ACID-BASE BALANCE

OVERVIEW

INTRODUCTION• An important property of blood is its degree of

acidity or alkalinity • The body's balance between acidity and

alkalinity is referred to as acid-base balance• The acidity or alkalinity of any solution,

including blood, is indicated on the pH scale.

INTRODUCTION• Acidosis and alkalosis are not diseases but

rather are the result of a wide variety of disorders. The presence of acidosis or alkalosis provides an important clue to doctors that a serious problem exists.

INTRODUCTION• Acidosis and alkalosis are categorized as

metabolic or respiratory, depending on their primary cause.

METABOLIC• caused by an imbalance in the production of

acids or bases and their excretion by the kidneys.

• the kidneys are the problem and can only be fixed by the lungs

RESPIRATORY• caused primarily by changes in carbon dioxide

exhalation due to lung or breathing disorders.• REMEMBER: CO2 = mild acidic• the lungs are the problem and can only be

fixed by the kidneys.

What is Blood pH? Acidity and alkalinity are expressed on the pH

scale, which ranges from 0 (strongly acidic) to 14 (strongly basic, or alkaline). A pH of 7.0, in the middle of this scale, is neutral. Blood is normally slightly basic, with a pH range of 7.35 to 7.45. To function properly, the body maintains the pH of blood close to 7.40.

Arterial Blood Gas• measures the levels of oxygen and carbon dioxide in

the blood to find out how well the lungs are working.

• uses blood drawn from an artery, where the oxygen and carbon dioxide levels can be measured before they enter body tissues and become changed.

Arterial Blood Gas• An ABG test measures for values of oxygen, carbon dioxide, and/or pH

that are not normal, which can be caused by changes in:

1. Lung function.2. Heart function and blood flow.3. Kidney function.4. How well the body uses food for energy (metabolism).5. The use of some medicines.

Arterial Blood Gas: Procedure• Usually, blood is taken from an artery. The blood may be collected from the radial artery in

the wrist, the femoral artery in the groin, or the brachial artery in the arm.• The HCP may test circulation to the hand before taking a sample of blood from the wrist area.

Allen’s Test• The HCP will insert a small needle through the skin into the artery. Patient can choose to have

numbing medicine (anesthesia) applied to the site before the test begins.• In some cases, blood from a vein may be used.• After the blood is taken, pressure is applied to the site for a 5-10 minutes to stop the

bleeding. The health care provider will watch the site for signs of bleeding or circulation problems.

• The sample must be quickly sent to a laboratory for analysis to ensure accurate results.

Arterial Blood Gas: Normal Values• Partial pressure of oxygen (PaO2) - 75 - 100 mmHg

• Partial pressure of carbon dioxide (PaCO2) - 38 - 42 mmHg

• Arterial blood pH of 7.38 - 7.42

• Oxygen saturation (SaO2) - 94 - 100%

• Bicarbonate - (HCO3) - 22 - 28 mEq/L

Arterial Blood Gas: Considerations1. Assess if the patient is taking any blood-thinning medications

(anticoagulants), including aspirin.

2. Notify MD if you notice bleeding, bruising, numbness, tingling, or change in skin color at the puncture site.

ACID-BASE BALANCE

IMBALACES

ACIDOSISAcidosis is excessive blood acidity caused by:

• an overabundance of acid in the blood • or a loss of bicarbonate from the blood

(metabolic acidosis),• or by a buildup of carbon dioxide in the blood

that results from poor lung function or slow breathing (respiratory acidosis).

METABOLIC ACIDOSIS• Develops when high amount of acid was ingested.

Such as: Methanol, Antifreeze, large dose of aspirin.• can also occur as a result of abnormal metabolism.

• The body produces excess acid in the advanced stages of shock and in poorly controlled type 1 diabetes mellitus.

Symptoms: • Nausea, Vomiting, and Fatigue• May breath faster and deeper than normal.

METABOLIC ACIDOSIS

Treatment:• Depends on the primary cause.

RESPIRATORY ACIDOSIS• develops when the lungs do not expel carbon dioxide

adequately, a problem that can occur in diseases that severely affect the lungs (such as emphysema, chronic bronchitis, severe pneumonia, pulmonary edema, and asthma).

• can also develop when diseases of the brain or of the nerves or muscles of the chest impair breathing.

