Normal Values
what is a normal for PaCO2?
What is a normal PaO2?
35-45 mmHg
70-100 mmHg
base excess
Minute ventilation increases ____ L/min every 1mmHg increase in PaCO2.
A. 2-5
B. 1-4
C. 6-10
D. 1-2
B. 1-4
(actual oxygen content/ maximum oxygen capacity) x 100
A patient presents with the following ABG and electrolyte values:
What is the primary acid-base disturbance?
uncompensated respiratory acidosis
The low pH indicates acidosis. The elevated PaCO2 suggests a respiratory cause. Since HCO3- is normal and hasn't increased, this is uncompensated respiratory acidosis.
6.8
cells produce excess acid during metabolism in the form of carbonic acid
What are the three ways the body responds to changes in H+ concentrations (Bonus if you can put them in order of fastest to slowest response)!
Buffer system (seconds)
Respiratory (minutes)
Renal (hours to days)
Renal is the most powerful response
Pulmonary responses to metabolic distrubances:
PaCO2 decreases by _____ below 40mmHg for every 1mEq/L decrease in bicarb.
AND
PaCO2 increases by _____ below 40mmHg for every 1mEq/L decrease in bicarb.
A. 0.25-1 mmHg and 1-1.5 mmHg
B. 3-5 mmHg and 4-6 mmHg
C. 1-1.5 mmHg and 0.25-1 mmHg
D. 4-6 mmHg and 3-5 mmHg
C. 1-1.5 mmHg and 0.25-1 mmHg
How can you estimate PaO2 of a healthy individual breathing room air at sea level?
102- (age/3)
A patient with chronic obstructive pulmonary disease (COPD) presents with the following ABG and electrolyte values:
What is the primary acid-base disturbance, and is it compensated?
fully compensated respiratory acidosis
The pH is within the normal range but slightly on the acidic side, indicating a fully compensated state. The elevated PaCO2 suggests a respiratory cause, and the elevated HCO3- indicates metabolic compensation.
What is a normal bicarb (HCO3) ?
22-26 mEqs/L
This is the chemical equation for the bicarbonate buffer system (H20+ CO2 = H2CO3 = H+ + HOC3) which is inherently a slow reaction.
What is the enzyme needed to speed it up?
carbonic anhydrase
Select all that apply: What are the undesirable effects of Bicarb administration?
A. hyponatremia
B. hyperosmolality
C. volume overload
D. left shift of the oxyhemoglobin dissociation curve
E. acceleration of lactate formation
F. hypercarbia
A. hyponatremia (hypernatremia)
B. hyperosmolality
C. volume overload (d/t hyperosmolality)
D. left shift of the oxyhemoglobin dissociation curve
E. acceleration of lactate formation
F. hypercarbia
G. CSF alkalosis (acidosis)
Your patient's Sodium is 142, and Chloride 103, Bicarb 18. Calculate their anion gap:
Anion gap= [Na+] - ([Cl-]+[HCO3])
= [142] - ([103] + [18])
= 21
A patient is admitted with severe diarrhea and presents with the following ABG and electrolyte values:
What is the primary acid-base disturbance, and is it compensated?
uncompensated metabolic acidosis
The low pH indicates acidosis. The low HCO3- suggests a metabolic cause, and the normal PaCO2 indicates that there is no respiratory compensation yet, so this is uncompensated metabolic acidosis.
What is a normal base excess/deficit?
+2 to -2 mEqs/L
It is questionable to give large Sodium Bicarb to patients in cardiac arrest or low-flow states due to paradoxical acidosis. This is caused by a build-up of which compound?
A. lactic acid
B. carbonic anhydrase
C. CO2
D. ammonia
C. CO2
the bicarb combines with H+ to make carbonic acid which is then broken down into CO2 and H2O. In low-flow states, there is impaired CO2 elimination, so the CO2 will accumulate and cause acidosis.
What are the two extracellular compartment buffer systems?
bone demineralization: acid loads demineralize bone and release alkaline compounds
Ion exchange: exchange of extracellular H+ for Na+, Ca++, and K+ (can lead to hyperkalemia)
calculate bicarb dose:
BE= -6
Weight (kg)= 70
Bicarb = BE x 30% x body weight (kg)
= (6) x .03 x 70
= 126 mEq
However, in practice, you would only give 1/2 of the calculated dose so about a little over 1 amp (50meq) of Bicarb or 63meq.
A patient with a history of anxiety presents with the following ABG and electrolyte values:
What is the primary acid-base disturbance, and is it compensated?
uncompensated respiratory alkalosis
The high pH indicates alkalosis. The low PaCO2 suggests a respiratory cause. Since HCO3- is normal, this is uncompensated respiratory alkalosis.
What is a normal anion gap?
< 7-14 mEq/L
Categorize each item by if they shift the oxyhemoglobin dissociation curve to the left or right?
- Increase 2,3 DPG
- acidosis
-alkilosis
- decrease 2,3 DPG
- hyperthermia
- hypothermia
- increased CO2
- decreased CO2
Right (reduced affinity for O2): tissues
- Increase 2,3 DPG
- acidosis
- hyperthermia
- increased CO2
Left (increased affinity for O2): lungs
- decreased 2,3 DPG
- alkalosis
- hypothermia
- decreased CO2
Match the condition to its metabolic disturbance (metabolic v resp acidosis or alkalosis):
A. Lung disease (ie. PNA)
B. Ketoacidosis
C. drugs (salicylates, progesterone, doxapram)
D. massive blood transfusion
A = resp acidosis
B= metabolic acidosis
C= resp alkalosis
D= metabolic alkalosis
Which of these is not a result of Acidemia?
A. increased V-fib threshold
B. decreased responsiveness to catecholamines
C. progressive hyperkalemia
D. decreased myocardial and smooth muscle depression (hypotension)
A
it decreases the threshold making them more susceptible to V-fib
A patient with a history of heart failure presents with the following ABG and electrolyte values:
What is the primary acid-base disturbance, and is it compensated?
partially compensated metabolic alkalosis
The high pH indicates alkalosis. The elevated HCO3- suggests a metabolic cause, and the slightly elevated PaCO2 indicates that the respiratory system is beginning to compensate but not fully, so this is partially compensated metabolic alkalosis.