ABGs ☺️ Flashcards

1
Q

What are the normal ranges for

  • pH
  • PO2, PCO2, HCO3
  • lactate, base excess
  • SaO2
A
pH - 7.35-7.45
PO2 - 10-13
SaO2 - 98%
PCO2 - 4.7-6.0
HCO3 - 22-26
Base excess - -2-+2
Lactate - U2
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2
Q

Describe how to interpret the ABG

A
  1. Look at the patient
  2. Hypoxemic? - SaO2 under 10
  3. pH => acidemic or alkalemic? Mixed or fully compensated? Partial compensation?
  4. Resp PCO2 derangement?
    5 Metabolic HCO3 derangement?
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3
Q

What are common causes of resp acidosis

-hypoventilation

A

Lung issues

  • acute/chronic lung diseases
  • airway obstruction

Drug issues
-sedatives: BZ, opiates

NM issues

  • NM disease: Guillain Barre, Myasthenia Gravis,
  • obesity hypoventilation syndrome
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4
Q

How does respiratory acidosis present?

Management?

A

Respiratory distress, shallow breaths
CO2 narcosis: Headache , restless, confusion, drowsy
High HR

O2 if needed
Assess and manage cause
Ventilation may be needed

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5
Q

Common causes of respiratory alkalosis

Hyperventilation

A

Lung issues

  • PE, PT
  • high altitude
  • asthma/COPD exacerbation

CNS (direct stimulation of resp centres)
-stroke, SAH, encephalitis

Drugs
-salicylates

Psych
-anxiety

Other
-pregnancy

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6
Q

How does resp alkalosis present?

-management

A

Numbness, light headed
Nervous
Hyperventilation

Muscle cramps, tingling
LOC, death

Management

  • manage underlying cause
  • O2 if sats are low
  • ventilation may be needed
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7
Q

Common causes of metabolic acidosis

-normal anion gap

A

Normal anion gap - 8-12 due to
HCO3 U22

Hyperalimentation - associated with high Cl
Addisons - high K => high Cl
Renal tubular acidosis - loss of HCO3
Diarrhoea - loss of HCO3
Acetazolamide - diuretic/CAinh => loss of HCO3
Spirinolactone - high K => high Cl
Saline infusion - high Cl

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8
Q

How to calculate the anion gap

A

(Na + K) - (Cl + HCO) = 8-12

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9
Q

Common causes of metabolic acidosis

-increased anion gap

A

12+ due to increased H that has to be buffered by HCO3
U22

Methanol (antifreeze)
Uraemia - decreased H excretion
DKA (diabetic, alcohol, malnutrition)
Propylene glycol (antifreeze)
Iron tablets
Lactic acidosis
Ethylene glycol (antifreeze)
Salicylate
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10
Q

Presentation of metabolic acidosis

Management

A

Nausea, vomiting, SOB/Kussmaul
Headache, confusion

Monitor ECG, SaO2
Assess for cause
Be prepared to ventilate

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11
Q

Common causes of metabolic alkalosis

A

HCO3 26+
Loss of acid

Hyperaldosteronism
Antacids
Loop diuretics
Vomiting

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12
Q

Presentation of metabolic alkalosis

Management

A

Hypoventilation due to inhibition of resp center in medulla
Confusion

SaO2, ECG monitoring
Assess cause
Be prepared to ventilate

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13
Q

Examples of mixed acidosis and alkalosis

A

Mixed resp and met acidosis

  • cardiac arrest
  • multi organ failure

Mixed resp and met alkalosis

  • cirrhosis+diuretics
  • hyperemrsis gravidarum
  • excess ventilation in COPD

Resp alk, met acid
-salicylate poisoning

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