General Anesthesia and Airway Mgmt- Exam 1 Flashcards
d-Tubocuraine
Slow onset (6m) Long duration (90m) Causes hypotension=do not give to hypotensive pt Causes histamine release and skin flushing
Atracurium
Ester hydrolysis metab (plasma)
Not metab thru liver or kidneys=safe for administration in pt w/ kidney and/or liver dz
Onset=5m
Duration=30m
Succinylcholine
Rapid onset (30-60s) Short duration (5m) Metab by serum (pseudo) cholinesterase (if pt lacks enz, DO NOT GIVE=DEATH!)
What are the SEs a/w Succ?
Bradycardia Fasciculations Incr gastric pressure (No pts w/ GERD) Incr intraocular pressure (No pts w/ glaucoma) Incr intracranial pressure Incr K+ (No pts w/ K+ >7.5)
Pancuronium
Onset=7m
Duration 60-75m (avg length of podiatry case)
Processed in liver and excreted by kidneys
Given after pt is intubated
Used for long term relaxation in long cases
Roncuronium
Onset=3m
Duration=30-50m
Good replacement for Succ
Vercuronium
Onset=5-6m
Duration=30-60m
Metab in liver, excreted in kidneys (No pts w/ kidney or liver dz)
What are the NMJ reversal agents?
Anticholinesterase:
Neostigmine
Edrophonium
Phyostigmine
What is the Pathophys of Malignant Hyperthermia?
- Decr Ca++ uptake by sarcoplasmic reticulum
- Leads to high intracellular [Ca++]
- Aerobic and Anaerobic cell turnover
- Leads to excess heat, CO2, and lactic acid
How will a pt present w/ MH?
Fever, unexplained tachycardia and tachypnea, failure of masseter muscle relaxation
How is MH dx?
- Muscle biopsy
2. Serum CPK (creatinine phosphokinase) elevated
What drug is given to tx MH?
Dantrolene:
1-2 mg/kg
Nose and Mouth
Fxn: warm and humidify air
Inn: CN V (trigeminal), CN IX (glossopharyngeal)
Pharynx
Fxn: connect oral and nasal cavities to esophagus and larynx
Inn: CN IX and X (vagus)
Larynx
Fxn: modulation of sound; separates esophagus from trachea during swallowing
Inn: CN X
Location: btwn C3-C6
Trachea
Location: C6-T5
Supported by 16-20 cartilages (Cricoid has full ring structures; remainder have horseshoes)
Mallampati Class I
Soft palate, fauces, uvula, and tonsillar pillars are visible
Mallampati Class II
Soft palate, fauces, and uvula visible
Mallampati Class III
Soft palate and base of uvula visible
Mallampati Class IV
Soft palate NOT visible
Cormack and Lehane Score: Grade I
Most of the glottis is visible
Cormack and Lehane Score: Grade II
Only posterior portion of glottis visible
Cormack and Lehane Score: Grade III
The epiglottis visible, but NO PART of the glottis can be seen
Cormack and Lehane Score: Grade IV
No airway structures visualized
What is the primary problem of airway mgmt?
The inability to oxygenate, ventilate, and prevent aspiration (or a combo of these factors)
What are the boundaries of the facemask (for ventilation)?
Bridge of the nose
Upper border aligned w/ pupils
Sides seal lateral to nasolabial folds
Bottom seals between lip and chin
Endotracheal intubation technique
- Raise table so pt is at height of xyphoid cartilage of the anesthesiologist
- Elevate and extend head
- Align oral, pharyngeal, and laryngeal axes
- Apply pressure to cricoid cartilage
- Blade, tube, and check for placement
When is Fiberoptic Endotracheal Intubation indicated?
- Known that pt will be difficult to intubate by direct laryngoscopy
- Unstable cervical spine
What is the ratio of compressions:breaths in compression-only CPR?
30:2
What drugs are used to control A-flutter?
Beta blockers and Ca++ channel blockers
What drugs are used to control V-tach?
Lido, Procainamide, Bretyllium
What drugs are used for V-fib?
Epi, Lido, Bretyllium, Mag Sulf, and Procainamide
What drugs are used in Asystole?
Epi, Atropine, and Sod Bicarb
What are causes of asystole?
