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Unit III: Basic Nursing Concepts

Lecture I: Fluids and Electrolytes

Lecture II: Acid-Base Balance and Imbalance

Dr Naiema Gaber

Fundamentals of Nursing II2nd year

Fluid and Electrolyte

Objectives Explain homeostasisExplain homeostasis Discuss homeodynamics of Discuss homeodynamics of

1-Water Balance (ECF/ICF volumes)1-Water Balance (ECF/ICF volumes)

2-Electrolyte Balance (Na+ and K+)

Identify nursing interventions for clients Identify nursing interventions for clients

with altered fluids and electrolytes with altered fluids and electrolytes

balancebalance.

Fluids

– Substances composed of freely moving molecules

– Have the ability to conform to the shape of the container that holds it

– There are different types of fluids in our bodies

What is homeostasis?

It is physiologic processes that regulate fluids intake & output as well as movement of water & substances dissolved in it (fluids)between the body compartments

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What are the factors that influence body fluids?

The body fluid composition of tissue varies by

– Tissue type (lean tissues have higher

fluid content than fat tissues)

– Gender (males have more lean tissue and therefore more body fluid)

– Age (lean tissue is lost with age and body fluid is lost with it)

Water is essential for life, HOW???

Water is vital to health and normal cellular function as it is a

medium for metabolic reactions within cells. transporter for nutrients and waste products. lubricant. Help in regulating and maintaining body

temperature.

60% of the average healthy adult’s weight is water

Major Compartments for Fluids(Distribution of body fluids)

INTRACELLULAR FLUID (ICF 63% of fluids)

Inside cell Most of body fluid

(40% weight) Decreased in

elderly

EXTRACELLULAR FLUID ECF (37 % of fluids is Outside cell)

Intravascular fluid - within blood vessels (5%)

Interstitial fluid - between cells & blood vessels (15%)

Trancellular fluid - cerebrospinal, pericardial , synovial

Fluids

Figure 7.1a

Fluids

Figure 7.1c

Distribution of body fluids

Fluids

Extracellular fluids include– Tissue fluid found between the cells within

tissues and organs of the body (interstitial)– Plasma, the fluid portion of blood that carries the

blood cells (intravascular) – Trans-cellular fluid - cerebrospinal, pericardial ,

synovial

Electrolytes

Body fluid is composed of– Electrolytes which are mineral salts dissolved in

water, including for example:» Sodium

» Potassium

» Chloride

» Phosphorus

What is meant by ELECTROLYTES?

*Substance when dissolved in body fluids charged ions & is able to carry an electrical current conducting electricity.

* It can be: CATION - positively charged electrolyte ANION - negatively charged electrolyte

*No. Cations = No. Anions for homeostasis

*Commonly measured in milliequivalents / liter (mEq/L)

WHAT IS THE IMPORTANCE OF ELECTROLYTES

Maintaining fluids balanceContributing to acid-base

regulationFacilitating enzyme reactionTransmitting neuromuscular

reactions

MILLIEQUIVALENT (mEq)

Unit of measure for an electrolyte Describes electrolyte’s ability to combine

& form other compounds Equivalent weight is amount of one

electrolyte that will react with a given amount of hydrogen

1 mEq of any cation will react with 1 mEq of an anion

DEFINITIONS

SOLUTE - substance dissolved SOLVENT - solution in which the solute is

dissolved SELECTIVELY PERMEABLE

MEMBRANES - found throughout body cell membranes & capillary walls; allow water & some solutes to pass through them freely

Movement of Body Fluids and Electrolytes

It can be by:

Osmosis?

Diffusion?

Filtration?

Active

transport

METHODS OF FLUID & ELECTROLYTE MOVEMENT

1- Passive Transport Diffusion Osmosis Filtration

2- Active Transport

using energy (ATP)

DIFFUSION

Process by which a solute ( ions and molecules) in solution moves as gas or substance

Molecules move from an area of higher concentration to an area of lower concentration to evenly distribute the solute in the solution

It can be simple or facilitated diffusion

FACILITATED DIFFUSION

Involves carrier system that moves substance across a membrane with simple diffusion , (from area of higher concentration to one of lower concentration)

Example is movement of glucose with assistance of insulin across cell membrane into cell

OSMOSIS

Movement of the solution =solvent = water across a membrane to equalizes the concentration of ions (solute)on each side of membrane

Movement of solvent molecules across a membrane to an area where there is a higher concentration of solute that cannot pass through the membrane

Osmosis

Figure 7.4

OSMOSIS

OSMOSIS cont.

