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Principles of Anesthesia I > E2 - Acid-Base Disorders > Flashcards

E2 - Acid-Base Disorders Flashcards

1
Q

In order to ensure optimal function of enzymatic function, acid-base balance is tightly regulated at what pH?

A
  • 7.35 to 7.45
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2
Q

What causes acidemia?

A
  • Excess production of H+ (in relation to hydroxyl ions)
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3
Q

What causes alkalemia?

A
  • Excess production of OH- (in relation to hydrogen ions)
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4
Q

What is known as the measured hydrogen concentration?

A
  • pH

The Power of Hydrogen

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5
Q

The stability of pH is managed by what three factors?

A
  • CO2 (enters/leaves the body via lungs)
  • HCO3 (enters/leaves the body via kidneys
    Via proximal tubule)
  • H+ (reabsorbed Via distal tubule and collecting duct)
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6
Q

What is the equation to calculate pH?

A

pH = 6.1 + log [serum bicarb/(0.03 x PaCO2)]

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7
Q

How can you tell if an acid-base disorder is a primary disorder with secondary compensation?
A. PaCO2 and HCO3 are equal
B. PaCO2 and HCO3 change in opposite direction
C. Both PaCO2 and HCO3 change in the same direction

A

C. Both PaCO2 and HCO3 change in the same direction

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8
Q

How can you tell if an acid-base disorder is a mixed acid/base problem?
A. PaCO2 and HCO3 are equal
B. PaCO2 and HCO3 change in different direction
C. Both PaCO2 and HCO3 change in the same direction

A

B. PaCO2 and HCO3 change in different direction

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9
Q

What is the Acid/Base Disorder
pH: 7.34
PCO2: 48
HCO3: 24

A

Uncompensated Respiratory Acidosis

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10
Q

What is the Acid/Base Disorder
pH: 7.58
PCO2: 38
HCO3: 29

A

Uncompensated Metabolic Alkalosis

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11
Q

What is the Acid/Base Disorder
pH: 7.28
PCO2: 42
HCO3: 18

A

Uncompensated Metabolic Acidosis

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12
Q

What is the Acid/Base Disorder
pH: 7.48
PCO2: 32
HCO3: 22

A

Uncompensated Respiratory Alkalosis

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13
Q

If your patient has normal lungs, what should their PaO2 be when they are on 60% FiO2?

A
  • PaO2: 240 to 300 mmHg

Normal range of PaO2: 80-100 mmHg
FiO2 of room air is 21%
FIO2 of 60% is about 3x of room air.
PaO2 will be between 240-300 mmHg

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14
Q

Cardiovascular Consequences of Acidosis

A
  • Impaired contractility at pH 7.2
  • Decreased contractility
  • Decreased arterial blood pressure
  • Sensitive to re-entry dysrhythmias
  • Decrease threshold for V-fib
  • Decreased responsiveness to catecholamines at pH 7.1
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15
Q

Nervous System Consequence of Acidosis

A
  • Obtundation
  • Coma
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16
Q

Pulmonary Consequences of Acidosis

A
  • Hyperventilation (d/t compensation, blowing off CO2)
  • Dyspnea
  • Respiratory Muscle Fatigue
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17
Q

Metabolism Consequence of Acidosis

A
  • Hyperkalemia (contributes to reentry dysrhythmias)
  • Insulin Resistance
  • Inhibition of anaerobic glycolysis
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18
Q

Define Respiratory Acidosis

A
  • An acute decrease in alveolar ventilation resulting in increase PaCO2
  • pH < 7.35
  • Caused by respiratory failure
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19
Q

What are the causes of Respiratory Acidosis?

