Acid-Base Balance

Question 1

What common conditions lead to acid-base imbalances?

Answer 1

COPD, DM, kidney disease, sepsis, NVD

Question 2

What 3 systems does homeostasis refer to?

Answer 2

Fluid imbalance (hypo/hypervolemia, third spacing)

Electrolyte imbalance (Na, K, Ca, Mg, P)

Acid-base imbalance (respiratory/metabolic acidosis/alkalosis)

Question 3

External respiration

Answer 3

breathing in O2 and breathing out CO2 and H2O

Question 4

Internal respiration

Answer 4

tissue level: arterial capillary beds allow diffusion of O2 into cell and the venule capillary beds release CO2 into the plasma for return back to the lungs

Question 5

What percent of O2 is carried attached to Heme?

Answer 5

98.5%, the rest diffuses freely into the blood

Question 6

What is the action of bicarb once it’s in the lungs? (primary regulatory mechanism)

Answer 6

HCO3 → Carbonic Acid (H2CO3) → H2O (vapor) and CO2 (exhaled)

Question 7

When does the buffer system react? And how?

Answer 7

immediately

Chemical buffering in plasma and cells by taking CO2 and H2O → H2CO3 → HCO3 and H+
Electrolyte exchange in cells - K+ with H+ (alkalosis → hypokalemia, acidosis → hyperkalemia)

Question 8

When does the respiratory buffer system react? And how?

Answer 8

Responds in minutes maximum, effectiveness reached within hours. “Blow off” CO2 to increase pH.

Question 9

When does the renal buffer system react? And how?

Answer 9

2-3 days to reach max response, but can maintain balance for a long time. Excrete H+ and reabsorb HCO3 to increase pH.

Question 10

Causes of Respiratory Acidosis

Answer 10

anything causing hypoventilation
- COPD (high levels of CO2)
- Barbiturate or sedative overdose
- Severe pneumonia
- Atelectasis
- Resp muscle weakness
- Mechanical hypoventilation
- opioids causing bradypnea

Question 11

Manifestations of Respiratory acidosis

Answer 11

CNS: drowsiness, headache, coma, dizziness, seizures
CV: ↓BP, ventricular fibs, warm flushed skin (peripheral vasodilation)

Question 12

Causes of Respiratory Alkalosis

Answer 12

anything causing hyperventilation
- hypoxia, fear/anxiety, fever
- CNS disorders, sepsis, brain injury, salicylate poisoning, mechanical overventilation

Question 13

Manifestations of Respiratory Alkalosis

Answer 13

CNS: lethargy, lightheadedness, confusion
CV: ↑ HR, dysrhythmias
GI: NV, epigastric pain
Neuromuscular: tetany, numbness, tingling of extremities, hyperreflexia, seizures

Question 14

Manifestations of Respiratory Alkalosis

Answer 14

CNS: lethargy, lightheadedness, confusion
CV: ↑ HR, dysrhythmias
GI: NV, epigastric pain
Neuromuscular: tetany, numbness, tingling of extremities, hyperreflexia, seizures

Question 15

Causes of Metabolic Acidosis

Answer 15

Accumulation of acid (DKA, septic shock - lactic acid accumulation, starvation)
Loss of bicarbonate (diarrhea, renal failure)

Question 16

Manifestations of Metabolic Acidosis

Answer 16

CNS: drowsiness, confusion, headache, coma
CV: ↓BP, dysrhythmias, warm flushed skin (peripheral vasodilation)
GI: NVD, ab pain

Question 17

Causes of Metabolic Alkalosis

Answer 17

Loss of acid (NG suctioning, prolonged vomit, loss of K+ in diuretic therapy)
Gain in HCO3 (ingesting baking soda)

Question 18

Manifestations of Metabolic Alkalosis

Answer 18

CNS: dizziness, irritability, nervousness, confusion
CV: tachycardia, dysrhythmias
GI: anorexia, NV
Neuromuscular: tremors, hypertonic muscles, muscle cramps, tetany, tingling of extremeties
Resp: hypoventilation

Question 19

Drug therapy for Metabolic Alkalosis

Answer 19

acetazolamide - promotes loss of HCO3 in urine

Question 20

Drug therapy for Metabolic Acidosis

Answer 20

Sodium bicarbonate (baking soda)

Question 21

CO2 and pH have an

Answer 21

inverse relationship

Question 22

HCO3 and pH have a

Answer 22

direct relationsihp

Question 23

Normal ABG values

Answer 23

pH: 7.35-7.45
PaO2: 80-100 mmHg
PCO2: 35-45 mmHg
HCO3: 22-26 mEq/L