Burn to the Back of His Hand from an Unknown Substance
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• MRCS Part A - Sep 2019 Exam A 32-year-old man attends the Emergency Department having sustained a chemical burn to the back of his hand from an unknown substance. Which one of the following statements regarding chemical burns is correct? Acids cause more damage to deeper tissues than alkali burns Alkali burns are more painful than acid burns Dry powder should be immediately irrigated with copious amounts of water Neutralising agents should be the first-line of treatment in cement burns Systemic calcium may be required in the treatment of burns due to hydrofluoric acid Explanation Systemic calcium may be required in the treatment of burns due to hydrofluoric acid Hydrofluoric acid penetrates tissues deeply, and even small burns can cause fatal systemic toxicity. Copious lavage with water and treatment with topical calcium gluconate gel is the necessary first step. Systemic calcium may be required as hydrofluoric acid sequesters calcium following the burn. Acids cause more damage to deeper tissues than alkali burns Alkali burns are more serious than acid burns, as alkalis penetrate more deeply. Alkali burns are more painful than acid burns Acid burns are generally more painful than alkali burns; in alkali burns, the onset of pain is delayed, which often postpones first aid and so leads to more tissue damage. Dry powder should be immediately irrigated with copious amounts of water Both acid and alkali burns should be immediately flushed away with large amounts of water for at least 20 to 30 min. If dry powder is present on the skin, it should be brushed away before irrigation with water. Neutralising agents should be the first-line of treatment in cement burns In cement burns, neutralising agents have no advantage over water lavage, because reaction with the neutralising agent may itself produce heat and cause further tissue damage. 1442 • • • • • • • • • • • • • • • MRCS Part A - Sep 2019 Exam An 18-month-old child is brought to the paediatric burn service having pulled a cup of hot coffee off the kitchen table, tipping it on himself. Which one of the following statements is characteristic of deep dermal burns? They are characterised by the presence of escharThey are more painful than superficial burnsThey do not blisterThey have a blotchy red colourationThey heal spontaneously by epithelialisation within 14 days Explanation They have a blotchy red colouration Deep burns may be either deep dermal or full thickness. Deep dermal burns may have some blistering, but the base of the blister demonstrates the characteristic of the deeper, reticular dermis often showing a blotchy red colour. This colour is due to the extravasation of haemoglobin from destroyed red cells leaking from ruptured blood vessels. They are characterised by the presence of eschar Eschar (coagulated dead skin with a leathery appearance) is a feature of full thickness burn. They are more painful than superficial burns The dermal nerve endings are also situated at the level of the deep dermis (reticular) and, in such burns, sensation to pinprick will be lost. They are less painful than superficial burns (in which the nerve endings are intact). They do not blister Deep dermal burns can have some blistering. They heal spontaneously by epithelialisation within 14 days Deep dermal burns will not heal spontaneously by epithelialisation. They heal after a prolonged period, usually by secondary intention. Healing is associated with wound contraction and scarring. MRCS Part A - Sep 2019 Exam A 25-year-old man presents to the burn out-patient clinic with excess hypertrophic scarring over his chest following a severe burn. Which one of the following is a characteristic of hypertrophic scarring? It is characteristically seen over the extensor surfaces It characteristically extends beyond the margins of the original scar It has a strong genetic predisposition It is characteristically seen in deep dermal burns Treatment rarely improves the appearance Explanation It is characteristically seen in deep dermal burns A hypertrophic scar is a form of excessive healing resulting from overproduction of all components of the healing process, including fibroblasts, collagen, elastin and proteoglycans. The incidence of hypertrophic scars is highest in: • Wounds crossing flexor surfaces • Wounds crossing tension lines • Areas of excessive skin (wound) tension and movement • Deep dermal burns • Wounds left to heal by secondary intention (more than 3 weeks). It is characteristically seen over the extensor surfaces Hypertrophic scarring is more commonly seen over the flexor surfaces. It characteristically extends beyond the margins of the original scar Hypertrophic scars are confined to the margins of the original scar