Answer: Malignant hyperthermia

Malignant hyperthermia (MH) is a life-threatening clinical syndrome of hypermetabolism involving the skeletal muscle. It is triggered in susceptible individuals primarily by the volatile inhalational anaesthetic agents and the muscle relaxant succinylcholine, though other drugs have also been implicated as potential triggers. MH is not an allergy but an inherited disorder that is found both in humans and in swine.

In persons susceptible to MH, the ryanodine receptor in skeletal muscle is abnormal, and this abnormality interferes with regulation of calcium in the muscle. An abnormal ryanodine receptor that controls calcium release causes a build-up of calcium in skeletal muscle, resulting in a massive metabolic reaction.

This hypermetabolism causes increased carbon dioxide production, metabolic and respiratory acidosis, accelerated oxygen consumption, heat production, activation of the sympathetic nervous system, hyperkalaemia, disseminated intravascular coagulation (DIC), and multiple organ dysfunction and failure. Early clinical signs of MH include an increase in end-tidal carbon dioxide (even with increasing minute ventilation), tachycardia, muscle rigidity, tachypnoea, and hyperkalaemia. Later signs include fever, myoglobinuria, and multiple organ failure.

A massive blood transfusion is defined as the replacement of a patient’s total blood volume in <24 h
The abnormalities which result include effects upon coagulation status, serum biochemistry, acid-base balance and temperature homeostasis.
One of the complications is Transfusion-related acute lung injury
(TRALI) which is the most common cause of major morbidity and death after transfusion. It presents as an acute respiratory distress syndrome (ARDS) either during or within 6 h of transfusion.

Clinical features
Hypoxaemia, dyspnoea, cyanosis, fever, tachycardia and hypotension result from non-cardiogenic pulmonary oedema. The radiographic appearance is of bilateral pulmonary infiltration, characteristic of pulmonary oedema. It is important to differentiate TRALI from other causes of ARDS such as circulatory overload or myocardial or valvular heart disease. Invasive monitoring in TRALI demonstrates normal intracardiac pressures

Pathogenesis
Two different mechanisms for the pathogenesis of TRALI have been identified: immune (antibody-mediated) and non-immune. Immune TRALI results from the presence of leucocyte antibodies in the plasma of donor blood directed against human leucocyte antigens (HLA) and human neutrophil alloantigens (HNA) in the recipient. Antibodies present in the recipient only rarely cause TRALI. In up to 40% of patients, leucocyte antibodies cannot be detected in either donor or recipient. In these cases, it is possible that reactive lipid products released from the membranes of the donor blood cells act as the trigger. This is known as non-immune TRALI.
The target cell in both forms of TRALI is the neutrophil granulocyte. On activation of their acute phase cycle, these cells migrate to the lungs where they become trapped within the pulmonary microvasculature. Oxygen-free radicals and other proteolytic enzymes are then released which destroy the endothelial cells of the lung capillaries. A pulmonary capillary leak syndrome develops with the exudation of fluid and protein into the alveoli resulting in pulmonary oedema. The majority of reactions are severe, and often life-threatening; 70% require mechanical ventilation and 6–9% are fatal. A definitive diagnosis requires antibody detection. The mortality in non-immune TRALI is lower, and the syndrome is encountered predominantly in critically ill patients.
Other Complications of blood transfusion
Early:
– Haemolytic reactions
Immediate
Delayed
– Non-haemolytic febrile reactions
– Allergic reactions to proteins, IgA
– Reactions secondary to bacterial contamination
– Circulatory overload
– Air embolism
– Thrombophlebitis
– Hyperkalaemia
– Citrate toxicity
– Hypothermia
– Clotting abnormalities (after massive transfusion)
Late:
– Transmission of infection
– Viral (hepatitis A, B, C, HIV, CMV)
– Bacterial (Treponeum pallidum, Salmonella)
– Parasites (malaria, toxoplasma)
– Graft-vs-host disease
– Iron overload (after chronic transfusions)
– Immune sensitization (Rhesus D antigen)

Acute transfusion reactions present as adverse signs or symptoms during or within 24 hours of a blood transfusion. The most frequent reactions are fever, chills, pruritus, or urticaria, which typically resolve promptly without specific treatment or complications.

