2 questions
You answered 2 out of 2 questions correctly on the first attempt.
1. 1.
Which two systems in the body are most responsible for regulating the pH in extracellular
fluids?
You correctly answered:
Respiratory and renal systems
.
Respiratory and renal systems
Correct!
When the serum pH changes, buffers are used to regulate and maintain an acid–base
balance. The respiratory system controls levels of serum carbon dioxide, and the renal
system controls levels of serum bicarbonate.
Cardiovascular and renal systems
Neuromuscular and respiratory systems
Cardiovascular and neuromuscular systems
2. 2.
Primary acid–base disorders are classified as metabolic or respiratory depending on
which factor?
You correctly answered:
The primary cause of the change in serum pH
.
The level of absorbed oxygen in the blood
The primary cause of the change in serum pH
Correct!
Respiratory disorders result from changes in the serum carbon dioxide level, and
metabolic disorders result from changes in the serum bicarbonate level. The two primary
respiratory disorders, respiratory acidosis and respiratory alkalosis, have an increased or
decreased carbon dioxide serum level and a normal bicarbonate serum level. The two
primary metabolic disorders, metabolic acidosis and metabolic alkalosis, have a normal
carbon dioxide serum level and an increased or decreased bicarbonate serum level.
The concentration of buffers in the body
The measured quantity of intracellular fluids
Table 1–1 Common Causes of Primary Acid–
Base Imbalances
Imbalance
Common Causes
↑ Acid production
Metabolic acidosis





pH < 7.35
HCO3 < 24
mEq/L
Critical values
pH < 7.20
HCO3 < 10
mEq/L



Lactic acidosis
Ketoacidosis related to diabetes, starvation, or alcoholism
Salicylate toxicity
↓ Acid excretion

Renal failure
↑ Bicarbonate loss

Diarrhea, ileostomy drainage, intestinal fistula
Imbalance

Common Causes
Biliary or pancreatic fistulas
↑ Chloride



Metabolic alkalosis





pH > 7.45
HCO3 > 28
mEq/L
Critical values
pH > 7.60
HCO3 > 40
mEq/L
Sodium chloride intravenous (IV) solutions
Renal tubular acidosis
Carbonic anhydrase inhibitors
↑ Acid loss or excretion


Vomiting, gastric suction
Hypokalemia
↑ Bicarbonate


Alkali ingestion (bicarbonate of soda)
Excess bicarbonate administration
Acute respiratory acidosis
Respiratory acidosis





pH < 7.35
PaCO2 > 45
mmHg
Critical values
pH < 7.20
PaCO2 > 77
mmHg




Acute respiratory conditions (pulmonary edema, pneumonia,
acute asthma)
Opiate overdose
Foreign body aspiration
Chest trauma
Chronic respiratory acidosis



Chronic respiratory conditions (COPD, cystic fibrosis)
Multiple sclerosis, other neuromuscular diseases
Stroke




Anxiety-induced hyperventilation
Fever
Early salicylate intoxication
Hyperventilation with mechanical ventilator
Respiratory alkalosis





pH > 7.45
PaCO2 < 35
mmHg
Critical values
pH > 7.60
PaCO2 < 20
mmHg
Table 1–2 Compensation for Simple Acid–
Base Imbalances
Primary
Disorder
Cause
Compensation
Effect on
ABGs
↓ pH
Metabolic
acidosis
Excess nonvolatile acids;
bicarbonate deficiency
Rate and depth of respirations increase,
eliminating additional CO2.
↓ HCO3
↓ PaCO2
↑ pH
Metabolic
alkalosis
Bicarbonate excess
Rate and depth of respirations decrease; CO2 is
↑ HCO3
retained.
↑ PaCO2
↓ pH
Respiratory
acidosis
Retained CO2 and excess
carbonic acid
Kidneys conserve bicarbonate to restore
carbonic acid: bicarbonate ratio of 1:20.
↑ PaCO2
↑ HCO3
↑ pH
Respiratory
alkalosis
Loss of CO2 and deficient
carbonic acid
Kidneys excrete bicarbonate and conserve H+
to restore carbonic acid: bicarbonate ratio.
↓ PaCO2
↓ HCO3
2 questions
You answered 2 out of 2 questions correctly on the first attempt.
1. 1.
Which buffer system is most associated with the lungs in regulating acid–base balance?
You correctly answered:
The carbonic acid bicarbonate buffer system
.
The phosphate hemoglobin binding buffer system
The carbonic acid bicarbonate buffer system
Correct!
The carbonic acid bicarbonate buffer system becomes active when cellular reactions
produce the waste product, carbon dioxide, which enters the bloodstream and combines
with water to become carbonic acid. The carbonic acid dissociates to bicarbonate ions
and hydrogen ions. The bicarbonate helps to neutralize other acids in the body while
traveling to the lungs. In the lungs, it converts back to water and carbon dioxide and is
released as a waste product.
The protein intracellular synthesis buffer system
The intracellular chemical buffer system
2. 2.
In metabolic acidosis, the buffer system in the kidneys raises the pH value to correct an
acid–base imbalance with which actions?
You correctly answered:
Increasing bicarbonate retention and increasing acid excretion
.
Increasing bicarbonate retention and increasing acid excretion
Correct!
To correct metabolic acidosis, the buffer system in the kidneys is stimulated to increase
bicarbonate retention and increase acid excretion. This acts to decrease serum carbonic
acid concentration and raise the pH value to correct an acid–base imbalance. If the
kidneys are overwhelmed and cannot correct the imbalance, further compensation is
needed and the respiratory system will increase breathing to expel carbon dioxide in the
lungs.
Decreasing bicarbonate retention and decreasing acid excretion
Slowing breathing down to increase retention of carbon dioxide
Increasing breathing to decrease loss of carbon dioxide
Metabolic Acidosis
ETIOLOGY
Conditions that increase
nonvolatile acids in the blood (e.g.,
renal impairment, diabetes
mellitus, starvation)
Conditions that decrease
bicarbonate (e.g., prolonged
diarrhea, excessive use of
laxatives)
Excessive infusion of chloridecontaining IV fluids (e.g., NaCl)
Excessive ingestion of acids (e.g.,
salicylates)
Cardiac arrest
CLINICAL
MANIFESTATIONS
 Diminished appetite
 Nausea and vomiting
 Abdominal pain
 Weakness
 Fatigue
 Headache
 General malaise
 Decreasing LOC
 Dysrhythmia
 Bradycardia
 Warm, flushed skin
 Skeletal problems
 Hyperventilation
(Kussmaul
respirations)
 Dyspnea
CLINICAL THERAPIES





