Unit V Acid Base Imbalance.pdf

Unit V Acid Base Imbalance

Tanzeel Ul Rahman Nursing Instructor

BSN, RN, M.Phil Public health

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Objectives

Acid-Base Balance

• An acid is capable of giving up a hydrogen ion

• A base is capable of accepting a hydrogen ion

• Salt and neutralization

– Acids react with bases to form water and salt—neutralization reaction

Maintaining Acid–Base Balance

• Normal plasma pH 7.35 to 7.45: hydrogen ion concentration

• Below 7.25 or above 7.55 is considered life-threatening

• Above 7.8 (alkalosis) or below 6.8 (acidosis) usually is fatal

Three Mechanisms That

Balance pH

• Buffer systems

• Respiratory system

Buffer Systems

• The bicarbonate–carbonic acid buffer system is responsible for more than half of the buffering

• Three other buffer systems in the body include

– Phosphate – Hemoglobin – Protein

Respiratory System

• Because carbon dioxide dissolves in the blood and combines with water to form carbonic acid, retaining or blowing off

carbon dioxide helps retain or eliminate acids from the body

Renal System

• Renal system changes the excretion rate of acids and the regulaion of bicarbonate ion

• The kidneys are slow to compensate, but are the most effective compensating mechanism

Question

What is the most common buffer system in the body?

A. Plasma protein

B. Hemoglobin

C. Phosphate

Answer

D. Bicarbonate–carbonic acid

Rationale: The body’s major extracellular buffer system is the bicarbonate–carbonic acid buffer system, which is assessed when

arterial blood gases are measured.

Arterial Blood Gas Analysis

PaO₂

PaCO₂

pH

SaO₂

HCO₃–

Pa

O

• Partial pressure (P) exerted by oxygen (O₂) in the arterial blood (a)

– Normal value is 80 to 100 mm Hg

– Indicates the amount of oxygen carried in the blood

Pa

CO

• Partial pressure (P) of carbon dioxide (CO₂) in the arterial blood (a)

– Normal value is 35 to 45 mm Hg

pH

• An expression of the extent to which the blood is alkaline or acid

• Normal value is 7.35 to 7.45

Sa

O

• Also abbreviated O₂ Sat

• Percentage of available hemoglobin that is saturated (Sa) with oxygen (O₂)

– For instance, the ratio of the amount of oxygen that is combined with hemoglobin to the total amount of oxygen the hemoglobin can carry

HCO

• The level of plasma bicarbonate

• An indicator of the metabolic acid-base status

• Normal value is 22 to 26 mEq/L

Acidosis and Alkalosis

• Acidosis

– The result of either a loss of base or an accumulation of acid

• Alkalosis

Acid-Base Imbalances

• Metabolic acidosis

• Respiratory acidosis

• Metabolic alkalosis

• Respiratory alkalosis

Metabolic Acidosis

pH

Less than 7.35

PaCO₂

Normal 35–45 mm Hg

HCO₃–

Causes Metabolic Acidosis

• Excessive loss of bicarbonate ions from diarrhea

• Renal failure

• Diabetic ketoacidosis

• Hyperkalemia

• Shock state

Signs and Symptoms Metabolic Acidosis

• Weakness

• Lethargy

• Headache

• Confusion

• Decreased blood pressure

Ketoacidosis

• Vomiting and diarrhea

• Deep rapid breathing (Kussmaul’s respirations)

• May secrete urine with a low pH

• Fruity smell in breath

Treatment Metabolic Acidosis

• Treat Underlying cause

• Insulin and diabetic ketoacidosis

• Dialysis

Treatment Metabolic Acidosis

• With acidosis, hyperkalemia may occur as potassium shifts out of cell

• As acidosis is corrected, potassium shifts back into cell, potassium levels decrease

• Monitor potassium levels

• Serum calcium levels may be low with chronic metabolic acidosis

– Must be corrected before treating acidosis

Respiratory Acidosis

pH

 Less than 7.35

PaCO₂

Greater than 45 mm Hg

HCO₃–

Causes

• Always due to respiratory problem with inadequate excretion of CO₂

• Airway obstruction, pneumonia, asthma, chest injuries, or pulmonary edema

• Chronic obstructive pulmonary disease such as emphysema

• With opiate use that depresses the respiratory rate

Signs and Symptoms

• History of respiratory obstruction (acute or chronic)

