Pharm Unit 2 Flashcards
What can be given for pre-eclampsia?
Magnesium sulfate
What organs are a part of the vessel rich group (VRG)? What % of CO goes to the VRG?
brain, heart, kidney, liver
75%
What is included in the muscle group? What % of CO goes to the muscle group?
skeletal muscle and skin
18%
How much of CO is administered to fat?
5%
What is included in the vessel-poor group? What % of the CO is used?
bone, tendon, cartilage
2%
What are the 5 components of anesthesia?
Hypnosis, analgesia, muscle relaxation, sympatholysis and amnesia
What are the 4 stages of anesthesia?
- Analgesia
- Delerium
- Surgical anesthesia
- Medullary paralysis
What stage of anesthesia includes laryngospasm?
Stage 2 - delirium
What stage of anesthesia includes responses to stimulation that are exaggerated and violent?
Stage 2 - delirium
Which stage of anesthesia includes absence of all reflexes and flaccid paralysis with hypotension and a weak pulse?
Stage 4 - medullary paralysis
What stage of emergence should you extubate in?
Stage 1 - analgesia
What are the 4 protective airway reflexes?
sneezing, coughing, swallowing, gagging
How do barbiturates exert their effect?
Potentiating GABA-a channels, also act on glutamate/adenosine/neuronal nicotinic ACh receptors
What do barbiturates do the CBF/CRMO?
Act as a cerebral vasoconstrictor, reduce CBF and CRMO by about 55%
Why do you want to avoid infusions of barbiturates?
Prolonged context-sensitive half time. They also rapidly redistribute into other tissues - fat and protein reservoir
What is the effect on redistribution if the drug has a high protein binding capacity?
Longer duration of action
How well do barbituates bind to protein? Which protein?
albumin 70-85%
What are the 2 types of barbiturates? Which one is more lipid soluble?
Oxybarbiturates and Thiobarbiturates (more lipid soluble)
Which drugs are Oxybarbiturates and Thiobarbiturates?
Oxybarbiturates: Methohexital, Phenobarbital, Pentobarbital
Thiobarbiturates: Thiopental, Thiamylal
Why is it that: “the greater the ratio of fat to body weightthe less is the blood volume (ml/kg)?” Adipose tissue has….
Decreased blood supply
The greater the ratio of fat to body weight→ the_____ is the blood volume (ml/kg).”
less
__________ describes the distribution of a given agent at equilibrium, between two substances at the same temperature, pressure, and volume
Partition coefficient
__________ describes the distribution of an anesthetic between blood and gas at the same partial pressure
Blood-gas coefficient
A higher blood-gas coefficient correlates with ______ solubility of anesthetic in blood and thus ______ the rate of induction
higher, slowing
Dose of Thiopental?
4 mg/kg IV
Dose of methohexital?
1.5 mg/kg IV
How does methohexital affect seizures?
Lowers seizure threshold = easier to have one, making it an ideal drug for ECTs
Basic effects of barbiturate’s on ventilation?
Dose-dependent depression (less sensitive to CO2) with slower frequency and lower tidal volume, similar to narcotics
What happens during intra-arterial injection of a barbiturate?
Immediate intense vasoconstriction and pain - permanent nerve damage
- Treat with vasodilators: lidocaine or papaverine
What medications are affected by barbiturates? Why?
- Enzyme induction approx. 2 to 7 days of infusion
- Accelerated metabolism of anticoagulants, phenytoin, TCAs, digoxin corticosteroids, bile salts, and vit. K.
- May persist for 30 days
List the induction, conscious sedation and maintenance doses of propofol
Induction = 1.5 - 2.5 mg/kg IV
CS = 25 - 100 mcg/kg/min
Main = 100 - 300 mcg/kg/min
What are the disadvantages to propofol?
- Support bacterial growth.
- Causes increased plasma triglyceride concentrations (in prolonged IV infusions).