Monitor ABG values,
intake and output,
and LOC.
Position patient to
facilitate chest
expansion.
Provide oral care for
dry mouth.
Administer IV
sodium bicarbonate
carefully if ordered.
Treat underlying
problem as ordered.
Clinical Manifestations and Therapies
Metabolic Alkalosis
CLINICAL
MANIFESTATIONS
ETIOLOGY
CLINICAL THERAPIES
Excessive acid losses due to
vomiting or gastric suction

Excessive use of potassium-losing
diuretics
Excessive adrenal corticoid
hormones due to:




Cushing syndrome
Hyperaldosteronism
Excessive bicarbonate
intake from antacids
Parenteral sodium
bicarbonate infusion








Confusion
Decreasing LOC
Hyperreflexia
Tetany
Dysrhythmias
Hypotension
Seizures
Respiratory failure




Monitor intake and
output closely.
Monitor vital signs,
especially respirations
and LOC.
Administer ordered IV
fluids carefully.
Administer oxygen as
ordered.
Treat underlying
problem.
Clinical Manifestations and Therapies
Respiratory Acidosis
ETIOLOGY
Diseases of the
airways, such as
asthma, chronic
obstructive lung
disease
Disease of the chest
CLINICAL
MANIFESTATIONS
Acute respiratory
acidosis:
CLINICAL THERAPIES






Headache
Warm, flushed
skin
Elevated pulse
Blurred vision


Assist with identification/treatment of
underlying cause.
Observe for altered respiratory
excursion, rate, and depth. Auscultate
breath sounds.
Assess LOC and progressive changes.
Place in semi-Fowler position or Fowler
position as tolerated.
ETIOLOGY
Drugs that suppress
breathing, such as
opioids, or alcohol
Obstructive sleep
apnea
CLINICAL
MANIFESTATIONS
 Irritability or
altered mental
status
 Decreasing LOC
 Cardiac
dysrhythmias
 Cardiac arrest
Chronic respiratory
acidosis:





Weakness
Dull headache
Sleep
disturbances with
daytime
sleepiness
Impaired memory
Personality
changes
CLINICAL THERAPIES




Encourage the patient with chronic
respiratory acidosis to use pursed-lip
breathing.
Administer oxygen as indicated by
mask, cannula, or mechanical
ventilation. Increase or decrease
respiratory rate on ventilator. Modify
respiratory settings as needed.
Administer medications as indicated; for
example, naloxone hydrochloride
(Narcan).
Use continuous positive airway pressure
(CPAP).
Respiratory Alkalosis
ETIOLOGY
Hyperventilation due to:







Brainstem injury
Elevated body
temperature or fever
Extreme anxiety
Hypoxia
Increased basal
metabolic rate
Overventilation with
a mechanical
ventilator
Salicylate overdose
CLINICAL
MANIFESTATIONS









Dizziness
Numbness and tingling
around mouth, hands,
and feet
Palpitations
Dyspnea
Chest tightness
Anxiety/panic
Tremors
Tetany
Seizures or loss of
consciousness
CLINICAL THERAPIES






Monitor vital signs, LOC,
and ABGs.
Encourage patient to
breathe more slowly; teach
breathing and stress
reduction techniques.
Administer sedative or
antianxiety agent as
ordered.
Monitor ventilator settings.
Administer oxygen as
ordered.
Maintain fluid status.