Answer: Serum phosphate

Refeeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally. These shifts result from hormonal and metabolic changes and may cause serious clinical complications. The hallmark biochemical feature of refeeding syndrome is hypophosphatemia. However, the syndrome is complex and may also feature abnormal sodium and fluid balance; changes in glucose, protein, and fat metabolism; thiamine deficiency; hypokalaemia; and hypomagnesaemia.
During refeeding, glycaemia leads to increased insulin and decreased secretion of glucagon. Insulin stimulates glycogen, fat, and protein synthesis. This process requires minerals such as phosphate and magnesium and cofactors such as thiamine. Insulin stimulates the absorption of potassium into the cells through the sodium-potassium ATPase symporter, which also transports glucose into the cells. Magnesium and phosphate are also taken up into the cells. Water follows by osmosis. These processes result in a decrease in the serum levels of phosphate, potassium, and magnesium, all of which are already depleted. The clinical features of the refeeding syndrome occur as a result of the functional deficits of these electrolytes and the rapid change in basal metabolic rate.

Symptoms of hypophosphatemia include:

confusion or hesitation
seizures
muscle breakdown
neuromuscular problems
acute heart failure

Deficiency in thiamine can lead to Korsakoff’s syndrome (retrograde and anterograde amnesia, confabulation) and Wernicke’s encephalopathy (ocular abnormalities, ataxia, confusional state, hypothermia, coma). These symptoms are not present in the patient so Thiamine deficiency can be ruled out and there is no need to do tests for Serum vitamin B.

Airway obstruction: In the first 24 hours it is most likely from a compressive hematoma. After 24 hours consider laryngeal dysfunction secondary to hypocalcaemia.
In this patient, the most likely cause is a haematoma.
Definitive therapy is opening the surgical incision to evacuate the hematoma. Re-intubation may be lifesaving for persistent airway obstruction. Consider awake fibreoptic intubation.

Bowel preparation is a significant aspect of the flexible sigmoidoscopy procedure. Clear visibility of the bowel mucosa is critical for a thorough examination. The combination of a light breakfast in the morning and the application of 1 or 2 phosphate enemas a few hours before the examination is a safe and commonly used method of preparing a patient for a flexible sigmoidoscopy procedure.

The immediate treatment of hypercalcaemia involves intravenous fluid resuscitation. This may be complemented with the use of bisphosphonates and sometimes, diuretics. However, fluids are administered first. Normal saline is usually preferred for this over other solutions.

Urgent management in hypercalcaemia is indicated if:
1. Serum calcium level >3.5 mmol/L
2. Reduced consciousness
3. Severe abdominal pain
4. Pre-renal failure

Management options include:
1. Intravenous fluid resuscitation with 3–6 litres of 0.9% normal saline in 24 hours
2. Concurrent administration of calcitonin to help lower calcium levels
3. Medical therapy (usually if corrected calcium >3.0mmol/L)

Gaining venous access in small children is challenging most of the times especially in cases of trauma. Therefore, intraosseous infusions should be preferred in this setting. Broviac lines are long-term IV access systems with narrow lumens and, hence, would be unsuitable.

Intraosseous access is typically undertaken at the anteromedial aspect of the proximal tibia and provides access to the marrow cavity and circulatory system. Although traditionally preferred in paediatric practice, it may be used in adults as well, and a wide range of fluids can be infused using this approach.

Open haemorrhoidectomy is traditionally viewed as a painful procedure. Most operations are performed under general or regional anaesthesia. Following excisional haemorrhoidectomy, severe pain is not unusual, a well placed caudal anaesthetic will counter this. A pudendal nerve block is an alternative but is less effective than a caudal.

Atrial fibrillation occurring after a colonic resection most likely represents an anastomotic leak. The best modality to visualize this would be an abdominal CT scan. Any bowel anastomosis can leak, sometimes as a result of technical failings and at other times, its patient factors such as background disease that contribute. As a general rule, rectal resections carry the highest risk of anastomotic leak. Indeed, low anterior resections are routinely defunctioned with loop ileostomy to mitigate the clinically effects of a leak. Left sided colonic resections carry a higher risk of anastomotic leak than right sided resections. The reason for this is that an ileocolic anastomosis (or indeed any small bowel anastomosis) has a very low risk of leak (provided the small bowel is otherwise healthy). Where a leak is suspected (new AF and raised inflammatory markers 5 days post resection), the correct course of action is to arrange cross sectional imaging with a CT scan. If a leak is confirmed and the patient is septic, then they should go back to theatre, the anastomosis taken down and the bowel ends exteriorized.

