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Mar: Sem 3 - Principles I (Full) > Exam 2 Acid-Base Disorders [6/17/24] > Flashcards

Exam 2 Acid-Base Disorders [6/17/24] 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

slide 2

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2
Q

Change in relative concentrations of ____ and ____ change water ability to auto-ionize.
What is the purpose of this?

A
  • fluid and electrolytes [Na, K, bicarb, H2O]
  • ensures optimal enzymatic function

slide 2

1831 O’Shuaghnessy “loss of carbonate of soda” in cholera patients.

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3
Q

Define acidemia

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

S3

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4
Q

Define alkalemia.

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

S3

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5
Q

How is pH measured?

A
  • Measured as H+ concentration pH
  • The Power of Hydrogen

S4

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6
Q
  • The stability of pH is managed by what three factors?
  • How do they enter and leave the body?
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)

S5

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7
Q

What is the equation to calculate pH?
What is this equation called?

A
  • pH = 6.1 + log [serum bicarb/(0.03 x PaCO2)]
  • Henderson- Hasselbalch equation

coined acid-base balance

S5

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8
Q

water is amphoteric meaning what?

A
  • it can act as either an acid or a base
  • HCl [acid] donates a proton to water [base]
  • KOH [base] receives a proton from water [acid]

S6

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9
Q
  • How do we determine the strength of an acid or base?
  • what is an example of a strong acid?
  • what is an example of a weak acid?
A
  • degree of dissociation in water determines strength
    • lactic acid [pka 3.4] completely dissociates in water–> strong acid
    • carbonic acid [pka 6.4] incompletely dissociates in water –> weak acid

S6

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10
Q

What are the 3 rules for acid base?

A
  1. electrical neutrality: of the negative and positively charged ions
    • when we add all the cation and anions it should be equal
  2. dissociation equilibria: the propensity to dissociate
    • chunk of a substance put in water wants to break off into little pieces. Its tendency is to not stay as one solid
  3. mass conservation: the amount of substance remains constant
    • not insize, but in amount

S7

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11
Q

What are the characteristics of strong Ions?
* dissociation?
* most abundant in ECF?
* others strong ions?

A
  • dissociate completely
  • Most abundant ECF strong ions: Na+ & Cl-
  • others: K+, SO42-, Mg2+, Ca2+

S8

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12
Q
  • What is the formula for strong Ion difference [SID]?
  • In ECF, is the SID + or -?
  • SID is an independent predictor of?
A
  • Total strong cations- Strong anions
  • in ECF SID alway positvie
  • an independent predictor of pH

S8

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13
Q

How do you identify a pH disturbance?

A
  1. is ph increased or decreased?
  2. is PaCO2 and/or HCO3- increased or decreased from normal?

S9

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14
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

S9

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15
Q

How can you tell if an acid-base disorder is a mixed acid/base problem?

A
  • PaCO2 and HCO3 are in different directions.

S9

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16
Q

What are normal values for:
* pH:
* PCO2:
* HCO3:

A
  • pH: 7.35-7.45 [7.4]
  • PCO2: 35-45 [40]
  • HCO3: 22-28 [24]

S10

number in brackets is average number to use

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17
Q

What is the Acid/Base Disorder
pH: 7.33
PCO2: 48
HCO3: 26

A

RR acidosis with partial compensation
- pH: low
- PCO2: high
- HCO2:Normal

S10

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18
Q

What is the Acid/Base Disorder
pH: 7.58
PCO2: 35
HCO3: 29

A

metabolic alkalosis
- pH: high
- PCO2: normal
- HCO2: high

S10

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19
Q

What is the Acid/Base Disorder
pH: 7.28
PCO2: 46
HCO3: 18

A

Mixed RR and metabolic acidosis

S10

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20
Q

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

A

RR alkalosis with partial compensation

S10

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21
Q

What are CV concesquences of acidosis?

A
  • impaired contractility [7.2]
  • decreased arterial blood pressure
  • sensitive to re-entry dyshythmias
  • decreased threshold for v-fib
  • decreased responsivness to catecholamines [7.1]

IS DDD

S11

7.2 and 7.1 is the pH at which this occur

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22
Q

What are nervous system consequences of acidosis?

A
  • obtundation →
  • coma

S12

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23
Q

what are pulmonary consequences of acidosis?

A
  • hyperventilation [to blow off CO2]
  • dyspnea
  • respiratory muscle fatigue

S13

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24
Q

what are metabolism consequences of acidosis?

A
  • hyperkalmeia
  • insulin resisance
  • inhibition of anaerobic glycolysis

S14

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25
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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26
Q

Define Respiratory Acidosis

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

S15

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27
Q

What are the causes of Respiratory Acidosis?

