Critical Care Flashcards
Intubation and Mechanical Ventilation:
Who needs it
- Respiratory failure: lose the ability to ventilate adequately
- Hypoxemia
- Hypercarbia
- Inability to protect airway
- Failed non-invasive ventilation (BiPAP or CPAP)
- Procedures requiring general anesthesia
Rules for Intubation
- Always intubate under direct visualization of the vocal cords
- Always confirm ET tube placement with auscultation of all lung fields
- Follow up with a chest x-ray
- Proper position of ET tube is 3- 5cm above the carina
complications of ventilhation
- Reduced MAP after intubation and implementing mechanical ventilator support is common due to:
- Reduced venous return from positive pressure ventilation
- Reduced endogenous catecholamine secretion
- Administration of drugs used to facilitate intubation
- Usually volume responsive hypotension
What is the preferred method of ventilation for long term vent management
Tracheostomy
indications for tracheostomy
- Long-term or permanent airway obstruction
- Long-term mechanical ventilator
- Unable to clear their airway secretions
- Facilitate liberation from mechanical ventilator
benefits of tracheostomy
- Improved oral hygiene
- More comfortable
- Need for less sedation
- Can progress to speaking valves and normal eating practices possibly
- Decreases airway resistance and dead space -> lead to faster ventilator wean
- Easy access to airway
complications of tracheostomy
- Acute
- Hemorrhage
- Mal-positioning
- Pneumothorax/pneumomediastinum
- Neck hematoma
- Long Term
- Tracheoesophageal fistula
- Tracheo-innominate fistula
- Tracheomalacia
- Tracheal stenosis
name 4 types of ventilhator modes
- Ventilator modes:
- Volume control
- Pressure control
- Pressure support
- Non-invasive ventilation: BiPAP
Complications of mechanical ventilhation
- Barotrauma – pneumothorax, SQ emphysema, pneumomediastinum, pneumoperitoneium, alveolar rupture
- Lung injury
- Ventilation/perfusion mismatch
- Decreased hemodynamics
- Myopathy
- Ventilator assistant pneumonia
•Patients who can be Extubated
- Is the patient stable on minimal ventilator settings?
- FiO2 <50% with PaO2 by blood gas>60
- PEEP<10
- PS<7
- Did the patient pass a spontaneous breathing trial (SBT)?
- PSV with PS typically of 7 and PEEP of 5 (some institutions will do PS of 0)
- Rapid-shallow breathing index (RSBI) <100
- Ration of RR to TV
- No evidence of increased work of breathing or hemodynamic instability
•Fraction of inspiration oxygen (FiO2)
- Definition: fraction of oxygen in the volume being measured
- Room air: 21%
- 1-2L via nasal cannula: 25%
- 10L via nonrebreather: 50%
•Should be on the lowest possible FiO2 necessary to meet oxygenation goals, usually peripheral saturations between 90-96%
•Increased FiO2 can lead to oxygen toxicity, parenchymal injury, hypercapnia, and absorption atelectasis
•Positive end expiratory pressure (PEEP)
- Definition: pressure added at the end of expiration that prevents alveolar collapse
- Usual initial dose if 5 cm H20 but can increase up to 20 cm H20
- Recruits alveoli that have collapsed, which increases the surface area for gas exchange
- ARDS patients are typically treated with low TV and high PEEP
- Increased PEEP can lead to decreased cardiac function, barotrauma, and impaired cerebral venous outflow
•Tidal Volume (TV)
- Definition: the amount of air delivered with each breath
- Ideal TV is 6-8 mL/kg of IBW à use IDEAL weight
- Patients with ARDS should have low TV of <6 mL/kg of IBW
•Pressure Support (PS)
- Definition: a set pressure that is delivered during inspiration (driving pressure)
- Can be set anywhere from 0-30 mmH20, normal is usually 7-10 mmH20
- The higher the PS, the larger the patient’s TV will be
Volume Control
- These are good “set it and forget it” modes
- Less useful for awake patients
- Can be very uncomfortable for patients
Synchronized intermittent mandatory ventilation
- A good starter weaning mode that allows patients to take independent breaths between set breaths.
- Patient triggered breaths will not receive the set TV, but will receive the set PS
- Better preservation of respiratory muscle function
- If patient is tachypneic there is a high likelihood of vent dyssynchrony
Assist Control
- A good mode for patients that are sedated or newly intubated
- Clinicians set the minimal minute ventilation by setting the RR and TV
- Patient triggered breaths will receive the set TV
- If patient is tachypneic there is a high likelihood of Auto-PEEP (incomplete expiration prior to the initiation of the next breath leads to air trapping)
Pressure Control
Each breath is given a set amount of pressure via the ventilation
- The clinician is setting the inspiratory pressure and inspiratory time
- The resulting TV depends on the set driving pressure, TV will be varied
- Advantages: Can have strict control over the airway pressure which can help with barotrauma and fresh suture lines
Disadvantages
- Can not wean from this mode
- Can be very uncomfortable
Pressure Support
Only set the pressure support and PEEP
- The patient’s TV and RR are not set, rather the patient receives assistance with each breath
- Patient needs to initiate the breath
- The preset variable is the set amount of PS and PEEP
- Ideal for weaning
- More comfortable mode
Patient’s need close monitoring due to no set TV and minute ventilation and can lead to hypoventilation
Non-invasive ventilation: BiPAP
Used for non-intubated patients
- Used for patients with impending respiratory failure or who is struggling after extubation
- BiPAP provides assistance with the mechanics of ventilating (regulating oxygen and carbon dioxide)
- Can adjust the inspiratory and expiratory pressures to achieve a desired TV
Advantages:
- Can prevent intubation
- Intermittent use
Disadvantages:
- Claustrophobic, patients tend not to tolerate it
- Patient’s can not eat or drink while mask is on
- Can dry up secretions and cause a mucus plug
define Acute Respiratory Distress Syndrome (ARDS)
- Acute, diffuse, inflammation form of lung injury that is associated with a variety of etiologies
- High mortality rate: ~30%
criteria for dx of ARDS
- Bilateral infiltrates on chest x-ray
- Progressive respiratory failure
- Hypoxemia that does not respond to increase FiO2
most likely causes of ARDS
- Sepsis
- Pneumonia
- Trauma
- Multiple transfusions
- Aspiration of gastric contents