ABG Flashcards
What does pH measure in the blood?
Acidity or Alkalinity
What is the normal blood pH range?
7.35 to 7.45
The more H+ in the blood the ____ the pH
Lower (acidic)
The less H+ in the blood the ____ the pH
Higher (alkaline)
In an Acidic State there is either too much _____ or too little ____
Too much PaCO2; too little HCO3
In an Alkalotic State there is either too much _____ or too little ____
Too little PaCO2; too much HCO3
In an Acidic State what body functions begin to change?
Weak cardiac contractions, decreased vascular response to catecholamines, diminshed response to some meds
In an Alkalotic State what body functions are interfered with?
Tissue oxygenation, neuromuscular, and neurological functioning
Blood pH changes in according to the level of which acid?
Carbonic Acid (H2CO3)
What is the compensation for too much or too little Carbonic Acid?
Increase or decrease in rate and depth on ventilation
How long does the “quick compensation” of ventilatilatory change last for
1-3 minutes
What are the two buffers systems?
Respiratory buffer, Renal buffer
Carbonic Acid is part of which buffer system?
Respiratory
What is the acid involved in the respiratory buffer system?
Carbonic Acid (H2CO3)
What is the base involved in the Renal buffer system?
Bicarbonate (HCO3)
What do the kidneys excrete or retain as part of the Renal buffer system?
Bicarbonate (HCO3)
What do the kidneys do when there is an alkaline pH in the blood?
Excrete Bicarbonate (HCO3) into urine
The more acidic the pH what do they kidneys do?
Keep Bicarbonate (HCO3) which is a base and helps balance
What is the time frame of the Renal buffer system?
Hours to days
What is the time frame of the Respiratory Buffer system vs the Renal Buffer system?
Resp: 1-3 minutes; Renal: hours to days
Acidosis is when the pH is lower than what?
7.35
Alkalosis is defined as a pH above what?
7.45
What are the two measures of Respiratory Acidosis?
pH less than 7.35 and PaCO2 greater than 45mmHg
What are the two measures of Respiratory Alkalosis?
pH greater than 7.45 and PaCO2 less than 35mmHg
Accumulated CO2 combines with water and forms what?
Carbonic Acid (H2CO3) which lowers pH
Respiratory Acidosis is due to an accumulation of what?
CO2, which combines with water and forms Carbonic Acid (H2CO3) and lowers pH
What type of breathing can cause Respiratory Acidosis?
Hypoventilation
Hypoventilation can cause a build up of what?
CO2, which combines with water to make Carbonic Acid (H2CO3) and lowers pH
What type of breathing can result in Respiratory Alkolosis?
Hyperventilation
Hyperventilation can lead to what?
Respiratory Alkolosis
What are the two measures for Metabolic Acidosis?
pH less than 7.35 and Bicarbonate (HCO3) less than 22
Metabolic Acidosis is caused by a deficit of ____ or an excess of ___
Deficit of base; excess of acid other than CO2
Which compound does Metabolic Acidosis not take into account?
CO2
What can cause a deficit of base leading to Metabolic Acidosis?
Diarrhea, intestinal fistulas
Metabolic Alkolosis is measured by which two values?
pH greater than 7.45 and Bicarbonate (HCO3) greater than 26
Metabolic Alkolosis can be caused by what two things?
Too much base (too much antacid) or loss of acid (puking, diuretics)
What is PaCO2?
Partial Pressure of Carbon Dioxide that is dissolved
What is a normal PaCO2 range?
35-45
A PaCO2 greater than 45 means what for the pH?
Acidosis
A PaCO2 greater than 35 means what for the pH?
Alkolsis
What is PaO2?
Partial Pressure of Oxygen that is dissolved
What is the normal PaO2 range?
80-100 mmHg
What is HCO3?
Bicarbonate.
What is the normal HCO3 (bicarbonate) range?
22-26 mEq/L
HCO3 (bicarbonate) greater than 27 means what?
Alkalosis
HCO3 (bicarbonate) less than 21 means what?
Acidosis
What is SaO2?
Arterial Oxygen saturation
What is a normal Sa02 range?
95-100%
An ABG with the following values means what? pH=7.49, PaCO2=43, HCO3=32
pH is high (alkalotic), PaCO2 is slightly high (acidotic), HCO3 is high (alkalotic). Metabolic Alkalosis. The PaCO2 is rising in an attempt to compensate the alkaline environment as CO2 is acidic.
If pH and HCO3 are both high is this Respiratory or Metabolic Alkalosis?
Metabolic Alkalosis. HCO3 is controlled by kidneys so an evelated Bicarbonate means the metabolic system (aka kidneys) is involved
If pH and HCO3 are both low is this Respiratory or Metabolic Acidosis?
Metabolic Acidosis. HCO3 is controlled by kidneys. When HCO3 (Bicarbonate) is low and pH is low you have Metabolic Acidosis.
What are the basic steps in interpreting an ABG?
1 check pH for acidic/basic/normal. 2 check PaCO2 for acidic/basic/normal. 3 check HCO3 for acidic/basic/normal. If pH and CO2 are opposite one another but HCO3 is normal then Respiratory. If pH and HCO3 are both high or low then Metabolic.
If pH and CO2 are opposite then the the issue is Respiratory or Metabolic?
Respiratory
If pH and HCO3 are both high or both low then the issue is Respiratory or Metabolic?
Metabolic.
What is “compensation”?
When CO2 tries to compensate for Metabolic Acidosis or Metabolic Alkalosis.
If pH is 7.8 and HCO3 is 32 is this respiratory or metabolic alkalosis? If CO2 is 45 what is happening?
Metabolic Alkalosis. Elevated CO2 increased acidity and “compensates” for alkalosis.
An elevated CO2 in the presence of very high pH and HCO3 means what?
Metabolic Alkalosis with compensation
Low pH and low HCO3 means what?
Metabolic Acidosis
Low pH, high CO2, and normal HCO3 means?
Respiratory Acidosis
High pH, low CO2, and normal HCO3 means?
Respiratory Alkalosis
Low pH, normal CO2, low HCO3 means?
Metabolic Acidosis without compensation
Would the CO2 be high or low during compensation during Metabolic Acidosis
Low CO2
Would the CO2 be high or low during compensation during Metabolic Alkalosis
CO2 would be high
pH 7.33, pCO2 60, HCO3 34
Resp Acidosis with metabolic compensation.
pH 7.48, pCO2 42, HCO3 30
Metabolic Acidosis with no CO2 compensation
pH 7.38, pCO2 38, HCO3 24
Normal
pH 7.21, pCO2 60, HCO3 24
Resp Acidosis with no metabolic compensation
pH 7.48, pCO2 28, HCO3 20
Respiratory Alkalosis with metabolic compensation
pH 7.50, pCO2 29, HCO3 24
Respiratory Alkalosis with no metabolic compensation
pH 7.28, pCO2 40, HCO3 18
Metabolic Acidosis with no CO2 compensation
pH 7.45, pCO2 26, HCO3 16
Respiratory Alkalosis with metabolic compensation