Managing the Obese Difficult Airway

We were prompted to write this piece after a great case in the SimWars competition at ACEM2011.  Out of respect for the competitors who were faced with a really difficult case, we won’t mention names or case details, except to say that critically ill obese patients with difficult airways are one of the hardest things you can be faced with in an Emergency Department, a simulation scenario, or in an exam, and there are some great tips that can get you out of trouble, or at least prevent you from digging a hole that you can’t dig your way out of.  Some of the techniques we talk about will be universally applicable to all of your ED intubations, obese or otherwise, but we’ll try to keep it focused on obese patients, as they are a special risk group.

Obesity is on the rise, so it’s a not a matter of if but when you will be faced with a critically ill, hypoxic, obese patient needing airway support.  Read on for some pearls that will save you from browning your underwear, and your patients from crashing out on you.

NB: This is a very long article, but we hope you’ll find it useful.  It’s full of links to the best online airway resources we’ve found, and we’ve tried to summarise it into a mnemonic that will be easy to remember.

BACKGROUND: Problems with obese airways

  • Increased soft tissue mass
    • The increased weight & volume of soft tissue can distort the airway in a supine obese patient, making visualization of vital structures harder.
    • This can also make “lifting up” on the laryngoscope handle harder, as there is more weight to lift.
  • Increased pressure on diaphragm
    • Obese abdomens prevent normal diaphragmatic excursion.  This effect is dramatically exacerbated when the patient is supine. This leads to lower tidal volumes in spontaneously breathing patients, faster desaturation once sedated/paralysed, and more difficult bag-valve-mask ventilation, as you are trying to force air into lungs that have a lot more weight beneath them, even with airway adjuncts such as NPA’s & OPA’s. The increased pressure required to bag these patients sometimes results in more air going down the oesophagus (as the “path of least resistance”), resulting in gastric inflation, which exerts more upward pressure on the diaphragm.  A dangerous downward spiral can result from this scenario.
  • Reduced “Safe Apnoea Time”
    • This is the time between rendering a patient apnoeic with an anaesthetic, and the time they start to desaturate.
    • This happens more quickly in obese patients due to the poor mechanics of their airway (mentioned above), and their increased     metabolic demands/oxygen consumption, as well as their underlying hypoxia-inducing pathology.

So when confronted with an obese patient who may require intubation, I’ve come up with the following strategies which you may find helpful as well as a mnemonic that will help you remember what to do when confronted with this challenging clinical situation.

Preamble: Delayed Sequence Intubation
You may not be familiar with one technique that we mention below, so-called “DSI” or Delayed Sequence Intubation. This involves the use of non-invasive ventilation for pre-oxygenation, +/- ketamine to allow the patient to tolerate the mask.  Scott Weingart at EMCrit has a great blog post on it here, so check it out before reading on.

THE MNEMONIC:
Remember with obese patients, build a BIG RAMPPPP

B: BUY TIME: Increase FiO2, NIV, Optimise Medical Rx
IINDICATION FOR INTUBATION: do you really need to do it & do it now?
G: GET HELP: Anaesthetics, ICU, ENT, Nurses, Orderlies
R: RAMP: Build a big ramp!
A: APNOEIC OXYGENATION: use nasal prongs to maintain diffusion of O2
M: MINIMAL DRUGS: local anaesthetic spray/neb, ketamine/ketofol +/- sux/roc
P: PRE-OXYGENATE WITH NIV
P: PARALYSIS – ONLY IF NEEDED
P: PLAN FOR FAILURE: Surgical airway kit by the bedside
P: POST INTUBATION CARE

B: BUY TIME
By increasing the FiO2 of the system you are using, facilitating the flow of air/oxygen into the patient, using NIV and optimizing medical treatment before intubation, you will buy yourself some time before needing to intubate (or before the sats start dropping once you start!). You don’t want to delay things if the sats and GCS are falling before your eyes and the patient is peri-arrest,  but by trying some of the techniques below, you may end up starting from a better position once the intubation is underway. Remember that there is always more that one way to skin a (fat) cat, so before rushing into the intubation process, ask yourself if any of the following will help:

  • A better position
    • Sit the patient as upright as you can, which will allow for better diaphragmatic excursion (as long as the BP is OK)
    • Nominate one staff member (orderlies are helpful for this) to keep the patient in the best position if the patient can’t manage it.
  • A better oxygenation system
    • Non-rebreather mask
    • Venturi mask
    • Humidified oxygen
    • Heliox (useful in airway obstruction with normal lungs)

    All of which supply air that is either higher FiO2, or easier to breathe than standard wall oxygen via a Hudson mask

  • Non-invasive ventilation
    • CPAP/BiPAP can bail you out of many potential airway nightmares.
    • It may be sufficient on its own to dispel the need for intubation.
    • It can pre-oxygenate for you while you are amassing resources.
    • Some patients however will deteriorate with NIV, either due to exhaustion, inability to move air out of their tired chest or             diseased lungs with PEEP applied, or confusion/combativeness so don’t use it as a last resort without planning what your next move is.
    • NB Higher FiO2 and increased pressure behind that O2 source can markedly improve pre-oxygenation. BUT: If you have not achived sats greater than 95% after 3 minutes, it’s likely that there is “shunt” happening. This means that alveoli are being ventilated but not perfused due to things like pneumonia or pulmonary oedema, resulting in right-left shunt of de-oxygenated blood. This can be partially overcome by augmenting airway pressure
    • If you don’t have a CPAP/BiPAP machine, you can use a BVM with a PEEP valve. 

     

  • Don’t Rush Into RSI/DSI: Consider different intubation methods
    • Awake Intubation
      Here are some great awake intubation resources from EMCrit:

      This approach removes the need for RSI/paralysis, and is often a safer option (in experienced hands) if available

    • Fibre-optic/Video Laryngoscope intubation
    • No intubation
      • Can the patient just be observed in HDU/ICU for now, with ongoing maximal medical management of their condition and be intubated later if needed?

 

I: INDICATION: DO YOU REALLY NEED TO DO THIS, NOW?
Before going ahead and intubating an obese or morbidly obese patient, you want to be sure you really need to do it, and that you need to do it now.
Of course anyone who is arrested or apneic needs to be intubated (but don’t interrupt your CPR for more than 10 seconds to do it!)
However you need to be aware that if you sedate and paralyse an obese patient who was breathing spontaneously, and you fail to achieve intubation, things can go from bad to worse much faster than they would with a patient with a normal BMI.
Being sure of your indication will do several things:

1)    It will give you a clear direction for proceeding & allow you to plan & be systematic in your approach.
2)    It will make you double check that you’ve exhausted all medical therapies that may delay or prevent intubation.
3)    It will give you something to write on the Coroners deposition if/when things don’t go well…

G: GET HELP
Like we said, this scenario is much harder and fraught with more hidden dangers than a standard intubation, so get experienced help if you have time.  NB: Getting too much help can lead to a “too many chiefs, not enough Indians scenario”, however we would always err on the side of having too many anaesthetists/intensivists/ENT surgeons around compared to having none.

Some notes on help:
“The road to hell is paved with assumptions”
Don’t assume just because someone has a title that they are capable of doing the harder aspects of their job. An “Anaesthetic/ICU Registrar” may have little or no difficult/obese airway experience. A locum general surgeon may have never done a surgical airway.  The ICU Consultant may really struggle with the cricothyroidotomy despite having done hundreds of tracheostomies.

There is no easy way to do this, but a polite way to check the credentials of a stranger is to ask something like “so, have you done one of these before?”
It demands a specific answer, and may come across as a bit of joke with an experienced colleague, which can lighten the mood, but it also gives them and you a face-saving “out”, and a chance to find more experienced help (time permitting). Believe me, coming from someone who hasn’t checked credentials in the past, and had it backfire on me, you will kick yourself if/when things go wrong…

“People function best in a familiar environment”.
When you invite a non-ED colleague down to help you, they may want equipment you don’t have, or expect certain resources/skills that aren’t available, or expect your nursing staff or you to do things they/you aren’t familiar or comfortable with.  If you have time, getting them to run through their plan quickly and finding out what their “bail out” or “last resort” options are.  This can ensure that you have “made the environment familiar for them”, with all of the equipment they need on hand, and will avoid any mid-procedure surprises. Often there is a compulsion to rush and “just get on with it”, but taking even 20-30 seconds to explain the plan to everyone in the room before the drugs go in can be a life-saver. It also ensures that everyone is “on the same page”, and allows the nurses to get their stuff ready too.