• people can develop respiratory acidosis when their breathing is slowed due to oversedation from opioids (narcotics) or strong drugs that induce sleep (sedatives).

RESPIRATORY ACIDOSISSymptoms:• Headeache and Drowziness

Intervention:• Improve fxn of the lungs• Check for airway patency.• Improve Oxigenation.• Provide medications as prescribed.

ALKALOSIS• caused by an overabundance of bicarbonate

in the blood • loss of acid from the blood (metabolic

alkalosis), • low level of carbon dioxide in the blood that

results from rapid or deep breathing (respiratory alkalosis).

METABOLIC ALKALOSIS• Lost of great amount of acid and gain

amount of bicarbonate in the blood.• In addition, metabolic alkalosis can develop

when excessive loss of sodium or potassium affects the kidneys' ability to control the blood's acid-base balance.

• For instance, loss of potassium sufficient to cause metabolic alkalosis may result from an overactive adrenal gland or the use of diuretics.

METABOLIC ALKALOSIS• Clinical Manifestations

– Hypoventilation– Dysrhythmias– Hypokalemia and hypocalcemia– PaCO2 normal or slightly increased.

METABOLIC ALKALOSIS• Intervention:

– Replace water and electrolytes (Na and K) while treating the cause.

– Occasionally, when metabolic alkalosis is very severe, dilute acid is given intravenously.

– Monitor Respiratory and Cardiac status.– Monitor for s/sx of hypokalemia and hypocalcemia.– Assess neuro status and ADL– Plan scheduled rest periods.

RESPIRATORY ALKALOSIS• develops when rapid, deep breathing

(hyperventilation) causes too much carbon dioxide to be expelled from the bloodstream.

• COMMON CAUSES:– Anxiety– Hypoxemia– Fever– Aspirin Overdose

RESPIRATORY ALKALOSIS• Clinical Manifestations:

– Tachypnea– Syncope, Convulsions to coma.– Weakness, paresthesia, tetany– Hypokalemia and Hypocalcemia

• Nursing Interventions:– Monitor V/S– Implement CO2 retention measures– Assess s/sx of hypocalcemia and hypokalemia– Implement prevention of pain, anxiety, fever if present.

ACID-BASE BALANCEAdditional

Informations

Additional Information ROME – Respiratory Opposite, Metabolic Equal– Respiratory Opposite

• pH elevated PCO2 diminished = alkalosis (respiratory)• pH diminished PCO2 elevated = acidosis (respiratory)

– Metabolic Equal• pH elevated HCO3 elevated = alkalosis (metabolic)• pH diminished HCO3 diminished = acidosis (metabolic)

Key Concepts:• Electrolytes found inside the cells are small numbers (like K+ 3.5-

5.0 vs Na+ 135-145)

• Since potassium is normally found inside the cell, anytime you have tissue damage (cellular contents spill out) then serum K+ (potassium levels in the blood) will rise

• Mg and K+ can only be excreted by the kidneys so if urine output is decreased you have to monitor these levels closely and decrease any dietary intake (including antacids, etc.) they contain them.

Key Concepts:• Na+ levels are a good indicator of hydration. A high Na+ means

dehydration, or fluid volume deficit, and a low sodium means fluid overload, or fluid volume excess.

• Mg and Phos are inversely proportional. If one goes up, the other goes down. Therefore hypermagnesiemia is the same as hypophosphatemia.

• The kidneys can excrete HCO3(base) or H+(acid) to correct respiratory problems but this usually takes at least three days to become effective.

Key Concepts:• The lungs only have one compound to fix an acid base imbalance

and that is CO2, which is an acid, and it will either be excreted (hyperventilation) to correct metabolic acidosis or retained (hypoventilation) to fix metabolic alkalosis. The effects are immediate.

• The result of the 'problem being fixed' by the lungs/kidneys is only the body's attempt to restore a normal pH. It doesn't actually mean the problem is fixed, just the pH. That's where you get compensated acid base problems. You still have an abnormal ABG with an acid-base imbalance, however, you have a normal pH because the body has compensated.

ACID-BASE BALANCEPost Test

Question 1• Which individual would least likely suffer from a disturbance

in fluid volume, electrolyte, or acid-base balance?

A. An infant suffering from gastroenteritis for three days B. An elderly client suffering from a type I decubitus C. Adults with impaired cardiac function D. Clients who are confused.

