Acid-Base Balance - metabolic

Question 1

Acid-Base Regulation

normal: physiological pH: ___ - ___
- < = acidemia
- > = alkalemia

HCO3- = ___ = ___
CO2 = ___ = ___
- compensation for a particular disorder involves the opposite part (lungs compensate metabolix disorder, kidneys compensate respiratory disorders)

Answer 1

7.35-7.45
- kidneys, metabolic
- lungs, respiratory

Question 2

pH of blood determined by ratio of ___ to ___ , not the relative amounts of each

Answer 2

• HCO3-
• pCO2

Question 3

normal blood gas values ( ___ blood)
PaCO2: 35 - 45 mmHg
- remember: ___

HCO3: 22-26 mEq/L
- remember ___

Answer 3

arterial
40
24

Question 4

adverse consequences - acidemia

CV
- ___ CO
- impairment in ___
- ___ pulmonary vascular resistance and arrhythmias

Metabolic
- ___ resistance
- inhibition of anaerobic ___
- ___ kalemia

CNS
- ** ___ or altered mental stauts**

Others:
- decreased ___ muscle strength
- ___ (correct acidosis and blow out CO2)
- dyspnea

Answer 4

CV
- decreased
- contractility
- increased

metabolic
- insulin
- glycolysis
- hyperkalemia

CNS
- coma

others
- respiratory
- hyperventilation

Question 5

adverse consequences - alkalemia

CV
- ___ coronary blood flow due to arterial ___
- ___ anginal threshold
- arrythmias

Metabolic
- ___ K+ , Ca, and Mg
- ___ of anaerobic glycolysis

CNS
- ___ cerebral blood flow
- seizures

others
- decreased ___ (lungs trying to retain as much CO2 as they can)

Answer 5

CV
- decreased, constriction
- decreased

Metabolic
- decreased
- stimulation

CNS
- decreased

Others
- respirations

Question 6

acid generation

1) diet: ~ __ mEqkg/day of acid consumed per day - comes from oxidation of proteins and fats
2) aerobic metabolism of ___ produces 15-20 K mmol of CO2 each day
3) Nonvolatile acids also formed

Answer 6

1
glucose

Question 7

Acid Regulation - 1) buffering

• first line of defense
• buffer: ability of weak acid and its base to resist change in pH with addition of a strong acid or base

prinicple buffer: ___
- ___ onset with intermediate capacity
- HCO3- buffer present in largest [ ]
- how well you can utilize this buffer depends on how well you kidneys and lungs work

when acid is added
- large amount of ___ can be exhaled very rapidly
- body needs new ___ added to system in amount same to H+ loas ingested each day

Answer 7

• bicarbonate
• rapid
• CO2
• HCO3-

Question 8

Acid Regulation - 1) buffering

phosphates
- intermediate onset and capacity ( ___ )
- ___ inorganic phosphated, limited activity
- ___ organic phosphates (more useful)
- Ca Phos in ___ relatively inaccessible (unless long period of acidosis_

Answer 8

• slower
• extracellular
• intracellular
• bone

Question 9

Acid Regulation - 1) buffering

proteins
- ___ / ___ : rapid onset, limited capacity

Answer 9

albumin/hemoglobin

Question 10

Acid Regulation - 2) renal system regulation

kidney serves 2 main purposes:
- reabsord filtered ___
- excrete ___ released from nonvolatile acids

Answer 10

• HCO3-
• H+

Question 11

Acid Regulation - 2) renal system regulation

HCO3- reabsorption
- 4000-4500 mEq of HCO3- is filtered through kidney daily
- 85-90% reabsorbed by ___ tubule
- virtually no HCO3- in ___

Net effect: filtered HCO3- is reabsorbed without any net loss of H+

Answer 11

• proximal
• urine

Question 12

Acid Regulation - 2) renal system regulation

HCO3- reabsorption
anything limiting H+ sectretion into the proximal tubule lumen results in urinary ___ losses

example drug class ___
- decreases entry of ___ and ___
- metabolic ___ occurs with increased HCO3- excretion

