p.1
Ventilation-Perfusion Matching
What happens to gas exchange when blood flow is reduced to zero in the lungs?
Gas exchange does not occur, and alveolar concentrations of gases match atmospheric pressure.
p.1
Ventilation-Perfusion Matching
What occurs when ventilation is decreased but blood flow remains constant?
Insufficient gas enters the lungs, leading to poor oxygenation as blood passes through areas of the lung that are not well ventilated.
p.1
Ventilation-Perfusion Matching
What is the normal concentration of oxygen and CO2 in the pulmonary vein?
100 mmHg of oxygen and 40 mmHg of CO2.
p.1
Ventilation-Perfusion Matching
How does body position affect lung ventilation?
Body position changes which parts of the lung are used for ventilation, but typically only about 30% of the lung is utilized at rest.
p.1
Ventilation-Perfusion Matching
What is the relationship between arterial pressure and alveolar pressure in the middle zone of the lung?
In the middle zone, arterial pressure is greater than alveolar pressure, allowing for blood flow and ventilation.
p.1
Ventilation-Perfusion Matching
Why are pulmonary arterial pressures lower than systemic pressures?
Pulmonary arterial pressures are lower, which means there is less force to keep the blood vessels open.
p.3
Ventilation-Perfusion Matching
What is the relationship between ventilation and blood flow in the lungs?
Both ventilation and blood flow are greater in the bottom of the lung than at the top due to gravity.
p.3
Ventilation-Perfusion Matching
Why is ventilation at the bottom of the lung greater than at the top?
Because the alveoli are more compliant, making it easier to get gas in and out.
p.3
Ventilation-Perfusion Matching
How does gravity affect blood flow in the lungs?
Gravity pulls blood down, resulting in greater blood flow to the lower lung regions.
p.1
Ventilation-Perfusion Matching
What is the significance of the ventilation-perfusion (V/Q) ratio in gas exchange?
The V/Q ratio must match to ensure optimal gas exchange; if ventilation exceeds perfusion or vice versa, gas exchange is impaired.
p.9
Gas Diffusion in the Lungs
Why can anesthetics be stored in the fat group?
Because anesthetics are soluble in fat.
p.5
Role of the Lungs in Gas Exchange
Why is immobility important during surgery?
To prevent involuntary movements that could complicate the procedure.
p.5
Role of the Lungs in Gas Exchange
What is Stage 1 of anesthesia characterized by?
Analgesia, amnesia, and euphoria.
What historical significance does dimethyl ether have in anesthesia?
It was one of the first anesthetics used.
p.11
Physiological Importance of CO2 Levels
What is a key characteristic of etomidate?
It has limited effects on the sympathetic nervous system, reducing cardiopulmonary risk.
p.5
Role of the Lungs in Gas Exchange
What significant event in anesthesia occurred in 1846?
The first use of dimethyl ether for tooth extraction.
p.9
Oxygen and Carbon Dioxide Exchange
What does the term 'Tor' refer to in anesthetic distribution?
Tor is the Lambda times the volume capacity divided by the flow rate.
p.9
Partial Pressure of Gases
How do high potency anesthetics affect the lungs?
They are very soluble in blood and brain, leading to rapid exit from the lungs.
p.11
Gas Diffusion in the Lungs
Why are low potency anesthetics like nitrous oxide easier to eliminate?
They can be blown off faster due to lower fat solubility.
p.8
Oxygen and Carbon Dioxide Exchange
What is the volume capacity's role in anesthetic distribution?
It determines how much anesthetic can dissolve into a particular region.
How does increased cardiac output from ketamine affect the patient?
It can put the patient into a negative state faster than other mechanisms.
p.4
Gas Diffusion in the Lungs
What does a straight line on a log plot indicate in terms of gas exchange?
A linear response in the alveoli, indicating effective gas exchange.
p.5
Role of the Lungs in Gas Exchange
What is the significance of different levels of anesthesia for various procedures?
Different procedures require different levels of anesthesia for safety and effectiveness.
p.6
Partial Pressure of Gases
What is the minimal alveolar concentration (MAC)?
The alveolar pressure that abolishes movement response to an incision in 50% of patients.
What are some examples of intravenous anesthetics?
Barbiturates (thiopental), propofol, etomidate, and ketamine.
p.8
Physiological Importance of CO2 Levels
What is the time constant in the context of anesthesia?
The time required for the air equilibration between two areas to reach 63% saturation.
What is a negative effect of ketamine on the cardiovascular system?
It increases cardiac output.
p.9
Ventilation-Perfusion Matching
What is the significance of blood flow in anesthetic distribution?
Only 5.5% of blood flow goes to the fat group, affecting how quickly anesthetics can be stored there.
p.6
Deoxygenated Blood Characteristics
What occurs in the fourth stage of anesthesia?
Medullary depression, where patients no longer breathe on their own and may experience cardiac shutdown.
p.4
Ventilation-Perfusion Matching
What can cause ventilation-perfusion mismatch in patients?
Conditions like lung fibrosis or sickle cell anemia.
p.3
Ventilation-Perfusion Matching
What can happen if too much fluid moves into the lungs?
It can lead to acute mountain sickness.
p.11
Oxygen and Carbon Dioxide Exchange
What is the relationship between anesthetic induction and recovery?
Recovery from anesthesia is quicker if the induction is quicker.
p.8
Gas Diffusion in the Lungs
What does the partition coefficient indicate?
How easily the anesthetic goes into the tissue.
p.5
Role of the Lungs in Gas Exchange
What is the primary goal of anesthesia?