Hypoxia, hypokalemia, hyperkalemia, hypothermia, acidosis, and drug OD
What is normal body pH?
7.4
What are causes of metabolic acidosis?
Renal failure
Lactic acidosis
Ketoacidosis
Hypokalemia
What are causes of metabolic alkalosis?
Vomiting
Mineralcorticoid excess
What are causes of respiratory acidosis?
Hypoventilation
CNS depression
COPD
Guillen-Barre Syndrome
What are causes of respiratory alkalosis?
Anxiety Sepsis Lung Dz Hypothyroidism Liver dz Pregnancy
What is the definition of Local Anesthesia?
Drug induced REVERSIBLE blockade in a restricted region of a nerve fiber
What are the two types of LAs?
Amides and Esters
What is the common structures shared btwn LAs?
Lipophilic aromatic ring–amide/ester–hydrocarbon chain–2ry/3ry amine (hydrophilic)
What is the least toxic amide LA?
Lidocaine
What is the longest acting amide LA?
Bupivicaine
What is the duration of action of Lidocaine?
2 hours
Which amide LA has the most VC properties?
Prilocaine
What is the relationship btwn Ropivicaine and Bupivicaine?
They are both long acting but Ropivicaine is less cardiotoxic
What is a major complication of Prilocaine?
Fetal methemoglobinemia
Are LAs weak acids or base? What is their pKa?
Weak bases
8-9
Why are ester LAs not used very ofter?
Because they are short acting and take longer to take effect
What is the oldest, widely known, useless LA? Ester or amide? Why is it useless?
Procaine (Novocaine)
Ester
It’s pKa is 9.1=very long onset (relative to other LAs)
What is the MOA of LAs?
Block nerve conduction by reducing influx of Na+ into cytoplasm
Upon administration of LA, is it in its ionized or unionized form? Why? Acidic or basic?
Unionized
Because in this form it is able to penetrate the plasma membrane (lipid)
Acidic bc more stable and water soluble
What form, ionized or unionized, produces the actual block?
Ionized form
T or F. LA blocks occur from inside out?
T. LAs must penetrate the lipid membrane, ionize, and then bind to Na+ channels to prevent influx
How is pH, pKa, rate of diffusion, and effect of LA related?
If pH=pKa then the rate of diffusion would be rapid, and therefore the effect of the LA would be rapid. Conversely, higher pKa:pH ratio=slower diffusion, etc.
What effects the speed of onset of LAs?
Type of nerve fiber [LA] Degree of lipid solubility Tissue pH Degree of protein binding
How man successive Nodes of Ranvier must be blocked for a LA to be effective?
3
In a non-myelinated nerve, how long of a segment must be blocked for a LA to be effective?
5mm
Arrange in order the type of neurological stimuli that is anesthetized first to last:
Temp, pressure, motor, touch, sharp pain
Sharp pain->temp->touch->pressure->motor
**Recovery usually happens in the reverse order
What is anesthetized first, cold or warm sensation?
Cold
Greater protein binding increases or decreases duration of LA?
Decreases
Where are amide LAs metabolized?
Liver
Where are ester LAs metabolized?
Serum
What do vasoconstrictors do to LAs?
Decr absorption into blood stream=prolong effects
Incr local effects/duration
Decr risk of toxic effects
What are some common VC agents?
EPINEPHRINE<–must know this one!!!
Phenylephrine
Levonorfedrin
What are common drug interactions w/ LAs? (in particular, esters)
Sulfur-containing drugs: Abx (Bactrim) Diuretics (Acetazolamide) Anticonvulsants NSAIDs
How deep should the needle go upon injection of a LA?
Deep enough while leaving 1/4” exposed
What is the max dose of Lido 1% plain?
4.5 mg/kg, not to exceed 300mg
What is the max dose of Lido 1% w/ Epi?
7 mg/kg, not to exceed 500mg
What is the max dose of Mepivicaine 1% plain?
7.5 mg/kg, not to exceed 400mg
What is the MOA of propofol?
Potentiating the Cl- current mediated thru the GABA receptor complex
At what dose and for how long do you need to take propofol to get Propofol Infusion Syndrome?
> 4 mg/kg/hr for 24h
What is the general dose for propofol? For peds pts?
