Anesthesia - Total Flashcards
NAme the different forms of anesthesia and the drugs used for them.
IV = Propofol, Ketamine, Etomidate, Dexmedetomidine etc
Inhaled Anesthetics: Isoflurane, Desflurane, SEvoflurane, Nitrous
Sedatives: Midazolam and Diazepam
Narcotics/Opioids: Morpine, Fentanyl etc
Local Anesthetics: Lidocaine and Bupicavaine
Muscle Relaxants: Succinylcholine or Rocuronium
Others: Antiemetics, Anticholinergics, Reversal agents
Name the 4 IV Anesthetic agents (non-barbituate or benzodiazepine).
Of those, which ones cause Respiratory Depression and need skilled airway technicians and which ones can be given outside of OR (like ER/ICU)?
Which ones cause bronchodilation? (therefore good for asthmatics and smokers)
Names: Propofol, Ketamine, Etomidate, and Dexmedetomidine
Propofol can cause POTENT respiratory depression/apnea and also suppresses upper airway reflexes and so is good for Bronchoscopy/Upper Endocopy procedures and instrumentation of the airway and causes Bronchodilation
vs
Ketamine*, Etomidate*, and Dexmedetomidine cause minimal respiratory depression (*if infused slowly); Ketamine and Demedotmidine good for ER/ICU
Ketamine causes Bronchodilation (good for asthmatics) but also increased secretions so give with **Glycopyrrolate **
Name the 4 IV Anesthetic agents (non-barbituate or benzodiazepine).
Of those, which ones cause Cardiovascular depression/instability?
Names: Propofol, Ketamine, Etomidate, and Dexmedetomidine
ETOMIDATE = good for CV stability!!! Use for Trauma and Cardiac patients
vs
Propofol causes vasodilation and hypotension
Ketamine causes Increased Sympathetic tone - Increased HR, BP, CO and Myocardial Oxygen use - **DO NOT USE WITH CAD or cardiac patients **
Dexmedeotimidine causes CV depression, bradycardia and hypotension - **DO NOT USE with CV pts or in Kids where CO depends on HR **
Name the 4 IV Anesthetic agents (non-barbituate or benzodiazepine).
Of those, which ones are good for Neurosurgery/brain patients? Which ones cause CNS effects and what are those effects?
Names: Propofol, Ketamine, Etomidate, and Dexmedetomidine
Propofol decreases CBF, CMRO2, ICP, is anti-convulsant and neuroprotective = IDEAL for neurosurgery patients with TBI, Tumor or seizure
vs
Ketamine - Increase CBF, CMRO2 and causes siezuers - DO NOT USE in TBI/neurosurg
Etomidate - decrease CBF and CMRO2 but causes Myoclonus/Seizuers in 50% pts
vs
Dexmedetomidine - sedation and analgesia with no real changes in CMRO2 or ICP
Name the 4 IV Anestetic agents (non-barbituate or benzo) and their mechanism of action.
Which ones have analgesic effects?
Propofol and Etomidate = Potentiates the opening GABA Type A receptor Chloride channel to decrease AP propogation in Post-synaptic neuron
Ketamine = NMDA receptor antagonist (stops binding of Glycine and Glutamine which are excitatory) to decrease POst-synaptic AP firing AND causes increased catecholamine release
Dexmedetomidine = A_lpha2 Adrenergic Receptor Agonist_ that acts in Locus Ceruleus to decrease NE release and firing in SC and Brain
Ketamine and Dexmedetomidine have analgesic effects!
Propofol - uses, metabolism and effects.
Warning?
Pros and Cons
- Made with soybean, glycerol and lechicin -<strong> EGG ALLERGY!</strong>!! and Needs sterile technique
- Metab in Liver and excreted via Kidney but pts wake up in 8-10 after bolus from **Redistribution **
- used for induction, maintenance, and sedation (repeat boluse for dental procedure)
- good for Tumor/TBI/Seizure neurosurg patients and for bronchoscopy/endoscopy bc stops Airway reflexes
EFFECTS: Neuroprotective, CV depression (hypotension), Resp depression but with bronchodilation, Anti-emetic
WARNING: PIS = lactic acidosis with long term infusion -do not use in ICU
Pros: amnesia, fast on/off, ant-emetic, neuroprotective, bronchodilation
Cons: Pain with injection, no pain relief, cardiac and respiratory depression, Egg allergy, PIS
Ketamine - uses, metabolism, effects
Warning?
