acid base

Question 1

what is a normal pH?

Answer 1

7.4 (7.35-7.45)

Question 2

how is pH regulated?

Answer 2

buffers (bicarbonate and carbon dioxide)
respiration (lungs)
metabolic (kidneys)

Question 3

lower pH= more _____ (acidic/basic)

Answer 3

acidic

Question 4

pH is the inverse of ___

Answer 4

how much acid (-log H)

Question 5

definition of an acid

Answer 5

H+ donor

Question 6

CO2 is ____

Answer 6

acid

Question 7

definition of a base

Answer 7

H+ acceptor

Question 8

HCO3- is ___

Answer 8

base

Question 9

definition of buffer

Answer 9

ability of a weak acid + anion (base) conjugate pair to resist pH changes after the addition of a strong acid or base

Question 10

role of carbonic anhydrase

Answer 10

enzyme that converts CO2 to carbonic acid

Question 11

“emia” refers to

Answer 11

objective sign in the blood
(abnormal pH)

Question 12

“osis” refers to

Answer 12

the disease process
(metabolic or respiratory process led to abnormal pH)

Question 13

normal PaCO2

Answer 13

35-45

Question 14

normal HCO3-

Answer 14

22-26

Question 15

how is arterial blood gas documented

Answer 15

pH/PaCO2/PO2/HCO3/SaO2

Question 16

disorder when pH < 7.35

Answer 16

acidemia

Question 17

disorder when pH > 7.45

Answer 17

alkalemia

Question 18

disorder when PCO2 < 35

Answer 18

respiratory alkalosis

Question 19

disorder when PCO2 > 45

Answer 19

respiratory acidosis

Question 20

disorder when HCO3- < 22

Answer 20

metabolic acidosis

Question 21

disorder when HCO3 > 26

Answer 21

metabolic alkalosis

Question 22

how do the lungs try to regulate pH?

Answer 22

they either “blow off” or retain CO2 by altering minute ventilation

Question 23

how do the kidneys try to regulate pH?

Answer 23

they either increase or decrease reabsorption of HCO3-

Question 24

how will the lungs try to compensate in metabolic alkalosis?

Answer 24

try to retain CO2 by decreasing minute ventilation to decrease the pH

Question 25

how will the lungs try to compensate in metabolic acidosis?

Answer 25

try to blow off CO2 by increasing minute ventilation to increase the pH

Question 26

how will the kidneys compensate for respiratory alkalosis?

Answer 26

try to absorb less bicarb to decrease the pH

Question 27

how will the kidneys compensate for respiratory acidosis?

Answer 27

try to retain bicarb to increase the pH

Question 28

what is anion gap

Answer 28

calculation used to find causes of metabolic acidosis Na - (HCO3 + Cl) normal range is 4-12 adjust for albumin: add 2.5 to gap for every 1g/dL of albumin below 4

Question 29

what if anion gap >12?

Answer 29

MUDPILES Methanol Uremia Diabetic ketoacidosis Propylene glycol Ingestion Lactic acidosis Ethylene glycol Salicylates

Question 30

what if anion gap normal?

Answer 30

USEDCAR Ureteral diversion Saline infusion Exogenous acid Diarrhea Carbonic anhydrase inhibitors Adrenal insufficiency Renal tubular acidosis

Question 31

what are some signs of respiratory acidosis?

Answer 31

pH < 7.35 CO2 > 45 decreased respiratory rate (retaining acid) altered mental status, tachycardia

Question 32

how to treat respiratory acidosis?

Answer 32

mechanical ventilation: make them breathe (hyperventilate them to get them to blow off CO2) treat underlying cause (opiate antagonist, bronchodilators, etc)

Question 33

objective signs of metabolic acidosis

Answer 33

pH < 7.35 HCO3 < 22 hyperventilation (from lungs trying to compensate) +/- elevated anion gap (MUDPILES if elevated, USEDCAR if normal)

Question 34

what are some potential causes of lactic acidosis?

Answer 34

increased oxygen demand (extreme exercise or seizures) decreased oxygen delivery (hypotension, severe anemia, severe HF) drugs (metformin and salicylates) decreased lactate clearance (hypoperfusion, liver failure) toxins (methanol, ethanol)

Question 35

treatment of metabolic acidosis

Answer 35

1. correct the underlying cause (whether that is gap or non gap. examples: give antidote, give insulin, dialysis) 2. give some base: IV sodium bicarbonate in SEVERE cases when pH <7.15

Question 36

IV sodium bicarbonate dosing?

Answer 36

(0.5 L/kg x IBW) x (desired bicarb- actual bicarb) administer 1/2 dose stat push, then give the rest over 4-6 hours

Question 37

when to give oral bicarb?

Answer 37

in mild case of metabolic acidosis where pH is 7.2-7.4

Question 38

signs of respiratory alkalosis

Answer 38

pH > 7.45 CO2 < 35 respiratory rate increased (from blowing off CO2) can happen from altitude, setting mechanical ventilation too fast, hyperventilation.

Question 39

how to treat respiratory alkalosis

Answer 39

mechanical ventilation, "re-breathing" (brown paper bag), sedatives prevention of altitude sickness with acetazolamide 1-2 days before ascent and continuing 2 days after arrival at altitude.

Question 40

signs of metabolic alkalosis

Answer 40

pH > 7.45 HCO3 > 26

Question 41

2 different etiologies of metabolic alkalosis

Answer 41

Chloride responsive (Cl urine < 15) Chloride resistant (Cl urine > 25)

Question 42

what to do if chloride responsive metabolic alkalosis?

Answer 42

calc chloride deficit (0.2 L/kg x kg) x (103- actual Cl) replace chloride deficit with normal saline: Chloride deficit (mEq)/ 154 mEq/L

Question 43

what to do if chloride resistant metabolic alkalosis?

Answer 43

decrease/change corticosteroids +/- spironolactone 100-400 mg/day in 1-2 divided doses replete magnesium then potassium acetazolamide 500 mg IV/PO daily