The Importance of Breathing Clean Air

Breathing is the greatest pleasure in life

Giovanni Papini

“Make it quick and right!” every surgeon says speaking to the anesthetist before intubation.

Do you actually know why it is called Rapid Sequence Intubation? Let us help you!

In this scenario, you’re an Intensivist resident, so you won’t accuse us of speaking only to surgeons! Still, everyone involved in the resuscitation of a patient needs to know what is going on and why in order to help and not just be a spectator!

Your consultant tells you to go to the ED because of an incoming burned patient transported by a BLS (Basic Life Support) ambulance, you need the help of the trauma surgeon on this case…

A – 25 yo male (Mark);
T – 30 minutes ago, arriving in 10 minutes;
M – while cooking the pan caught fire;
I – II grade burns on the neck and face with suspected inhalation injuries;
S – good vitals, SatO₂ 95% with oxygen mask (FiO2 35%);
T – oxygen mask and spinal board for the transport.

The team is composed of the surgeon as a hands-on team leader (Laura) and 2 nurses (Erik and Gabriel).

On arrival, you are at the head of the patient and you have to focus on A and D; meanwhile, Laura will check B, C, and E [see the Trauma Team Management post].

You and Erik:
A – Mark is awake, coughing with carbonous sputum, a Venturi mask FiO2 35% is on, SatO₂ is 95%. You change it with a non-rebreathable mask (FiO2 100%, 15 L/min of oxygen) reaching a SatO₂ of 100%. You know you need to tube him quickly, so you tell Erik to get the drugs and the materials (we’ll get there)!
D – GCS 15, pupils equal and reactive to lights, no lateralizing signs

Laura and Gabriel:
B – Good bilateral breath sounds, normal thoracic expansion;
C – BP 160/100 mmHg, HR 110 bpm, no external bleeding, abdomen soft, stable pelvis, normal limbs, capillary refill 1 sec. 2 IV lines are in, the blood samples have been taken and an ABG is on its way;
E – II grade burns on the face with some areas of III grade, body temp 36.5°C

Let’s stop for a minute and compare the Rapid Sequence Intubation to an elective one to understand the differences:
During elective intubations, patients are fasting for at least 6-8 h and the stomach is empty. This means that the risk of vomiting and aspiration is reduced to the minimum. Plus, there is no rush in the setting you’re in, so you have all the time to let the drugs properly work and not to “traumatize” the patient.
Let’s suppose you have to intubate a patient for elective cholecystectomy, the steps you should take are:

1. Position the patient properly;
2. Pre-oxygenate the patient with a Venturi mask;
3. Start with the premedication drugs (e.g. fentanyl);
4. Start with sedative agents (e.g. propofol);
5. Check the ability to bag-mask the patient;
6. Once you’re sure you can ventilate the patient, you give the muscle-relaxant (e.g. rocuronium 0.6 mg/kg);
7. Bag-mask the patient until the muscle-relaxant has properly worked (around 3-4 minutes for that dosage of rocuronium);
8. Tube the patient.

As you can understand, there are some major differences with RSI. In an emergency setting:

• You don’t have patients with an empty stomach (the risk of vomiting and risk of aspiration is extremely high);
• You should minimize the use of drugs that can lead to hypotension (your patient is already hypotensive!);
• You cannot wait three minutes before the muscle-relaxant (e.g. rocuronium) properly works;
• You should avoid bagging the patient (even though some recent articles reported no differences in aspirations rates between bagged and non-bagged patients).

So how can we overcome those problems?

The game-changer stands in minimizing the time between the patient’s loss of consciousness and the tube securely cuffed in the trachea. This is done by overdosing on the drugs you’ll use to induce the patient. 

Let’s see:

As you can see, the dose of rocuronium used in RSI doubles the dose used in an elective setting. This is done to shorten the onset of muscle relaxation (mainly done to allow good vision and patency of the glottis). In the case of 1.2 mg/kg of rocuronium, intubation is possible within the first 30-60 seconds, as it would be for succinylcholine.

Rocuronium is generally preferred due to the fewer side effects. However, the problem with it is the duration of its muscle-relaxant effect that lasts for 45 minutes (if you decide to use this drug make sure to have sugammadex (its antagonist) nearby or, if it is not available, to be able to bag the patient easily!).

