Essential Concepts in Oxygenation Flashcards
What is the process of O2 leaving the alveoli to combine with Hgb or dissolve in blood to be carried to the left side of the heart?
perfusion
What does ventilation depend on (5)?
conducting airways, ventilatory muscles, thorax, elasticity of the lungs, and nervous system/regulators
Where are the sensors (chemoreceptors) responsible for ventilation located?
medulla (central) and aortic arch (peripheral)
What are the chemoreceptors in the medulla sensitive to?
H+ ions (increase in H+ ions increases ventilation)
What are the chemoreceptors in the aortic arch sensitive to?
PaO2 and PaCO2… (decrease in PaO2 increases ventilation, increase in PaCO2 or H+ will increase ventilation)
What is the PaCO2 level for respiratory distress?
greater than or equal to 50
What is the PaO2 for a patient in respiratory distress?
less than or equal to 60
What is the Ph of someone to be considered in respiratory distress?
less than or equal to 7.3
What is the environmental percentage O2 in the air?
21%
What is the type of alveoli that account for 90% of total alveolar surface within the lungs?
type I alveolar epithelial cells
Which type of alveoli produce, store, and secrete pulmonary surfactant?
type II alveolar epithelial cells
What happens in the type I alveoli cells are injured?
they become inflamed
What does surfactant do in the lungs?
lowers the surface tension of the lungs, increases pulmonary compliance, and ease the WOB
What happens if there is a disruption of synthesis/storage of surfactat?
collapse of alveoli which impairs the pulmonary gas exchange
What type of molecule is surfactant?
phospholipid
Which cells play a phagocytic role in alveoli?
monocytes
What is released when microorganisms are being killed by macrophages in the alveoli?
h2o2 (peroxide)
What are the 3 factors that affect gas exchange?
pressure gradient, surface area, thickness
What is the pressure gradient a measure of?
PAO2:PaO2
How much does the A-a gradient increase for every 10% increase in FiO2?
5 to 7 mmHg
What is the proper intervention for increasing the PAO2: PaO2 gradient?
oxygen supplementation
What is the A to a gradient also known as?
driving pressure
What are 4 interventions that increase the surface area in the lungs?
incentive spirometer, TCDB (turning, coughing, and deep breathing), sighs/yawns, positive end expiratory pressure
What is the main cause of decreased surface area in the lungs?
fluid in the lungs
The thicker the alveolar capillary membrane, the ______ the rate of diffusion
slower
What are conditions that increase alveolar capillary membrane thickness?
ARDS, Pulmonary edema, Pulmonary Fibrosis, and Heart Failure
More than 97% of all oxygen is transported in this form
oxyhemoglobin
What is oxygen saturation measured as?
SaO2 and SpO2
What percentage of oxygen is transported in the dissolved blood?
3%
How is PaO2 measured?
ABG
What is the normal pH?
7.35-7.45
What is the normal PaCO2?
35-45
What is the normal PaO2?
80-100
What is the normal SaO2?
95-100%
What is the normal HCO3-?
21-28
What are 5 common causes of respiratory acidosis?
COPD, pneumonia, atelectasis, neuromuscular disease, post-op recovery, narcotics
What are 5 common reasons for metabolic acidosis?
diabetic acidosis, starvation, impending shock, ASA OD, diarrhea
What are 6 common causes of respiratory alkalosis?
hysteria, fear, anxiety, head injury, pain, fever, ventilator
What are 4 common causes of metabolic alkalosis?
diuretics, prolonged NG suction without electrolyte replacement, excessive vomiting, overuse of antacids
What causes respiratory alkalosis?
low PCO2 due to hyperventilation (excess amount of CO2 exhaled)
What causes respiratory acidosis?
excessive retention of CO2 due to hypoventilation, leading to a decrease in pH below 7.35
Why does diarrhea cause metabolic acidosis?
loss of HCO3-
With a high temperature, does the oxyhaemoglobin dissociation curve shift to the right or left?
right
With a low temperature, does the oxyhaemoglobin dissociation curve shift to the right or left?
left
What is the normal alveolar ventilation?
