ARDS & Oxygenation Flashcards
What does ARDS stand for?
Acute respiratory distress syndrome
Definition of ARDS?
Respiratory failure second to pulmonary or systemic insult without evidence of heart failure
Onset of ARDS?
Generally 12-48hrs but up to 1 wk of trigger
Causes of ARDS?
MC: Sepsis, aspiration/inhalation of harmful substances, burns, trauma, pneumonia, intubation
Other: OD, high altitude sickness, multiple transfusions, DIC, pancreatitis
Pathophys of ARDS?
Damage to capillary and alveolar endothelial cells d/t increased vascular permeability and diminished surfactant —> pulmonary edema & alveolar collapse causing hypoxemia
Characteristics of ARDS?
Rapid onset dyspnea (tachypnea, retractions), crackles, abnormal CXR, hypoxemia refractory to O2, shock can develop
CXR for ARDS?
Diffuse bilateral patchy infiltrates (air bronchograms)
-venus congestion, cardiomegaly, pleural effusion uncommon
Treatment for ARDS?
aggressive dx & tx of underlying disorder, usually intubation needed/adjustments to ventilator to avoid O2 toxicities
-supportive tx: fluids, fever control
Are there any preventative measures for ARDS?
None identified
Is steroid therapy effective for ARDS?
Not proven
Mortality rate of ARDS?
30-40% (90% if secondary to sepsis)
If ARDS patients survive, they will have some degree of _______ _________
chronic symptoms
What is a cricothyrotomy?
Emergency surgical airway (incision made between thyroid cartilage and cricoid cartilage)
Indications for a cricothyrotomy?
Unable to intubate or maintain oxygenation w/ bagging, severe facial trauma
Relative C/I of cricothyrotomy?
<12 y/o, obliteration of landmarks, coagulopathy
Alternative to cricothyrotomy?
Needle cricothyrotomy w/ transtracheal jet ventilation
Indications for needle cricothyrotomy w/ transtracheal jet ventilation?
Acceptable in peds, safer in coagulopathy
Does needle cricothyrotomy w/ transtracheal jet ventilation protect the airway?
No
What does needle cricothyrotomy w/ transtracheal jet ventilation require?
Clear upper airway passages and oral/nasal airway devices
Procedure diagram
What is the importance of pre-oxygenation?
Extends the duration of safe apnea
What is safe apnea defined as?
The time until a patient reaches a saturation level of 88% to 90%
Process of pre-oxygenation?
De-nitrogenating residual capacity of the lungs to maximize O2 storage w/in the lungs
In a patient breathing room air before rapid sequence tracheal intubation (PaO2 90-100) desaturation will occur in how long between sedative/paralytic administration and airway placement (and how it can change with pre-oxygenation)?
in the 45-60 seconds between the two
*3 min HIGH FLOW O2 (NC+NRB) WILL INC TIME UP TO 8 min
Positioning of the patient for pre-oxygenation in order to maximize upper airway dimensions/promote airway patency?
Position pt w/ external auditory meatus on same horizontal plane as sternal notch (20 degrees from horizontal), or reverse trendelenburg
OOPS mnemonic of failed intubation desaturation?
Oxygen, On, Pull mandible forward, Sit patient up
What is a bad combination for ventilation and oxygenation?
Combining loss of tone with recumbency, oral obstruction by tongue, alveolar collapse
What are the four phases of a mechanical breath?
Triggering, Inspiration, Cycling, Expiration
What is triggering (phase of mechanical breath)?
Transitioning from expiration to inspiration caused by elapsed time or patient initiation
What is inspiration (phase of mechanical breath)?
Flow of gas from ventilator to patient (set for specific volume of pressure)
What is cycling (phase of mechanical breath)?
Transitioning from inspiration to expiration d/t decreased flow, elapsed time, or delivered volume
What is expiration (phase of mechanical breath)?
Ventilator flow stops & gas passively flows out of lungs
Where is the volume control/assist control (VC/AC) ventilator mode most commonly used?
ED
Volume control settings in VC/AC ventilator mode?
Target tidal volume 6-8mL/kg, and respiratory rate 10-14 breaths/min are set
Assist control settings in VC/AC ventilator mode?
Patient effort triggers breath (delivered at set volume or pressure), a breath will be automatically delivered if not initiated by the patient within a set time
Advantages of VC/AC ventilator mode?
Dec work of breathing, guaranteed minute ventilation
Disadvantages of VC/AC ventilator mode?
May lead to excessive inspiratory pressures
Other ventilator modes (other than VC/AC)?
PC/AC (pressure control/assist control), SIMV (synchronized intermittent mandatory ventilation), PSV (pressure support ventilation)
PEEP! watch lecture !
What can ARDS be secondary to (oxygenation wise)?
High tidal volumes from oxygenation
How to prevent ARDS secondary to oxygenation?
-Use low tidal volumes (6mL/kg) and limited distending pressures
*tidal volume set according to predicted body weight based on height
-Increase PEEP & place in prone position once ARDS begins
*higher PEEP in pts w/ obesity or ascites