R: RAMP! RAMP! RAMP!
Like a ground sensor in a plane that was flying toward a mountain, shouting “PULL UP, PULL UP, PULL UP” at the pilots, Cliff Reid & I were shouting (under our breath) “RAMP, RAMP RAMP” at the SimWars competitors at ACEM2011!

So what is a ramp?
A ramp is something that you ride a skateboard, BMX or dirtbike off, right? Wrong. A ramp is what will save your obese patient who you are about to intubate. Of all of the points in this article, this is the most important. If you remember nothing else, remember RAMP, RAMP RAMP!!

Why build a ramp?
“Ramping” the patient, or getting them into the “ear to sternal notch” position (see photos below) has many benefits in the obese patient:
1)    Optimises upper airway patency & laryngoscopy view
2)    Facilitates mask ventilation.
3)    Extends the safe apnea period
4)    Shortens time needed with mask ventilation to return to normal oxygen saturation
5)    Following intubation, it improves the mechanics of ventilation.

How to make a ramp:
Placing SEVERAL pillows (usually about 4-5 pillows will suffice – good luck finding these in your average overcrowded ED), plus rolled blankets or rolled towels so they form a “ramp” at the head of the bed is ESSENTIAL in managing the obese patient’s airway. You don’t just want one pillow under their head/shoulders. As in the pictures, you want the shoulders, and often the torso raised off the bed, with the cervical spine flexed, and the atlanto-occipital joint extended.

We could’t find an obese model, so ironically enlisted the help of the skinniest Emergency Physician we know, Dr Will Sargent, to be our model (even more ironic as he runs a food blog called willeatsdotcom).  His anatomy highlights the position you want your obese patients to be in when you make your ramp. Click on the thumbnails to enlarge the images.

Here is our hastily constructed ramp. (NB It took our PCA/Orderly Harry under a minute to locate a huge bag of spare pillows).
IMG_1975

There is no definition of how high it should be, or the angle the ramp should be on.  The correct ramp shape/size is that which achieves the desired position. The advantage of using pillows, towels or blankets over pre-made foam wedges or inflatable ramps is that they are infinitely adjustable to the patient’s anatomy.

Ideally the patients body should be on a 30-45 degree angle, and their head should be 8-10cm forward. The position you are aiming for is the “ear to sternal notch” position.

IMG_1973

The ramp should be relatively flat on top, which will allow extension of the atlanto-occipital joint.  It is a more exaggerated form of the “sniffing the morning air” position, as the thoracic spine is also supported by the ramp and elevated off the bed.  In a correctly positioned ramp the patients face should be parallel to the ceiling. 
Avoid over-extending the head, as this will actually tighten the pharyngeal soft tissues, compressing the neck, and make laryngoscopy more difficult.
This position also makes bag-valve-mask ventilation easier as the abdominal contents will not be pushing upward against the diaphragm.

IMG_1974_ESN_final

Notice how Will’s face is parallel to the ceiling, and his ear is level with his sternal notch.

IMG_1976

Compare this to the traditional one pillow technique above.  You can see how Will’s atlanto-occipital joint is somewhat flexed, which will make laryngoscopy more difficult.  Bagging obese patients in this position is more difficult as their airway will be less patent, and their abdominal contents will be pushing up against their diaphragm.

IMG_1977

Care should also be taken to ensure the ramp doesn’t put the patients head out of your reach when you are standing at the head of the bed. So remember, once you elevate the head of the patient, unless you are very tall, you will need to be in a higher position to perform laryngoscopy.  To get around this problem you can either:
1)    Lower the bed
2)    Stand on a footstool

(Thanks to Megan our Med Student for being the laryngoscope handler)

IMG_1978

You can see how in the ramped position, the view when performing laryngoscopy is almost directly down to the larynx.