Answer 12

• HCO3-
• carbonic anhydrase inhibitors
• CO2, H2O
• acidosis

Question 13

Acid Regulation - 2) renal system regulation

HCO3- generation = ___ excretion
- delayed onset but large capacity (slower)
- reclamation of all filtered HCO3- is not sufficient to maintain normal blood pH
- kidney works hard to excrete huge daily acid load and replete the HCO3- used in the process
- H+ excretion takes place in the ___ tubule

ammonium excretion: ___ mEq/day
titratable acidity: ___ mEq/day

Answer 13

• H+
• distal
• 300
• 30

Question 14

Acid Regulation - 2) renal system regulation

distal tubular H+ secretion
- 50% of net acid axcretion
- CO2 combines with water in the presence of carbonic anhydrase to form H2CO3 -> breaks down to H+ and HCO3-
- the H+ is transported back into the tubular ___ by ATPase
- HCO3- freely crosses the distal tubular membrane and enters the peritubular ___ for absorption

Answer 14

• lumen
• capillary

Question 15

Acid Regulation - 3) ventilatory regulation

• rapid onset and ___ capacity

chemoreceptors detect an increase in PaCO2 and ___ rate/depth of ventilation
- CO2 diffuses easily from tissues to capillary blood to the alveoli

Answer 15

• LARGE
• increase

Question 16

Acid Regulation - 4) Hepatic regulation

• oxidation of proteins generates ___ and ___
• NH4+ can be eliminated via urea synthesis or renal ammoniagenesis
• is liver diminished hepatic urea synthesis, metabolic ___ may occur or an acidotic state will be corrected
• an increase or decrease in the urea cycle will affect the HCO3- pool
• if we dont make urea, we will have more ___ sitting around

Answer 16

• HCO3-, NH4+
• alkalosis
• HCO3-

Question 17

Compensation Chatacteristics for Acid-Base Disorders

1. respiratory compensation very ___
2. renal compensation takes 3-5 ___ for maximum effect
3. compensation moves the pH towards normal, but rarely corrects the pH to normal

Answer 17

• rapid
• days

Question 18

Compensation Chatacteristics for Acid-Base Disorders

metabolic acidosis
- ___ HCO3
- ___ PaCO2

metabolic alkalosis
- ___ HCO3
- ___ PaCO2

respiratory acidosis
- ___ HCO3
- ___ PaCO2

respiratory alkalosis
- ___ HCO3
- ___ PaCO2

Answer 18

metabolic acidosis
- decreased HCO3
- decreased PaCO2

metabolic alkalosis
- increased HCO3
- increased PaCO2

respiratory acidosis
- increased HCO3
- increased PaCO2

respiratory alkalosis
- decreased HCO3
- decreased PaCO2

Question 19

Guidelines for Initial Interpretation of Acid-Base Disorders

metabolic acidosis
- PaCO2 should decrease by ___ times the fall in plamsa HCO3-

when numbers fall outside the above range
- ___ acid base balance
- inadequate extent and/or time for compensation

Answer 19

1.25x
mixed

Question 20

metabolic acidosis

• pH < ___
• low serum HCO3 ( < __ mEq/L)
• compenatory decrease in PaCO2 from ____

classified as either ___or ___
- SAG = _____
- normal: __ - __

Answer 20

• 7.35
• 24
• hyperventilation
• non-anion gap, anion gap
• SAG = Na - (Cl + HCO3)

Question 21

Metabolic acidosis - patho of non-anion gap (hyperchloremic acidosis)

• overall, there is a loss of plasma ___ replaced by ___

Causes
GI HCO3- loss: ___ , pancreatic fistulas/biliary drainage

renal HCO3- loss: type II renal tubular acidosis (proximal):
- ___ , topiramate, HIV
- reabsorption threshold for HCO3 decreased in proximal tubule
- loss of HCO3 -> loss of ___ -> loss of ___ -> activate ___ -> secondary ___
- leads to hypo ___

