Collapse during an extraction in a fasting diabetic patient on a sulfonylurea
A 63-year-old man attends at 09:30 for extraction of tooth 26. His history includes hypertension on amlodipine 10 mg, type 2 diabetes treated with metformin 1 g twice daily and gliclazide 80 mg twice daily, and hyperlipidaemia on atorvastatin. He ate nothing after 20:00 the previous evening because he had been told to fast for a blood test that morning, and he took his usual diabetes medication. He had 2% lidocaine with 1:100,000 epinephrine (two cartridges) and is 10 minutes into an atraumatic extraction when he becomes pale and clammy, feels nauseated and dizzy, and says he 'needs to get up'. He is conscious but anxious. Heart rate is 52 beats per minute, blood pressure 92/58 mmHg, respiratory rate 22, SpO2 97% on room air, and he is not wheezing. There is no urticaria and no angioedema.
1. Give your differential diagnosis, name the most likely cause, and state your immediate actions in the correct order.
Read the worked answer
The differential for sudden collapse in the dental chair includes vasovagal syncope, hypoglycaemia, local anaesthetic toxicity, anaphylaxis, and an acute cardiac event such as angina or myocardial infarction. Anaphylaxis is unlikely here: it would produce urticaria, angioedema, wheeze or stridor, tachycardia and hypotension without pallor and bradycardia. Local anaesthetic toxicity typically causes circumoral numbness, tinnitus, agitation, tachycardia and hypertension followed by seizures and depression, and 3.6 mL of 2% lidocaine is far below the toxic threshold for a healthy adult. Cardiac ischaemia must stay on the list but is not the leading explanation.
The combination of pallor, diaphoresis, nausea, bradycardia and hypotension in a seated, anxious patient immediately after injection is classic vasovagal syncope. Immediate actions: stop the procedure and remove instruments from the mouth; recline the chair fully supine with the legs elevated (or Trendelenburg) to restore venous return; loosen tight clothing; give 100% oxygen by mask; monitor pulse, blood pressure and consciousness every few minutes; and do not sit him up quickly. The extraction is abandoned for the day. A capillary glucose check should be done immediately as part of the assessment - in a fasting diabetic on a sulfonylurea, hypoglycaemia is the diagnosis that must not be missed.
2. Five minutes later he has not recovered; he is confused and drowsy, and the glucometer reads 2.9 mmol/L. How do you manage this, and how does the management change if he becomes unresponsive?
Read the worked answer
A glucose of 2.9 mmol/L with confusion confirms hypoglycaemia. Because he is still able to swallow safely at this point, give 15–20 g of fast-acting oral carbohydrate - glucose gel, glucose tablets, or 150–200 mL of fruit juice or a sugary drink - then reassess after 15 minutes and repeat if still below 4 mmol/L. Once he is above 4 mmol/L and alert, give a longer-acting carbohydrate (bread, biscuits, a sandwich) to prevent recurrence, and do not let him leave unaccompanied. Do not give anything by mouth if he is drowsy or unable to swallow, because of aspiration risk.
If he becomes unresponsive: stop oral intake, protect the airway, place him in the recovery position if breathing, continue oxygen and monitoring, and give 1 mg glucagon intramuscularly (or subcutaneously) - this is the option available in a dental office without intravenous access. If a clinician competent in intravenous access is present, 20–50 mL of 50% dextrose or an equivalent dextrose infusion is faster. Call emergency services if he does not respond within 10–15 minutes, if glucagon is unavailable, or if there is any doubt about the airway. He should not be sent home alone, and his physician must be told, because a sulfonylurea plus a missed meal is a recognised cause of prolonged hypoglycaemia.
3. How would the presentation and management differ if this were anaphylaxis or a hypertensive crisis, and what should the emergency kit and the record contain?
Read the worked answer
Anaphylaxis would look different: generalised urticaria, flushing, angioedema of the lips or tongue, wheeze, stridor or a sensation of throat closure, tachycardia, and hypotension - not pallor with bradycardia. Management is immediate intramuscular epinephrine 0.5 mg of 1:1000 into the anterolateral thigh, repeated every 5 minutes as needed, with oxygen, supine positioning (sitting up if breathing is the problem), a crystalloid bolus if available, an antihistamine and corticosteroid as adjuncts only, and emergency services called. The key point is that epinephrine must not be delayed while waiting for antihistamines to work; in anaphylaxis, giving epinephrine is the difference between a good and a bad outcome, whereas in vasovagal syncope epinephrine is not indicated at all.
A hypertensive crisis would present with a throbbing headache, chest pain, breathlessness or neurological symptoms, with systolic pressure above 180 mmHg, and it requires stopping treatment, sitting the patient upright, oxygen, and urgent transfer rather than dental management.
The emergency kit should contain oxygen, an appropriate mask and bag, adrenaline 1:1000, glyceryl trinitrate spray, soluble aspirin, a salbutamol inhaler, glucagon, oral glucose, chlorphenamine and a glucose meter, with drugs checked monthly for expiry. The record must include the time of onset, vital signs serially, drugs and doses given with times, the decision to abandon treatment, the transfer or discharge decision, and the conversation with the patient and their physician.