Here’s some images that highlight the ramp vs flat position with actual obese patients:

ramp1ramp2

Going back to the aviation analogy, anyone who tries to stop you ramping a non-spinally-injured obese patient prior to intubation, or just gets one little pillow out for you to “prop their head up with”, should be treated as a terrorist in the cockpit who is trying to hijack your plane and fly it into a mountain, and should be fought off with same zeal!

A: APNOEIC OXYGENATION
This is another pearl that we have been introduced to recently, and we strongly recommend you start doing this with your ED intubations, especially in the obese patient.

apnoeic_oxygenation

Apnoeic oxygenation is the application of high flow oxygen via nasal prongs (at 10-15L/minute if the prongs can handle it & not blow the tubing off the tap) during intubation.  The premise is that you will be blowing some oxygen into the lungs, which will diffuse into the bloodstream, and buy you some time before the sats start dropping.  It has been shown to lengthen the time to critical hypoxia, and shortens the time needed with mask ventilation to return to normal oxygen saturation.  It’s so obvious, I can’t believe we haven’t made this a routine part of ED intubations earlier.  Obviously nasal obstruction of any kind will hamper this technique, but for everyone else, there is no contraindication.

M: MINIMAL DRUGS
The moral of this section is: “CHOOSE YOUR DRUGS WISELY”.
Which drug you use to put your obese patient into a state in which they’ll tolerate intubation relates to experience/familiarity, institutional factors, and side-effect profile of the drug.  In general the goal is to achieve a state where the risk of hypoxia is minimized, and the chance of placing the tube 1st time are maximized.  Also, simplicity rules in these situations: the less things you need to get out, draw up and inject, the less room there is for error.

SEDATIVE
Some sort of sedative will be required, even for “awake” intubations. The choices are:

KETAMINE:
Pros:
Dissociative > sedative, at low to intermediate doses they keep breathing (usually), theoretically less aspiration risk (from preserved airway reflexes – which can hamper passage of tube – see “Spray the cords” – below), less/minimal hypotension.
Cons:
Preserved airway reflexes (ie risk of laryngospasm), psychogenic side effects (hallucinations/agitation), hypertension may result.

Contraindications to Ketamine as induction agent:
(NB: These differ slightly from the contraindications to using Ketamine as a procedural sedation agent)
Age < 12 months
Head Injury – controversial
Allergy
Psychosis
Uncontrolled seizure disorder
Congenital heart disease
Severe Hypertension
There are many relative CI’s, but none that carry as high a risk as using Propofol or Thipentone as an induction agent.

KETOFOL:
This a cocktail of ketamine and Propofol that you need to mix up yourself in a syringe.
You can get Scott Weingart’s Ketofol recipe here.  He recommends: 100mg of Propofol + 100mg of ketamine in one 20ml syringe = 5 mg/ml of each
NB: this halves the normal concentration of Propofol, to 5mg/ml (as opposed to the usual 10mg/ml)
Start with a dose of 10 ml (= 50mg Propofol  + 50 mg Ketamine) & titrate up until desired effect achieved.

Pros:
Added sedative effect without significantly increasing apnoea risk.
More likely to dampen airway reflexes than straight ketamine – may make tube passage through numbed cords easier.
Cons:
Increased apnoea/aspiration risk compared with straight ketamine
Dosing errors are easy to make: Be sure you mix up the ketamine correctly first, then add it to the Propofol.
Potentially increased risk of hypotension, however this will be less than with straight propofol.

PROPOFOL:
Anyone who hasn’t listened to Cliff Reid’s “Propofol Assassins” rant should do so before reading any further. It will make you think twice before picking up Michael Jackson’s Milk.  In it Cliff highlights the risks associated with this drug, and the potentially life threatening pitfalls you can experience while using it in critically ill patients.

Pros:
Excellent sedative. The patient won’t fight you while you’re trying to tube them
Cons:
The patient my not be fighting you because their MAP is so low they’re not perfusing their brain, and they may have unrecoverable hypotension.

