1/9/2009

1

FLUID, ELECTROLYTE

AND

ACID-BASE IMBALANCES

CHAPTER 18

pages 204-222

WATER within the body

• INTRACELLULAR

– Fluid located inside the cell (35-40%)

• EXTRACELLULAR

– Fluid located outside the cell (15-20%)

• Two types of EXTRACELLULAR

• Interstitial: Fluid between cells (10-15%)

• Intravascular: Fluid in the plasma portion

of blood vessels(5%)

Adult fluid averages

• In healthy adults: average

• daily fluid intake is about

• 2500ml/day

• 100ml/kg of 1st 10kg/wt

• 50ml/kg of 2nd 10kg/wt

• 15ml/kg of remaining kg/wt

• Range of 1800-3000

1/9/2009

2

Primary source of body fluid

•Food

•Liquids

Fluid & Electrolyte Regulation

• Normal conditions: these things maintain normal fluid volume & electrolyte concentrations:

– Osmoreceptors: Release of Antidiuretic Hormone (ADH)

– Renin-Angiotensin-Aldosterone System

– Secretion of Atrial Natriuretic Peptide (ANP)

Osmoreceptors

• Definition: neuron that senses serum osmolality

• Serum Osmolality: measurement of the concentration of substances in the blood.

•

• Regulation of fluid volume

• Located: Hypothalmus

1/9/2009

3

Baroreceptors

• Similar to osmoreceptor except it deals

with the blood volume in the heart to

detect changes in blood volume and blood

pressures

• Found in the aortic arch and carotid sinuses

• Definition: Trigger ADH when blood volume

decreases by 10% or BP drops below 90 or

the right atrium is not filling up

RENIN-ANGIOTENSIN-ALDOSTERONE

SYSTEM

• This system is a chain reaction

of chemical being released to increase

both BP and blood volume

• Trigger: juxtaglomerular apparatus

– Ring of cells that surround the arterioles

leading to each glomerulus in the kidney

How does it work?

• Low volume detected…such as blood loss.

• Triggers the juxtaglomerular to release renin

• Renin causes formation of angiotensinogen to angiotensin I and II which causes vasoconstriction and raises BP

• Renin also stimulates the release of aldosteronewhich causes the kidneys to reabsorb sodium causing an increase in blood volume and BP

1/9/2009

4

Aldosterone

• “The most biologically active mineralcorticoid hormone secreted by the adrenal cortex. Aldosterone increases sodium reabsorption by the kidney, thereby indirectly regulation blood levels of potassium, chloride, and bicarbonate, as well as pH, blood volume, and blood pressure”.

Taber’s Cyclopedic Medical Dictionary

Natriuretic Peptides

• Definition: Hormone-like substance that acts opposite of the renin-angiotensin-aldosterone system

• 3 types identified:

– Atrial natriuretic peptide (ANP)

– Brain natriuretic peptide (BNP)

– C-type natriuretic peptide (CNP)

How does it work?

• If there is too much volume… the atrial and ventricular walls will stretch larger than normal…this triggers the peptides and causes the inhibition of the renin-angiotensin-aldosterone system and ADH

• This causes an increase in urine production to get rid of the excess sodium that has been retained .

1/9/2009

5

Fluid & Electrolyte Distribution

• Osmosis

• Filtration

• Diffusion

• Active Transport

Osmosis

• Defined: the movement of

water through a semi-permeable

membrane (one that allows some but

not all substances to pass through)

• Goes from diluted areas to less

diluted areas

Key Terms

• Semi-permeable: Characteristic of cell membranes that permit the passage of some material, but not all….

• Membrane: A thin layer of tissue that lines a tube or cavity, covers an organ or structure, or separates one part from the other.

1/9/2009

6

Filtration

• Defined: moves fluid and some

substances through a semi-permeable

membrane in order to equalize

pressure differences

Diffusion

• Passive: Substances move from

an area of high concentration to

low concentrated area

• Similar to osmosis in that once things

equal out…things remain constant.

Diffusion

• Facilitated: Certain substances

need assistance from a carrier in

order to pass through the

membrane.

• Example: insulin facilitates (carries)

glucose molecules inside cells

1/9/2009

7

Active Transport

• Define: requires adenosine triphosphate (ATP) to move substances from area of low concentration to area of higher concentration

• Exact opposite of passive transport

• Example: potassium-sodium pump

Fluid Imbalances

• Basically…for some reason, fluid in the body is not in the proper place or has the correct volume in the proper place.

