test 9

Question 1

Our continued health depends on the body’s

ability

Answer 1

• To deliver the appropriate amount of oxygen to
each cell
• For each cell to uptake and consume the proper
amount of oxygen

Question 2

Normal Oxygen Consumption

Answer 2

200-250 mL O2/min

Question 3

What is the final common

pathway of all causes of death

Answer 3

tissue hypoxia

Question 4

energy production is determined by what

Answer 4

metabolic rate

Question 5

creation of energy is supported by what

Answer 5

adequate amounts of glucose and oxygen delivered to the cells

Question 6

similarities between aerobic and anaerobic metabolism

Answer 6

• both start with glucose metabolized to pyruvate

- both produce ATP

Question 7

Aerobic metabolism

Answer 7

-O2 present
• Pyruvate converted to acetyl-CoA, which enters the Krebs cycle
which produces carbon dioxide, water and ATP
• 1 mole glucose→ 36 moles ATP
-end product= CO2 and H2O

Question 8

Anaerobic metabolism

Answer 8

• Pyruvate converted to lactic acid and ATP
• 1 mole glucose→ 2 moles ATP
-end product= lactic acid

Question 9

monitoring what can tell you a lot about what has occurred during your pump run

Answer 9

lactate

Question 10

why measure lactic acid in blood

Answer 10

-if lactic acid present, we know that there are areas in our body where anaerobic metabolism has occurred

Question 11

Arterial O2 content

Answer 11

17-20 mL/100mL blood

Question 12

Venous O2 content

Answer 12

12-15 mL/100mL blood

Question 13

A-V O2 difference

Answer 13

4-6 mL/100mL blood

Question 14

what is one of the best ways to increase O2 content

Answer 14

-increase hemaglobin

Question 15

O2 delivery (& normal value)

Answer 15

• DO2 = Arterial content × Cardiac output
• 950-1150 mL O2/min
• Indexed: 550-650 mL O2/min/m2

Question 16

O2 reserve

Answer 16

• The amount of oxygen left AFTER consumption
has taken place
• Venous gases returning to the heart
• A built-in physiologic buffer (in case we need it)

Question 17

Normal Oxygen Reserve

Answer 17

• 700-800 mL O2/min

- Indexed: 450 mL O2/min/m2

Question 18

How long can you use your reserve

Answer 18

• around 32% SvO2

- then anaerobic metabolism starts to come into play

Question 19

Factors That Increase Oxygen Consumption

Answer 19

• Patient conditions
• Medications
• Procedures

Question 20

Patient Conditions that Increase Oxygen Consumption

Answer 20

• Minor surgery: 7% increase
• Fever (each 1 o C): 10%
• Agitation: 16%
• Increased work of breathing: 40%
• Severe infection: 60%
• Chest trauma: 60%
• Shivering: 50 to 100%
• Sepsis: 50 to 100%

Question 21

Medications that Increase Oxygen Consumption

Answer 21

• sympathetic agonists

- causing an increase in CO and vasoconstriction

Question 22

Procedures that Increase Oxygen Consumption

Answer 22

• Dressing change: 10% increase
• Physical examination: 20%
• Visitors: 22%
• Endotracheal suctioning: 27%
• Turning: 31%
• Chest physiotherapy: 35%
• Nasal intubation: 25 to 40%

Question 23

Factors that Decrease Oxygen Consumption

Answer 23

• Hypothermia (7oC): 50% decrease
• Morphine sulfate IV: 21%
• Anesthesia: 25%
• Assist/control ventilation: 30%
• Neuromuscular blocking agents

Question 24

Ischemic hypoxia

Answer 24

• Inadequate blood flow (regional or general)
• Obstructive lesions of blood vessels
-(Coronary or cerebral thrombosis or spasm or Peripheral vascular disease)

Question 25

Hypoxemic hypoxia

Answer 25

- Inadequate transfer of oxygen from the lungs to the hemoglobin molecule - Hypoxemia most common cause, Carbon monoxide poisoning, Methemoglobinemia

Question 26

Anemic hypoxia

Answer 26

-Deficiency of hemoglobin molecules

Question 27

Toxic hypoxia

Answer 27

- Inability of body cells to uptake or use oxygen | - Sepsis, cyanide toxicity, and ethanol toxicity