while keloids outgrow the wound (scar) area. It has a strong genetic predisposition Hypertrophic scars do not have a genetic predisposition; keloids are thought to have a genetic link. Treatment rarely improves the appearance Hypertrophic scars respond to appropriate conservative treatment, including topical steroids and compression therapy, and subside with time. 1470 • MRCS Part A - Sep 2019 Exam A 34-year-old woman is admitted to the Intensive Care Unit (ICU) with 45% total body surface area (TBSA) burns to her head, trunk and perineum, having accidentally set herself on fire at a bonfire party. For which one of the following complications of severe burns should you be vigilant given this patient’s injuries? Acute appendicitisCushing’s ulcers Myoglobinuria Hypokalaemia Sepsis Explanation Sepsis Major burns are associated with numerous complications, as are other forms of major trauma. Burns are extremely susceptible to infection, which can lead to sepsis due to a patient’s immunocompromised state. Acute appendicitis There is no evidence to suggest acute appendicitis as a complication of severe burns. Cushing’s ulcers Curling’s (not Cushing’s) ulcers are stress ulcers related to major burns. A Cushing’s ulcer is a gastric ulcer associated with raised intracranial pressure. Myoglobinuria Muscle loss/injury due to electrical (not thermal) burns may lead to myoglobinuria. Hypokalaemia Potassium levels tend to rise due to cellular damage and sodium levels can be raised or lowered due to excessive or inadequate fluid resuscitation. 1909 • • Contact Us • MRCS Part A - Sep 2019 Exam A 23-year-old man is admitted to the intensive care unit with 60% burns. He remains very unstable for a few days requiring central line and arterial line access. Which one of the following is a systemic effect of this type of trauma? Glycogenesis Hypervolaemia Hypothermia Immunosuppression Reduced metabolic rate Explanation Immunosuppression Nearly every organ system in the body is affected after a significant burn. This result is due to alterations in the release of inflammatory mediators and neural stimulation. Immunosuppression is due to depression of many facets of the immune mechanism, both cellular and humoral. This situation explains why infection is still the leading cause of mortality in burn victims. Glycogenesis Burn injury results in a hypermetabolic state, caused by the secretion of the stress hormones, including cortisol, catecholamines and glucagon, which stimulates glycogenolysis not glycogenesis. Hypervolaemia Hypovolaemia is a characteristic feature of major burns that is principally due to loss of protein and fluid into the interstitial space. The lungs frequently suffer from changes of the post-burn systemic inflammatory response (adult acute respiratory distress syndrome) even in the absence of inhalation injury. Hypothermia Burn injury results in a hypermetabolic state, caused by the secretion of the stress hormones, including cortisol, catecholamines and glucagon. In addition, there is suppression of, or resistance to, anabolic hormones (growth hormone, insulin and anabolic steroids). Clinically these changes are expressed as tachycardia and hyperthermia. Reduced metabolic rate As discussed, burn injury results in a hypermetabolic state, caused by the secretion of the stress hormones, including cortisol, catecholamines and glucagon. 1912 • MRCS Part A - Sep 2019 Exam A 60 kg man suffers 20% burns. He is referred to the regional burns centre. What is the estimated volume of intravenous fluid replacement that should be administered in the first 8 h from the time of the burn using the Parkland formula? 1000 ml 1200 ml 2400 ml 4800 ml 5000 ml Explanation 2400 ml Intravenous fluids should be administered if burns of greater than 15% in adult or 10% in paediatric patients are present. The rate of fluid administration ultimately employed is dependent on clinical indices such as urine output, capillary refill and peripheral perfusion, central venous pressure and core:peripheral temperature differentials. Various formulas are available for estimating initial rates of intravenous fluid replacement in burns victims. These initial rates of fluid administration are then modified based on clinical response. The most commonly used is as follows: • Parkland formula: Volume = 4 ml x weight (kg) x % TBSA (full or deep partial thickness) in first 24 h from time of burn. • Half of this calculated volume (crystalloid) should be administered in the first 8 h and the remainder administered in the subsequent 16 h. So for this patient: • volume = 4 ml x 60 kg x 20% = 4800 ml. • Half volume in first 8 h = 2400 ml (subsequent 2400 ml over 16 h). 1000 ml This would not represent sufficient fluid replacement in the first 8 h. 1200 ml Again, this would not represent sufficient fluid replacement within