Sports and the Environment

Sports and the Environment
	Donald Kuah

		Temperature Extremes The human body attempts to maintain its core temperature (often measured by rectal temperatures) within the normal range of 36.1 to 37.80 C by a balance between heat production/gain and heat loss.
		Heat Illnesses/Hyperthermia
	Classification	Heat illnesses are a spectrum of clinical presentations classified into mild, moderate  or severe (Fig. 4) Mild (heat fatigue, heat cramps, heat syncope) Moderate (heat exhaustion). Severe (heat stroke) > 410 C. Reduced level of consciousness.
	Treatment	Rest, ice, massage for cramps; rapid cooling (with IV fluids) for severe cases. These include hypotension, arrhythmias, myocardial infarct, cardiac failure,
	Complications	convulsions, cerebro-vascular events and coma, gastrointestinal bleeding, liver damage and renal failure, and other rhabdomyolysis (breakdown of skeletal muscle membrane) and DIC.
	Prevention	Wear appropriate cool, light coloured clothing. Stay well hydrated (Fig. 5). Adequate fitness preparation and heat acclimatisation if appropriate. Avoid exercise in extreme heat (and humidity). Cold Stress/Hypothermia Those at risk of hypothermia include alpine and cross country skiers, endurance, adventure and water sports participants.
	Classification	Hypothermia can be classified as mild, moderate, or severe.: Mild (35-37° C): Cold extremities, shivering, tachycardia, tachypnoea, urinary urgency, slight incoordination. Moderate (32-34° C): Increased incoordination and clumsiness, reduced shivering, slurred speech, dehydration, fatigue, amnesia, drowsiness, and poor judgement. Severe (<32° C): Total loss of shivering, inappropriate behaviour, reduced level or loss of consciousness, muscle rigidity, hypotension, pulmonary oedema, extreme bradycardia, and cardiac arrhythmias (especially ventricular fibrillation, VF).
	Management	This involves general life support measures (fluids, nutrition, cardiac support), minimising further heat loss, and re-warming. Monitor core temperature and vital signs. In severe hypothermia, there must be gentle and minimal handling of the patient for fear of VF arrest. Re-warming may be passive, external active or internal active (controversial topic) (Fig. 6).
	Prevention	Wearing appropriate clothing Keep well hydrated and nourished. Adequate planning (Fig 7). Appropriate fitness level. Avoid exercising to exhaustion.
		Altitude Medicine The decrease in barometric pressure and air density which accompanies increases in altitude have both advantages and disadvantages for athletes. Sprinters, are aided by the reduced air resistance whereas endurance athletes are hampered from the lower oxygen concentration (Fig 8).
	Clinical Conditions	Mountain Sickness. Usually a temporary condition effecting the first 2 or 3 days of a rapid ascent over 2000m. Features include headache, dizziness, nausea, vomiting, insomnia, and syncope. Acetazolamide may reduce the symptoms and if the symptoms are severe, return to lower altitudes. Altitude cerebral oedema. This is a rare condition which usually occurs on rapid ascents above 4000m altitude. Symptoms include headache, confusion hallucinations, and reduced level of consciousness or coma. Management involves urgent return to low altitude, oxygen therapy and intravenous corticosteroids. Altitude pulmonary oedema. This life threatening condition occurs in the first 3 days of ascent above altitudes of 2000m and manifests with symptoms of shortness of breath, coughing and copious frothy sputum. Retinal haemmorhage. Small retinal haemorrhages may occur above altitudes of 4000m.
	Prevention	Rapid ascents to moderate and high altitudes should be avoided. Altitude acclimatisation improves pulmonary ventilation, capillarization and increases red blood cell mass and haemoglobin (Fig. 9). Awareness and recognition of early symptoms and signs.
		Underwater Medicine There are various medical considerations and problems in the popular sport. In underwater diving the most common cause of death is drowning (Fig. 10) whilst the most common problem is decompression sickness. In sea water, pressure increases by one atmosphere with each 10m increase in depth. Gas filled spaces undergo their greatest volume changes near the surface. Hence shallow dives may not be safer than deeper dives as is commonly thought.
		Decompression Sickness (DCS) DCS involves a wide variety of multi-organ symptoms as a result of the formation of nitrogen bubbles in either the body’s tissues or blood during ascent. These symptoms can occur anytime in the first 24 hours following ascent.
	Clinical types	Intravasular DCS: Plasma volume is lowered and increased viscosity causes coagulation abnormalities. Neurological DCS: Involves a wide spectrum of central and peripheral nervous system problems which are due to the increased affinity of nitrogen to myelin. Cardiorespiratory DCS: Dyspnoea, chest pain and cough (the chokes) may progress to cardiac arrest if emergency treatment is not instituted. Musculoskeletal DCS: This is the most common form of DCS and presents as joint pains which may rarely lead to avascular necrosis. Cutaneous DCS: Pruritis and measles like rash, 'Cyanotic marbling’ is a sign of severe DCS. Gastrointenstinal DCS: Abdominal cramps, nausea and anorexia.
	Treatment	Early treatment can reverse established symptoms and signs and involves 100% oxygen, intravenous fluids, and the appropriate transport of the patient for recompression (Fig. 11).
		Barotrauma (BT) Barotrauma refers to the injury caused by pressure imbalances between gas spaces in the body and adjacent body tissues or fluids.
	Clinical types	Middle ear BT. The most common with bleeding into the middle ear and tympanic membrane rupture. All cases require audiograms, analgesia, decongestants ± antibiotics. Inner ear BT. Presents as persisting vertigo and/or tinnitus. Sinus BT. Presents as blood in the face mask (Fig. 12) and pain but is not usually serious. Pulmonary BT. This is the second most common cause of diving deaths and is encountered (after rapid or uncontrolled ascent). Includes arterial gas embolism, pneumothorax, surgical emphysema, or pulmonary infarcts. Give 100% oxygen and nurse horizontally if gas embolism is suspected (to avoid air bubbles going to the brain). Stabilise of pneumothorax (if present) and recompress.     Prevention of diving accidents         Pass accredited diving medical.         Appropriate training certification and safety procedures.         Current safety equipment regularly checked