Intubating a human being is one of the most butt puckering procedures one can be responsible for, particularly as a novice. There is something intensely intimidating about being the person at the head of the bed. All eyes on you, watching your technique. Everyone is acutely aware there is a time limited approach to this and the dreaded can’t intubate, can’t oxygenate (CICO) situation is the elephant in the room. What if you can’t get it in? What if no one can get it in? So we train and practice like pilots do - through didactics and simulations and developing strategies, practicing technique over and over. Learning how to assess for a difficult airway and predicting difficulty in order to plan for and mitigate risk. In this article I’ll make the case for why the scenario, or reason requiring intubation, is the most important factor of all. We’ll discuss the different diagnoses, what specific risks they carry, and what you can do to mitigate those risks before you even start.

The Hypoxic Patient

Whats the big deal?

• Hypoxia is one of the H’s and T’s of cardiac arrest etiology.

• If you assess that they could be a difficult intubation things could be delayed in the process. Low/no O2 in = worse hypoxia.

• The more attempts at intubation the longer they aren’t getting good FiO2.

What type of patients are at risk?

• The highest predictor of peri-intubation hypoxia is pre-intubation hypoxia.

• Common etiologies: ARDS, COVID-19, pneumonia, pulmonary edema, atelectasis, ILD, PE, COPD

What can you do about it?

• Preoxygenate. Use NC + BVM or CPAP. Shoot for SPO2 >95 before starting, if possible. Leave the NC on during intubation attempts.

• Aim for one pass success. Limit repeated attempts. Most skilled person intubates.

• Once you intubate and they continue to desat:

  • Are there equal bilateral breath sounds? Is the tube positioned correctly?

  • Be patient. Pulse ox lag is a real thing. Make sure you have a good waveform and connection site. Is it distal to your BP cuff which keeps going off?

  • Bag up your SPO2 to above 93 for 3 minutes to optimize before putting on the vent or attempting again if initial attempt failed.

  • Dial up that peep valve.

  • Will prone ventilation help?

  • Find optimum vent mode, APRV? Do they respond well to additional PEEP or not? Investigate recruitment strategies.

  • Is there a need for a bronchoscopy? Is there a need for diuresis or thoracentesis?

The Metabolic Acidosis Patient

What’s the big deal?

• What is the body’s way of trying to cope with metabolic acidosis? Yep, respiratory alkalosis. This looks like a person who is breathing heavy and fast - Kussmaul’s. This buffers the serum build up of acid by blowing of CO2. If that patient suddenly stops blowing off CO2 - either because they wore out or because we medicated it away (think: induction agents) a respiratory acidosis now compounds your metabolic acidosis = more acidosis -> cardiac arrest.

• These are the scariest people to intubate in my opinion.

What type of patients are at risk?

• Common etiologies: sepsis, DKA, renal failure, high lactic acid level (probably also in shock so double whammy), overdoses (anything that generates lactic acid: alcohol, methamphetamines).

What can you do about it?

• Avoid over sedating.

• Don’t give bicarb until after you’ve intubated. Bicarb breaks down into CO2 and water in the body. Therefore if this patient isn’t going to breathe enough to blow it off, you’ve maybe helped the metabolic acidosis but now created a respiratory acidosis.

• Use a continuous end tidal CO2 detector pre and peri-intubation. Get a feel for what your baseline number is before you take away their respiratory drive. If their ABG reflects full compensation you want to shoot for a post-intubation ventilation strategy that mimics what they are currently doing. If the CO2 starts to rise you know their compensation is going away and you need to breathe for them more (BVM, increase MV on vent, etc.) and consider bicarb at that point assuming you are breathing well for them.

• Once RSI given bag at a decent rate, at least 12 breaths per minute.

• Aim for first pass success. BVM in between attempts = unpredictible ventilation.

• Once tubed, set to a vent to a high respiratory rate/TV as tolerated to shoot for MV on the higher end (~10-12 depending on how bad the pH was).

The Hypotensive Patient

What’s the big deal?

• The drugs we give to sedate/paralyze take away sympathetic drive (so no more extra beta adrenergic activity like HR and BP).

• The positive pressure from the vent increases intra-thoracic pressures which reduces venous return (aka preload) which reduces blood pressure.

• These factors will compound the already present hypotension = codes.

Who is at risk?

• Anyone with low BP.

What can you do about it?

• Hang IV fluids + Levophed pre-intubation. Make completely sure you have excellent IV access.

• Have push dose pressors on hand, Neo pre-mixed syringe or make your own push dose Epi which is my preference. You can find instructions on that here.

• Choose induction agents that have the least negative inotrope properties (propofol/precedex are big offenders). Instead opt for Ketamine (which will likely induce a hyperdynamic effect instead) +/- versed and paralytic of choice.

• Once intubated keep airway pressures including PEEP as minimal as possible.

The Asthma Patient

Why is it bad?

• Their airway pressures are likely very high from air trapping.

• They probably also have a respiratory acidosis.

Who is at risk?

• Status asthmaticus.

What can you do about it?

• First pass intubation success (are you seeing a theme yet).

• Minimize bagging - don’t “overbag” these folks. And limit the amount of time you have to bag by pre-oxygenating via whatever they are currently on whether it is Bipap or NRB, etc.

• Ventilator strategy once tubed is an issue and must be very closely monitored by an astute clinician, we often cause iatrogenic harm in these folks. See the post here.

The GIB/Vomiting Patient

Why is it bad?

• Vomit. Need I say more? Lol, no but really. Vomit causes a whole host of problems when one is wanting to see down into an airway. Anything that instigates a gag is going to wreak havoc.

• If they vomit and obstruct your airway, no matter what device you use you can’t see the cords. And you’ll push some of that down the lungs and then they have pneumonitis.

Who is at risk?

• Patients with GIB.

What can you do about it?

• Place NGT to LIS and empty the stomach prior to intubation.

• Give an IV push of 10mg Reglan about 10m prior to intubating. It’s not for gastric motility, although that’s a bonus. It’s to raise the lower esophageal sphincter tone with helps keep whats in the stomach, in the stomach.

• If possible intubate with the pt as upright as possible.

• Do your pre intubation checks very thoroughly. You want to have an excellent source of suction. Have a back up yankeur and suction cannister. If your hospital has them, use a Ducanto or other large bore suction tool.

• Tank them up beforehand if you have the luxury of time. These folks are often in hemorrhagic shock. Do what you can to mitigate hypovolemia and potential hemodynamic collapse.

• Strongly recommend using a paralytic - gagging is your enemy here. Could consider Fentanyl to blunt coughing.

• Try like heck not to have to BVM if at all. A fair amount of air goes into the stomach when we bag. This would obviously be bad.

• Use whatever laryngoscope you want, but somewhere close by have a direct blade. Video assisted laryngoscopes tend to get obscured by emesis and/or then fog up.

references:

https://litfl.com/post-intubation-hypoxia/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6322012/