Acidosis and Alkalosis Flashcards
Hypoxemia is dependent on 3 variables
- Ventilation
- Diffusion
- Perfusion
Parts of respiratory assessment- Inspection
o Rate and rhythm o Mentation o Work of breathing o Skin colour o Clubbing (long term)
Parts of respiratory assessment- palpation
o Thumbs at spine, inhale and look for equal separation/expansion
o Tracheal shift
Parts of respiratory assessment- auscultation
o Wet Sounds • Coarse crackles (fluid) • Fine Cackles o Dry Sounds • High and low pitch wheezes
How do you landmark lung bases?
o (C7= prominent, bases are T10-T12
What is the difference between restrictive and obstructive respiratory issue?
Difference between restrictive and obstructive?
• Obstructive= airway narrowing
• Restrictive= limited movement (expansion)
o Intrinsic- Fibrosis or edema
o Extrinsic- Obesity or pregnancy
Normal ABG Values - 02, pH, pCO2, HCO3
Normal ABG Values • PH- 7.35-7.45 • Normal pC02- 35-45mmHg (Low = ALKALOSIS) • Normal HCO3 24-32mmhg (Low= ACIDOSIS) • p02- 80-100 mmhg
Describe ABG of METABOLIC ACIDOSIS
2 subtypes?
• pH low, pc02 low (if compensating) HCO3 Deficit
o Normal Anion Gap= 8-12mmol/L
o IF normal Anion gap= Direct losses (renal issue, diarrhea, diuretic)
o If High Anion gap= issue is fixed acid (ex. lactic or ketoacidosis)
Describe ABG of METABOLIC ALKALOSIS
• pH High, HCO3 excess (High) (or loss of H+), (pC02 High compensating)
Most common cause of metabolic alkalosis
- Most common cause of metabolic alkalosis is vomiting or gastric suction with loss of H+ and Cl+ atoms.
- Also Associated with loss of potassium
What is the role the kidney in acid- base balance
- Renal compensation is relatively slow.
- Regulates the bicarbonate level in the ECF. Kidneys regenerate bicarbonate ions and reabsorb them from the canal tubular cells.
- During Acidosis: the kidneys excrete hydrogen ions and conserve bicarbonate ions to help restore balance.
- During Alkalosis: the kidneys retain hydrogen ions and excrete bicarbonate ions to help restore balance.
- This process cannot compensate for acidosis created by renal failure.
Role of respiratory system in acid base balance
- Controlled by the medulla.
- Lungs control Carbon Dioxide (CO2), and thus the carbonic acid content of the ECF. By adjusting ventilation in response to the amount of CO2 in the blood.
- ↑ in partial pressure of CO2 in arterial blood (PaCO2) is a powerful stimulant to respiration.
- During Metabolic Acidosis: respiratory rate increases, causing greater elimination of CO2 and decrease in acid load.
- During Metabolic Alkalosis: respiratory rate decreases, causing CO2 to be retained and increases the acid load.
What do you see clinically in Metabolic acidosis
- Clinical Manifestations: headache, confusion, drowsiness, ↑Respiratory rate and depth, nausea, and vomiting. Peripheral vasodilation and decreased cardiac output occur when the pH drops to less than 7.
- Physical Assessment findings: ↓blood pressure, cold and clammy, dysrhythmias, shock.
- Chronic metabolic acidosis is usually seen with chronic renal failure.
What do you see clinically in Metabolic Alkalosis
• Most common cause of metabolic alkalosis is vomiting or gastric suction with loss of H+ and Cl+ atoms.
•Other causes of metabolic alkalosis:
o Loss of potassium (non-potassium sparring diuretics).
o Excessive adrenocorticoid hormones (Cushing’s syndrome).
• Manifestations:
o Tingling of fingers/toes.
o Dizziness
o Hypertonic muscles
o Respirations ↓ as a compensatory action (attempt to ↑ CO2).
o Atrial tachycardia may develop.
o ↓K+ levels, resulting in premature U waves (contractions) on ECG.