- Pain on injection
Describe Ampofol and Aquavan relative to Propofol
Ampofol = low-lipid emulsion with no preservative, higher incidence of pain on injection (good d/t less effect on triglycerides)
Aquavan = prodrug that converts into active form, no pain on injection, by has unpleasant sensation related side effects
Describe Propofol MOA
Selective modulator of GABA-a = increased Cl conductance and hyperpolarized cell
What are the elimination and context-sensitive half-times of propofol?
- Elimination half-time: 0.5-1.5 hours
- Context-sensitive half time: 40 minutes (8 hour infusions)
How does the liver metabolize propofol?
CP450 - converted to water-soluble sulfate and glucuronic acid metabolites to be excreted by kidneys
Describe the BP/HR changes with propofol, etomidate and ketamine
P = decreased BP and HR
E = no change to BP and HR
K = increased BP and HR
T/F: Propofol is safe for alcoholic patients?
T: awakening time does not change with healthy vs ETOH patients
How does the dose of Propofol change with children vs elderly?
Children = increased dose, elderly = decreased dose (by 25-50%)
Why is Propofol advantageous as a sedative?
Prompt recovery, low PONV, anti-convulsant, amnestic, anti-oxidant. Does not provide analgesia however
What is the sub-hypnotic dose of Propofol?
10-15 mg IV followed by 10 mcg/kg/min
Anti-pruritic dose of Propofol?
10 mg IV
What effect does Propofol have on the airway?
Bronchodilation
Anti-convulsant dose of Propofol?
1 mg/kg IV
Effects on CRMO with Propofol?
Decreases CRMO, CBF and ICP. D/t autoregulation, CBF and PaCO2 are maintained
Propofol doesn’t induce seizures but can result in involuntary muscle movements, aka ________
myoclonus
What kind of EEG waves do we want in anesthesia?
Delta
Black box warning for Propofol?
Profound bradycardia leading to asystole in healthy patients
How does propofol work as an anti-emetic agent?
Depresses subcortical pathways and has a direct depressant effect on the vomiting center
Effects of propofol on the CV system
- decreased SBP - SNS inhibition, decreased SVR
- bradycardia
Describe Propofol infusion syndrome including dose
Dose > 75 mcg/kg/min longer than 24 hours.
s/s: severe refractory bradycardia in children, lactic acidosis, brady-dysrhythmias, and Rhabdomyolysis; green urine
What medication can you give with propofol to prevent bradycardia and asystole?
Antimuscarinic agent - atropine
Propofol (does or does not) affect the hypoxic pulmonary vasoconstriction response
does not - stays intact
What does it mean when urine is green or cloudy with propofol administration?
No alteration in renal function/NBD
- green = phenols
- cloudy = uric acid crystallization
Etomidate MOA?
Selective modulator of GABA-a
Dose for Etomidate?
0.2-0.4 mg/kg/ IV
Best indication for etomidate?
In an unstable CV patient
What is the big side effect of etomidate?
Myoclonic movements, very common. Can be prevented with fentanyl 1-2 mcg/kg IV
Contraindication to etomidate?
Adrenal suppression - it makes it worse so you lose your stress response
Relationship of CRMO/CBF to etomidate?
Decrease CBF, CRMO and ICP by 35-45% via cerebral vasoconstriction
Etomidate effects on ventilation?
Is a depressant but less so than barbiturates. Vt decreases are offset by compensatory increases in RR
What is advantageous of ketamine over etomidate/Propofol? Cons?
No pain on injection and profound analgesia at subanesthetic doses. Dose have delirium concerns and abuse potential.
Compare isomers of ketamine
S (the left or -) = more intense analgesia, more rapid recovery, less salivation, lower incidence of emergence reactions
R = (right or +) = cocaine like effect, less fatigue, less cognitive impairment
Where does ketamine work?
NMDA receptors (prevents glutamate from activating them), all opioid receptors (mu, delta and kappa) and weak actions at GABA-a and sigma opioid receptors. Also affects calcium and neuronal nicotinic ACh channels (analgesic effect)
Induction doses IV and IM of ketamine?
