ventilators

Question 1

why we need ventilators

Answer 1

• Inability of the lungs to keep up with the body’s needs
• Airway compromise (Trauma, burns, fractures, etc)
• Stridor
• Loss of respiratory drive (Strokes, brain injury, intoxicants)
• Treatment for increased intracranial pressure: (To induce hyperventilation to lower intracranial pressure)
• Inability to ventilate properly
• Inability to oxygenate appropriately

Question 2

noninvasive ventilation

Answer 2

Nasal cannula (in L)
Venturi mask (variable valves for 24-50% fiO2)
Nonrebreather (100%/15L)
High flow nasal cannula (can vary both the rate and the Fio2 up to 100%)
CPAP PAP/FIO2)
BIPAP (IPAP/EPAP/Fio2) The only true noninvasive VENTILATION

Question 3

invasive ventilation

Answer 3

Endotracheal Intubation:
Assist Control- volume controlled versus pressure controlled
Synchronized Intermittent Mechanical Ventilation
Pressure Support
Many others!

Question 4

oxygenation

Answer 4

use lowest value of oxygenation to maintain art. hemoglobin sat of 90% or more (PO2 of 60mmHg)

• higher levels have no proven benefit and may cause free radical damage
• restoration of normoxia may cause HYPOventilation in chronic hypercapnic pts (high CO2) -(lose drive to breathe (low O2))

Question 5

noninvasive positive pressure ventilation

Answer 5

• Bilevel positive pressure ventilation (BIPAP) vs. Continuous positive pressure ventilation (CPAP)
• Full face mask, nasal mask, nasal pillows can all be used

Question 6

noninvasive positive pressure ventilation: first in line for

Answer 6

pts with hypercapneic respiratory failure who can protect their away, handle their secretions and tolerate the mask (reduces need for intubation)

Question 7

for chronic resp. failure, this tx is tried and can easily be used at home for OSA, obesity hypo vent.

Answer 7

CPAP

for advanced disease if a patient fails CPAP they may be transitioned to nocturnal home BIPAP

Question 8

for acute resp. failure in hospital, this is preferred

Answer 8

BIPAP

Question 9

invasive ventilation: tracheal intubation indications

Answer 9

Hypoxemia despite supplemental oxygen
Upper airway obstruction (stridor)
Impaired airway protection (trauma)
Inability to clear secretions (relative)
Severe respiratory acidosis
Progressive general fatigue, tachypnea, use of accessory muscles, or mental deterioration
Apnea

Question 10

Continuous mechanical ventilation (assist control)

Answer 10

Can be volume controlled or pressure controlled (typically use volume control)
factors set:
-Fio2 (percentage of oxygen delivered)
-Respiratory rate
-Positive end expiratory pressure
-Tidal Volume (in Volume control) vs Peak Pressure (In Pressure control)

Question 11

in acute resp. failure, begin with

Answer 11

100% Fio2 and quickly taper down to lowest level possible to maintain saturations

Question 12

RR may inc. from (12) in these pts

Answer 12

hypercapneic, to blow of CO2 and red. acidosis

Question 13

tidal volume is calculate based off

Answer 13

ideal body weight

Typically aim for 6-8mL/Kg of IBW (which is calculated based on sex and height)

Question 14

Higher tidal volumes may also allow for blowing off of CO2 but be careful, too high TV may result in

Answer 14

barotrauma

Question 15

any given TB will cause lungs to reach certain pk pressure (compliance), aim to keep pressures…

Answer 15

LOW:

Question 16

PEEP, why necessary?

Answer 16

positive end expiratory pressure (relationship btw TV and pk pressure)
need to prevent atelectasis!
typically PEEP = 5

Question 17

theses pts may need higher PEEP to maintain oxygenation

Answer 17

ARDS pts

Question 18

PEEP causes inc. pressure during exhalation, can cause

Answer 18

cardiopulmonary changes (elevated intrathoracic pressure causing decreased systemic venous return) leading to decreased cardiac output and hypotension
*turn PEEP to 0 during acute hemodynamic compromise

Question 19

PEEP also increases risk for

Answer 19

tension pneumothorax in pt with known PTX

temp. turn off PEEP til definitive tx given

Question 20

example volume control settings

Answer 20

rate of 12/Fio2 of 35%/ TV of 450 and PEEP pf 5

-pt. breathes over vent. @ rate of 18, for the 6 additional breaths the pt. still receives set TV, FiO2, and PEEP

Question 21

difference btw volume and pressure control

Answer 21

• in volume control you set a TV and based on lung compliance the lungs produce a certain peak pressure
• In pressure control you set the peak pressure and based on the lung compliance the lungs produce a certain volume
• otherwise identical

Question 22

problem with pressure control

Answer 22

it doesn’t give a set TV and therefore if not watching closely might have small tidal volumes leading to hypercapnea

Question 23

pressure support

Answer 23

pt. drives the breath, no set TV/rate
Besides for given Fio2 and PEEP the clinician choses a preset “pressure support” which is additional continuous pressure given to aid in overcoming resistance from endotracheal tube making it easier for patient to breath (gives additional support on top of pk)
-considered “weaning” mode (can pt. handle extubation?), CPAP, spontaneous breathing trial

Question 24

Synchronized Intermittent Mechanical Ventilation (SIMV)

Answer 24

combination of both Volume Control AC and Pressure support

-previously “weaning” mode, now not as much, used by some surgeons, anesthesiologists, avoided in ICU pts

Question 25

example of SIMV

Answer 25

This time if patient is overbreathing at a rate of 18 instead of receiving the set TV and for those additional 6 breaths, those 6 breaths are only given a predetermined additional pressure support
Therefore those 6 breaths are completely patient driven and only have some additional CPAP to reduce patient effort

Question 26

if endotracheal tube is positioned poorly

Answer 26

may cause atelectasis of contralateral lung with hyperinflation of intubated lung
(aim to be 2-3cm above carina)

Question 27

other complications of mech. ventilation

Answer 27

• Barotrauma from high transmural pressure can cause subcutaneous emphysema, pneumothorax, or gas embolism
• Volutrauma from overdistension of alveoli from excessive tidal volumes tends to cause inflammatory changes
• Ventilator associated pneumonias (VAP)