Question 28

Excessive tissue requirements

Answer 28

- Oxygen demand higher than system can supply | - Hypermetabolism, Sepsis, alcohol withdrawal, extreme fever

Question 29

Impaired oxygen unloading

Answer 29

- At the capillary level | - alkalemia, hypocarbia, and Administration of large amounts of banked blood

Question 30

Compensatory Mechanisms for Impaired Tissue Oxygenation

Answer 30

1. Increase cardiac output (primary response) 2. Draw from venous reserve 3. Polycythemia

Question 31

Increase cardiac output (primary response)

Answer 31

• The tissues control the cardiac output in accordance with their need for oxygen • Healthy heart can increase to 15-25 L/min -acute response

Question 32

Draw from venous reserve

Answer 32

• Extract more oxygen from hemoglobin • Can decrease venous sat to 32% before anaerobic metabolism starts -acute response

Question 33

Polycythemia

Answer 33

• Increase amount of hemoglobin and RBC mass • Takes weeks to develop -long term response

Question 34

Monitoring Oxygen Transport

Answer 34

* Arterial and mixed venous blood gas (central lab) * Point-of-care blood gas * Noninvasive pulse oximetry * Invasive mixed venous saturation * Continuous indwelling arterial blood gas * Transcutaneous measurement of local tissue saturation

Question 35

Arterial and Mixed Venous Blood Gases from Central Lab

Answer 35

* Lag time between sampling and results * Intermittently performed * May not detect acute, severe hypoxemia

Question 36

Point-of-Care Blood Gas Analyzers

Answer 36

-bedside blood gas

Question 37

Point-of-Care Blood Gas Analyzers pros

Answer 37

``` • Able to measure gases, electrolytes, glucose, lactate, urea, nitrogen and hematocrit • Small and portable • Small blood volume required • Self-calibrating • Disposable cartridges ```

Question 38

Point-of-Care Blood Gas Analyzers cons

Answer 38

• Can be expensive with labor intensive quality control

Question 39

Noninvasive Pulse Oximetry

Answer 39

• 2 light emitting diodes (LED) send red and infrared light through the arterial vascular bed • Photodetector measures transmitted light and detects the relative amount of color absorbed by arterial blood and estimates the saturation • Saturated Hb= Absorbs more infrared light • Desaturated Hb= Absorbs more red light -can be placed on the patient’s finger, toe, earlobe or nose bridge • Accuracy: ± 4% • less reliable with saturations between 50 and 70% • no accuracy below 50% • Adequate peripheral perfusion required

Question 40

Noninvasive pulse oximetry does NOT

Answer 40

-guarantee that oxygen is being delivered to or used by the cells

Question 41

Falsely ↓ Saturation Values for Pulse Oximetry

Answer 41

* Nail polish/acrylic nails * Dark skin pigmentation * IV dyes * Lipid infusions * Anemia (Hct < 10%) * Venous pulses * Patient movement

Question 42

Falsely ↑ Saturation Values Pulse Oximetry

Answer 42

* Elevated carboxyhemoglobin * Elevated methemoglobin * Intense surgical light

Question 43

SpO2 Ranges

Answer 43

* 96-99% : Normal * 85-90% : Mild tissue hypoxia * 75-85% : Significant widespread tissue hypoxia

Question 44

Invasive Mixed Venous Saturation

Answer 44

• Measured via fiberoptic pulmonary artery catheter • Uses reflectance spectrophotometry

Question 45

Invasive Mixed Venous Saturation: General Info

Answer 45

• very fragile so you don't want to break them or bend/kink • Manufacturer specific pre-insertion calibration required and in vivo calibration • Keep catheter tip away from the wall of the pulmonary artery (reflection from the vessel will distort results) • Not able to distinguish carboxyhemoglobin and methemoglobin from oxyhemoglobin

Question 46

Continuous Indwelling Arterial and Venous Gases

Answer 46

- can measure saturation through tubing of pump - can take continuous blood gasses of samples - calibrate with tanks of gas

Question 47

Transcutaneous Measurement of Local Tissue Saturation

Answer 47

- near-infrared spectrometry (NIRS) • Uses specific, calibrated wavelengths of nearinfrared light • light is absorbed relative to amount of oxygen attached to the hemoglobin in the blood vessels