Multiple Choice Questions

Transcription

1 The rationale and the strategies to achieve perioperative glycaemic control 1. Diabetes is a group of metabolic conditions characterized by hyperglycaemia. The following statements about diabetes and surgical outcome are true: (a). Hyperglycaemia is associated with increased morbidity and mortality and length of stay from all causes, excluding cerebrovascular events. (b). Increased rates of harm and death are only seen in cohorts of patients if the target blood glucose concentration is <4 mmol litre 1. (c). With modern surveillance techniques, the incidence of undiagnosed diabetes is negligible. (d). Undiagnosed diabetes in the surgical patient is a benign condition. (e). In a patient on variable-rate intravenous insulin infusion (VRIII) having a repair of an aortic abdominal aneurysm, a high blood glucose result invariably implies that the rate of insulin needs to be increased 2. The traditional method of managing the patient with diabetes having surgery is with variable-rate intravenous insulin infusion (VRIII). The following statements about the use of VRIII are true: (a). It is safe to discontinue VRIII in a patient with type 1 diabetes mellitus (T1DM) during an elective diagnostic laparoscopy, who had omitted all subcutaneous insulin. (b). When stopping VRIII, the correct order of events is: stop VRIII; give subcutaneous insulin; measure blood glucose. (c). A 45-year-old patient with T1DM is undergoing an emergency laparotomy for small bowel obstruction. A VRIII is running and the intraoperative blood sugar is recorded as 4.1 mmol litre 1. The previous level was 5.9 mmol litre 1. This level is safe and does not require treatment. (d). It is safe to continue using a patient s longacting insulin alongside VRIII. (e). The preferred fluid to be administered alongside VRIII is 4% dextrose in 0.18% saline 3. It is now appreciated that diabetes can be managed in the surgical patient without the use of variable-rate intravenous insulin infusion (VRIII). The following statements about the use of preoperative insulin management in surgical patients with diabetes are true: (a). A 24-year-old single mother has wellcontrolled T1DM, and is usually managed with a continuous subcutaneous insulin infusion (CSII) with a usual basal rate of 0.3 units h 1 and boluses of 1 unit for every 10 g of carbohydrate. The anaesthetic registrar is asked to review her as she requires an evacuation of retained products of conception (ERPC) the next morning. She can be managed as a day patient. Appropriate advice for the preoperative management of her diabetes is to allow her to maintain her background insulin infusion, but the rate may need to be decreased by up to 20%; check the capillary blood glucose hourly; and do not give any bolus doses until she is eating and drinking. (b). A 35-year-old male with well-controlled T1DM requires an arthroscopy on an afternoon list. His usual medication is 6 units of NovoRapid (very rapid-acting insulin analogue) with breakfast, 8 units with his lunch and 14 units with his evening meal, in addition to 12 units twice daily of background Lantus insulin. management of his diabetes is to omit his usual morning and lunchtime doses of insulin, and then resume normal medication once he is eating and drinking. (c). A 55-year-old woman with well-controlled T1DM requires a hysterectomy. It is predicted that she will not be eating normally for 18 h. Her usual diabetes medication is twice daily (NovoMix ) premixed insulin, 28 units in the morning and 14 units in the evening. 1 BJA Education Volume 17 Number Published by Oxford University Press on behalf of the British Journal of Anaesthesia 2017