FENTANYL & MIDAZOLAM
This is a good combination as they tend not to drop the blood pressure as much as Propofol, and they are both reversible if you suddenly need to wake the patient up (Fentanyl with Naloxone, Midazolam with Flumazenil).  If you’re not used to using Ketamine or Propofol, now is not the time to be experimenting, and familiar drugs like opiates and benzos are theoretically safer in less experienced hands.

Pros:
Rapid onset, amnesic, less hypotensive effect than Propofol, reversible/antidote available
Cons:
More respiratory depression than Ketamine.

LOCAL ANAESTHETIC SPRAY ON CORDS
This works on the premise that you are aware that you MAY NOT NEED TO PARALYSE THE PATIENT to get the tube in. How is this possible?
Cophenylcaine spray onto the cords, or 5mls of nebulized 1-2% lignocaine will dampen the afferent input from the cords.

Providing that the patient is at least partly sedated, not paralysed, and still spontaneously breathing, as you pass the tube and it touches the cords, you may see them “flinch” or oppose. This is where holding your nerve comes into it. If the cords don’t flinch, just pass the tube.  But if they do, DON’T PULL OUT! Sit there & keep watching, with the tip of the ETT just next to the cords.  The next time the patient inhales, the cords will open & voila, there is your James Bond moment to slip past the “numbed” guards and place the tube.
If this fails you may need to go ahead and paralyse the patient, but if it works, you have dodged a bullet, and made the process safer.

NB: We would recommend having a maximum of ONE attempt at this method, any more and you risk injuring the cords, and either causing paralysis of the cords or bruising/oedema/bleeding of the cords which can seriously hamper your next attempt at intubation.

Also, while this technique looks like a good idea on paper, doing it in reality is difficult with a sick, respiratory-compromised obese patient.  To nebulise the lignocaine, you need to stop whatever other inhaled treatment you have going on, and lower the O2 delivery to 6-8 litres/min.  Most CPAP/BiPAP machine allow you to put nebuliser in the circuit, so that’s another option.  To spray the cords, you need to be looking at them, which means laying the patient back on the ramp, with a laryngoscope in their mouth, and possibly 20-30mg of ketamine already on board to make them tolerate it. Pre-spraying the mouth/throat before you do this may make it easier for them to tolerate the laryngoscope.

P: PREOXYGENATE WITH NIV
Non-invasive ventilation allows ‘hands free” application of 100% oxygen, under pressure, to your spontaneously breathing, obese patient in respiratory distress.  It may provide enough FiO2 and flow to raise the sats before you proceed with intubation, or it may just stop them dropping any further.

In agitated patients, some people are advocating the use of ketamine to make the patient “tolerate” NIV (even if only for a few minutes) & giving it time to work. Again, this makes intuitive sense, but before you go ahead and give drugs to someone on NIV, remember:

1) They must be watched like a hawk. If they vomit with an NIV mask on after you’ve knocked them off a bit, they have a very high chance of dying without immediate removal of the mask, as they will be too blunted to remove it themselves.

2) Say what you like about ketamine being a “dissociative” agent, and not being a “sleepy” drug, but by giving ketamine you are giving someone in respiratory distress a sedative, which can make them breathe less, and their respiratory status may plummet soon after you give the drugs.  While the incidence of apnoea with ketamine is low, it is not zero. Also, they may just take shallower breaths, or fewer breaths per minute, resulting in worsening hypoxia, despite any diffusion that may occur.  So before you give the drugs, have everything else ready to go as if you’re going to intubate.

Scott Weingart from EMCrit advocates only a few minutes on NIV before intubating.  This seems logical, because if the sats aren’t coming up by the 3-5 minute mark, they are unlikely to come up if you wait longer.

The usual contraindications to NIV apply:
Apnea

Marked Hemodynamic instability

Inability to protect the airway: Low GCS, swallowing impaired, vomiting

Poor mask fit/Abnormal facial anatomy

Altered mental status: low GCS/combative/agitated/uncooperative
Inability to tolerate the mask
End-stage disease

NB There are other contraindications for prolonged/therapeutic NIV (eg diagnosis of pneumonia), but we’re just talking about using it for pre-oxygenation.