A
  • Drug-induced ventilatory depression
  • Permissive hypercapnia
  • Upper airway obstruction
  • Status asthmaticus
  • Restriction of ventilation (rib fx, flail chest)
  • Disorder of neuromuscular function
  • MH
  • PNA/ Pulmonary Edema, Pleural Effusion
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20
Q

What are the 3 causes of respiratory acidosis r/t anesthesia management?
A. excess bicarb administered
B. inadequate NMBD reversal
C. therapeutic hyperventilation
D. opioid excess
E. CO2 insufflation
F. consequence of pain

A

B. inadequate NMBD reversal
D. opioid excess
E. CO2 insufflation

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21
Q

What are the three categories that can cause Respiratory Acidosis?

A
  • Central ventilation control (neuro disorder/drug induced vent depression)
  • Peripheral ventilation control (neuromuscular disease)
  • VQ mismatch (Pneumonia)
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22
Q

what is a reason that a patient would have slow, shallow breathing ultimately leading to respiratory acidosis?
A. pneumothorax
B. atelectasis
C. sleep apnea
D. somnolence d/t residual opioids

A

D. somnolence d/t residual opioids

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23
Q

what is a peripheral problem that would cause a patient to have rapid, shallow breathing ultimately leading to respiratory acidosis?
A. hemo/pneumothorax
B. bronchospasm
C. sleep apnea
D. residual opioid causing somnolence

A

A. hemo/pneumothorax

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24
Q

what is a reason that a patient would have obstructed breathing ultimately leading to respiratory acidosis?
A. residual NM blockade
B. high spinal
C. bronchospasm
D. atelectasis

A

C. bronchospasm

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25
Q

In acute hypercarbia, if the PaCO2 increases by 10 mmHg, how much will the HCO3 increase for the system to be compensated?
A. 3 mEq/L
B. 10 mEq/L
C. 1 mEq/L
D. 5 mEq/L

A

C. for every 10 mmHg of PaCO2, bicarb should increase by 1 mEq/L

10:1 in acute hypercarbia

10:3 in chronic hypercarbia

takes about 2-3 days for kidneys to increase bicarb levels in order to compensate

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26
Q

In chronic hypercarbia, if the PaCO2 increases by 10 mmHg, how much will the HCO3 increase for the system to be compensated?
A. 3 mEq/L
B. 10 mEq/L
C. 1 mEq/L
D. 5 mEq/L

A

A. 3 mEq/L

10:3 in chronic hypercarbia
10:1 in acute hypercarbia

This is prevalent in COPD patients

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27
Q

Upon arrival at the ICU, the patient has a PaCO2 of 80 mmHg.

What is the expected HCO3 if this patient has compensated acute hypercapnia?

A
  • 28 mEq/L

Normal PaCO2 level: 40 mmHg
Normal HCO3 level: 24 mEq/L
PaCO2 of the patient is 80 mmHg
PaCO2 increased by 40 mmHg
For acute hypercapnia, ↑PaCO2 of 10 mmHg=↑HCO3- of 1 mEq

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28
Q

Upon arrival at the ICU, the patient has a PaCO2 of 80 mmHg.

What is the expected HCO3 if this patient has compensated chronic hypercapnia?

A
  • 36 mEq/L

Normal PaCO2 level: 40 mmHg
Normal HCO3 level: 24 mEq/L
PaCO2 of the patient is 80 mmHg
PaCO2 increased by 40 mmHg
Chronic Hypercapnia: ↑PaCO2 10 mmHg=↑HCO3- 3 mEq
HCO3- increase by 12 mEq/L
Expected HCO3- = 24 + 12 = 36 mEq/L

29
Q

What is the treatment for respiratory acidosis if hypercarbia is marked and CO2 narcosis is present?

A. bolus some bicarb
B. let them just breath off the CO2
C. sternal rub to make them hyperventilate
D. mechanical ventilation

A

D. Mechanical Ventilation

plz

30
Q

What is the caution with reversing chronic hypercarbia with bicarb?
A. Excessive bicarb will cause CNS irritability leading to seizures
B. Excessive bicarb will cause more acidosis
C. Excessive bicarb will cause metabolic alkalosis
D. No caution: bolus that bicarb

A

A. Excessive bicarb will cause CNS irritability leading to seizures

31
Q

Define Metabolic Acidosis.