IV = 0.5 - 1.5 mg/kg
IM = 4 - 8 mg/kg
Maintenance doses of IV/IM ketamine?
IV = 0.2 - 0.5 mg/kg
IM = 4 - 8 mg/kg
Subanesthetic/analgesic dose of ketamine?
0.2 - 0.5 mg/kg IV
Post op sedation/analgesia dose of ketamine?
1 - 2 mg/kg hour
What anti-sialagogue do you give with ketamine?
Glycopyrrolate
What is the coronary artery disease cocktail (include dosages)?
Valium = 0.5 mg/kg IV
Ketamine = 0.5 mg/kg IV
Ketamine infusion of 15-30 mcg/kg/min
How does ketamine affect ICP? At what dose does the ICP effect plateau?
Potent cerebral vasodilator = 60% increase in CBF, no further increase in ICP at 0.5 - 2 mg/kg IV
Effects of ketamine on the CV system?
Increase in pretty much everything; HR, BP, PAP, CO
Effects of ketamine on ventilation?
No depression of ventilation, airway reflexes are maintained, increase in salivary secretions, bronchodilator
What is the relationship of ketamine to volatiles, NMBDs and Sux?
NMBD = enhanced effect
Sux = prolonged
V = hypotension
Define hyperalgesia and allodynia
Hyper = increased pain sensations to normally painful stimuli
A = perception of pain in response to non-painful stimuli
Where does transduction, transmission, modulation and perception occur in nervous system?
Transduction = signals starting at the nerve endings
Transmission = travel of the electrical impulses to the nerve body connecting to the dorsal horn
Modulation = altering of the signal at the dorsal horn
Perception = discrimination of stimuli in the somatosensory cortex
What is the function of the hypothalamus?
To act as a relay station for incoming pain signals
What medication classes act at peripheral nociceptors or rather affect transduction?
LAs and NSAIDS
What medication classes act on transmission of nerve signals? Where?
LAs and on the a-delta and c-fibers
What medication classes act on modulation and where does this occur?
LAs, opioids, ketamine a2-agonists and in the spinal cord, primarily in the dorsal horn
What medication classes act on perception and where does this occur?
Opioids, a2-agonists, GAs. In the brain -> somatosensory cortex
Describe the process a stimulus would take to travel throughout the CNS
Stimulus -> nociceptor -> exceed resting threshold -> transmission -> modulation -> interpretation/perception
Describe the physiology of c-fibers and type 1 (a-beta) and type 2 (a-delta) fibers including speed
C-fiber = burning pain and sustained pressure pain (2 meters/second)
AB = heat, mechanical and chemical pain
AD = heat
Both alpha = much faster
What are some chemical mediators of pain?
Peptides (substance P, calcitonin, bradykinin, CGRP), eicosanoids, Lipids (PGAs, thromboxane, leukotrienes and endocannabinoids), neutrophins, cytokines, chemokines and extracellular proteases/protons
What are peptide mediators of pain?
Substance P, calcitonin, bradykinin, CGRP
What are lipid mediators of pain?
PGAs, thromboxane, leukotrienes and endocannabinoids
Define primary vs secondary hyperalgesia
P = at the original site of injury, decreased pain threshold, increased response to stimuli, spontaneous pain and expansion of receptive field
SH = uninjured skin surrounding the injury that has been sensitized by central neuronal circuits
Basic function of the dorsal horn
Relay center for nociceptive and other sensory activity
What do the ascending pathways do?
Transmit sensations such as pain to the brainstem and forebrain
What fibers would you find in lamina I?
Afferent C-fibers
What would you find in Lamina II?
The substantia gelatinosa, afferent c-fibers, also where opioids can exert their effect
Where does substance P work?
Lamina III and IV
Where would you find myelinated fibers in the cord? What do they innvervate?
Lamina I, IV, VII and the ventral horn, and they innervate muscles and viscera