A
  • Causes:
    • Drug-induced ventilatory depression [prop, fent, NMBD, versed]
    • Malignant hyperthermia
    • inadequate NMBD reversal
    • Disorder of neuromuscular function
    • Status asthmaticus
    • Upper airway obstruction
    • Permissive hypercapnia [improper vent settings]
    • PNA/ Pulmonary Edema, Pleural Effusion
    • Restriction of ventilation (rib fx, flail chest)
    • opioid excess
    • CO2 insufflation

PPROUDD MISC
Drugs MID SUPPR-OC cause respiratory acidosis

S15

Causes Can be split into these categories:
* Central Ventilation Control
* Peripheral Ventilation Control
* VQ mismatch [airway problem]
categories is on another card, just here as a reminder

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28
Q

When does CO2 insufflation occur and how do you fix it?

A

in laparoscopic cases. The CO2 will need to be blown off the lungs, so adjust vent settings to help blow off CO2

S15- lecture

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29
Q

⭐️What are the three categories that can cause Respiratory Acidosis?

A
  • Central ventilation control (neuro/brain)
  • Peripheral ventilation control (neuromuscular disease)
  • V/Q Mismatch [Airway problem]

S16

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30
Q

⭐️Slow shallow breathing is related to a central problem.
* What is this associated with?
* What is this due to?

A
  • usually associated with somnolence
  • D/T:
    • residual opioids
    • benzos
    • propofol

S16

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31
Q

⭐️rapid shallow breathing is related to a peripheral problem which is d/t what 3 main things?

A
  • Neuromuscular
    • residual NM blockade
    • high epidural/spinal
  • Throacic
    • pneumothorax
    • hemothorax
  • V/Q mismatch
    • abdominal splinting
    • retained secretion
    • atelactasis

S16

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32
Q

⭐️obstructed breating is related to an airway problem which is d/t?

A
  • Airway obstruction
    • supraglottic
    • glottic
    • subglottic
    • bronchospasm

S16

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33
Q

Acute Hypercarbia Compensation

  • With acute hypercarbia, how long does it take for the bicarb to compensate for the acid-base disorder?
  • For compensation to occur in acute hypercarbia, an increase in PaCO2 of 10mmhg should increase the HCO3 by how much?
A
  • Very slowly (2-3 days)
  • Increase in 1 mEq/L of HCO3 for every 10 mmHg of PaCO2

S17

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34
Q

Chronic Hypercarbia

For compensation to occur in chronic hypercarbia, an increase in PaCO2 of 10mmhg should increase the HCO3 by how much?

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

S17

This is prevalent in COPD patients

35
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
  • Normal PaCO2 level: 40 mmHg
  • Normal HCO3 level: 24 mEq/L
  • PaCO2 increased by 40 mmHg
  • For acute hypercapnia, ↑PaCO2 of 10 mmHg=↑HCO3- of 1 mEq

Answer: 28meq/L

S18

36
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
  • Normal PaCO2 level: 40 mmHg
  • Normal HCO3 level: 24 mEq/L
  • PaCO2 increased by 40 mmHg
  • Chronic Hypercapnia: ↑PaCO2 10 mmHg=↑HCO3- 3 mEq
    • HCO3- increase by 12 mEq/L

Answer: 36 mEq/L

S18

37
Q

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

Narcosis: a state of stupor, drowsiness, or unconsciousness produced by drugs.

A
  • Mechanical Ventilation
  • Increase minute ventilation by ↑ tidal volume, ↑ respiratory rate, or both.

S19

38
Q

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

A
  • Excessive bicarb will cause CNS irritability leading to seizures

S19

39
Q
  • when should you be cautious when giving bicarb?
  • when can you give bicarb?
A
  • Bicarb should not be 1st line of tx if pt has:
    • RR acidosis w/ metabolic compensation [high bicarb level]
    • Mixed Acidosis
  • Bicarb can be given
    • when there is data that proves it’s metabolic acidosis.

S19 - lecture

40
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)

S20

Respiratory compensation does not fully counter excessive acid production

41
Q

What are causes of metabolic acidosis?

A
  • increased production of acid
  • decreased excretion of acid
  • acid ingestion
  • renal/GI bicarbonate losses

S20

42
Q

What 3 things is metabolic acidosis associated with?

A
  • alteraration in transcellular ion pumps
  • ↑ ionized calcium
  • right shift of oxyhgb curve

S20

43
Q

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

A
  • Rightward Shift [decreased affinity for O2]
  • This will allow O2 to be released and available to the tissues
    *

S20

44
Q

What is the formula to determine if the body is compensating for acute metabolic acidosis?

A
  • (1.5 x HCO3) + 8
    or
  • for evey 1 mEq/L ↓ in BE, PaCO2 should fall 1.2 mmhg
45
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

S21

46
Q

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

A
  • 1.2 mmHg
    otherwise compensation is inadequate

S21

47
Q

normal anion gap

  • A normal anion gap maintains __________.
A
  • Electrical neutrality
    • Na balanced by sum of bicarb and chloride.

S22

48
Q

normal anion gap

Bicarb loss is countered by?
What is this called?

A
  • Bicarb loss is countered by net gain of chloride ions
  • This is often called hyperchloremic acidosis

S22

49
Q

Factors that cause metabolic acidosis with a normal anion gap.

