Ventilators All you need to know is Types

Ventilators All you need to know is…

Types • Two types in general, volume control and pressure control. • Pressure control primarily used in children • Volume control is much more common for transport.

Use of Ventilator • Supports two primary functions: w Oxygenation- delivering oxygen to the lungs w Ventilation- exchanging gases: oxygen in, carbon dioxide out.

Oxygenation • Providing the patient with adequate oxygen • If there is an injury to the lungs we may need to increase the amount of oxygen delivered.

Oxygenation • To increase oxygenation, we can increase the fraction of inspired oxygen (Fi. O 2) which will put more oxygen into the alveoli. • Increase the Positive End Expiratory Pressure (PEEP) which will open up more alveoli (recruitment) allowing for better gas exchange.

Ventilation • Ventilation requires an exchange of gas at a particular minute ventilation (the volume of air exchanged in 1 minute or rate x tidal volume). • Ventilation can be adjusted by changing the rate of breathing or the amount of each breath (tidal volume)

Monitoring: How do I know this is right? • Pulse Oxymetry (Sp. O 2): Measures the amount of oxygen bound to hemoglobin (given in a percentage). w May be falsely elevated in poisonings (CO, CN) w If less than 92% increase Oxygen or amount of lung used to breath (PEEP) w Does not measure ventilation, CO 2 can build up to dangerous levels even when O 2 is 100%

Monitoring: How do I know this is right? • End Tidal Carbon Dioxide (ETCO 2): Measures how much CO 2 is coming out of the lungs w A measure of ventilation, tells you how much of the bad is getting out and whether or not your tune is good w Also important measure of resuscitation. w Can effect the amount of blood flowing to the brain. DO NOT ALLOW ETCO 2 TO FALL BELOW 30 IN A HEAD INJURED PATIENT UNLESS INSTRUCTED TO DO SO.

What do all these knobs do? • Mode: w Assist Control (AC): delivers as many full volume breaths as are selected, patient will get full volume breath with every initiated breath; best for the unconscious / unresponsive patient w Intermittent Mandatory Ventilation (IMV) or Simultaneous IMV (SIMV): delivers breaths synchronized with the patients spontaneous rate of breathing. Requires pressure support to compensate for tube resistance

What is Non Invasive Ventilation? • CPAP- continuous positive airway pressure. • Bi. PAP w IPAP (Inspiratory Positive Airway Pressure)Provides pressure support at the initiation of a breath to decrease the work of breathing. (10 cm H 2 O) w EPAP (Expiatory Positive Airway Pressure)Essentially PEEP to improve gas exchange (5 cm H 2 O)

NIPPV • Advantages: w Decreases work of breathing w Rests respiratory musculature w Improves gas exchange • Disadvantages w Requires a conscious, cooperative patient w No Apnea alarm or override

Rate • The normal adult respiratory rate is 12 -16 per minute. • An unconscious patient requires even less and may only need to be ventilated 12 per minute. • Patients with an acidosis (high acid levels in the blood) may require more frequent breaths.

Tidal Volume • Tidal Volume (Vt) is the amount of air delivered with each breath. • On average a person requires 6 -8 ml of air per kg. So a 70 kg male should have a Vt of 420 -560 ml. • Using volumes that are too high leads to overventilation, too low and the patient is underventilated

PEEP • Positive End Expiratory Pressure (PEEP): The pressure left in the lungs at the end of the breathing cycle. w Normal or Physiologic PEEP is 5 -7 cm of H 2 O. w PEEP prevents lung sacs (alveoli) from collapsing shut. This allows more lung are for breathing (increasing the PEEP will increase the Sp. O 2). w High levels of PEEP and Tidal Volume will increase pressure in the chest and decrease blood flow to the heart and blood pressure.

Pressure Support • Decreases the resistance of the breathing tube. • Usually set at 10 • Does not apply to Assist Control mode

Oxygen Concentration • Fi. O 2: The percentage of oxygen delivered. Should be as little as is necessary. • Often patients will only require 50% Fi. O 2 • Patients with unknown injuries or illness should be oxygenated at 100%

I: E Ratio: Inspiratory-to-expiratory duration • Normal is 1: 2 • Can be adjusted by changing the flow rate w ↑ inspiratory flow rate ↓ time for lung inflation ↑ I: E ratio (i. e. 1: 2 1: 4) • If I: E falls below 1: 2, lungs may not empty completely w Hyperinflation w Increasing peak pressures (Volutrauma) • If > 2: 1 cardiac output may be diminished by increased intra-thoracic pressure.

Vent Orders • AC/12/700/5/70% • What does this mean? (Assist control at a rate of 12, VT 700, PEEP of 5, and 70% oxygen) • How much does this patient weigh? (70100 kg) • Is this the right setting for a patient who is awake and taking some spontaneous breaths? (SIMV is better)

Trouble Shooting • High CO 2 • May need to increase respiratory rate or tidal volume • Low CO 2 • Leaks • Hyperventilation • Cardiac Arrest • Low Saturation • Monitor is not correlating • Increase O 2 • Increase PEEP as long as Peak Pressures are <40

Trouble Shooting • High Pressure alarm • Look for occlusions • Check for Pneumothorax • Decrease tidal volume • Low Pressure alarm • Check the tube (balloon) • Check the connections

Questions? • What do you do if you can not oxygenate a patient with 100% oxygen and a high PEEP? • What do you do if the vent fails? • What do you do if your vent alarms despite the trouble shooting procedures? • (THE ANSWER TO ALL #3 IS BAG!)