Mechanical Ventilation

Question 1

Rapid Shallow Breathing Index (RSBI)

Answer 1

Respiratory Rate / Tidal Volume ( in L)

Question 2

Pulmonary mechanic desired for extubation (6)

Answer 2

1. RSBI < 105
2. Negative inspiratory force > -20
3. Vital Capacity > 15 mL/kg
4. • cuff leak
5. Change in RSBI during 2 hour SBT < 20%, 30 min SBT < 5%
6. Reason for intubation resolved (mental status, secretions)

Question 3

Vital Capacity

Answer 3

Inspiratory reserve volume + tidal volume + expiratory reserve volume

Question 4

ARDS three Classifications and PaO2/FiO2 ratio

Answer 4

1. MIld: 200-300 (PEEP > 5)
2. Moderate: 100-200 (PEEP > 5)
3. Severe: < 100 (PEEP > 5)

Question 5

Mortality and median duration of mechanical ventilation for

1. Mild ARDS
2. Moderate ARDS
3. Severe ARDS

Answer 5

1. Mild ARDS: 27% and 5 days
2. Moderate ARDS: 32% and 7 days
3. Severe ARDS: 45% and 9 days

Question 6

Respiratory Equation of Motion

Answer 6

Pmus + Pvent = F x R + TV/C

Question 7

Transairway pressure

Answer 7

Pressure at mouth opening - alveolar pressure

Question 8

Transthoracic pressure

Answer 8

Alveolar pressure - body surface pressure

Question 9

Transpulmonary pressure

Answer 9

alveolar pressure - pleural pressure

Question 10

Transrespiratory pressure

Answer 10

Pressure at airway opening - body surface pressure

Question 11

Compliance

Answer 11

Change in volume / change in pressure (normal > 100 ml / cm H2O)

Question 12

Dynamic Compliance

Answer 12

tidal volume / PIP - PEEP

Question 13

Static compliance

Answer 13

Tidal volume / Pplateau - PEEP

Question 14

Resistance

Answer 14

pressure / flow = PIP - Pplateau / flow

Question 15

Work

Question 16

Four phases of mechanical ventilation

Answer 16

1. Expiratory phase
2. Triggering
3. Inspiratory phase
4. Cycling

Question 17

ventilation pressure

Answer 17

Resistive pressure x

Question 18

Time constant

Answer 18

Compliance x resistance

Question 19

Three ventilator variables that determine the breath

Answer 19

1. Trigger variable
2. Target or limit variable
3. Cycle variable

Question 20

Three variables that can increase risk of instrinsic PEEP

Answer 20

1. Minute ventilation increases
2. Expiratory time fraction decreases
3. Time constant (compliance x resistance) increases

Question 21

Way to quantify intrinsic PEEP

Answer 21

Expiratory hold will allow intrinsic PEEP to equilibrate and be quantified.