Respiratory System Flashcards
What is the definition of hypoxemia?
A PaO2 of less than 80 mmHg (decreased oxygen content in the blood)
Defined as: when metabolic demand EXCEEDS oxygen delivery
What constitutes severe hypoxemia?
A PaO2 of 60 mmHg or less (decreased oxygen content in the blood)
Defined as: when metabolic demand EXCEEDS oxygen delivery
The atmosphere is made up of what percentage of oxygen?
21%
The atmosphere is made up of what percentage of nitrogen?
78%
The volume of gas normally inspired with a given breath is known as what?
Tidal volume (Vt)
What is a patients appropriate tidal volume?
Between 10-20mL/kg (slightly less with a cat)
What does the following equation represent?
Ve = Vt x Vf
Minute volume (total ventilation) equals the patients tidal volume times their frequency (rate of breathing)
What diseases can be associated with dull or absent lung sounds?
Pleural space disease; severe lung consolidation of lung parenchyma, pleural effusion, pneumothorax
What are possible causes of increased breath sounds, wheezes or crackles?
Pulmonary parenchymal diseases: aspiration pneumonia, ALI, ARDS, fluid overload, congestive heart failure, and pulmonary thromboembolism.
Parenchyma is made up of alveoli, interstitial tissue and fibers and is involved in gas exchange.
Risks factors for the development of ALI or ARDS include:
SIRS, sepsis, infection, smoke inhalation, near drowning, severe trauma.
What percentage on an SpO2 constitutes hypoxemia?
An SpO2 of less than 95% or a partial pressure of oxygen (PaO2) of less than 80 mm Hg
Acute lung injury or ARDS can be identified using what formula?
PaO2 to FiO2 ratio (P/F ratio)
*controlled oxygen?
ALI may be suspected in patients with a PaO2 to FiO2 ratio of what?
< 300
ARDS may be suspected in patients with a PaO2 to FiO2 ratio of what?
< 200
How is a shock index calculated?
Heart rate divided by blood pressure
What shock index result can identify shock in both dogs and cats?
Shock index of > 1 in dogs and > 1.6 in cats.
What is the normal inspiration to expiration ratio?
1:2 meaning a patient exhales twice as long as it inhales in normal breathing
Increased inspiration time can be an indication of what?
Upper airway obstruction or extrathoracic pathology
Increased expiration time can be an indication of what?
Lung pathology like pneumonia or intrathoracic pathology
What type of breathing is associated with the chest and abdomen moving together?
Synchronous breathing
What type of breathing is associated with the chest and abdomen moving opposite of one another?
Asynchronous breathing
Asynchronous breathing is often a sign of pathology located where?
In the pleural space
Synchronous breathing is often a sign of pathology located where?
Inside the lungs
Define restrictive breathing patterns and when you might see it.
Short and shallow breaths indicating pleural space disease
Poor excursions
Define Kussmaul breathing and when you might see it.
Rapid and very deep breathing pattern. May see this in diseases causing severe metabolic acidosis like DKA or renal disease.
Define stridor
A high pitched sound produced by turbulent airflow through the UPPER airway (partial airway obstruction).
Define stertor
Abnormal low pitched sound produced lower in the airway (partial airway obstruction)
How much hemoglobin is required in the body to show physical signs of cyanosis?
5g/dL
What is the oxygen flow rate range for nasal cannulas?
50-150mL/kg/min
Under normal circumstances, a patient that has an EtCO2 of 40 mmHg is expected to have a PaCO2 of approximately:
42-47 mmHg.
EtCO2 will be 2-5 mmHg less than PaCO2.
What are common causes of HYPOcapnia?
Hyperventilation, decreased cardiac output and carbon dioxide production, and metabolic acidemia resulting in respiratory alkalosis.
What are causes of HYPERcapnia?
Hypoventilation, rebreathing of carbon dioxide, or increased carbon dioxide production.
What are consequences of HYPERcapnia?
Systemic vasodilation, increased cardiac output, increased heart rate, increased blood pressure, respiratory acidemia, metabolic alkalosis, electrolyte changes, neurological dysfunction, cerebral vasodilation, increased cerebral blood flow and increased intracranial pressure, narcosis and death.
What are consequences of HYPOcapnia?
Vasoconstriction of cerebral blood vessels resulting in decreased intracranial pressure (can be positive). If too low, can also compromise cerebral blood flow and cerebral oxygen delivery.
What is the name of the acupuncture point that’s attempting to be stimulated to encourage respiration called?
Governing Vessel 26 (GV 26) located between the nares at the top of the nasal philtrum.
Expired carbon dioxide is directly proportional to what?
Pulmonary blood flow.
Capnograph: Ideal monitor for measuring effectiveness of chest compressions during CPR.
List 3 major things ETCO2 can determine.
- Rate of tissue perfusion
- Cardiovascular - rate of exchange from blood to alveoli
- Ventilation - rate of removal by alveolar ventilation
^provides information on metabolism, circulation and ventilation
What are 5 types of HYPOXIA
- Hypoxemic hypoxia: inadequate oxygen-carrying capacity if blood (CaO2)
- Hypemic hypoxemia: “anemic hypoxia” occurring when anemia causes a decrease in circulating hemoglobin
- Stagnant or circulatory hypoxia caused by decreased cardiac output and poor perfusion
- Histiotoxic hypoxia resulting when tissues are unable to extract and utilize oxygen
- Metabolic hypoxia when the is an increased cellular consumption of oxygen (VO2)
What is the definition of HYPOXIA
When there is inadequate oxygen delivery (DO2) to meet tissue metabolic demand (VO2) causes by inadequate tissue perfusion, metabolic disturbances, or lack of oxygen supply.
What are the 5 causes of HYPOXEMIA
- Decreased FiO2
- Hypoventilation
- Ventilation/perfusion (V/Q) mismatch
- Diffusion impairment
- Right to left shunt
During the Bohr effect, or states with increased CO2, lower pH and increased temperatures, the oxygen-hemoglobin dissociation curve will shift in what direction? What does that mean?
There will be a shift to the right, meaning oxygen has less affinity with hemoglobin and more oxygen becomes unbound for delivery to tissue.
*Think higher CO2, need more O2.
During the Haldane effect, or states with decreased CO2, higher pH and decreased temperatures, the oxygen-hemoglobin dissociation curve will shift in what direction? What does that mean?
The curve shifts to the left resulting in oxygen being more tightly bound to hemoglobin and less oxygen offloading.
*Think less CO2 means the need for less oxygen.
What is the carbonic anhydrase reaction formula?
CO2 + H2O <—> H2CO3 <—> HCO3- + H+
This is why pH is directly affected by the ratio of CO2 and HCO3-
*CO2 is a major bi-product of internal cellular respiration and has a significant role in maintaining acid base status, and is not just a waste product.
What are the 4 phases that a breath can be broken down into?
- Initiation of inspiration
- Inspiration
- Termination of inspiration
- Expiration
