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24 ANE 8509 Principles of Anesthesia I > Exam 2- Acid-Base Disorders (6/22/23) > Flashcards

Exam 2- Acid-Base Disorders (6/22/23) 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
  • 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 in different directions.
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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 three categories that can cause Respiratory Acidosis?

A
  • Central ventilation control (neuro/brain)
  • Peripheral ventilation control (neuromuscular disease)
  • VQ mismatch (Pneumonia)
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21
Q

With acute hypercarbia, how long does it take for the bicarb to compensate for the acid-base disorder?

If PaCO2 increases by 10 mmHg, this will increase _______ mEq/L of HCO3- for the system to be compensated.

A
  • Very slowly (2-3 days)
  • Increase in 1 mEq/L of HCO3 for every 10 mmHg of PaCO2
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22
Q

How much will HCO3- increase with compensated chronic hypercarbia?

A
  • ↑ PaCO2 of 10 mmHg = ↑ HCO3- by 3 mEq/L

This is prevalent in COPD patients

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23
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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24
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

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25
Q

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

A
  • Mechanical Ventilation
26
Q

Why should there be caution with chronic hypercarbia reversal with bicarb?

A
  • Excessive bicarb will cause CNS irritability leading to seizures
27
Q

Define Metabolic Acidosis.

A
  • A lowered blood pH which stimulates the respiratory center to hyperventilate
  • Metabolic Acidosis is secondary to an underlying disorder (fix the problem to fix acidosis)

Respiratory compensation does not fully counter excessive acid production

28
Q

Metabolic Acidosis is associated with alterations in transcellular ____________ and ↑ ionized calcium.

A
  • ion pumps
29
Q

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

A
  • Rightward Shift
  • This will allow O2 to be released and available to the tissues
30
Q

What is your expected PaCO2 if your HCO3- is 12 mEq/L?

A
  • PaCO2 = 26 mmHg
  • If PaCO2 is > 26 mmHg, compensation is INADEQUATE

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

31
Q

For every 1 mEq/L of negative base excess, PaCO2 should fall ______ mmHg.

A
  • 1.2 mmHg
32
Q

A normal anion gap maintains __________.

A
  • Electrical neutrality
33
Q

Bicarb loss is countered by the net gain of ______ ions.

A
  • Chloride ions
  • This is often called hyperchloremic acidosis
34
Q

Factors that cause metabolic acidosis with a normal anion gap.

A
  • Sodium Chloride Infusion
  • Diarrhea
  • Early Renal Failure
35
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
36
Q

Causes of high anion gap.

A
  • Lactic Acidosis
  • Ketoacidosis
  • Renal Failure
  • Poisoning
37
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
38
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
39
Q

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

A
  • Underestimates

This is complicated by hypoalbuminemia and hypophosphatemia

40
Q

How do you treat metabolic acidosis?

A
  • Treat the cause!
41
Q

Treatment for Metabolic Acidosis related to Ketoacidosis.

A
  • Insulin and fluids
42
Q

Treatment for Metabolic Acidosis related to Lactic Acidosis.

A
  • Improve tissue perfusion
43
Q

Treatment for Metabolic Acidosis related to Renal Failure.

A
  • Dialysis
44
Q

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

A
  • pH < 7.1
  • HCO3- < 10 mEq/L
45
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

46
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

47
Q

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

A
  • Surgery will be postponed
48
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
49
Q

Define Respiratory Alkalosis.

A
  • An acute increased alveolar ventilation
  • Results in ↓ PaCO2 and pH > 7.45
50
Q

What are the causes of Respiratory Alkalosis?

A
  • Pregnancy
  • High Altitude (↑RR)
  • Salicylate overdose (asprin)
  • Iatrogenic hyperventilation (during perioperative period/ fear)
51
Q

What are the symptoms of Respiratory Alkalosis?

A
  • Decrease PaCO2 will cause vessel constriction
  • Lightheadedness
  • Visual disturbance
  • Dizziness
52
Q

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

A
  • Albumin

Patient will be hypocalcemic.

53
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)
54
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

55
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
56
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
57
Q

What are other names for Metabolic Alkalosis?

A
  • Volume depletion alkalosis
  • Volume overload alkalosis
58
Q

What are the causes of Metabolic Alkalosis?

A
  • Hypovolemia
  • Vomiting
  • NG suction
  • Diuretic Therapy
  • Bicarb administration
  • Hyperaldosteronism (Conn’s ↑ Na+, ↓ K+)
59
Q

Treatment for Metabolic Alkalosis?

A
  • Treat the cause!
60
Q

Treatment for Metabolic Alkalosis related to volume depletion.

A
  • Saline fluid resuscitation
61
Q

Treatment for Metabolic Alkalosis related to gastric loss.

A
  • Proton Pump Inhibitors
62
Q

Treatment for Metabolic Alkalosis related to loop diuretics.

A
  • Potassium-sparing diuretics (Spironolactone)

24 ANE 8509 Principles of Anesthesia I (27 decks)

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