Anesthesia Flashcards
What is the Mallampati class in this image? https://images.cram.com/images/upload-flashcard/47/88/15/33478815_m.jpg
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Name two inhalation anesthetics and one depolarizing muscle relaxant which trigger MH
– All the inhalation anesthetics can cause MH: desflurane, sevoflurane, isoflurane, methoxyflurane halothane, enflurane\n\n\n– Depolarizing muscle relaxant: succinylcholine
Indications for a difficult intubation
– Mallampati of 3 or 4\n– Mento–hyoid distance of less than 3 finger breadths\n– Reduced degree of head extension (<90 degrees)\n– Reduced jaw protrusion
What are the predictors of poor bag mask ventilation
Beard\nObese (>26)\nNo teeth\nElderly (>55)\nSnores
Why does CPAP use before surgery improve outcomes
Consistent use of CPAP, before and after surgery, as well as in hospital, reduces the risk of peri–operative complications.
Choosing Wisely:\nDon’t order these 2 types of tests for asymptomatic patients undergoing low–risk non–cardiac surgery.
Lab tests\nElectrocardiograms
Choosing Wisely:\nDon’t order these 2 types of tests for asymptomatic patients undergoing low–risk to intermediate risk non–cardiac surgery .
Echocardiogram\nCardiac stress testing
Choosing Wisely: \n\nDon’t order a baseline chest X–ray in asymptomatic patients, except as part of ______ or __________evaluation.
Don’t order a baseline chest X–ray in asymptomatic patients, except as part of surgical or oncological evaluation.
Describe the ASA Physical Status Classification System (1 to 5)
- Healthy\n2. Mild systemic disease (smoker, well controlled DM)\n3. Severe systemic disease that is not incapacitating (non recent hx of MI, poorly controlled HTN)\n4. Incapacitating disease that is a threat to life (morbid obesity, ESRD without dialyses, recent MI)\n5. Moribund, not expected to survive more than 24 hours
Why is spinal anesthetic contraindicated in aortic stenosis?
Post spinal hypotension
What are the two life events promoting smoking cessation.
Pregnancy and Surgery\n\n\n (Smokers experience bronchospasm, increased secretions which increase pneumonia risk, lower oxygen delivery to surgical site increases infection risk)
What are the As of Anesthesia
Awareness (unconscious)\nAmnesia\nAnalgesia (remove subconscious pain)\nAkinesia \nAnxiolysis
Stages of Anaesthesia
Preparation\nInduction\nMaintenance\nEmergence \nRecovery
When is rapid sequence induction (RSI) used?
When the patient is at increased risk for aspiration (e.g. decreased integrity of lower esophageal sphincter)\nUsed in emergencies, but only because the person has not been NPO
What are the components of a rapid sequence induction?
Ready the suction apparatus\nPre–oxygenate the patient (no bag masking)\nInduction with pre–calculated induction agent\nIntubating dose of depolarizing muscle relaxant (succinylcholine or high dose rocuronium). \nAssistant applies cricoid pressure (Sellick’s maneuver) \n\nIntubation of trachea, cuff inflation and verification of proper tube position.
What is the purpose of the Sellick Maneuver?
Occludes the esophagus to reduce the risk of passive aspiration
Where is the cricoid cartilage, find it on yourself
https://images.cram.com/images/upload-flashcard/53/52/92/33535292_m.jpg
Why shouldn’t people take diuretics and ACE inhibitors the day of surgery
Their NPO status is already putting them at an increased risk of hypovolemia and hemodynamic instability, no need for an additional diuretics and anti–hypertensives.
IV induction agents
propofol, ketamine,thiopental or etomidate, (followed by non depolarizing muscle relaxant)
What are some reasons to avoid using Succinylcholine in a patient?
