TL Pages 6-10 Flashcards
What is the effect of preop clonidine on anesthesia?
Decreases MAC but increases risk of bradycardia and hypotension.
What are key treatments for venous air embolism (VAE)?
Flood surgical field with saline, place patient head-down, compress jugular veins.
What is the insulin-dextrose treatment for hyperkalemia?
10 units IV insulin + dextrose unless glucose ≥250 mg/dL; lowers K+ by 0.5-1 mEq/L.
How does ketorolac affect renal function?
Inhibits afferent renal vasodilation, reducing GFR, especially after 5+ days.
Does epinephrine addition change local anesthetic onset?
No significant effect on block onset time.
What factors increase the onset of local anesthetics?
↑ Concentration, lipid solubility, pH; ↓ pKa.
What is a common response to a second dose of succinylcholine?
Bradycardia, especially in children due to muscarinic receptor activation.
What limits flumazenil effectiveness long-term?
Short half-life can cause benzodiazepine sedation to recur.
Which central line has higher infection risk?
Nontunneled central venous catheters.
Why is pulse oximetry limited on 100% oxygen?
Poor indicator of ventilation.
What does Poiseuille’s law say about flow in vessels?
Flow ∝ radius^4; radius has greatest impact.
Why are newer CO2 absorbents safer?
Lack strong bases that produce CO with volatile agents.
What % receptor occupancy reduces TOF count?
About 70%.
How does fresh gas flow affect rebreathing?
↓ FGF = ↑ rebreathing, ↓ waste gas scavenging.
What is the defining feature of a closed circle system?
FGF matches metabolic demand; no scavenging required.
Do Cobra and Tulip airways protect against aspiration?
No; they are cuffed pharyngeal sealers without esophageal occlusion.
Most important factor for spinal block level?
Baricity (e.g. hyperbaric bupivacaine).
How is a local anesthetic made hyperbaric?
By adding dextrose.
Signs of thoracic duct injury after CVC?
Left-sided swelling, unilateral effusion, rising ventilator pressures.
Where are cardiac parasympathetic fibers found?
SA and AV nodes; they affect chronotropy.
Which local anesthetics are most affected by epinephrine?
Lidocaine, mepivacaine, and chloroprocaine.
How long should clopidogrel be held before neuraxial block?
5–7 days.
Why does etomidate cause injection pain?
Hyperosmolarity; prevent with lidocaine, fast injection, large vein.
What side effect does normeperidine have?
CNS stimulation: myoclonus and seizures.
What is the intracellular concentration of potassium?
157 mOsm/L.
What EEG pattern is seen in sedation?
Alpha waves (8–13 Hz), BIS 65–85.
Formula for pulmonary vascular resistance (PVR)?
PVR = [(PA mean - PCWP) / CO] * 80.
How is vascular resistance calculated?
Resistance = Pressure / Flow (Poiseuille’s Law).
How does metabolic acidosis affect CO2 curve?
Left shift without slope change.
Why are infants prone to bradycardia on laryngoscopy?
Predominant parasympathetic tone.
Best marker of liver synthetic function?
INR or PT, reflects factor VIIa (short half-life).
What are ketone bodies and when are they formed?
Formed from free fatty acids during fasting; used by brain.
How does nitrous oxide provide anesthesia and analgesia?
NMDA inhibition, μ-receptor activation, GABA-A activation.
What is mannitol’s effect in heart failure?
Increases BP, CO, and PCWP.
Main cardiac risks of prolonged propofol?
Bradycardia, acidosis, lipidemia, rhabdomyolysis, heart failure.
What is ED95 in neuromuscular blockade?
Dose that produces 95% twitch block in 50% of individuals.
Which volatile agent potentiates NMBs most?
Desflurane > sevoflurane > isoflurane > halothane.
What is sevoflurane metabolized into?
Inorganic fluoride and hexafluoroisopropanol.
What makes diltiazem unique among CCBs?
Acts on cardiac and smooth muscle; ↓ PVR and coronary vasodilation.
What defines hypertensive urgency pre-op?
BP >180/110 mmHg without end-organ damage.
Which anesthetics cause methemoglobinemia?
Benzocaine, prilocaine, lidocaine, tetracaine.
Which opioid is metabolized by plasma esterases?
Remifentanil.
What maintains hepatic perfusion in buffer response?
Portal flow modulates hepatic artery via adenosine.
What is the hepatic O2 supply ratio?
Portal vein 75% of flow, 50% O2; hepatic artery 25% flow, 50% O2.
Which hormones affect hepatic/portal vasculature?
Glucagon (vasodilation), Ang II & vasopressin (vasoconstriction).
How to estimate time to desaturation during apnea?
[FRC ÷ O2 consumption] * %O2 in FRC.
How does PaCO2 regulate CBF?
↑ PaCO2 → ↓ CSF pH → vasodilation via prostaglandins and NO.
How does CSF pH affect ventilation?
Acts on central chemoreceptors in medulla.
What causes phase 2 of cardiac action potential?
Ca2+ influx via L-type calcium channels.
What are signs of cerebellar dysfunction?
Intention tremor, dysarthria, nystagmus.
What is the final step in ammonia elimination?
Conversion to urea in liver.
What are signs of hepatic encephalopathy?
Asterixis and confusion due to hyperammonemia.
How does pH affect calcium binding?
Alkalosis ↑ binding (↓ ionized Ca); acidosis ↓ binding.
How does protein binding affect hepatic metabolism?
↑ Binding = ↓ clearance; binding is ↓ in liver/renal disease.
Which conditions increase plasma protein levels?
Obesity, pregnancy, burns.
How does nitrous oxide cause bowel distention?
Longer administration and higher concentration.
What blocks are potentiated by neostigmine?
Phase I; neostigmine may antagonize phase II.
What is hepatorenal syndrome?
Renal hypoperfusion from portal HTN → splanchnic vasodilation.
What is the Meyer-Overton rule?
Anesthetic potency ∝ lipid solubility in olive oil.
What can cause hoarseness after intubation?
Arytenoid subluxation; risk ↑ with poor muscle relaxation.
How does dexmedetomidine affect CO2 response?
Preserves hypercapnic response; good for OSA/hypoventilation.
What are systemic effects of dexmedetomidine?
Sedation, analgesia, bradycardia, ↓ CBF, mimics non-REM sleep.
How does aspirin inhibit platelets?
Irreversibly blocks COX → ↓ thromboxane A2.
What do prostacyclins do?
Vasodilation and platelet activation (not aggregation).
Main lung immune cells?
Pulmonary alveolar macrophages; neutrophils in smokers or lung injury.
Treatment for vasopressor extravasation?
Hyaluronidase, phentolamine, saline irrigation, stellate block.
Most common periop nerve injury?
Ulnar nerve; avoid elbow flexion, pad medial epicondyle.
Best predictors of fluid responsiveness?
Dynamic measures: SVV >13%, PPV better than CVP.
What defines posterior ischemic optic neuropathy (PION)?
Sudden painless vision loss, afferent defect, no disc edema.
