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Quite a bit has been written in the anesthesia literature about the unreliability of the Mallampati score as an indicator of the difficulty of intubation, and I had an interesting airway situation in the OR yesterday that illustrated it perfectly.
A 36 year old healthy male was coming in for vocal cord injections by ENT. These are cool cases because we'll (anesthesia) put the patient to sleep and then without securing the airway, turn the OR table so that the ENT surgeon has the airway. They'll place a rigid scope so that they can visualize the glottis, and the scope provides a channel for them to work through and for us to jet ventilate through. Usually we'll keep the patient relaxed with a sux drip, which is always fun.
I always look these patients up the day before because often they have complicated histories, and often they've been here before for these procedures and it can be very helpful to see how they were done previously. When I found this guys chart, I saw he had NOT had this procedure done before. He was 85kg and healthy. I did see that he'd had a hemithyroidectomy about a year and a half ago. Purely out of curiosity I decided to see if I could access his anesthesia record from that case (I should do that commonly, but I often don't). According to the anesthesia record, the patient was classified as a MP1 prior to induction, yet the CRNA had been unable to visualize the cords via DL and had only a grade 3 view with VL. Interesting, I thought. Probably was just a lazy MP evaluation and his airway was obscured by a goiter (hence needing the thyroid removal), which is gone now, so he'll be easy.
So I go see the patient in pre-op. Sure enough, he looks healthy and normal. MP is, in fact, a 1. He does have a slightly short TMD but not dramatic. Able to bite his upper lip, good neck and jaw ROM. He also has a short beard but nothing that will make him hard to mask. I did decide to have VL in the room, though I did not expect to need it.
So now we are in the OR. Put the monitors on, pre-oxygenate, start the propofol drip + give him a bolus of propofol, and mask him. First, he's hard to mask. Not real hard, but harder than I expected. Start the sux drip and give a bolus of sux. Still hard. Hmm. Oh well. Turn the table, now I'm masking him from below and he's still hard to hold a seal on, though I am getting good air exchange. Remove the mask so ENT can instrument the airway.....and they can't visualize the glottis. It took almost 15 minutes of them re-positioning their scope and eventually going down 2 sizes before they could get a decent view. Almost unheard of in a healthy, normal-looking patient for ENT to have such trouble. He jetted fine and the rest of the procedure was uneventful.
This is not the first time I've been surprised at the difficulty of DL on a given patient, but certainly it was the first time that the degree of difficulty was so dramatically different from what I expected. This was a young, healthy guy with perfectly normal-looking anatomy, who would have presented a real problem to me if I'd ever had to RSI him in the field.
Moral of the story: place very little faith in your assessment of airway difficulty. The assessments are still worth doing, because they are quick and easy and can alert you to obvious issues. But they are very insensitive tests....never ever assume an airway will not be difficult just because the patient "looks fine".
A 36 year old healthy male was coming in for vocal cord injections by ENT. These are cool cases because we'll (anesthesia) put the patient to sleep and then without securing the airway, turn the OR table so that the ENT surgeon has the airway. They'll place a rigid scope so that they can visualize the glottis, and the scope provides a channel for them to work through and for us to jet ventilate through. Usually we'll keep the patient relaxed with a sux drip, which is always fun.
I always look these patients up the day before because often they have complicated histories, and often they've been here before for these procedures and it can be very helpful to see how they were done previously. When I found this guys chart, I saw he had NOT had this procedure done before. He was 85kg and healthy. I did see that he'd had a hemithyroidectomy about a year and a half ago. Purely out of curiosity I decided to see if I could access his anesthesia record from that case (I should do that commonly, but I often don't). According to the anesthesia record, the patient was classified as a MP1 prior to induction, yet the CRNA had been unable to visualize the cords via DL and had only a grade 3 view with VL. Interesting, I thought. Probably was just a lazy MP evaluation and his airway was obscured by a goiter (hence needing the thyroid removal), which is gone now, so he'll be easy.
So I go see the patient in pre-op. Sure enough, he looks healthy and normal. MP is, in fact, a 1. He does have a slightly short TMD but not dramatic. Able to bite his upper lip, good neck and jaw ROM. He also has a short beard but nothing that will make him hard to mask. I did decide to have VL in the room, though I did not expect to need it.
So now we are in the OR. Put the monitors on, pre-oxygenate, start the propofol drip + give him a bolus of propofol, and mask him. First, he's hard to mask. Not real hard, but harder than I expected. Start the sux drip and give a bolus of sux. Still hard. Hmm. Oh well. Turn the table, now I'm masking him from below and he's still hard to hold a seal on, though I am getting good air exchange. Remove the mask so ENT can instrument the airway.....and they can't visualize the glottis. It took almost 15 minutes of them re-positioning their scope and eventually going down 2 sizes before they could get a decent view. Almost unheard of in a healthy, normal-looking patient for ENT to have such trouble. He jetted fine and the rest of the procedure was uneventful.
This is not the first time I've been surprised at the difficulty of DL on a given patient, but certainly it was the first time that the degree of difficulty was so dramatically different from what I expected. This was a young, healthy guy with perfectly normal-looking anatomy, who would have presented a real problem to me if I'd ever had to RSI him in the field.
Moral of the story: place very little faith in your assessment of airway difficulty. The assessments are still worth doing, because they are quick and easy and can alert you to obvious issues. But they are very insensitive tests....never ever assume an airway will not be difficult just because the patient "looks fine".
