Post-induction hypotension in a patient on an SGLT2 inhibitor
A 64-year-old woman with type 2 diabetes (HbA1c 8.1%, eGFR 52 mL/min/1.73 m²) is scheduled for open cholecystectomy. Her medications include empagliflozin, metformin, ramipril, and atorvastatin. She has fasted since midnight; the case starts at 08:00. After propofol 2 mg/kg, fentanyl 100 mcg, and rocuronium 50 mg, her blood pressure falls from 142/84 to 78/44 mmHg, heart rate 92 bpm, and remains low after 200 mL of crystalloid and two 50 mcg phenylephrine boluses. Capillary glucose is 9.8 mmol/L. The surgeon is ready to incise.
1. List the plausible contributors to this hypotension and explain how you would discriminate between them at the bedside.
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Contributors to consider:
- Anesthetic-induced vasodilation and myocardial depression - propofol blunts sympathetic tone; the response to phenylephrine suggests some vasoplegia but persistence argues for more.
- Relative/absolute hypovolemia - prolonged fasting plus bowel prep; a 200 mL bolus is small. Assess with passive leg raise or a mini fluid challenge with stroke-volume or pulse-pressure-variation trending rather than a single number.
- ACE inhibitor effect - ramipril taken the morning of surgery blunts the angiotensin II response to sympathectomy; refractory hypotension after induction is classic. This is a strong candidate given the poor response to pressor.
- Sepsis - cholangitis/cholecystitis can present deceptively; check temperature trend, white cell count, lactate, and whether the patient looks unwell.
- Anaphylaxis - less likely without rash, bronchospasm, or rapid onset, but keep on the differential.
Bedside discrimination: trend blood pressure with each intervention, use dynamic preload indices, check lactate, and examine for rash/wheeze. A sustained response to a small fluid bolus favors hypovolemia; a sustained response to norepinephrine favors vasoplegia.
2. What is the specific concern about empagliflozin in this perioperative context, and how does it change your management?
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SGLT2 inhibitors cause glycosuria, osmotic diuresis, and mild volume depletion, and carry a recognized risk of euglycemic diabetic ketoacidosis (eDKA) perioperatively - glucose can be near-normal while ketones and acidosis are significant. Fasting, surgical stress, and reduced carbohydrate intake are triggers.
Management implications:
- Hold empagliflozin for at least 3 days before elective surgery (per labeling) - this case did not, so treat as at-risk.
- Check a blood ketone (beta-hydroxybutyrate) and a venous blood gas if there is unexplained tachycardia, hypotension, or nausea; do not rely on glucose.
- If eDKA is present, treat with IV insulin plus dextrose-containing fluid and aggressive resuscitation; do not simply give more fluid and pressors.
- Continue metformin unless contraindicated; monitor renal function.
- Document the medication error for the preoperative assessment pathway.
3. Outline your immediate next 10 minutes if the blood pressure remains 80/45 after another 250 mL of fluid.
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- Reassess depth of anesthesia - reduce propofol/volatile to the minimum needed; confirm adequate analgesia.
- Escalate vasopressor - start a norepinephrine infusion (or push-dose) titrated to MAP ≥65 mmHg; phenylephrine alone may be insufficient if there is myocardial depression.
- Rule out the dangerous causes - check blood ketones and lactate, send for a venous gas, examine for rash/wheeze, and consider an arterial line for reliable pressure and sampling.
- Consider a transient ACE-inhibitor effect - vasoplegia may require higher norepinephrine doses; vasopressin can be added if refractory.
- Decide about proceeding - if the patient is unstable or eDKA is confirmed, delay incision, treat, and discuss with the surgeon; do not induce further surgical stress on an un-resuscitated patient.
- Document and debrief - record the medication issue and communicate to the ward team.