2 management of her diabetes is to use VRIII until she is eating and drinking normally. (d). When insulins are prescribed it is essential to use the generic name of the insulin and write the word units in full. (e). A 65-year-old obese male with well-controlled T2DM and normal renal function is managed with metformin 1 g at night, liraglutide 1.2 mg once daily and gliclazide 160 mg twice daily. He requires a total hip replacement. management of his diabetes is to continue the metformin and liraglutide unchanged, and omit the morning dose of gliclazide. 4. It is now appreciated that diabetes can be managed in the surgical patient without the use of variable-rate intravenous insulin infusion (VRIII). The following statements about the perioperative management of patients with type 2 diabetes are true: (a). A 65-year-old male with diet-controlled type 2 diabetes mellitus (T2DM) and an HbA1c of 53 mmol mol 1 (7%) requires an arthroscopy. An appropriate strategy to manage his diabetes perioperatively would be to commence him on metformin to get his HbA1c lower than 48 mmol mol 1 (6.5%). (b). A 75-year-old male with well-controlled T2DM and an HbA1c of 53 mmol mol 1 (7%) requires a total hip replacement. His usual medication is metformin twice daily and canagliflozin once daily. An appropriate strategy to manage his diabetes perioperatively would be to continue his metformin unchanged and stop his canagliflozin. (c). A 73-year-old male with well-controlled T2DM and an HbA1c of 48 mmol mol 1 (6.5%) requires an open anterior resection for a rectal tumour. His usual medication is metformin and gliclazide. An appropriate strategy to manage his diabetes perioperatively would be to continue both of these medicines during the perioperative period. (d). A 45-year-old woman with well controlled T2DM and an HbA1c of 53 mmol mol 1 (7%) requires sinus surgery. She is scheduled for an afternoon operating list. Her usual medication is metformin three times daily, gliclazide twice daily and linagliptin once daily. An appropriate strategy to manage her diabetes perioperatively would be to give the morning and evening doses of metformin but omit the lunchtime dose, omit the morning dose of gliclazide and give the linagliptin as normal. (e). An 80-year-old partially sighted male with poorly controlled diabetes [HbA1c of 81 mmol mol 1 (9.5%)] gets recurrent clot retentions as a result of his bladder cancer. The surgeons want to perform a transurethral resection of the bladder tumour. He is currently managed with metformin and glipizide for his diabetes. He should be told to go back to his general practitioner (GP) so that the GP can optimize his diabetes, and he should only be invited back to the preoperative assessment clinic once the HbA1c is <69 mmol mol 1 (<8.5%) Safe obstetric anaesthesia in low- and middle-income countries 1. A 32-year-old gravida 3 parity 2 woman has a hypovolaemic cardiac arrest in a local health centre in rural Burundi after uterine rupture during spontaneous labour at home. The following are examples of the first delay to care in the three delays framework: (a). The woman s abdominal pain was misinterpreted as normal labour pain when she was assessed at the health centre. (b). The woman and her family were not aware of the risk associated with labour after a previous classical Caesarean delivery. (c). The nearest health-care facility was a 3-h walk from the family s home. (d). The woman s husband had to borrow money to pay for her visit to the health centre and surgery, after using the family s savings to pay for her first Caesarean delivery. (e). There was no blood available for transfusion when the woman started to display signs of hypovolemic shock. 2. A 25-year-old primigravida living in Sierra Leone, one of the countries with the highest recorded maternal mortality ratio (MMR) worldwide, is in her third trimester of pregnancy and approaching term. Which of the following are more likely to be causes of mortality for this patient in her home 2 BJA Education Volume 17 Number

3 country than for a similar patient living in a highincome country (HIC)? (a). Haemorrhagic shock secondary to retained placenta. (b). Severe rheumatic mitral stenosis leading to pulmonary oedema and respiratory failure during labour. (c). Unrecognized oesophageal intubation during the induction of general anaesthesia for Caesarean delivery. (d). Disseminated tuberculosis with underlying human immunodeficiency virus (HIV) infection. (e). Local anaesthetic systemic toxicity after a regional anaesthetic procedure. 3. Benefits of intravenous ketamine general anaesthesia for Caesarean delivery include: (a). Protection from pulmonary aspiration of gastric contents. (b). Maintenance of ventilatory reflexes. (c). Greater hemodynamic stability than other induction agents. (d). Concurrent analgesic properties. (e). Maintenance of airway-protective reflexes. 