We Have No Beds: Ventilator Series
Noninvasive Ventilation - Part 1
Written by Dr. Ashley Binder, edited by Dr. Sukhi Bains
It’s a busy night in the ED and in comes…
…a 60 y/o male with OSA and COPD in extremis, sitting up on the gurney gripping the side rails, huffing and puffing, struggling to breathe. You are informed that he has not used his CPAP in two weeks, is not on home oxygen, and ran out of his COPD meds weeks ago. EMS has him on a non-rebreather.
You look at the monitor as he gets hooked up…
You start your resuscitation but he still looks bad. You are eyeing the GlideScope® in the corner and start to talk to him about intubation. The patient is alert and oriented and adamant about not wanting to be tubed. What do you do?
You consider your non-invasive options of ventilation, as this patient is clearly failing on the non-rebreather. He uses CPAP at night. But, is that enough, since this patient is also not ventilating in addition to not oxygenating? Maybe BiPAP then? What’s the difference? The nurse is calling the respiratory therapist to the room so let’s quickly go over your options.
Non-Invasive Ventilation or Non-Invasive Positive Pressure Ventilation (NIV or NIPPV) is a way to provide ventilation support to patients in respiratory failure without having to use an endotracheal tube (ETT) or tracheostomy tube. Typically, this form of ventilation is delivered through face masks, nasal pillows, or more recently, helmets.¹
When to consider NIV…and when you really shouldn’t:²
USE NIV in patients who have 2 or more:
Accessory muscle use
RR of 25 bpm or more
PaCO2 > 45mmHg and pH < 7.35
PaO2/FiO2 ratio <200
DNI or DNR order
AVOID NIV in the following:
Cardiac or Hemodynamic instability
Uncooperative behavior by the patient
Burns or trauma to the face
Significant aspiration risk
An abundance of secretions
Anatomic abnormality that would affect gas delivery
Your patient falls into the first column and doesn’t have any contraindications so let’s try some NIV.
NIV breaks down into two forms: Continuous Positive Airway Pressure (CPAP) and Bilevel Positive Airway Pressure (BiPAP). What's the difference?
Used in OSA
Helpful with oxygenation issues at night
May set EPAP
May set FiO2
Cannot set respiratory rate
Can use in respiratory distress
Helpful with ventilation and oxygenation issues
May set EPAP and IPAP
May set FiO2
May set a respiratory rate
EPAP– expiratory positive airway pressure (EPAP) that keeps the patient’s airways open
IPAP– inspiratory positive airway pressure (IPAP) that aids in ventilation by controlling tidal volume
You note that your patient is in respiratory distress and needs ventilatory support. Considering all of this, you have clearly determined that the patient should be placed on BiPAP.
How do I decide the settings?
The respiratory therapist is now staring at you requesting settings… “10 and 5” rings a bell, but why? Where did this come from?
Guidelines recommend that when initiating BiPAP:
IPAP should be set at a pressure between 8-12cm H20
EPAP should be set between 3-5cmH20
**Note that any pressure below 4cm H20 for the EPAP can lead to rebreathing of CO2.²
Ok, so 10 and 5 are fine for a start. You also should set a rate, or at least a backup rate of 8 breaths/min and an FiO2, which you can base on the patient’s needs. Make sure to request an ABG in 1 HOUR so that you can reassess your settings.
Your patient starts to look better and breathe a bit easier, you are off to see the next patient but remember to check back with him soon to make sure he is still improving.
Guy W Soo Woo MD, MPH, et al. “Nonivasive Ventilation.” Medscape: Oct 12, 2016. https://tinyurl.com/gvpm2no
Wilkins, Robert L, PhD, RRT, et al. Egan’s Fundamentals of Respiratory Care, eighth edition. St. Louis: Mosby, 2003: 1059-1080.