- 1.0-2.5 mg/kg
- 2.5-3.5 mg/kg
What are barbituates used for?
Induction of anesthesia prior to propofol
What is the MOA of barbituates?
Enhancement of inhibitory NTs (i.e., GABA receptors)
In terms of the CV system, what is a difference btwn propofol and barbituates?
Propofol is a vasodilator and barbituates are vasoconstrictors
What are the two examples of barbituates used? Doses?
Thiopental 3.0-5.0 mg/kg IV
Methohexital 1.0-1.5 mg/kg IV
Where are barbituates metabolized?
Liver, via oxidation (methohexital is cleared more rapidly)
Where are barbituates excreted?
Kidney, bile via conjugation rxns
Where is propofol metabolized?
Mainly the liver, but lungs 30%
Where is propofol excreted?
Kidneys
What are the examples of Benzos used?
Diazepam, lorazepam, midazolam
What drug is a benzo antagonist?
Flumazenil
Of the benzos used, which is the most lipophilic?
Miazolam
What is the MOA of benzos?
- Actication of GABAa receptor
- Enhancement of GABA-mediated Cl- currents
- Hyperpolarization of neurons and reduced excitability
Benzos have what effect on gamma-subunit receptors?
Anxiolysis and muscle relaxation
Where are benzos metabolized?
Liver
What are benzos used for, clinically?
- Pre-op meds (peds pts)
- IV sedation/induction of sedation
- Suppression of seizure activity
What drug produces a “cateleptic state” in patients?
Ketamine
What is the MOA of ketamine?
Inhibition of the N-methyl-D-asparate (NMDA) receptor complex
Which drug has caused unpleasant emergence rxns (i.e., hallucinations, out of body experiences) which has limited its use?
Ketamine
Compared to other drugs, Ketamine does what to systemic BP?
Increases
Where is ketamine metab?
- Liver
- Metabolite is active but less potent
Where is ketamine excreted?
Kidney
Ketamine has a high lipid solubility. What does that mean?
It has a rapid onset
What are some unique properties of ketamine?
Analgesia, stim of SNS, bronchodilation, minimal respiratory depression, and ability to use in uncooperative or mentally challenged pts
What is the MOA of etomidate?
Potentiation of GABAa-mediated Cl- currents
What must be done first before administration of etomidate?
Fluid/volume balance must be achieved bc BP lowering effects are exaggerated in the presence of hypovolemia
What drug inhibits 11B-hydroxylase, the enzyme that converts cholesterol to cortisol?
Etomidate
How is etomidate metab?
Ester hydrolysis
Where is etomidate excreted?
Kidney and liver (bile)
When is etomidate used clinically?
It’s an alternative to propofol and barbituates for rapid induction in pts w/ compromised myocardial contractility
Dexmedetomidine is in what class of drugs?
Selective alpha-2 adrenergic agonist
Where is dexmedetomidine metab?
Liver
Where is dexmedetomidine excreted?
Kidney and bile
What are the clinical uses of dexmedetomidine?
- Short term sedation of intubated and ventilated pts
- Sedation during awake fiberoptic tracheal intubation
- Sedation during regional anesthesia
What is Fentanyl?
A potent, synthetic narcotic opioid that produces analgesia
What is the MOA of Fentanyl?
Agonizes the mu-opioid receptor=inhibit pain NT release by decreasing Ca++ levels
What are the clinical uses of Fentanyl?
Adjunct to GA or RA, ER dislocation/relocations, post-op pain, peds pts
What opioid is 5-10X more potent than Fentanyl and is used during surgical procedures in opioid-dependent pts?
Sufentanyl
What classic drug regimen is used for Rapid Induction Anesthesia?
Thiopental + Succinylcholine
What drug is used in veterinary medicine?
Dexmedetomidine
Which drugs can be used in peds pts?
Propofol, Benzos, Ketamine, Fentanyl
What drugs cause a barbituate-induced histmaine release?
Thiopental and methohexital
Peri-op Meds:
-TCAs cause what?
- HYPOtension
- Incr/decr response to sympathomimetic (DOP, NE)
Peri-op Meds:
-What’s important regarding MAOIs?
- No meperidine of ephedrine=incr risk of serotonin syndrome
- Can cause severe HTN
- Hold 2 weeks prior to sx (MUST!!!!!!)
