Respiratory, pulmonary and ABG physiology Flashcards
Is the volume in the lungs at the end of passive
expiration
Functional residual capacity (FRC)
Normal FRC
1.7 to 3.5 L
FRC is increased by (3)
1) Body size
2) Age
3) Lung diseases (asthma & COPD)
FRC is decreased by (5)
1) Sex (decreased in females)
2) Paralyzed diaphragms
3) Posture (greatest standing, lowest supine)
4) Lung disease with less elastic recoil
5) Inc abdominal pressure
At low flow, or laminar flow (nonobstructed breathing), The _____ is the major property of the gas that affects flow.
Clearly the major determining factor is the ____ of the
tube.
Viscosity
Radius
At higher flow rate (in obstructed airways and heavy breathing), turbulent flow, the major determinants of resistance to flow are the ______ and _____.
Density of the gas
Radius of the tube
What equation describes the relationship between pressure, FLUIDIC resistance and flow rate?
Hagen–Poiseuille
This law essentially states that the TENSION within the wall of a sphere filled to a particular pressure depends on the thickness of the sphere.
Laplace’s law
normal A-a gradient is estimated as follows:
A-a gradient = (age/4) + 4
Under general anesthesia FRC is reduced by approximately ____ ml in an adult.
The supine position decreases FRC another ___ ml
400 mL
800 mL
Is the sum of anatomic and alveolar dead space.
Physiologic dead space
Is the space is the volume of lung that does not exchange gas.
Anatomic dead space
Examples of anatomic dead space (4)
1) nose
2) pharynx
3) trachea
4) bronchi
How much is the anatomic dead space (mL/kg)?
2 mL/kg
This space is the volume of gas that reaches the alveoli but does not take part in gas exchange because the alveoli are not perfused.
Alveolar dead space
What is defined as blood that reaches the arterial system without passing through ventilated regions of the lung?
Absolute shunt
How many percent of cardiac output is normally shunted through postpulmonary shunts?
2% to 5%
Examples of postpulmonary shunts?
1) thebesian
2) bronchial
3) mediastinal
4) pleural veins
Is a local response of pulmonary arterial smooth muscle that decreases blood flow in the presence of low alveolar oxygen pressure?
Hypoxic pulmonary vasoconstriction (HPV)
What inhibits HPV?
HPV is inhibited by volatile anesthetics and vasodilators but is not affected by intravenous anesthesia.
What is the O2 content per gram hemoglobin?
1.34
CO2 exists in three forms in blood (3)
1) Dissolved CO2 (7%)
2) Bicarbonate ions (HCO3) (70%)
3) Combined with hemoglobin (23%)
What respiratory center is mainly responsible for inspiration?
Dorsal respiratory center
What respiratory center is responsible for both expiration and inspiration?
Ventral respiratory center
What respiratory center helps control the breathing rate and pattern?
Pneumotaxic center
Where is the dorsal respiratory center located?
It is located within the nucleus solitarius where vagal and glossopharyngeal nerve fibers terminate.
Most common iatrogenic cause of hypercarbia?
NaHCO3 administration
Elevated anion gap metabolic acidosis is caused by accumulation of unmeasured anions. What are the causes of elevated anion gap? (4)
1) Lactic acid
2) Ketones
3) Toxins (ethanol, methanol, salicylates, ethylene glycol, propylene glycol)
4) Uremia
What buffer is the fastest to respond to pH change but has less total capacity than the intracelluar systems, this accounts for 60-70% of chemical buffers?
Extracellular bicarbonate system
Primary organ involved in rapid acid-base regulation
Lungs
What organs play a major role in acid-base balance?
1) Lungs
2) Kidneys
3) Liver
4) GIT
Severe acidemia is defined as blood pH of?
< 7.20
Is the amount of base (or acid) needed to titrate a serum pH back to normal at 37 C while the PaCO2 is held constant at 40 mm Hg.
Base deficit (or base excess)
Estimates the presence of unmeasured anions.
Anion gap (AG)
Normal value of anion gap?
12 mEq/L +- 4 mEq/L
What metabolic acidosis results from loss of Na and K or accumulation of Cl. Theresult of these processes is a decrease in HCO3?
Nonanion gap metabolic acidosis
(Nonelevated) Nonanion gap metabolic acidosis causes (5)
1) Iatrogenic administration of hyperchloremic solutions (hyperchloremic metabolic acidosis)
(excess administration of normal saline)
2) Alkaline gastrointestinal losses
3) Renal tubular acidosis
4) Ureteric diversion through ileal conduit
5) Endocrine abnormalities
Elevated AG metabolic acidosis causes (3)
1) lactic acid or ketones
2) poisoning from toxins (e.g., ethanol, methanol, salicylatesethylene glycol, propylene glycol)
3) uremia
