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ABG Test 2
ABG
80
Nursing
Graduate
10/27/2012

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Cards

Term
At what pH will you become comatose?
Definition
pH = 7.0 and you will be comatose
Term
At what pH will you suffer from convulsions?
Definition
pH = 7.8 and you will have convulsions
Term
What happens to pH if PCOgoes up by 10mmHg?
Definition
pH ↓ 0.05 for every  ↑10mmHg PCO2
Term
What happens to pH if PCOdecreases by 10mmHg?
Definition
pH ↑0.1 for every ↓PCO2 by 10mmHg.
Term
What is normal O2 arterial content?
Definition
18-22 cc O2/100 ml of blood
Term
What are 4 causes of a normal anion gap ACIDOSIS?
Definition

BADR

B-icarb loss (GI/renal)

A-cid loads (amino acids)

D-ilution by non-bicarb solutions

R-enal deficits (impairment of H+ or NH4 secretions, hyperchloremia, bicarb loss

Term
What are 3 causes of increased gap acidosis?
Definition

LUK

L-actic acidosis

U-remia

K-etoacidosis (diabetic, alcohol, starvation)

Term
What is a normal lactate level?
Definition
0.5-1.5 mmol/L
Term
What is normal PvO2?
Definition
35-45 mmHg
Term
What is the formula for arterial oxygen content?
Definition
(1.34 x Hgb x O2sat) + (0.003 x PaO2)
Term
What is the A-a O2 gap?
Definition
It is the difference between AO2 and aO2.
Term
How do you calculate AO2?
Definition
AO2 = (FiO2 x (760-47)) - (PaCO2/0.8)
Term
How can you find out PaO2?
Definition
PaO2 is located on the ABG slip
Term
How do you determine a shunt?
Definition
(A-aO2 gap/20) = estimates your shunt
Term
What are 5 problems with bicarb administration?
Definition

1. Intraventricular hemorrhage

2. Hypernatremia

3. Hyperosmolarity

4. Left shift of oxyhemoglobin curve

5. Rebound alkalosis

Term
When do you give NaHCO3? (3)
Definition

1. pH 7.2 or lower

2. Resp. acidosis has been corrected.

3. Volume status corrected.

Term
What is the formula for bicarb administration and how do you manage it?
Definition

mEq HCO3 = (kg x BE x 0.2)

 

Give 1/2 calculated dose, then retest ABG

Term
What are 14 causes of alveolar hypoventilation?
Definition

1. CNS depression

2. Neuropathies

3. Sleep disorders

4. Airway obstruction

5. Increased dead space

6. Pulmonary embolus

7. Aspiration

8. Myopathies

9. Chest wall abnormalities

10. Obesity

11. Ventilator malfunction

12. Parenchymal lung dz

13. PNA

14. Interstitial lung dz

Term
What are 8 causes of increased CO2 production?
Definition

1. Large carb loads

2. Intense shivering

3. Thyroid storm

4. TPN

5. MH

6. Prolonged SZ

7. Burns

8. Fever

Term
What are 3 main causes of metabolic alkalosis?
Definition

1. Primary increase in plasma HCO3

2. Excess retention of bicarb or loss of H+ (diuretics - H+ secretion, increased aldosterone - H+ secretion, vomiting or gastric suction, severe hypokalemia and severe hypercalcemia)

3. Chronic steroid therapy (RA)

Term
What are 4 causes of metabolic acidosis?
Definition

1. Primary decrease in HCO3

2. Consumption of bicarb by a strong nonvolatile acid (gap)

3. Renal/GI wasting of bicarb (diarrhea)

4. Rapid dilution of ECF by a non-bicarb solution (no gap)

Term
_____ ______ ______ is one of the most critical factors in anesthesia for delivery of oxygen to the tissues.
Definition
Arterial oxygen content is one of the most critical factors in anesthesia for delivery of oxygen to the tissues.
Term
What are some poisons that can cause a gap acidosis? (4)
Definition

SEMP

S-alicylates (NSAIDs)

E-thylene glycol (antifreeze)

M-ethanol (paint thinner)

P-araldehyde (anticonvulsant)

Term
What are 12 problems with alkalosis?
Definition

1. Left shift of the oxyhemoglobin curve

2. Tissue hypoxia

3. Hypokalemia

4. Decreased ionized calcium

5. Circulatory depression

6. Coronary vasospasm

7. Neuromuscular irritability

8. Decreased cerebral blood flow

9. Increased SVR

10. Bronchoconstriction

11. Decreased PVR

12. Increased neuronal activity

9. 