The amount of sedative agents does not change substantially between the two different induction sequences. However, if the patient’s hypotensive state is profound, ketamine is the only drug that does not cause hypotension per se. Midazolam, which has a lower cardiovascular impact than propofol, is a useful adjuvant at a dose of 0.1 mg/kg, allowing to reduce the dose of propofol (i.e. 1 mg/kg instead of 2 mg/kg).

One suggestion: if you are in a calm setting and you decide to use ketamine, we suggest you give a premedication with 0.1 mg/kg of Midazolam (max 5 mg) to avoid the “bad trip” to the patient.   

Now, imagine to tube a patient in an emergency setting, you need to be ready for the worst (because it will happen)… So you need to prepare:

• Suction (ready and working);
• Drugs and fluids to flush them;
• Laryngoscope with the chosen blade (keep a smaller blade and a larger one at hand as well, especially in children), get used to using a longer blade (i.e N°.4) instead of a short one; the long one will reach where the short one doesn’t, not the other way around. Always check that the laryngoscope light works properly (it’s not fun when you finally see the glottis during a difficult intubation and the light turns off… Trust us…);
• Laryngeal masks (in case your intubation failed);
• ETT tubes (always one bigger and smaller ready);
• Oxygen running;
• Facial mask and bag-mask;
• Pharyngeal cannula;
• A gum elastic bougie and/or a intubation stylet;
• Something to fix the tume once in place;
• Surgical airway equipment ready (maybe not opened, but quickly ready);
• BE READY WITH YOUR PLAN B, C, D, ETC…!

Now, let’s suppose we have everything ready for our patient, how to proceed:

1. Preoxygenate the patient with a reservoir mask with at least 10 L/min of oxygen running. Preoxygenate the patient as long as you can (in theory more than 5 minutes). As soon as the patient arrives in your shock room, you have to position the mask on him… You’ll gain some seconds or even minutes!
2. Choose the drugs (inducer and muscle-relaxant);
3. Someone needs to immobilize the neck inline;
4. Inject the drugs with IV boluses while keeping the oxygen mask on;
5. DON’T BAG the patient (if you have properly preoxygenated the patient, his saturation will remain at 100% for quite a while);
6. Laryngoscope in your left hand, slide it on the right side of the tongue, and then slide it until you find the vallecula. Now, charge it (gently! Avoiding the classical learner’s pivotal movement, but rather following the direction of the handle’s long axis (i.e. away and in front of you)). This is not always possible, depending on cervical mobility;
7. Your right hand, manipulating the trachea, helps to bring the vocal cords on sight. When you see them, someone needs to swap your right hand to keep the alignment between the trachea and the laryngoscope;
8. Get the tube and let it slide in between the vocal cords. Once the cuff is below the vocal cords, inflate it and check the correct position. Modern tubes have two black circumferential lines at a distance of approximately 2cm, halfway along the tube. You should aim at positioning the tube with the vocal cords standing between the two lines to reduce the risk of bronchial intubation if the tube is too distal, or unintended extubation if it is too proximal. All ETTs are provided with a built-in ruler; use this to note down the depth of the tube from its tip to the patient’s teeth.
9. Remember that direct laryngoscopy is the gold standard for correct endotracheal intubation. If you see the tube passing the vocal cords, the airway is secure. End-tidal CO₂ and auscultation for symmetric chest expansion become confirmatory. But it is fundamental to see the tube sliding in! Do not abandon laryngoscopy as you jam the tube in, because once in a while you might tube the esophagus;
10. Start listening on the epigastrium (immediately check for esophageal intubation), then check both lungs. Look also at the EtCO₂ to double-check your intubation!

We hope we don’t have to say that if the patient is hypoxic and/or not breathing you have to bag him! Just do it gently with small volumes at a high rate instead of big volumes (this should decrease the amount of air you’ll push into the stomach).

So, where did we leave Mark?

He’s still breathing on his own with the non-rebreathable mask having a SatO₂ of 100%… He looks well oxygenated.
You have Erik ready with the drugs you requested (in this case, you decide on ketamine 100 mg and succinylcholine 100 mg, slightly overdosed for an 80 kg male, you add 3 mg of Midazolam), he has a 7.5 mm tube ready (and an N°.7 and an N°.8 just in case), laryngoscope blade N°.4 and fluids ready to flush the drugs. 
Gabriel keeps the inline immobilization of the cervical spine (yes, in this patient it is not necessary, but you need to be a bit uncomfortable otherwise it is too simple), while Laura is ready nearby in case of need of a surgical airway.
Mark is coughing more and more, you need to move before his airways close due to the edema! 