OSMOTIC PRESSURE

Pull that draws solvent through the membrane to the more concentrated side (or side with solute )

It is determined by relative number of particles of solute on side of greater concentration

COLLOID OSMOTIC PRESSURE OR ONCOTIC PRESSURE

Special kind of osmotic pressure Created by substances with a high molecular weight (like albumin)

ISOTONIC

ISO - means alike TONICITY - refers to osmotic activity of body

fluids; tells the extent that fluid will allow movement of water in & out cell

Means that solutions on both sides of selectively permeable membrane have established equilibrium

Any solution put into body with the same osmolality as blood plasma.

ISOTONIC SOLUTIONS

EXAMPLES: 0.9% sodium chloride solution 5% glucose Ringer’s Solution Lactated Ringer’s Solution

HYPOTONIC HYPERTONIC

Solution of lower osmotic pressure

Less salt or more water than isotonic

If infused into blood, RBCs draw water into cells ( can swell & burst )

Solutions move into cells causing them to enlarge

Solution of higher osmotic pressure

3% sodium chloride is example

If infused into blood, water moves out of cells & into solution (cells wrinkle or shrivel)

Solutions pull fluid from cells

HYPOTONIC SOLUTIONS

5% DEXTROSE & WATER

0.45% SODIUM CHLORIDE

0.33% SODIUM CHLORIDE

HYPERTONIC SOLUTIONS

3% SODIUM CHLORIDE 5% SODIUM CHLORIDE WHOLE BLOOD ALBUMIN TOTAL PARENTERAL

NUTRITION TUBE FEEDINGS CONCENTRATED

DEXTROSE (>10%)

OSMOLALITY

Measure of solution’s ability to create osmotic pressure & thus affect movement of water (tonicity)

Number of osmotically active particles per kilogram of water

Plasma osmolality is 280-300* mOsm/ kg ECF osmolality is determined by sodium MEASURE used in clinical practice to evaluate

serum & urine

IV Fluid Tonicity !!!!

TONICITY Hypotonic Isotonic Hypertonic

OSMOLALITY CELL < 270 mOsm/kg Swelling 275-295 mOsm/kg Nothing > 300 mOsm/kg Shrinking

Osmolality In Clinical Practice *

Serum 280-300mOsm/kg Urine 50-1400mOsm/kg Serum osmolality can be estimated by

doubling serum sodium Urine specific gravity measures the kidneys’

ability to excrete or conserve water

Osmolality In Clinical Practice *

BUN - blood urea nitrogen; made up of urea an end-product of protein metabolism.

inc. with protein intake, fever, & sepsis; dec. with starvation, end-stage liver

dx., low protein diet, expanded fluid vol. (as with pregnancy)

Osmolality In Clinical Practice *

Creatinine - end product of muscle metabolism; better indicator of renal function; normal level 0.7-1.5 mg/d L

Hematocrit - vol. % of RBCs in whole blood; normal level in male- 44-52%

In female- 39-47%

FILTRATION

Movement of fluid and solutes together through a selectively permeable membrane from an area of higher hydrostatic pressure to an area of lower hydrostatic pressure

Arterial end of capillary has hydrostatic pressure > than osmotic pressure so fluid & diffusible solutes move out of capillary

HYDROSTATIC PRESSURE

Force of the fluid pressing outward against vessel wall

With blood not only refers to weight of fluid against capillary wall but to force with which blood is propelled with heartbeat

“Fluid- pushing pressure inside a capillary”*

ACTIVE TRANSPORT SYSTEM

Moves molecules or ions uphill against concentration & osmotic pressure

Requires specific “carrier” molecule as well as specific enzyme (ATP)

Hydrolysis of adenosine triphosphate (ATP) provides energy needed

Sodium-potassium pump is an active transport system. It moves substances from area of low solutes concentration to a higher one

REMEMBER

DEFUSION MOVEMENT OF SOLUTE ONLY (SUBSTANCE)

OSMOSIS MOVEMENT OF SOLVENT ((SOLUTION OR WATER

ONLY

FELTERATION MOVEMENT OF BOTH SOLUT AND SOLVENT from area of higher hydrostatic pressure to lower one

ACTIVE TRANSPORT MOVEMENT OF ION OR MOLECULES AGAINST CONCENTRATION OR OSMOTIC PREASSURE

Regulating Body Fluids

I- Fluid intake:

In health by: Drinking Eating

 In illness by: Parenteral route (IV – SC) Enteral feeding (in the stomach or intestine)

II- Fluid output:

Organs of fluids loss:

Skin

Lungs

G I T

Kidney

Homeostatic Mechanisms

Kidneys: The kidneys are functioning under the mastering of

aldosterone and antidiuretic hormone (ADH). Regulate electrolytes levels in the ECF by selective

retention of needed substances and excretion of unneeded substances.

