Arterial Blood Gases Flashcards
Normal human pH is _____
7.35 - 7.45
Think of CO2 as the Respiratory _____
Acid
T/F H+ ions are a normal product of normal cellular metabolism.
T
There are several buffering systems utilized in the body to
manage the pH, the main one being the _____
Carbonic Acid- Bicarbonate System
Think of HCO3- as the Metabolic ____
Base
The ____ are the Metabolic System that controls the HCO3- level
kidneys
The respiratory system manages
the pH by _____
increasing or
decreasing the respiratory rate
and inspiration depth.
The kidneys manage the pH by _____
retaining HCO3 or by eliminating H+ in urine.
Metabolic Acidosis
○ Results from decreased HCO3- or increased Acid retention.
■ Causes an increased H+ concentration, decreasing the pH
Clinical causes of metabolic acidity:
■ Failure of the kidneys to successfully excrete extracellular acids
(due to renal diseases, whether acute or chronic).
■ Formation of excess metabolic acids in the body (such as diabetic
ketoacidosis, lactic acidosis, etc.).
■ Loss of base from body fluids (such as severe diarrhea, which
results in loss of large amounts of bicarbonate in the feces)
Treatment of metabolic acidosis
centers on treating the underlying condition.
■ In more severe cases, treatment with alkali therapy (ie. NaHCO3)
may be indicated to raise and maintain pH to > 7.2
Metabolic Alkalosis
○ Results from increased HCO3- concentration or loss of excess H+.
■ Causes a decreased H+ concentration, increasing the pH
Clinical causes of metabolic alkalosis:
■ Increased ingestion of alkaline drugs, such as Tums (NaHCO3).
■ Thiazide and Loop Diuretics medications.
■ Excessive vomiting can result in loss of large amounts of acid from
the gastric hydrochloric acid (HCl).
■ Excessive Aldosterone secretion results in increased renal Na+
reabsorption, which also causes increased urinary excretion of H+
Treatment of metabolic aklalosis
focuses on the treating/correcting the underlying condition.
■ May also involve correcting electrolyte imbalances that are present.
Respiratory Acidosis:
○ Results from decreased ventilation and increased PCO2.
■ Causes increased H2CO3 and H+, resulting in decreased pH
Clinical causes of Hypoventilation (Respiratory acidosis)
■ Damage to respiratory center in the medulla oblongata.
■ Obstructive lung conditions, such as COPD, chest trauma, etc
■ Factors that interfere with pulmonary gas exchange, such as
pneumonia, pulmonary embolism, cardiac arrest, etc
■ Other causes of hypoventilation, such as narcotic overdose
Treatment of respiratory acidosis:
Treat underlying condition and consider hyperventilation.
■ Often requires admission to the ICU; hyperventilation is often done
with BIPAPs or endotracheal intubation.
Respiratory Alkalosis:
○ Results from increased ventilation and decreased PCO2.
■ Causes decreased H2CO3 and H+, resulting in increased pH
Clinical causes of Hyperventilation (respiratory alkalosis)
■ Situations such as anxiety, panic attacks, fever,
some head injuries, COPD, asthma, pneumonia,
pulmonary fibrosis, etc.
■ Can be iatrogenic hyperventilation
Treatment of respiratory alkalosis
Focused the underlying condition.
■ Respiratory alkalosis itself is rarely life
threatening and emergent treatment is usually not indicated
Arterial Blood Gases
An Arterial Blood Gas, or ABG, is a diagnostic assessment
that can be used to evaluate a patient’s Acid-Base status, and diagnose Hypoxia
ABGs can diagnose _____
hypoxia
ABG process
● The procedure involves a needle being placed in a peripheral
artery to obtain a sample of arterial blood.
● An ABG provides the clinician with…
○ Arterial pH
○ Arterial PCO2
○ Arterial PO2
○ Percentage of O2 Saturation
○ Bicarbonate (HCO3-)
Patients who typically require an arterial blood gas measurement are those who are
○ In respiratory failure.
○ Critically ill or rapidly deteriorating.
■ Examples: Sepsis, multi organ failure, DIC, etc.
○ In a state of uncontrolled DM (and concern for DKA).
○ Suspected of taking an overdose of dangerous toxin
