Acid Base

Question 1

pH

Answer 1

7.35-7.45

<7.35 acidic

> 7.45 basic

Question 2

pCO2

Answer 2

35-45 mmHg

<35 basic

> 45 acidic

(reversed)

Question 3

PO2

Answer 3

80-100 mmHg

Question 4

HCO3

Answer 4

22-26 mEq/L

<22 acidic

> 26 basic

Question 5

Acidemia

Answer 5

abnormally low pH

Causes:
(Respiratory) pCO2 >45 mmHg, decrease in minute ventilation (hypoventilation)

(metabolic) serum HCO3- <22 mEq/L, increased acid production, acid ingestion, decreased renal acid excretion, GI or renal loss of HCO3-

Question 6

Manifestations of Acidemia

Answer 6

Manifestations:

CV: impaired cardiac contractility, decreased cardiac output and decreased BP,

Neuro: inhibition of metabolism, obtundation and coma,

Respiratory: Kussmaul breathing (compensatory hyperventilation),

Metabolic: increased oxyhemoglobin dissociation, reduction in ATP synthesis

Hyperkalemia, protein degradation

Question 7

Alkemia

Answer 7

abnormally high pH

Causes

(Respiratory) pCO2 <35 mmHg, increase in minute ventilation (hyperventilation)

(metabolic) serum HCO3- >26 mEq/L, acid loss, HCO3 retention or ingestion

Question 8

Manifestations of Alkemia

Answer 8

(CV) arteriolar constriction, reduced coronary blood flow —> reduced anginal threshold, dysrhythmias

(neuro) tetany, seizures, lethargy, delirium
(respiratory) , compensatory hypoventilation, hypercapnia and hypoxemia
(metabolic) hypokalemia, hypomagnesmia

Decreased iCa++, decreased oxyhemoglobin dissociation

Question 9

Acidosis

Answer 9

(pH is low)

respiratory (pCO2 >45 mmHg)

metabolic (Serum HCO3- <22 mEq/L)

Question 10

Alkalosis

Answer 10

(pH is high)

respiratory (pCO2 < 35 mmHg)

metabolic (serum HCO3- >26 mEq/L)

Question 11

Primary vs. Compensatory

Answer 11

Respiratory disorder compensation > Kidneys (H+/bicarb)

Metabolic disorder compensation > Lungs, then kidneys

Respiratory disorders CANNOT be compensated by the lungs

Question 12

Acid Base Disorders

Answer 12

classified as metabolic if the change in pH is primary due to an alteration in serum HCO3- and respiratory if the change is primarily due to a change in PCO2 (increase or decrease in ventilation)

result in compensation that tends to normalize the pH

Question 13

Metabolic Acid Base disorders

Answer 13

result in compensation by the respiratory system (change in PCO2)

Question 14

Respiratory Acid Base Disorders

Answer 14

Result in compensation by the metabolic system (change in HCO3)

Cannot be compensated by the respiratory system

Question 15

Acid Base Mnemonic ROME

Answer 15

Respiratory 
Opposite 
 -Alkalosis ^ pH and v HCO3 or PaCo2
-Acidosis vpH and ^ HCO3 or PaCo2
Metabolic
Equal
-Acidosis v pH v HCO3
-Alkalosis ^ pH ^ HCO3

Question 16

Respiratory Regulation

Answer 16

occurs within minutes, lasts 12-24 hours

lungs eliminate CO2

as CO2 increases, the pH decreases

Question 17

Renal Regulation

Answer 17

slower to act, but lasts longer

eliminates H+

reabsorb HCO3-

create HCO3-

Question 18

Chemical Buffer System

Answer 18

resist change in pH

first line of defense (immediate)

Buffers work by : releasing hydrogen ions when pH increases and binding hydrogen ions when pH decreases

Question 19

Four Major Chemical Buffer Systems

Answer 19

1. bicarbonate buffer system
2. transcellular H//K exchange system
3. Protein buffer system (amphoteric)
4. Bone