Regulate pH of ECF by excretion or retention of hydrogen ions.

Heart and Blood Vessels: If pumping action of the heart fails, it will interfere

with the renal perfusion and thus water and electrolytes regulation.

 

Homeostatic Mechanisms cont.

Lungs:Remove 300 ml of water daily.Cough will ↑ the loss of water.Mechanical ventilation + excessive moisture ↓ loss.

 

Parathyroid Gland:

Parathyroid gland secretes parathyroid hormone:

• It regulates calcium and phosphate balance.

• It influences Ca++ reabsorption from interstitial and renal tubules

Pituitary Gland:•Hypothalamus manufactures antidiuretic hormone (ADH) which is stored in the pituitary gland as needed for the maintenance of osmotic pressure of the cells by controlling renal water retention or excretion and control blood volume. Adrenal Gland:Adrenal gland secretes aldosterone •↑ Secretion of aldosterone → sodium retention → water retention → potassium loss.•↓ Secretion of aldosterone → sodium loss→ water loss→ potassium retention.

Homeostatic Mechanisms cont.

INTAKE FLUIDS OUT

Ingested liquids 1500 Water in foods 800* Water from oxidation

300*

TOTAL 2600*

INSENSIBLE Skin 600* Lungs through expired

air 300* Feces 200 Kidneys 1500* TOTAL 2600*

INTAKE & OUTPUT

INTAKE Oral fluids - including

ice, gelatin, etc. Parenteral fluids Tube feedings with

flushes Catheter irrigants that

are not withdrawn

OUTPUT Urine output Liquid feces Vomitus NG drainage Excessive sweating Wound drainage Draining fistula Rapid or labored RR

Quiz ????

1. Who has the highest body % of water? Infant? Adolescent? 50 year old? Elderly?

2. The chief cation of the ICF is Sodium? Chloride? Potassium? Phosphorus

More Questions ????

4. If you don’t drink any water or have lost a lot of water, what do you think will happen to: renal blood flow, renal BP, Glomerular filtration rate (GFR), ADH, Urine output

5. Your patient’s blood volume is low due to hemorrhage. What do you expect to see with: BP ? HR ? Skin hot or cool ? Urine output ?

You just ate 4 bags of potato chips so what would you expect?

THIRST ? ADH ? OSMOLALITY ? ALDOSTERONE ? URINE OUTPUT ?

You decide to drink 5 gallons of water so what do you expect ?

THIRST ? ADH ? OSMOLALITY ? BLOOD VOLUME ? RENAL BLOOD

VOLUME ? URINE OUTPUT ?

Fluids Disturbances

1. ECF deficit → both Na+ and water loss (hypovolemia or dehydration).

In the strict sense dehydration is not an ECF deficit but water deficit only.

2. ECF excess → both Na+ and water retention (hypervolemia or edema).

Over hydration is an ↑ only in the amount of water only not electrolytes.

Assessment of Fluid Balance

Health History Daily Weight Thirst Intake and Output Vital Signs Skin Turgor Mucous Membranes Hand Vein Filling/Emptying Labs – Urine SG; H&H; Sodium; Total Protein;

Albumin; Serum Osmolality; BUN; Creatinine

THIRST

Conscious desire for water Major factor that determines fluid intake Initiated by the osmoreceptors in

hypothalamus that are stimulated by increase in osmotic pressure of body fluids to initiate thirst

Also stimulated by a decrease in the ECF volume

FLUID VOLUME DEFICIT (FVD

Hypovolemia or FVD is result of water & electrolyte loss

Compensatory mechanisms include: Increased sympathetic nervous system stimulation with an increase in heart rate & cardiac contraction; thirst; plus release of ADH & aldosterone

Severe case may result in hypovolemic shock or prolonged case may cause renal failure

CAUSES OF FVD

Abnormal GI fluid loss such as N&V or drainage of GI tract

Abnormal fluid loss from skin such as high temperature or burns

Increased water vapor from the lungs such as hyperpnea

Conditions that increase renal excretion of fluids such as diuretics & hypersomolar tube feedings