• Dyspnea

• Weakness

Management

• Establishment or maintenance of an airway

– Tracheostomy

– Endotracheal tube

• Oxygen administration

• Mechanical ventilator

Conservative Treatment

• Postural drainage, deep-breathing exercises, bronchodilators, and antibiotics if indicated

Metabolic Alkalosis

pH

Greater than 7.45

PaCO₂

Normal 35–45 mm Hg

HCO₃–

Greater than 26 mEq/L

Causes

• Vomiting

• Extensive gastrointestinal suction

• Hypokalemia

• Excessive consumption of antacids with bicarbonate

Signs and Symptoms

• Neurologic signs:

– Irritability, disorientation, lethargy, muscle twitching, tingling and numbness of the fingers, convulsions

• Respiratory manifestations:

– Slow, shallow respirations, decreased chest movements, cyanosis

• There may be symptoms of potassium and calcium depletion

Signs and Symptoms (cont.)

• If the alkalosis progresses, tetany, seizures, and coma

• Tetany is characterized by severe muscle cramps,

Treatment

• Correct underlying cause

• Restore the body fluids to a less alkaline state

• Fluids and electrolytes replacement orally and parenterally as needed

• Emergency measures include the administration of an acidifying solution, such as ammonium chloride

Respiratory Alkalosis

pH

> 7.45

PaCO₂

< than 35 mm Hg

HCO₃–

Causes

• Always due to hyperventilation

• Hyperventilation (a rapid respiratory rate) results in respiratory alkalosis

– It is usually caused by anxiety, high fever, and overdose of aspirin – Hyperventilation can be caused by hypoxemia, reactions to certain

drugs, pain, and panic

• Overzealous use of mechanical ventilation also can cause hyperventilation

• Head injuries may also lead to hyperventilation

Signs and Symptoms

• Deep, rapid breathing

• Tingling of the fingers

• Pallor around the mouth

• Dizziness

• Spasms of the muscles of the hands

Treatment

• Address the underlying disorder

• Prevent further hyperventilation and help the patient re-establish a normal level of carbon dioxide in the blood

• Sedatives may be given to calm the patient

Treatment (cont.)

• To aid in the retention of carbon dioxide, the patient may be instructed to hold the breath, or to breathe into a paper sack and re-breathe the carbon dioxide just exhaled

Acid-Base Imbalances

Home Care Considerations

• Sodium restriction

• Manage underlying cause

• Monitor tests

Intravenous Fluid Therapy

• Maintenance fluids

• Oral and parenteral replacement

• Parenteral nutrition

• Blood and blood products

Nursing Responsibilities

Administering IV Fluids

• The goals of nursing care for a patient receiving an IV infusion are to

– Prevent infection

– Minimize physical injury to the veins and surrounding tissues

– Administer the correct fluid at the prescribed time and at a safe rate of flow

– Observe the patient’s reaction to the fluid and medications being administered

Rights of IV Therapy

• Right solution with or without additives as ordered; the correct solution to follow what has been infusing

• Right dose (amount) of solution and additive as ordered

Regulating the Rate of Flow

• Monitor infusions

• Principles affecting flow rates

Elder Care Points

• Frequent IV infusion monitoring

IV Therapy

• Intake

• Flushing peripheral and central lines

• Facility policy and procedures

• Subcutaneous infusion

• Hypodermoclysis

• Epidural infusion

• Parenteral nutrition: TPN and PPN

• Patient-controlled analgesia

Applicable Nursing Diagnoses

• Deficient fluid volume

• Excess fluid volume

• Risk for imbalanced fluid volume

• Ineffective tissue perfusion

• Decreased cardiac output

• Impaired gas exchange

• Ineffective breathing pattern

Planning

• Patient will exhibit normal skin turgor

• Patient’s weight will stabilize at normal baseline

• Intake and output will be balanced

• Blood gases will return to normal

• Breath sounds will be clear to auscultation

• There will be no evidence of edema

• Electrolyte values will be within normal limits

Implementation

• Fluid and electrolytes

• Diuretics

• Daily weights

• Skin care

Evaluation

– Perform evaluations to see if nursing

interventions are assisting the patient to meet expected outcomes

– If the patient is not progressing toward

achievement of the outcomes, problem-solve and think critically to determine why, then

alter the plan of care appropriately

– When a specific outcome is met, discontinue that portion of the plan

Community Care

• Frequent monitoring

• Medication safety

• Patient teaching

IV Site Selection

Figure 13-7

Complications of IV Therapy

• Fluid overload

• Air embolism

• Septicemia, other infections

• Infiltration, extravasation

• Phlebitis

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