Acid-Base Balance and Hypoxia Flashcards
What is an acid?
What is a base
Acid - Donates H+
Base - Accepts H+
What is a strong acid?
What is a weak acid?
What is a buffer?
Strong acid - completely dissociates into H+ and a weak conjugate base in aqueous solution
Weak acid - only slightly dissociates in aqueous solution and has a strong conjugate base
Buffer - a weak acid and its conjugate base that resists changes in H+ concentration when strong acid or bases are added
How is the pH calculated?
negative base of the hydrogen ion concentration
if you double H+ then pH decreases by 0.3
If you halve H+ then pH increases by 0.3
What are volatile acids and what are some examples?
What are fixed acids and what are some examples?
Volatile acids can be converted to gas and removed by the lungs (in the form of CO2)
- Glucose, Fat
Fixe acids cannot be removed from the body by the lungs and are removed by the kidney and GI tract
- Glucose (anaerobically)
- Cysteine
- Phosphoprotein
What is the Isohydric principle and some buffers of the body?
Isohydric principle - All buffer pairs in a homogeneous solution are in equilibrium with the same hydrogen ion concentration
Bicarbonate (HCO)
Phosphate (H3PO4)
Blood Proteins - especially Hgb
Interstitial fluid - mainly bicarb and some phis
Bones - mostly phis
Intracellular buffers - intracellular proteins and organic phosphates
How is CO2 transported in the blood?
H+ and HCO+ can combine into Carbonic acid, carbonic anhydrase can convert it to CO2 (liquid form) and H2O, CO2 is transported to lungs and expired
What is the Henderson – Hasselbalch Equation
and what is it used for?
What are the isobar lines?
A way to calculate the bicarb, you must have the pH and CO2
Standard blood gas machine measures this for us
If we hold the CO2 constant we can use the H-H equation to determine the HCO as the pH changes
Different isobar lines are created for different CO2 concentrations
The pH moves up and to the left with reap. acid
The pH moves right and down with reps. alk
Adding more Hgb means more HCO will be needed to change pH
What are control center depression, neuromuscular, and pulmonary causes of respiratory acidosis
1. Depression of Respiratory Control Centers Anesthetics Sedatives Opiates Brain injury or disease Severe hypercapnia, hypoxia
2. Neuromuscular disorders Spinal cord injury Phrenic nerve injury Poliomyelitis Botulism, tetanus Myasthenia gravis Administration of curare-like drugs Diseases affecting the respiratory muscles
- Pulmonary diseases
Acute asthma
Pulmonary vascular disease
What are chest awl restriction, lung restriction, pulmonary parenchymal diseases, and airway obstruction causes of respiratory acidosis?
- Chest wall restriction
Kyphoscoliosis
Extreme obesity - Lung restriction
Pulmonary fibrosis
Sarcoidosis
Pneumothorax - Pulmonary parenchymal diseases
Pneumonia
Pulmonary edema - Airway obstruction
Chronic obstructive pulmonary disease
Upper airway obstruction
What are central nervous, drug or hormone, pulmonary diseases, and other reasons for pulmonary alkalosis?
1. Central Nervous System Anxiety Hyperventilation Inflammation (encephalitis, meningitis) Cerebrovascular disease Tumors
- Drugs or hormones
Salicylates
Progesterone - Pulmonary diseases
Acute asthma
Pulmonary vascular disease (pulmonary embolism)
other:
Bacteremias, fever
Overventilation with mechanical ventilators
Hypoxia,high altitude
What are ingestion, loss of bicarb ions, and inability to excrete hydrogen ions causes of metabolic alkalosis?
1. Ingested drugs or toxic substances Methanol Alcohol Salicylates Ammonium Chloride Ethylene glycol
- Loss of bicarbonate ions
Diarrhea
Pancreatic Fistulas
Renal dysfunction - Inability to excrete hydrogen ions
Renal dysfunction
What are lactic acidosis and ketoacidosis reasons for metabolic acidosis?
- Lactic acidosis
Hypoxemia
Anemia, carbon monoxide
Shock (hypovolemic,cardiogenic, septic, etc.)
Severe exercise
Acute respiratory distress syndrome (ARDS) - Ketoacidosis
Diabetes mellitus
Alcoholism
Starvation
What are loss of hydrogen ion and ingestion of bicarb reasons for metabolic alkalosis?
1. Loss of hydrogen ions Vomiting Gastric fistulas Diuretic therapy Treatment with or overproduction of mineralocorticoids
- Ingestion or administration of excess bicarbonate
Intravenous bicarbonate
Ingestion of bicarbonate or other bases (e.g. antacids)
What is the base excess?
mEq of acid or base needed to titrate 1 liter of blood to a pH of 7.4 at 37C if the PCO2 is 40
What is the Anion Gap?
Anion Gap = NA+ - {(Cl-) + (HCO-)}
Normally 12 +/- 4 and used in deterring metabolic acidosis The difference between measured anions and the unmeasured cations If greater than 16 - Lactic acidosis - ketoacidosis - organ anions - renal retention of sulfate - phosphate - urate Decreased K, Ca, and/or Mg