Patients with hyperkalemia and renal failure\nPatients with history/ family history of malignant hyperthermia\nPatients with pseudocholinesterase deficiency(this is not an exhaustive list)
Drug classes used in the maintenance phase
Inhaled agents, opioids, vasoactive medications, and non–depolarizing muscle relaxants (NDMR)
What inhaled drugs are used for anesthesia maintenance?
Volatile agents (desflurane, isoflurane, sevoflurane)\nNitrous oxide
What is the Minimum Alveolar Concentration?
MAC refers to the concentration of the inhaled agent in alveolar gas necessary to prevent movement of 50% of patients when a standard incision is made
Which factors are associated with a lower MAC in a patient?
Advanced age, pregnancy, hypothermia, alcohol intoxication, depressant drugs (muscle relaxants, opioids, benzos, central antihypertensives)
Risk associated with volatile agents
Trigger malignant hyperthermia
Risks associated wtih Nitrous oxide (N2O)
Expands volume of gas containing spaces because it diffuses so easily across membranes. \nAs a result, increases size of pneumothorax, emphysematous bleb, distended bowel loop.
Which inhaled agent is best for an extended surgery in an obese patient.
Desflurane is a better choice, it is less fat soluble so has a faster onset and offset.\nOn the other hand, sevoflurane is fat soluble, and is absorbed over the extent of a long surgery.
What benefit does sevoflurane have in the context of COPD?
Bronchodilating effect and less irritating to airway.
Why are opioids given in the maintenance phase?
Provide analgesia, and to reduce the requirement of other maintenance agents.
What opioids are used intraoperatively?
fentanyl, sufentanil, remifentanil and alfentanil because they are short acting, giving the anesthesiologist more control.
What is the max N2O you can give
70% (leave 30% for O2)
When are opioids generally admistered?
As a loading dose before induction. Helps blunt response to intubation and provides baseline plasma level for anaesthetic throughout the surgery.
What anticholinesterase is most frequently used to reverse neuromuscular blockade?
neostigmine – acts by inhibiting acetycholinesterase enzymes, and thereby increasing the amount of acetylcholine in the neuromuscular junction
How does a neuromuscular junction work?
stimulation causes ACh to be released from presynaptic neuron —>diffuses and binds to AChR on post–synaptic motor end plate —> Ca release—> muscle excitation + contraction. \n\n ACh released from AChR —> degraded by ACh–esterase enzyme.
How does a neuromuscular blockade work with Rocoronium? Succinylcholine?
Rocuronium\nRocuronium binds to receptor so acetylcholine cannot bind. It is non depolarizing, so it does not trigger the release of calcium and the resulting muscle contraction.\nSuccinylcholine\nAlso binds to acetycholine receptor. However, it is depolarizing, meaning that it actually triggers a muscle contraction. However, after that contraction ends no additional contraction is possible because succinylcholine cannot be degraded by ACh–esterase enzyme
How does a neuromuscular blockade reversal work?
Acetylcholinesterase breaks down acetylcholine. Acetylcholinesterase inhibitors (e.g., neostigmine) prevent this breakdown, increasing acetylcholine levels. The additional acetylcholine out competes the Rocuronium.
Benefit of sugammadex
Removes rocoronium from acetylcholine receptor (exact mechanism unknown) . Works when neostigmine won’t.
What is the “Train of Four”
Device delivers four electrical stimuli to muscle.\nMuscle response as measured by machine suggests the degree to which acetylcholine receptors have been blocked \nFull blockade (less than two twitch responses) suggests neostigmine cannot yet help acetycholine to out compete rocuronium
Side effects of neostigmine
Parasympathetic response: bradycardia and SLUDD – salivation, lacrimation, urination, defecation, digestion\nNB: excess salivation can present an aspiration risk
Four Drugs for Post Operative Nausea and Vomiting
Metoclopramide\nOndansetron\nDexamethasone\nGravol
What are the stages of post op pain management? Why is pain management important?
Walk down the WHO analgesia ladder, starting with intense analgesia to prevent chronic pain syndromes and avoid the negative hemodynamic effects of pain.
