Acid/Base

Question 1

Haldane effect:

Answer 1

O2 binding to Hb reduces CO2 affinity

Question 2

Henderson Hasselbach eq: with HCO3

Answer 2

pH = 6.1 + [HCO3-]/ (0.03 * PaCO2)

or

pH = 6.1 * [HCO3-]/ [CO2]

Question 3

High or Low pH? Due to what? Compensation?

1. Respiratory alkalosis
2. Respiratory acidosis

Answer 3

1. Respiratory alkalosis
   - ↑pH, due to ↓ CO2
   - Cause: hyperventilation (high altitude)
   - Compensation: ↓HCO3- reabsorption
2. Respiratory acidosis
   - ↓pH, due to ↑ CO2
   - cause: hypoventilation, severe obstructive disease, drug overdose
   - Compensation: ↑HCO3-

• note: for resp compensation, HCO3- rise/fall will follow CO2 to counterbalance it
• chronically, for every 1 Torr increase in CO2, HCO3- increases about 0.4

Question 4

High or Low pH? Due to what? Compensation?

3. Metabolic alkalosis
4. Metabolic acidosis

Answer 4

3. Metabolic alkalosis
   - ↑ pH due to low non-CO2 acid
   - Cause: vomiting (lose gastric acid)
   - Compensation: ↓ Ventilation in order to accumulate CO2 in blood
4. Metabolic acidosis
   - ↓ pH due to high non-CO2 acid
   - causes: MUDPILES, diarrhea (loss of HCO3-)
   - compensation: ↑ ventilation

Question 5

When you vomit, what do you lose?

Diarrhea?

Answer 5

VOmit: lose HCL
Diarrhea: lose HCO3-

(these are nonCO2 substances that affect pH)

Question 6

Normal values for Denver :
●	pH = 
●	PaCO2 = 
●	PaO2 = 
●	[HCO3-] =

Answer 6

Normal values for Denver :
●	pH = 7.40 
●	PaCO2 = 36 Torr 
●	PaO2 = 80 Torr
●	[HCO3-] = 22 mEq/L

Question 7

How does acetazolamide (diamox) work?

- what is it used to treat/prevent?

Answer 7

causes metabolic acidosis → body wants normal pH (hyperventilate) → PaO2

acute mt sickness

Question 8

How does dexamethasone work? What is it used to treat?

Answer 8

Alters gene expression that causes brain edema: treat acute mt sickness

• high altitude cerebral edema (HACE)

Question 9

What is “the bends”

• cause
• symptoms
• treatment?

Answer 9

decompression sickness related to diving

cause: rapid ascent
symptoms: limb pain, numbness, parasthesia, dizziness
treatment: recompression (descend again if safe), hyperbaric chamger if severe to push gas back into dissolved state

Question 10

What is getting “Narc’d”

• who gets it
• symptoms

Answer 10

Nitrogen narcosis

• people who dive deep and breath too much compressed room air → nitrogen in brain causes altered mental status
• symptoms: poor judgement, euphoria, confusion, like intoxication

Question 11

Barotrauma

• how do you get it?
• who gets it?

Answer 11

↑ P in airways can lead to extravasation of air along bronchial tree (push gas from alveolar spaces to interstitium → pneuomothorax

• happens to poorly controlled asthmatics, people with lung blebs, free dives

Question 12

Shallow water Blackout

• what causes it
• who gets it

Answer 12

Cause: forced hyperventilation (but brain values PaCO2> PaO2) and if PaO2 decreases enough, you become anoxic, passout, drown

• Breath holder, free divers, swimmers