MedSurg 3 - Acid-Base Imbalances (Chap 14)

Question 1

Acid-base balance

Answer 1

the process of carefully regulate hydrogen ion (H+) production and elimination

Question 2

Normal arterial pH // venous blood

Answer 2

arterial = 7.35 to 7.45 ; venous = 7.31 to 7.41

Question 3

Carbonic Anhydrase Equation

CO2 + H2O H2CO3 HCO3 + H

Answer 3

H2CO3 – Carbonic Acid – common ACID in the body.
HCO3 – Bicarbonate – common BASE in the body.

** As CO2 increases, more H+ is created. – Which means the more CO2 retained in the body, the more acid is produced. **

Question 4

metabolism of Carbohydrate, protein and Fat

Answer 4

CARBOHYDRATE metabolism forms CO2.

**Incomplete breakdown of glucose which occurs whenever cells metabolize under ANAEROBIC (no oxygen) condition forms LACTIC ACID. This occurs when body has very little oxygen to meet metabolic oxygen demands such as heavy exercise, seizure activity, fever, and reduced oxygen intake.
Anaerobic condition occur with HYPOXIA, SEPSIS & SHOCK.

Question 5

metabolism of protein

Answer 5

PROTEIN breakdown forms SULFURIC ACID.

Question 6

metabolism of Fat

Answer 6

FAT breakdown forms FATTY ACID & KETOACIDS.

** Incomplete breakdown of FATTY ACIDS occuring when large amount of fatty acids are being metabolized forms KETOACIDS.

Question 7

Kidney Movement of Bicarbonate – the 1st kidney pH control action

Answer 7

When blood pH changes are persistent, kidney actions that increase excretion and reabsorption rates of acids or bases (depending on the direction of the pH changes) begin to operate. These actions are kidney movement of bicarbonate, formation of acids, and formation of ammonium.

Question 8

Formation of ACIDs – the 2nd kidney pH control action

Answer 8

When blood hydrogen ion levels is high, this bicarbonate is reabsorbed from the kidneys back into the circulation, where it can help buffer excess hydrogen ions. In this situation, the kidney tubules also can make additional bicarbonate and reabsorb it for an increase buffer effect. When blood hydrogen ion levels are low, the bicarbonate remains in the urine and is excreted.

Question 9

Formation of AMMONIUM – the 3rd kidney pH control action

Answer 9

Ammonia (NH3), which is formed during normal protein breakdown, is converted into Ammonium (NH4). The ammonia that is secreted into the urine where it is combined with the excess hydrogen ion to form ammonium. The ammonium traps the hydrogen ions and then excreted in the urine. The result is loss of hydrogen ions and an increase in blood pH.

Question 10

Cause of Acidosis

Answer 10

Overproducing ACID – Ex. Diabetic Ketoacidosis and Seizures.

Underelimiminating ACID – Ex. Respiratory and/or Kidney Impairment

Question 11

Metabolic Acidosis

Answer 11

Four Process that cause metabolic Acidosis:

• Overproduction of Hydrogen ions
• Underelimination of Hydrogen ions
• Underproducion of Bicarbonate ions
• Overelimination of Bicarbonate ions

Question 12

Metabolic Acidosis (con't) 
- overproduction & underelimination of acid

Answer 12

Overproduction of acid:
– Excessive intake of acids such as: Alcoholic beverages, Methyl Alcohol, Acetylsalicylic Acid (Aspirin)

Underelimination of acid:
– Kidney Failure and Lung Problem

Question 13

Metabolic Acidosis (con't) 
- underproduction & over-elimination of bicarbonate

Answer 13

Underproduction of bicarbonate:
– Because bicarbonate is made in the kidney and pancreas, kidney failure and impaired liver or pancreatic function can cause base-deficit acidosis.

Over-elimination of Bicarbonate:
– Diarrhea can cause bicarbonate lost.

Question 14

Manifestation of ACIDOSIS

Answer 14

ACIDOSIS reduces the ability of excitable membranes to respond appropriately, especially in cardiovascular tissue, neurons, skeletal muscle, and GI smooth muscle

Cardiovascular:
Early changes – increase HR and CO
Worsening Acidosis and HYPERKALEMI A – HR decreases, T-Waves become tall and peaked, QRS are widened. Peripheral pulses are hard to find. Hypotension bec of vasodilation.

Question 15

Manifestation of ACIDOSIS

– Cardiovascular

Answer 15

Early changes:
– increase HR and CO

Worsening Acidosis and HYPERKALEMIA:
– HR decreases, T-Waves become tall and peaked, QRS are widened. Peripheral pulses are hard to find. Hypotension bec of vasodilation.

