Environment

Systemic radiation effects

1. Acute effects
   • Haemopoietic syndrome
     • Severe lymphopenia
     • Thrombocytopenia
     • No new cells are formed in the marrow
   • Gastrointestinal syndrome
     • Vomiting
     • Intractable bloody diarrhoea follows, with dehydration, secondary infection and sometimes death
   • CNS syndrome
     • Nausea, vomiting, disorientation and coma.
     • Death due to cerebral oedema can follow
   • Radiation dermatitis
     • Skin erythema, purpura, blistering and secondary infection occur.
     • Total loss of body hair is a bad prognostic sign

2. Delayed effects
   • Infertility
   • Teratogenesis
   • Cataract
   • Neoplasia:
     • Acute myeloid leukaemia
     • Thyroid
     • Salivary glands
     • Skin
     • Others

* Kumar and Clark’s Clinical Medicine, 9th Edition Box 5.5

Temperature-related disorders are:

• Hypothermia
• Heat cramps
• Heat syncope
• Heat exhaustion
• Heat stroke.

* Pre-exam preparation for medicine, HN Sarker

Figure: Clinical features of abnormal core temperature. The hypothalamus normally maintains core temperature at 37°C.

* Figure: Davidson’s Principles and Practice of Medicine, 22nd edition Page: 104

When core temperature falls below 35°C, it is called hypothermia.

* Pre-exam preparation for medicine, HN Sarker

Common causes are:

• Immersion in cold water
• Exposure to extreme climates such as during hill walking
• Hypothyroidism
• Glucocorticoid insufficiency
• Stroke
• Hepatic failure

* Pre-exam preparation for medicine, HN Sarker

Clinical features are:

• Depressed conscious level
• Dehydration
• Confusion
• Muscle stiffness
• Ice cold and pale
• Bradycardia

* Pre-exam preparation for medicine, HN Sarker

ECG may show characteristic J waves, which occur at the junction of the QRS complex and the ST segment.

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 104

Treatments are:

1. Resuscitation-maintain ABC
2. Rewarming the patient in a controlled manner
3. Treatment of associated hypoxia (by oxygenation and ventilation if necessary), fluid and electrolyte disturbance and dysrhythmias if present.

 * Pre-exam preparation for medicine, HN Sarker

Heat-related illnesses are:

• Heat cramps
• Heat syncope
• Heat exhaustion
• Heat stroke.

* Pre-exam preparation for medicine, HN Sarker

Heat stroke occurs when the core body temperature rises above 40°C and is a life-threatening condition.

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 106

 

• The symptoms of heat exhaustion (dehydration, tachycardia, irritability, fatigue, headache, weakness) progress to include headache, nausea and vomiting.
• Neurological manifestations include –
  • a coarse muscle tremor and confusion,
  • aggression or loss of consciousness.
• The patient’s skin feels very hot, and sweating is often absent due to failure of thermoregulatory mechanisms.

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 106

Treatments are:

1. The patient should be resuscitated with rapid cooling by spraying with water, fanning, and ice packs in the axillae and groins.
2. Cold crystalloid intravenous fluids are given but solutions containing potassium should be avoided.
3. Over-aggressive fluid replacement must be avoided, as it may precipitate pulmonary oedema or further metabolic disturbance.
4. Appropriate monitoring of fluid balance, including central venous pressure, is important.
5. Once emergency treatment is established, heat stroke patients are best managed in intensive care.
6. Clear advice to avoid heat and heavy exercise during recovery is important.

 * Davidson’s Principles and Practice of Medicine, 22nd edition Page: 106

Complications include –

• hypovolaemic shock,
• lactic acidosis,
• disseminated intravascular coagulation,
• rhabdomyolysis,
• hepatic and renal failure, and
• pulmonary and cerebral oedema.

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 106

Investigations for complications include –

• routine haematology and biochemistry,
• coagulation screen,
• hepatic transaminases (aspartate aminotransferase and alanine aminotransferase),
• creatine kinase and
• chest X-ray

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 106

In heat stroke, core temperature is >40°C and sweating is absent but in heat exhaustion, core temperature is > 37–40°C and sweating is present.

* Pre-exam preparation for medicine, HN Sarker

Hyperthermia is an increase in body temperature over the body’s thermoregulatory set-point, due to excessive heat production and/or insufficient thermoregulation. It is not a fever.

Hyperpyrexia is a fever with an extreme elevation of body temperature greater than or equal to 41.5°C (106.7°F).

* Pre-exam preparation for medicine, HN Sarker

* Pre-exam preparation for medicine, HN Sarker