Term
What happens to alkalosis under anesthesia (4)
Definition
  1. Prolonged opioid action due to increased protein binding
  2. Cerebral ischemia due to decreased blood flow
  3. Atria + ventricular dysrhythmia especially with hypokalemia
  4. Prolongation of NMB
Term
What is the definition of base excess?
Definition
Base excess - The amount of base required to titrate 1 liter of whole blood to a normal temp, normal pH, normal PaO2, and normal PaCO2.
Term
What is a base deficit good for?
Definition
Base deficit - The best way to determine if we're caught up on resuscitation and if patient is getting adequate perfusion. Lactate doesn't change for several hours, so base deficit will help in the OR.
Term
What does base deficit signal to the anesthetist? (6)
Definition

Base deficit signals

  1. Hypoxia
  2. Hypoperfusion
  3. Inability to utilize O
  4. Severity of shock
  5. O2 to tissues
  6. Adequacy of fluid resuscitation
Term
What is a normal BE?
Definition

-2 to 2

-2 to -5.5 (mild)

-6 to -14 (moderate)

<-14 (severe)

 

< -14 or doesn't correct in 24 hours is a strong indicator of MODS and mortality

Term
What is type 1 hypoxia?
Definition
Type 1 hypoxia is hypoxia alone, low to normal PaCO2
Term
What 6 examples of type 1 hypoxia?
Definition
  1. Atelectasis
  2. PNA
  3. PE
  4. Pleural effusion
  5. Hemo/Pneumothorax
  6. High altitude with low FiO2
Term
What is type 2 hypoxia?
Definition
Type 2 hypoxia is hypoxia with an increased ETCO2
Term
What are 7 causes of type 2 hypoxia?
Definition
  1. CNS depression
  2. High spinal cord lesion
  3. Phrenic nerve lesion
  4. Neuromuscular disorders
  5. Severe kyphoscoliosis
  6. COPD
  7. Advanced type 1 hypoxia, untreated
Term
What are 10 things that happen during acidosis?
Definition
  1. Myocardial + smooth muscle depression
  2. Reduced cardiac cotnractility
  3. Reduced SVR
  4. Increased PVR
  5. Severe tissue hypoxia
  6. Less responsive to pressors/catecholamines
  7. Decreased threshold for v-fib
  8. Progressive hyperkalemia -> cells give up Ca++
  9. CNS depression (from CO2 narcosis)
  10. Decreased neuronal activity
Term
What are 4 things acidosis causes under anesthesia?
Definition
  1. Potentiation of depressant effects of anesthesia to CNS and circulation
  2. Decreased airway reflexes
  3. Changes the fraction of drugs to non-ionized form
  4. Resp. acidosis augments NMBs
Term
What PaO2 signals hypoxia at FiO2 40%
Definition
PaO2 <70% at FiO2 40% indicates hypoxia and need for intubation
Term
What causes the oxyhemoglobin curve to shift to the left? (4)  What happens to oxygen affinity?
Definition
  1. Hypothermia
  2. Hypocarbia
  3. Alkalosis
  4. Decreased 2-3 DPG

Oxygen affinity increases. Oxygen picks up easier in the lungs, but is harder to release at the tissues.

Term
What causes the oxyhemoglobin curve to shift to the right? (4)  What happens to oxygen affinity?
Definition
  1. Hyperthermia
  2. Hypercarbia
  3. Acidosis
  4. Increased 2-3 DPG

Oxygen affinity decreases. Easier to unload oxygen at the cells, but more difficult to pick up at the lungs.

Term
List 7 indications for intubation.
Definition
  1. RR >35
  2. VC <15cc/kg adult  <10cc/kg child
  3. Negative insp. force <20
  4. PaO2 <70mmHg on FiO2 40%
  5. A-aO2 gradient >350 mmHg on FiO2 100%
  6. PaCO2 >55
  7. Vd/Vt >0.6
Term
How low can intracellular pH become?
Definition
Intracellular pH can be as low as 6.0, because metabolism occurs here.
Term
What is the survivable pH range?
Definition
pH >7.0 to <7.8
Term
What is the pH range of urine?
Definition
Urine pH is 4.8 - 8.0; urine buffers the body by a wide range.
Term
Respiratory centers can handle _____ as much _____ as the chemical acid-base buffer systems; it is _______.
Definition
Respiratory centers can handle twice as much acid as the chemical acid-base buffer systems; it is slower.
Term

True/False

 

The chemical acid-base buffers fixes the problem by soaking up the acid or bicarb.

Definition

False

 

The chemical acid-base buffers do NOT fix the problem, they just soak up the acid or bicarb while waiting for something better.

Term
Respiratory buffers are complete/incomplete. They start to buffer in __ - __ minutes. Steady state is achieved in __ - __ hours.
Definition
Respiratory buffers are incomplete. They start to buffer in 3 - 12 minutes. Steady state is achieved in 12 - 24 hours.
Term
What are the limits of the respiratory buffer system?
Definition
The respiratory buffer system will not allow you to become hypercarbic or hypocarbic. If you have too much COyou may end up with perfusion problems.
Term
The kidneys can get rid of more ____ but it takes ____.
Definition
The kidneys can get rid of more acid but it takes some time.
Term
Renal buffering is measurable within __ - __ _____, and it reaches maximum buffering in __ ____.
Definition

Renal buffering is measurable within 12 - 24 hours, and it reaches maximum buffering in

days.

