1
Q
ABGs are frequently used to detect and monitor indices of what 3 things?
A
- Oxygenation
- Ventilation
- Acid-base balance
2
Q
ABGs quantify levels of _____ & ______.
A
- carboxyhemoglobin
- methemoglobin
3
Q
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 _____.
A
- Radial
- Brachial or femoral aa
- anticoagulant (heparin)
- 5 - 15 mins
4
Q
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?
A
- How well pt is oxygenating
- NOT: acid base conditions
- pO2 from ABG is more reliable than pulse ox.
5
Q
- Body maintains precise control of ____ to maintain homeostasis
- ____ are used to keep pH in narrow range.
A
- Hydrogen ions
- Buffer systems
6
Q
- Acidemia is pH <____
- Alkalemia is pH >____
A
- <7.35
- >7.45
7
Q
pH of blood
A
Acidemia & Alkalemia
8
Q
Acid/Base Disorder
A
Acidosis & Alkalosis
9
Q
Tx for acid/base disturbances?
A
Management of underlying disease
(can have up to 3 disorders)
10
Q
- 2 types of compensation for acid/base disorders?
- Which one is rapid and which is slow?
A
- Respiratory compensation (rapid)
- Metabolic compensation (days - weeks)
11
Q
Acid/Base
- A primary respiratory problem involves ___
- If greater than ___ is acidosis
- If less than ____ is alkalosis
A
- pCO2
- >45 = acidosis
- <35 = alkalosis
12
Q
Acid/Base
- Primary metabolic problem involves ____.
- If greater than ___ is alkalosis
- If less than ____ is acidosis
A
13
Q
- pH: >7.45
- Disturbance: decreased pCO2 (<35)
- Secondary response: decreased HCO3
A
Respiratory Alkalosis
14
Q
- pH: >7.45
- Disturbance: increased HCO3 (>26)
- Secondary response: increased pCO2
A
Metabolic Alkalosis
15
Q
- pH: <7.35
- Disturbance: increased pCO2 (>45)
- Secondary response: increased HCO3
A
Respiratory acidosis
16
Q
- pH: <7.35
- Disturbance: decreased HCO3 (<22)
- Secondary response: decreased pCO2
A
Metabolic acidosis
17
Q
If both pCO2 and HCO3 are HIGH, what could it be?
A
- Respiratory acidosis
- Metabolic alkalosis
18
Q
If both pCO2 and HCO3 are LOW, what could it be?
A
- Respiratory alkalosis
- Metabolic acidosis
19
Q
If pCO2 and HCO3 are moving in opposite directions, there is what?
A
Mixed disorder is present
20
Q
What causes high anion gap metabolic acidosis?
A
- Methanol
- Uremia
- DKA
Propylene glycol - Iron/Isoniazid
- Lactate
- Ethanol/ethylene glycol
- Salicylates/starvation
(MUDPILES)
21
Q
Causes of non-anion gap metabolic acidosis
A
- GI bicarbonate loss
- Renal bicarbonate losses
- Hyperchloremia due to saline resuscitation
22
Q
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
A
- Sodium bicarbonate
- Respiratory compensation
- Hyperventilating, so don’t give meds which depress their resp drive
23
Q
If urine chloride <25 = ____ responsive metabolic alkalosis
- 3 causes
- HCO3 >___
- Tx?**
A
<25
- GI losses
- Diuretics (contraction alkalosis)
- Cystic fibrosis
- Tx w/ FLUIDS!!
24
Q
If urine chloride >25 = _____ responsive metabolic alkalosis
- 7 causes?
- Tx?
A
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
25
**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
26
**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
27
**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
28
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
29
Tx for Respiratory Acidosis
30
Excessive elimination of CO2 from lungs
"blowing off too much CO2"
* CO2 \<\_\_
* 4 sxs?
**Respiratory Alkalosis**
* CO2 \<35
* Lightheadedness
* Palpitations
* Tachypnea
* +/- parasthesias
31
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
32
Tx for Respiratory Alkalosis?
Tx underlying cause
33
**T/F**
* The body does not fully compensate for primary acid-base disorders
True
34
If pCO2 and HCO3 go in opposite directions, you likely have multiple disorders.
* Always focus on which value first in this case?
HCO3
35
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
36
**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
37
**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
38
**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
SG F2 E5
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