Pros and Cons
- Used for induction (can be IM), maintenance, Sedation (for short pain procedures like burn dressing changes), and post-op pain (abdominal, thoracic, ortho) and chronic pain - _Sedative/Dissociative and Analgesic _
- Metab to Nor-ketamine (less active metab) in Liver and excreted ~3 hours
- CAN INCREASE CATECHOLAMINES - vasoconstriction and bronchodilation
Given with Midazolam for Emergence Reaction and Glycopyrrolate for Secretions
NOT for Neurosurgery pts or pts with CAD or CV patients. Good for asthmatics.
- Effects: Dissociative, can cause seizures, Emergence reaction/hallucinations, increased Sympathetic tone and Myocardial depression in critically ill pts
PROS: Analgesia (good for chronic pain and narcs), MINIMAL Resp depression, can be given IV/IM/Rectal/Oral/Epid, Bronchodilation
CONS: Emergence delerium (combat with Midazolam), Increased resp secretions (combat with Glycopyrrolate), HTN + Tachycardia and then cardiac depressio in ill pts, Increased ICP and Seizures (not for TBI pts)
Etomidate - uses, metabolism, effects
Warnings?
Pros and Cons
- used for Anesth Induction in Unstable CV patients
- Metab by Ester Hydrolysis; peak to brain in 1 minute - fast but then into urine/bile in 2-5 hrs
WARNING: ADRENOCROTICO SUPPRESSION with just 1 dose: blocks 11beta hydroxylase from converting cholesterol to cortisol and so really sick ICU pts can’t have life-saving stress response afterwards
Effects: CV stability, minimal resp depression, Decreased CBF and CMRO2 but causes Myoclonus in 50% pts
PROS: CV stability and minimal resp depsession
CONS: Pain on injection, Seizures!!!, Adrenocorticosuppression - not for ICU PTS!!!, Myoclonus (rigity and so have to time correctly with muscle relaxants for intubation)
Dexmedetomidine - uses, metab, effects
Warnings?
Pros and Cons
- used for sedation for procedures and as general anesthesia bc decreses doses for inhaled and analgesics
SOME ANALGESIA
Effects: CNS sedation and analgesia but no changes in ICP etc, CV depression (hypotension and bradycardia - NOT used for CV pts or Kids), Minimal Resp depression
Pros: sedation and analgesia, no respiratory depression
Cons: hypotension, bradycardia, Longer onset and Duration
What are the Benzodiazepines? How are they used? Metabolised? Mechanism? Effects?
Midazolam and Diazepam both bind to specific sites on GABA receptor and increase affinity of receptor for GABA leading to increased hyperpolarization of post-syn neuron and decreased AP firing
Metab - in liver and Midaz to inactive metabolite and Diazepam to 2 active metabolites which is why it causes the Hangover Effect and has longer half-life
- They have rapid onset into BBB and are off with Redistribution
- Midaz can be taken lots of ways but diazepam is only oral
Used for Pre-Op anxiety or Amnesia, Sedation in short procedures, and seizure suppression
Effects: CNS - sedation, hypnosis, Amnesia, antoconvulsant, decreased CMRO2 and blood flow; Resp - minimal resp depression; CV - lowers TPR and BP (midazolam more) but no real changes in CO
What are the BArbituates? Special Features? Metabolism? Effects? Uses?
Warning!
Thiopental and Methoheital are salts that mix with water to make Alkaline pH solutions (pH>10) and bind to GABA A receptors and increase affinity for GABA.
Metabolized in Liver and have INDUCTION effects and are cleared more rapidly with inducers (ex. takes longer to put down an Alcoholic with Thiopental)
- Precipitates with Acid in IV lines
Used for Induction and neuroprotection for putting pts in coma with increased ICP or Focal Ischemia
Effects: CNS - sedation, anesthesia, *DECREASE Pain threshold!!!, decrease CBF, ICP, CMRO2 (can cause coma/flatline); CV - decrease BP and vasodilation thats exagerated in elderly, CV disease, and hypovolemia pts; Resp - decrease minute ventilation, Tidal volume, RR, and responses to hypercapnea/hypoxia but no suppression in airway reflexes; PAIN on injection and GANGRENE if injected into arteries (can lose hand/feet)
WARNING: DO NOT USE IN ACUTE INTERMITTENT PORPHYRIA
- stimulate D-ALAS synthesis of Heme and pts with AIP can’t convert the final step of Porphyrinobilinogen to Heme and so it builds up and get hallucinations, psychosis, numbness, abdominal pain etc
What is the common moiety for all of the volatile anasthetics?
Ether
What are the general effects of Inhaled Volatile Anesthetics? what do they all cause?
Unconsciousness, Amnesia, Immobility
BRONCHODILATION!
Vasodilation and hypotensoion that’s particularly bad in sick patients who can’t recover from it
What is MAC? Significance? Use?