Term
What is an  example of extracellular buffers?
Definition
H2CO3/HCO3-
Term
What are three examples of intracellular buffers? Which one takes the longest to buffer and how long does it take?
Definition
  1. Hemoglobin: Hgb/Hb
  2. Proteins: PrH/Pr
  3. Bone is a buffer: Soaks up H+ and gives up Ca++. Anyone with chronic acidosis will have brittle bones.

Protein and bones buffer within 2-4 hours.

Term
What are two urinary buffers? What does urine create?
Definition

Phosphates: H2PO4/HPO4

Ammonia: NH3/NH4

Urine creates more acids or more CO2

Term

True/False

 

Plasma bicarb is immediate, but it cannot fully compensate for respiratory acidosis.

Definition
True
Term
Interstitial buffering occurs within ____ _____
Definition
Interstitial buffering occurs within 15-20 minutes.
Term
Proteins and bone buffering occurs within _-_ ____.
Definition
Proteins and bone buffering occurs within 2-4 hours.
Term

True/False

Changes in PaO2 stimulates baroreceptors in the brain (medulla) and carotid bodies.

Definition

False

Changes in PaO2 stimulates chemoreceptors in the brain (medulla) and carotid bodies.

Term
Does the H+ or CO2+ stimulate changes in pH?
Definition
The H+ does.
Term
Describe the kidneys and bicarb in compensating for acidosis/alkalosis.
Definition
Bicarb ions are constantly filtered and reabsorbed. Bicarb has to join with another H ion in order for it to be lipid soluble/non-ionized to be reabsorbed. If the patient is alkalotic, there is not enough H ions around, the bicarb will be excreted. If the patient is acidotic, there are many H ions around, this drives the change from glutamate to ammonia and we get more bicarb.
Term

True/False

Renal compensation is considered the most powerful and the slowest.

Definition
True
Term
How much arterial oxygen content does the heart need?
Definition
The heart extracts at LEAST 14 ml O2/100 ml of blood. It has a high oxygen extraction ratio.
Term

What is a normal A-aDO2?

 

Definition
10-20 mmHg (1/4 patient's age)
Term
What is the formula to calculate a patient's estimated PaO2?
Definition
PaO2 = 102 - (age/3)
Term
What is the half-life of lactate?
Definition
Lactate half-life is 3 hours.
Term
What changes SvO2?
Definition

Changes in SvO2 (COAL)

  1. C-ardiac output -> is O2 circulating?
  2. O-xygen consumption -> tissues using O2?
  3. A-rterial O2 content -> do we have enough Hgb?
  4. L-oading of Hgb (SaO2) - Hgb loaded with O2?
Term
What is the oxygen extraction ratio?
Definition

[(CaO2-CvO2)/CaO2] = 25%

We only use 25% of the oxygen circulating in our body.

 

This gives us an oxygen reserve.

Term
How long is an ABG sample good for by itself? What if it's on ice/slush?
Definition

ABG sample alone - 15 minutes

ABG sample in slush - 60 minutes

Term
How long to wait to evaluate vent changes with an ABG?
Definition

Wait 5 minutes for healthy lungs

Wait 30 minutes for diseased lungs.

Term
Formula for oxygen consumption and its units?
Definition

Kg x 103/4

 

70 kg = 242 ml/min

Term
Formula for CO2 consumption and its units?
Definition

kg x 83/4

 

70 kg = 194 ml/min

Term
1 kpa = ___ mmHg
Definition
1 kpa = 7.5 mmHg
Term
ACO2 is normally __ mmHg or ___%
Definition
ACO2 is normally 40 mmHg or 5.6%
Term

True/False

We must calculate the A-a gradient because we cannot estimate how much oxygen is in the alveoli with end-tidal oxygen concentrations.

Definition
True
Term
A-aDO2/20 estimates what?
Definition

Estimates a shunt.

 

Term
What is the most common cause of hypoxia under anesthesia?
Definition
A shunt
Term
What is the formula for alveolar ventilation?
Definition
Alveolar ventilation = minute ventilation - dead space
Term
What is a normal amount of dead space? What doe GETA do to dead space?
Definition

Normal dead space = 1 ml/kg

GETA doubles dead space.

Term

True/False

Dead space is zone 2 and decreases while under anesthesia.

Definition

False

Dead space is zone 1 and increases while under anesthesia.

Term

True/False

Dead space changes ETCO2 and arterial content, not SpO2.

Definition
True
Term

True/False

If we have hypoventilation, we will have an increased ETCO2 because of a buildup of CO2.

Definition

False

If we have hypoventilation, we will have a decreased ETCO2, and that is because most of the exhaled breath is dead space (diluted) even though arterial CO2 is rising.

Term
DLO2 = ??
Definition

DLO= Oxygen diffusing capacity.

21ml/min/mmHg diffusion gradient

Fluid in the lungs changes diffusion of oxygen. We don't measure diffusion with oxygen, we measure it with carbon monoxide.

Term
DLO2 <600 = ??
Definition
Indicates sepsis and MODS
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