Decrease in fluid intake Third-space shift such

as ascites or trauma

LAB VALUES IN FVD

INCREASE IN: HEMATOCRIT nl 44*-52*% M nl 39*-47% F BUN nl 10*-20 mg/dl URINE SPECIFIC GRAVITY nl 1.010*-1.025*

SIGNS & SYMPTOMS OF FVD

Dry mucous membranes Weight loss Orthostatic hypotension & tachycardia Subnormal Body temperature Flat neck veins & decrease in CVP Decreased urinary output & altered

sensorium

NURSING MANAGEMEMT OF FVD

Monitoring I&O on a regular schedule depending on the patient

If urine output is below 30 mL / hr. notify the physician

May check urine specific gravity q 8hrs. Weigh patient daily at the same time & recognize

that a change of 2.2 lbs. represents a loss of 1000 mL

Monitor skin turgor, oral membranes, lab

Dehydration !!!!

Water isn’t replaced in body Fluid shifts from cells to EC space Cells lose water Happens in confused, comatose, bedridden

persons along with infants & elderly May be treated with hypotonic sol (like

dextrose 5% in water)

Dehydration cont.

Risk Factors (Causes) Insufficient intake due to anorexia, nausea, impaired swallowing,

confusion, depression.

Loss of water and electrolytes from: vomiting, diarrhea, nasogastric suction, excessive sweating, fever, polyuria, abdominal drainage, or wound losses.

Nursing intervention in dehydration

Oral fluid is given at frequent intervals in a small amount.

Replace the lost electrolyte. Frequent mouth care. Replace fluids by enteral or parenteral route

if oral replacement can not tolerate. Prevent skin breakdown.

FLUID VOLUME EXCESS FVE

FVE is a result of expansion of fluid compartment due to increase in total sodium content .

Fluid excess in the intravascular space is called hypervolemia.

Fluid excess in interstitial space is called edema Excess of extra cellular fluid in other body

compartment Third space is called. Fluids may be trapped in abdomen, peritoneum (ascites) or plural space (plural effusion).

SIGNS & SYMPTOMS OF FVE

SOB & orthopnea Edema & weight gain Distended neck veins & tachycardia Increased blood pressure Crackles & wheezes May be ascites & pleural effusion Increase in CVP

NURSING MANAGEMENT OF FVE

Monitor I & O plus monitor for physical signs of hypervolemia

Check for edema & weigh patient daily Restrict sodium intake as prescribed Limit intake of fluids Watch for signs of potassium imbalance Monitor for signs of pulmonary edema Place patient in semi-Fowler’s position

Nursing management in edema

Assessment: Measure intake and output at regular

intervals. Assess breath sound. Monitor degree of edema at the most

dependent parts of the body. Assess the degree of pitting edema.

EDAEMA

It is excessive accumulation of fluid isn the interstitial space it may be

localized edema if it due to trauma or inflammation.

Generalized edema involves the whole body. It is severe.

Pitting edema on the leg Pitting edema on the foot

Pitting odema

Water Intoxication !!!!

Excess fluid moves from EC space to IC space Happens with SIADH, rapid infusion of

hypotonic IV sol or tap water as NG irrigant or enemas; can happen with psychogenic polydipsia ( may drink 12-18 L/day )

Findings Serum NA < 125 mEq/L Serum Osmolality < 280 mOsm/kg

Electrolyte Imbalances

1. Sodium– Hyponatremia– Hypernatremia

2. Potassium– Hypokalemia– Hyperkalemia

3. Calcium– Hypocalcemia– Hyperc alcemia

4. Magnesium– Hypomagnesemia– Hypermagnesemia

5. Phosphorus– Hypophosphatemia– Hyperphosphatemia

SODIUM (NA+)

DOMINANT EXTRACELLULAR ELECTROLYTE

CHIEF BASE OF BLOOD

NL SERUM LEVEL 135-145 mEq/L

SODIUM (NA)*

Main extracellular fluid (ECF) cation Helps govern normal ECF osmolality Helps maintain acid-base balance Activates nerve & muscle cells Influences water distribution (with

chloride)

SODIUM (NA+)

SODIUM AFFECTS FLUID VOLUME & CONCENTRATION IN ECF

IS REGULATED BY: Aldosterone Renal blood flow Renin secretion Antidiuretic hormone (ADH) due to its effect on water Estrogen

Carbonic anhydrase enzyme

HYPERNATREMIA

Serum Na + level > 148 mEq/L serum osmolality > 295 mOsm/kg & urine sp gr > 1.030 with nl kidneys

Collaborative management tries to gradually lower serum sodium by *infusion of 0.45% NaCl *monitoring U/O & serum sodium level *administering fluids carefully

* restricting sodium intake The thirsty person will not get this !!!!