An acute dystonic reaction is characterized by involuntary contractions of muscles of the extremities, face, neck, abdomen, pelvis, or larynx in either sustained or intermittent patterns that lead to abnormal movements or postures. The symptoms may be reversible or irreversible and can occur after taking any dopamine receptor-blocking agents.
The aetiology of acute dystonic reaction is thought to be due to a dopaminergic-cholinergic imbalance in the basal ganglia. Reactions usually occur shortly after initiation of an offending agent or an increased dose of a possible offending agent.
Anticholinergic agents and benzodiazepines, procyclidine are the most commonly used agents to reverse or reduce symptoms in acute dystonic reaction. Acute dystonic reactions are often transient but can cause significant distress to the patient. Although rare, laryngeal dystonia can cause life-threatening airway obstruction.

If patients need IV fluids for routine maintenance alone, restrict the initial prescription to:
25–30 ml/kg/day of water and
approximately 1 mmol/kg/day of potassium, sodium and chloride and
approximately 50–100 g/day of glucose to limit starvation ketosis.
Weight-based potassium prescriptions should be rounded to the nearest common fluids available (for example, a 67 kg person should have fluids containing 20 mmol and 40 mmol of potassium in 24 hours). Potassium should not be added to intravenous fluid bags as this is dangerous.

Sodium chloride 0.9%, with or without additional potassium, is one of the most commonly used IV fluids in UK practice.

Glucose 5% solution provides a useful means of giving free water for, once the glucose is metabolised, the fluid is distributed throughout total body water. It is, therefore, a potentially useful means of correcting or preventing simple dehydration and the glucose content will also help to prevent starvation ketosis, although it is important to recognize that it will not make much of a contribution to covering patients overall nutritional needs. The use of 5% glucose, will increase risks of significant hyponatraemia, particularly in children, the elderly, patients on diuretics and those with excess ADH due to osmotic and non-osmotic stimuli (a problem is seen quite frequently in hospitalized patients). Nevertheless, hyponatremia is likely to be avoided by not exceeding recommended volumes of maintenance IV fluids and by careful monitoring of patients’ clinical volume status and electrolyte measurements.

Desmopressin is useful in managing mild to moderate episodes of bleeding in von Willebrand disease (vWD).

vWD is the most common hereditary coagulopathy resulting from the deficiency or abnormal function of von Willebrand factor (vWF). vWF promotes platelet adhesion to damaged endothelium and other platelets and is also involved in the transport and stabilization of factor VIII.

There are seven subtypes of vWD. Type 1 vWD (autosomal dominant) is the most common and accounts for 80% of the cases. Type 2 vWD (autosomal dominant or recessive) accounts for 15% of the cases. There is a significant spectrum of severity ranging from spontaneous bleeding and epistaxis through to troublesome excessive bleeding following minor procedures.

Bleeding time is mostly used as a diagnostic test for vWD. Treatment options include administration of tranexamic acid for minor cases undergoing minor procedures. More significant bleeding or procedures respond well to desmopressin (DDAVP). It is most effective in type 1 vWD, less effective in type 2 and contraindicated in type 2B. Individuals who cannot have desmopressin or in whom it is contraindicated usually receive factor VIII concentrates containing vWF.

Chyle leakage is one of the most challenging complications following an esophagectomy and can lead to hypovolemia, metabolic and nutritional depletion, infection, and even death. The leakage occurs in 1.1 to 3.7% of esophagectomy patients; mortality occurs in excess of 50% of patients. Surgeons administer a lipid rich material prior to surgery to facilitate its identification if it occurs.

Dextran 40 and 70 have a higher rate of causing anaphylaxis than either gelatins or starches.

Dextrans are branched polysaccharide molecules, with dextran 40 and 70 available. The high-molecular-weight dextran 70 may persist for up to eight hours. They inhibit platelet aggregation and leucocyte plugging in the microcirculation, thereby, improving flow through the microcirculation. They are primarily used in sepsis.
Unlike many other intravenous fluids, dextrans are a recognised cause of anaphylaxis.

Acute respiratory distress syndrome (ARDS) is an inflammatory process in the lungs that induces non-hydrostatic protein-rich pulmonary oedema. The immediate consequences are profound hypoxemia, decreased lung compliance, and increased intrapulmonary shunt and dead space. The clinicopathological aspects include severe inflammatory injury to the alveolar-capillary barrier, surfactant depletion, and loss of aerated lung tissue.