Peri-op Meds:
-Can you continue SSRIs prior to sx?
Yes
What are the importance of B-blockers, peri-operatively?
B-blockers are our friends! We do not want the pt to have an MI. If the pt has LV problems, they may be given 3 doses pre-op
What is the concern w/ ACEIs intra-op?
- May cause HYPOtension
- May stop 1 week prior to sx and be monitored intra-op
- 99.9% of time cardiologist will allow them to be continued (esp if using Local w/ MAC; but if using GA w/ a long case=may stop 1w prior)
When do you d/c ASA or Plavix prior to sx?
5-7d
What is the therapuetic INR pre-op?
2-2.5
If you are:
- Low risk for VTE
- Mod risk for VTE
- High risk for VTE
- When do you d/c coumadin?
- 4-5d prior to sx
- 4-5d and consider bridge therapy w/ LMWH (Fragmin or Lovenox) or unfractioned heparin 2-3d prior
- Bridge therapy; await hemostasis before restarting LMWH
If you have an urgent or major procedure, what is done for coumadin pts?
They are given IV/PO VitK or FFP w/ VitK to initaite clotting prior to procedure
If you have an urgent or major procedure, what is done for pts on ASA, Plavix, or both?
Transfuse w/ platelets or administer pro-hemostatic agent
Endocrine meds pre-op:
- Insulin?
- Insulin pump?
- Oral hypoglycemics?
- Insulin=hold a.m. dose
- Insulin pump=decr a.m./p.m. dose and give IV drip intra-op
- Oral hypoglycemics=d/c; sulfonureas may incr risk of MI; metformin may cause LACTIC ACIDOSIS=hold 24h-2d prior to sx
What do you do if pt is on OCP?
- If they are low risk for DVT=continue
- If high risk, d/c 4w prior to sx
If a pt is on steroid therapy, what do you do peri-op?
- MUST SUPPLEMENT! With sx, you are causing them incr stress so you don’t want their levels to fall too low.
- Give:
1. Cortisol 25mf pre-op
2. Solumedrol 100mg
What Vitamin should the pt d/c prior to sx? Why?
- Vitamin E
- Stop 1w prior due to risk of incr bleeding; also, do not want pt to go into tachy
Why hold the a.m. dose of tramadol pre-op?
Bc it may cause seizures and there’s an incr risk of itra-op drug interactions
What factors affect drug choice and dose peri-op?
Pts physical needs, pts psychological state, choice of anesthesia, and length of procedure
What is a common peri-op LA?
Lidocaine
What is a common benzo ANTAGONIST?
Flumazenil
What is SCIP?
- Surgical Care Improvement Project
- A nat’l quality partnership of organizations committed to improving the safety of surgical care thru the reduction of post-op complications
What is Measure 1 of SCIP?
Pre-op prophylactic abx to be administered w/in 1h prior to incision (2h for vanco or fluoroquinolones)
What is Measure 2 of SCIP?
Prophylactic abx selection for surgery pts. For podiatry=cefazolin, cefuroxime, or vanco. If B-lactam allergy=clinda or vanco
What is Measure 3 of SCIP?
Prophylactic abx d/c w/in 24h AFTER surgical end time
What is Measure 7 of SCIP?
Pts on B-blockers should receive their B-blockers prior to arrival or during the peri-op period
What pts are at high risk for aspiration of gastric contents?
Pregnancy, obesity, DM, GERD, hiatal hernia
What drugs are used to reduce pH?
- Anticholinergics=Atropine and Glycopyrrolate
- RANITIDINE=LASTS UP TO 9h!!!!
Why would you give a fluid volume reducer prior to sx?
These are usually given in emergency sx, bc it’s likely the pt has just eaten.
What is a fluid volume reducer?
Metoclopramide=dopamine antagonist
What are common uses for anticholinergic agents?
- Decr airway secretions
- Sedative and amnesic effects
- Anti-reflex bradycardia
What are some common anticholinergic drugs?
Scoplamine, atropine, glycopyrrolate
What is a anticholinergic reversal drug?
Physostigmine
What is a widely used H2 receptor antagonist?
