Oxygen and Ventilator Management Lecture Powerpoint

Question 1

Acute respiratory failure

Answer 1

Inability of respiratory system to meet oxygenation, ventilation, or metabolic requirements of the patient, either hypoxemic (PaO2<50mmHg), hypercapnic (PaCO2>50mmHg), or mixed

Question 2

Hypercapnia

Answer 2

Elevated CO2 levels in the blood, unable to be compensated with minute ventilation (increased physiologic dead space)

Question 3

Components of the respiratory system include many things beyond the lungs including… (5)

Answer 3

• CNS
• PNS
• Neuromuscular system
• Thorax and pleura
• Cardiovascular system

Question 4

5 pathophysiological mechanisms of hypoxemic respiratory failure

Answer 4

• V/Q mismatch
• Shunt
• Hypoventilation
• Diffusion abnormalities
• Decreased FiO2

Question 5

Normal A-a gradient and what it means, what does an elevated one mean?

Answer 5

10-20mmHg, if normal then hypoventilation is source of hypoxemic respiratory failure, increased in V/Q mismatch and shunt

Question 6

Normal V/Q ratio, what does an elevated and decreased one mean?

Answer 6

Between .8-1, increased ratio indicates dead space ventilation, decreased indicates intrapulmonary shunt

Question 7

Having blood but no air indicates what about V/Q ratio?

Answer 7

Decreased V/Q ratio

Question 8

Having air but no blood indicates what about V/Q ratio?

Answer 8

Increased V/Q ratio

Question 9

What can cause increase in physiologic dead space? (3)

Answer 9

Emphysema, COPD, or asthma exacerbation

Question 10

What can cause mixed venous with arterial blood (5)

Answer 10

ASD/VSD, pulmonary edema, atelectasis, pneumonia, pneumothorax

Question 11

Shunt fraction

Answer 11

Fraction of cardiac output that represents intrapulmonary shunt (perfused but not ventilated space)

Question 12

3 measures to determine hypoxic respiratory failure

Answer 12

• A-a gradient
• Mixed or central venous PO2
• Inspiratory pressure

Question 13

In all situations except a shunt we see a response to increased FiO2 causing ____ to rise

Answer 13

PaO2

Question 14

Signs and symptoms of acute respiratory failure (5)

Answer 14

• Altered mental status
• Increased work of breathing
• Bradypnea
• Cyanosis
• Diaphoresis

Question 15

Modes of oxygenation and ventilation (6)

Answer 15

• Nasal cannula (should not go above 6L which is FiO2 44%)
• Non-rebreather (used in emergency delivery)
• High flow nasal cannula (used for hypoxia)
• Bag valve mask device (Emergency settings, squeezed bag with one way valve, has to be hooked up to oxygen)
• CPAP (continuous airflow creating positive pressure to stent open airways, used in sleep apnea)
• Bipap/NIPPV - IPAP/EPAP (ratio must be maintained if increasing, provides positive pressure without intubation)

Question 16

Who benefits from NIPPV/Bipap (4)

Answer 16

• acute exacerbations of COPD
• Alert and cooperative patients
• Increased work of breathing
• sleep apnea

Question 17

Contraindications to NIPPV/Bipap (5)

Answer 17

• Cardiac or respiratory arrest
• Aspiration risk
• Facial trauma
• Hemodynamic instability
• Inevitable intubation

Question 18

How to decide when to intubate a patient (3)

Answer 18

• When there is failure of airway maintenance or protection
• Failure to achieve desired goals with current respiratory support
• Illness expected to worsen

Question 19

Low PaO2 below 60% is at high risk for sudden ____ because of the ____

Answer 19

desaturation, oxyhemoglobin dissociation curve

Question 20

Indications for mechanical ventilation (intubation) (4)

Answer 20

• Failure of NIPPV
• Loss of ventilatory drive
• Chest trauma
• Unstable mental status

Question 21

Intubation procedure steps (8)

Answer 21

• Preoxygenation
• Sedative and paralytic administration
• visualize tubes passing thru cords
• listen for breath sounds bilaterally but no sounds over stomach
• condensation in tube should accumulate
• End tidal CO2 strip inserted should change blue to yellow
• Get CXR
• Chest should rise

Question 22

Potential issues with initiation of mechanical ventilation (3)

Answer 22

• Increased intrathoracic pressure and decreased venous return/cardiac output
• Orolaryngeal damage
• Nosocomial infection after prolonged intubation

Question 23

Ventilator settings (4)

Answer 23

Tidal volume: set corresponding to ideal body weight 6-8cc/kg
Respiratory rate: usually 16-18
FiO2: starts at 100% and then weaned to 40%
PEEP (positive end expiratory pressure): Generally started at 5mmHg (don’t want to overdistend for fear of pneumo)

Question 24

Assist control ventilator vs pressure support

Answer 24

Assist control is either volume controlled (patient gets same volume with every breath, but can initiate more breaths but will always get that tidal volume) or pressure controlled (inspiratory pressure is set for every breath taken, but get to pick tidal volume which is more comfortable for patient to allow to take bigger breaths) but in both scenarios rate of respiration is automated but can be controlled by patient. While pressure support is a pressure assisted but patient determines rate of breath and tidal volume, requiring only setting a PEEP and pressure above a PEEP similar to a Bipap, has backup apnea alarms and is often used as a weaning mode before removing intubation

Question 25

SIMV ventilation

Answer 25

Hybrid of assist control and pressure support, ventilator delivered breaths with tidal volume and respiratory rate set, and every breath taken gets those, but if they initiate their own breath get their own tidal volume they want

Question 26

Mechanical ventilation adverse effects (2)

Answer 26

• Volutrauma such as pneumothorax

- Hemodynamic compromise

Question 27

Peak airway pressure

Answer 27

Sum of pressure required to overcome airway resistance and pressure required to overcome elastic properties of the lung and chest wall

Question 28

Plateau pressure

Answer 28

Pressure required to overcome elastic recoil within the lung and chest wall

Question 29

How can we determine that the etiology of hypoxemia is due to intrapulmonary shunt?

Answer 29

By administering 100% FiO2 for 15 min, we should see an increase in PaO2 indicating that we have a V/Q mismatch or minor shunt, but if PaO2 doesn’t increase this is a severe intrapulmonary shunt

Question 30

Auto-PEEP

Answer 30

Occurrs when expiratory time is too short for full exhalation when on ventilator resulting in lung hyperinflation, fixed by either performing expiratory hold maneuver or decreasing RR or tidal volume