Here’s some other tips on Preoxygenation from Cliff Reid at Resus.me

P: PARALYSIS – ONLY IF NEEDED
Again the risk of paralysis needs to be weighed against the potential benefits. Paralysis makes the patient lie still, relaxes their jaw, which will make passage of the laryngoscope easier, and stops the cords closing when you touch them with the tube. The downside is you render the patient apneic, which means they can aspirate, and the sats will start dropping quickly.  (Remember, you can delay the onset of hypoxia by using the “apneic oxygenation” technique, and the aspiration risk will possibly be lowered by the ramp, +/- cricoid pressure.

Heard the cry “Sux Sucks! Rock Rocks!”?
People have varied opinions about whether or not to use any paralytic agent, and those that use them argue about which is the right one.
As to whether or not you should paralyse your obese patient prior to intubation, Scott Weingart has a great debate with Paul Mayo about use of paralytics in critical care intubations here.

Scott makes a strong case that overall, paralytic use is associated with more favourable intubating conditions, higher 1st pass success rates, and lower risk of complications. Also remember, the reason you are intubating this patient is because they need to be intubated! Even if you fail the intubation and decide to abort & let the drugs wear off, once the sedation/paralysis wears off in these patients, they are still as sick, if not sicker than when you started, and still need to be intubated, so you may as well do what you can to maximize your chances at success, first time around.

First pass intubation also matters because it has been shown that if you have more than 2 attempts at intubation, your risk of desaturation, hypotension and arrest go up dramatically. 

The counter argument is that “success and speed” shouldn’t be the end-points we look at, but rather maintenance of physiology.  Many of these patients are starting from a hypoxic/hypotensive position, and knocking off spontaneous respiration with paralytics means you may find yourself in a position where you can’t bag the patient (because of the difficulties mentioned above) and all of a sudden you have a patient who is suffering hypoxic brain injury on your hands.

This strategy (no paralytics) works well with specifically trained teams of staff, with checklists, an assigned vital signs watcher, post-case debriefing, ongoing QI including video-taping of every procedure & case review.  The focus on defense of physiologic function as opposed to “first pass success” has been shown to yield good results, and lowering of death rates, and similar rates of other complications when compared to giving paralytics.  The argument then is that if complication rates are similar (including failed intubation), then why use more drugs? Remember that for this approach to work you need INTENSIVE training, resources, and leadership, which most places don’t have.

The use of paralytics assumes that intubation will be successful, and that you’ll be able to bag the patient. This is not always certain, and is in fact a black hole that we launch into every time we give paralytics… Can’t intubate, Can’t Ventilate, is a bad, bad place to be, even worse when your patient weighs over 120kg, and can result in death or permanent neurological injury.

Paul makes the strong argument that RSI is a technique devised for the anaesthetists, for use with well, fasted, elective patients in an operating theatre, who can be hyper-oxygenated beforehand, where can you can just “let the drugs wear off’ if the intubation fails and the patient will return to their “well” pre-anaesthetic state. This is not the case with the sick, obese patients we are talking about, and hence RSI should not be used on them.

He mentions some lethal RSI assumptions that lead to deaths of patients:
“I never miss”
“I can BVM anybody”
“The K is normal”
“Anaesthetics does it!”
“My ED Consultant does it!”

The upshot of all of this to-ing and fro-ing is that if you:
    Don’t know how to use difficult airway equipment in obese patients
    Don’t know how to do a surgical airway in an obese patient
    Haven’t mastered your difficult airway algorithm
(in an obese patient)
Then you probably shouldn’t be intubating at all, paralytics or no paralytics…

If you want some “evidence” about Sux vs Roc, check out the Cochrane review.

For more on Sux vs Roc, check out Resus.me which has a nice video, and some good comments below it.

If you want to use a paralytic, whatever your choice of agent, you need to weigh risks/benefits of the individual drugs in your patient.

