Acid/Base Flashcards
ABGs are frequently used to detect and monitor indices of what 3 things?
- Oxygenation
- Ventilation
- Acid-base balance
ABGs quantify levels of _____ & ______.
- carboxyhemoglobin
- methemoglobin
ABG
- Blood is drawn usually from what artery?
- Sometimes drawn from what other 2 arteries?
- Blood is collected with _____ and placed on ice and taken quicky to lab for prompt analysis
- Results are usually back within _____.
- Radial
- Brachial or femoral aa
- anticoagulant (heparin)
- 5 - 15 mins
Oxygenation
- The pO2 is just used in determining ____.
- NOT in the determination of _____.
- Is pO2 from ABG or pulse ox more reliable way to check oxygenation?
- How well pt is oxygenating
- NOT: acid base conditions
- pO2 from ABG is more reliable than pulse ox.
- Body maintains precise control of ____ to maintain homeostasis
- ____ are used to keep pH in narrow range.
- Hydrogen ions
- Buffer systems
- Acidemia is pH <____
- Alkalemia is pH >____
- <7.35
- >7.45
pH of blood
Acidemia & Alkalemia
Acid/Base Disorder
Acidosis & Alkalosis
Tx for acid/base disturbances?
Management of underlying disease
(can have up to 3 disorders)
- 2 types of compensation for acid/base disorders?
- Which one is rapid and which is slow?
- Respiratory compensation (rapid)
- Metabolic compensation (days - weeks)
Acid/Base
- A primary respiratory problem involves ___
- If greater than ___ is acidosis
- If less than ____ is alkalosis
- pCO2
- >45 = acidosis
- <35 = alkalosis
Acid/Base
- Primary metabolic problem involves ____.
- If greater than ___ is alkalosis
- If less than ____ is acidosis
- pH: >7.45
- Disturbance: decreased pCO2 (<35)
- Secondary response: decreased HCO3
Respiratory Alkalosis
- pH: >7.45
- Disturbance: increased HCO3 (>26)
- Secondary response: increased pCO2
Metabolic Alkalosis
- pH: <7.35
- Disturbance: increased pCO2 (>45)
- Secondary response: increased HCO3
Respiratory acidosis
- pH: <7.35
- Disturbance: decreased HCO3 (<22)
- Secondary response: decreased pCO2
Metabolic acidosis
If both pCO2 and HCO3 are HIGH, what could it be?
- Respiratory acidosis
- Metabolic alkalosis
If both pCO2 and HCO3 are LOW, what could it be?
- Respiratory alkalosis
- Metabolic acidosis
If pCO2 and HCO3 are moving in opposite directions, there is what?
Mixed disorder is present
What causes high anion gap metabolic acidosis?
- Methanol
- Uremia
- DKA
Propylene glycol - Iron/Isoniazid
- Lactate
- Ethanol/ethylene glycol
- Salicylates/starvation
(MUDPILES)
Causes of non-anion gap metabolic acidosis
- GI bicarbonate loss
- Renal bicarbonate losses
- Hyperchloremia due to saline resuscitation
Tx of Metabolic Acidosis
- Consider giving _____ to help w/ immediate period until you’ve treated the underlying cause
- Allow for ______.
- Pts will be _____ in order to compensate, so avoid giving certain meds
- Sodium bicarbonate
- Respiratory compensation
- Hyperventilating, so don’t give meds which depress their resp drive
If urine chloride <25 = ____ responsive metabolic alkalosis
- 3 causes
- HCO3 >___
- Tx?**
<25
- GI losses
- Diuretics (contraction alkalosis)
- Cystic fibrosis
- Tx w/ FLUIDS!!
If urine chloride >25 = _____ responsive metabolic alkalosis
- 7 causes?
- Tx?
Non-chloride responsive metabolic alkalosis
- Barter’s syndrome
- Cushing’s
- Hyperaldosteronism
- K depletion
- Citrate toxicity for massive blood transfusion protocol
- Chronic diuretics
- Renin secreting tumor
- Tx underlying cause, may need potassium
Acidosis or Alkalosis?
- Hyper-ventilation
- Shift of oxy-hemoglobin dissociation curve
- Myocardial depression
- Sympathetic overactivityy (tachycardia, vasoconstriction, increased arrhythmias)
- Resistance to catecholamines
- Peripheral arteriolar vasodilation
Acidosis
Acidosis or Alkalosis?
- Peripheral venoconstriction
- Pulmonary artery constriction
- K shift out of cells (effect on myocytes)
- Cerebral vasodilation, increased ICP
- Central depression w/ high pCO2
Acidosis
Acidosis or Alkalosis?
- Decreased respiratory drive
- Shift of oxyhemoglobin curve (impaired O2 unloading)
- Depression of myocardial contractility
- Arrhythmias
- K shift into cells (hypokalemia)
- Cerebral vasoconstriction –> dec in cerebral blood flow
- Increased NM excitability
Alkalosis
Essentially not able to ventilate well enough, leading to an accumulation of CO2 (>45)
- 4 causes
Respiratory Acidosis
- Acute airway obstruction
- Lung disease
- CNS depression
- Neuromuscular disorder
Tx for Respiratory Acidosis
Excessive elimination of CO2 from lungs
“blowing off too much CO2”
- CO2 <__
- 4 sxs?
Respiratory Alkalosis
- CO2 <35
- Lightheadedness
- Palpitations
- Tachypnea
- +/- parasthesias
Most common cause of Respiratory Alkalosis?
Hyperventilation (anxiety is MC)
- Compensatory mechanism in sepsis
- Pain
- CNS (neurogenic hyperventilation)
- Salicylate overdose
- Pregnancy
- High altitude
- Hypoxemia
- Hepatic encephalopathy
Tx for Respiratory Alkalosis?
Tx underlying cause
T/F
- The body does not fully compensate for primary acid-base disorders
True
If pCO2 and HCO3 go in opposite directions, you likely have multiple disorders.
- Always focus on which value first in this case?
HCO3
Anytime you have a very high anion gap (AG>___), there automatically has to be ______, regardless of pH or serum bicarbonate concentration.
- AG>20
- primary metabolic acidosis
T/F
- The body generates a large anion gap to compensate for a primary disorder
False
The body DOES NOT generate a large anion gap to compensate for primary disorder
Mixed Acid-Base Disorders
- You can have up to ___ different disorders at a time
- You can have ___ & ____ at same time
- You can have only ONE ____ disorder
- What 2 things help you determine mixed disorders?
- Tx should always be directed at what?
- 3
- Metabolic alkalosis & Metabolic acidosis
- Respiratory disorder
- Anion & Delta gap calculations
- Cause of the primary disorder
Take home points
- A normal pH does not mean there is not an acid/base disorder
- Can have ____ acidosis & alkalosis at same time!
- _____ is usually pathologic (investigate!!)
- Metabolic
- Low bicarbonate
