Major Depressive Disorder (MDD)

Medication list first - The class of antidepressant, not the depression, drives the anesthetic. Get the exact agent, the dose, and how long the patient has been on it before you build a plan.

SSRIs and bleeding - SSRIs block serotonin reuptake into platelets as well as neurons, and platelet serotonin release is part of aggregation, so bleeding risk rises. The effect is additive or synergistic with NSAIDs and other antiplatelet drugs, though some studies argue it is not clinically large.

SSRIs and serotonin load - Don't stack serotonergic drugs. Meperidine, tramadol, pentazocine, metoclopramide, dextromethorphan, cyclobenzaprine, linezolid and methylene blue all raise synaptic serotonin. Clonus, hyperreflexia and dilated pupils inside a few hours of the offending dose are what you would see. See the serotonin syndrome entry.

Tricyclics and anticholinergic load - TCAs block muscarinic receptors, so expect tachycardia, dry mouth, urinary retention and a higher chance of postoperative delirium. Alpha-1 blockade adds orthostatic hypotension and histamine blockade adds sedation.

Tricyclics and cardiac conduction - Get a baseline 12-lead ECG. TCAs block fast sodium channels and prolong the QRS, and potassium channel blockade prolongs the QT with a torsades risk. QRS beyond 100 ms predicts seizures, beyond 160 ms predicts arrhythmia, and an R wave over 3 mm in aVR predicts both. Sodium bicarbonate 1 mEq/kg followed by an infusion, targeting a pH of 7.5 to 7.55, is the treatment for a widened QRS or hemodynamic instability; norepinephrine for hypotension that fluid and bicarbonate don't fix.

Tricyclics and what to avoid - Physostigmine, class 1A, 1C and class III antiarrhythmics, and flumazenil are all contraindicated in TCA toxicity. Acidosis raises the unbound fraction and worsens both cardiac and neurologic toxicity, so keep ventilation and perfusion where they belong.

MAO inhibitors and the 10-day hold - Elective general anesthesia should not proceed on a monoamine oxidase inhibitor (MAOI); the recommendation is to stop it at least 10 days beforehand, and to allow 14 days before starting a different antidepressant. That decision belongs with the prescribing psychiatrist — MAOIs are last-line agents, and a patient on one has usually failed everything else.

MAO inhibitors and vasopressor choice - Sympathomimetic amines are contraindicated on an MAOI. The same enzyme block that stops tyramine breakdown produces the tyramine pressor response, a sudden hypertensive surge that has caused fatal cerebral hemorrhage. Treat hypotension with volume and small titrated doses of a direct-acting agent rather than reaching for ephedrine.

MAO inhibitors and meperidine - Meperidine, tramadol, dextromethorphan and methadone are contraindicated on an MAOI, all through serotonin toxicity. MAOI-driven serotonin syndrome is the most severe and prolonged form, and fatalities are more likely on an MAOI than on an SSRI.

Lithium augmentation and NSAIDs - NSAIDs inhibit renal prostaglandin synthesis and significantly raise serum lithium, which has a narrow therapeutic window. Check a lithium level before adding ketorolac to a multimodal plan in a patient on lithium.

ECT and the physiologic swing - Electroconvulsive therapy (ECT) is more effective than any other treatment for severe MDD, so you will anesthetize these patients repeatedly. The stimulus drives a vagal surge first — bradycardia, a cardiac pause, sometimes asystole — and then the seizure drives a sympathetic surge with hypertension and tachycardia. A stimulus that fails to provoke a seizure can leave prolonged asystole.

ECT drugs and sequence - Methohexital about 1 mg/kg of ideal body weight is the usual induction agent in the United States, with succinylcholine about 1 mg/kg for relaxation. The bite block goes in after induction and before the stimulus. Hyperventilate to an EtCO2 near 30 mm Hg — it enhances seizure activity, blunts the heart rate rise and reduces post-ictal delirium. If the seizure is inadequate, ketamine 1.3 mg/kg has less anticonvulsant effect than methohexital.

ECT and what to have drawn up - Labetalol, esmolol or nitroglycerin for the sympathetic surge, particularly in patients with demand ischemia; underlying cardiac disease is the commonest comorbidity behind ECT complications. Break a seizure running past 120 seconds with more induction agent or a benzodiazepine. Ketorolac 10 mg IV treats the post-ECT headache that 48% to 85% of patients get.

Major depressive disorder (MDD) is diagnosed when persistently low mood or anhedonia, plus neurovegetative changes in sleep, appetite, concentration and psychomotor activity, cause social or occupational impairment. Lifetime prevalence runs 5% to 17%, averaging about 12%, and is roughly double in women.

The older monoamine model of deficient serotonin, norepinephrine and dopamine signaling has widened to include GABA and glutamate. That matters to you because every drug class these patients take works on a transmitter system anesthesia also touches. The depression itself rarely changes the plan; the antidepressant does. MDD also aggravates diabetes, hypertension, COPD and coronary artery disease, and comorbid substance use, panic and anxiety disorders are common enough that the medication list is usually longer than one drug.