SUXAMTHONIUM:
Rapid onset, short duration
Wears off “quickly”, but often not quick enough to prevent severe hypoxia
Again –  risk is mitigated by preoxygenation and apneic oxygenation.
Contraindications:
Hyperkalaemia – check the K+ on a VBG before using
Known Malignant Hyperthermia
Pseudocholinesterase deficiency – prolonged apnoea
Potential side effects:
Hyperkalemia – check the K+ on a VBG before administering
Bradyarrhythmias
Masseter spasm
Increased intragastric, intraocular, and possibly intracranial pressure
Malignant hyperthermia
Histamine release

NON-DEPOLARISING: ROCURONIUM
Rocuronium seems to be the flavor of the month, and for good reason.
It has a faster onset time than Vecuronium, minimal histamine release and minimal cardiovascular effects.
1.2-1.4mg/kg has roughly the same onset time (a little bit slower) as suxamethonium.
It essentially has minimal/no side effects.  Probably the main one to watch for is anaphylaxis.

It is useful if Sux is contraindicated, but potentially fatal if you can’t intubate/can’t ventilate and stuff around before moving to a surgical airway.

If you’ve checked out the links above, you’ll see there are strong arguments for using either of these two drugs, depending on what you believe is the best for your patient.  We can’t recommend one vs the other, as we alter it depending on the .linical situation.  Our best is advice is be familiar with both, know the pitfalls for both, and know what do you if you can’t intubate/can’t ventilate after you give either of them.

P: PLAN FOR FAILURE
Remember that despite all of the above, you may still end up doing a needle or surgical cricothyroidotomy on this patient.  If you think that’s going to be easier than the intubation you just failed, think again.  Having the cric kit by the bedside is one thing.  As is doing a cric on an anesthetized greyhound at the EMST course. Knowing what’s in your kit (lots of them have many pieces), how to access it quickly, and how to get it inserted into an obese neck are just some of the challenges you will face. But if you’ve sought appropriate help in the beginning, you’ll hopefully have an intensivist (who’s used to doing tracheostomies), or an ENT surgeon standing by who will probably be better at it than you, so get them to do it!

One thing I’d suggest you practice is getting an unassembled Cric kit off a shelf, open, and assembled in under 20 seconds. Most ED’s have kits that have been opened for teaching purposes laying around in a box somewhere, so check what’s in your resus room, and practice putting the whole thing together as quickly as you can, so that when the crap hits the fan, you will know exactly what you’re doing, and how long its going to take.

Weighing up needle/seldinger vs surgical/scalpel cric in the obese patient, I think on the balance of things we’d recommend the needle/seldinger method. Neither is simple, and here’s some pros & cons of each method to help you decide what you’d like to do in this situation:

NEEDLE/SELDINGER:
Pros:
Possible easier to traverse the fat of the neck with a stiff needle (as long as you have it attached to a syringe with saline in it so you know when you’re in the airway – bubbles in the syringe)
Once the wire goes in, you know you have a path to the trachea
Cons:
May be hard to stabilize the trachea and “lance” it with the needle – may slip off to either side
It can be hard to slide the tube/dilator through the soft tissues without the wire kinking

SURGICAL/SCALPEL
Pros:
You are cutting a direct path to the trachea, and will either be able to see it or at least palpate it directly
Cons:
Blood & Fat.  Remember when you cut the skin, it bleeds. Fat tends to ooze back into wounds obscuring your view.
You may not be able to see where you’re going and may have to make the incision through the cricothyroid membrane “blind”, risking cutting in the wrong place, or possibly cutting yourself.

Here’s a great discussion on needle vs knife cric’s

Regarding “planning for failure”, in an outstanding piece of medical webucation, Cliff Reid & Scott Weingart team up to talk about “failure to plan for failure” with regard to airway disasters in this great post.

A key point is that according to the NAP-4 Audit of Major Complications of Airway Management in the UK (nicely summarised by Cliff Reid here). It was noted that obese patients feature prominently in airway disaster cases.

