I already mentioned, in More Bad Airway Instruction, the lack of utility of an age-based formula for calculating ETT (EndoTracheal Tube) size in children. Length-based sizing is more accurate. But what about weight?
As the body becomes larger, the amount of circulation needed to manage the metabolism of that person is increased, although the increased metabolic demands do not generally lead to weight loss, just a feeling of greater hunger.
The stroke volume (the amount of blood the heart squeezes out with each beat) will often increase to maintain circulation as the weight increases. The HR (Heart Rate) often will slow down as the cardiac output seems to be better managed by the increased stroke volume, instead of an increased HR. To accommodate this the blood vessels increase in diameter and the heart increases in size and wall thickness. Similar changes occur in the respiratory tract. A rule of thumb is that the HR for mammals is approximately five times the RR (Respiratory Rate).
A HR of 60 is expected to have a RR of about 12. 80 HR is about 16 RR. 100 HR is about 20 RR. This can be useful for locating a problem with one of the systems when the numbers are way out of line, such as HR 100, but RR of 40.
Anyway, the point of this is that, as the population is growing, who is carrying larger ETTs to manage the larger airways?
Do you just put a CombiTube in if the 10.0 mm ETT does not allow for a good seal of the cuff on the trachea?
Do you carry extra-large ETTs, such as 11.0 mm, 12.0 mm, 13.0 mm?
Do you put a couple of 6.0 mm ETTs in together and inflate the cuffs to try to almost get a seal?
Is there even much benefit from carrying most of the adult ETTs we tend to carry? 2 each (or more) of 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0 mm, 9.5 mm in some places is not unusual.
What difference does the extra 0.5 mm make in the emergent patient?
What difference does the extra 1.0 mm make in the emergent patient?
What if we carried a couple each of 6.0 mm, 8.0 mm, 10.0 mm, and 12.0 mm?
Certainly the cuff is more than capable of expanding to create a good seal if it is close to the right size. If it is not providing a seal, then the next larger tube should easily fit. The difference in airflow is something that can be made up with a slightly faster ventilation rate without having a big effect on CO2, (carbon dioxide) levels.
This doesn’t even get into the problem of over a half dozen different adult laryngoscope blades that are usually poorly designed and not appropriate for those who intubate infrequently or are still learning.
Maybe you don’t have 500+ pound patients who need intubation. Maybe you do, but feel that as long as the ETT is secured properly, everything is OK. This patient surely does not need any kind of good cuff seal to discourage aspiration of stomach contents. If the patient had GERD (GastroEsophageal Reflux Disease) while alive, perhaps a cardiac arrest improved the ability of peristalsis to prevent stomach contents from traveling to the mouth and trachea؟ The glass stomach is half full approach to airway management might be more appropriate.
As long as the patient is not likely to have eaten chili, pizza, beer, and other airway improving foods, this is not a problem. Unfortunately, it seems that patients desire these for a last meal. Not that these patients don’t eat them at other times. It just seems that they take special care to get an extra helping of these when they are preparing to meet EMS.
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Beer and pizza before meeting EMS? that never happens. At least to me. Mine always eat taco bell or lots and lots of collard greens. What I wouldn’t give for a larger tube than a 9 sometimes. What blade do you recommend for your 500lb pt that needs to be tubed? I still go for my 4 miller because I have had trouble squeezing a grand-view blade in along with their giant tongue. Any suggestions?
Trouble with the Grandview surprises me. You are not the first person I have heard this from.It seems to me that a flat wide blade will do a better job of moving things out of the way.One of the bigger problems with the plus size crowd is proper positioning. Take a little extra time to put something under the shoulders and line things up so that you are not wrestling with the weight of the head. Then it should be easier to manipulate the tongue.I will probably do a post on blades, but I am not a fan of the Miller/Flagg/Wisconsin blades that are most commonly available.The most important thing of airway management – use what works. It doesn’t have to be a tube if you are ventilating appropriately, even if you use RSI. The goal is ventilation, not intubation. People who do not get that do not have opinions worth listening to, no matter what letters they have after their name.
And what are the chances of an obese patient having eaten something recently anyway. (end sarcasm)