Question 2• An elderly patient was hydrated with lactated Ringer's solution in the

emergency room for the last hour. During the most recent evaluation of the patient by the nurse, a finding of a rapid bounding pulse and shortness of breath were noted. Reporting this episode to the physician, the nurse suspects that the patient now shows signs of: A. Hypovolemia, and needs more fluids

B. Hypervolemia, and needs the fluids adjusted C. An acid-base disturbance D. Needing no adjustment in fluid administration

Question 3• A client taking lasix (furosemide) for congestive heart failure is seeing the

physician for a potassium value of 3.0. An order for oral potassium taken daily is written and discussed with the client. In addition, potassium-rich foods should be eaten. The nurse educator meets with this client and has the client identify all of the following foods as potassium-rich except:

A. Baked potato B. White bread C. Apricot D. Orange juice

Question 4• Edema that forms in clients with kidney disease is due to:

A. Reduced plasma oncotic pressure, so that fluid is not drawn into the capillaries from interstitial tissues

B. Decreased capillary hydrostatic pressures pushing fluid into the interstitial tissues

C. Capillaries becoming less permeable, allowing fluid to escape into interstitial tissues

D. Obstructed lymph flow that assists the movement of fluid from the interstitial tissues back into the vascular compartment

Question 5• A client suffering from a narcotic overdose is seen in the Emergency

Department. The client is confused, with warm, flushed skin, headache, and weakness. Vital signs of noted are T 102.6, HR 128, R 24, and BP 130/86. A blood gas analysis sample was drawn on room air, and the results are as follows: pH 7.33, PaCO2 53, PaO2 72, HCO3 24. This client is at risk for: A. Respiratory acidosis

B. Respiratory alkalosis C. Metabolic acidosis D. Metabolic alkalosis

Question 6• Measurements related to fluid balance of clients that a nurse can initiate

without a physician's order include:

A. Daily weights, vital signs, and fluid intake and output B. Daily weights, diuretics, and waist measurement C. Monitoring temperature, fluid intake and output, and calorie count D. Auscultating lung sounds, monitoring color of urine, and placing a Foley

catheter into the client

Question 7• The nurse has been invited to discuss "the importance of promoting a good fluid and

electrolyte balance in children" for a group of parents at the local school parents club meeting. Of the following actions, which is not representative of this topic?

A. Recognizing possible risk factors for fluid and electrolyte balance, such as prolonged or repeated vomiting, frequent watery stools, or inability to consume fluids

B. Increasing fluid intake before, during, and after strenuous exercise, particularly when the environmental temperature is high, and replacing lost electrolytes from excessive perspiration as needed with commercial electrolyte solutions

C. Consuming six to eight glasses of water daily D. Encouraging excessive amounts of foods or fluids high in salt or caffeine

Question 8• The nurse is admitting a new client, 80 years old, with congestive heart failure into your

home health agency. The following assessment findings have been determined after meeting the client: overweight but no gain since the client left the hospital two days ago; VS: T 99.0, HR 100, R 22, BP 130/86. Foods eaten include canned soup at each meal, ham, and cheese. When completing the care plan for this client, the nurse should include which of the following nursing diagnosis:

A. Improved Gas Exchange B. Risk for Fluid Volume Deficit C. Risk for Fluid Volume Imbalance D.Impaired Skin Integrity

Question 9• The results of an arterial blood gas are as follows: pH:

7.5, PaCO2: 50, PaO2: 88, HCO3: 28; Base excess: +5. Evaluate the acid-base imbalance.

=____________?

Question 10• Following surgery, the client requires a blood transfusion.

The main reason the nurse wants to complete the unit transfusion within a four-hour period that blood:

A. Hanging for a longer four hours creates an increased risk of sepsis

B. May clot in the bag C. May evaporate D. May not clot in the recipient after this time period

ACID-BASE BALANCEAnswers

Question 1• Which individual would least likely suffer from a disturbance

in fluid volume, electrolyte, or acid-base balance?

A. An infant suffering from gastroenteritis for three days B. An elderly client suffering from a type I decubitus C. Adults with impaired cardiac function D. Clients who are confused.

Question 1• Correct Answer: An elderly client suffering from a type I decubitus • Objective: Identify factors affecting normal body fluid, electrolyte, and acid-base balance.