To provide generalized, reversible inhibition of the central nervous system.
How does the functional residual capacity relate to anesthetic delivery?
It represents the volume of tissue divided by the minute ventilation rate, affecting how well anesthetics enter the arteries and alveoli.
p.6
Partial Pressure of Gases
How does isoflurane compare to nitrous oxide in terms of MAC?
Isoflurane has a MAC of 0.00114 atmospheres, while nitrous oxide has a MAC of 1 atmosphere, making isoflurane more potent.
p.8
Gas Diffusion in the Lungs
What happens to the alveolar partial pressure if lung function is good?
It rapidly becomes the same as the arterial partial pressure due to diffusion.
What are the primary benefits of ketamine in anesthesia?
It is very analgesic and very amnesic.
p.6
Physiological Importance of CO2 Levels
What is a common behavior of individuals experiencing agitation and delirium?
They can often be combative.
p.4
Ventilation-Perfusion Matching
What anatomical features can cause a right to left shunt in newborns?
Patent ductus arteriosus and foramen ovale.
p.9
Impact of Air Composition on Breathing
Why is nitrous oxide preferred in dental anesthesia?
Because it acts very quickly to induce anesthesia.
p.11
Gas Diffusion in the Lungs
What happens to high potency anesthetics like methoxyflurane in the body?
They dissolve into fat tissue, making elimination slower.
p.8
Oxygen and Carbon Dioxide Exchange
How is inhaled anesthetic eliminated from the body?
By diffusion out of the tissue into the veins and then into the air space to be breathed out.
p.5
Role of the Lungs in Gas Exchange
What was the initial method of anesthesia before general anesthetics were used?
Chopping off limbs or pulling teeth while possibly getting the patient drunk.
p.3
Ventilation-Perfusion Matching
What is the significance of the pulmonary arteries constricting?
Constriction can increase pressure inside the artery, allowing for blood flow in areas with better ventilation.
p.3
Ventilation-Perfusion Matching
What is the role of the V/Q ratio in lung function?
It helps assess how well ventilation and perfusion are matched in different lung regions.
What is a common method to achieve anesthetic state with high potency anesthetics?
Using a fixed bolus addition of an IV anesthetic.
p.4
Gas Diffusion in the Lungs
What is measured to assess gas exchange efficiency in the lungs?
DLC O (Dead Space) and nitrogen washout.
p.4
Gas Diffusion in the Lungs
What happens to nitrogen concentration in expired air when a person breathes 100% oxygen?
The concentration of nitrogen gradually decreases.
p.5
Role of the Lungs in Gas Exchange
What are the key components of an anesthetic state?
Loss of consciousness, amnesia, immobility, and lack of response to noxious stimuli.
What is the third stage of anesthesia characterized by?
Surgical anesthesia, where patients are in an unconscious state but may still drive their own ventilation.
p.4
Ventilation-Perfusion Matching
What is a shunt in the context of gas exchange?
A condition where blood flow does not adequately participate in gas exchange.
p.4
Ventilation-Perfusion Matching
What happens to oxygen saturation in a baby with a right to left shunt?
Oxygen saturation can drop to 65% or 70% instead of 99%.
p.6
Oxygen and Carbon Dioxide Exchange
How do inhaled anesthetics work?
They are breathed in as gas, diffusing across the lung membrane into the bloodstream to achieve a specific partial pressure in the brain.
p.3
Ventilation-Perfusion Matching
What happens to ventilation and perfusion during exercise?
Ventilation starts to massively exceed ventilation diffusion, particularly in the mid-portion of the lung.
p.5
Role of the Lungs in Gas Exchange
How can alcohol consumption be compared to the stages of anesthesia?
Alcohol can induce similar stages of analgesia and amnesia, particularly in social settings.
p.4
Role of the Lungs in Gas Exchange
What is the primary role of the lungs?
To oxygenate the blood and remove CO2.
p.6
Partial Pressure of Gases
What does a smaller MAC indicate about an anesthetic?
It indicates that the anesthetic is more potent.
p.3
Ventilation-Perfusion Matching
How does the body respond to low oxygen concentration?
By constricting pulmonary arteries to recruit more lung areas for better ventilation-perfusion matching.
What analogy is used to explain anesthetic accumulation?
Filling a bathtub with water while managing the outflow through the drain.
p.6
Gas Diffusion in the Lungs
What is the relationship between inspired partial pressure and alveolar pressure?
They reach an equilibrium state quickly, influencing the concentration of anesthetic in the central nervous system.
What can cause slow induction of the anesthetic state?
Hypoventilation and increased cardiac output can slow the induction.
p.11
Deoxygenated Blood Characteristics
How does chronic obstructive pulmonary disease affect gas exchange?
It reduces gas exchange, leading to a right-to-left shunt.
p.8
Oxygen and Carbon Dioxide Exchange
What factors influence the rate of anesthesia achieved from inhaled anesthetics?
The diffusion rate of the anesthetic, the surface area, the length of the diffusion path, and the partial pressure gradient.
p.8
Partial Pressure of Gases
What is the significance of the partial pressure gradient in anesthesia?
It is the variable that can be changed in inspired air to influence anesthetic delivery.
p.11
Oxygen and Carbon Dioxide Exchange
What is the significance of fat solubility in IV anesthetics?
Fat solubility affects how quickly the anesthetic is metabolized and eliminated.
p.11
Physiological Importance of CO2 Levels
How does propofol function as an anesthetic?
It works on the GABA receptor and is rapidly metabolized.
Which body region receives the least cardiac output?
The vessel-poor region (1.5%).
