Thymectomy

Baseline before induction - attach quantitative neuromuscular monitoring and record a control response while the patient is still awake. A myasthenic junction is already partly blocked, so a twitch during the case means nothing unless you know where it started.

Sensitivity to non-depolarizers - a conventional intubating dose can produce block lasting hours. If a relaxant is genuinely needed, give a small fraction of the usual dose, pick an agent cleared independently of organ function, and titrate to the monitor.

Resistance to succinylcholine - receptor loss makes depolarizing block harder to achieve, so a larger dose is needed if you use it, and anticholinesterase therapy prolongs its duration by inhibiting plasma cholinesterase.

A technique without relaxants - an inhalational induction, or propofol with a short-acting opioid, usually gives intubating and operating conditions on its own. Volatile agent on top of the baseline weakness relaxes enough for this operation.

Reversal and residual block - do not extubate on clinical impression. Confirm recovery quantitatively and set the reversal strategy against current guidance rather than habit, because residual weakness here is indistinguishable from the disease itself.

The morning pyridostigmine dose - in mild disease it is commonly held or halved so the cholinergic picture stays clean. A patient with severe disease and marked dependence takes the usual dose, because withdrawal buys bulbar weakness before induction.

Steroids and immunosuppressants - continue chronic steroid cover and plan a perioperative supplement, but a first exposure in a steroid-naive patient can transiently worsen weakness. Azathioprine antagonises block and ciclosporin can prolong it.

Preoperative plasma exchange - a course beforehand buys days to weeks of strength in refractory disease. Leave a day between the last exchange and the operation to restore clotting factors, and expect plasma cholinesterase to be low afterwards.

Drugs that unmask weakness - magnesium, aminoglycosides, calcium channel blockers and several antidysrhythmics depress transmission further. Hypokalemia, hypophosphatemia and hypothermia do the same, so keep the patient warm and the electrolytes normal.

Predictors of postoperative ventilation - long disease duration, a high daily anticholinesterase requirement, coexisting lung disease, a low vital capacity and previous respiratory failure all raise the odds. Get baseline spirometry and warn the patient.

Approach sets the anesthetic - a sternotomy is the painful, fully controlled version and a collar incision is not. One-lung ventilation is usually unnecessary for a thymectomy, but confirm it: a double-lumen tube is sometimes still requested.

Criteria for extubation - sustained five-second head lift, inspiratory force more negative than -25 cmH2O, tidal volume above 5 mL/kg, quantitative confirmation of recovery, fully awake. Keep measuring inspiratory force and vital capacity afterwards.

Myasthenic versus cholinergic crisis - anticholinesterase requirement usually falls once the gland is out, so the old dose can tip into overdose. Salivation, cramps, fasciculations and small pupils mean cholinergic excess; dilated pupils mean weakness.

Analgesia that does not sedate - a sternotomy needs a real plan and a collar incision does not. Build it around regional and non-opioid components, because respiratory depression on top of a failing junction is what returns these patients to the ventilator.

The thymus is the engine room of the autoimmune attack in myasthenia gravis (MG), an antibody-mediated disorder of the postsynaptic neuromuscular junction that produces fatigable weakness of ocular, bulbar, limb and respiratory muscles. More than 85 percent of myasthenics have an abnormal thymus, and 10 to 50 percent of patients with a thymoma develop MG, so the gland is removed both to induce remission and to take out a tumor. Severity is graded by the Osserman scheme, from ocular symptoms alone through progressive bulbar and systemic involvement. Because acetylcholine receptors are already reduced in number and occupied by antibody, the junction sits partly paralyzed before any drug is given. That single fact, not the chest, is what the anesthetic is built around.

Approach - a full median sternotomy allows removal of all anterior mediastinal tissue including small thymic rests. An upper sternal split limited to the manubrium, a transcervical collar incision, or a thoracoscopic or robotic port set trade some completeness for far less tissue injury.

Positioning for the limited approaches - the neck is extended over a roll placed between the shoulder blades so the cervical extensions of the gland can be reached from above, and a special retractor lifts the sternum to open the anterior mediastinum.

Dissection - the gland is mobilized off the pericardium and innominate vein, its attachments cauterized, and the thymic vein clipped where it drains directly into the innominate vein.

Phrenic nerves - both run along the lateral edges of the dissection and are deliberately preserved, because injury turns a well patient into a ventilation problem.

Pleura - the mediastinal pleura, usually on the right, can be entered during mobilization, and a chest tube is placed if it is.

Closure - the thymic bed is drained with a small suction drain, and the patient's own preoperative medications are restarted as early as possible.

Two very different operations share this booking. A myasthenic patient having a transcervical or thoracoscopic thymectomy has a small anterior neck or port-site wound and a pain score around two; a full sternotomy for a bulky thymoma sits at the other end and drives the figures given here. A large thymoma can also compress the airway, great vessels or heart, and that patient is managed as an anterior mediastinal mass rather than as a thymectomy - ask about positional dyspnea and orthopnea before you plan the induction.