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Capnography's Role in Traumatic Airway Intubation

Does your system have specific protocols on managing ventilation of head-injured patients? Photo Courtesy Christopher T. Stephens, MD

Greetings colleagues,

To begin this last article in the three-part series on managing the traumatic airway, let’s review briefly what has been done at this point. Either you have successfully or unsuccessfully intubated your trauma patient, have gone for a supraglottic airway device or have chosen to hand ventilate the patient during transport with an oral/nasal airway and bag-valve mask (BVM).

The only other option is a surgical airway. We will briefly review these techniques but I warn that you MUST practice these on suitable mannequins or cadavers in a laboratory setting. Another alternative is to purchase some pig tracheas or similar and practice your surgical skills on these.

The point is that practice allows you to appreciate the anatomy and understand the skill. Most EMS protocols use a needle cricothyroidotomy technique in which the cricothyroid membrane is identified between the thyroid and cricoid cartilages. (I encourage you to identify this important landmark on yourself, then your family and friends, followed by practicing on your patients as part of your physical exam.) Once you’re comfortable finding this landmark on many people, it will come second nature in an emergency. Be certain that you’re familiar with the needle cric device/supplies that your system uses; once the needle is in place, either a wire is placed through it to allow for a trochar tracheostomy tube to be placed over the wire or the large bore catheter remains in place for ventilating with a BVM.

Again, however your service trains and uses this technique, be sure to cover it regularly with training. An alternate technique is the open surgical cricothyroidotomy, where a scalpel is used to make a vertical incision over the cricothyroid membrane to identify the membrane. Once identified, make a horizontal stab with the scalpel, followed by flipping the scalpel and placing the handle end in the incision and twisting 90 degrees to enlarge the opening.

At this point, there’s likely a fair amount of blood to deal with so make certain that your partner has suction and 4X4s to blot away the blood. Now you can do one of two things. You can go straight for a smaller endotracheal tube (ETT), such as a 6.0 or 6.5, and place it in the surgical opening. Or you can place a bougie intubating stylet into the opening so that you have something in the airway to guide your ETT over and into the trachea. This is a nice technique to use so that you don’t lose your surgical opening while trying to place the ETT into the hole. Try this on the cadaver, animal tracheas or appropriate mannequin. There are many ways to accomplish a surgical airway and these are some of the ways that we have found useful for teaching our local medics.

So now you have an airway to manage en route to the hospital. We will assume that you have an intubated patient from the case introduced in the first article of the series, “Managing the Traumatic Airway.” Once the tube is secured and you are ready for transport, be certain to re-assess the tube placement once packaged in the ambulance or aircraft. I still find many right mainstem intubations once delivered to me at the trauma center.

Once you’ve determined that the patient has bilateral breath sounds and equal chest expansion, take a quick look at your capnography monitor and pulse oximeter. Are you happy with the waveforms and numbers? These numbers can guide your therapy and airway management throughout transport. Is the patient on 100% FiO2? Be certain that oxygen is reaching the patient! Do you need to suction out the ETT? Make sure that you are able to adequately exchange gases via the ETT for your patient throughout transport.

This is where capnography is so valuable. If your patient still has a blood pressure and pulses, you should pay very close attention to your capnograph waveform. It will let you know if there’s an obstruction between your patient and the end of the ETT by the slope of the waveform. In addition, it will give you insight into your patient’s perfusion status. If a nice, normal waveform is present, then your patient is perfusing adequately enough for cellular respiration to take place.

Note: Your patient may still be in the early stages of shock, and you should always be vigilant for signs of continued blood loss. If your patient is in profound shock, in extremis or arresting, then your capnograph waveform will be distorted with low numbers. Again, this monitor is important for you to use and understand for your intubated patient management in the field. Please take the time to read about, practice and understand waveform capnography. Spend some time in the emergency department looking at ventilated patients who have capnography waveforms on the monitor. This will help you begin to understand the concepts of using this important monitor for sick patients.

If your patient has signs of a traumatic brain injury, what you do with your ventilation management becomes VERY important. You must maintain your end¬-tidal carbon dioxide numbers between 30–35 mmHG to prevent either hypo- or hyperventilation with subsequent cerebral perfusion abnormalities. Please read up on this and discuss with your medical director. Only patients showing signs of tentorial herniation should be mildly hyperventilated in the field, avoiding end tidals lower than 28 mmHg!

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If your system still isn’t using continuous capnography on your monitor, it will be important for you to at least monitor continuous pulse oximetry and end-tidal using a colorometric easy cap device during transport to ensure correct tube placement. We all need to aim for zero misplaced endotracheal tubes in the field. If there is ANY doubt, take the tube out! This is a very important concept. It’s much better to assist an airway with a BVM and oral/nasal airway (or a supraglottic device) than have a misplaced tube on arrival at the trauma center!

I hope that these articles have given you some tools to use in the field when faced with a trauma airway. Remember to read, discuss with colleagues and medical directors, and practice airway maneuvers whenever possible! A great place to start is by attending a cadaver airway lab in your area or sign up for one at a national conference. I wish each of you the best of luck in your EMS career and please feel free to contact me anytime with questions or concerns. I am here for all of you field providers! Work hard and do the very best for your patients.

Part I: Managing the Traumatic Airway
Part II: Trauma Airway Intubation Is a Team Effort

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