Answers to anesthesia questions
Written by a practicing CRNA and cited to their source. These are drawn from the same reference content that ships inside Helix Anesthesia.
Anesthetic considerations in severe COPD
Expiratory flow limitation drives everything: induction agent choice, ventilating for auto-PEEP, reversal and extubation, and the phrenic palsy an interscalene block causes.
Anesthetic considerations for valvular heart disease
Lesion-by-lesion hemodynamic goals, grading and perioperative risk in aortic stenosis, valve intervention before noncardiac surgery, neuraxial technique, and the HCM mimic.
IV agent selection: hypertensive emergency and rate control in atrial fibrillation
Matching the IV antihypertensive to the target organ, the acute rate-control agents for atrial fibrillation, and what reduced ejection fraction or heart failure removes from both lists.
Anesthetic considerations for pulmonary hypertension
Right ventricular physiology, what raises pulmonary vascular resistance, nitrous oxide, separation from bypass, and inotrope choice.
Intraoperative hypotension: differential, management, and MAP targets
What mean arterial pressure to defend and why, the causes phase by phase, the first- and second-line drugs, and the point at which a routine pressor becomes a rescue problem.
Why oxygenation fails on one lung
Hypoxic pulmonary vasoconstriction, shunt versus dead space, one-lung ventilation and atelectasis — why supplemental oxygen fixes one of them and not the others.
Why the circulation fails under anesthesia
Right ventricular failure, coronary supply and demand, the three causes of hypotension, and why vasoplegia after bypass resists catecholamines.
Why regional blood flow fails
The organs a normal blood pressure does not protect: splanchnic, renal, hepatic and uteroplacental, and why the number lies.
What INR is safe for a spinal or epidural?
There is no single number, and the one everyone quotes is for the wrong thing — 1.5 is the catheter removal threshold, not the placement standard.
Which nerve blocks are safe on anticoagulants?
ASRA holds deep plexus blocks to the neuraxial intervals and does not classify the rest — which is the gap the Tsui advisory exists to fill.
Drug-eluting stents: how long before surgery?
The single number most of us memorized is gone. The 2024 guideline replaced it with two, and which one applies depends on why the stent was placed rather than what kind of stent it is.
Does one dose of etomidate have long-term consequences?
A 2013 study found 2.5 times the odds of 30-day death, and no randomized trial since has reproduced it — including one that infused the drug for four hours. The signal that did replicate is pneumonia, not death.
Intrathecal morphine: who follows the patient for 24 hours?
The 24-hour requirement is real and federal — and it is a requirement on the unit, not an assignment to anesthesia. Plus the 48-hour rule it keeps getting confused with.
What to tell your anesthesia provider before surgery
The plain-language hub: which medications actually matter, which conditions change the plan, and the one thing almost nobody brings.
GLP-1 agonists and anesthesia: hold or continue?
The guidance reversed inside eighteen months. Why the one-dose hold never made pharmacologic sense, and what replaced it.
Buprenorphine and surgery: continue, don't hold
The recommendation reversed. Why the old practice rested on a misreading, and why the ceiling effect is not a safety net for what you add.
Cannabis and anesthesia: what you should tell us
Not a legal question, a dosing one — 47 mg more propofol on average, plus the airway and postoperative pain effects.
POTS and anesthesia
Fasting is the biggest modifiable risk, and it is the one thing the standard pathway gets wrong for these patients.
Mast cell activation syndrome and anesthesia
No society guideline exists. Which agents release histamine, why MCAS is not anaphylaxis, and why the patient’s own list beats any table.
Methemoglobinemia: recognition and treatment
The saturation gap, why the pulse oximeter sticks near 85%, methylene blue dosing, and why the G6PD question is not the settled no it is usually taught as.
Cricoid pressure: does it actually work?
The IRIS trial is misreported in both directions — it did not show cricoid pressure works, and it did not show it doesn’t. Plus where the esophagus actually is.
Rocuronium vs succinylcholine for RSI
Succinylcholine gives better intubating conditions — except at the dose rocuronium is actually given for RSI, where the difference disappears.
Video vs direct laryngoscopy: what DEVICE showed
A 14-point absolute improvement in first-attempt success, stopped early for efficacy — and the population caveat that decides whether it applies to you.
Perioperative steroid stress dosing: what's current
The 300 mg/day regimen came from 1950s case reports about stopping steroids, not trials about escalating them. Who needs cover and who just needs their usual dose.
Sugammadex dosing: 2, 4 and 16 mg/kg
The dose is the easy part. The re-dosing intervals, actual body weight, and the contraceptive counseling that has to happen before discharge.
Vasopressor equivalents: why the formulas disagree
Norepinephrine equivalence is a research convention, not a pharmacologic fact — and phenylephrine’s factor varies fifteen-fold across the trials.
Why pediatric airway sizing formulas fail
The best landmark is correct under half the time, the formulas name sizes that do not exist, and the depth rule has a trap in it.
Anesthetic considerations for Ehlers-Danlos syndrome
Why the subtype decides the anesthetic, what the 2026 randomized trial showed about local anesthetic resistance, and the mechanical injuries that are the ones that actually happen.
Does ondansetron prevent spinal hypotension?
The Bezold–Jarisch mechanism, what thirteen randomized trials actually showed, and why it supplements a vasopressor rather than replacing one.
CABG anesthesia, step by step
On-pump bypass as three transitions with an interval between them — and the pre-bypass window where the disease is present and the fix is not yet.
TEE: what it is, and how to manage the anesthetic
Why a diagnostic TEE is a harder sedation assignment than its scheduling suggests: deep enough to tolerate the probe, awake enough to protect the airway.
Clopidogrel hold time before neuraxial and pain procedures
Three societies, three intervals — 5-7, 6, and 7 days — plus the restart nobody writes down and the narrow case where platelet function testing actually applies.
Local anesthetic maximum doses
Every agent, plain and with epinephrine, mg/kg and absolute cap, each cited to its package insert — plus the liposomal bupivacaine rules that cause LAST, and the lipid doses for when it happens.
Anesthetic considerations for Myasthenia Gravis
Inverted relaxant responses, why avoiding relaxants outperforms reversing them, and how badly the Leventhal score actually performs on validation.
Spinal anesthesia in elderly patients
Why the technique choice is individualized rather than settled, and what actually decides it — anticoagulation timing and hypotension in the volume-depleted.
Reference information for licensed clinicians and students. Not a medical device. Verify against institutional protocol and current package inserts.