Acid Base Abnormalities Lecture Powerpoint

Question 1

Arterial blood gas measure functions (3)

Answer 1

A method to assess oxygenation of blood plasma***, evaluate acid base status, and monitor therapy

Question 2

A-a gradient and how is it measured?

Answer 2

• Measure of lungs ability to transfer o2 from atmosphere to pulmonary circulation, if very high then not transferring (ventilating but not entering circulation), normal means it is.
• Measured normal = age/4

Question 3

Increased A-a gradient can indicate these 3 pathologies

Answer 3

• congestive heart failure
• adult respiratory distress syndrome
• lobar pneumonia

Question 4

Most common reason for a V/Q mismatch, and 2 other common causes

Answer 4

• Pulmonary emboli
• pneumonia
• pneumothorax

Question 5

Alveolar hypoventilation is often due to…

Answer 5

….interstitial lung disease

Question 6

Ways to attain ABG (2) and technique

Answer 6

• Radial artery stick
• Femoral artery stick (can’t be on any anticoag, need to put pressure on longer)

-use heparanized syringe, it fills passively, remove all air bubbles, transport on ice

Question 7

Allyn test in attaining ABG using radial artery stick

Answer 7

Used to assess ulnar radial artery anastomosis before acquiring specimen for ABG by occluding both radial and ulnar artery, having patient pump fingers, then release the ulnar and watch entire hand refill - ensures that the hand is dual perfused so ABG stick in radial artery doesn’t cut off supply

Question 8

PCO2 2 mech of removal from the body

Answer 8

• removal of bicarb

- exhalation of CO2

Question 9

A ___ mmHg change of PCO2 is equivalent to a ___ change in pH which is equivalent to a ___ MEQ change in base

Answer 9

12, .1, 6

Question 10

Definition of a volatile acid and example

Nonvolatile acids are typically…

Answer 10

An acid that readily dissociates in air, H2CO3

….nonvolatile acids

Question 11

Strong vs weak acid/base

Answer 11

Completely dissolute in water while weak incompletely dissolute in water

Question 12

buffer

Answer 12

A weak acid/base combo that will resist change in pH, predominantly proteins intracellularly and predominantly NaHCO3 (bicarb) extracellularly (weak base)

Question 13

Treatment for respiratory acidosis

Answer 13

Increase ventilation to remove volatile acids from blood stream

Question 14

Postprandial alkaline tide

Answer 14

Refers to how upon eating a meal there can be a slight alkalosis that occurs in the blood stream because HCl is used in digestion and intracellular Bicarb is released into the plasma to compensate

Question 15

ABG stepwise approach (oh good lord 6 steps)

Answer 15

1) Is pH acidotic (<7.35) or alkalotic (>7.45) or normal? (May be normal in fully compensated condition)
2) Is PCO2 respiratory acidotic (>45), respiratory alkalotic (<35) or normal?
3) Is HCO3- metabolic acidotic (<22), metabolic alkalotic (>26), or normal?
4) Match the pCO2 and HCO3- with pH, find if the out of normal range one is going in same direction (High pCO2 with low pH and vise versa, low HCO3- with low pH)
5) If CO2 and HCO3- are going opposite direction of the pH, then this is compensation
6) Uncompensated pH is out of normal range, while partially compensated is 7.35-7.39 or 7.41-7.44

Question 16

Gold standard test to determine pH and oxygenation of the bloodstream

Answer 16

Arterial blood gas

Question 17

Hemoglobin and protein molecules in blood shift the physiologic pH of blood from ___ to ____ resting value

Answer 17

7, 7.35-7.45

Question 18

Difference between arterial blood gas and pulse oximetry

Answer 18

Pulseox measures % sat of hemoglobin molecule which isn’t good indicator of overall oxygenation of blood (cause you might only have 10 hemoglobin molecules), arterial blood gas measures partial pressure of free O2 dissolved in plasma

Question 19

An A-a gradient can still be normal in conditions that involve…

Answer 19

…hypoventilation

Question 20

Base excess

Answer 20

A positive or negative measure of how much base is needed to bring pH back to physiologic limits (i.e. -8 means we need 8 more units of base to return to physiologic normal, +8 means we need 8 fewer units of base), more accurate than HCO3- levels

Question 21

Normal acid base balance values

Answer 21

pH = 7.35-7.45
PaCO2=35-45 mmHg
HCO3=22-26meq/L
PAO2 and PaO2=80-106mmHg
Base excess= +/-2

Question 22

The anion gap and normal values

Answer 22

The difference between Na+ - (Cl- + HCO3-) and should normally be between 8-15 mEQ/L, but elevated levels indicate buildup of metabolic acids (metabolic acid)

Question 23

Only time IV bicarb is given is what condition?

Answer 23

Metabolic acidosis to drive K+ back into cells

Question 24

HCO3 is <24 in ____ acidosis or compensation for ____ alkalosis

Answer 24

metabolic, respiratory

Question 25

Issue with giving a patient to high of O2 levels

Answer 25

The nitrogen conc of air is important as surfactant to keep alveoli from collapsing and therefore if not a large enough portion of the air content can see atelectasis of alveoli

Question 26

30-60 rule and 60-90 rule

Answer 26

Refers to general rule that a PaO2 of 30=60% hemoglobin saturation, while a PaO2 of 60=90% saturation

Question 27

Healthy satO2 in blood

Answer 27

> 94%

Question 28

PaO2 levels interpretation and what does this indicate?

Answer 28

Normal 80-106
mild hypoxia 60-79
mod hypoxia 40-59
severe hypoxia <39

Determines need of oxygen therapy

Question 29

Immediate treatment for carbon monoxide poisoning

Answer 29

Extreme O2 supplementation or use of a dive chamber

Question 30

Despite good hem saturation, o2 might not be able to unload at the tissue if the blood pH is measured to be….

Answer 30

…alkalotic

Question 31

Net result of left shift and right shift in oxy hemoglobin dissociation curve

Answer 31

• More O2 taken up by HGB but less released

- Less O2 taken up by HGB but more released at tissues

Question 32

In patients with respiratory acidosis or alkalosis, we often do not see ___ because they are often COPD or other obstructive dz patients

Answer 32

Respiratory compensation

Question 33

Respiratory and renal compensation

Answer 33

• Respiratory is achieved rapidly by elimination or retention of CO2 via hyper or hypoventilation
• Renal is achieved slowly by secretion or reabsorption of H+ and HCO3-

Question 34

metabolic acidosis 2 subgroups

Answer 34

• Increased anion gap due to metabolic biproduct buildup

- normal anion gap seen with excessive bicarb loss

Question 35

Extreme acidosis will see….

Answer 35

….removal of ca2+ from bone and excretion in urine resulting in wasting of skeletal structures

Question 36

Metabolic alkalosis 2 subgroups

Answer 36

• Excessive gain of bicarb often thru ingestion

- Excessive H+ loss often from vomiting or hypokalemia

Question 37

Standard in treatment of metabolic alkalosis

Answer 37

KCl and saline

Question 38

Respiratory acidosis 3 subgroups

Answer 38

• depression of respiratory centers
• lung disease
• disorders of respiratory muscles

Question 39

Respiratory acidosis treatment

Answer 39

Improve ventilation sometimes mechanically

Question 40

respiratory alkalosis is usually caused by…

Answer 40

…anxiety or psychogenic source