General
Fraction delivered (FD) - Fraction inspired (Fi)
Alveolar ventilation & anesthesia delivery system characteristics
How do you calculate MAC?
150 / oil:gas partition coefficient
What two medications do not produce coronary artery vasodilation?
Desflurane and Sevoflurane
Which medication is the worst for inhalation induction and why?
Desflurane is an airway irritant
Will cause increase secretions & coughing, bronchospasm, laryngospasm, and breath-holding
4 Factors that contribute to CO formation
Dryness of CO2
Increase temperature of CO2 absorbers during low gas flow rates
Increased prolonged fresh gas flow rates that cause desiccation of CO2 absorbent
Type of CO2 absorber Baralyme > Soda Lime
How does BGSC affect PA/PI?
Low BGSC = fast increase of PA toward PI b/c gas doesn't want to leave the alveoli
Whats the max dose of epinephrine you can give to a patient on enflurane?
10.9 mcg/kg
More than this dose will cause ventricular cardiac dysrhythmias
Right to left shunts causes what to induction?
Decreases Pa by dilution and slows induction
Left to right shunts increases the Pa and speeds induction
Hyperventilating with enflurane would do what?
Increase seizure risk, metabolic demand (CMRO2), CBF, and ICP
Opposite with other VA
Factors that increase MAC (6)
HyperNa, hyperthermia,
Increased NT levels, increased CNS catecholamine activity,
Alcohol abuse
If your patient has a Hct of 21%, what can you anticipate for your inhaled anesthetics?
A decreased BGPC = Faster onset
"BGPC are 20% less with HCT of 21% vs. 43%"
Ratio of increase PI would do what to PA?
4 fold increase in PI would increase PA by 6 fold
List the impact that VA have on evoked potentials from most to least sensitive
Visual evoked potential > Somatosensory Evoked Potential > Brain Stem Auditory Evoked potentials
Order of VA agents that causes Malignant Hyperthermia (MH)
Halothane > Enflurane > Isoflurane > Desflurane/Sevoflurane > N2O
5 Signs of fluroide-induced nephrotoxicity
Polyuria, hypernatremia, hyperosmolarity, increase Cr, inability to concentrate urine
In order, which agents react with soda lime to produce a harmful chemical? What is that chemical?
Des > Enflurane > Isoflurane (DEI)
Produces CO
Your patient is on 70% N2O & 30% O2. What MAC of Sevoflurane is needed to prevent HR changes during surgery?
The MAC values of Sevoflurane at 70% N2O and 30% O2 = 0.69%
MAC(BAR) is 1.5x MAC so 1.035
Describe ischemic pre-conditioning with VA
VA release adenosine -> increase protein kinase C activity -> less K+ channel inhibition by ATP -> increase K+ channel activity -> less Ca accumulation -> shorter cardiac action potential -> mild negative inotropic action
-PROTECTIVE AGAINST ISCHEMIC OR HYPOXIC INSULT
-30 min of 1 MAC prior to ischemia has been shown to decrease infarct area
N2O at anesthetic dose: N2O > 70% causes what?
Increases CO d/t sympathomimetic effects
Increases HR, BP, muscle blood flow
Decreases SVR
Factors that decrease MAC requirements (12) sorry..
Increase age
Metabolic acidosis
Hypoxia, hypotension, hypothermia, hyponatremia, hypo-osmolality
Decrease NT levels
Pregnancy
Meds: Alpha-2 agonist, lithium, acute ethanol intoxication
VA anesthetics affects on:
Na+ channel
Ca2+ channels
K+ channels
and what happens with each?
Na: Inhibited; decreased release of NT causing amnesia, unconsciousness, sedation, & immobility
Ca: Inhibited; high doses of VA can -> decrease contractility (- inotropic)
K+: Potentiated; hyperpolarization -> less NT release
MAC values for 100% O2 for all drugs
Halothane: 0.75%
Isoflurane: 1.17%
Enflurane: 1.63%
Sevoflurane: 1.8%
Desflurane: 6.6%
What affects FA?
Uptake, Ventilation, Concentration, Second Gas Effect
What medication can prolong QTc interval?
Halothane, Enflurane, Isoflurane, Sevoflurane
Unconsciousness is caused by VA influence on... (3)
Amnesia is caused by VA influence on... (4)
Immobility is caused by VA influence on... (2)
-Amnesia: Hippocampus, Amygala, Medial-Temporal Lobe, Cortical areas
-Immobility: Spinal & Supraspinal