POTD: Intubating the Pregnant Patient

Intubating a pregnant woman is intimidating because you have two patients to consider. Physiologic changes in pregnancy can affect intubation so it is important to plan ahead.

Both ventilation and acid-base status change during pregnancy. As progesterone rises, there is an increase in tidal volume, which results in maternal respiratory alkalosis. This creates a gas gradient to allow for the transfer of CO2 from the fetus to the mom. This maternal hypocarbia causes uteroplacental vasoconstriction, which can cause fetal hypoperfusion and hypoxia. This creates a very delicate acid-base balance that is exacerbated by increased fetal oxygen consumption and CO2 production in the third trimester. In addition, the diaphragm is pushed up by the gravid uterus reducing the mother's functional residual capacity by 10-25%. As a result of these factors, pregnant patients have a shorter safe apnea time and can desaturate quickly.

Progesterone also decreases the tone of the lower esophageal sphincter. Combined with increased intraabdominal pressure from the gravid uterus, pregnant patients are at higher risk for aspiration. For these reasons, you should be careful with bagging and consider intubating in a semi-upright position. This position also has the benefit of taking some pressure off of the patient's chest and IVC.

Anticipate a difficult airway in pregnant patients. Failed intubation is 8x more likely than in the general population. Human placental growth hormone secreted in pregnancy increases blood flow to the upper airways. This results in edema and hyperemia of the airway, causing it to be smaller and more friable. For this reason, you should prepare a smaller caliber ETT. Rocuronium and succinylcholine have been studied with similar efficacy. Induction agents therefore depend on patient specific factors.

TLDR: 1. preoxygenate well due to shorter safe apnea time. 2. Consider a smaller ETT for a narrower and more friable airway. 3. Limit aspiration risks by decreasing bagging if possible 4. consider intubating patients in a semi-upright position.

Thanks for reading! 

Ariella

References: 

https://rebelem.com/respiratory-failure-and-airway-management-in-the-pregnant-patient/

https://www.nuemblog.com/blog/intubating-the-pregnant-patient

https://www.uptodate.com/contents/airway-management-for-the-pregnant-patient

The Double Set-up

Hi all,

This is going to be a short but important POTD!

I wanted to write about an airway set up technique, colloquially termed “The Double Set Up” that the trauma and northside teams used yesterday during a level 1 trauma.

Without giving any secrets away for a case that will likely be an M&M in the future, for some situational background, the patient was getting progressively hypoxic with vomitus covering the entire airway. It was hard to get visualization of the airway using the Glidescope. The airway options were clear: either tube via DL or crich.

The team smartly employed the double set up technique to secure the airway. 

What does this term mean?

The double set up is when you have simultaneously set up for an orotracheal intubation and for a cricothyroidotomy. The EM/ anesthesia physician is at the head of the bed with the orotracheal airway equipment, while the surgeon is completely prepared for the crich with the scalpel in hand at the neck of the patient. The neck should already be prepped, and the landmarks should be identified.

When should we do the double set up?

Strayer has an amazing blog post about this (see below). Here are some indications where you might want to do the double set-up:

• An unstable maxillofacial trauma patient

• As a last ditch effort to secure the orotracheal tube after a failed attempt

• Rapidly desaturating patient with challenging anatomical features / cannot be successfully bagged

• Concern for an obstructed airway

If the intubator is ultimately unsuccessful, they indicate to the surgical airway physician to proceed. If the orotracheal intubator is successful, then the surgical airway physician can stop.

References:

• Check out Strayer’s excellent post on this: https://emupdates.com/the-emergency-department-double-setup/ 

• https://www.emed.theclinics.com/article/S0733-8627(17)30075-5/pdf 

• http://maryland.ccproject.com/wp-content/uploads/sites/8/2015/09/Leeuwenberg-2015-Airway-Management-of-the-Critically-Ill-Patient-Modifications-of-Traditional-Rapid-Sequence-Induction-and-Intubation.pdf
  

Intubation Modalities

Which intubation modality should I choose?

There are more options to intubate a patient besides our standard RSI techniques. I’ll be giving a brief overview of some other options below & an excellent flowchart from WJEM. Since this is a POTD, I will not be going in depth into each modality. However, I’ll try and include major indications & pitfalls when going through them.

Delayed Sequence Intubation (DSI): Primarily used in patients who are preventing you from oxygenating them (i.e. pulling off their bipap, agitated etc…). This is basically procedural sedation where the “procedure” is preoxygenation. 

Begin by giving a dissociative dose of IV Ketamine (1-2 mg/kg) and once the patient is properly sedated, preoxygenate them as you wish. Ketamine usually preserves their respiratory drive, but you may need to step in and intubate earlier than you anticipate if the patient were to experience respiratory depression. When the patient is adequately preoxygenated, you can give the paralytic and intubate the patient as you normally would. 

Sometimes, just forcing the patient to tolerate Bipap without interruption may result in the patient’s respiratory status improving and avoiding intubation. 

Ketamine Only Breathing Intubation (KOBI): KOBI is a great choice in physiologically challenging intubations where patients cannot tolerate a moment of apnea such severe acidosis. 

Begin by giving a dissociative dose of IV Ketamine. The patient will then be sedated, but still breathing. Then proceed with your intubation modality of choice. Beware, the patient may be a little rigid, have a higher risk of vomiting, and the vocal cords will still be moving. Either the vocal cords can be “timed” or a paralytic given shortly before passing the endotracheal tube. Even if a paralytic is not used, it should be readily available incase of complications such as jaw rigidity. 

Awake Intubation: Awake intubations are the ideal choice for cooperative patients that may be difficult intubations, but the intubation is less urgent. The advantage lies in that it is incredibly safe (the patient is breathing the whole time) and the procedure can be aborted if the intubation cannot be completed. An example could be a patient with Ludwig’s angina, where the loss of airway reflexes in RSI could lead to dire consequences if the patient is unable to be intubated. It would likely be difficult to oxygenate & ventilate a patient with Ludwig's angina, especially with all the soft tissue collapse after induction & paralysis in RSI, leading to disastrous consequences. 

Begin by drying out the oropharynx (gauze, glyopyrrolate). Then, the goal will be to topicalize extensively. 4% Nebulized lidocaine should be used. Atomized lidocaine should also be given via the nose and mouth (usually in awake intubations, nasotracheal intubation via fiberoptic bronchoscope is better tolerated than orotracheal intubation). Lastly, the patient can also gargle viscous lidocaine. The patient can also be given anxiolysis (such as versed) and may need soft restraints depending on the clinical scenario. Proceed with either orotracheal or nasotracheal intubation. Once you have passed the cords, the patient can be fully sedated since the airway is then secured. 

https://emcrit.org/dsi/

https://emupdates.com/kobi/

Merelman, A. H, Perlmutter, M. C, & Strayer, R. J. (2019). Alternatives to Rapid Sequence Intubation: Contemporary Airway Management with Ketamine. Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health, 20(3). http://dx.doi.org/10.5811/westjem.2019.4.42753 Retrieved from https://escholarship.org/uc/item/4b27s3ks

https://www.emdocs.net/awake-endotracheal-intubation/