Lecture 9 9/12/24 Flashcards
What are the primary goals of the respiratory system?
-provision of adequate gas exchange to allow maintenance of homeostasis
-obtain oxygen from environment for cellular resp.
-eliminate waste products
What is functional residual capacity?
volume left in the lung after a normal tidal breath
What is the function of pre-oxygenation?
fill the functional residual capacity
What causes disturbances in respiratory rhythm?
-pharmacologic effects
-pathophysiology
What is the adverse effect of abnormal respiratory rhythms?
increased respiratory effort
What aspects of the resp. system can be assessed using auscultation or visual assessment?
-resp. rate
-rhythm
-effort
What is ventilation?
movement of gas in and out of the alveoli via inhalation and exhalation
What is the PaCO2 (partial pressure of CO2 in arterial blood) directly proportional to?
VCO2 (amount of CO2 produced)/VA (alveolar ventilation)
What is the gold standard for ventilation evaluation?
PaCO2
What is the gold standard for CO2 monitoring?
arterial blood gas assessment
Why can venous blood be used to estimate PaCO2?
because arterial blood and mixed venous blood have similar PaCO2 levels
What is capnometry?
measure of CO2 in exhaled resp. gases
What are the four phases of the normal capnograph waveform?
-resp. baseline
-expiratory upstroke
-alveolar plateau
-inspiratory downstroke
Where on the capnograph waveform is EtCO2 measured?
at the end of the tidal breath, where the alveolar plateau transitions into the inspiratory downstroke
What is oxygenation?
process by which oxygen diffuses from one location to another
What is the gold standard for evaluation of oxygenation?
PaO2
What is hypoxemia?
abnormally low oxygenation, PaO2 less than 60mmHg
Why can venous blood NOT be used to estimate PaO2?
arterial blood and mixed venous blood have very different levels of PaO2
Why is oxygen saturation used to estimate PaO2?
there is a direct correlation between PaO2 and SaO2 because pressure dictates saturation
Why is a small change in SpO2 important?
a small change in SpO2 is a large change in PaO2 due to the curve relationship
What is the content of arterial oxygen/CaO2?
important determinant of delivery of oxygen that gives a composite of both forms of carried O2 in the blood
What is important about monitoring the mucus membranes?
-want pink, well oxygenated and perfused membranes
-cyanosis requires 5g/dL of deoxygenated hemoglobin
-patients can be hypoxemic and not cyanotic, especially when anemic
What evaluations are important to make when assessing respiratory status?
-RR
-rhythm
-mucus membranes
-SpO2
-capnograph
How does fever differ from hyperthermia?
-fever is an elevation in temperature in order to fight off infection
-hyperthermia results from the inability to dissipate heat
Which region of the brain dictates body temp.?
hypothalamus
Why is temperature maintenance important under anesthesia?
the mechanisms that maintain body temperature have a wider window of activation under anesthesia and do no kick in until the body is much colder than normal
What are the four methods of heat loss that happen in the body?
-convection: moving air removes radiated heat
-evaporation: loss of heat by evaporation of water
-conduction: direct transfer by contact
-radiation: emission of electromagnetic radiation
