Exam 1 - Acid-Base

acid base disturbances are used to determine ...

the cause of a disorder and the appropriate treatment

plasma pH indicates?

Indicator of hydrogen ion (h+) concentration

normal pH of blood

7.35-7.45

Acidic vs alkalotic state

Acidic:

High H+ concentration

pH < 7.35

Alkalotic:

Low H+ concentration

pH > 7.45

how do buffer systems prevent major changes in the pH of body fluids

Accomplish this by either removing or releasing H+

intracellular vs extracellular buffer system

Intracellular Buffer System:

Proteins, phosphates, hemoglobin (in RBCs)

Extracellular Buffer System: Bicarbonate-carbonic acid buffer system

-20 parts bicarbonate (HCO3-) to 1 part of carbonic acid (H2CO3)

what is the normal bicarbonate carbonic acid ratio

20 parts bicarbonate (HCO3-) to 1 part of carbonic acid (H2CO3)

if this is disrupted it causes acid-base imbalance

CO2 dissolved in water becomes...

carbonic acid

kidneys role in ABG

Excrete hydrogen ions and conserve/regenerate/excrete bicarbonate ions

NORMAL ABG VALUES

pH: 7.35-7.45

PCO2: 35-45

Bicarb: 22-26

PaO2: 80-100

t/f renal compensation for ABG imbalances is rapid

false its slow

anion gap

Difference between the sum of all cations and the sum of all anions in blood

Helps point to the cause of the imbalance

equation, dont need to memorize: Na+ – (Cl- + HCO3-)

2 forms of metabolic acidosis

High Anion Gap Metabolic Acidosis

Normal Anion Gap Metabolic Acidosis

Normal Anion Gap vs. High Anion Gap Metabolic Acidosis

Normal is caused by direct loss of bicarbonate

-->Examples: diarrhea, diruetics, renal insufficiency, excessive chloride administration

High is caused by:

Excessive accumulation of acids

-->Examples: lactic acidosis, salicylate poisoning, renal failure, DKA, starvation

metabolic acidosis clinical manifestations

Confusion

Drowsiness

Increased respiratory rate & depth

Nausea and Vomiting

Low blood pressure

Cold/Clammy skin

Arrhythmias

Shock

metabolic acidosis can cause what electrolyte imbalance

potassium, so pt should have ECG monitoring if they have metabolic acidosis

chronic metabolic acidosis can cause what electrolyte problem (other than K+)

LOW serum calcium levels, so assess for tetany with chronic metabolic acidosis

metabolic acidosis treatment

-give bicarb

-monitor potassium/treat accordingly

-monitor for low calcium and assess for tetany

-dialysis

normal anion gap value

8-12 mEq/L

a high anion gap is caused by

Diarrhea

Dehydration

Kidney Disease

Diabetes(DKA)

Salicylate poisoning(Aspirin)

a low anion gap is caused by

Kidney disease

Heart disease

Liver disease

metabolic alkalosis causes

-Severe vomiting

-Gastric suctioning (Loss of stomach HCl)

-Associated with loss of potassium (Use of diuretics)

-Associated with ACTH secretion (Hyperaldosteronism, Cushing's syndrome)

metabolic alkalosis clinical manifestations

SYMPTOMS R/T HYPOCALCEMIA (Tinglings of fingers and toes, dizziness, tetany)

* increased blood pH (alkalosis) --> more calcium binding to albumin and other proteins, reduces the amount of free calcium available in the blood

metabolic alkalosis diagnostic findings

ABG

urine chloride levels to differentiate between the types of metabolic alkalosis

metabolic alkalosis treatment

fix problem, fluid replacement, monitor potassium levels, proton pump inhibitors (to reduce acid lost from the stomach)

respiratory acidosis clinical manifestations

Elevated PaCO2 (hypercapnia) > 45 mm Hg

Tachypnea

confusion

decreased LOC

Tachycardia

Hypertension

Arrhythmias

Increased ICP

Hyperkalemia

Cyanosis

respiratory acidosis diagnostic findings

ABG

serum electrolyte levels

chest xray

drug screen

ECG monitoring

respiratory acidosis treatment

goal is improve ventilation and treat underlying cause

Bronchodilators

Antibiotics

Thrombolytics or anticoagulants

Nebulizers

Adequate hydration

Mechanical ventilation

normal PaO2 levels

80-100mmHg

respiratory alkalosis causes

Anxiety

Panic disorder

Hypoxemia

Salicylate intoxication

Inappropriate ventilator settings

respiratory alkalosis clinical manifestations

Lightheadedness

Numbness and tingling

Tinnitus

LOC

Tachycardia

Arrhythmias

respiratory alkalosis compensation

Kidneys take days to compensate

-If acute: no change in bicarbonate level is seen

-If chronic: bicarbonate level will lower slightly by excreting it through urine