Published Nov 19, 2002
Heres a favorite one of the mdas likes to ask the new students.
How many newtons of pressure do you apply during cricoid pressure?
When I heard this question I said, Oh my god!! I am in trouble.
the SI unit of force. A force of one newton will accelerate a mass of one kilogram at the rate of one meter per second per second. The corresponding unit in the CGS system is the dyne; there are 105 dynes in one newton. In traditional English terms, one newton is about 0.224 809 pounds of force (lbf) or 7.233 01 poundals. The newton is also equal to about 0.101 972 kilograms of force (kgf) or kiloponds (kp). The newton is named for Isaac Newton (1642-1727), the British mathematician, physicist, and natural philosopher. He was the first person to understand clearly the relationship between force (F), mass (m), and acceleration (a) expressed by the formula F = ma.
I say 1 ought to do it, but AI bet there is some trick answer.
44 newtons is the acceptable amount of pressure. This equals 9.856 or pretty darn close to the 10 pounds we learned to use.
Good work!! You guys are on the ball!!! Craig of course the trick to this answer is that the new student would never know this answer to this question right off the bat w/o looking it up. It is their way of showing how much there is to learn. (as if we did not already know this) Lee
Is there really something to look up? Isn't the right answer "as many as it takes to open the airway"? Because the amount of pressure would vary on the size of the patient. And you do have to apply equal pressure to the back of the neck--right? kAVI
There actually is a right answer, it is 10 lbs or 44 newtons on average. There have been studies ( I can't pull them up right now) to show this is the average pressure needed to obstruct the esophagus without closing the airway.
The topic for todays concepts of anesthesia, is airway blockade, and intubation. So I asked my instructor this question, and she answered.
You really need to find something better to do withyour time. I laughed pretty hard.
Anyway, they were impressed I knew the answer thanks to you all.
So Craig what you are saying he/she did'nt know the answer? :)
I get that same type of answers when I ask off-beat questions.
Don't you have anything better to do with your time!!
I couldn't help it. I'm a research freak. I e-mailed some Paramedic and M.D. friends. Their universal response was along the lines of "do as much pressure as it takes to get the job done."
So I did a web search and received three completely different answers. I've included the URLs in case anyone wants to see the source.....
Nat. Registry EMS exam tipshttp://www.medtrng.com/emttips.htm
"Judging how much pressure to apply during Sellick's maneuver may be difficult. This exercise will help you to understand how much pressure is needed. Pinch your thumb and index finder together. Push on the bridge on your nose, or your partner's nose, until it hurts. Pressure applied during Sellick's maneuver is about equal to the pressure it takes to cause pain."
Society of Anesthesiologists page quotes Sellick himself...http://www.asahq.org/Newsletters/1999/09_99/sellick0999.html
Sellick's seminal paper shows lateral X-rays of the neck with the esophagus containing a latex tube full of contrast medium, and the effect of cricoid pressure is wonderfully demonstrated. "Cricoid pressure must be exerted by an assistant. Before induction, the cricoid is palpated and lightly held between the thumb and second finger; as anaesthesia begins, pressure is exerted on the cricoid cartilage mainly by the index finger. Even a conscious patient can tolerate moderate pressure without discomfort but as soon as consciousness is lost, firm pressure can be applied without obstruction of the patient's airway. Pressure is maintained until intubation and inflation of the cuff of the endotracheal tube is complete." The diagrams and photographs of this application of pressure are excellent. He goes on to echo the thoughts of Kite and Curry saying, "During cricoid pressure the lungs may be ventilated by intermittent positive pressure without risk of gastric distension."
Med. Univ South Carolina RSI page http://www.musc.edu/emergmed/RSI/rsi14.htm
"The procedure is best performed with the use of three fingers - the thumb, index, and middle fingers. The index is placed directly over the cricoid notch to facilitate location, while the thumb and middle fingers are placed to either side of the cricoid for stabilization. All three fingers hold the pressure equally. How much pressure to apply? This amount has been determined to be around 20 - 40 newtons 64,65, but I hardly see how this fact is helpful. It has been suggested that this equals that pressure which results in about 1/4 of the nail-bed blanching (reference not available - I was told this by a colleague at an airway seminar). However, Sellick's maneuver has been reported to cause airway obstruction in up to about 10% of cases 66 - due to excessive force occluding the trachea. Caution is urged! "
So it looks like WntrMute is right, depending on the source. Kavi
to close esophegus for rapid intubation so stomach contents don't come up and the pt doesn't aspirate.
I know what cricoid pressure/Sellick's maneuver is used for. I was responding to the original question/and updating my former post about how many Newtons of pressure you should apply when doing Sellick's maneuver. Am I missing something? Kavi;)
I does seem that you were confused. You say as much pressure as it takes to open the airway. Sellick's maneuver is to obstruct the esophagus. You also say you apply pressure to the back of the neck. Esophagus sits behind the trachea and is closed using 2 to 3 fingers on the cricoid cartilage, never seen anyone going for the back of the neck. I'm sure you just got it confused with some other maneuver. Cuz your other post on the subject seemed right on.
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