Memory Jogger Hypernatremia

S - skin flushed A - agitation L - low grade fever T - thirst

Nursing Diagnosis in Hypernatremia

Fluid volume deficit r/t abnormal water loss, inadequate water intake

Fluid volume excess r/t excessive intake of salt, abnormal Na retention

Risk for injury r/t restlessness and agitation

Impaired oral mucous membrane r/t decreased salivation

Risk for aspiration r/t stupor

HYPONATREMIA

Serum Na+ < 135 mEq/L (patient may be asymptomatic until level drops below 125)

Collaborative management seeks to correct cause & give sodium with caution due to possible rebound fluid excess by :*infusing isotonic saline in IV fluids*restricting oral & IV water intake*increasing dietary sodium *monitoring for signs of hypervolemia

Nursing diagnosis of Hyponatremia

Fluid volume excess r/t water intoxication, SIADH

Knowledge deficit r/t specific need to replace Na

Risk for injury r/t confusion, weakness, seizures

POTASSIUM (K+)

DOMINANT INTRACELLULAR ELECTROLYTE

PRIMARY BUFFER IN CELL

NL SERUM LEVEL 3.5-5.5 *mEq/L

POTASSIUM (K)*

Dominant cation in intracellular fluid (ICF) Regulates cell excitability Permeates cell membranes, thereby

affecting cell’s electrical status Helps control ICF osmolality & ICF

osmotic pressure

POTASSIUM (K+)

MOVEMENT INFLUENCED BY:Changes in pH Insulin

Adrenal hormones Changes in serum sodium

IMPORTANT IN: Neuromuscular irritabilityIntracellular osmotic activity Acid-base

balance

HYPERKALEMIA

K+ > 5.5 mEq/L Dangerous due to potential for fatal dysrhythmias,

cardiac arrest Major cause is renal disease EKG shows tall, peaked T waves &

dysrthythmias Beware of pseudohyperkalemia due to prolonged

tourniquet, hemolysis of blood, sampling above KCl infusion

Nursing diagnosis in Hyperkalemia

Risk for injury r/t lower extremity weakness, possible seizures

Activity intolerance r/t neuromuscular weakness

Risk for decreased cardiac output r/t dysrhythmia and cardiac conduction changes

HYPERKALEMIA TX

Watch EKG for fatal dysrthymias or cardiac arrest Collaborative management may include:

Calcium to counteract effect on heartSodium bicarbonate to alkalinize fluidsHemodialysis or peritoneal dialysis Cation exchange resins (Kayexalate) by mouth or enema

Small dose of insulin & dextrose Restrict dietary K+

www.peditips.com 101

HYPOKALEMIA

K+ < 3.5mEq/L Most common type of electrolyte imbalance Major cause is increase renal loss most often

associated with diuretics EKG shows dysrhythmias, flattened T wave Can increase the action of digitalis NEVER GIVE K+ IV PUSH & ALWAYS

DILUTE IN IV FLUIDS

Memory Jogger Hypokalemia

S - skeletal muscle weakness U - U wave (ECG changes) C - constipation, ileus T - toxicity of digitalis glycosides I - irregular, weak pulse O - orthostatic hypotension N - numbness

Nursing diagnosis in hypokalemia

Altered nutrition, less than body requirements

Risk for injury, vessels, tissues, GI track Altered urinary elimination of K+ Risk for decreased C.O. r/t dysrhythmia

from electrolyte imbalance, cardiac arrest

HYPOKALEMIA TX

Correct the cause Oral or IV administration of potassium Salt substitutes containing K+

Foods high in potassium : bananas, pears, dried apricots; fruit juices; tea, cola beverages; milk; meat, fish; baked potato; dried beans (cooked); ANYTHING THAT TASTES GOOD LIKE CHOCOLATE !!

www.peditips.com 106

Summary of the lecture

Fluids represent 60 % of weight Distributed as

INTRACELLULAR FLUID (ICF 63% of fluids)

Inside cell Most of body fluid

here - 40% weight Decreased in elderly

EXTRACELLULAR FLUID ECF (37 % of fluids is Outside cell)

Intravascular fluid - within blood vessels (5%)

Interstitial fluid - between cells & blood vessels (15%)

Transcellular fluid - cerebrospinal, pericardial , synovial

Electrolytes

Body fluid is composed of– Water– Electrolytes: mineral salts dissolved in water,

including» Sodium

» Potassium

» Chloride

» Phosphorus

Movement of Body Fluids and Electrolytes

It can be by:

Osmosis?

