

Place cool packs on the neck, chest wall, abdomen, and axillae and ventilate the patient, being careful not to leave ice packs in direct contact with skin for too long, to avoid frostbite.

• v.

Evacuation or inpatient treatment often not necessary.

• 3.

Heat edema

• a.

Definition: condition produced by increases in hydrostatic pressure along with a hyperhemodynamic physiologic start of heat stress that produces peripheral edema in a hot environment in unacclimatized patients. ,

• b.

Diagnosis:

• i.

Edema with or without fovea might be present, especially in lower extremities

• ii.

Facial edema

• c.

Treatment

• i.

This is a self-limited condition and supportive physical measures may be given to provide comfort

• ii.

• 4.

Miliaria rubra

• a.

Definition: skin reaction produced after being exposed to warm and humid climates. It produces epidermis desquamation that may last 7 days. ,

• b.

Diagnosis

• i.

Eczema

• ii.

Pruritus

• iii.

Erythematous papules

• iv.

Desquamation of the skin from 7 to 10 days

• c.

Treatment

• i.

Dry and cool the affected skin

• ii.

• 5.

Heat syncope

• a.

Definition: loss of consciousness produced by lengthy sun exposure either standing or with physical activity , ,

• b.

Diagnosis

• i.

Syncope when risk factors are present (ambient temperature >35°C, humidity >60%)

• c.

Treatment

• i.

Patient must be treated following the initial CAB approach (Compressions-Airway-Breathing)

• ii.

Assess traumatic lesions secondary to syncope

• iii.

Make sure Trendelenburg position is adopted

• iv.

Cool the patient

• v.

Administer at least 1 to 2 L of hydration fluids

• vi.

If the patient does not recover, must be deferred for treatment because of heatstroke potential or other causes of loss of consciousness

• 6.

Heat cramps

• a.

Definition: When exposed long enough to heat, dehydration sets in and electrolyte imbalance may lead to heat cramps. Those who are not acclimatized to heat or profuse sweaters may experience them. , ,

• b.

Diagnosis

• i.

Spasmodic muscle cramps

• ii.

Pain

• iii.

Recurrence may be triggered by manipulation of the muscle.

• c.

Treatment

• i.

Move patient to a cooler environment

• ii.

Rehydration using balanced electrolyte solutions

• iii.

Stretching the muscles involved

• 7.

Dehydration and hyponatremia

• a.

Definition: Hyponatremia is set when serum sodium is less than 130 mEq/L. It can be confused with water intoxication from drinking large amounts of hypoosmolar fluids. Also, it is easily confused with heat illness in which the core body temperature is increased; in hyponatremia, body temperature is usually normal. ,

• b.

Diagnosis , ,

• i.

Weakness

• ii.

Painful muscle spasmodic cramps

• iii.

Hyporexia

• iv.

Nausea and vomiting

• v.

Altered mental status

• vi.

Core body temperature usually below 38°C

• vii.

Seizures

• viii.

Serum sodium level below 130 mEq/L (to confirm diagnosis)

• c.

Treatment and prevention

• i.

If intolerant to drinking oral fluids, IV line must be placed with normal saline solution 500 to 1000 mL/h

• ii.

If not vomiting, oral rehydration solutions can be given.

• d.

Prevention: Wet bulb globe temperature (WBGT) must be calculated considering humidity and ambient temperature. Normal thermometers are not predictors of heat illness because these are not capable of measuring humidity. An alternative to WBGT equipment in the field is to use a psychrometer. ,

• e.

Acclimatization: takes different times in each individual, with a range of 10 to 14 days. The rate of physiologic change depends on body composition, ambient temperature, and preexisting medical conditions. , ,

• i.

Benefits of acclimatization include lower heart rate, increase in blood flows, sweat production, increase in plasma proteins (preventing edema), reduced core temperature, fluid and sodium loss, and improved renal reabsorption of sodium and water by means of aldosterone adequate equilibrium. , ,

• ii.

Sweat rate improves heat loss, and changes appear from day 1 to day 5, increasing from 0.5 to 3 L/h coupled with exercise improves acclimatization, but this implies fluid intake must be enough for this mechanism to be effective. ,

## Acute Sunburn

• 1.

Definition: Sunburn is an acute cutaneous inflammatory reaction that follows excessive exposure of the skin to ultraviolet radiation (UVR) from the sun. Long-term adverse health effects of repeated exposure to UVR are well described, and its classification comes from superficial or first-degree burns. The main injury responsible for sunburn is direct damage to DNA by UVR, resulting in inflammation and apoptosis of skin cells; this inflammation causes vasodilation of cutaneous blood vessels.

• 2.

Diagnosis: The acute inflammatory response is greatest 12 to 24 hours after exposure. The representative erythema usually occurs 3 to 4 hours after exposure, with peak levels at 24 hours, and resolves over 4 to 7 days, usually with skin scaling and peeling.

• a.

Warmth

• b.

Tenderness

• c.

Edema

• d.

Blistering (severe cases)

• e.

Pain

• 3.

Treatment: Most sunburns, while painful, are not life threatening, and treatment is primarily symptomatic. Nonsteroidal antiinflammatory drugs (NSAIDs) may relieve pain and inflammation, especially when given early. Cool soaks with water or aluminum acetate solution also provide temporary relief. Additionally, fluid replacement (oral or IV) for severe erythema or concomitant fluid loss.