Answer 21

• HCO3
• Cl
• diarrhea
• CAIs
• Na, fluid, RAAS, hyperaldosteronism
• hypokalemia

Question 22

Metabolic acidosis - patho of non-anion gap (hyperchloremic acidosis)

Causes (cont):
reduced renal H+ excretion (distal tubule RTAs)

Type I RTA ( ___ RTA)
- H+ cannot be pumped into tubule lumen
- urine cant be maximally acidified
- increase in ___ excretion

Type IV RTA (hypoaldosteronism or ___ RTA)
- less aldosterone and hyperkalemia = H+ ___ = acidosis

chronic renal failure
- ___ H+ secretion
- less ___ production

Answer 22

• hypokalemia
• K+
• hyperkalemia
• retention
• decreased
• ammonia

Question 23

Metabolic acidosis - patho of non-anion gap (hyperchloremic acidosis)

Causes (cont)
___ and ___ administration
- TPN administration
- HCl or ammonium Cl adminitrations

Answer 23

acid, chloride

Question 24

Metabolic acidosis - patho of anion gap

MULEPAK

Answer 24

Methanol intoxication
Uremia
Lactic acidosis
Ethylene glycol
Paraldehyde ingestion
Aspirin (salicylates)
Ketoacidosis

Question 25

# Metabolic acidosis - patho of anion gap MUDPILES

Answer 25

Methanol intoxication Uremia Diabetic ketoacidosis Poisoning/propylene glycol ingestion Intoxication/infection Lactive acidosis Ethylene glycol Salicylate/sepsis

Question 26

# Metabolic acidosis - patho of anion gap Overall ___ losses are replaced with another anion besides Cl Delta Gap = ____ - when delta added to patient's measured HCO3, result should be in normal HCO3 range - if elevated, indicates metabolic ___ in addition to acidosis, (mixed)

Answer 26

- HCO3 - pt's anion gap - 10 - alkalosis

Question 27

# Causes of Anion Gap Metabolic Aciosis ___ acidosis (most common cause) - lactate is a normal product of anaerobic metabolism (pyruvate -> lactate) - lactate formation essential for RBCs and exercising muscle - increased levels always result from decreased clearance versus overproduction - HCO3- buffers lactate - persistent failure to oxizide will exhause buffer

Answer 27

lactic

Question 28

# causes of lactic acidosis 1) ___ 2) drugs/toxins: alcohol, ___ , propylene glycol 3) ___ - self limiting 4) ___ : packed poorly perfused bone marrow cavities 5) hepatic/renal failure 6) ___ : formation of ketones/lactate 7) malnutrition: deficiencies of vitamins and thiamine 8) rhabdomyolysis

Answer 28

- shock - metformin - seizures - leukemia - diabetes mellitus

Question 29

# Causes of Anion Gap Metabolic Aciosis (cont) Ketoacidosis - increase in acetoacetic acid Drug intoxications: ___ toxicity - respiratory ___ - stimulation of respiratory drive - metabolic ___ - also methanol/ethylene glycol ingestion

Answer 29

- salicylate - alkalosis - acidosis

Question 30

# Symptoms of lactic acidosis - Kussmauls ___ (compensation) - peripheral ___ causing flushing and tachycardia; as acidosis worsens, ventricular arrhythmias or reduced contractilty may occur - ___ kalemia - lethargy/coma - nausea/vomiting - ___ demineralization in chronic acidotic states

Answer 30

- respirations - vasodilation - hyperkalemia - bone

Question 31

# Anion Gap metabolic acidosis treatment treat underlying cause acute ___ therapy (for severe and acute bicarb losses) - consider use if pH < ___ Dose (mEq) = ___ - use ___ for desired HCO3 - give ___ - ___ the calculated dose - during cardiac arrests ~1 mEq/kg may be given - supplement ___ if needed

