Arterial Blood Gas

Causቤተ መጻሕፍቲ ባይዱs
1. 2. 3. 4. 5. Central nervous system depression r/t medications such as narcotics, sedatives, or anesthesia. Impaired muscle function r/t spinal cord injury, neuromuscular diseases, or neuromuscular blocking drugs. Pulmonary disorders such as atelectasis, pneumonia, pneumothorax, pulmonary edema or bronchial obstruction Massive pulmonary embolus Hypoventilation due to pain chest wall injury, or abdominal pain.
Management
• Resolve the underlying problem • Monitor for respiratory muscle fatigue • When the respiratory muscle become exhausted, acute respiratory failure may ensue
Respiratory alkalosis
• Psychological responses, anxiety or fear. • Pain • Increased metabolic demands such as fever, sepsis, pregnancy or thyrotoxicosis. • Medications such as respiratory stimulants. • Central nervous system lesions
Signs/symptoms
• CNS: Dizziness, lethargy disorientation, siezures & coma. • M/S: weakness, muscle twitching, muscle cramps and tetany. • Nausea, vomiting and respiratory depression. • It is difficult to treat.
What is an ABG
Arterial Blood Gas Drawn from artery- radial, brachial, femoral
It is an invasive procedure.
Caution must be taken with patient on anticoagulants. Arterial blood gas analysis is an essential part of diagnosing and managing the patient’s oxygenation status, ventilation failure and acid base balance.
The Renal Buffer Response
• The kidneys excrete or retain bicarbonate(HCO3-). • If blood pH decreases, the kidneys will compensate by retaining HCO3 • Renal system may take from hours to days to correct the imbalance.
The Respiratory buffer response
• The blood pH will change acc.to the level of H2CO3 present. • This triggers the lungs to either increase or decrease the rate and depth of ventilation • Activation of the lungs to compensate for an imbalance starts to occur within 1-3 minutes
Signs & symptoms
• CNS: Light Headedness, numbness, tingling, confusion, inability to concentrate and blurred vision. • Dysrhythmias and palpitations • Dry mouth, diaphoresis and tetanic spasms of the arms and legs.
Arterial blood gas
By
Mrs. Amala Rajan Reader Medical Nursing Dept
“Life is a struggle, not against sin, not against the Money Power, not against malicious animal magnetism, but against hydrogen ions." H.L. MENCKEN
Sign & symptoms
• CNS: Headache, confusion and restlessness progressing to lethargy, then stupor or coma. • CVS: Dysrhythmias • Kussmaul’s respirations • Warm, flushed skin as well as nausea and vomiting
Management
• Increase the ventilation. • Causes can be treated rapidly include pneumothorax, pain and CNS depression r/t medication. • If the cause can not be readily resolved, mechanical ventilation.
Management
• Treat the cause • Hypoxia of any tissue bed will produce metabolic acids as a result of anaerobic metabolism even if the pao2 is normal • Restore tissue perfusion to the hypoxic tissues • The use of bicarbonate is indicated for known bicarbonate - responsive acidosis such as seen with renal failure
Acid/Base Relationship
H2O + CO2

H2CO3
HCO3 + H+
Buffers
There are two buffers that work in pairs H2CO3 Carbonic acid NaHCO3 base bicarbonate
These buffers are linked to the respiratory and renal compensatory system
Signs & symptoms of Respiratory Acidosis
• Respiratory : Dyspnoea, respiratory distress and/or shallow respiration. • Nervous: Headache, restlessness and confusion. If co2 level extremely high drowsiness and unresponsiveness may be noted. • CVS: Tacycardia and dysrhythmias
ACID BASE DISORDER
Res. Acidosis • is defined as a pH less than 7.35 with a paco2 greater than 45 mmHg. • Acidosis –accumulation of co2, combines with water in the body to produce carbonic acid, thus lowering the pH of the blood. • Any condition that results in hypoventilation can cause respiratory acidosis.
What Is An ABG?
pH [H+] PCO2 Partial pressure CO2 PO2 O2 Partial pressure
HCO3 Bicarbonate
BE Base excess
SaO2 Oxygen Saturation
Acid/Base Balance
The pH is a measurement of the acidity or alkalinity of the blood. It is inversely proportional to the no. of (H+) in the blood. The normal pH range is 7.35-7.45. Changes in body system functions that occur in an acidic state decreases the force of cardiac contractions, decreases the vascular response to catecholamines, and a diminished response to the effects and actions of certain medications. An alkalotic state interferes with tissue oxygenation and normal neurological and muscular functioning. Significant changes in the blood pH above 7.8 or below 6.8 will interfere with cellular functioning, and if uncorrected, will lead to death.
Metabolic alkalosis
• Bicarbonate more than 26m Eq /L with a pH more than 7.45 • Excess of base /loss of acid can cause • Ingestion of excess antacids, excess use of bicarbonate, or use of lactate in dialysis. • Protracted vomiting, gastric suction,hypchoremia,excess use of diuretics, or high levels of aldesterone.
Metabolic Acidosis
• Bicarbonate less than 22mEq/L with a pH of less than 7.35. • Renal failure • Diabetic ketoacidosis • Anaerobic metabolism • Starvation • Salicylate intoxication