A
  • Sodium Chloride Infusion
  • Diarrhea
  • Early Renal Failure

S22

50
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

S23

51
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

S23

52
Q
  • What does the anion gap underestimate?
  • What is it complicated by?
A
  • frequently underestimates extent of disturbance
  • complicated by hypoalbuminemia, hypophosphatemia

S23

53
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
    • Anion Gap >20

S24

54
Q

Causes of high anion gap.

A
  • Lactic Acidosis
  • Ketoacidosis
  • Renal Failure
  • Poisoning

S24

55
Q

Mnemonic for anion gap acidosis

A
  • C: cyanide and CO
  • A: arsenic
  • T: toluene
  • M: methanol, metformin
  • U: uremia
  • D: DKA
  • P: paraldehyde
  • I: iron
  • L: lactate
  • E: ethylene glycol
  • S: salicylates

S25

56
Q

What is lactic acidosis?

A
  • Marker of critical ilnnes
    • over production vs inadequate clearance of lactic acid
    • presistent acidosis

S26

57
Q

where does lactic acid come from?

A
  • degradation product of glucose metabolism
    • excess catecholamines degrades to lactacte –> pyruvate –> gluconeogeniss [produce more sugar for energy]
      • anerobic
      • aerobic
    • buffer in isotonic solutions

S26

58
Q

⭐️Decision tree for lactic acidosis

A

LOOK AT
1. What is the lactate level? What is the pH?
2. how is the heart ? [CO, SV, CVP, SVO2?]
3. Low or normal
4. Diagnosis

S27

59
Q

How do you treat metabolic acidosis?

A
  • Treat the cause!

S28

60
Q

Treatment for Metabolic Acidosis related to Ketoacidosis.

A
  • Insulin
  • fluids

S28

61
Q

Treatment for Metabolic Acidosis related to Lactic Acidosis.

A
  • Improve tissue perfusion
  • fluid resuscitate
  • discontinue metformin

S28

62
Q

Treatment for Metabolic Acidosis related to Renal Failure.

A
  • Dialysis

S28

63
Q

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

A
  • pH < 7.1
  • HCO3- < 10 mEq/L

very controversial bc we dont want a metabolic alkalosis shift

S29

64
Q

What are the 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 of ocyhemoglobin curve (Bohr effect) and cause tissue hypoxia

S29

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

65
Q

What is the formula for a full correction dose of bicarb?

A
  • Full correction dose(mmol)
    • 0.3 x Base Deficit (mmol/L) xWt(kg)
  • Give half this dose and reassess

S29

66
Q

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

A
  • Surgery will be postponed

S30

67
Q

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

A
  • Hemodynamic monitoring [Swann, SVV line, Art Line]
  • Give Fluids
  • Monitor Cardiac Functions
  • Frequent Lab
  • Uphill battle, be honest with family members

S30

68
Q

Define Respiratory Alkalosis.

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

S31

69
Q

What are the causes of Respiratory Alkalosis?

A
  • Pregnancy
  • High Altitude (↑RR)
  • Salicylate overdose (asprin)
  • Iatrogenic hyperventilation (during perioperative period/ fear)
    I SHIP the causes of respiratory alkalosis

S31

70
Q

What are the symptoms of Respiratory Alkalosis?

A
  • Decrease PaCO2 will cause vasoconstriction:
    • Lightheadedness
    • Visual disturbance
    • Dizziness

S32

71
Q

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

A
  • Albumin

Patient will be hypocalcemic.

S32

72
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)

S32

73
Q

How many branches of the facial nerve are there?

Name them :)

A

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

additional info

Two Zebras Bit My Chicken

74
Q

Anesthesia management of respiratory alkalosis.

A
  • Consider what is causing the hyperventilation (anxiety, pain, full bladder, agitation)
  • Poor mechanical ventilation strategy
  • Therapeutic Hyperventilation

S33

75
Q

Define Metabolic Alkalosis.

A
  • Marked increase in plasma bicarb usually compensated by an increase in CO2

S34

76
Q

Metabolic Alkalosis is usually ____ and has ____ or ____ causes from what?

A
  • Usually iatrogeninic: Renal or extrarenal causes
    • Net loss of H+ or a net gain of bicarb
    • excess citrate

S34

77
Q

What are other names for Metabolic Alkalosis?

A
  • Volume depletion alkalosis
  • Volume overload alkalosis

S34

78
Q

What are the causes of Metabolic Alkalosis?

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

High Bicarb Has Very Nasty Damage

S35

79
Q

What are the symptoms of metabolic alkalosis?

A
  • lightheadnedness
  • tetany
  • paresthesia

**also due to hypocalcemia [like RR alkalosis]

S35

80
Q

Treatment for Metabolic Alkalosis?

A
  • Treat the cause!

S36

81
Q

Treatment for Metabolic Alkalosis related to volume depletion.

A
  • Saline fluid resuscitation

S36

82
Q

Treatment for Metabolic Alkalosis related to gastric loss.

A
  • Proton Pump Inhibitors

S36

83
Q

Treatment for Metabolic Alkalosis related to loop diuretics.

A
  • Potassium-sparing diuretics (Spironolactone)

S36

Mar: Sem 3 - Principles I (Full) (29 decks)

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