Acid Base Imbalance Flashcards
Do acids donate or accept hydrogen ions when dissolved in water?
Donate
Do alkalis donate or accept hydrogen ions when dissolved in water?
Accept
What can buffers do in relation to hydrogen ions?
They can bind or release hydrogen ions in solution
What is the main extracellular buffering system?
The bicarbonate buffer system
H2O + CO2 ⇌ H2CO3 ⇌ H+ + HCO3-
Which enzyme facilitates the conversion of H2O and CO2 into H2CO3 and back again within the bicarbonate buffer system?
Carbonic Anhydrase
What is the main intracellular buffering system?
The ammonia/phosphate buffer system
HPO4- + H+ ⇌ H2PO4
NH3 + H+ ⇌ NH4+
How can proteins act as buffers?
Some amino acids contain Carboxyl and Amino groups that can act as weak acids and bases
Haemoglobin can buffer extra H+ ions
What is the normal blood pH range?
7.35-7.45
What is a blood pH lower than 7.35 known as?
Alkalosis
What is a blood pH higher than 7.45 known as?
Acidosis
When taking into account compensation, what is the exact normal value for blood pH?
7.4
What is the normal range of partial pressure for CO2 in arterial blood?
4.6-6.0kPa
If blood partial pressure of CO2 increases, what happens to blood pH?
It decreases, becoming more acidic
If blood partial pressure of CO2 decreases, what happens to blood pH?
It increases, becoming more basic
Will hyperventilation cause the partial pressure of CO2 in blood to increase or decrease?
Decrease, as CO2 is being expelled from the body faster due to the faster breathing rate
Will hypoventilation cause the partial pressure of CO2 in blood to increase or decrease?
Increase, as CO2 is being expelled from the body slower due to the slower breathing rate
What is the normal range of partial pressure for O2 in arterial blood?
10-14kPa
What is a blood O2 partial pressure below 10kPa called?
Hypoxemia
What is the normal range of HCO3- concentration in arterial blood?
22-26 mEq/L
If blood concentration of HCO3- increases, what happens to blood pH?
It increases, becoming more basic
If blood concentration of HCO3- decreases, what happens to blood pH?
It decreases, becoming more acidic
What is a healthy oxygen saturation level?
Greater than 95%
What does an oxygen saturation level below 93% indicate?
Hypoxemia, low blood O2 partial pressure
What is the difference between Hypoxia and Hypoxemia?
Hypoxia refers to the reduced oxygenation of tissues, whereas hypoxemia refers to a low blood partial pressure of oxygen
How is the respiratory system involved in acid base balance?
H2O + CO2 ⇌ H2CO3 ⇌ H+ + HCO3-
It works via the CO2
How is the renal system involved in acid base balance?
H2O + CO2 ⇌ H2CO3 ⇌ H+ + HCO3-
It works via the HCO3-
Is the renal system slower or faster than the respiratory system when it comes to compensating?
Slower
How does the renal system respond to blood pH changes?
It alters the rate of H+ and HCO3- secretion and absorption depending on pH
What are the steps to acid/base balance interpretation?
- Is pH normal?
- Is PaCO2 normal?
- Is HCO3- normal?
- Does PaCO2 or HCO3- match pH?
- Does the PaCO2 or the HCO3- go the opposite direction of the pH?
- Is the PaO2 and the Oxygen saturation normal?
What are some causes of metabolic acidosis?
Diabetic ketoacidosis Diarrhoea Renal failure Shock induced hypoxemia Aspirin overdose Sepsis Starvation Exercise without sufficient caloric intake (lactic acidosis)
What are some symptoms of metabolic acidosis?
Anorexia, Nausea and Vomiting
General malaise (feeling “ugh”), fatigue
Weakness, reduced deep tendon reflexes (knee reflex hammer test)
Warm, flushed skin and mucous membranes
Tachycardia –> increased cardiac output (could lead to tired myocardium, bradycardia and decreased cardiac output and bp, also dysrhythmia)
Kussmaul’s respirations (deep and rapid breaths)
Decreased levels of consciousness (confusion, stupor and coma)
Possibly increased potassium and decreased magnesium
What are some treatments for metabolic acidosis?
Hydration (especially if diarrhoea and vomiting)
Correct the issue (e.g. insulin, antidiarrheal medications, dialysis)
Sodium bicarbonate (not routinely given anymore)
What are some causes of metabolic alkalosis?
Excess base production Loss of gastric secretions (e.g. vomiting) Overuse of antacids Potassium wasting diuretics Blood transfusions (sometimes) Thiazide diuretics
What are some symptoms of metabolic alkalosis?
Confusion and reduced levels of consciousness
Blood pressure drop, seizures
Tingling and numbness around mouth, fingers and toes
Shallow Bradypnea
What are some treatments for metabolic alkalosis?
Treat underlying cause
Antiemetic medications (anti vomiting and nausea)
Monitor electrolytes and replace as indicated
Seizure precautions
What are some causes of respiratory acidosis?
Failure of lungs to eliminate CO2 Hypoventilation Chronic Obstructive Pulmonary Disease (COPD) Airway obstruction Drug overdose Chest or head trauma Pulmonary oedema Neuromuscular disease Respiratory depression (induced hypoventilation by narcotics and analgesics e.g. morphine) Alveolar disorders
What are some symptoms of respiratory acidosis?
Headache, confusion, irritability and decreased level of consciousness
Weakness, decrease in deep tendon reflexes (knee reflex hammer test)
Tachycardia –> increased cardiac output (could lead to tired myocardium, bradycardia and decreased cardiac output and bp, also dysrhythmia)
Ineffective respiratory efforts
What are some treatments for respiratory acidosis?
Maintain patient airway and enhance ventilation
- Oxygen
- Pulmonary toilet (get gunk out of lungs)
- Ventilatory support (Endotracheal tube)
- Frequent blood monitoring
- Medication
Assess level of consciousness frequently
Low carb, high fat diet
What are some causes of respiratory alkalosis?
Lungs eliminate too much CO2 Hyperventilation Hypoxemia (leads to hyperventilation, blowing out CO2) Panic, anxiety Neurogenic disorders Asthma (hyperventilation) Salicylate toxicity
What are some symptoms of respiratory alkalosis?
Rapid, deep respiration
Anxiety, irritability, lightheadedness
Tetany/carpopedal spasm (claw hands), seizures
Pins and needles (Paresthesia)
Decreased calcium –> Ckvostek sign (twitching of facial muscles in response to tapping over area of facial nerves)
Muscle cramping, weakness
Tachycardia, may be hypotensive, palpitations
Skin and mucous membranes are pale to cyanotic (blue/grey skin)
What are some treatments for respiratory alkalosis?
Monitor due to possibility of respiratory failure
Decrease respiratory rate
- Focused breathing
- Decreased breaths per minute on ventilator
- Oxygen therapy
Anti anxiety medications (paper bags included)