Ranitidine=last up to 9h!!!! and less SEs than cimetidine
Must use clippers or razors in OR for getting rid of hair?
Clippers ONLY!
What drug is used as an antacid?
Sodium citrate=nearly 100% effective in elevating gastric pH if administered 30min prior to induction
Why is droperidol given?
It’s given at the end of procedure to prevent NV
Why is clonidine given?
Prevents HTN and bradycardia produced by intubation and surgical trauma
What is the most potent benzo?
- Lorazepam
- It can be used for same-day sx or in-house sx
What is a disadvantage to using diazepam as a sedative/hypnotic?
It has a long half-life (20-35h) so you don’t want them to have issues post-op
Why do you not want to give a benzo in a pt w/ liver dz?
Bc they are metabilized in the liver
Why is lorazepam “our friend”?
Bc it is eliminated in 10-15h and is 5-10X more potent than diazepam
What can be given to replace dexamethasone prior to someone coming out of anesthesia?
Droperidol=stronger than dexa
Which benzo has “no pain on injection”?
Lorazepam
Which drugs ARE NOT THE BEST for sedation?
OPIOIDS!!!!!!
What’s the big issue w/ benadryl, post-op?
Drowsiniess
What’s the big issue w/ opioids, post-op?
Constipation
How long does morphine take to take effect?
15-30min and lasts 4 4h
Where is meperidine metabolized?
Liver=do not give to someone w/ liver dz
What is the 1st Korotkoff sound?
Systolic pressure
What is the 5th Korotfoff cound?
Disatolic pressure
What is Malignant Hyperthermia?
- Incr in core body temp
- Genetic predisposition
- More common w/ GA
- Anticholinergics BLOCK sweating
- Incr BMR
- Initial signs=Incr HR and CO2
When is a Swan-Ganz catheter used?
When the pt is very sick. It’s good for infusion, cardiac pressure monitoring and CO measurements
On EKG, what type of “wave” indicates ischemia?
Inverted T-waves
On EKG, what type of wave indicates infarct?
ST segment elevation
On EKG, what does ST segment depression represent?
Subendocardial infarction
What type of nerve palsy are you worried about in the supine position?
Ulnar nerve palsy
What type of nerve palsy are you worried about in the prone position?
Brachial plexus palsy
What nerve issues are you worried about in the lateral decubitus position?
- Brachial plexus
- Lateral femoral cutaneous
- Common fibular
What antihistamines do you want to avoid in the geriatric population?
Promethazine, Chlorpheniramine, and Scopolamine
SNS produces what kind of response?
Adrenergic
PSNS produces what kind of response?
Cholinergic
SNS pre-ganglionic fibers use what NT?
Ach
PSNS pre-ganglionic fibers use what NT?
Ach
SNS post-ganglionic fibers use what NT?
NE
PSNS post-ganglionic fibers use what NT?
Ach
What are the 4 Anesthesia Stages?
- Analgesia
- Excitation
- Surgical Anesthesia
- Medullary Depression
What Anesthesia Stage do we want to obtain?
Stage 3=Surgical Anesthesia–>light to deep anesthesia, reduced muscle tone, incr loss of ocular reflex, no response to skin incision
What is the definition of sinus tachy? How is it tx?
- HR > 120
- B-blockers
What is the definition of sinus brady? How is it tx?
- HR < 60
- Atropine
What type of BBB is more clinically significant?
LBB. It’s seen in HTN, CAD, and LVH
What is essential in a pt w/ apnea during sx?
Maintenance and monitoring or airway
What does Halothane lack that causes ventricular arrhythmias?
An ether molecule
Why are anesthetics halogenated w/ fluorine better?
- Greater stability
- Resistant to metab
What is the main advantage of Halothane? Disadvantage?
- Faster induction and faster emersion
- Fulminant hepatic necrosis=halothane hepatitis
What are the advantages of Isoflurane? Disadvantages?
- NOT a/w cardiac arrhythmias, less metab than halothane and enflurane (stays in system longer), more rapid induction and emersion
- Pugnent=impractical for inhalation
What is the main disadvantage of Sevoflurane and Desflurane?
EXPENSIVE!!
What is the MOA (general consensus) of inhaled anesthetics?
