Airway Notes: The Laryngoscope

In this week’s installment of Airway Notes, we take a look at the laryngoscope used for direct laryngoscopy (DL). DL is becoming a less commonly used skill in favor of video laryngoscopy (VL), but I think it is still an essential skill for airway management. There are 2 main types of blades, the Miller and the MacIntosh and each has its benefits and proponents (I’m a Mac guy, myself). You should be familiar with the use of both, but focus on mastering one before moving on the other.

In the IG post, I show examples of a slightly different way to hold the laryngoscope than how most of us were probably taught. This was taught to me by one of my attendings, an anesthesia critical care physician named Habib Srour. Habib is an incredibly smart guy and when he showed me this technique it instantly made so much sense. It takes the pressure off of the hand and wrist and allows the hand and lower arm to serve as one unit. The force of lifting then is transferred to the elbow and ultimately to the shoulder and upper arm, MUCH stronger than the wrist and forearm. This allows for more lifting force without the urge to rock backwards on the handle, risking damage to the teeth and lips. It is probably the single best tip I’ve gotten in regards to DL.

Airway Notes: Bag Mask Ventilation

So, I’m starting a new mini-series called “Airway Notes” over on my Instagram. Each Friday (sorry it’s a day late for the first one!), I’ll be covering a little bit of airway management. This week, we’re going to discuss the most important airway management skill, bag mask ventilation. So, head on over to Instagram and check it out. If you’re not already following me on Instagram, this is a great reason to start! Check back every Friday for more. My plan is to eventually move on to other topics and make Friday the day when these original posts show up.

Tracheoinnominate Fistulas

There are a number of potentially scary complications from tracheostomies, particularly early on in the post-procedure period. Although accidental decannulation and loss of airway is probably the most common, Brandon Oto describes the management of a much scarier complication in the latest in our TIRBO series on the Critical Care Scenarios podcast.

I’ve never experienced one of these (thank goodness), but I have had to rush to the OR with a bleeding ENT patient and they’re some of the scariest scenarios that we encounter in the ICU. I think Brandon is right on when he says that just because the incidence of these types of things is low and the mortality is high doesn’t mean that we should be fatalistic and use that as an excuse not to be prepared for these.

Waveform Capnography

While we’ve used colorimetric capnography for years to confirm ETT placement, not all ICU providers are as familiar with waveform capnography. It offers significant benefits to the intubated and non-intubated patient alike.

Using waveform capnography to confirm ETT placement offers a benefit over colorimetric confirmation. during the peri-intubation period, while the patient is being ventilated via BVM, there can be an accumulation of CO2 in the stomach so that it is possible to get color change on an esophageal intubation. The use of waveform capnography prevents this. As carbon dioxide is not manufactured in the stomach, eventually the levels will fall. So, by trending the waveform over a few breaths, you should see a steady decrease in end-tidal CO2 over the course of a few breaths.

In addition to ETT positioning, ETCO2 has a number of other benefits including detecting displaced ETTs, monitoring effectiveness of ventilation in non-intubated patients, assessing ROSC during CPR, and much more. But essential to its use is understanding how to interpret the waveform and not just read the number. In this video, Obiajulu Anozie (@icuexplained) does a great job of explaining what the waveform means and how to use it in the ICU.

The ROX Index, and “How Much Flow?”

I love high flow nasal cannula (HFNC) oxygenation. It’s a great and simple tool to improve oxygenation, ventilation, and work of breathing in people who are struggling but may not need intubation. It’s also a great tool to use when you extubate someone who is a little marginal. We’ve all that experience of the patient who technically meets the criteria for extubation but your gut tells you they may have a hard time. Extubation to HFNC can help them fly following removal of the tube. It can also be used to prevent intubation in someone who is on the fence. But, how do you know who it will work for?

Dr Eddy Joe Gutierrez has a nice post regarding the ROX (Respiratory rate-OXygenation) Index. It’s a simple calculation that can be used to predict who will benefit from HFNC to reduce work of breathing and impending respiratory failure vs who just needs to get intubated. To get the ROX Index, just divide the ratio of SpO2/FiO2 by the respiratory rate. The SpO2/FiO2 ratio is similar to the PF ratio, but using the pulseox instead of having to grab and ABG. Eddy Joe points out that you’ll want to actually count the respiratory rate and not use the number that all to often gets erroneously charted. MDCalc has a calculator here to make it easier. ROX ≥ 4.88 is a good indicator of HFNC success. Lower than that, there is risk that HFNC will fail and you’ll need to intubate anyway. See Eddy Joe’s whole post for more details.

Another thing that this post addresses is the question, “how much flow should I start my patient on?” This is often an issue when providers have little experience with HFNC. When we first started using it, I would frequently find patients on 100% FiO2 and 10lpm of flow. This is the exact wrong way to use HFNC. The real benefit is the flow, not the FiO2. Eddy Joe points out that he typically starts with 50lpm, and this is roughly where I usually start as well. Some people won’t tolerate that much flow, but starting high gives you some wiggle room. If they are uncomfortable with 50, drop down to 40. Odds are, by comparison, this will be more pleasant and you’ll have a little great success than if you start low and go up. Eddy Joe shared a study on Twitter the other day that found that 30-40lpm is the optimal flow rate to use. So, it’s nice to have data to back up what my experience/gut had showed me. Read the entire study here.

So, if you’re not using HFNC, you should. If you are, try the ROX index to guide you. Also, start your flow high. Remember, the real benefit is in the flow and for that you need high rates, at least 30lpm.

Neurocritical Care Intubation

This is an older episode from the EM:Crit podcast, but it’s good and still mostly true. Part of Scott Weingart’s “The Laryngoscope as Murder Weapon ” series, “The Neurocritical Care Intubation.” This discusses some of the pitfalls in intubating a patient in the neuro ICU and ways to avoid them. Note, we don’t always do these things, but there’s a lot of good stuff in here to talk about.