The most recent definition of ARDS, the Berlin definition, was proposed by a working group under the aegis of the European Society of Intensive Care Medicine. It defines ARDS by the presence within 7 days of a known clinical insult or new or worsening respiratory symptoms of a combination of acute hypoxemia (PaO2/FiO2 ≤ 300 mmHg), in a ventilated patient with a positive end-expiratory pressure (PEEP) of at least 5 cmH2O, and bilateral opacities not fully explained by heart failure or volume overload i.e. the heart pressure is norma. The Berlin definition uses the PaO2/FiO2 ratio to distinguish mild ARDS (200 < PaO2/FiO2 ≤ 300 mmHg), moderate ARDS (100 < PaO2/FiO2 ≤ 200 mmHg), and severe ARDS (PaO2/FiO2 ≤ 100 mmHg).
Most cases of ARDS in adults are associated with pulmonary sepsis (46 percent) or nonpulmonary sepsis (33 percent). Risk factors include those causing direct lung injury (e.g., pneumonia, inhalation injury, pulmonary contusion) and those causing indirect lung injury (e.g., nonpulmonary sepsis, burns, transfusion-related acute lung injury)

Most patients with ARDS need sedation, intubation, and ventilation while the underlying injury is treated. Any ventilator mode may be used, according to the Surviving Sepsis Clinical Practice Guideline and the National Heart, Lung, and Blood Institute’s ARDS Network (ARDSNet). Respiratory rate, expiratory time, positive end-expiratory pressure, and FiO2 are set following ARDSNet protocols. Settings are adjusted to maintain an oxygen saturation of 88 to 95 percent and a plateau pressure of 30 cm H2O or less to avoid barotrauma. Clinical practice guidelines recommend maintaining an arterial pH of 7.30 to 7.45, although patients in some research trials have tolerated permissive hypercapnia and a pH as low as 7.15

Answer: Allow the wound to heal by secondary intention

A perianal abscess is a type of anorectal abscess that is confined to the perianal space. Other causes can include inflammatory bowel diseases such as Crohn’s disease, as well as trauma, or cancerous origins. Patients with recurrent or complex abscesses should be evaluated for Crohn’s disease. Perianal abscesses are the most common type of anorectal abscesses. These abscesses can cause significant discomfort for patients. They are located at the anal verge and if left untreated can extend into the ischioanal space or intersphincteric space since these areas are continuous with the perianal space. They can also cause systemic infection if left untreated. Patients will complain of anal pain which may be dull, sharp, aching, or throbbing. This may be accompanied by fever, chills, constipation, or diarrhoea. Patients with perianal abscess typically present with pain around the anus, which may or may not be associated with bowel movements, but is usually constant. Purulent discharge may be reported if the abscess is spontaneously draining, and blood per rectum may be reported in a spontaneously draining abscess.

A physical exam can typically rule out other causes of anal pain, such as haemorrhoids, and will yield an area of fluctuance or an area of erythema and induration in the skin around the perianal area. Cellulitis should be noted and marked if extending beyond the fluctuant area.

Perianal abscesses are an indication for timely incision and drainage. Antibiotic administration alone is inadequate and inappropriate. Once incision and drainage are performed, there is no need for antibiotic administration unless certain medical issues necessitate the use. Such conditions include valvular heart disease, immunocompromised patients, diabetic patients, or in the setting of sepsis. Antibiotics are also considered in these patients or cases with signs of systemic infection or significant surrounding cellulitis.

Incision and drainage are typically performed in an office setting, or immediately in the emergency department. Local anaesthesia with 1% lidocaine may be administered to the surrounding tissues. A cruciate incision is made as close to the anal verge as possible to shorten any potential fistula formation. Blunt palpation is used to ensure no other septation or abscess pocket is missed. It is useful before completion of procedure to excise a skin flap of the cruciate incision or the tips of the four skin flaps to ensure adequate drainage and prevent premature healing of the skin over the abscess pocket. Packing may be placed initially for haemostasis. Continual packing may be further utilized for healing by secondary intention. Patients are encouraged to keep the incision and drainage site clean. Sitz baths may assist in pain relief.

More extensive abscesses may require the operating room for the adequate exam under anaesthesia to ensure adequate drainage, as well as inspect for other diseases such as fistula in ano.

Vomiting usually results in hypokalaemia, and hyponatremia would least likely occur as a result of it. Hyponatremia is a common postoperative finding among patients and hence serum sodium must be carefully monitored. Addison disease, SIADH, diuretic therapy can all cause hyponatremia.