A

a lowered blood pH signifying an underlying condition

Metabolic Acidosis is secondary to an underlying disorder (fix the problem to fix acidosis)

32
Q

How does the respiratory system fully compensate when someone is in metabolic acidosis?
A. hyperventilating until pH gets back to normal range
B. hypoventilating until pH gets back to normal range
C. Respiratory compensation does not fully counter excessive acid production

A

C. Respiratory compensation does not fully counter excessive acid production

33
Q

Metabolic Acidosis is associated with: select 2.

A. alterations in transcellular ion pumps
B. leftward shift of oxyHb dissociation curve
C. increased ionized calcium
D. decreased ionized calcium

A

A. alterations in transcellular ion pumps
C. increased ionized calcium

and RIGHTward shift of oxyHb dissociation curve

34
Q

What direction will the Oxygen-Hemoglobin Dissociation Curve shift with Metabolic Acidosis?

A

Rightward Shift!

Hb will have decreased affinity for O2 which allows O2 to be released and available to the tissues

35
Q

What is your expected PaCO2 if your HCO3- is 12 mEq/L?
A. 20 mmHg
B. 22 mmHg
C. 24 mmHg
D. 26 mmHg

A

D. PaCO2 = 26 mmHg

PaCO2 = (1.5 x HCO3-) + 8
= (1.5 x 12) + 8
= 26 mmHg

*If PaCO2 is > 26 mmHg, compensation is INADEQUATE *

36
Q

For every 1 mEq/L drop in base excess, PaCO2 should fall ______ mmHg.

A

For every 1 mEq/L drop in base excess, PaCO2 should fall 1.2 mmHg.

Otherwise compensation inadequate!!

37
Q

What is the formula for determining the expected PaCO2 for someone in metabolic acidosis?
A. PaCO2 = 1.5 x (HCO3- + 8)
B. PaCO2 = (1.5 x HCO3-) + 8
C. PaCO2 = 1.5 + (HCO3- x 8)
D. PaCO2 = (1.5 + HCO3-) x 8

A

B. PaCO2 = (1.5 x HCO3-) + 8

KNOW THIS

38
Q

A normal anion gap __________.

A. has a gain of chloride ions
B. increases loss of bicarb
C. maintains electrical neutrality
D. has additional acids

A

C. maintains electrical neutrality

bicarb loss + chloride gain = neutral charges

high anion gap has additional acids in extracellular space

39
Q

Bicarb loss is countered by the net gain of which ion?

A. potassium
B. sodium
C. calcium
D. chloride

A

D. Chloride ions

often called hyperchloremic acidosis

40
Q

Factors that cause metabolic acidosis with a normal anion gap.

A
  • Sodium Chloride Infusion
  • Diarrhea
  • Early Renal Failure
41
Q

What defines a high anion gap?

A
  • Additional acid that is added to extracellular space
  • Acids dissociates into H+ that combine with bicarb to form carbonic acid that decrease available bicarb
42
Q

Causes of high anion gap.

A
  • Lactic Acidosis
  • Ketoacidosis
  • Renal Failure
  • Poisoning
43
Q

What is the simple anion gap formula?

What is the range of a simple anion gap?

A
  • Sodium - (Chloride + Bicarb)
  • 12-14 mEq/L
44
Q

What is the conventional anion gap formula?

What is the range of a conventional anion gap?

A
  • (Sodium + Potassium) - (Chloride + Bicarb)
  • 14-18 mEq/L
45
Q

Anion Gap frequently ___________ (overestimates/underestimates) the extent of acid-base disturbances.

A
  • Underestimates

This is complicated by hypoalbuminemia and hypophosphatemia

46
Q

How do you treat metabolic acidosis?

A
  • Treat the cause!
47
Q

Treatment for Metabolic Acidosis related to Ketoacidosis.