MAC = concentration of anesthetic to stop movement in 50% of patients
GOAL = MAC 1
At MAC .5 Amnesia
At MAC 1.2 or 1.3 can get dangerous (CV failure and coma)
**IN GENERAL: Increase MAC then Decrease Potency and MACs are additive **
**Measure of Potency essentially **
What is the blood gas partition coefficient and what does it mean?
Measure of solubility of the gas in blood (trends are generally applicable to tissues as well)
Lower Number = Less soluble
N2O < Des < Sev < Iso
Iso is most soluble - therefore takes the longest for emergence
Nitrous and DES are least soluble in all tissues
What are the inhaled anesthetics?
Desflurane, Sevoflurane, Isoflurane, and Nitrous
Desflurane - MAC, solubility effects/uses
Least Soluble (low Blood Gas Partition coeff) therefore good for long surgeries and obese patients bc Rapid on/off
Least potent (High MAC) - have to use ALOT and is VERY expensive!!!
Effects - Tachycardia!!!
Sevoflurane - MAC, solubility, uses and effects
Medium Solubility (BGpartition coeff) so good for long cases and obese people for on/off rapidity
Medium Potency (MAC)
CHEAP!
Non-pungent so no resp secretions or coughing
Effects - **Emergence Delerium, **can Prolong QT Interval
Uses - used in PEDS for induction bc non-pungent and then once IV is placed switched to Iso so no emergence delerium
Isoflurane - MAC, solubility, effects, and uses
MOST soluble (highest coefficient) - therefore longer emergence and so bad for long surgeries and obese people bc long-acting
MOST Potent (Lowest MAC)
Most economical
*HEMODYNAMIC STABILITY
Used alot!
Nitrous - MAC, Uses, Contraindications, effects
Can NEVER achieve a MAC of 1 with it bc then there would be no oxygen in inhaled gas so used in combination with others
Cheap and can cause Second Gas Effect: diffuses faster than nitrogen and so increases air spaces in lungs so can get more of other gases in faster
Cheap
**USED FOR PEDS INDUCTION bc non-pungent **
Effects: - Increased N/V
NOT FOR USE IN SURGERIES WITH AIR SPACES: bowel, distension, lungs - pneumothorax, middle ear
DO NOT USE with Laprascopically
Why is PA measured with inhaled Anesthetics? What are the factors that change PA?
PA = Pa = Pbr and when constant Pbr then constant PA measured
1) Solubility: based on blood gas partition coefficient
- MAIN factor for induction and emergence
- Dont want gas to be very soluble in blood bc want it to go out to act in brain
- N2O < Des < Sevo< Iso
_2) PI - inspired anesthetic partial pressure _
- increased parital pressure then faster induction and then once uptake into blood slows then can decrease PI for maintenance and constant Pbr
3) Alveolar Ventilation: increased ventilation accelerates induction bc faster when breathing more/harder
4) CO: lower CO then increased induction bc more passengers able to get on/off the train
Factors for Emergence from inhaled anesthetics?
Solubility - less soluble then out from tissues/sytem faster (ex. Iso most soluble and longest emergence)
**Alv Ventilaion and CO **
Tissue Concentration - reservoir for gas that determines duration
Metabolism - not clinifcally significant
Organ effects for Inhaled Anesthetics: Cardiovasular
Volatile Anesthetics decrease MAP bc cause Vasodilation (N2O no change MAP)
Changes in HR - Desflurane causes Tachycardia
Few arrhythmias
*Cardioprotective! Ischemic preconditioning
**Sevoflurane - can Prolong QT **
Organ Effects for Inhaled Anesthetics: Respiratory
Incresaes in RR but decreases in Tidal volume = no change in Minute Ventilation but are breathing shallower and faster so get Decrease FRC and Increase Dead Space
Reduced gas exchange = increase PaCO2 and less responsive to it at high MAC = **Apnea **
Sevo and Nitrous = non-pungent so no coughing or secretions
ALL VA CAUSE BRONCHODILATION
Organ Effects for Inhaled Anesthetics: CNS
- Cerebral Vasodilation, Increased CVF and ICP!!!!
*VA cause Uncoupling of CBF and CMRO2!!!! BAD for tumors and bleeding
… but sometimes decrease CMRO2 can be neuroprotective
Dose-dependent CNS depression
N2O has some analgesic effects
Organ Effects for Inhaled Anesthetics: Random other effects
Neuromuscular - VA can cause dose-dependent skeletal muscle relaxation and enhances paralytics
Renal = transient decreases in renal blood flow and GFR
Liver = reduced hetapic flow
