Principles I* > E2- ABGs > Flashcards

E2- ABGs Flashcards

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1
Q
  • In order to ensure optimal function of __________ function, acid-base balance is tightly regulated at what pH?
  • changes in [] of F/E - changes waters ability to ____?
  • 1831 = O’Shaughness discovrered ?? in what pts?
A
  • enzymatic
  • 7.35 to 7.45
  • auto-ionize
  • loss of carbonate of soda in CHOLERA pts
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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)

OH = hydroxyl 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 3 factors?

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

What is the equation to calculate “acid-base balance”?

A

Henderson-Hasselbalch equation

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

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7
Q
  • Water can be acid or base + is considered ______?
  • _____ is a strong acid that _______ proton w/ water
  • _____ is a strong base that ______ proton w/ water
A
  • amphoteric
  • HCl - donates to water
  • KOH - receives from water
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8
Q
  • Degree of dissociaition in water determines what?
  • _____ has a pKa of 3.4 ,, completely dissociates = strong acid
  • ______ has a pKa of 6.4 ,, partially dissociates = weak acide
A
  • strength
  • lactic acid
  • carbonic acid
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9
Q

3 rules

Describe Electrical Neutrality

A

o Add all positive + negative charges – should be EQUAL to each other

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10
Q

3 rules

Describe Dissociation Equilibria

A

o The propensity of substance to dissociate
o Put chunk of substance into water + it wants to break up

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11
Q

3 rules

Describe Mass Conservation

A

o The amount of substance remains constant
o Not in size ,, but amount
o Cannot create or lose substance unless another process interfering

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12
Q

What is the most abundant ECF strong cation + anion?
Other ones?

A

**Na+, Cl- **

K+, SO42-, Mg2+, Ca2+

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13
Q
  • Thestrong ion difference is the ability of ECF to maintain a more _______ environment.
  • It is an __________ predictor of pH
  • Equation?
A
  • positive
  • independent
  • total = strong cations - strong anions
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14
Q
  • acid-base disorder= primary disorder with secondary compensation?
  • acid-base disorder = mixed acid/base problem?
A
  • Both PaCO2 + HCO3 change in same direction
  • PaCO2 + HCO3 in different directions
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15
Q

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

A

Uncompensated Respiratory Acidosis

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16
Q

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

A

Uncompensated Metabolic Alkalosis

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17
Q

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

A

MIXED met/resp acidsois

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18
Q

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

A

Uncompensated Respiratory Alkalosis
probs starting to compensate

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19
Q

5 Cardiovascular Consequences of Acidosis

A
  • Impaired contractility = pH 7.2
  • Decreased arterial bp
  • Sensitive to re-entry dysrhythmias
  • Decrease threshold for V-fib
  • Decreased responsiveness to catecholamines = pH 7.1

CBD is VC (very cool)

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20
Q

2 Nervous System Consequence of Acidosis

A
  • Obtundation
  • Coma
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21
Q

3 Pulmonary Consequences of Acidosis

A
  • Hyperventilation (d/t compensation, blowing off CO2)
  • Dyspnea
  • Respiratory Muscle Fatigue
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22
Q