The laryngeal airway mask (LAM) is a device for anaesthetic air way management. The primary advantage of the laryngeal airway mask (LAM) over the face mask during general anaesthesia includes the ability to obtain, secure, and maintain a patent airway. The laryngeal mask airway is passed beyond the tongue, forming a seal with the laryngeal inlet and eliminating the most common cause of upper airway obstruction in the non-intubated patient.

Maintenance of a patent airway with fewer episodes of oxygen desaturation has been demonstrated for the LAM as compared with the face mask. Environmental inhalational gas exposure values associated with the use of a LAM have been shown to be less than those achieved with a face mask and comparable to those with the use of an endotracheal tube. Ocular and facial nerve injuries associated with prolonged face mask use are also avoided. The advantages of the laryngeal mask airway include anaesthetic management, induction, maintenance, and emergence.

The placement of the LMA can be accomplished without muscle relaxants and laryngoscopy. The avoidance of succinylcholine may decrease the incidence of post-operative myalgias. Significant and potentially detrimental hemodynamic changes associated with both laryngoscopy and tracheal intubation are also attenuated and are of shorter duration with the use of the laryngeal mask airway. Compared with an endotracheal tube, the anaesthetic requirement for tolerance of the LAM has also been reported to be less. Differences in the response to the LAM are also seen during emergence from anaesthesia. The LAM is well tolerated, with a lower reported incidence of hyperactive respiratory occurrences (e.g., coughing, laryngospasm, breath holding) than with an endotracheal tube. The anatomic placement of the LAM, with its lack of impingement on the trachea and vocal cords, minimizes complications that are potentially associated with intubation. According to Swann et al. incidence of postoperative sore throat as well as hoarseness is less with the LAM compared with the endotracheal tube.

It has been well established that any delay in the resumption of normal oral diet after major surgery is associated with increased rates of infectious complications and delayed recovery. Early oral diet is safe 4 h after surgery in patients with a new non-diverted colorectal anastomosis. Some report that low residue diet, rather than a clear liquid diet, after colorectal surgery is associated with less nausea, faster return of bowel function, and a shorter hospital stay without increasing postoperative morbidity when administered in association with prevention of postoperative ileus. Spontaneous food intake rarely exceeds 1200–1500 kcal/day. To reach energy and protein requirements, additional oral nutritional supplements are useful.

Answer: They should be placed first on the operating list whenever possible

Patients with diet controlled diabetes are all
suitable for day case surgery if the procedure itself
is suitable for day surgery and all other criteria are
fulfilled.
People with diabetes controlled by oral or injected
medication are suitable for day case surgery if:
• They fulfil all day case criteria
• They can be first / early on a morning or afternoon
list.
Prioritise patients with diabetes on the list. This reduces the starvation time and hence the likelihood of the patient requiring a VRIII.

Insulin should never be stopped in people with Type 1 diabetes because this will lead to ketoacidosis. If the starvation period is expected to require omission of more than one meal, a variable rate intravenous insulin infusion (VRIII) with concomitant glucose and electrolyte infusion will be required. Insulin requirements are increased by:
• Obesity
• Prolonged or major surgery
• Infection
• Glucocorticoid treatment.
When a VRIII is used, insulin and substrate should be infused continuously. If the infusion is stopped, there will be no insulin present in the circulation after 3-5 minutes leading to immediate catabolism.

Ototoxicity is a recognised adverse reaction with the aminoglycoside antibiotics.

Gentamicin belongs to a class of drugs known as aminoglycoside antibiotics. It is a broad-spectrum antibiotic that is most affective against aerobic gram-negative rods. Gentamicin acts by inhibiting bacterial protein synthesis. This creates a pool of inactive bacterial ribosomes that can no longer re-initiate and translate new proteins.

The hearing loss produced by gentamicin is known as gentamycin-induced ototoxicity. The antibiotic itself is not dangerous. It becomes toxic when it binds to iron in the blood and produces destructive chemical agents known as free radicals.

There is a substantial risk of hypoglycaemia in neonates following surgery, therefore 10% dextrose should be administered to them to avoid the complications associated with hypoglycaemia.

Postoperative hypertension, arrhythmias, and heart failure commonly occur in the first 2 days after surgery, but the risk of myocardial infarction persists for at least 5 or 6 days after surgery.
ECG should be done to exclude it.

Because of the substantial risk of thromboembolism early after valve replacement, perioperative initiation of anticoagulation is necessary, despite the increased risk for bleeding. Anticoagulation should be initiated within 24 h after the procedure with unfractionated heparin or low-molecular-weight heparin (LMWH).
Heparin is monitored by checking the activated partial thromboplastin time or anti-Xa activity.
Oral anticoagulants are monitored by INR.