A
  • Insulin and fluids
48
Q

Treatment for Metabolic Acidosis related to Lactic Acidosis.

A
  • Improve tissue perfusion
49
Q

Treatment for Metabolic Acidosis related to Renal Failure.

A
  • Dialysis
50
Q

What are the parameters to treat metabolic acidosis with sodium bicarbonate?

A
  • pH < 7.1
  • HCO3- < 10 mEq/L
51
Q

What are the negative effects of administering bicarb to someone with metabolic acidosis?

A
  • Bicarb will react with H+ ion and generate CO2 which will diffuse intracellularly and decrease pH
  • In chronic metabolic acidosis, acute pH changes negate the right shift curve (Bohr effect) and cause tissue hypoxia

The administration of IV NaHCO3 to treat metabolic acidosis should be reserved for the emergency treatment of select conditions

52
Q

Formula for HCO3- Correction Dose

A
  • Dose of Bicarb = 0.3 x Base Deficit x Wt (kg)

Oftentimes, you would give half this dose and reassess

53
Q

What happens to elective surgery if the patient experience acute metabolic acidosis?

A
  • Surgery will be postponed
54
Q

Anesthesia management considerations for urgent/emergent surgery with metabolic acidosis.

A
  • Hemodynamic monitoring
  • Give Fluids
  • Monitor Cardiac Functions
  • Frequent Lab
  • Uphill battle, be honest with family members
55
Q

Define Respiratory Alkalosis.

A
  • An acute increased alveolar ventilation
  • Results in ↓ PaCO2 and pH > 7.45
56
Q

What are the causes of Respiratory Alkalosis?

A
  • Pregnancy
  • High Altitude (↑RR)
  • Salicylate overdose (asprin)
  • Iatrogenic hyperventilation (during perioperative period/ fear)
57
Q

What are the symptoms of Respiratory Alkalosis?

A
  • Decrease PaCO2 will cause vessel constriction
  • Lightheadedness
  • Visual disturbance
  • Dizziness
58
Q

Respiratory Alkalosis will result in greater binding of calcium to ________.

A
  • Albumin

Patient will be hypocalcemic.

59
Q

What are the signs and symptoms of hypocalcemia?

A
  • Paresthesia, muscle spasm, cramp, tetany, circumoral numbness, seizures
  • Trousseau’s sign
  • Chvostek’s sign (Irritability on the facial nerve)
60
Q

How many branches of the facial nerve are there?

Name them :)

A

Five Branches:
* Temporal
* Zygomatic
* Buccal
* Mandibular
* Cervical

Two Zebras Bit My Chicken

61
Q

Anesthesia management of respiratory alkalosis.

A
  • Consider what is causing the hyperventilation (anxiety)
  • Consequence of Pain, Full Bladder, Agitation
  • Poor mechanical ventilation strategy
  • Therapeutic Hyperventilation
62
Q

Define Metabolic Alkalosis.

A
  • Marked increase in plasma bicarb usually compensated by an increase in CO2
  • Renal or extrarenal causes
  • Net loss of H+ or a net gain of bicarb
63
Q

What are other names for Metabolic Alkalosis?

A
  • Volume depletion alkalosis
  • Volume overload alkalosis
64
Q

What are the causes of Metabolic Alkalosis?

A
  • Hypovolemia
  • Vomiting
  • NG suction
  • Diuretic Therapy
  • Bicarb administration
  • Hyperaldosteronism (Conn’s ↑ Na+, ↓ K+)
65
Q

Treatment for Metabolic Alkalosis?

A
  • Treat the cause!
66
Q

Treatment for Metabolic Alkalosis related to volume depletion.

A
  • Saline fluid resuscitation
67
Q

Treatment for Metabolic Alkalosis related to gastric loss.

A
  • Proton Pump Inhibitors
68
Q

Treatment for Metabolic Alkalosis related to loop diuretics.

A
  • Potassium-sparing diuretics (Spironolactone)

Principles of Anesthesia I (27 decks)

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