4L/min
What is the normal pulmonary capillary perfusion?
5L/min
What is the normal V/Q ratio?
4:5 or .8
What is a high V/Q ratio caused by?
ventilation exceeding perfusion
What is a low V/Q ratio caused by?
poor ventilation
What is the distribution of perfusion dependent on?
gravity
Where is the V/Q ratio highest in the lungs? Lowest?
Apex, bases
What is the maximum angle that you should elevate the HOB? Why?
45 degrees. It will cause decrease in blood flow to the lower extermities
What are 3 factors that impair perfusion?
decreased Hgb, decreased Flow, and physiologic shunt
What are issues that can cause decreased Hgb?
anemia, CO poisoning, cancer, GI bleeds
What are issues that can cause decreased flow?
hemorrhage, PE, pulmonary vasoconstriction
What happens with a physiologic shunt?
anatomic left to right cardiac shunt (septal defect, ductus arteriosus)
What happens in a dead space V/Q mismatch?
alveoli are ventilated but not perfused
When would alveolar dead space occur?
only with PE
What are the two types of pulmonary absolute shunts?
pulmonary anatomic and intrapulmonary shunt combined
What happens in an intrapulmonary shunt?
blood is shunting by the alveoli and not receiving oxygen because the alveoli are non-functional
What happens with an anatomical shunt?
blood moves from the right side of the heart to the left side of the heart without ever coming into contact with the alveoli
What percentage of blood normally has a pulmonary anatomic shunt?
2-5%
What are common causes of the shunt-like effect in the lungs?
bronchospasm, hypoventilation, or pooling of secretions
What happens in a patient that has an obstructive lung disease?
an abnormally high amount of air still lingers in the lungs
What are 4 common reasons for obstructive lung disease?
COPD, Asthma, Bronchiectasis, and CF
What does restrictive lung disease cause in the lungs?
stiffness in the lungs which keeps the lungs from fully expanding
What is an inflammatory syndrome marked by disruption of alveolar-capillary membrane caused by an injury to the lung?
Acute Respiratory Distress Syndrome (ARDS)
What are the 4 parts of the clinical definition of ARDS?
acute onset
Bilateral infiltrates on chest Xray
PAWP<18mmHg or no clinical evidence of left ventricular failure
Hypoxemia refractory to O2 Tx
What is the PaO2/FiO2 that is considered Acute Lung Injury vs ARDS?
below 300 for acute lung injury
below 200 for ARDS
What are 4 common causes of ARDS?
Aspiration of gastric contents or other substances
Viral or bacterial pneumonia
sepsis (especially gram-negative infections)
severe massive trauma
6 of the most common s/s of ARDS
Air hunger
Labored/rapid breathing (dyspnea)
Low O2 levels in blood
Cough and fever
Low BP
Confusion
Extreme tiredness
What are the 3 effects of releasing mediators with ARDS?
increased capillary permeability, change in small airway diameter, and injury to pulmonary vasculature
this leads to increased work of breathing and hypoxemia refractory to oxygen therapy
What is the first thing that should be done when ARDS is present?
treat underlying cause
Which fluids should be administered to a patient with ARDS?
normal saline and LR
What medication is given in order to prevent clots in ARDS?
lovenox
What kind of medications are given to patients with ARDS?
infection treatments, vasoactive medications, analgesia, anticoagulants, and PPIs
What is the purpose of using ECMO for ARDS?
maintain oxygenation of the organs while resting the lung giving them time to heal
What is the best position for an ARDS patient?
prone
What is the mortality rate for ARDS?
40-60%
How long does it take for pulmonary function to return back to normal after ARDS?
within 6-12 months
5 NANDA diagnoses related to pulmonary disease
impaired gas exchange, ineffective airway clearance, ineffective breathing pattern, anxiety, pain (acute)
