Mechanical Ventilation Flashcards
Difference between the 2 types of non-invasive venilation
CPAP (continuous positive airway pressure) - no ventilatory assistance; just improves oxygenation by opening the alveoli and improves hemodynamics by decreasing afterload/preload to improve LV function
BiPAP: continuous positive airway pressure + set inspiratory pressure to assist the ventilatory muscles in their effort to generate inspiratory flow, decreasing the WOB
Indications for CPAP?
OSA
Cardiogenic pulmonary edema
Acute on chronic respiratory failure (i.e. COPD exacerbation)
Indications for BiPAP?
Acute on chronic respiratory failure (i.e., COPD exacerbation)
Other forms of ventilatory failure (neuromuscular disease)
Onc/bone marrow transplant patients w/pneumonia
Acute pulmonary edema (while diuresis works)
Contraindications to non-invasive ventilation?
Significant secretions
Facial trauma/burns/other anatomic problems w/mask seal
Aspiration risk
NNT w/non-invasive ventilation to avoid intubation?
2
Indications for MV?
Anyone who looks like they will die without intubation in the next few minutes
Ventilatory problems (apnea, impending respiratory muscle fatigue, etc.)
Oxygenation problems (hypoxia, etc.)
Protection of the airway
Secretions
List the 4 most commonly used modes of MV.
ACVC
ACPC
SIMV
PS
What 3 things does the mode determine?
How the ventilator initiates the breath (trigger)
How the breath is delivered (limit)
When the breath is terminated (cycle)
ACVC - trigger, limit, cycle?
Trigger: patient or time (negative airway pressure or inspiratory flow)
Limit: flow rate and pattern (constant = square vs. decelerating = ramp)
Cycle: volume (flow lasts until the set TV is delivered)
Compare square vs. ramp
Square: minimize inspiratory time to maximize expiratory time (i.e., obstructive lung disease)
Ramp: ventilate a heterogenous lung (i.e., ARDS)
Purpose of PEEP?
Prevent atelectasis
Decrease inspiratory WOB
Improve gas exchange
Advantages to ACVC
Low work of breathing - every breath is supported, TV is guaranteed
Disadvantages to ACVC
Tachypnea can lead to hyperventilation and respiratory alkalosis
Breath stacking can occur when the patient initiates a second breath before exhaling the first, leading to high volumes and pressures (can overcome w/optimal settings and sedation)
Compare SIMV and ACVC.
Like AC, SIMV delivers a minimum number of fully assisted breaths per minute that are synchronized w/patient effort. However, off-cycle breaths are not assisted.
Identical modes in patients who are not breathing spontaneously due to heavy sedation or paralysis
In SIMV, set a ___ RR to limit the opportunity for spontaneous breathing.
High
Advantage of SIMV?
“exercise” the respiratory musculature
Disadvantage of SIMV?
May increase WOB and cause respiratory muscle fatigue