Rationale: The proportion of body water decreases with aging. Tissue trauma, such as burns, causes fluids and electrolytes to be lost from the damaged cells, and the breakdown in the continuity of the tissue. In Type I Decubitus, the skin remains intact, and any shifting of fluids is due to the inflammatory process and internally maintained within the body. Vomiting and diarrhea can cause significant fluid loses. Age, sex, and body fat affect total body water. Infants have the delete spaces highest proportion of water; it accounts for 70-80% of their body weight. Decreased blood flow to the kidneys as caused by impaired cardiac function stimulates the renin-angiotensin-aldosterone system, causing sodium and water retention. Clients who are confused or unable to communicate are at risk for inadequate fluid intake. Age does not play a significant factor here.

Question 2• An elderly patient was hydrated with lactated Ringer's solution in the

emergency room for the last hour. During the most recent evaluation of the patient by the nurse, a finding of a rapid bounding pulse and shortness of breath were noted. Reporting this episode to the physician, the nurse suspects that the patient now shows signs of: A. Hypovolemia, and needs more fluids

B. Hypervolemia, and needs the fluids adjusted C. An acid-base disturbance D. Needing no adjustment in fluid administration

Question 2• Correct Answer: Hypervolemia, and needs the fluids adjusted • Objective: Evaluate the effect of nursing and collaborative interventions

on the client's fluid, electrolyte, or acid-base balance.

Rationale: Isotonic solutions has the same osmolality as body fluids. Isotonic solutions, such as Normal Saline and Ringer's Lactate, initially remain in the vascular compartment, expanding vascular volume. Isotonic imbalances occur when water and electrolytes are lost or gained in equal proportions, and serum osmolality remains constant.

Question 3• A client taking lasix (furosemide) for congestive heart failure is seeing the

physician for a potassium value of 3.0. An order for oral potassium taken daily is written and discussed with the client. In addition, potassium-rich foods should be eaten. The nurse educator meets with this client and has the client identify all of the following foods as potassium-rich except:

A. Baked potato B. White bread C. Apricot D. Orange juice

Question 3• Correct Answer: White bread • Objective: Teach clients measures to maintain fluid and

electrolyte balance.

Rationale: White bread is known to help meet fiber needs for the body. Potassium is found in many fruits, vegetables, meat, and fish.

Question 4• Edema that forms in clients with kidney disease is due to:

A. Reduced plasma oncotic pressure, so that fluid is not drawn into the capillaries from interstitial tissues

B. Decreased capillary hydrostatic pressures pushing fluid into the interstitial tissues

C. Capillaries becoming less permeable, allowing fluid to escape into interstitial tissues

D. Obstructed lymph flow that assists the movement of fluid from the interstitial tissues back into the vascular compartment

Question 4• Your Answer: Reduced plasma oncotic pressure, so that fluid is not drawn into the

capillaries from interstitial tissues • Objective: Discuss the risk factors for and the causes and effects of fluid,

electrolyte, and acid-base imbalances.

Rationale: The edema is due to low levels of plasma proteins that exist with this disease, altering the oncotic pressure that helps regulate fluid movement in the vascular space moving into interstitial area. Increased capillary hydrostatic pressure is the cause. Capillaries have increased permeability when edema formation is possible. Obstructed lymph flow impairs the movement of fluid from interstitial tissues back into the vascular compartment, resulting in edema.

Question 5• A client suffering from a narcotic overdose is seen in the Emergency

Department. The client is confused, with warm, flushed skin, headache, and weakness. Vital signs of noted are T 102.6, HR 128, R 24, and BP 130/86. A blood gas analysis sample was drawn on room air, and the results are as follows: pH 7.33, PaCO2 53, PaO2 72, HCO3 24. This client is at risk for: A. Respiratory acidosis

B. Respiratory alkalosis C. Metabolic acidosis D. Metabolic alkalosis

Question 5• Answer: Respiratory acidosis • Objective: Identify examples of nursing diagnoses, outcomes,

and interventions for clients with altered fluid, electrolyte, or acid-base balance.

Rationale: Narcotic overdose causes more carbonic acid levels to rise because of hypoventilation and carbon dioxode retention.

