Inhalation Anesthesia Part 2 - Quiz 5 Flashcards
What are the 4 Phases of Uptake & Distribution?
- Inspired Anesthetic Concentraiton
- Alveolar Anesthetic Concentration
- Blood Anesthetic Concentration
- Anesthetic from Blood to Tissue
What is “Wash In”?
Using high flows of O2 or O2/N2O @ 5-10L/min to control partial pressure of Anesthetic Gas
What is the Concentration Effect of Anesthetic Gas?
High Concentrations = Greater Uptake = Greater Inspired Volume
What factors effect the Rate of Alveolar Partial Pressure of Anesthetic?
Inspired Concentration
&
Alveolar Ventilation
When Alveolar ventilation is high, the partial pressure of the anesthetic at the alveolar ______ rapidly.
When Alveolar ventilation is high, the partial pressure of the anesthetic at the alveolar Increases rapidly.
What is the Second Gas Effect?
First gas (N2O) rapidly goes into blood and pulls the second gas (Sevo) along with it –>
causes rise of second gas more quickly
What factors determine how quickly Anesthetics go from Alveoli to Blood?
Solubilty of Gas
Cardiac Output - Rate of blood flow
Partial Pressure of Gases in Arterial/Venous blood
What is the Blood:Gas Partition Coefficient?
Ratio of Anesthetic Concentration in Blood to Anesthetic Concentration in Alveoli
Pa / PA
The more blood soluble the agent, the _____ time required for induction.
The more soluble the agent, the more time required for induction
(Slower Induction)
How does a higher blood flow affect gas delivery to the tissues?
Higher blood flow = more blood exposed to agent = faster pickup of agent
What factors contribute to the teh Partial Presure of Anesthetic in the Tissue?
Solubility of Gas & Tissue Blood Flow
What happens in Stage 1 of Anesthesia?
Stage of Analgesia
Decrease Dorsal Horn Activity & Synaptic Transmission
Duration: Anesthesia Administration to Loss of Consciousness
What happens in Stage 2 of Anesthesia
Stage of Delirium/Excitement
Block of Inhibitory Neurons = Enhance Synaptic Transmission
↑Muscle Tone
Irregular Breathing
Dilated Pupils
↑BP & ↑HR
Begins: Loss of Consciousness
What happens in Stage 3 of Anesthesia?
Stage of Anesthesia
Depression of Ascending Sensory Pathways
Supression of Spinal/Skeletal Activity
Regular Breathing
Centered Pupils
Absent Cough, Gag & Eyelid Reflex
What happens in Stage 4 of Anesthesia?
Stage of Depression
Depression of Medullary Centers
Profound Respiratory & Cardiac Depression
The lower the MAC, the ____ potent the agent and the ______ the blood:gas partition coefficent.
The lower the MAC, the more potent the agent and the higher the blood:gass partition coefficent
What are Factors that Decrease MAC?
Hypoxia
Anemia
Hypotension
Other Drugs
Pregnancy
Elderly
What are Factors that Increase MAC?
Infants
Hyperthermia
Chronic Drug/Alcohol Use
How does Hyperthermia > 42 C affect MAC?
Decreases MAC
How does Anemia w/ HCT < 10% affect MAC?
Decreases MAC
How does a PaO2 > 95 mmHg d/t decrease in pH in the CSF affect MAC?
Decreases MAC
How does Hypo/Hyperthyroid affect MAC?
No effect
How does Hypercalcemia & Hyponatremia affect MAC?
Decreases MAC
How does Hypernatremia affect MAC?
Increases MAC
What drugs increase MAC?
Cocaine, Ephedrine & Acute use of Amphetamine
At what MAC will 95% of patients not move?
1.2 MAC
99% @ 1.3 MAC
What is MAC-awake?
50% of patients will respond to “Open your eyes”
0.3 MAC = Loss of Recall
What is MAC-BAR?
MAC needed to block Adrenergic Response to Skin Incision
What is MAC intubation?
Same as MAC-BAR - more gas than that needed for surgical incision
What is one thing that restricts the application of using MAC as a guideline?
Frequency of Muscle Relaxant Administration
Factors that are invovled with getting Gas from Machine to Lungs
Inspired Partial Pressure
Alveolar Ventilation
Breathing System Properties
Factors involved in getting Gas from Lungs to Blood
Solubility of Gas to Blood
Cardiac Output
Alveolar to Venous Pressure Difference
Factors involved in getting Gas from Blood to Brain?
Brain:Blood Partition Coefficient
Cerebral Blood Flow
Arterial to Venous Partial Pressure Difference
What is the MAC% for Desflurane?
6%
What is the MAC% for Sevoflurane?
2%
What is the MAC% for Isoflurane?
1.4%
What is the λoil:gas for N2O?
1.4
What is the λoil:gas for Desflurane?
19
What is the λoil:gas for Sevoflurane?
51
What is the λoil:gas for Isoflurane?
98
What is the λblood:gas for N2O?
0.47
What is the λblood:gas for Desflurane?
0.45
Wht is the λblood:gas for Sevoflurane?
0.65
What is the λblood:gas for Isoflurane?
1.4
How does High Cardiac Output effect Gas buildup in the Alveoli?
High Cardiac Output slows gas buildup in the alveoli & induction because blood take up the gas too quickly
How does Low Cardiac Output effect Gas buildup in the Alveoli?
Gas builds up faster in the alveoli because of less uptake by blood
How does at Right-to-Left Cardiac Shunt effect induction?
Slows Induction d/t dilution of blood w/o any anesthetic
How does Left-to-Right Cardiac Shunt effect Induction?
No Effect
What is Diffusion Hypoxia?
When N2O is stopped abruptly and the patient is only breathing Room Air.
The N2O in the body is still diffusing into the Alveoli –> give 100% O2 for 5-10 min
What factors influence Rate of Emergence?
Duration of Procedure
Temperature of Patient
Patient’s Physical Condition
Obesity
What is the Difference between Emergence and Induction?
No Concentration Effect
Tissue serves as Reservoir, Not Blood
Metabolism
What does the Elimination of Anesthetic Gas depend on?
Length of Administration
Solubility of Gas in Blood & Tissues