Diffusion?

Filtration?

Active

transport

IV Fluid Tonicity !!!!

TONICITY Hypotonic Isotonic Hypertonic

OSMOLALITY CELL < 270 mOsm/kg Swelling 275-295 mOsm/kg Nothing > 300 mOsm/kg Shrinking

Fluids Disturbances

1. ECF deficit → both Na+ and water loss (hypovolemia or dehydration).

In the strict sense dehydration is not an ECF deficit but water deficit only.

2. ECF excess → both Na+ and water retention (hypervolemia or edema).

Over hydration is an ↑ only in the amount of water only not electrolytes.

Electrolyte Imbalances

1. Sodium– Hyponatremia– Hypernatremia

2. Potassium– Hypokalemia– Hyperkalemia

3. Calcium– Hypocalcemia– Hyperc alcemia

4. Magnesium– Hypomagnesemia– Hypermagnesemia

5. Phosphorus– Hypophosphatemia– Hyperphosphatemia

Patient with hypervolemia should be in which position? – Lying – b- flat– C-Semifowler’s– d-lateral

– (C)

Why we should put patient with hypervolemia in Smi-Fowler’s position bescause he has – a- orthopnea– b-

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UNIT III: BASIC NURSING CONCEPTS

Lecture II:

Acid-Base Balance and Imbalance

Dr Naiema Gaber

Fundamentals of Nursing II2nd year

Acid-Base Balance

Objectives Describing the regulation of acid-base

balance in the body Identifying nursing interventions for

clients with altered acid-base balance.

Which way will the scale tip???*

Acidosis vs. Alkalosis

Definitions

Acid: is a substance that can donate hydrogen ions in solution.

Strong acid such as hydrochloric acid (HCl)release all the H+.

Weak acids like carbonic acid (H2CO3) release some H+.

Base or Alkali: is a substance that can accept hydrogen ions in solution.

Acidity or alkalinity is measured by pH.

Definitions

pH: means the concentration of hydrogen ions [H+] of the solution.

In the body, weak acids and weak bases regulate acid-base balance to prevent sudden changes in the pH of the body fluids.

Normal pH= 7.35 – 7.45. <7.35 = acidosis, >7.45 = alkalosis

ACID-BASE BALANCE

Governed by the regulation of hydrgen ion (H+) concentration in the body

pH = negative logarithm of the H+ concentration

Acids - proton donors & give up H+ Bases - H+ acceptors Acidic - inc. in concentration of H+

Basic - dec. in concentration of H+

HENDERSON - HASSELBALCH EQUATION

Expresses that the ratio of base to acid or HCO3

- to H2CO2 * ( 20: 1) determines the pH

pH < 7.35 ACIDOSIS

pH > 7.45 ALKALOSIS

ACID-BASE REGULATORY MECHANISMS

CHEMICAL BUFFER SYSTEMS - bicarbonate, phosphate, protein, hemoglobin

LUNGS - carbonic acid broken down into CO2 & H2O

KIDNEYS - increasing or decreasing bicarbonate ions

Regulation of Acid-Base Balance Review of definitions

Base – accepts or removes hydrogen ion Buffer- controls the hydrogen ion

concentration:» Absorbing hydrogen ions when an acid is added OR » Releasing hydrogen ions when base is added.

Three Buffer Systems:– Bicarbonate – operates in lungs & kidneys– Phosphate – renal tubules– Protein – Hgb, plasma proteins, & intracellular

protein

I. Buffer mechanisms

1. The bicarbonate buffer system (HCO3-).

important in controlling the pH of extracellular fluids.

2. The phosphate buffer system (HPO4 2- and

H2PO4 -)

important in controlling pH of intracellular fluids

3. The protein buffer system.The largest buffer system inside the cells

II. Respiratory regulation

It controls the rate of CO2 which reacts with water to give carbonic acid which ↑ or ↓ pH of the blood.

III. Renal regulation

The kidney excretes hydrogen ions (H+) and forms bicarbonate ions (HCO3 -) in specific amounts as indicated by the pH of the blood.

