Study Guide Acid-Base Balance & Fluid/Electrolyte Imbalances

Quiz 1 of Patho/Phys 2

Normal pH values

7.35 - 7.45

Normal PaCo2 values

35 - 45 mm Hg

Normal HCO3 values

22 - 26 mEq/L

Normal Sodium values

135 - 145 mEq/L

Normal Potassium values

3.5 - 5.0 mEq/L

Normal calcium values

8.5 - 10.5 mg/dL

ROME Method abbreviaiton meaning

Respiratory = Opposite ; Metabolic = Equal

What does it mean when pH ↓ and CO2 ↑ ?

Respiratory Acidosis

What does it mean when pH ↑ and CO2 ↓ ?

Respiratory Alkalosis

What does it mean when pH ↓ and HCO3 ↓ ?

Metabolic Acidosis

What does it mean when pH ↑ and HCO3 ↑ ?

Metabolic Alkalosis

Compensation Quick Check (Uncompensated)

Means the organs are not responding yet to help regulate. Not enough time has passed.

• pH value abnormal

• only 1 value abnormal

  • Either Co2 or Hco3

Compensation Check (Partially Compensated)

Chemical buffers responded immediately, attaching to extra acid or bases to minimize pH changes and lungs started to slow/fast breathing within a couple of minutes to stabilize it as well. Kidneys responded within hours - days to produce bicarbonate/excrete bicarbonate but enough yet to fully stable

• pH value abnormal

• Both values abnormal

  • Both Co2 and Hco3

Compensation Check (Fully Compensated)

The Kidneys have fully produced enough bicarbonate/filtered enough to be excreted which finally stabilizes the pH blood level back to normal. But underlying problem is still there and needs to be treated.

• pH value normal

• Both values abnormal

  • Both Co2 and Hco3

Respiratory Acidosis Cause

↑CO₂ = ↓pH

Hypoventilation (not breathing enough)

Respiratory Acidosis Think

↑CO₂ = ↓pH

COPD (Chronic Obstructive Pulmonary Disease)

• Lungs airflow are blocked (I.e. excess thick mucus, swollen/narrow airways, floppy/collapsed airsacs)

Obesity/Apnea

Pneumonia

Opioid Overdose

Priority to address Respiratory Acidosis

Improve ventilation

Respiratory Alkalosis Cause

↓CO₂ = ↑pH

Hyperventilation (breathing too much)

Respiratory Alkalosis Think

↓CO₂ = ↑pH

Anxiety

Pain

Fever

Sepsis

Priority for Respiratory Alkalosis

Treat underlying cause

• Anxiety or Panic Attacks (hyperventilation

• Severe pain

• High fever

• Sepsis

• Hypoxia (not enough O2 in blood)

• Mechanical Ventilation set too high

Metabolic Acidosis Cause

↓HCO₃⁻ = ↓pH

• Too much acid or loss of base

Metabolic Acidosis Think

↓HCO₃⁻ = ↓pH

• Diarrhea (loses HCO3)

• DKA (diabetic ketoacidosis)

• Kidney Failure

Metabolic Acidosis Key Sign

Kussmaul’s respirations (deep, rapid breaths RR)

Metabolic Alkalosis Causes

↑HCO₃⁻ = ↑pH

Loss of acid or too much base

Metabolic Alkalosis Think

• Vomiting

• NG suction (lose stomach acid)

• Diuretics

Metabolic Alkalosis Watch For

Hypokalemia (often occurs together)

Normal Range for Sodium value

135 - 145 mEq/L

Normal Range for Potassium Level

3.5 - 5.0 mEq/L

Normal Range for Calcium Level

8.5 - 10.5 mg/dL

or

4.5 - 5.5 mg/dL (ionized)

What can cause Hyponatremia? What is the lab value?

Na+ <135

• Diuretics

• Diarrhea

• Vomiting

• NG suction

What can cause Hypernatremia? What is the lab value?

Na+ >145

• Dehydration

• Renal Failure

• Corticosteroids

What is a sign of Hyponatremia?