»Hypovolemia

»Third-spacing

»Hypervolemia

1/9/2009

8

Hypovolemia

Hypovolemia

• Who’s at risk?

– Lethargic

– Depressed

– Vomiting

– Dementia

– Fever

– Difficulty swallowing

– Diarrhea

– Certain drugs

– Trauma: blood loss

Hypovolemia: Dehydration

• Defined: the volume of body

fluid is lower in all compartments:

intra- and extracellular, electrolytes

and other chemical substances in the

fluid.

1/9/2009

9

Pathophysiology & Etiology

• Fluid loss in excess of fluid intake

• Decrease circulatory volume:

– Increase heart rate

– BP lowers

– Increase respiratory

– Increase temp

S & S: HYPOVOLEMIA

• Earliest: thirst

• VS changes

• Decrease in urine

• Mental status: sleepy

• Dry mouth

• Poor skin turgor

Medical Management: Hypovolemia

• You can replace fluid…

• through IV’s, oral intake,

• blood, etc….

• You have to find the

• underlying cause to

• effectively treat and

• stop Hypovolemia

1/9/2009

10

Nursing Management: Hypovolemia

• Assess

• Make a plan

• Evaluate the outcomes

• Teach, Teach, Teach

Hypervolemia

Pathophysiology & Etiology

• Fluid intake greater than fluid loss

•Excessive oral intake

•Rapid IV infusion

•Heart failure

•Kidney disease

1/9/2009

11

Hypervolemia

• Pitting edema: indentation in

the skin after compression. Usually

not seen until 3L excess in volume.

S & S: Hypervolemia

• Weight gain

• Elevated BP

• Increased breathing effort

• Edema

• Marks on the skin from socks, rings, etc.

• Congestion in the lungs

Medical Management

• Find underlying cause of excess

fluid

• Restrict fluid

intake

• Diuretics

• Limit salt/sodium

• intake

1/9/2009

12

Nursing Management

•Assess

•Make a plan

•Evaluate the outcomes

•Teach, Teach, Teach

Third Spacing

• Defined: Fluid leaves

• its normal areas and moves out into the tissue

– Low level of

– albumin

– Severe burns

– Severe allergic

– reactions

S & S: Third Spacing

• S & S hypovolemia without the

weight loss.

1/9/2009

13

Medical Management

• Restore circulatory volume

• Albumin: helps restore osmotic pressure:

which then allows trapped fluid to be

pulled back into intravascular space.

• Most physicians will order a diuretic with

albumin to stop hypervolemia when the

fluid is back where it should be.

Nursing Management

•Assess

•Make a plan

•Evaluate the outcomes

•Teach, Teach, Teach

Electrolyte Imbalances

• Sodium

• Potassium

• Calcium

• Magnesium

1/9/2009

14

Sodium Imbalances

• Normal levels 135-145mEq/L

• Found in extracellular fluid

• Maintains nerve and muscle

activity

• Regulates and distributes fluid

throughout the body

HYPONATREMIA

• Loss of sodium

– Diaphoresis

– Excessive water drinking

– Non-electrolyte IV fluid

– Diuresis

– Vomiting/GI suctioning

– Addison’s Disease

HYPONATREMIA

• S & S:

– Confusion

– Weakness

– Tachycardia

– Temperature

– Anorexia

– N/V

Severe S & S:

convulsions/coma

1/9/2009

15

HYPERNATREMIA

• Excessive amount of sodium

in the blood

• Watery diarrhea

• More salt than water intake

• High fever

• Severe burns

• Decrease water intake

HYPERNATREMIA

• S & S:

– Thirst

– Dry mucous

membranes

– Low output

– Fever

– Dry tongue

– Lethargy

POTASSIUM IMBALANCES

• Main electrolyte (CATION)

found in intracellular fluid

• Potassium works similar to

sodium, except inside the cells

1/9/2009

16

HYPOKALEMIA

• Loss of potassium (K+)

– Diuretics

– N/V/D

– Corticosteroids

– IV insulin/glucose

– IV nutrition (if K+ not added in)