Acid – Base Balance

Arterial Blood Gases (ABGs)

pH 7.35-7.45 PaCO2 35-45 mm Hg

Pa O2 80-100 mm Hg

O2 sat. 95-99%

HCO3- 22-26mEq/L

Regulation of Acid-Base Balance

Normal Values:

pHpH PCO2PCO2 HCO3HCO3

7.35 – 7.457.35 – 7.45 35 – 45 mm Hg35 – 45 mm Hg 22 – 26 mEq / L22 – 26 mEq / L

ACID-BASE PARAMETERS

ACID pH <7.35 PaCO2 >45 HCO3 <22

BASE pH >7.45 PaCO2 <35 HCO3 >26

Acid-Base Imbalance

1. Acidosis Respiratory acidosis Metabolic acidosis

2. Alkalosis Respiratory alkalosis Metabolic alkalosis

Respiratory Acidosis*

pH < 7.35 PaCO2 > 45mm Hg

Due to inadequate alveolar ventilation Tx aimed at improving ventilation Respiratory Opposite

Respiratory Alkalosis*

pH > 7.45 PaCO2 < 35mm Hg

Due to alveolar hyperventilation & hypocapnia

Tx depends on underlying cause

Regulation of Acid-Base Balance Respiratory Function

pHpH PC02PC02 ConditionCondition

DecreasedDecreased IncreasedIncreased Respiratory acidosisRespiratory acidosis

IncreasedIncreased DecreasedDecreased Respiratory alkalosisRespiratory alkalosis

Pair Share – Critical Thinking

What acid-base imbalance would you suspect for the patient having respiratory problems with respiratory rate: 28/min and expiratory wheezing?

Pair Share – Critical Thinking

What acid-base imbalance would you suspect for the post-operative patient with respiratory rate 10/min, difficulty to arouse, but arouses with verbal stimuli

Metabolic Acidosis*

pH < 7.35 HCO3 < 22mEq/L

Due to gain of acids or loss of base (like excessive GI loss from diarrhea)

May have associated hyperkalemia Tx aimed at correcting metabolic defect Metabolic Even

Metabolic Alkalosis*

pH > 7.45 HCO3 > 26 mEq/L

Due to loss of acid or gain of base (most common is vomiting or gastric suction)

Hypokalemia may produce alkalosis Tx aimed at underlying disorder

Regulation of Acid-Base BalanceMetabolic Function

pHpH HC03HC03 ConditionCondition

DecreasedDecreased DecreasedDecreased Metabolic acidosisMetabolic acidosis

IncreasedIncreased IncreasedIncreased Metabolic alkalosisMetabolic alkalosis

Regulation of Acid-Base Balance> = increased; < = decreased

ABGABG ConditionCondition Metabolic processMetabolic process

>PCO2>PCO2 MetabolicMetabolic

acidosisacidosis

< HCO3- elimination < HCO3- elimination by the kidneys – by the kidneys – increased acidincreased acid

<PC02<PC02 MetabolicMetabolic

AlkalosisAlkalosis

>HCO3- elimination by >HCO3- elimination by the kidneys –the kidneys –increased baseincreased base

Regulation of Acid-Base Balance Arterial Blood Gas Interpretation

Step 1: Evaluate the pH– pH <7.35 = acidosis– pH >7.45 = alkalosis

Step 2: Evaluate Respiratory Function– Paco2 >45 mm HG = ventilatory failure &

respiratory acidosis– Paco2 <35 mm HG = hyperventilation &

respiratory alkalosis

> = increased; < = decreased

Regulation of Acid-Base Balance Arterial Blood Gas Interpretation

Step 3: Evaluate Metabolic Processes– Serum bicarbonate HCO3 <22 mEq/L = metabolic

acidosis

– Serum bicarbonate HCO3 >26 mEq/L = metabolic alkalosis

Step 4: Determine the Primary Disorder– When Paco2 & HCO3 are both abnormal:

» Determine which follows the deviation from the pH

and

» Deviates the most from normal

Respiratory acidosis

Risk Factors Clinical Manifestation

Nursing Intervention

•Acute lung disease: pneumonia, acute pulmonary edema, aspiration of foreign body…•Chronic lung disease: asthma, cystic fibrosis, emphysema•Overdose of narcotics•Brain injury•Airway obstruction•Chest injury

•Increased pulse•Increased respiratory rate•Headache•Confusion•Convulsions•Warm flushed skin

•Assess respiratory status and lung sound•Monitor air way and ventilation•Inhalation therapy•Percussion and postural drainage•Monitor fluid intake and output•Measure vital signs•Measure arterial blood gases