Answer 31

- HCO3 - 7.1 - Dose (mEq) = (0.5 x IBW) x (desired HCO3 - actual HCO3) - 12 - 1/3 - 1/2 - K

Question 32

# Hazards of HCO3 therapy - overalkanization can reduce cerebral flow and can impair oxygen ___ from Hgb to tissues (shift to left) - ___ /hyperosmolality - CSF ___ accurs from the CO2 that is generated, which readily diffuses into the CSF electrolyte shifts - K sucked back into cells = ___ - decreased ionized Ca = decreased myocardial contractility

Answer 32

- release - hypernatremia - acidosis - hypokalemia

Question 33

chronic bicarb therapy for chronic metabolic acidosis - average dose: __ - __ mEq/kg/day (may go up to 10+ mEq/kg/day)

Answer 33

1-3

Question 34

# Metabolic alkalosis - increased pH (> ___ ) - increased HCO3 ( > __ mEq/L), and a compensatory ____ resulting in increased PaCO2

Answer 34

- 7.45 - 30 - hypoventilation

Question 35

# Metabolic alkalosis patho 3 mechanisms 1. loss fo acid from ___ or ___ 2. administration of HCO3 or bicarb precursor 3. contraction alkalosis often, ___ and ___ depletion contribute

Answer 35

- GI, urine - volume, Cl

Question 36

# Metabolic alkalosis - saline responsive saline responsive - urinary chloride < ___ - ___ mEq/L hypochloremic state - normally, Cl- is anion absorbed with Na - without Cl, Na is reabsorbed with ___ causes - ___ therapy - ___ and NG suction - exogenous HCO3 administration or ___ transfusion

Answer 36

- 10-20 - HCO3 - diuretic - vomiting - blood

Question 37

# Metabolic alkalosis - saline resistant saline resistant urinary chloride > ___ mEq/L - key difference: no ___ depletion causes - increased ___ activity - hypokalemia - renal tubular ___ wasting Increased aldosterone = H+ ___ and ___

Answer 37

- 20 - Cl - mineralcorticoid - chloride - secretion, hypokalemia

Question 38

# Metabolic alkalosis symptoms - muscle ___ ; weakness; parathesias - postural dizziness - cellular hypoxia, mental ___ , coma, seizures - diect ___ suppression; CV collapse; arrhythmias

Answer 38

- cramps - confusion - myocardial

Question 39

# Metabolic alkalosis - treatment - correct underlying cause - rapid correction not necessary but treatment still needed saline responsive - fluid/electrolyte replacement with ___ or ___ - use caution with HF, hepati/renal failure patients Ex. NS with 20-40 mEq/L KCl over 4-5 hours then NS with 20-40 mEq/L KCl at 125-200 mL/hr - may also used LRs for certain patients - but lactate will be come HCO3 so be careful ___ ___ inhibitors - cause acidosis (good for correcting) - helpful in patients who cannot tolerate excess fluids/Na - ___ wasting; supplement - not helpful in volume depletion, renal dysfunction, or severe alkalosis alternatives for persistent metabolic alkalosis - ___ acid in D5W or NS - monitoring: ABG and K+ at least q4h during infusion - ammonium chloride - monitoring: ABG every 4 hrs; mental status; electrolytes adjunct therapy: ___ or ___ in patients with vomiting or NG suctions

Answer 39

- NaCl or KCl - carbonic anhydrase - K - HCl - H2RA, PPIs

Question 40

# Metabolic alkalosis treatment - saline resistant alkalosis saline resistant - correct ___ with K sparking diuretic or KCl supplementation - decrease dose of ___ or change steroids to one with less activity - administer ___ - antagonizes mineralcorticoid receptor (inhibits aldosterone stimulation of H+ ___ ) - correct ___ - give fluids

Answer 40

- hyokalemia - mineralcorticoid - spironolactone, secretion - hyperaldosteronism