HYPOKALEMIA

• S & S– Fatigue/weakness

– Leg cramps

– Dysrhythmias

– N/V

Severe S & S

hypotension, cardiac or respiratory arrest, death

HYPOKALEMIA

• Treatment:

– Mild: K+ rich foods or oral K+

– Severe: IV K+ administration

1/9/2009

17

HYPERKALEMIA

• Excess in potassium levels

• Renal failure

• Severe burns

• Overuse of K+

• Crushing injuries

HYPERKALEMIA

• S & S:

– N/V/D

– Weakness

– Cardiac dysrhythmias

HYPERKALEMIA

• Treatment:

– Mild:

• avoidance of K+ rich foods

– Severe:

• IV insulin/glucose combo

• Kayexalate

• Dialysis

1/9/2009

18

CALCIUM IMBALANCES

• Most calcium is found in bone

and teeth

• Only about 1% in blood: needed

for blood clotting

cardiac muscle

nerve impulses

HYPOCALCEMIA

• Low calcium level

– Vit D deficiency

– Thyroid disease

– Severe burns

– Pancreatitis

– Medications

– Abdominal problems

– Rapid administration of blood

HYPOCALCEMIA

• S & S:

– Tingling to extremities

– Tingling to the mouth area

– Muscle/abd. Cramping

– Muscle twitching

Severe:

laryngeal spasm, bleeding, dysrhythmias

1/9/2009

19

HYPOCALCEMIA

• Treatment:

–Mild:

• Oral calcium

• Vitamin D

–Severe:

• IV Calcium

HYPERCALCEMIA

• Excess calcium

–Parathyroid gland tumors

–Multiple fractures

–Paget’s Disease

–Immobilization

–Chemo/CA

HYPERCALCEMIA

• S & S:

–Deep bone pain

–Constipation

–N/V

–Fractures

–Mental changes

–Kidney stones

1/9/2009

20

HYPERCALCEMIA

• Treatment:

– Mild:

• Increase fluid intake

• Limiting calcium consumption

– Severe:

• IV NS

• Diuretics

• Meds. that help regulate calcium levels

• If CA present, treated on individual basis

MAGNESIUM IMBALANCES

• Found in bone, heart, liver, and

skeletal muscle cells

• Nerve impulses

• Muscle excitability

• Helps with Vit B

functioning

HYPOMAGNESEMIA

• Loss of magnesium

–ETOH abuse

–Diabetic ketoacidosis

–Kidney disease

–Severe burns

–Malnutrition

–Gastric problems

1/9/2009

21

HYPOMAGNESEMIA

• S & S:

– Tachycardia

– Dysrhythmias

– Neuro. Irritability

– Leg cramps

– Hypertension

– Dysphagia

– Seizures

HYPOMAGNESEMIA

• Treatment:

– Mild:

• Food rich in magnesium

• Oral supplement of magnesium

– Severe:

• IV magnesium sulfate

HYPERMAGNESEMIA

• Excess of magnesium

– Renal failure

– Addison’s disease

– Antacids/laxatives

– Thyroid disease

1/9/2009

22

HYPERMAGNESEMIA

• S & S:

–Flushing

–Hypotension

–Lethargy

–Bradycardia

–Depressed respirations

–coma

HYPERMAGNESEMIA

• Treatment:

–Mild:

•Stop oral administration

–Severe:

•Hemodialysis

•Mechanical ventilation

ACID-BASE BALANCE

• Acids and bases are also found in

body fluid

– Example ACID: H2CO3 Carbonic acid

– Example BASE: HCO3 Bicarbonate

Acid/base influences the pH of body fluid

Normal pH: 7.35-7.45

Below 7.35: acidosis

Above 7.45 alkalosis

1/9/2009

23

ACID-BASE BALANCE

• The pH is regulated by:

– Chemical Regulation

• Buffer systems: adding hydrogen causes

acididty…taking away hydrogen ions causes

alkalinity.

