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44 Cards in this Set
- Front
- Back
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Pyramid points
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-In acidosis the pH is down
-In alkalosis the Ph is up -The respiratory function indicator is the Pco2 -The metabolic function indicator is the bicarbonate ion HCO3 |
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Pyramid Step 1
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Look at the blood gas report. Look at the pH. Is the pH up or down? If the pH is up, it reflects alkalosis. if the pH is down, it reflects acidosis
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Pyramid Step 2
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Look at the Pco2. is the Pco2 up or down? If the Pco2 reflects an opposite response to the pH, then you know that the condition is a respiratory imbalance. if the Pco2 does not reflect an opposite response to the pH, then move on to Pyramid Step 3
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Pyramid Step 3
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Look at the bicarbonate concentration, HCO3. Does the bicarbonate concentration reflect a corresponding response with the pH? If it does, then the condition is a metabolic imbalance
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Pyramid Step 4
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Remember, compensation has occurred if the pH is in a normal range of 7.35 to 7.45. if the pH is not within normal range, look at the respiratory or metabolic funtion indicators
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Respiratory Imbalances
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If the condition is a respiratory imbalance, look at the bicarbonate concentration to determine the state of compensation
-If the bicarbonate concentration is normal, then the condition is uncompensated. if the bicarbonate concentration is abnormal, then the condition is PARTIAL COMPENSATION |
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Metabolic Imbalances
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`If the condition is a metabolic imbalance, look at the Pco2 to determine the state of compensation
- If the pco2 is normal, then the condition is uncompensated. if the Pco2 is abnormal, then the condition is partial compensation |
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What is normal?
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Values at sea level:
Partial pressure of oxygen (PaO2) - 75 - 100 mm Hg Partial pressure of carbon dioxide (PaCO2) - 35 - 45 mm Hg A pH of 7.35 - 7.45 Oxygen saturation (SaO2) - 94 - 100% Bicarbonate - (HCO3) - 22 - 26 mEq/liter |
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Low pH
High pH Low/High Pco2 bicarbonate HCO3 |
acidosis
alkalosis if pH is up, Pco2 down=respir. if pH is down,Pco2 up =respir. if HCO3 is up & pH is up=metabolic vs versa |
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Determining Respiratory Imbalance
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look at bicarb HCO3 concentration:
if normal then uncompensated if abnormal then partial compensation |
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Determining Metabolic Imbalance
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look at Pco2
if normal then uncompensated if abnormal then partial comp. |
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What is compensated?
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a return to normal by compensatory mechanisms
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Causes of respiratory alkadosis(hypocapnia)?
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is hypoxia, then anxiety, fever, pain, sepsis, hepatic failure, CNS disorders (stroke, infections)pulmonary disorders without hypoxia, delirium tremens & drugs (aspirin toxicity)
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Causes of Metabolic Alkalosis?
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loss of acid, addition of alkali or both in the kidneys or elsewhere. response to long-standing hypercapnia, kypokalemia, diuretic use
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Causes of Metabolic acidosis?
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treatment of cause. perfusion of tissues resulting in accumulation of lactic acid.
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Causes of Respiratory acidosis(hypercapnia)?
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from build-up of carbon dioxide in bl.due to hypoventilation-
-drug depression of resp.center -CNS trauma, MI, -Hypoventilation of obesity -cervical cord trauma or lesions -Poliomyelitis -Tetanus -cardiac arrest w/cerebral hypoxia -Guillain-Barre syndrome Muscle relaxant drugs Acute COAD |
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Distinquishing btw Respiratory acidosis and Metabolic acidosis:
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In resp. Co2 is increased while HCO3 is either normal(uncompensated) or increased (compensated)
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Respiratory alkalosis...
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hyperventilation
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Metabolic alkalosis...
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is most common acid-base disorder -loss of hydrogen ions which leads to increased bicarb & Co2 concentrations.