Ion channels:
- Depress fxn of excitatory channels=prevent Na+ from entering neuron
- Enhance inhibitory channels=Cl- ions enter thru GABA channels and K+ ions leave thru K+ channels
Non-depolarizing Muscle relaxants are…(compared to Depolarizing MRs)
- More potent
- Have a longer onset (5-10min)
- Have a longer duration of action (30-90min)
What is the length of the Thyromental distance?
3 finger breaths
How far is the endotracheal tube inserted?
1-2cm past the vocal cords
During chest compressions (CPR), how far do you depress the sternum?
1.5-2 inches
During CPR, how many compressions/min?
100
ASA I
Normal healthy pt
ASA II
Pt w/ mild systemic dz; no fxnal limitation
ASA III
Pt w/ severe systemic dz, not incapacitating
ASA IV
Pt w/ severe systemic dz that is a constant threat to life
ASA V
A moribund pt who is not expected to survive w/o the operation
ASA VI
Pt who is already pronounced brain-dead and whose organs are being removed for transplant
ASA E
E=emergency, and is a modifier to the ASA classification system
What are the 4 groups of adverse medication reactions?
- Allergic (most common)=Abx
- Toxic=halothane hepatitis
- Pharmacologic=PONV from opioids or hypoventilation from sedatives
- Genetic=malignant hyperthermia
How long does a pt need to be NPO before sx?
At least 8 hours
If pt at risk fr gout, when is colchicine given?
pre-op, intra-op, and post-op
What is the most important factor in evaluating a pt’s EKG?
YOU MUST COMPARE IT TO THEIR MOST RECENT EKG (if applicable)
What are the 5 cardinal manifestations of anesthesia?
- Amnesia
- Analgesia
- Hypnosis
- Blunting of autonomic reflexes
- Muscle relaxation
What are some advantages to SAB (Sub-Arachnoid Block)?
- No airway manipulation
- Decr # and amount of meds used
- Reduction of surgical stress
- Ideal for many surgical procedures
What are some disadvantages of SAB (Sub-Arachnoid Block)?
- SNS blockade=HYPOtension
- Anxiety
- “Failed” block
- PDPH=Post-dural-puntcure-headache (usually young female, 20-40yo)
What valvular dz is contraindicated for SAB?
Aortic stenosis. Anything <1 for valve area
What type of block:
- is based on mg of drug delivered, and
- is also dependent on baricity
SAB (Sub-Arachnoid Block)
What is baricity? Give an example
Baricity=density of a substance compared to the density of the pt’s CSF
-e.g., If a LA is more dense than CSF=hyperbaric, and anesthetic will SINK
What type of block:
- is base on volume injected, and
- does NOT take into acct baricity
Epidural block
In the spine, where is LA usually injected?
Levels T5 and L4
Landmarks: L1
Iliac crest
Landmarks: T10
Umbilicus
Landmarks: T8
Lower costal margin
Landmarks: T6
Xiphoid process
Landmarks: T4
Nipple line
Landmarks: C8*
Little finger
*This is important bc there’s a high risk of anesthetizing the diaphragm (C3-5)
What is an advantage to the slower onset of epidurals compared to SABs?
It’s easier to manage vitals
What is the “first sign of hypotension” in SAP/Epidurals?
Nausea=fixing BP will fix nausea
Can sx be performed on a pt with active cardiac dz?
Yes, if they are stable
What is MAC (Monitored Anesthesia Care)?
A type of anesthesia allowing the pt to be sedated and to transition in and out of GA, if that is required by changes in pt or sx conditions
In post-op recovery, how often is BP measured?
Every 5 min for the first 15 min, then every 15 min until d/c
AAOx3 refers to what?
The pt being correctly oriented to time, place, and person
How is post-op hypotension treated?
Fluid bolus or vasopressors
How is post-op HTN treated?
Hydralazine (slow onset=15min) or propranolol (does not incr intracranial pressure)
What is the first line of defense for post-op hypoxemia?
100% O2
What nerve roots make up the Femoral n?
L2-4
What nerve roots make up the Lumbar Plexus?
T12-L4
What nerve roots make up the Sacral Plexus?
L4-S4
What nerve roots make up the Sciatic n?
L4-S3
What is a unique complication of a femoral n block?
Potential for fall 2ry to quadricep weakness