– Oxygen Regulation

• Lungs regulate the amount of CO2 stored to

regulate pH (CO2 part of carbonic acid)

• Kidneys regulate the amount of bicarb.

excreted or stored in the body (alkaline)

ACID-BASE IMBALANCES

• Life-threatening

• Death occurs quickly if less than

6.8 (acidic) or greater than 8.0

(alkalotic)

• ABG’s measure pH and acid/base

components found in the blood

ACID-BASE IMBALANCES

• Types of imbalances:

–Acidosis

• Metabolic

• Respiratory

–Alkalosis

• Metabolic

• Respiratory

1/9/2009

24

METABOLIC ACIDOSIS

• Define: decrease in pH

because of an increase in acids

other than carbonic acid

• Decrease in oxygen to cells that

result in anearobic metabolism:

producing lactic acid.

METABOLIC ACIDOSIS

• S & S:

– Deep, rapid breathing (Kussmaul’s)

– Anorexia

– N/V

– Weakness

– Confusion

– Cardiac problems

– Coma and death

METABOLIC ACIDOSIS

• Diagnosis:

–↓pH initially

–↓HCO3

–Normal PaCO2

1/9/2009

25

METABOLIC ACIDOSIS

• The initial response from the body is to try to change the balance to compensate for the imbalance

• Partial compensation: deep breathing will burn off CO2 and ↓ to try to normalize the pH…

– pH is still ↓

– HCO3 is ↓

– Now the PaCO2 is ↓

METABOLIC ACIDOSIS

• The body will continue this trend until the pH returns to normal

• This is considered full compensation

– pH normal

– HCO3 ↓

– PaCO2 ↓

If the body is healthy enough, it can maintain this for a long period…until the problem is found and corrected…if not corrected…the body will begin to decompensate and the problem returns

METABOLIC ALKALOSIS

• Defined: increase in pH because

of additional bicarb. or decrease

in hydrogen

• Overuse of alkalitic drugs

• Diuretic therapy

• Vomiting

• Hypokalemia

1/9/2009

26

METABOLIC ALKALOSIS

• S & S

– Anorexia

– N/V

– Circumoral paresthesias

– Confusion

– Spasm and reflex problems

– ↓ resp. rate

METABOLIC ALKALOSIS

• Initial:

– ↑ pH

– ↑ HCO3

– Normal PaCO2

– Again, the respiratory regulator kicks in and tries to normalize the pH by using slower and more shallow breathing to retain CO2 compensation begins.

METABOLIC ALKALOSIS

• Partial Compensation:

– ↑ pH

– ↑ HCO3

– ↑ PaCO2

• Compensation:

– ↑ pH (but usually lower)

– ↑ HCO3 (lower)

– ↑ Pa CO2

1/9/2009

27

RESPIRATORY ACIDOSIS

• Defined: excess in carbonic acid which

decreases the pH

• Resp. problems cause this:

– Pneumothorax/hemothorax

– Pulmonary edema

– COPD

Things that cause the lungs to retain

carbon dioxide CO2

RESPIRATORY ACIDOSIS

• Initial:

– ↓ pH

– Normal HCO3

– ↑ PaCO2

This time the kidneys go to work…they try

to absorb more of the HCO3 in an

attempt to balance out the increase in

PaCO2…this can take 2-3 days.

RESPIRATORY ACIDOSIS

• Partial compensation:

– ↓ pH

– ↑ HCO3

– ↑ PaCO2

• Compensation:

– Normal pH

– ↑ HCO3

– ↑ PaCO2

1/9/2009

28

RESPIRATORY ACIDOSIS

• Treatment:

– Have to find underlying cause and

treat

– May need to mechanically ventilate

– May need to add IV sodium bicarb

– Need to maintain airway and keep

secretions to a minimum

RESPIRATORY ALKALOSIS

• Define: Rapid breathing causes an

increased release of carbonic acid

with expiration (Hyperventilating)

– Anxiety

– High fever over long period

– Thyroid problems

– Aspirin poisoning

– ventilators

RESPIRATORY ALKALOSIS

• S & S

–Increased resp. rate

–Feeling faint

–Tingling

–Sweating

–Dry mouth

–Severe: convulsions

1/9/2009

29

RESPIRATORY ALKALOSIS

• Initial:

– ↑ pH (High normal)

– Normal HCO3

– ↓ PaCO2

– Again, the kidneys kick in and try to

normalize the balance by excreting HCO3

and trying to balance the pH

RESPIRATORY ALKALOSIS

• Partial compensation:

– Normal high pH

– ↓ HCO3

– ↓ PaCO2

• Compensation:

– Normal pH

– ↓ HCO3

– ↓ PaCO2