Therefore you must have a plan for CICVCO (Can’t Intubate, Can’t Ventilate, Can’t Oxygenate) situations.  This means a surgical airway.  If you’ve ever seen one of these done on a real patient, you’ll know it’s not nearly as easy as it looks on the videos, or on the mannequins at the various resus courses. Add a couple of inches of fat to it, and you’re multiplying the degree of difficulty ten-fold.

Hence our list of people on the “get help” list includes ENT surgeons.  These guys are used to cutting holes in people’s necks, and are invaluable in a surgical airway situation.  If you are preparing to intubate an obese patient, and are lucky enough to be in a hospital that has ENT backup, we can’t emphasise enough that.

My difficult airway routine goes like this:
Remove Cricoid pressure/BURP/manually manipulate larynx
Bougie
LMA (+/- Smaller tube)
Bailout/reoxygenate if able
Cricothyrotomy

Here’s another flowchart:
failure

From: Damage Control Anesthesia, Richard P. Dutton, International TraumaCare (ITACCS) Fall 2005

If you think a surgical airway is going to be easier than the intubation you just failed, think again.  Having the cric kit by the bedside is one thing.  As is doing a cric on an anesthetized greyhound at the EMST course. Knowing what’s in your kit (lots of them have many pieces), how to access it quickly, and how to get it inserted into an obese neck are just some of the challenges you will face. But if you’ve sought appropriate help in the beginning, you’ll hopefully have an intensivist (who’s used to doing tracheostomies), or an ENT surgeon standing by who will probably be better at it than you, so get them to do it!

One thing I’d suggest you practice is getting an unassembled Cric kit off a shelf, open, and assembled in under 20 seconds. Most ED’s have kits that have been opened for teaching purposes laying around in a box somewhere, so check what’s in your resusc room, and practice putting the whole thing together as quick
ly as you can, so that when the crap hits the fan, you will know exactly what you’re doing, and how long its going to take.

There are various ways to get a tube through the skin, into the trachea.  Here’s a few:

“Scalpel-finger-tube”

Bougie Assisted

A few more different techniques

Some more tips from EMCrit

If you need convincing to “Plan For Failure” read this post. Watch the Video. Download the pdf and read it. Chilling.

P: POST INTUBATION CARE
Remember that getting the tube in is just the start. Now you need to actually start providing intensive care for your patient! Some “basic” ventilators like the Oxylogs found in most Australian ED’s can struggle with ventilating obese patients with lung disease, who often have high pressures and poor lung mechanics. Some simple post intubation steps can help you with your ventilation while waiting to get to ICU:

Nasogastric – ASAP to deflate stomach
Ongoing analgesia/sedation/paralysis – prevents them “fighting the ventilator”
Maintain ramp: or tilt bed feet down
Suction the tube: to get any pus/fluid/blood out
Ongoing medical management: for example nebulisers, steroids and magnesium in asthmatics, antibiotics for infections, diuretics in APO     (controversial I know, but small doses are usually OK)
And most importantly: Get them onto the snazzy ICU ventilator!

CONCLUSION
So there you have it, a rather long article on managing the obese airway, but hopefully the mnemonic will help you next time you are faced with an obese patient who needs intubation. Remember to build a BIG RAMPPPP!

B: BUY TIME: Increase FiO2, NIV, Optimise Medical Rx
IINDICATION FOR INTUBATION: do you really need to do it & do it now?
G: GET HELP: Anaesthetics, ICU, ENT, Nurses, Orderlies
R: RAMP: Build a big ramp!
A: APNOEIC OXYGENATION: use nasal prongs to maintain diffusion of O2
M: MINIMAL DRUGS: local anaesthetic spray/neb, ketamine/ketofol +/- sux/roc
P: PRE-OXYGENATE WITH NIV
P: PARALYSIS – ONLY IF NEEDED
P: PLAN FOR FAILURE: Surgical airway kit by the bedside
P: POST INTUBATION CARE

For more on general airway management, check out the LITFL “Own The Airway” page.

ALSO: PRINT & CUT OUT OUR HANDY QUICK REFERENCE CARD!
Obese_Airway_Card

No comments yet.

Leave a Reply