## Photo Protection

• 1.

Sunscreens: Most healthcare providers and the American Academy of Dermatology recommend:

• a.

Use a sunscreen with an SPF of 30 or greater on exposed skin.

• b.

Use a sunscreen that protects against both UVA and UVB radiation.

• c.

You may need a higher SPF if you are fair-skinned, if you will be in the sun for a long time, or if you anticipate intense sun exposure. ,

• 2.

Clothing

In addition to sunscreen, clothing can be an excellent form of sun protection. The most important determinant is tightness of the weave. Consider covering exposed skin with a wide-brimmed hat, long-sleeved shirt, and long pants. A hat made of tightly woven material can provide shade for the face, ears, and back of the neck. Clothing made from tightly woven dark fabrics tends to provide greater protection than light-colored fabrics. Some manufacturers have sun-protective clothing with SPF. , Some countries, such as Australia, have standards dealing with solar UVR protection, namely the Sunscreen Standard (AS2604) and the Sunglass Standard (AS1067). With these standards, there is the ability to impose substantial penalties for noncompliance.

• 3.

Sunglasses

Many studies indicate that long-term exposure to short-wavelength visible light, UV radiation, and lower wavelength visible light may be hazardous and cause increased risk of certain ocular pathologies such as cataracts and maculopathy, which are a concern for military and civilian aircrews. Pilots may be exposed to solar radiation for long periods of flight where UV radiation is known to be significantly greater than at sea level. Aircraft windshields should have a standard for optical transmission, particularly for short-wavelength radiation. Any sunglasses used must follow national quality standards. However, a substantial number of commercially available sunglasses are being manufactured without apparent regard for these potential hazards. Aircrew have to wear certificated sunglasses that ensure protection from UVA and UVB radiation.

## Scuba Diving Disorders

Scuba diving implies that the body is exposed to a high-pressure environment. Associated disorders can be divided into two categories : (1) conditions derived from gas expansion according to Boyle’s Law and (2) liberation of a gas phase from tissues following Henry’s Law.

## Ear and Sinus Barotrauma

• 1.

Definition: Described as the most common injury for divers (30%), it is defined as tissue injury as a consequence of a failure in equalizing pressure in gas-filled spaces (middle ear and paranasal sinuses). Ear barotrauma is present mainly during ascent when the Eustachian tube cannot equalize pressure, whereas sinus barotrauma is caused by a blockage of the sinus ostium.

• 2.

Diagnosis: main symptom is pain. Facial pain with epistaxis is common for sinus barotrauma, whereas ear pain is common for ear barotrauma; sometimes vertigo and conductive hearing loss are present.

• 3.

Clinical findings:

• a.

Ear barotrauma: injection of the tympanic membrane, hemotympanum, and/or ruptured tympanic membrane

• b.

Sinus barotrauma: mucosal edema, facial pain

• 4.

Treatment: decongestants, analgesics and antiinflamatory drugs

## Pulmonary Over-Inflation Syndromes

• 1.

Definition: syndrome that is produced by the expansion of gas during ascent (Boyle’s Law) derived from breathing additional gas, during scuba diving. It appears when the inhaled gas is not exhaled during ascent, thus mechanical forces can disrupt lung parenchyma.

• 2.

Signs and symptoms

• a.

Mild features

• i.

Symptoms: hemoptysis and dyspnea

• ii.

Signs: tachypnea, pneumomediastinum or pneumothorax, gas embolism

• b.

Severe features: (<4%): collapse, loss of consciousness, hemiparesis, confusion, loss of coordination, apnea, and cardiac arrest

## Decompression Sickness in Scuba

• 1.

Definition: syndrome produced by gas liberation (nitrogen) from tissues to blood by a reduction in barometric pressure (Henry’s Law). Released nitrogen forms bubbles that depending on their localization produce a range of signs and symptoms that are described below. ,

• 2.

Bends: This is the most common symptom and the earliest. Bends is defined by pain, mainly in the large joints. It affects hips, elbows, and knees mainly; however, pain can be present in other joints. Bends occurs within 6 hours after exposure, but it can be found 12 to 24 hours after. ,

• 3.

Chokes: Also known as cardiovascular DCS, this is caused by high venous gas embolism in the pulmonary artery. Symptoms include cough, shortness of breath, substernal chest pain, and sometimes collapse. ,

• 4.

Skin bends: Also known as creeps, skin bends are caused by transcutaneous passage of nitrogen bubbles. Cutis marmorata (diffuse/blotchy rash) is another form of skin DCS. It is caused by extravasated blood from cutaneous vessels derived from endothelium injury caused by bubbles, and it may disappear after 12 hours. ,

• 5.

Lymphatic DCS: This appears when a bubble blocks lymphatic vessels. Its symptoms include lymphedema of the affected area. ,

• 6.

Neurological DCS: The wide range of symptoms of this condition makes diagnosis difficult. Symptoms depend on the area affected by the bubbles. Headache, paresthesias, paralysis, vertigo, loss of consciousness may be found. ,

• 7.

Treatment: recompression in hyperbaric chamber breathing 100% oxygen; endovenous liquids. ,

A summary of Scuba diving disorders and their primary treatment is presented in Table 9.3 , and a comparison of diving and altitude DCS is seen in Table 9.4 .

Table 9.3