Prehospital Academy Lesson 11.5
EMT: Basic Ventilatory Management
This lecture continues on in the airway series by discussing basic ventilatory management. Emergency medical care begins with ensuring an open airway. As we discussed in assessment, the ABC's of assessment are Airway, Breathing, and Circulation. Airway and breathing are two of the first things we're going to assess in a patient, particularly if the patient is unconscious or appears to not be moving. In such cases, one of the first things that we're going to do is to open the airway and assess breathing.
Positioning and Opening the Airway
When we go to open the airway, particularly in an unconscious patient, we want to make sure that we position that patient correctly. For this instance, we're going to talk about placing the patient in the supine position. The supine, or face-up position, allows us the opportunity to manage the airway and get a good visual inspection of the airway and assess breathing and circulation appropriately. When we move patients that are unconscious, we should move them as a whole. In other words, you should make sure that you take care to have one person at the head and at least one person on the body so that you roll them as a unit to make sure to not articulate muscles and joints and cause potential further damage, particularly if you suspect trauma and need to protect the spine.
The number one airway occlusion, or the thing that occludes the airway most frequently, is the tongue. As you see here in the side view, the tongue can slide back into the back of the oropharynx, occluding the airway, and is the most common airway obstruction. For opening the airway and assessing the airway, we're going to use one of two techniques: the head-tilt, chin-lift maneuver or the jaw-thrust maneuver.
Head-Tilt, Chin-Lift: This maneuver is for patients who have no suspected trauma or cervical spine injury. This is because it articulates the spine. To perform the head-tilt, chin-lift maneuver, you'll place one hand on the head of the patient with the other hands two fingers under the jaw, and you will tilt the head upward, allowing the tongue to be pulled forward and away from the oropharynx.
Jaw-Thrust: We're going to use this in patients that we suspect have cervical spine trauma or have some index of suspicion that there may be injuries present that could be exacerbated by articulating the spine. For the jaw-thrust maneuver, you're going to follow the steps below: kneel above the patient's head, place your palms on the cheekbones of the patient, and moving your fingers behind the angles of the lower jaw, collapsing your fingers into your palms, you're going to move the jaw upward. You can use your thumbs to help position the jaw. This will cause the mandible to move out and upward, thus lifting the tongue again out of the oropharynx. This process can be painful, so be mindful of that as you're practicing in lab or as you're performing this in the field as well.
Clearing the Airway
Occasionally, we may need to open the mouth to be able to inspect the airway. So even if the airway is open, the mouth may be closed, and we can't get a good assessment through visualization or may need to insert an airway adjunct. For opening the mouth, we use a scissor technique or a cross-finger technique. You're going to place your thumb on the lower teeth, the teeth of the mandible, and you're going to place your middle finger or index finger on the maxillary teeth, and then you're going to scissor your fingers apart. That will open the mouth. Be mindful if you're going to insert something into the patient's mouth, especially your fingers, because during events such as seizures, you can sustain injury.
Suctioning may be needed to remove foreign bodies, particularly liquid foreign bodies such as emesis or vomit, or blood or secretions from the airway. In order for a patient to adequately ventilate and subsequently oxygenate, that airway must remain patent. There are several types of suction devices you're likely going to run into in the field. Some will be battery-powered portable suction devices, some will be wall-mounted suction machines, such as in the ambulance or in the hospital bay, and then you may have manual suction machines. As far as the techniques for suctioning are concerned, there are a couple of numbers you want to keep in mind. Never suction the mouth or nose for more than 15 seconds at one time for adult patients. We're going to use 10 seconds for children and 5 seconds for infants. This is because excessive suctioning, particularly after the material has been removed, can lead to additional hypoxia by not allowing adequate gas exchange to occur.
Airway Adjuncts
We have additional airway tools that we use to maintain an open airway. The next two devices that we'll discuss focus solely on pulling the tongue away from the oropharynx to allow air to pass through and subsequently enter the lungs for gas exchange.
Oropharyngeal Airways (OPAs): These are rigid devices that go into the mouth and pull the tongue away from the back of the mouth, thus clearing the airway. They should only be used in an unresponsive patient without a gag reflex.
Nasopharyngeal Airways (NPAs): These are used in patients who are unresponsive or have an altered level of consciousness but still have an intact gag reflex and have an inability to maintain their own airway spontaneously. Unlike the OPA, the NPAs are inserted into the nare of the nose and pass through the nasopharynx into the oropharynx to allow passage of air.
Assisting Ventilations
When a patient is not ventilating adequately on their own, we may need to assist ventilations to ensure adequate tidal and minute volume for oxygen delivery. The tool of choice for EMS and medicine in general is the bag-valve mask (BVM). When using a BVM, you're going to want to squeeze the bag just enough to see the chest rise. Remember that tidal volume is only 500 mL for an adult patient, so squeeze the bag just enough to see the chest rise and you're only going to deliver 10 to 12 breaths per minute. Excessive ventilation can lead to significant complications, such as gastric insufflation or complications associated with increased intrathoracic pressure.
As a reminder, normal ventilation occurs through something called negative pressure ventilation. When we introduce positive pressure ventilation, we change those dynamics significantly. It's important that when we deliver breaths through positive pressure ventilation, we only ventilate at 10 to 12 breaths per minute and only supply enough air with each breath to see the chest rise and fall. This will help prevent complications such as gastric insufflation, which is when air is forced past the epiglottic opening into the esophagus and ultimately down into the stomach. This complication further increases the intrathoracic pressure by pushing the diaphragm upward from the abdominal cavity, further reducing cardiac output and leading to a significantly increased risk for emesis, further complicating your airway management.
Critical Thinking Questions
What are the key differences between the head-tilt, chin-lift maneuver and the jaw-thrust maneuver, and in what specific patient scenarios would you choose one over the other?
Describe the potential complications of improper suctioning technique and how you would mitigate them in a clinical setting.
Explain the physiological differences between negative pressure ventilation and positive pressure ventilation. What are the potential risks associated with positive pressure ventilation, and how can they be minimized?
You are treating an unconscious patient with an unknown mechanism of injury. What steps would you take to assess and manage their airway, and what adjuncts might you use?
What are the indications and contraindications for using an OPA versus an NPA? Describe a patient scenario where an NPA would be the more appropriate choice.