ABGs Flashcards

1
Q

Arteries to get ABGs from?

A
  • radial artery should be 1st choice: superficial, easily compressed
  • other arteries: femoral and brachial
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2
Q

What can acidosis cause?

A
  • decreased force of cardiac contraction
  • decreased vascular response to catecholamines
  • decreased response to effects and action of certain meds
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3
Q

What can alkalosis interfere w/?

A
  • tissue O2

- neuro and muscle fxn

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4
Q

O2-Hgb dissociation?

A
  • Bohr effect: increased CO2 = decreased pH
  • when pH changes - that changes binding of O2
  • lower the pH the curve moves right, allows O2 to dissociate easier
  • left shift (alkalosis): O2 doesn’t unload as well
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5
Q

What controls the pH?

A
  • diet
  • metabolic prod of CO2
  • regulation through GI tract
  • influence of other lytes
  • buffers
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6
Q

3 systems that maintain pH?

A
- chemical buffering: 
carbonic acid (main buffer) - CO2 is best transported as HCO3- (as CO2 increases so does H+) 
phosphate
plasma proteins
- resp center
- kidneys
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7
Q

How does resp buffer work?

A
  • conc. of CO2, carbonic acid, and HCO3 will trigger resp center
  • RR and tidal vol will be altered to either increase or decrease ventilation
  • response occurs in 1-3 min
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8
Q

How does renal buffer work?

A
  • kidneys can excrete either acid or alkaline urine, thereby adjusting pH of blood:
    excrete or retain HCO3- and H+
    if blood pH decreases then bicarb would be retained to balance out acidity)
  • response takes over hours or even days, but represents a more powerful regulatory system
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9
Q

Onset of action of buffer systems?

A
  • chemical buffer systems occur almost immediately

- respiratory and renal systems act more slowly than chemical buffers, have more capacity than chemical buffers

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10
Q

Causes of resp acidosis?

A
  • CNS depression: meds - narcotics, sedatives, anesthesia
  • impaired muscle fxn: spinal cord injury, neuromuscular diseases, or neuromuscular blocking drugs
  • pulm disorders: atelectasis, pneumonia, pneumothorax, pulmonary edema, bronchial obstruction
  • massive PE
  • hypoventilation due to pain, chest wall injury, or abdominal pain
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11
Q

S/S of resp acidosis?

A
  • resp: dyspnea, resp distress, and/or shallow respiration
  • nervous: HA, restlessness and confusion: if CO2 level extremely high drowsiness and unresponsiveness may be noted (hypoxic)
  • CVS: tachycardia and dysrhythmias
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12
Q

Management of respiratory acidosis?

A
  • increase ventilation
  • causes that can be tx rapidly: pneumo, pain and CNS depression due to med
  • if cause can’tbe readily resolved then will reqr mechanical ventilation
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13
Q

Causes of resp alkalosis?

A
  • psych responses, anxiety or fear
  • pain
  • increased metabolic demads: fever, sepsis, preg, or thyrotoxicosis
  • meds: resp stimulants
  • CNS lesions
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14
Q

S/S of resp alkalosis?

A
  • CNS: light headedness, numbness, tingling, confusion, inability to concentrate and blurred vision
  • dysrhythmias and palpations
  • dry mouth, diaphoresis and tetanic spasms of arms and legs
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15
Q

Management of resp alkalosis?

A
  • resolve underlying problem
  • monitor for resp muscle fatigue
  • when resp muscles become exhausted, acute resp failure may ensue
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16
Q

Causes of metabolic acidosis?

A
  • renal failure
  • DKA
  • anaerobic metabolism (tissue death, lactic acidosis)
  • starvation
  • salicylate intoxication
  • sepsis
17
Q

MUDPILES?

A

increased anion gap metabolic acidosis

  • M: methanol intoxication
  • U: uremia
  • D: diabetic or alcoholic ketoacidosis
  • P: paraldehyde
  • I: isoniazide or Fe overdose
  • L: lactic acid
  • E: ethylene glycol intoxication
  • S: salicylate overdose
18
Q

USED CAR?

A

non-anion gap metabolic acidosis:

  • U: ureteral - sigmoid diversions - reabsorb Cl-, H2O in intestine - secrete bicarb in intestine
  • S: small bowel fistula, saline admin
  • E: endocrinopathies: addison’s, hyperparathyroidism
  • D: diarrhea
  • C: carbonic anhydrase inhibitors
  • A: hyperalimentation (tPA)
  • R: renal tubular acidosis
19
Q

S/S of metabolic acidosis?

A
  • CNS: HA, confusion, restlessness progressing to lethargy, stupor or coma
  • CVS: dysrhythmias
  • KUssmaul’s respirations (big deep fast resp)
  • warm, flushed skin as well as nausea and vomiting
20
Q

Tx of metabolic acidosis?

A
  • tx cause
  • hypoxia of any tissue bed will produce metabolic acids as result of anaerobic metabolism even if paO2 is normal
  • restore tissue perfusion to hypoxic tissues
  • use of bicarb is indicated
  • hydration
21
Q

Causes of metabolic alkalosis?

A
  • ingestion of excess antacids, excess use of bicarb, or use of lactate in dialysis
  • protracted vomiting, gastric suction, hypochloremia, excess use of diuretics or high level of aldosterone
22
Q

S/S of metabolic alkalosis?

A
  • CNS: dizziness, lethargy, disorientation, seizures, and coma
  • M/S: weakness, muscle twitching, muscle cramps and tetany
  • nausea, vomiting, resp depression
  • diff to tx
23
Q

Base excess?

A
  • amt of excess or insufficient level of bicarb:
  • 2 to +2 mEq/L
  • negative base excess indicates a base deficit in blood
  • it is an est of amt of strong acid or base needed to correct metabolic component of acid base disorder
24
Q

Major anion in ECF?

A
  • Cl: it helps maintain osmotic pressure of blood
  • when acidosis occurs, fewer Cl- are reabsorbed
  • other anions have transport maximums and excesses are excreted in urine
25
Q

What is the anion gap?

A
  • unmeasured anions = proteins, phosphates, citrate, sulfate
  • normal is equal to 12
26
Q
pt admitted for severe asthma attack,  been having increasing SOB since admission 3 hrs ago 
ABGs:
pH 7.22
paCO2: 55
HCO3: 25
DX? Tx?
A
  • resp acidosis

- need to improve ventilation and O2 by admin bronchodilators, O2, possible mechanical ventilation

27
Q
55 admitted w/ recurring bowel obstruction has been experiencing intractable vomiting for last several hours:
pH: 7.5
paCO2: 42
HCO3: 33
Dx? Tx?
A
  • metabolic alkalosis

- tx: IV fluids, measures to reduce excess base

28
Q

When does compensation occur in primary resp acidosis?

A
  • when kidneys retain HCO3
29
Q
Pt on hemodialysis and has missed her last 2 appts 
ABG:
pH 7.32 
paCO2 32
HCO3 18
paO2 88 
Dx?
A
  • partially compensated metabolic acidosis
30
Q
Pt w/ hx of COPD presents for resting ABG prior to PFTs:
pH 7.35
paCO2 48
HCO3 28
PaO2 90 
Dx?
A

fully compensated resp acidosis

31
Q
pH 7.51
PaCo2 50
HCO3 40
PaO2 40 (21% O2) 
Dx?
A
  • metabolic alkalosis w/ partial resp compensation