Module 05: ABG Interpretation (Active Recall) Flashcards
This is used to identify the specific acid-base disturbance and degree of compensation. This should be analyzed with electrolyte imbalance
Arterial blood gas (ABG) values
What should the nurse perform on the first time blood draw?
Allen’s test
This indicates the hydrogen ion concentration in the blood. This determines the overall state of acid-base balance but does not indicate source
pH
This pertains to excessive hydrogen ions.
Low pH (Acidosis)
This pertains to deficit hydrogen ions.
High pH (Alkalosis)
What is the value that indicates low pH?
Below 7.35
What is the value that indicates high pH?
Above 7.45
This measures partial pressure of CO2 and indication of ventilation. This contributes to the acid level in the blood.
Partial CO2 level
What is the relationship between partial CO2 levels and respiration?
Faster the respiratory rate or deeper the depth = more CO2 is expired
What happens when you have low PCO2 below 35 mmHg?
pH increases and more alkalotic
What happens when you have high PCO2 above 45 mmHg?
pH decreases and more acidotic
This is a weak base that combines with CO2. This is often regulated by renal excretion
HCO3 or Bicarbonate
What is the relationship between HCO3 or Bicarbonate and ph levels?
Direct Relationship
What happens when you have low HCO3 below 22 mEq/L ?
pH decreases and more acidosis
What happens when you have high HCO3 above 26 mEq/L ?
pH increases and more alkalosis
What is the level of Partial Oxygen or PO2 when it is classified as mild hypoxemia?
PaO2 = 60 to 79 mmHg
What is the level of Partial Oxygen or PO2 when it is classified as moderate hypoxemia?
PaO2 = 40 to 59 mmHg
What is the level of Partial Oxygen or PO2 when it is classified as severe hypoxemia?
PaO2 < 40 mmHg
This condition pertains to low Ph and low plasma bicarbonate.
Metabolic Acidosis
What is the formula for the anion gap?
Na – (Cl + HCO3)
What is the normal value of the anion gap?
8-12 mEq/L)
What are the causes of the normal anion gap?
Direct loss of bicarbonate: diarrhea, lower intestinal fistulas, ureterostomies, diuretics, TPN without HCO3
What are the causes of the high anion gap?
Excessive accumulation of fixed acid: ketoacidosis, lactic acidosis, salicylate poisoning, uremia, ethylene glycol toxicity, starvation
What are the manifestations of metabolic acidosis?
Headache, confusion, drowsiness, increased RR and depth, N&V, decreased BP, cold, clammy skin, dysrhythmias, shock
What are the medical management entailed to correct metabolic imbalance?
u Administer bicarbonate
u Monitor potassium levels
u Treat if with low serum calcium levels
u Administer alkalinizing agents
This condition pertains to high pH and high plasma bicarbonate
Metabolic Alkalosis
What are the causes of metabolic alkalosis?
(1) Vomiting or gastric suction,
(2) pyloric stenosis
(3) loss of potassium through diuretics
(4) excessive adrenocorticoid hormones
What are the manifestations of metabolic alkalosis?
(1) Tingling in the fingers and toes
(2) dizziness and hypertonic muscles
(3) respiratory depression , atrial tachycardia,
(4) decreased motility and paralytic ileus
What are the medical management entailed to correct metabolic imbalance?
(1) monitor I&O, administer chloride
(2) restore normal fluid volume
(3) replace potassium
(4) administer H2 receptor antagonists (cimetidine) and carbonic anhydrase inhibitors (Acetazolamide)
This condition pertains to low pH and high partial carbon dioxide (PaCO2). This usually transpires due to inadequate excretion of CO2 with inadequate ventilation.
Respiratory Acidosis
What are the causes of respiratory acidosis?
(1) acute pulmonary edema,
(2) aspiration of foreign object, atelectasis,
(3) pneumothorax, overdose of sedatives
(4) sleep apnea
(5) admission of O2 to Prothrombin time with hypercapnia
(6) severe pneumonia
(7) Respiratory Distress Syndrome and degenerative disease
What are the manifestations of respiratory acidosis?
(1) increased RR, HR, BP
(2) mental cloudiness and feeling of fullness in the head,
(3) Ventricular fibrillation
(4) increased increased intracranial pressure (ICP), hyperkalemia
What is the correct (optimum) medical management of respiratory acidosis?
u Administer Oxygen with extreme caution (carbon
dioxide narcosis)
u Administer bronchodilators to reduce bronchial spasm
u Pulmonary hygiene to clear tract of mucus and
purulent drainage
u Adequate hydration (2-3L/day)
u Mechanical ventilation as indicated
This condition pertains to high pH and low partial carbon dioxide (PaCO2).
Respiratory Alkalosis
What are the causes of respiratory alkalosis?
(1) hyperventilation to include extreme anxiety,
(2) hypoxemia early phase of salicylate intoxication
(3 ) gram negative bacteremia,
(4) inappropriate ventilator settings,
(4) hepatic insufficiency and cerebral tumors
How is respiratory alkalosis manifested?
(1) lightheadness
(2) decreased cerebral
blood flow
(3) numbness and tingling, tinnitus and loss of consciousness
(4) tachycardia and ventricular/atrial dysrhythmias
What is the correct management of respiratory alkalosis?
u Correct underlying disorders
u Instructed to breathe more slowly to allow CO2 to accumulate
u A sedative may be required to relieve hyperventilation
What are the steps for ABG interpretation?
(1) Check pH
(2) Check CO2 (ROME - Respiratory Opposite; Metabolic Equal)
(3) Check PCO2
(4) Check HCO3 (HCO3 is the same or equal in both respiratory and metabolic)
(5) Check PO2
(6) Check Compensation
(7) Check Manifestations
What is the compensation for respiratory acidosis?
Increase serum HCO3 and increased renal acid secretion
What is the compensation for respiratory alkalosis?
Decreased serum HCO3 and decreased renal acid secretion
What is the compensation for metabolic acidosis?
Hyperventilation with decreased PaCO2
What is the compensation for metabolic alkalosis?
Hypoventilation with increased PaCO2
What is the normal value range of Arterial pH?
7.35-7.45
What is the normal value range of PCO2?
35-45 mmHg
What is the normal value range of PO2?
80-100 mmHg
What is the normal value range of HCO3?
22-26 mEq/L
What is the normal value range of Base Excess/deficit?
+/- 5 mEq/L
