ABGs Flashcards by Morgan Stone

purpose of ABGs

to assess acid-base status and to determine adequacy of oxygenation and ventilation

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pH normal range and purpose

–7.35-7.45
–balance of H+

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PaCO2 normal range and purpose

–35-45
–respiratory parameter
–carbonic acid dissolves into CO2 and H2O

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HCO3 normal range and purpose

–22-26
–metabolic parameter
–measured HCO3 is reported as CO2 on a chem panel

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PaCO2

partial pressure of CO2 in artery

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components of ABG

–pH (7.35-7.45)
–PaCO2
–HCO3

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components of VBG

–pH (7.31-7.41)
–PvCO2 (41-51)
–HCO3

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PvCO2

partial pressure of CO2 in vein

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BMP

serum CO2 = HCO3 level (22-26)

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primary event

the problem that initiates the acid-base imbalance (hypoventilation, hyperventilation, vomiting, diarrhea, etc.)

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primary disorder

what results from the primary event (respiratory acidosis, metabolic alkalosis, etc.)

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compensation mechanisms

physiologic processes that adjust the pH back to the normal range
–lungs are problem = kidneys compensate
–kidneys are problems = lungs compensate

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metabolic cause of imbalance

–HCO3 level changes secondary to metabolic alterations
–the PROBLEM is metabolic in nature

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respiratory cause of imbalance

–H2CO3 level changes secondary to respiratory alterations
–the PROBLEM is respiratory in nature

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respiratory acidosis and alkalosis

–increase or decrease in CO2
–changes in ventilation

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metabolic acidosis and alkalosis

changes in H+ or bicarb ions

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acid base pneumonic

R(espiratory)
O(pposite)
M(etabolic)
E(qual)

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‘Respiratory Opposite’

–pH high, CO2 low (alkalosis)
–pH low, CO2 high (acidosis)

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‘Metabolic Equal’

–pH high, HCO3 high (alkalosis)
–pH low, HCO3 low (acidotic)

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metabolic alkalosis

too much bicarb or not enough carbonic acid

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ABGs for metabolic alkalosis

pH > 7.45
PaCO2 : 35-45
HCO3 > 26

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causes of metabolic alkalosis

–taking excess baking soda or alka-seltzer = too much base
–prolonged vomiting
–NG tube
–diuretics

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effect of taking too much baking soda or antacids

hypokalemia causing hydrogen to shift out of the intracellular space and potassium goes into the cell

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symptoms of metabolic alkalosis

–CNS over-excitability
–confusion
–tremors
–muscle cramps
–paresthesias
–coma
–N/V/D
–respiratory depression
–hypoventilation (compensatory)
–tachycardia
–hypokalemia

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respiratory alkalosis

--H2CO3 deficit in ECF --hyperventilation --> primary event --> CO2 blown off

ABGs for respiratory alkalosis

--pH > 7.45 --PaCO2 < 35 --HCO3 = 22-26

common causes of respiratory alkalosis

--hyperventilation --increased metabolic demands --meds --acute anxiety --hypoxia --PE or lung disease --CNS lesions --vent settings

symptoms of respiratory alkalosis

--tachypnea --light headedness --confusion, blurred vision --paresthesia --hyperactive reflexes (seizures) --coma

respiratory acidosis

H2CO3 in excess

primary event in respiratory acidosis

hypoventilation

primary event for respiratory alkalosis

hyperventilation

ABGs for respiratory acidosis

--pH < 7.35 --PaCO2 > 45 --HCO3 = 22-26

when is HCO3 WNL for respiratory acidosis?

acute respiratory acidosis **no time for kidneys to compensate**

signs of respiratory acidosis

--hypoventilation --dyspnea --respiratory distress --shallow respirations --headache, restlessness, confusion --tachycardia, arrythmias --decreased LOC, stupor, coma

common causes of respiratory acidosis

--cardiopulmonary arrest --head injury --narcotics/sedatives --anesthesia --pulmonary disorders --pain --abdominal distention --airway obstruction --chest wall deformities --neuromuscular problems (ALS)

metabolic acidosis

HCO3 deficit in ECF --excess acids are added or bicarb is lost

ABGs for metabolic acidosis

--pH < 7.35 --PaCO2 = 35-45 --HCO3 < 22

CO2 and compensation with metabolic acidosis

if lungs are compensating, the CO2 will be decreased

symptoms of metabolic acidosis

--lethargy, drowsiness --confusion --tremors, muscle cramps --paresthesias --hypotension --hyperkalemia --deep breathing (Kussmaul's respirations) --fruity odor breath (DKA)

common causes of metabolic acidosis

--renal failure --fistulas --diabetes (Type 1) --lactic acidosis --prolonged diarrhea --starvation --medication overdose (aspirin) --shock and cardiac arrest

respiratory acidosis/alkalosis compensation

kidneys compensate by either: (1) conserving (reabsorbing) HCO3 (2) excreting HCO3 **hours to days

metabolic acidosis/alkalosis compensation

lungs compensate by either: (1) conserving CO2 ions (2) excreting CO2 ions **kidneys also attempt to correct imbalance by retaining/excreting HCO3 **minutes to hours

rate of compensation with respiratory

rapid

rate of compensation with metabolic

slow

major organ involved in respiratory compensation

lungs

major organ involved in metabolic compensation

kidneys

compensatory mechanism of lungs

hyper/hypoventilation

compensatory mechanism of kidneys

retention/excretion of H+/HCO3

acid-base problem triggering activation of compensation in respiratory

metabolic A-B abnormalities

acid-base problem triggering activation of compensation in metabolic

respiratory A-B abnormalities

interventions for respiratory acidosis

measures to improve ventilation --increase rate/depth of RR --stimulate patient/encourage slow and deep respirations --give sodium bicarb

fully compensated respiratory acidosis

--pH normal, leaning acidic --PaCO2 high --HCO3 high

uncompensated respiratory alkalosis

pH high PaCO2 low HCO3 WNL

interventions for respiratory alkalosis

--calm patient --breathe into paper bag --anti-anxiety meds --rebreather

fully compensated respiratory alkalosis

pH normal, leaning basic PaCO2 low HCO3 low

metabolic acidosis physiology

--pH is down and metabolic acidosis presents as low HCO3 --lungs compensate by increasing the rate and depth of respirations to blow off CO2, moving pH back toward a more normal state

treatment for metabolic acidosis

admin rapid acting insulin to bring BG down

uncompensated metabolic acidosis

pH low PaCO2 normal HCO3 low

partially compensated metabolic acidosis

pH low PaCO2 low HCO3 low

fully compensated metabolic acidosis

pH normal (leaning acidic) PaCO2 low HCO3 low

physiology of metabolic alkalosis

--pH is increased and metabolic alkalosis is present as indicated by high HCO3 --lungs compensate by decreasing rate and depth of respirations to hold on to CO2

uncompensated metabolic alkalosis

pH high PaCO2 normal HCO3 high

partially compensated metabolic acidosis

pH low PaCO2 low HCO3 low

fully compensated metabolic acidosis

pH normal (leaning low) PaCO2 low HCO3 low

pH "leaning toward acid"

pH < 7.4

pH "leaning toward base"

pH > 7.4

uncompensated

--pH abnormal --acid OR base abnormal

partially compensated

--pH abnormal --acid AND base abnormal

fully compensated

--pH normal (leaning acid or base) --acid or base abnormal, but balanced (arrows moving in same direction)

corrected

--pH WNL --all acid or base parameters WNL

COPD patient balance

compensated, but not corrected

ABGs Flashcards

(71 cards)