Test 3 Study Guide Flashcards
HCO3 is controlled by this organ
Kidneys
PCO2 is controlled by this organ
Lungs
Hyperventilation levels
PaCO2 < 35 mm Hg
Hypoventilation levels
PaCO2 > 45 mm Hg
Normal PaCO2 levels
35 to 45 mm Hg
Hypercapnia is another term for….
Respiratory Acidosis
Hypocapnia is another term for….
Respiratory Alkalosis
Respiratory Acidosis PACO2 levels
> 45 mm Hg
Respiratory Alkalosis PACO2 levels
< 35 mm Hg
Normal pH levels
7.35 to 7.45
Acidemia levels
< 7.35
Alkalemia levels
> 7.45
any substance that donates a proton [H+] to an aqueous solution (sour taste).
Acid
A [H+] donor is an _____.
Acid
any substance that accepts a proton [H+] , removing it from a solution (bitter taste).
Base
A [H+] acceptor is a _____.
Base
Theory stating that an acid donates protons and a base accepts protons.
Bronsted-Lowry theory
The _____ ______ _____ consists of carbonic acid (H2CO3) and
its conjugate base, HCO3-.
Bicarbonate Buffer System
The bicarbonate buffer system is also known as an _____ buffer system.
Open buffer system
Two places where bicarbonate buffers
In the plasma and In the erythrocyte
The body continually produces _____ ions as a product of ___ metabolism
hydrogen ions, aerobic metabolism
H+ ions formed in the body arise from these three acids
Volatile acids (H2CO3)
carbonic acid (excreted in lungs)
Nonvolatile acids (excreted in kidneys)
____ acids do not have a gaseous component.
Fixed
The _____ buffer system consists mainly of phosphates and
proteins, including hemoglobin
Nonbicarbonate
The nonbicarbonate system is also called the ______ buffer system.
Closed
Most common component in the nonbicarbonate buffer system
Hemoglobin (most important)
The _____ physically remove H+
from the body, and it is dependent on the
blood level of hydrogen ions.
Kidneys
Normal pH values
7.35 - 7.45
Normal PaCO2 levels
35 - 45mm Hg
Normal PaO2 levels
80 - 100 mm Hg
Normal HCO3 levels
22 - 26 mEq/L
Normal BE
± 2 mEq/L
chronic disturbance (non-causative component changed such that pH is in normal range).
Compensated
acute disturbance (non-causative component did not have enough time to
change).
Uncompensated
pH not yet in normal range; non- causative component changed in
appropriate direction but has not had enough time to change sufficiently.
Partly compensated
pH levels at full compensation
7.35 to 7.45
Causes of respiratory acidosis
COPD = most common cause.
* CNS depression.
* Extreme obesity.
* Neuromuscular disease
Hypoventilation causes _____
hypercapnia (respiratory acidosis
Acute hypoxia (due to an exacerbation) ____ alveolar ventilation via hypoxic drive
Increases
Acute reduction in PaCO2
_____ pH
Increases
Compensated respiratory acidosis should not be misinterpreted as ____ _____ _____.
Compensated metabolic alkalosis
Causes of metabolic alkalosis
Vomiting
Nasogastric drainage
Diuretics
NaHCO3 infusion or ingestion
Levels of hypoxemia
Normal: 80-100
Mild hypoxemia: 60-79
Moderate hypoxemia: 40-59
Severe hypoxemia: < 40
Signs and symptoms of hypoxia
50 to 60 mm Hg = mild nausea, lightheadedness, and dizziness and increase in minute ventilation.
35 to 50 mm Hg = mental confusion.
- <35 mm Hg = decreased renal blood flow and cardiac conduction disturbances.
- <25 mm Hg = loss of consciousness and respiratory center depression.
(VA/QC = infinity).
* Normal ventilation but no perfusion.
Absolute dead space
(VA/QC < infinity but > 1)
* Normal ventilation with decreased blood flow.
Relative dead space
; (Right-to-left shunt);
Anatomical shunt
Bronchial systemic veins (carrying deoxygenated blood) emptying directly
into the pulmonary veins (carrying freshly oxygenated blood).
Normal anatomical shunt
Ventricular septal defect: Septum separating the right and left ventricles
has a large hole, allowing deoxygenated right ventricular blood to mix
with oxygenated left ventricular blood.
Abnormal anatomical shunt
- Best known index of oxygen-transfer efficiency.
- A-a gradient = physiological shunting.
P(A-a)O2
: (A-a difference);
Represents the percentage of alveolar PO2
transferred to the arterial
blood.
* More stable than A-a gradient when FIO2
changes.
* Normal a-A ratio = 0.75 - 0.95
* Used to predict FIO2
required to achieve desired PaO
PaO2/PAO2
: (a-A ratio);
Normal P(A-a)O values = 5 to 10 mm Hg
breathing room air
An increase in P(A-a)O2 indicates impaired ___ transfer across the lung
O2
P(A-a)O2 = 30 to 60 mm Hg
Breathing 100% O2
Why is the P(A-a)O2 up when FIO2
is up?
Hb is saturated to capacity when PO2
is between 100 to 663 mm Hg.
(VA/QC = 0)
* Ventilation ceases but perfusion is normal.
Absolute shunt
(VA/QC > 0 but < 1)
* Ventilation is decreased but perfusion is normal.
Relative shunt
However from base to apex, blood flow ____ at a more rapid rate than the
decrease in ventilation.
Decreases
____ regions are over-ventilated with respect to blood flow.
Apical
___ regions are relatively under-ventilated with respect to blood flow.
Basal
As a result, the VA/QC
ratio progressively ____ from the lung base to the lung apex in the upright lung.
Increases
VA/QC mismatch (VA/QC
<1 but >0) is the most common cause of ___
Hypoxemia
- VA /QC mismatch is also called a ____ ___
Relative shunt
- VA /QC mismatch responds well to ____
O2
Average resting alveolar ventilation (VA)
4 L/min
Resting pulmonary capillary blood flow (QC)
5 L/min
Normal ventilation/perfusion ratio (VA /QC) ratio
0.8 for the
lung as a whole.
What is the basic defect of a disease
that causes intrapulmonary
shunting?
Any condition that causes alveoli to become airless creates shunt.
Examples of conditions that cause intrapulmonary shunting
alveolar collapse (atelectasis) and alveolar
filling or consolidating processes (e.g., pneumonia).
