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)
