Partial Compensation, Full Confusion
What is the interpretation of this ABG and oxygenation status?
pH-7.26, PaCO2- 59mm Hg, HCO3- 24mEq/L, PaO2- 82mm Hg, SaO2 96%
AVF with a normal oxygenation status
What is the purpose of the pulmonary (semilunar) valve?
This valve prevents blood from returning to the right ventricle after injection (backflow).
Given the following values, calculate the DO2. CO- 5mL, PaO2- 80mm Hg, CaO2-21mL, SpO2- 95%
DO2= CO x 10 x CaO2
5 x 10 x 21 = 1,050mL O2/min
What are common causes of hyperventilation?
Hypoxemia: The most common cause of hypoxemia is V/Q mismatch
Other acceptable: Metabolic acidosis (Kussmaul's), anxiety, fever/sepsis, drugs, hormones, CNS disorders.
What is the primary method of CO2 transport?
bicarb(HCO3-) with catalyst carbonic anhydrase
What is the interpretation of this ABG
pH-7.23, PaCO2- 42mm Hg, HCO3- 25mEq/L, PaO2-89mm Hg, SaO2- 97%
Error in acid/base
*Run the HH eq if you suspect error
pH= 6.1 +log ([HCO3-]/(PaCO2*0.03))
Plug in -> 6.1 +1.29 = 7.39 <- doesnt equal 7.23
What does the Frank-Starling law state about venous return and stroke volume?
Increased venous return (increased preload) increases stroke volume
What does carbonic anhydrase do?
To catalyse the carbon dioxide CO2 and water H2O to form carbonic acid H2CO3, which then dissociates to bicarbonate HCO3- and H+ ions
CO₂ + H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃⁻.
What is the range of PaCO2 we keep for patients with AHI?
Maintain PaCO2 in a normal low range (30-35) to maintain ICPs by promoting cerebral vasoconstriction.
What are the 4 types of hypoxia?
Hypoxemic, anemic, circulatory (stagnant), and histotoxic hypoxia.
What is the interpretation of this ABG and oxygenation status?
pH-7.20, PaCO2- 83mm Hg, HCO3- 33mEq/L, PaO2- 56mm Hg, SaO2- 87%
Acute on chronic ventilatory failure with moderate hypoxemia.
What can a high heart rate affect and how? (In terms of SV, CO, and perfusion)
Coronary arteries primarily receive blood flow during diastole, when the heart muscle relaxes. When the heart rate increases significantly, diastolic time shortens, leaving less time for the coronary arteries to fill. This reduced diastolic period also limits ventricular filling, which decreases stroke volume (SV). As a result, very rapid heart rates can reduce both coronary perfusion and overall cardiac output.
If you see a Black CXR, what could be a potential problem?
Normal, any obstructive diseases, increased Deadspace ventilation
You run an ABG on a patient and get the following values. pH-7.14, PaCO2- 40 mm Hg, HCO3- 13 mm Hg. What is the interpretation of this blood gas in Wettstinese?
Metabolic acidosis with possible respiratory compromise. The potential respiratory compromise comes from the PaCO2 being normal and not trying to compensate (it’s not doing its job)
A patient comes in from a house fire. What steps should be taken in treating them upon arrival at the ED?
Patient should receive a very high amount of oxygen (100%) by NRBM, then use a co-oximetry to monitor their CoHb levels. If it is less than 30% then the patient does not have to be placed into a Hyperbaric chamber.
Your patient has a 70 pack-year history of smoking and was diagnosed last year as having moderate COPD. Based on the following ABG, what's the primary acid/base problem and oxygenation status?
pH-7.37, PaCO2- 45mm Hg, HCO3- 25mEq/L, PaO2- 68mm Hg, SaO2- 98%
Patient has normal ABG with mild hypoxemia, as these values are normal for a COPD patient in this stage of COPD
Why is the heart muscle more blood flow dependent than skeletal muscle?
Because the myocardium uses up to 75% of the oxygen received, and it cannot increase extraction so it requires consistent blood flow.
Explain the difference between Bohr and Haldane effects
The Bohr effect looks at CO2’s impact on Hb affinity for O2.
While the Haldane effect looks at O2's impact on Hb affinity for O2
Explain why a polycythemia may be cyanotic but not be experiencing any tissue hypoxia
In polycythemia, patients have an increased total hemoglobin concentration.
Cyanosis occurs when ≥5 g/dL of reduced (deoxygenated) hemoglobin is present, regardless of total Hb.
Because they have so much Hb, they can appear cyanotic even when PaO₂ and tissue oxygenation are adequate.
What are the causes of a right shift?
Causes of right shift: ↑ temperature, ↑ PaCO₂, ↑ 2,3-DPG, ↓ pH (acidosis).
Your patient is breathing 14b/min, VT 450mL, HR 82, with no accessory muscle use. Using the following ABG values, what is the primary acid/base problem?
pH- 7.35, PaCO2- 47mm Hg, HCO3- 24mEq/L, PaO2- 40mm Hg,SaO2- 77%
Venous blood gas
See Slideshow
A- Superior Vena Cava
B- Right Atrium
C- Tricuspid valve
D- Right Ventricle
E- Pulmonary Valve (semilunar)
F-Pulmonary artery
G-Pulmonary Vein
H- Left Atrium
I- Mitral Valve
J- Left Ventricle
K- Aortic Valve
L- Aorta
A 40-year-old patient is breathing on room air at sea level; An ABG is drawn and the PaCO2 is 50mm Hg. Calculate the PaO2
PaO2= (Pb-47)(FiO2) - PaCO2/R
(760-47)(.21)-50/0.8= 87.23mm Hg
What happens in zone 1 of West's lung flow
Alveolar pressure exceeds both arterial and venous pressure, resulting in dead space
identify whether the curve is normal, right-shifted, or left-shifted if a patient has an SaO₂ of 90% at a PaO₂ of 50 mm Hg.
Right shift.
*Hemoglobin has a decreased affinity for O₂ — it releases oxygen to tissues more easily. Therefore, at any given SaO₂, the PaO₂ will be higher than normal (e.g., 90% SaO₂ at 50 mm Hg instead of 60 mm Hg).