Tx for metabolic alkalosis
o Restore normal fluid volume by administering NaCl- (further volume depletion perpetuates the alkalosis.
o If patient is Hypokalemic, potassium is administered as KCl to replace both K+ and Cl- losses.
o H2 Receptor Antagonists to reduce production of gastric HCl.
ABG’s of Respiratory Acidosis
ph low, pC02 high, HCo3 (high if compensating)
• Clinical disorder in which pH is less than 7.35 and the PaCO2 is
What do you see clinically in Respiratory Acidosis.
With what condition might this occur
• Manifestations: o ↑ pulse and respiration rate o ↑ blood pressure o mental cloudiness o feeling of fullness in the head o Severe: intracranial pressure o Hyperkalemia may result as H+ ions move into cells causing a shift of K+ out of the cell
Conditions: o Acute pulmonary edema. o Aspiration of a foreign object. o Atelectasis. o Pneumothorax o Sedative overdose. o Sleep apnea o Severe pneumonia o Acute respiratory distress syndrome (ARDS
Tx for Respiratory Acidosis
o Directed at improving ventilation; exact measures vary with the cause of inadequate ventilation.
o Bronchodilators help reduce bronchial spasm.
o Supplemental oxygen
o Appropriate mechanical ventilation
o Important to slowly decrease PaCO2.
o Semi-fowlers position facilitates expansion of the chest wall.
ABG’s of Respiratory Alkalosis
pH high, pC03 low, HC03 (low if compensating)
- Respiratory alkalosis is a clinical condition in which the pH is greater that 7.45 and the PaCO2 is > 38mmHg.
- Respiratory alkalosis in always caused by hyperventilation, which causes excessive “blowing off” of CO2, decreasing the carbonic acid concentration.
Causes of Respiratory Alkalosis?
Manifestations
o Extreme anxiety.
o Hypoxemia
o Early phase salicylate intoxication
o Inappropriate ventilator settings that do not match pt. requirements.
o Light-headedness d/t vasoconstriction and ↓cerebral blood flow.
o Inability to concentrate.
o Numbness and tingling from decreased calcium ionization.
o Tinnitus (ringing in the ears).
o Loss of consciousness
o Tachycardia
o Ventricular and atrial dysrhythmias.
Tx of Respiratory Alkalosis
o Treat the underlying cause.
o Breath more slowly to allow CO2 to accumulate or breath into a paper bag.
o Sedatives may be required to relieve hyperventilation in very anxious patients.
Describe hypoxemia in terms of p02 levels
Normal pO2 is 80-100 mm Hg when measure on room air
60-80 mild hypoxemia
40-60 moderate hypoxemia
Less then 40 severe hypoxemia
How do you know if respiratory acidosis/alkalosis has begun recently?
If kidneys have begun compensation, it has happened in the last 12 hrs.
What is a normal anion gap? what does an abnormal one tell you
o Normal Anion Gap= 8-12mmol/L
o IF normal Anion gap= Direct losses (renal issue, diarrhea, diuretic)
o If High Anion gap= issue is fixed acid (ex. lactic or ketoacidosis)
How does pH effect acidity
Very Generally…
Metabolic acidosis from direct losses (GI loss or kidney disfunction) leads to inc in relative concentration of K in plasma. Related to acid being buffered in cells. (K+ out, H+ in).
Likely likely to occur in Respiratory acidosis
DKA also inc relative K, but more so due to hyperosmolarity.
Hypokalemia can be masked by this phenomenon as it cause blood K to appear normal
What can bring on lactic acid?
anything that causes hypoxia.
Limited 02, overexertion, RBC deficiencies, etc
You have metabolic acidosis… uncompensated means pCO2 is…
PC02 Normal- Not compensating
You have metabolic acidosis… partial compensation means pCO2 is…
pC02 Moved in opposite ph direction… BUT pH is still abnormal
You have metabolic acidosis… fully compensated means pCO2 is…
pCo2 moved a lot in opposite pH direction and pH is Normal
Someone with metabolic acidosis will likely have what K measure.
What happens when you deal with acidosis?
High K. Related to H pushing K out of cells.
K flows back into cells and K drops FAST.
Might consider some KCL later
PC02 does what to which vessels
cerebral vasodilator.