You: “Erik, give the drugs and flush them!”
Erik: “Midazolam 3mg in, Ketamine 100 mg in, Succinylcholine 100 mg in, and flushed!”

Now, you wait for the succinylcholine fasciculations for around 30 seconds (during which you think to all the things that will go wrong). Mark is now unconscious, the mask is still on his mouth and his SatO₂ is still 100%, other vitals unchanged.
This is what happens next:

• Mark’s muscles fasciculate;  
• You remove the oxygen mask;
• Laryngoscope on your left hand, slide on the right side of the tongue, and push it to the left side; 
• Slide the laryngoscope until you see the vallecula and charge it. Using your right hand, you align the blade with the trachea, obtaining a clear view to the vocal cords (Cormack 2); 
• Laura swaps your hand with hers to keep the alignment between the laryngoscope and the trachea;
• ETT tube N°.7.5 in your right hand, you slide it into the trachea, you see the cuff passing the vocal cords;
• Erik inflates the cuff;
• Laura checks the correct intubation by listening to the sounds on the epigastrium first and then on both sides of the thorax, while you bag the patient;
• Laura verifies the correct intubation and you double-check it by looking at the EtCO₂ curve on the monitor;
• You are responsible for the airway, so it is your responsibility to make sure the tube is properly taped or fastened to the patient’s cheeks (these are generally the most stable supports on the face). You may ask Erik to help in, but you must double-check, because you have to run around for diagnostics and procedures next.

Well done! 
Now the airways are secured… you can continue the resuscitation!
You’ll need to set up proper sedation, maybe with propofol thanks to his hemodynamic stability, and you may need to properly block his muscles (you may switch to rocuronium at this time), but this is beyond the purpose of this post…

Before we leave you, we want to give you a couple of tips and tricks. There are some situations in which you should NOT use the muscle-relaxant agents:

• Suspected expanding hematoma on the pharynx, the larynx, or the neck;
• Unstable airway due to penetrating neck trauma;
• Bleeding airway.

In those situations, the muscles present in the neck (cervical fascias) and around the trachea/larynx/pharynx will partially contain the hematoma/bleeding and also will keep the airway in line. If you decide to use a muscle-relaxant agent those muscles will lose strength letting the hematoma expand and rapidly curve the airways (or worst), the bleeding may increase not letting you see anything and the airway may dis-align and the patient will lose it. 

In those cases, it is best to call for expert help at first, maybe a senior anesthetist and an ENT doctor, and you’ll have to use something that makes the patient unconscious and a bit relaxed, like propofol. Use it alone to tube the patient. You’ll need to make a very difficult intubation, the patient won’t be relaxed, the neck will be stiff (thanks to the collar and the muscles) and you cannot overdose on propofol due to the hypotension it gives. Be ready and good luck! 

We know those situations may sound strange, but we saw them all in person, and we can assure you, there is nothing scarier than losing a stable airway!

One more trick, if you tube the patient in the esophagus, you can decide to leave the tube there to guide your second attempt. Furthermore, if the patient is by any chance vomiting for whatsoever reason, you jam the suction tube right on the tube itself (the one in the esophagus), using it as a transient NGT to minimize the risk of aspiration. In the pharynx, there are only two holes: the esophagus and the trachea. If one is already blocked, the second tube should go in the right place.

We really hope this post is of some help!
See you next time…
Namasté!

References

1. Advanced Trauma Life Support: Student Course Manual. 10^th Ed. Chicago, IL: American College of Surgeons; 2018.
2. Pino RM, et al. Clinical Anesthesia Procedures of the Massachusetts General Hospital. 9^th Ed. Philadelphia, PA: Wolters Kluwer; 2016.
3. Casey JD, et al. Bag-Mask Ventilation during tracheal intubation of critically ill adults. N Engl J Med 2019;380:811-21.
4. Morgenstern J. PreVent: BVM during RSI (Casey 2019). First10EM. Published on April 1, 2019. Accessed on March 28, 2021. Available at https://first10em.com/prevent-trial/
5. Boffard KD. Manual of Definitive Surgical Trauma Care. 5^th Ed. Boca Raton, FL: CRC Press; 2019.

How to Cite This Post

Marrano E, Ferrari M, Bellio G. The Importance of Breathing Clean Air. Surgical Pizza. Published on May 29, 2021. Accessed on September 15, 2023. Available at [https://surgicalpizza.org/critical-care/the-importance-of-breathing-clean-air/].