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Table 3. Respiratory and renal compensation in acid-base imbalance (5)
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Acid-base imbalance -Carbon-dioxide (mm Hg)- Plasma bicarbonate (mmol/L)
1.Metabolic acidosis Compensates (decreases) by 1.25 x X Decreases by X 2.Metabolic alkalosis Compensates (increases) by 0.75 x X Increases by X 3.Acute respiratory acidosis Increases by X Compensates (increases) by 0.1 x X 4.Chronic respiratory acidosis Increases by X Compensates (increases) by 0.4 x X 5.Acute respiratory alkalosis Decreases by X Compensates (decreases) by 0.2 x X 6.Chronic respiratory alkalosis Decreases by X Compensates (decreases) by 0.4 x X |
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Table
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Respiratory Acidosis
Acute < 7.35 > 45 Normal Partly Compensated < 7.35 > 45 > 26 Compensated Normal > 45 > 26 -------------------------------------------------------------------------------- Respiratory Alkalosis Acute > 7.45 < 35 Normal Partly Compensated > 7.45 < 35 < 22 Compensated Normal < 35 < 22 -------------------------------------------------------------------------------- Metabolic Acidosis Acute < 7.35 Normal < 22 Partly Compensated < 7.35 < 35 < 22 Compensated Normal < 35 < 22 -------------------------------------------------------------------------------- Metabolic Alkalosis Acute > 7.45 Normal > 26 Partly Compensated > 7.45 > 45 > 26 Compensated Normal > 45 > 26 -------------------------------------------------------------------------------- |
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Mixed disorders
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It's possible to have more than one disorder influencing blood gas values. For example ABG's with an alkalemic pH may exhibit respiratory acidosis and metabolic alkalosis. These disorders are termed complex acid-base or mixed disorders
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Chart
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The following chart summarizes the relationships between pH,
PaCO2 and HCO3 pH-- PaCO2-- HCO3 Respiratory Acidosis ↓ ↑ normal Respiratory Alkalosis ↑ ↓ normal Metabolic Acidosis ↓ normal ↓ Metabolic Alkalosis ↑ normal ↑ |
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If pt has pH of 7.22 & PaCO2 of 55 & HCO3 of 25
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Respirtory acidosis
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If pt has pH of 7.50 & Paco2 of 42 & HCO3 of 33
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Metabolic Alkalosis
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What are the primary buffer systems in the body?
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Kidneys and Lungs
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If a pt has an acid/base disorder that is uncompensated or partially compensated then the pH would be?
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outside the normal range
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In fully compensated states, the pH has returned to normal. Can the other values still be abnormal?
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yes
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In an uncompensated state, the pH and Paco2 move in opposite directions. What is happening if both are moving in the SAME direction?
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the primary problem would be metabolic. the decreasing Paco2 indicates that the lungs are trying to compensate. When the pH is not brought back to normal then PARTIAL RESPIRATORY compensation has happened
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What is happening if both pH and Paco2 are moving in OPPOSITE directions?
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primary acid-base disorder is RESPIRATORY. the kidneys would act as a buffer and try to compensate by retaining HCO3 while trying to return the pH to normal
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Partially compensated table
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Partially Compensated States
pH PaCO2 HCO3 - Respiratory Acidosis ↓ ↑ ↑ Respiratory Alkalosis ↑ ↓ ↓ Metabolic Acidosis ↓ ↓ ↓ Metabolic Alkalosis ↑ ↑ ↑ |
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if pt has pH 7.32, Paco2 of 32 & HCO3 of 18?
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Metabolic Acidosis- PARTIALLY COMPENSATED
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If pt has pH of 7.35, Paco2 of 48 & HCO3 of 28?
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Respiratory Acidosis- PARTIALLY COMPENSATED
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If pt has pH of 7.33, Paco2 of 62 & Hco3 of 35 then?
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Partially compensated Respiratory Acidosis
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If pt has pH of 7.43, Paco2 of 48 & Hco3 of 36 then?
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fully compensated Metabolic Alkalosis
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Full chart
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pH PaCO2 HCO2
R.ac:dec inc N R.al:inc dec N M.ac:dec N dec M.al:inc N inc Partially compensated: R.ac:dec inc inc R.al:inc dec dec M.ac:dec dec dec M.al:inc inc inc Fully compensated: R.ac: N inc inc R.al: N dec dec M.ac: N dec dec M.al: N inc inc |
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Cations
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Calcium
Magnesium Potassium Sodium |
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Anions
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Bicarbonate HCO#-
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Extracellular fluids
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NA, CL HCO3
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Intracellular fluids
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Mg & K+ (cations)
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regulation of electrolytes
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K & Ca are stored in bones & cells
NA & CL not stored |
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Normal
Na K Ca Mg |
135-145 mEq/L
3.5 - 5 mEq/L 1 gram a day 1.3 - 2.1 mEq/L-in plasma |
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Metabolic Acidosis
Metabolic Alkolosis |
low bicarb level-all low,
high bicarb level-all high, |
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Respiratory acidosis
Respiratory alkalosis |
high PaCo2- low ph,high Paco2, high/normal HCO3
low PaCO2-high ph,low Paco2,low HCO3 |
