Blood Gas and Acid Base Flashcards
(28 cards)
Why do you not want a venous sample for blood gas?
does not give direct measurement of arterial oxygenation
How do you properly collect a sample for blood-gas?
use a heparinized syringe and fill it completely to prevent diffusion of gases into air space at the top of the tube
How do you store a sample collected for blood-gas?
store at room temp. for up to 30 mins. before changes in acid-base will be seen
changes in PO2 will occur in 12 mins.
if analysis cannot be performed immediately, place sample in a 4 degree water bath for no longer than 3 hrs
At physiologic pH of ____ 95% of potential CO2 gas is in the form of _______.
At physiologic pH of 7.4, 95% of potential CO2 gas is in the form of bicarbonate.
When analyzing HCO3 and PCO2 for Acid-Base eval., which refers to metabolic changes and which refers to respiratory changes?
HCO3- : metabolic
PCO2 : respiratory
Compensatory changes are in response to primary acid-base changes. Primary acid-base changes go with/against the direction of pH.
Primary acid-base changes go WITH the direction of pH.
What is Base Excess/Base Deficit?
Metabolic non-respiratory component that reflects acid-base regulating ability of the kidneys (HCO3-) and the blood (hemoglobin) buffer system.
Base Excess =
Alkalosis
Base Deficit =
Acidosis
Metabolic Compensatory Mechanisms…for each 1mEq/L change in HCO3-, you expect…
0.7mmHg change in pCO2 in the same direction
Acute Respiratory Acidosis..for each 1mmHg change in pCO2, you expect…
0.15mEq/L change in HCO3-
Chronic Respiratory Acidosis…for each 1mmHg change in pCO2, you expect…
0.35mEq/L change in HCO3-
Acute Respiratory alkalosis…for each 1mmHg change in pCO2, you expect..
0.25mEq/L change in HCO3-
Chronic Respiratory alkalosis…for each 1mmHg change in pCO2, you expect…
0.55mEq/L change in HCO3-
What does blood gas measure?
pH pO2 pCO2 HCO3- O2 Sat.
What effect does PTH have on Ca2+ and Ph?
PTH –> Increase Ca2+ and Decrease Ph
What effect does Calcitriol (activated Vit. D) have on Ca2+ and Ph?
Calcitriol –> Increase Ca2+ and Increase Ph
What effect does Calcitonin have on Ca2+ and Ph?
Calcitonin –> Decrease Ca2+ and Decrease Ph
In small animal, hypocalcemia CSs are…
muscle tremors/convulsions, ataxia, flaccid paralysis, weakness and tetany
In horse, hypocalcemia CSs are..
synchronous diaphragmatic flutter, tetany, stilted gait, muscle tremors, recumbency, convulsions, and cardiac arrhythmias
In cows, hypocalcemia CSs are…
weakness and recumbency
What causes hypocalcemia?
renal disease
pancreatitis
parturition
In a patient w/ renal disease and hypocalcemia, the renal disease if often secondary to..
hyperparathyroidism
PTH is stimulated from low iCa2+ –> Vit D production impaired due to renal insufficiency –> metabolic acidosis will mask hypocalcemia even if total Ca2+ is decreased
In a patient w/ pancreatitis and hypocalcemia…
Ca2+ is binding to fat –> decreases [Ca2+]