Question 16

Manifestation of ACIDOSIS

– Central Nervous System (CNS)

Answer 16

Depression of CNS function
– Lethargy to Confusion (esp. in older adults)

As acidosis worsens:
– may become Unresponsive

** assess mental status

Question 17

Manifestation of ACIDOSIS

– Neuromuscural

Answer 17

reduced Muscle tone and deep tendon reflexes
- cause of these are hyperkalemia along with acidosis.

** assess muscle strength

Question 18

Manifestation of ACIDOSIS

– Respiratory

Answer 18

** Assess RATE, DEPTH, and EASE of Breathing. Check Pulse Oximetry.

Metabolic Acidosis:
– Breaths are RAPID and DEEP as hydrogen level rises and not under voluntary control. – called KUSSMAUL Respiration.

Respiratory Acidosis:
– Breaths are SHALLOW and RAPID. Muscle weakness makes this problem worse!

Question 19

Manifestation of ACIDOSIS

– Skin

Answer 19

Metabolic Acidosis:
– Means breathing is NOT impaired, the rate is increased and CO2 is lost. This caused vasodilation and makes the skin WARM, DRY, and PINK.

Respiratory Acidosis:
– Breathing is impaired, so skin is PALE to CYANOTIC.

Question 20

ABG Values

Answer 20

pH —- 7.35 to 7.45
PaO2 —- 80 to 100
PaCO2 — 35 to 45
HCO3 — 21 to 28

Question 21

Metabolic Alkalosis - Etiology

Answer 21

Base (Bicarb) Excess:

• excessive intake of bicarbonates, carbonates, acetate, citrate
• Ex. excessive use of Oral antacids containing sodium bicarbonate or calcium bicarbonate

Acid Deficit:

• Prolonged Vomiting
• Prolonged Gastric Suctioning
• Excess cortisol
• Hyperaldosteronism
• Use of Thiazide Diuretics

Question 22

Respiratory Alkalosis - Etiology

Answer 22

Excessive loss of CO2:

• HYPERVENTILATION (rapid respirations) due to:
• —– anxiety, fear, or improper setting on mechanical ventilators.
• —– hyperventilation can also result from direct stimulation of central respiratory centers bec of: fever, certral nervous system lesions, and salicylates

Question 23

Manifestation of Alkalosis

-s/s are the same for respiratory & metabolic alkalosis:

Answer 23

Many S/S are the result of:

• Hypocalcemia
• Hypokalemia

** These problem change the function of the nervous system, neuromuscular, cardiac, and respratory.

Question 24

Manifestation of Alkalosis

– CNS

Answer 24

Caused by overexcitement of the nervous system:

• Dizziness
• Agitation
• Confusion
• Hyperreflexia, which may progress to seizure
• Tingling or numbness around the mouth and toes
• Positive Chvostek’s & Trousseau’s sign

Question 25

Manifestation of Alkalosis

– Neuromuscular

Answer 25

Related to Hypocalcemia & hypokalemia:

• Muscle Cramps
• Twitches
• “Charley Horses”
• Deep Tendon reflexes are hyperactive
• TETANY (continuous contractions) of muscle groups may be present —– painful and indicates a rapidly worsening condition
  
  • ** Skeletal muscle may contract as a result of over stimulation, but they become weaker bec of hypokalemia:
• Handgrip decrease
• unable to stand or walk
• Respiratory effort is less effective as skeletal muscle weakens

Question 26

Manifestation of Alkalosis

– Cardiovascular

Answer 26

Cardiovascular Changes bec of Increase in Myocardial irritability, esp when accompanied with hypokalemia:

• HR increase
• Pulse is thready
• Severe Hypotension (if hypovolemia is also present)
• Risk for Digoxin Toxicity (hypokalemia increases myocardial sensitivity to digoxin)

Question 27

Manifestation of Alkalosis

– Respiratory

Answer 27

• Increase Respiratory Rate (caused by anxiety or physiologic changes)

Question 28

Interventions for Alkalosis

Answer 28

• • Prevent further loss of Hydrogen, Potassium, Calcium, Chloride ions
• ** STOP or MODIFY: suctioning, infusion of IV solutions containing bases, drugs that promote hydrogen excretion
• • Restore fluid balance
• ** Fluid and electrolyte replacement
• ** Antiemetic (if caused by vomiting)
• • Monitor Changes
• ** Adjust fluid & electrolyte therapy
• ** Monitor electrolyte values daily until normalized
• • Provide Patient Safety
• ** PREVENT FALL ( bec pt has muscle weakness and hypotension)