4. A 23-year-old gravida 2 parity 1 patient requires a forceps-assisted delivery for obstructed labour in Mali. Complications of intrathecal injection that are more likely to result from single-shot low-dose spinal analgesia when compared with standard spinal anaesthesia include: (a). Hypotension requiring fluid resuscitation. (b). Postdural puncture headache. (c). Motor block limiting ambulation. (d). Total high spinal anaesthesia. (e). Fetal bradycardia requiring fetal resuscitation Diabetes medication pharmacology 1. Diabetes is a group of metabolic conditions characterized by hyperglycaemia. The following statements about diabetes are true: (a). The terms non-insulin dependent diabetes (NIDDM), maturity onset diabetes and type 2 diabetes mellitus (T2DM) are synonymous. (b). Gestational diabetes is a benign syndrome. (c). The incidence of diabetes has remained static and the incidence of diabetes in the surgical population is the same as in the general population. (d). Type 1 diabetes mellitus (T1DM) is caused by a single genetic mutation. (e). Treatment for T2DM is by diet alone; by oral hypoglycaemic agents and diet; or by oral hypoglycaemic agents, diet and insulin. 2. Insulin is a naturally occurring peptide that is released from the β cells in the pancreas. The following statements about insulin are true: (a). There is homogeneity across species, and animal and human insulins are identical. (b). The treatment of diabetes was revolutionized in the 1930s, when human insulin became available. (c). Analogue insulins differ from human insulin because of minor molecular changes and have altered pharmacokinetics as a result of altered drug metabolism. (d). Insulin can be classified according to the following criteria: the speed of onset and length of action after subcutaneous injection; the type of insulin, i.e. bovine, porcine or based on human insulin using recombinant DNA technology; whether the preparation contains only one type of insulin or two types. (e). It is safe to take down a variable-rate intravenous insulin infusion (VRIII) in the anaesthetic room before induction of surgery in a patient with type 1 diabetes mellitus (T1DM). 3. Insulin is used to treat diabetes. The following statements about the different insulin preparations and regimes are true: (a). The very rapid-acting insulin analogues have an onset of action within min and peak of action within an hour, and their action lasts for up to 4 h. These pharmacokinetics make them ideally suited to be used to treat inpatient hyperglycaemia. (b). Soluble insulins such as Actrapid are the preferred insulin forms to be used on the surgical ward in variable-rate intravenous 3 BJA Education Volume 17 Number

4 insulin infusion (VRIII), and to treat transient hyperglycaemia. (c). The biphasic mixed insulins contain a mixture of short-acting insulins and an intermediateacting insulin. NovoMix 30 is a mixture of 70% insulin aspart (rapid-acting analogue insulin) and 30% insulin aspart protamine (intermediate-acting), whilst Humulin M3 is a mixture of 70% isophane insulin and 30% soluble insulin. (d). Actrapid can be safely used to provide subcutaneous basal background insulin to inpatients with type 1 diabetes. (e). Continuous subcutaneous insulin infusion (CSII) pump therapy allows patients with type 1 diabetes to maintain better glycaemic control compared with multiple dose insulin (MDI), and patients prefer CSII as they only need to perform three blood glucose measurements per day. 4. Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance. The following statements are true about the pharmacological treatment of T2DM: (a). Metformin is a biguanide, and is effective in reducing glycated haemoglobin (HbA1c) in patients with T2DM. The risk of hypoglycaemia is low, but because of the risk of lactic acidosis and acute kidney injury (AKI) the summary of product characteristics states that it must be stopped 48 h before surgery. (b). T2DM can be treated pharmacologically with oral hypoglycaemic agents, and there are currently eight classes of these agents. (c). All non-insulin glucose-lowering medications actively lower the capillary blood glucose concentration, and hypoglycaemia is an intrinsic risk in the starved state. (d). The use of glucagon-like peptide-1 (GLP-1) analogues or dipeptidyl peptidase-4 (DPP-4) inhibitors does not increase the risk of pulmonary aspiration of gastric contents when a supraglottic airway is used. (e). As the risk of hypoglycaemia with sodium glucose transporter 2 inhibitors is low, these agents can be safely continued in the perioperative period Hypoxic pulmonary vasoconstriction 1. The following are recognized causes of chronic pulmonary artery hypertension: (a). Left-sided heart disease. (b). Altitude sickness. (c). Obstructive sleep apnoea (OSA). (d). Pulmonary embolism. (e). Long-term sildenafil use for erectile dysfunction. 2. Concerning hypoxic pulmonary vasoconstriction (HPV): (a). The process occurs in three distinct phases. (b). It is magnified by the use nitric oxide and prostacyclin. (c). It is mediated by pulmonary artery smooth muscle cells. (d). It is enhanced by acidaemia. (e). It is enhanced by iron deficiency. 3. Regarding hypoxic pulmonary vasoconstriction (HPV) and general anaesthesia: (a). Nitrous oxide has little effect on HPV. (b). Propofol has little effect on HPV. (c). Sevoflurane has little effect on HPV at clinically used doses. (d). Volatile agents attenuate the effects of HPV above 1 minimum alveolar concentration (MAC). (e). The HPV response is a key factor in maintaining oxygenation in healthy patients undergoing two-lung general anaesthesia. 4. The following drugs reduce the magnitude of hypoxic pulmonary vasoconstriction (HPV): (a). Bosentan. (b). Remifentanil (c). Acetazolamide. (d). Norepinephrine. (e). Dopamine. 4 BJA Education Volume 17 Number

5 The spleen 1. Concerning the physiology and anatomy of the spleen: (a). The spleen is a primary lymphoid organ. (b). Five hundred millilitres of blood can be stored in the spleen and mobilized at any time. (c). The splenic artery is a branch of the coeliac axis. (d). The pancreas may reach the splenic hilum. (e). The stomach is posterior to the spleen. 2. Concerning splenic artery aneurysms: (a). They are the third most common abdominal aneurysms. (b). They are more common in pregnancy. (c). In a haemodynamically unstable patient with a ruptured splenic artery aneurysm, endovascular ablation should be considered. (d). The overall mortality rate of ruptured splenic artery aneurysm in otherwise well pregnant women is as high as 75%. (e). A splenic artery aneurysm greater than 1.5 cm in diameter should be immediately treated by endovascular ablation. 4. Concerning iatrogenic splenic injury and trauma: (a). In the haemodynamically stable trauma patient, irrespective of the grade of injury, patient age or the presence of associated injuries, a trial of non-operative management should be considered. (b). Because of better visualization of surrounding structures, open colorectal surgery is less likely to cause splenic injury compared with laparoscopic colorectal procedures. (c). With regard to splenic injury grading, a subcapsular haematoma greater than 50% of the surface area classes this injury as moderate. (d). In the haemodynamically unstable trauma patient, computed tomography (CT) scans are a vital diagnostic work-up tool aiding decisionmaking as to whether to proceed to emergency laparotomy or observe. (e). Long-term antibiotics are recommended after splenic angioembolization for splenic trauma. 3. Concerning splenectomy: (a). Before splenectomy for idiopathic thrombocytopenia purpura (ITP), a platelet transfusion should be administered to bring the platelet count to above 50 (normal range ) 109 litre 1. (b). In the lateral decubitus position a ventilation/perfusion (V/Q) mismatch may occur, with ventilation greatest in the dependent lung. (c). During splenectomy there is potential for massive blood loss. (d). In patients with spherocytosis the patient should be allowed to passively cool to C to reduce the likelihood of crises. (e). In a patient with overwhelming postsplenectomy infection (OPSI) syndrome, blood cultures can show a number of bacterial colonies up to times higher than the colony count in common septicaemia. 5 BJA Education Volume 17 Number