Ventilators for Interns Created: March 2015 Updated: Feb 2016 Amy Ni (Created), Kimberly Truong (updated)

Understand indications for intubation Objectives Understand indications for intubation Understand basic settings of ventilators Ventilation parameters: Respiratory Rate, Tidal Volume Oxygenation parameters: FIO2, PEEP Familiarize with two common vent modes: AC and PS Troubleshoot common vent problems There are 174 methods of positive pressure ventilation!! But this is actually much more complicated than it needs to be.

When to intubate? Cannot protect airway (ie: obtundation) Hypercapneic respiratory failure Hypoxic respiratory failure Impending respiratory failure due to severe work of breathing (ie: during septic shock)

What you set (order) TALKING POINT: This slide is to introduce viewers to what a ventilator display looks like. Then go over the parameters they set and the parameters that are observed.

What is observed (actually happening)

Understanding basic settings of vent parameters— 1) Ventilation Ventilation (CO2 exchange) is affected by tidal volume and respiratory rate. Setting the Tidal Volume: Tidal volumes should 8-10cc/kg of ideal body weight Ideal body weight is based on height and gender Special note: In ARDS, tidal volume between 5-8cc/kg Setting the Respiratory Rate: Usually 12 to 16 For tachypneic patients: tend to start off with higher RR

Understanding basic settings of vent parameters— 2) Oxygenation Oxygenation is affected by FIO2 and PEEP. Setting FIO2: Usually initial FIO2 is 100% SaO2 goal – Most patients: 90-95%, CO2 retainers: 88- 92% Titrate down your FIO2 based on SaO2 Setting PEEP (Positive end expiratory pressure): Usually depends on your disease process Common PEEP setting: 5 If ARDS or CHF, then higher

Volume Control: you set the tidal volume Modes: the basics 1) Assist Control: A common mode where you set a preset tidal volume or inspiratory pressure. You also set the respiratory rate, but note that patients can also trigger additional breaths. Volume Control: you set the tidal volume Constant tidal volume, variable pressure delivered to pt Note: Watch your Peak Pressures and Plateau Pressures with this setting Pressure Control: you set the peak inspiratory pressure Constant pressure, variable tidal volume delivered to pt Limits peak inspiratory pressure to avoid barotrauma

Typically used during weaning Modes: the basics 2) Pressure Support (aka “CPAP trial”): No set tidal volume or inspiratory pressure. Patient initiates all breaths on own with their own appropriate tidal volume. Typically used during weaning Common settings-- Inspiratory pressure: 10, PEEP: 5 When weaning, why do patients need inspiratory pressure and PEEP? Because the ET tube has a lot of resistance Peak inspiratory pressure allows patient to overcome resistance of tube

Troubleshooting the vent Presented as clinical cases Department Name | Month X, 201X

Case 1: You are the night ICU intern. A nurse pages you and says: “Hey doc, the vent is beeping and it says that the peak pressure is pretty high all of a sudden, can you come take a look?” What does this mean? What do you do next?

Case 1: Basics of Peak and Plateau Pressures What is Peak Pressure? It is the highest pressure level used to successfully deliver a breath Normal is <35 cmH2O It reflects airway resistance + lung compliance Airway resistance means endotracheal tube + patient’s airways Lung compliance means patient’s chest walls and lung parenchyma What is the next step when it is high? Find out why it is high  Check Plateau Pressure by pressing “Inspiratory Pause” What is Plateau Pressure? Static measurement lung compliance only

Case 1: Differential Diagnosis of High Peak Pressure High Peak Pressure, Normal Plateau Pressure High Peak Pressure AND High Plateau Pressure Think: “Lung compliance is okay, airway resistance is not” Mucous plug Bronchospasm Patient biting tube Tubing disconnected Think: “Lung compliance is worse.” Worsening ARDS Pulmonary edema Pneumothorax Pleural effusion ETT in wrong bronchus

Case 2: You admit a 34 year old female for severe asthma exacerbation requiring intubation. Two hours after intubation, the nurse calls you: “Doc, I think we need to start antibiotics and levophed now! Her blood pressure dropped from 130’s systolic to 70’s! And she’s de- satting!” What are you concerned for? What do you do next?

Concern for: Auto PEEP, aka “breath stacking” or “air trapping” Case 2: Concern for: Auto PEEP, aka “breath stacking” or “air trapping” Expiratory time is too short (recall COPD/asthma patients may need prolonged expiration to “blow off CO2”) Leads to overinflation of lungs, poor ventilation  hypoxia Also leads to poor venous return  hypotension

Ways to treat auto-PEEP: Case 2: Ways to treat auto-PEEP: Decrease RR and/or tidal volume Increase the E in I:E ratio (advanced) Increase sedation/analgesia/even adding neuromuscular blockade (advanced) In severe cases  disconnect ventilator to allow full expiration and watch for rise in blood pressure

Learned when to mechanically ventilate: Summary Points Learned when to mechanically ventilate: Cannot protect airway, obtundation, increased work of breathing with impending respiratory failure, high CO2 or low O2 Learned basic settings: Assist control vs. pressure support Common setting at UCI: AC VC Common parameters: RR 12, VT 500, PEEP 5, FiO2 100% Learned two common vent modes: AC and PS PS for weaning, also know as “CPAP trial” Two bonus cases Learned difference between peak and plateau pressure Learned breath stacking in obstructive airway disease