Answer: Myofibroblasts

Fibroblasts are a type of cell which have mesenchymal origin and can exhibit either non-contractile or highly contractile phenotype. Under normal conditions, fibroblasts function to maintain tissue homeostasis by regulating the turnover of extracellular matrix (ECM). When tissues are injured, however, fibroblasts around the injured region differentiate into myofibroblasts, a type of highly contractile cells that produce abundant ECM proteins. While the mechanisms of wound healing are not completely understood, it has become clear that both fibroblasts and myofibroblasts play a critical role in the wound healing process. Specifically, the traction forces of fibroblasts and coordinated contraction of myofibroblasts are believed to be responsible for wound contraction and closure. However, excessive myofibroblast activity, accompanied by elevated levels of mechanical stress in the healing region, often causes scar tissue formation, and in the worst case, contracture of tissues (e.g. Dupuytren’s contracture), leading to local immobilization and loss of function.

Repair of an inguinal hernia under local anaesthesia has a short operative time, and patients are usually ambulant immediately after. Furthermore, the family history of this patient is unlikely to be significant and therefore, he is at a very low risk of developing a pulmonary embolism (PE).

Deep vein thrombosis (DVT) may develop insidiously in many surgical patients. If left untreated, it may progress to PE. The following surgical patients are at increased risk of developing DVT:

1. Surgery greater than 90 minutes at any site or greater than 60 minutes if the procedure involves lower limbs or pelvis
2. Acute admissions with inflammatory process involving the abdominal cavity
3. Expected significant reduction in mobility
4. Age over 60 years
5. Known malignancy
6. Thrombophilia
7. Previous thrombosis
8. BMI >30 kg/m2
9. Taking hormone replacement therapy or contraceptive pills
10. Varicose veins with phlebitis

Thromboprophylaxis can be mechanical or therapeutic. The former includes:
1. Early ambulation after surgery: cheap and effective
2. Compression stockings (contraindicated in peripheral arterial disease)
3. Intermittent pneumatic compression devices
4. Foot impulse devices

Therapeutic agents for thromboprophylaxis are:
1. Low-molecular-weight heparin (LMWH)
2. Unfractionated heparin
3. Dabigatran

According to the ECS Guidelines 2019, Multidetector Computed tomographic pulmonary angiography (CTPA) is the method of choice for imaging the pulmonary vasculature in patients with suspected PE. It allows adequate visualization of the pulmonary arteries down to the subsegmental level.112–114 The Prospective Investigation On Pulmonary Embolism Diagnosis (PIOPED) II study observed a sensitivity of 83% and a specificity of 96% for (mainly four-detector) CTPA in PE diagnosis.

D-dimer levels are elevated in plasma in the presence of acute thrombosis because of simultaneous activation of coagulation and fibrinolysis. The negative predictive value of D-dimer testing is high, and a normal D-dimer level renders acute PE or DVT unlikely. On the other hand, the positive predictive value of elevated D-dimer levels is low and D-dimer testing is not useful for confirmation of PE.

The patient suffers from hyperkalaemia as an adverse effect of RBCs transfusion, which causes his ECG changes.
The potassium concentration of blood increases during storage, by as much as 5–10 mmol u−1. After the transfusion, the RBC membrane Na+–K+ ATPase pumping mechanism is re-established and cellular potassium reuptake occurs rapidly. Hyperkalaemia rarely occurs during massive transfusions unless the patient is also hypothermic and acidotic.
The total extracellular potassium load, which is <0.5 mmol for fresh RBC units and only 5-7 mmol for units at expiration, rarely causes problems in the recipient because of rapid dilution, redistribution into cells, and excretion. An abnormally high potassium level (>5 mmol/l or ≥1.5 mmol/l net increase) within an hour of transfusion is classified as transfusion-associated hyperkalaemia.
Irradiation enhances potassium leakage.

Answer: Re-open the neck wound

Thyroidectomy: complications
Airway obstruction (compressing hematoma, tracheomalacia)

Incidence of hematoma is 1-2%, tracheomalacia incidence is <1%. Acute airway obstruction from hematoma may occur immediately postoperatively and is the most frequent cause of airway obstruction in the first 24 hours. Definitive therapy is opening the surgical incision to evacuate the hematoma. Re-intubation may be lifesaving for persistent airway obstruction. Consider awake fibreoptic intubation.