ULTRASOUND ZOOM
Airway Management with Point-of-CareUltrasound: A Breath of Fresh Air By Kristopher A. Hendershot, MD, PGY-2 University of Miami / Jackson Health System
EMS just alerted you that a cardiac arrest is en route. You now have three minutes to gather all your airway equipment. You call respiratory therapy, get your oxygen and suction set up, and grab your tube, blade, lube, and syringe. Just in case, you grab your GlideScope and bougie. Did you grab your ultrasound? Sure, you probably grabbed it to assess cardiac activity, but what about the airway? The patient is brought in with an endotracheal tube already in place. You go to listen for breath sounds but with all of the chaos around, the airway is difficult to assess with your stethoscope alone. Quite frankly, you cannot hear anything, and the EtCO2 will take a couple of minutes to get set up. Now consider another scenario. A young woman just had a first date at a Red Lobster and in trying to impress her date, ate some lobster even though she knows she is allergic. She comes into your critical care area with a large amount of angioedema, with stridor, hypotensive, and covered in hives. You order the anaphylaxis medications and while the nurse is grabbing the medications, you quickly grab an eleven blade, a boogie, and a 6.0 endotracheal tube because you have a sick feeling in your stomach telling you where this is headed. You start palpating the neck for landmarks and quite frankly, this is a disaster—she is female, has a short neck, is obese, and with all the swelling, you really have no idea what you are feeling. In both situations, what do you do? After reading this article, I hope you will grab your linear probe.
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Edited by Leila Posaw, MD, MPH
Emergency Ultrasound Faculty, Jackson Memorial Hospital
ENDOTRACHEAL INTUBATION POCUS can be utilized to determine correct tube position either by direct visualization of the tube in the trachea or esophagus or indirectly by assessing ventilation, either by detecting pleural sliding or diaphragmatic excursion. Esophageal intubations might occur as often as 15.3% of the time during emergency airway access.1 Traditionally, auscultation is the preferred method of excluding esophageal intubation but it takes time, increases the risk of aspiration, and is relatively unreliable.2 EtCO2 is the gold standard for confirming tube placement; however, this too can be unreliable, particularly in cardiac arrest when it is only 60% to 65% sensitive for identifying endotracheal intubations.3 One of the first studies to look at point-of-care ultrasound (POCUS) confirmation of tracheal intubation found that it was accurate 98.2% of the time with a kappa value of 0.93, which aligns highly with capnography confirmation.4 A large meta-analysis of seventeen studies and 1,595 patients showed that POCUS was 98.7% sensitive and 97.1% specific.1 A more recent meta-analysis with 30 studies and 2,534 patients showed that POCUS was 98.2% sensitive and 95.7% specific.5 A study conducted in the emergency department at a Level I trauma center showed that the dynamic POCUS approach took an average of 18.25 seconds to identify esophageal intubations compared to the 177.5 seconds that it took in the EMpulse Winter 2022
EtCO2 group.2
Tube Confirmation Method STEP 1: Place the linear probe in a transverse plane superior to the suprasternal notch to visualize the trachea (Fig. 1). The esophagus may appear as a thick five-layered structure usually on the left of the trachea. Note the thyroid lobes and isthmus. STEP 2: In a tracheal intubation you will see one air-mucosal interface with a comet-tail artifact and posterior shadowing. However, if the intubation is esophageal, you will see two air-mucosal interfaces (“double tract sign”) with the comettail artifact and posterior shadowing. This double tract sign has a sensitivity of 98% and specificity of 95% for esophageal intubation.2 STEP 3: Next, use the same probe to check the lungs bilaterally for lung sliding. Absence of lung sliding on the left indicates a right main stem intubation, and the tube will need to be pulled back (Fig. 2). HOT TIP: You can confirm the depth of the tube by placing saline or air into the tube balloon cuff. Now when scanning in the longitudinal plane, the tube may easily be visualized. Location of the balloon at the sternal notch correlates to the correct tube depth.
CRICOTHYROTOMY The standard method for identification of the cricothyroid membrane (CTM)