3 Metabolism Consequence of Acidosis

A
  • Hyperkalemia (contributes to reentry dysrhythmias)
  • Insulin Resistance
  • Inhibition of anaerobic glycolysis
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23
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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24
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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25
How do we cause Resp Acidosis?
inadequate NMBD reversal opioid excess CO2 insufflation
26
What are the 3 categories that can cause Respiratory Acidosis?
* **Central** ventilation control (neuro/brain) * **Peripheral** ventilation control (neuromuscular disease) * **VQ** mismatch (Pneumonia)
27
ACUTE hypercarbia, how long does it take for the bicarb to compensate for the acid-base disorder? PaCO2 increases by 10 mmHg = increase _______ mEq/L of HCO3- for system to be compensated
* Very **slowly** (2-3 days) * Increase in **1 mEq/L **of HCO3 for every 10 mmHg of PaCO2 | *COPD from 40 > 50 ,, Bicarb from 24 >25*
28
How much will HCO3- increase with compensated CHRONIC hypercarbia?
* ↑ PaCO2 of **10 mmHg **= ↑ HCO3- by **3 mEq/L** ## Footnote This is prevalent in COPD patients
29
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?
*** 28 mEq/L** Normal PaCO2 : 40 mmHg Normal HCO3 : 24 mEq/L PaCO2 = =80 mmHg PaCO2 **increased by 40 mmHg ** For **acute** hypercapnia, every 10 mmHg PaCO2 = ↑HCO3 by 1 mEq ---- increase by 4 Below 28 = add aggressive treatment bc body not compensate
30
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?
*** 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**
31
What would be the treatment for respiratory acidosis :: if hypercarbia is marked + CO2 narcosis is present?
* Mechanical Ventilation
32
Why should there be caution with chronic hypercarbia reversal with bicarb?
* Excessive bicarb will cause CNS irritability >> seizures
33
Define Metabolic Acidosis.
* A lowered blood pH - stimulates respiratory center to hyperventilate * Metabolic Acidosis is secondary to an underlying disorder (fix the problem to fix acidosis) ## Footnote **Respiratory compensation does not fully counter excessive acid production**
34
Metabolic Acidosis is associated with alterations in transcellular ____________ and ↑ ionized calcium.
* ion pumps
35
What direction will the Oxygen-Hemoglobin Dissociation Curve shift with Metabolic Acidosis?
* Rightward Shift * This will allow O2 to be released and available to the tissues
36
What is your expected PaCO2 if your HCO3- is 12 mEq/L?
* PaCO2 = 26 mmHg * If PaCO2 is **HIGHER** 26 mmHg, compensation is **INADEQUATE** **PaCO2 = (1.5 x HCO3-) + 8 ** = (1.5 x 12) + 8 = 26 mmHg
37
For every 1 mEq/L of negative base excess, PaCO2 should fall ______ mmHg.
* **1.2 mmHg** * otherwise inadequate compensation
38
A normal anion gap maintains __________.
* Electrical neutrality
39
Bicarb loss is countered by the net gain of ______ ions. Often called ?
* Chloride ions * often called hyperchloremic metabolic acidosis
40
3 cause metabolic acidosis + **normal** anion gap.
* Sodium Chloride Infusion * Diarrhea * Early Renal Failure *Sure dad extra little kidneys really poop (suck)*
41
What defines a high anion gap?
* > 20 mEq/L * Additional acid that is added to **extracellular** space * Acids dissociates into H+ - combine with bicarb - form carbonic acid - decrease available bicarb
42
4 Causes of high anion gap.
* Lactic Acidosis * Ketoacidosis * Renal Failure * Poisoning *Sure dad extra little kidneys really poop (suck)*
43
Mneumonic for High Anion Gap Acidosis
*** CAT MUDPILES** * C: Cyanide + CO * A: Arsenic * T: Toluene * M: Methanol + Metformin * U: Uremia * D: DKA * P: Paraldehyde * I: Iron * L: Lactate * E: Ethylene glycol * S: Salicylates
44
What is the simple anion gap formula? What is the range of a simple anion gap?
* Sodium - (Chloride + Bicarb) * 12-14 mEq/L
45
What is the conventional anion gap formula? What is the range of a conventional anion gap?
* (Sodium + Potassium) - (Chloride + Bicarb) * 14-18 mEq/L
46
Anion Gap frequently ___________ (overestimates/underestimates) the extent of acid-base disturbances.
* Underestimates * complicated by hypo-albumin ,, hypo-phosphate ## Footnote This is complicated by hypoalbuminemia and hypophosphatemia
47
Lactic Acidosis
48
How do you treat metabolic acidosis?
* Treat the cause!
49
Treatment for Metabolic Acidosis related to Ketoacidosis.
* Insulin and fluids
50
Treatment for Metabolic Acidosis related to Lactic Acidosis.
* Improve tissue perfusion * Dc **Metformin** * fluids
51
Treatment for Metabolic Acidosis related to Renal Failure.
* Dialysis
52
What are the parameters to treat metabolic acidosis with sodium bicarbonate?
* pH **< 7.1 ** * HCO3- **< 10 mEq/L**
53
What are the negative effects of administering bicarb to someone with metabolic acidosis?
* 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 ## Footnote The administration of IV NaHCO3 to treat metabolic acidosis should be reserved for the emergency treatment of select conditions
54
Formula for HCO3- Correction Dose
* Dose of Bicarb = **0.3 x Base Deficit x Wt (kg)** * Give 1/2 dose ## Footnote Oftentimes, you would give half this dose and reassess
55
2 reasons treat with bicrb is controversial?
1. **reacts with H** to decrease pH more 2. in **chronic met. acidsosis** - pH change negates Rigth shit + can't get oxygen to tissue
56
What happens to elective surgery if the patient experience acute metabolic acidosis?
* Surgery will be postponed
57
Anesthesia management considerations for urgent/emergent surgery with metabolic acidosis.
* Hemodynamic monitoring * Give Fluids * Monitor Cardiac Functions * Frequent Lab - POCUS q30 min
58
Define Respiratory Alkalosis.
* An acute increased alveolar ventilation * Results in ↓ PaCO2 and pH > 7.45
59
What are 5 causes of Respiratory Alkalosis?
* Anxiety * Pregnancy * High Altitude (↑RR) * Salicylate overdose (asprin) * Iatrogenic hyperventilation (during perioperative period/ fear)
60
* What does decrease PaCO2 cause? * What are the symptoms of Respiratory Alkalosis?
* Decrease PaCO2 will cause **vasoconstriction** * Lightheadedness * Visual disturbance * Dizziness
61
Respiratory Alkalosis will result in greater binding of calcium to ________.
* Albumin *Patient will be hypocalcemic.*
62
What are the signs and symptoms of hypocalcemia?
* Paresthesia, muscle spasm, cramp, tetany, circumoral numbness, seizures * Trousseau's sign * Chvostek's sign (Irritability on the facial nerve)
63
Anesthesia management of respiratory alkalosis.
* Consider what is causing the hyperventilation (anxiety) * Consequence of Pain, Full Bladder, Agitation * Poor **mechanical ventilation** strategy * Therapeutic Hyperventilation
64
Define Metabolic Alkalosis.
* 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 * excess **citrate**
65
What are other names for Metabolic Alkalosis?
*** Volume depletion** alkalosis * **Volume overload **alkalosis
66
What are 6 causes of Metabolic Alkalosis?
* getting rid of acid ! * Hypovolemia * Vomiting * **NG suction** * **Diuretic Therapy** * Bicarb administration * **Hyperaldosteronism** (Conn's ↑ Na+, ↓ K+)
67
Symptoms of metabolic alkalosis?
d/t calcium imbalance o Lightheadedness, tetany, paresthesia
68
Treatment for Metabolic Alkalosis?
* Treat the cause!
69
Treatment for Metabolic Alkalosis related to volume depletion.
* Saline fluid resuscitation
70
Treatment for Metabolic Alkalosis related to gastric loss.
* Proton Pump Inhibitors
71
Treatment for Metabolic Alkalosis related to loop diuretics.
* Potassium-sparing diuretics (Spironolactone)

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