• Confusion (#1 sign) (brain swelling)

What is a sign of Hypernatremia?

• Confusion

• Agitation

• Muscle weakness

What is Severe Treatment for Hyponatremia?

• 3% hypertonic saline

• Correct slowly (max 8-10 mEq/L per 24 hrs)

What is a treatment for Hypernatremia?

• Isotonic fluids first

• Then Hypotonic

• Correct slowly (max 0.5 mEq/L per hour)

What causes Hypokalemia? What is the lab value?

K < 3.5

• #1 Cause: Diuretics (Lasix)

Cardiac Risk with Hypokalemia

• Dysrhythmias (irregular rhythm)

• ↑ Digitalis Toxicity

Treatment with Hypokalemia

IV K+ (NEVER BOLUS)

• Max 10-20 mEq/hr peripheral

Foods

• bananas, potatoes, spinach

what causes Hyperkalemia? What is a lab value?

K > 5.0

#1 Cause: Renal Failure

LIFE THREATENING

What is the Risks and ECG changes of Hyperkalemia?

• Cardiac Arrest risk

• ECG Changes: Tall Peaked waves → Wide QRS → Sine Wave

Emergency Treatment of Hyperkalemia

1. Calcium (protects heart)

2. Insulin + D50 (shifts K into cells)

3. Lasix, Kayexalate, or dialysis (removes K+)

What causes Hypocalcemia? What is a lab value?

Low levels of calcium in blood. Ca < 8.5

What are key signs of Hypocalcemia?

Ca < 8.5

• Trousseau’s sign (carpopedal spasm with BP cuff)

• Chvostek’s sign (facial twitchting)

• Tingling, Tetany, Seizures

Hypocalcemia Treatment

Calcium gluconate IV (Give slowly!)

what causes Hypercalcemia? What is a lab value?

Ca > 10.5

• Hyperparathyroidism

• Malignancy

• Thiazide Diuretics

Treatment of Hypercalcemia

Aggressive hydration with normal saline + Lasix

What type of IV is 0.9% NS & Lactated Ringers? What is it used for?

Isotonic ; stays in vessels

• Dehydration

• Hypovolemia

What type of IV is a D5W (Dual Nature)? What is it used for?

Isotonic initially → hypotonic

• Metabolizes dextrose (sugar) to curve hunger

• Becomes plain/free water once sugar is metabolized by cells (hypotonic)

• Used when someone is temporarily NPO (i.e. prep for surgery and can’t eat anything)

What type of IV is 0.45% NS? What is it used for?

Hypotonic ; Fluid INTO → cells

• Used for Hypernatremia

What type of IV is 3% NS? What is it used for?

Hypertonic ; Fluid LEAVES ← Cells

• Used for Severe Hyponatremia

• Rarely used, dangerous

CO2 is a(n) _______

Acid

• More CO2 = more acidic

HCO3 is a(n) _______

Base

• More Bicarb = more alkalotic

Metabolic problem → ______ help (____)

Lungs help (fast)

Respiratory problem → ________ help (______)

Kidneys help (slow)

Electrolyte + Acid often connected: vomiting/NG tube leads to what?

Vomiting/NG → Metabolic Alkalosis + hypokalemia

Electrolyte + Acid often connected: Diarrhea tube leads to what?

Diarrhea → metabolic acidosis

Diarrhea→ Loses HCO₃⁻ → Metabolic Acidosis

What will you look for? pH ____HCO₃_____ CO₂_______

pH ↓ HCO₃ ↓ CO₂ ↓

NG tube drainage → Loses stomach acid (HCO3) → Metabolic Alkalosis

What will you look for? pH ____HCO₃_____ CO₂_______

pH ↑ HCO₃ ↑ CO₂ ↑

Morbid obesity→ Hypoventilation → Respiratory Acidosis

What will you look for? pH ____HCO₃_____ CO₂_______

pH ↓ HCO₃ ↑ CO₂ ↑

Hyperventilation → Too much breathing → Respiratory Alkalosis

What will you look for? pH ____HCO₃_____ CO₂_______

pH ↑ HCO₃ ↓ CO₂ ↓