Question 6• Measurements related to fluid balance of clients that a nurse can initiate

without a physician's order include:

A. Daily weights, vital signs, and fluid intake and output B. Daily weights, diuretics, and waist measurement C. Monitoring temperature, fluid intake and output, and calorie count D. Auscultating lung sounds, monitoring color of urine, and placing a Foley

catheter into the client

Question 6• Correct Answer: Daily weights, vital signs, and fluid intake and output • Objective: Teach clients measures to maintain fluid and electrolyte

balance.

Rationale: Daily weights, checking vital signs, and monitoring fluid I&O all fall within the realm of nursing interventions. The remaining interventions either have the nurse perform a task requiring an MD order, such as giving diuretics or placing a Foley catheter, or have an action unrelated to this problem, such as the calorie count.

Question 7• The nurse has been invited to discuss "the importance of promoting a good fluid and

electrolyte balance in children" for a group of parents at the local school parents club meeting. Of the following actions, which is not representative of this topic?

A. Recognizing possible risk factors for fluid and electrolyte balance, such as prolonged or repeated vomiting, frequent watery stools, or inability to consume fluids

B. Increasing fluid intake before, during, and after strenuous exercise, particularly when the environmental temperature is high, and replacing lost electrolytes from excessive perspiration as needed with commercial electrolyte solutions

C. Consuming six to eight glasses of water daily D. Encouraging excessive amounts of foods or fluids high in salt or caffeine

Question 7• Answer: Encouraging excessive amounts of foods or fluids high in salt or

caffeine • Objective: Teach clients measures to maintain fluid and electrolyte

balance.

Rationale: Salt causes the body to retain fluids due to an increase in the concentration of sodium and the release of ADH. Caffeine acts as a diuretic in individuals and may lead to loss of excess fluids in the body. The remaining identified measures are all appropriate.

Question 8• The nurse is admitting a new client, 80 years old, with congestive heart failure into your

home health agency. The following assessment findings have been determined after meeting the client: overweight but no gain since the client left the hospital two days ago; VS: T 99.0, HR 100, R 22, BP 130/86. Foods eaten include canned soup at each meal, ham, and cheese. When completing the care plan for this client, the nurse should include which of the following nursing diagnosis:

A. Improved Gas Exchange B. Risk for Fluid Volume Deficit C. Risk for Fluid Volume Imbalance D.Impaired Skin Integrity

Question 8• Answer: Risk for Fluid Volume Imbalance • Objective: Identify examples of nursing diagnoses, outcomes, and

interventions for clients with altered fluid, electrolyte, or acid-base balance.

Rationale: Sodium is found in high quantities in the foods noted that the client has consumed. When sodium levels increase in the body, water is retained, adding to the volume of fluid in circulation, making it harder for the body to move fluids through the circulation. Therefore, the excess fluid may in time impair gas exchange if levels eventually act on the lungs; fluid volume is increasing, not decreasing, in this situation, and this problem has no involvement with platelets.

Question 9• The results of an arterial blood gas are as follows: pH:

7.5, PaCO2: 50, PaO2: 88, HCO3: 28; Base excess: +5. Evaluate the acid-base imbalance.

=____________?

Question 9• Correct Answer: Metabolic alkalosis with a respiratory compensation. • Objective: Collect assessment data related to the client’s fluid,

electrolyte, and acid-base balances.

Rationale: Arterial blood gases are performed to evaluate the client’s acid-base balance and oxygenation. pH is the measure of relative acidity or alkalinity. PaCO2: is the partial pressure of carbon dioxide in arterial plasma. PaO2 is the pressure exerted by oxygen dissolved in the plasma, HCO3: is the measure of the metabolic component of acid-base balance. Base excess is a calculated value of bicarbonate levels.

Question 10• Following surgery, the client requires a blood transfusion.

The main reason the nurse wants to complete the unit transfusion within a four-hour period that blood:

A. Hanging for a longer four hours creates an increased risk of sepsis

B. May clot in the bag C. May evaporate D. May not clot in the recipient after this time period

Question 10• Answer: Hanging for a longer four hours creates an increased risk of

sepsis. • Objective: Implement measures to correct imbalances of fluids and

electrolytes or acids and bases such as enteral or parenteral replacements and blood transfusions.

Rationale: Hanging for a longer four hours creates an increased risk of sepsis, which is why the nurse wants to complete the unit transfusion in less than four hours. The remaining items are not likely to happen.

ACID-BASE BALANCEEND