At our larger, tertiary care, University Hospital, we have a “difficult airway team” with an experienced anesthesiologist with a surgeon for back-up available in the hospital 24-hours a day. At University Hospital East, we don’t have a difficult airway team in the hospital at night and the anesthesiologist and surgeon have to be called in from home when a difficult-to-intubate patient develops respiratory failure. In the operating room, the percentage of patients with a difficult airway is 1-4% but in the ICU or ER, it is as high as 20%. So what can the hospitalist or emergency room doctor do to ventilate the patient for the 20 minutes it takes before help arrives? 15 years ago… not much. But now, we have a lot of devices that we can use when an endotracheal tube cannot be placed. Here are some of the more common ones:
The video laryngoscope. One of the first of these to come to market was the Glidescope®. Similar devices include the McGrath, the King Vision®, the IntuBrite®, the APA™, the C-MAC®, and the Marshall Video Laryngoscope®. These laryngoscopes have largely replaced the rigid steel Macintosh and Miller laryngoscopes in many hospitals. They are easier to use and improve intubation success for less-experienced physicians. Many EMS units now carry them in their emergency squads. In our hospital, we have Glidscopes available in our ICU, OR, and ER. We still use standard laryngoscopes in our intubation kits that are in our crash carts but the respiratory therapists can get a Glidescope to the bedside on very short notice. They have been shown to double the likelihood of a successful intubation on the first pass of the endotracheal tube and can reduce the time of intubation to one-third the time it takes with a standard laryngoscope. Watch a video of how to use the Glidescope here.
The bougie. Think of this as a guide wire for an endotracheal tube. Many times, when looking at an airway with a laryngoscope, you can see part of the vocal cords but not enough to confidently pass an endotracheal tube. Or, you may be able to get a good look at the vocal cords but as soon as you introduce the endotracheal tube, you obliterate your view. The bougie can solve this problem by being being small and semi-rigid. Also, it is colored blue so it is easy to see the tip of it, even if the is a lot of blood, fluid, or floppy laryngeal tissues covering up the vocal cords. Once you pass the bougie into the trachea, you then simply slide an endotracheal tube over the bougie and into the airway. If you can’t slide an endotracheal tube over the bougie, you can put an adaptor on the end of it and at least blow oxygen through it. Watch a video of how to use a bougie to facilitate intubation here.
The laryngeal mask airway (LMA). These are very simple to insert and in fact, anesthesiologists will often use them during short duration surgeries to ventilate patients in the operating room. They require little skill to place and can ventilate patients sufficiently until you can get someone with advanced airway skills into the hospital to place an endotracheal tube. The LMA consists of an elliptical inflatable cuff that is inserted into the mouth (after lubricating it) and over the top of the tongue, along the hard palate until you meet resistance. You then inflate the cuff. In the middle of the cuff, is an opening that leads to the ventilation tube. When the cuff is inflated, it occludes the esophagus so that air coming out of the port can only go one way – down through the vocal cords into the trachea. They do need to be secured, particularly when transporting a patient, because if they migrate out of the mouth, air may not go into the trachea properly. Watch a video of insertion of an LMA here.
The Combitube. This is somewhat similar to the King airway (see below). It is a fool-proof tube that you place into the mouth so that it can either go into the esophagus or the trachea – it will usually go into the esophagus. Either way, you can ventilate the patient. Inside the Combitube, there are two tubes – one with an opening at the distal tip of the tube and one with an opening on the side of the tube about a third of the way back from the distal tip. There are two balloons on the Combitube – one at the tip and one about half way back from the tip. So, if the tube goes into the esophagus, then you blow both the proximal and the distal balloon up and ventilate through holes on the side of the Combitube. The distal balloon prevents air from going into the stomach and the proximal balloon prevents air from going back out of the mouth. If the Combitube ends up going into the trachea, then you can ventilate the patient through the distal tip of the tube. If you are not sure where the tube is, you can use an end-tidal CO2 detector connected to each of the two ports of the Combitube to determine if you are in the esophagus or the trachea. Watch a video of how to place a Combitube here.
