Ventilator Flashcards
Trigger
WhT triggers the ventilator to deliver a breath.
Usually trigger is negative pressure, as soon as diaphragm goes down the machine senses a negative pressure and delivers a breath
U can adjust the sensitivity of the trigger don’t have it too high or too low, if too high it will deliver breath every time it senses negative pressure and can cause barotrauma
Capnography
Capnography is the monitoring of the concentration or partial pressure of carbon dioxide (CO
2) in the respiratory gases. Its main development has been as a monitoring tool for use during anesthesia and intensive care. It is usually presented as a graph of expiratory CO
2 plotted against time, or, less commonly, but more usefully, expired volume. The plot may also show the inspired CO
2, which is of interest when rebreathing systems are being used.
The capnogram is a direct monitor of the inhaled and exhaled concentration or partial pressure of CO
2, and an indirect monitor of the CO
2 partial pressure in the arterial blood. In healthy individuals, the difference between arterial blood and expired gas CO
2 partial pressures is very small. In the presence of most forms of lung disease, and some forms of congenital heart disease (the cyanotic lesions) the difference between arterial blood and expired gas increases and can exceed 1 kPa.
MV ( minute volume )
Volume of breath that is delivered by the machine every min.
It is a product of respiratory rate and tidal volume
Respiratory rate:
Number of breaths per min that is delivered by the ventilator
Tidal volume
The volume that is delivered to the lungs each breath
Normal tidal volume is 8 ml/ kg
Ards: 6 ml/ kg
Ways to adjust ur min volume
U can either increase tidal volume or respiratory rate, however there is a limit to increase in tidal volume before u get barotrauma. Respiratory rate however is the best way to adjust ur min volume, increase o2 delivery and decrease co2
Peep
Positive end exploratory pressure.
Positive pressure left in alveoli after expiration. Keeps alveoli open prevents them from collapsing producing shunt and decreasing g ur o2 saturation.
Flow rate
How fast your tidal volume is being delivered. U want it fast so that patient has enough time to expire before the next breath is delivered
Fio2
Fraction if inspired oxygen. From the volume that is delivered to patients lungs, how much of it is o2. We want to keep our fio2 btw 40-60 ( u get 60 when u deliver 50 o2 50 air)
If 1 n2o and 1 o2 then fio2 is 50% if 50% o2 and 50% air then ur fio2 is 60% bc air is 21% o2 and o2 is 100% o2 the fraction is 60%
U don’t want 100% O2 bc it can cause O2 toxicity
Ways to control ur co2
By respiratory rate and tidal volume, u can control it better with respiratory rate than tidal volume. Bc increasing tidal volume can cause barotrauma
Ways to control O2
By peep and fio2
Oxygen toxicility
O2 steals electrons causes free radical production —> acute respiratory distress
Absorptive atalactosis:
Alveoli will collapse as 100 percent of o2 will be picked up by blood there is no nitrogen to keep alveoli open( remember room sir has oy 21% O2
Auto peep
Excess Air trapped in alveoli at the end of expiration sure to inadequate time for expiration. Basically u r putting too much air too fast, lungs can’t get rid of them, alveoli and lung will swell up, barotrauma and reduction in cardiac output
Peak inspiratory pressure
Peak inspiratory pressure (PIP) is the highest level of pressure applied to the lungs during inhalation.[1] In mechanical ventilation the number reflects a positive pressure in centimeters of water pressure (cmH2O). In normal breathing, it may sometimes be referred to as the maximal inspiratory pressure (MIPO), which is a negative value.[2] Peak inspiratory pressure increases with any airway resistance. Things that may increase PIP could be increased secretions, bronchospasm, biting down on ventilation tubing, and decreased lung compliance. PIP should never be chronically higher than 40(cmH2O) unless the patient has Acute Respiratory Distress Syndrome.
