ACID BASE BALANCE NUR 101 - PowerPoint Presentation

Slide1

ACID BASE BALANCE

NUR 101

M.

Gardner

Copyright2/4/2013

Slide2

ACID /BASE BALANCE

In order to meet homeostasis, the body fluids must maintain a stable chemical balance of hydrogen ions in body fluids.

This is done by regulating their acidity /alkalinity.

Deviation from a normal value indicates that the client is experiencing an acid/base imbalance

Slide3

ACID/BASE BALANCE

ACID – substance that releases hydrogen ions (H+)

BASE – accept hydrogen ions in solution

This relationship is measured as

pH.

Slide4

ABG’S

Measurement of ABGs involves analysis of several components:

pH

PCO2

PO2

HCO3

Slide5

ABCS of ABGs

Arterial blood gas analysis

pH – measures the hydrogen ion concentration

it is an indication of the blood’s acidity or alkalinity.

Normal pH of body fluids is 7.35-7.45

pH 7 is neutral

pH <7 is acid, pH >7 is alkaline (base)

acidic----neutral----alkaline

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ABGs

PaCO2/PCO2

35-45mmHg

Carbon dioxide/CO2

Reflects adequate ventilation by the lungs

Hyperventilation occurs PaCO2 <35mmHg. RR/depth increases the more carbon dioxide is exhaled

Hypoventilation occurs PaCO2>45mmHg.

RR/depth decreases, more carbon dioxide is retained – increasing the concentration of CO2

Slide7

ABGs

HCO3 /Bicarbonate

normal range 22-26mE/L

base regulated by the kidneys

the kidneys excrete and retain HCO3 to maintain a normal acid/base balance

is a principal buffer of the ECF compartment

< 22mEq/L – indicates metabolic acidosis

>26meq/L – indicates metabolic alkalosis

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ABGs

PO2 – oxygen in arterial blood

Normal range – 90-100mmHg

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Regulation of Acid/Base Balance

Several body systems are actively involved in maintaining the narrow pH range necessary for optimal function.

This includes

 buffers, respiratory system, renal

system

Buffers

 maintain acid/base balance by neutralizing excess acids/bases

The lungs/kidneys help maintain a normal pH by either excreting/retaining acid/bases.

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BUFFERS

A strong acid added to the ECF causes the bicarbonate to become depleted

 neutralizing the acid  pH drops acidosis

A strong base is added to the ECF, depleting carbonic acid  the pH rises  alkalosis

Buffer reaction is immediate

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Respiratory Regulation

Lungs regulate acid/base balance by eliminating or retaining carbon dioxide (CO2)

Carbon dioxide

 powerful stimulator of the respiratory center

CO2 +H2O=H2CO3  this reaction is reversible

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Renal Regulation

Kidneys kick in by excreting or retaining bicarbonate and hydrogen ions.

Slower to respond to changes

 hour/days to correct imbalances

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Renal Regulation

Excessive hydrogen ions are present and the pH falls (acidosis)

 kidneys reabsorb bicarbonate & excrete hydrogen ions.

With alkalosis and high pH  excess bicarbonate is excreted and hydrogen ions are retained.

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ABG’s –Normal Value

pH 7.35 – 7.45

Pa CO2 35-45 mm Hg

PaO2 80 -100 mm Hg

HCO3 22-26

mEq

/L

O2 Saturation 95-100%

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Acid –Base Imbalances

Are classified as respiratory or metabolic

 considering the general/underlying cause of the disorder.

Respiratory acidosis/alkalosis  retention/excretion of CO2

Bicarbonate /hydrogen levels are regulated by the kidneys, any problems  metabolic acidosis/alkalosis

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Respiratory Acidosis

Client

hypoventilates

CO2 builds up in the bloodstream and the pH drops below normal.

Kidneys try to compensate by conserving bicarbonate  raises the pH

pH <7.35

PaCO2 >45

HCO3 normal or elevated if compensating

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Respiratory Acidosis

Causes:

asthma, COPD

chest wall trauma

sedation medications

Acute lung conditions

Slide18

Respiratory Acidosis

Clinical Manifestations

apprehension

dizziness

muscular twitching

warm flushed skin

lethargy

diminished/absent breath sounds over the affected area

Slide19

Respiratory Acidosis

Interventions

bronchodilator

chest physiotherapy

suction

T,C, &

DB

narcotic antagonist

Slide20

Respiratory Alkalosis

Pt. hyperventilating

 this causes the lungs to blow off CO2

.

ABG

pH > 7.45

pCO2 <35

HCO3 - normal or below 22, if compensating

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Respiratory Alkalosis

Causes

Hyperventilation due to

extreme anxiety

pain

inappropriate mechanical ventilator settings

elevated body temperature

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Respiratory Alkalosis

Clinical Manifestations

increase in rate & depth of respirations

tachycardia

anxious, restlessness

Slide23

Respiratory Alkalosis

Interventions

treat the underlying disorder

allay anxiety – prevent hyperventilation

monitor VS

assist client to breathe in a paper bag

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Metabolic Acidosis

Bicarbonate levels are low in relation to the amount of carbonic acid

 pH low.

ABG

pH is below 7.35

pCO2 normal, if less than 35 may be compensated

HCO3 -- <22

mEq

/L

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Metabolic Acidosis

Causes

starvation

diarrhea

poisoning

diabetes

Slide26

Metabolic Acidosis

Clinical Manifestations

headache

lethargy

confusion

tachypnea

with deep respirations

Slide27

Metabolic Acidosis

Interventions

treat the underlying problem

replace F/E

sodium bicarbonate

–

IV

monitor neurological status

Slide28

Metabolic Alkalosis

Commonly associated with hypokalemia

Increase levels of

bicarbonate

ABG

pH >7.45

pCO2 normal or above 45 if compensating

HCO3 >26

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Metabolic Alkalosis

Cause

Excessive acid loss from the GI tract

Diuretic therapy

Slide30

Metabolic Alkalosis

Clinical manifestations

Slow, shallow respirations

S&S are commonly associated with an underlying condition

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Metabolic Alkalosis

Interventions

monitor

VS

maintain

patent IV access

monitor

I&O

replace

F&E

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ABG Analysis

It is a respiratory problem if the pH and CO2 are traveling in the opposite directions.

pH< 7.35 & CO2 >45 =

Respiratory Acidosis

pH >7.35 & CO2<35 =

Respiratory Alkalosis

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ABG Analysis

It is a metabolic problem if the pH & HCO3 are traveling in the same directions

pH <7.35 and the HCO3 <22 =

Metabolic Acidosis

pH >7.45 and the HCO3>26 =

Metabolic Alkalosis

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Identify the Balance

pH – 7.30

pCO2 – 36mmHg

HCO3 – 14mEq/L

pH – 7.52

pCO2 –

47

mmHg

HCO3 – 43

mEq

/L

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THINK ABOUT THIS

The patient comes to the ER with complaint of vomiting for 3 days. Which acid base imbalance is she at risk for?

The patient has just returned from surgery. He was medicated twice with narcotic analgesics in the PACU. He is difficult to arouse and has a respiratory rate of 12. what acid/base imbalance is he at risk for?

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RELAX

Some day you will know all of this!!!!!!!!