The King airway. This looks a lot like a Combitube but it is designed to only go into the esophagus. Although there is a hole at the distal tip, it is only there in order to pass an NG/OG tube through it into the stomach and not designed to ventilate through it. Ventilation is through the side ports. Like the Combitube, the ventilation holes in the King airway are on the side of the tube, in between the two balloons. In a study of 27 emergency medical responders comparing the King airway to the Combitube, the King airway insertion time was 24 seconds and the Combitube insertion time was 38 seconds; the King airway was perceived by the responders to be easier to place and was preferred over the Combitube by 26/27 of the participants. Watch a video of how to place a King airway here.- The nasal intubation. OK, so this is not exactly a new device. This is an old-school approach that I was taught to use for difficult airways back in the early 80’s, before LMAs, King airways, and Glidescopes were invented. You simply liberally lubricate a small (#7 or #6) endotracheal tube and insert it into the nares like you would a nasogastric tube. A little neosynephrine in the nose will open things up and make passage of the tube easier. Once the endotracheal tube makes the curve in the back of the pharynx, you listen over the end of the tube (or, better yet, place an end-tidal CO2 monitor on the end of the tube). If you position the patient’s head in the “sniffing position” (as opposed to bending the neck forward like you would when inserting a nasogastric tube) then you will have more success getting the tube to go into the trachea instead of the esophagus. Insert following the breath sounds (or end-tidal CO2 waveform) until you are in the trachea. This is a particularly useful approach when you can’t open the patient’s mouth fully to insert an endotracheal tube orally and can also be useful in the patient with angioedema. Watch a video of how to place a nasotracheal tube here.
The whole idea of using any of these techniques is to be able to ventilate the patient as quickly as possible. So when should they be used in the hospital? First, if the physician is not trained or proficient in performing endotracheal intubation with a standard laryngoscope – there is just too much that can go wrong such as placing the endotracheal tube in the esophagus or causing airway trauma that can create difficulty even for the skilled operator who performs an attempt later. Second, if the physician cannot get the patient intubated quickly using a standard laryngoscope – my rule is that if it takes 3 tries, you need to go to another option. If all else fails, then the cricothyroidotomy is the procedure of last resort. The last time I did one of these was on a dog during an Advanced Trauma Life Support course in 1983 and I hope that I never have to do one again.
If you are on call by yourself in the hospital at night, make sure you know what is available because when you are responding to a cardiorespiratory arrest and you encounter a difficult airway, you’re not going to have time to go to a computer and search the internet for advice.
February 28, 2017
If that had happened to me, I would likely have severe anoxic brain injury. Yesterday, we had 4 patients in our ICU with severe anoxic brain damage that had been admitted after suffering cardiorespiratory arrests. But the patient who coded yesterday is waking up just fine this morning. So why do some patients get anoxic brain injury from prolonged hypoxemia and others seem to get by without any brain damage? I think it comes down to the wonders of 2,3-DPG.
This is particularly important in people who are traveling to high altitude (e.g., mountain climbers) and people who chronically are hypoxemic (e.g., patients with untreated sleep apnea). A normal person will have an oxygen saturation of nearly 100% as blood leaves the lungs; the red blood cells will release about 25% of its oxygen in the tissues so that the oxygen saturation is about 75% when that venous blood returns to the lungs. If you are at high altitude, your arterial blood’s oxygen saturation may only be 80% and if the red blood cells can only release oxygen down to a saturation of 75% as they pass through the tissues, then there isn’t much oxygen being released and the tissues can be starved for oxygen. 2,3-DPG allows the red blood cells to release oxygen down to a saturation that is much lower than 75%, say 60%, so that enough oxygen is being off-loaded into the tissues to keep them functioning normally. From a physiologic standpoint, we call this a “right shift of the oxyhemoglobin dissociation curve”.
One of my heroes is Lonnie Thompson. He is an OSU Professor of Earth Sciences. He is arguably one of the most renowned faculty members at the Ohio State University and his research involving high-altitude glacial ice core samples has led him to spend more time at extreme altitude than any other human in history. 2,3-DPG is one of the main reasons he can do it.
If blood was sent to the lab for a regular glucose check, this would require a full blood tube (another 5 ml). In 2014, the FDA approved one brand of glucometer, the Nova StatStrip Glucose Hospital Meter System, to be used on venous or arterial blood in critically ill patients. This is now the glucometer that we use in our ICU. It permits nurses to just draw up less than 1 ml of blood to put in the point-of-care glucometer (rather than filling up a blood tube to go to the lab) and this has greatly cut down on wasted blood.