Respiratory alkalosis

Risk Factors Clinical Manifestation Nursing Intervention

•Hyperventilation due to:-Extreme anxiety-Elevated body temp.-Overventilation-Hypoxia-Salicylate overdose

•Brain energy•Fever•Increased basal metabolic rate

•Shortness of breath•Chest tightness•Numbness and tingling of extrimities•Difficulty concentrating•Blurred vision

•Monitor vital signs and ABGs•Assist client to breath more slowly•Help client breath in a paper bag

Metabolic acidosis

Risk Factors Clinical Manifestation

Nursing Intervention

•Increase of non volatile acids in blood:-renal impairment-DM•Decrease in bicarbonates:-Prolonged diarrhea•Excessive NaCl infusion•Salicylates overdose•Cardiac arrest

•Deep rapid respiration•Lethargy, confusion•Headache•Weakness•Nausea and vomiting

•Monitor ABG values•Monitor intake and output•Monitor of LOC•Administer IV sodium bicarbonate

Metabolic alkalosis

Risk Factors Clinical Manifestation

Nursing Intervention

•Excessive acid base due to:-Vomiting-Gastric suction•Excessive use of K-losing diuiretics•Excessive adrenal corticoid hormones due to:-Cushing’s syndrome-Hyperaldosteronism•Excessive bicarbonate intake from:-Antacids-Parenteral NaHCO3

•Increase respiratory rate and depth•Dizziness•Numbness and tingling of the extremities•Hypertonic muscles, tetany

•Monitor intake and output•Monitor vital signs especially respiration and LOC•Administer IV fluid carefully

EVALUATING ABGs*

1. List pH, PaCO2, & HCO3-

2. Compare to normals & rate as ACID, BASE OR NORMAL. Write A (acid), B (base), or N (normal) or think ROME

3. Circle any two letters that are the SAME to tell IMBALANCE.

pH 7.10 PaCO2 80mmHg HCO3- 25mEq/l ????

IMBALANCE ???? Look at PaO2 & SaO2 for oxygenation

ABG ASSESSMENT*

36 yo pt. complains of acute SOB, R sided pleuritic pain

pH 7.50 PaCO2 29 mmHg

PaO2 60 mmHg

HCO3- 24 mEq/l

SaO2 78%

? Meaning ?

32 yo pt. with drug OD & breathing 5 times / minute

pH 7.25 PaCO2 61 mmHg

PaO2 74 mmHg

HCO3- 26 mEq/l

SaO2 89%

? Meaning ?

ABGs*

70 year old diabetic with hx of not taking insulin

pH 7.26 PaCO2 42

HCO3 17

????

58 year old pt. With CHF for 6 mos. & placed on digoxin & Lasix

pH 7.48 PaCO2 45

HCO3 26

????

Resp Failure – Medical Tx Goals

Maintain adequate oxygenation & ventilation– Oxygen therapy– Mobilization of secretions

» Effective coughing and positioning» Hydration & humidification

– Chest physical therapy– Airway suctioning– Positive pressure ventilation– Relief of bronchospasm– Reduction of airway inflammation– Reduction of pulmonary congestion– Treatment of pulmonary infections– Reduction of severe anxiety, pain, and agitation– Treat underlying cause– Maintain adequate cardiac output– Maintain adequate hemoglobin concentration

Nursing Diagnosis

66-year old man with shortness of breath, dyspnea, orthopnea, 66-year old man with shortness of breath, dyspnea, orthopnea, profuse perspiration, feeling like he can’t catch his breath. You profuse perspiration, feeling like he can’t catch his breath. You observe him to have prolonged expiration.observe him to have prolonged expiration.

Breath soundsBreath sounds: expiratory wheezing – upper lung fields bilaterally; : expiratory wheezing – upper lung fields bilaterally; rhonchi hear in right lung field rhonchi hear in right lung field

ABGsABGs:: Pulse OximetryPulse Oximetry: 89: 89pH -7.28pH -7.28Paco2 – 50Paco2 – 50 B/P: 160/90 HR: 110 Resp: 14 B/P: 160/90 HR: 110 Resp: 14HCO3- - 26HCO3- - 26Pao2 – 66Pao2 – 66

Priority Nsg Actions?Priority Nsg Actions? Top Three Nsg Dx?Top Three Nsg Dx?

Nursing Diagnosis

Ineffective airway clearance Ineffective breathing pattern Risk for imbalanced fluid volume Anxiety Impaired gas exchange Imbalanced nutrition: less than body

requirements