quiz 5 Flashcards
What does the P(a-ET)CO2 tell us?
The difference between arterial CO2 and end tidal CO2
Increases in the difference indicate an increase in deadspace
What can cause dead space?
PE
Loss of circulation
COPD
Being dead (cardiac arrest)
What is dead space?
Ventilation without perfusion
How do you determine the ratio of deadspace to tidal volume
VD/VT ratio
What is the formula for the VD/VT ratio?
PaCO2 - PeTCO2 / PaCO2
What is a normal VD/VT ratio?
.2-.4
What does an elevated VD/VT ratio mean?
An increased amount of deadspace
What can cause respiratory acidosis?
Parenchymal lung disease
Airway disease
Pleural abnormalities
Chest wall abnormalities
Neuromuscular disorders
CNS depressing
What are the diagnostic benchmarks for determining respiratory acidosis?
pH < 7.35
PaCO2 > 45 mmHg
What is the formula to determine an appropriate tidal volume for a patient on a vent with respiratory acidosis?
Desired VT = (known PaCO2 x Known VT) / Desired PaCO2
What is the formula for determining an appropriate RR with a patient on a vent with respiratory acidosis?
Desired RR = (Known PaCO2 x Known RR) / Desired PaCO2
What is the risk of a high respiratory rate?
autoPEEP
How can you determine if a patient has autopeep?
On exhalation, flow will not return to zero before a new breath is given
What can cause respiratory alkalosis?
Metabolic problems
Hypoxia
Medications
CNS disorders
What are the diagnostic benchmarks for diagnosing respiratory alkalosis?
pH > 7.45
PaCO2 < 35 mmHg
What are the most common causes of respiratory alkalosis in vented patients?
hyperventilation …..oops
Pain
Fever
Asynchrony
Hypoxemia
What are the diagnostic benchmarks for determining if someone has metabolic alkalosis?
pH > 7.45
HCO3 > 26 mEq/L
What are the diagnostic benchmarks for determining if someone has metabolic acidosis?
pH < 7.35
HCO3 < 22 mEq/L
What can cause a metabolic acidosis?
Ketoacidosis
Loss of bicarb (diarrhea)
Medications
Lactic acidosis
Toxins
What can cause a metabolic acidosis?
Loss of gastric fluid (vomiting, NG suctioning)
Diuretics
Medications
Will a patient with metabolic alkalosis become apneic?
Apparently not
What are some indications for suctioning?
Patients has a weak cough
Changes in waveform
Deterioration of oxygen saturation
What is the formula for determining the correct suction catheter size?
(ETT size x 3) / 2
What is the appropriate suction pressure for adults?
-100 to -120 mmHg
What is the appropriate suction pressure for children?
-80 to -100 mmHg
What is the appropriate suction pressures for infants?
-60 to -100 mmHg
What are some potential complications from suctioning?
Your patient hating you
Atelectasis
Hypoxemia
Loss of PEEP
Cardiac arrhythmias
Bradycardia
hypo/hypertension
Infection
T/F: For a patient on a vent, a SVN is more effective than an MDI with a spacer
False. MDIs with a spacer have been shown to be more effective than SVNs
What should be considered when giving an MDI through a vent?
Whether or not an HME is being used as it will take the medication out before it reaches the patient
What are some indications for bronchoscopy?
Presence of lesions
Evaluation of atelectasis or pulmonary infiltrates
Assess upper airway patency
Suspicious sputum cytologic results
What are contraindications for a bronchoscopy?
Hemodynamic instability
Poor oxygenation
When performing a bronchoscopy, what piece of equipment should be used to maintain PEEP?
No fucking clue, slides call it a PEEP keep. Probably just need to know that you need something special to maintain PEEP
What is normal urine production?
50-60 ml/hour
1 ml/kg/hour
What is the term for low urine output?
Oliguria
What is the term for high urine output?
Polyuria
What are the 5 drivers of hypoxemia?
Low oxygen tension of inspired gas
Alveolar hypoventilation
Diffusion defect
V/Q mismatch
Shunting
T/F: Healthy individuals have a natural V/Q mismatch
True. the apical sections of the lungs will have more ventilation and less perfusion than the bases which will have more perfusion and less ventilation
What is the most common cause of hypoxemia?
V/Q mismatch
What is a shunt?
Blood that does not participate in gas exchange either because of anatomical layouts or unventilated alveoli
What is ficks law?
Vgas = A/T x Dgas(P1-P2)
Vgas = volume of gas diffusing across a membrane
A = Surface area tension
T = thickness of the membrane
Dgas = diffusibility of the gas (solubility coefficient)
P1-P2 = pressure gradient
What is circulatory hypoxia?
Hypoxia caused by not having enough blood in circulation
Primarily caused by vampires
What is anemic hypoxia?
When you have enough blood (for now) but insufficient red blood cells in the blood
What is histoxic hypocia?
An excellent band name
When you have sufficient blood and RBCs, but for some reason tissues are unable to use the oxygen
What are the two main tools we have to combat hypoxia?
Supplemental oxygen
PEEP
What settings on the ventilator control ventilation?
Control variable
Rate
What settings on the ventilator control oxygenation?
PEEP
FiO2
List some reactive oxygen species
Superoxide ions (O2-)
Hydrogen peroxide (H2O2)
Hydroxyl ions (OH-)
What can large amounts of reactive oxygen species do to the body?
Damage lung tissue
Disrupt cell signaling
Break strands of DNA
What can hyperoxia cause?
Systemic vasoconstriction
Pulmonary vasodilation
Inflammation
Oxidative stress on pulmonary, cardiovascular and neurological systems
Create ROS
What is the normal partial pressure of oxygen in arterial blood?
80-100 mmHg
What is the normal partial pressure of oxygen in venous blood?
40 mmHg
What is the range of the partial pressure of oxygen in the alveoli when on room air and when on 100% oxygen?
100-673 mmHg
What is the oxygen content of mixed venous blood?
15 vol%
What is the normal saturation for mixed venous blood?
75%
75%
What is the oxygen content of arterial blood?
20 vol%
What is normal oxygen delivery? (DO2)
1000 mL/m
What is normal oxygen consumption?
250 ml/min
What are the main goals for oxygenation?
Maintain a PaO2 of 60-90 mmHg
Try to keep FiO2 below 0.5-0.6
Maintain CaO2 at 20 mg/dL
What are the main dangers of prolonged high FiO2?
Oxygen toxicity
Absorption atelectasis
