Maintenence* Flashcards
what’s included in a “balanced anesthetic?”
IV
Inhalation
Narcotics
Muscle Relaxants
what are two ways to calculate the O2 maintenance requirement?
VO2 = 10*kg^0.75 = ml/min or VO2 = 2.5*kg+67.5 = ml/min
numeric values for dead space
Anatomic Dead space = 2 ml/kg
= 140 ml/B *10 = 1400 ml/min
Alveolar Oxygen Equation
PAO2 = [(PB-PH2O)(FiO2)]-(PaCO2/R)
What is the initial treatment for a patient whose sats begin to drop?
increase FiO2
why does a low BP lead to VQ mismatch?
poor perfusion
PEEP can be simplified to mean what?
resistance to expiration
therapeautic range for PEEP
7.5-10mmHg
What is the physiological value for PEEP?
5 mmHg
advantages of inhalational agents
Rapid appearance of drug in arterial blood Efficient to distribute Easy to deliver - Unique route Predictable recovery High safety profile
drawbacks of inhalational agents?
No analgesia (N20 exception) PONV
MACBAR =
MACawake =
MACamnestic =
MACBAR = 1.5 MACawake = 0.3-0.5 (10% of MAC) MACamnestic = 0.25
what effects do age, accute intoxication and pregnancy have on MAC?
age = increase/decrease EtOH = decrease Pregnancy = decrease
rate of rise for the Fa/Fi curves depends on what?
Solubility
The more _____ the anesthetic agent, the quicker the pt will go to “sleep”
INsoluble
Factors affecting inspiratory concentration (Fi)
Fresh gas flow (increase)
Circuit Volume (decrease)
Any machine/circuit absorption (decrease)
In terms of time constants, what percent must change in order for the change to be therapeautic?
95%
What pathway does the agent take once in the body?
lung -> blood -> brain
Describes relative affinity of anesthetic gas for blood
Blood/gas partition coefficient
Increased partition coeff -> _______ solubility -> ________ agent uptake
increased
increased
Increased agent uptake -> ______ induction
slower
Blood/Gas values for Iso, Des, Sevo
Iso = 1.4 Des = 0.42 Sevo = 0.65
Muscle/Blood values for Iso, Des, Sevo.
& why are they important?
Iso = 4.0
Des = 2.0
Sevo = 3.1
Determines speed of wake up
What is Cardiac Output?
CO = HR x SV
Which agents are most effected by CO?
Highly soluble agents are most effected by CO
What are some factors affecting arterial concentration (Fa)?
V/Q mismatch
Venous admixture
Alveolar dead space
Nonuniform alveolar gas distribution
What effect does N2O have on MAC?
cuts MAC requirement by 50%
N2O advantages
Powerful analgesic properties
Decreases MAC of other inhal. Agents
Safe in MH patients
Rapid induction/recovery
N2O disadvantages
Decreases myocardial contractility
Increase risk PONV
Increase ICP by inc CBF
Teratogenicity
N2O contraindications
Air embolism Pneumothorax (75% 2-3x 10 min) Acute intestinal obstruction Intracranial air (tension pneumocephalus) Pulmonary air cyst Intraoccular air bubbles Tympanic membrane grafting
What does Sevo smell like?
juicy fruit (according to Sam) If you sniff enough, you won't remember it though
What is a potential risk with Sevo and when is it seen?
Compound A (fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether
Low gas flows
High temperatures
Desiccated absorbent
Sevo advantages
Non-irritant sweet odor
Rapid induction/recovery
Does not sensitize myocardium to catecholamine
No CO production with Na lime
Sevo disadvantages
Less potent
Compound A production (2L/min)
Contraindicated with Baralyme
Post op agitation in children*
Which agent is a gas at room temp?
Des
Which gas is Capable of increasing HR, documented myocardial ischemia?
Des
Des advantages
Rapid onset/recovery
Stable with CO2 absorbers
des disadvantages
Requires special vaporizer
Low potency
Pungency (not good for asthma)
Rapid increase >1.25 MAC SNS stimulation
which agent can you not use in pt’s with renal or hepatic dysfunction?
Iso
xenon advantages
Inert Min CV effects Low blood solubility Rapid induction/recovery Nonexplosive Environmentally friendly
xenon disadvantages
High cost
Low potency (MAC – 70%)
Not readily available
Sam’s 10 commandments
- never turn down a break
- You can always give more
- Go ahead it is not my MAMA
- Tank ‘em till they froth, then back off
- Give them what they need add it up later
- Straighten out your lines , keep them that way
- There is always an exception to what you think you know
- Learn how to disagree without being disagreeable
- Never say it has not happened to me
- Never Never use the drugs you give to your patients
Sorry if these cards are confusing
Sam’s slides are hard to work with
