Imagine you have a patient in respiratory failure sitting right in front of you. The patient has an increased work of breathing and obviously in distress. Monitors are beeping, nurses are asking you what you want to do, and if you don’t do something, the patient is going to arrest and potentially die. What is your framework for tackling these patients? Well, I had a chance to sit down with Haney Mallemat and discuss his framework for managing respiratory failure and NIV.
REBEL Cast Episode 46a – Respiratory Failure and NIV with Haney Mallemat
Respiratory Failure – The Rule of 2s (This is a simplified algorithm as there can be mixed respiratory failure)
Two Types of Respiratory Failure:
- Type 1: Oxygenation = Hypoxemic (i.e. CHF)
- Type 2: Ventilation = Hypercarbic (i.e COPD)
Two Settings on NIV to Improve Hypoxemia:
- Increase FiO2
- Increase Positive End Expiratory Pressure (PEEP) – In patients who don’t improve their oxygen saturation with FiO2 alone, consider lung shunt physiology. These patients need PEEP to help recruit atelectatic alveoli to overcome the shunt (CPAP Recruitment)
Two Settings on NIV to Improve Hypercarbia (Increase Minute Ventilation):
- Increase Tidal Volume
- Increase Respiratory Rate
Two Types of NIV:
- Continuous Positive Airway Pressure (CPAP) à Can really only help Type 1 (Hypoxemic) Respiratory Failures as it increases mean air way pressures or increases PEEP
- Bi-Level Positive Airway Pressure (BPAP) à Can help with Type 1(Hypoxemic) and Type 2 (Hypercarbic) respiratory failure
- Inspiratory Positive Airway Pressure (iPAP)
- Expiratory Positive Airway Pressure (ePAP): This alone functions like CPAP
- The Difference between iPAP and ePAP is what will improve TV. In other words the bigger the difference, the bigger the TV.
Two Types of CPAP:
- High Flow Humidified Nasal Cannula (HFNC): Flows can range from 20 – 80LPM and pressures start at 5cmH20 and titrate up to max of 20cmH20. The more flow you produce the more positive pressure you produce. No one really knows the exact amount of CPAP you get with this as it is dependent on patient factors.
- Haney likes to call this Diet CPAP because the patient needs more than wall oxygen, but doesn’t necessarily need a tight fitting mask
- Mask: Generally start at a pressure of 5cmH20 (There are no hard rules that state you can’t start at 4 or even 6). Titrate by 2 – 3 cmH20 every 5 – 10 minutes, but this is contingent on the patient.
- Maximum is 20cmH20: Lower esophageal sphincter pressure has a tone of about 23 – 25cmH20, if you use higher pressures you will insufflate the stomach and potentially cause vomiting and make a bad situation worse
Two Settings on BPAP:
- iPAP: Range 5 – 20cmH20.
- ePAP: Range 0 – 20cmH20. Remember this functions like CPAP, so if you have a patient with pure COPD exacerbation and no Hypoxemia, you could start this at 0cmH20
- Remember it’s the delta or difference in the iPAP and ePAP that affects TV. So don’t just go up on both settings in hypercarbic respiratory failure:
- 10/5 = Delta of 5
- 15/10 = Delta of 5
- 20/15 = Delta of 5
Haney Mallemat, MD
Emergency Medicine, Internal Medicine, and Critical Care Boarded
Cooper Medical School of Rowan University
- Keynotable: Learn how to give powerful presentations
- Resuscitation Leadership Academy (RLA): Yearlong fellowship for those who want to do more resus and critical care but just don’t have the time to do an actual critical care fellowship or leave where they are at:
- Monthly Curriculum
- Video Chats with Critical Care Professors
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Post Peer Reviewed By: Anand Swaminathan (Twitter: @EMSwami)