POTD: Auricular Lacerations

The external ear, also known as the auricle or pinna, has unique anatomical features that influence wound management in this area. For today’s POTD, I’m going to review the anatomy of the outer ear and the management of auricular lacerations.

Anatomy

The term “outer ear” specifically refers to the auricle (or pinna) and the external auditory canal. The auricle can be divided into six sub-units: the helix, antihelix, conch, tragus, anti-tragus, and the lobule.

All of these structures, except the lobule, are composed of thick avascular cartilage that supports the ear’s shape and structure. This cartilage is surrounded by a poorly vascularized perichondrium, which is then covered by a tightly adherent connective tissue and skin layer.

Auricular Lacerations

When the ear sustains a laceration, it should be repaired using primary closure, similar to any other laceration. Simple lacerations (involving only the skin) or complex lacerations (exposing or extending through the cartilage layer) can be repaired by us ER doctors. However, for more advanced lacerations such as split earlobes, avulsions, or lacerations extending into the external auditory canal, an evaluation by an ENT or plastic surgeon is recommended.

Auricular Nerve Block

The ear is innervated by several nerves, including the auriculotemporal nerve, greater auricular nerve, lesser occipital nerve, and the vagus nerve. An auricular nerve block can be performed to anesthetize all areas of the ear except the conch (which is innervated by the vagus nerve).

• Draw up 10-20 ml of lidocaine without epi and attach a small 25g or 27g needle. (Remember the max dose of lido without epi is 7 mg/kg or 0.7 ml/kg)

• Enter skin at the point just below the ear, advance the needle posteriorly along the skin over the mastoid bone behind the ear, and inject 3-5 ml while withdrawing the needle

• Once the needle is close to the original puncture site, don’t remove it but redirect it anterior to the ear and inject another 3-5 ml while withdrawing the needle fully out of the skin

• Repeat the same process entering from above the ear.

• Enter skin at the point just above the ear, advance the needle posteriorly, inject 3-5 ml while withdrawing the needle, redirect the needle anteriorly and inject another 3-5 mL in front of the ear while withdrawing the needle.

Laceration Repair

Once the ear is anesthetized, irrigate the wound and assess for any exposed cartilage.

If there’s no exposed cartilage, repair the skin with 6-0 non-absorbable sutures using a standard simple interrupted technique.

If there’s exposed cartilage, you can still repair the wound with 5-0 or 6-0 non-absorbable sutures. However, you must ensure the skin is well-approximated and fully covers the cartilage. This might require the use of deep 5-0 absorbable sutures if the wound is full-thickness (through and through) or irregular.

Dressing

After the ear has been repaired, it is recommended to apply a bulky pressure dressing to avoid the dreaded cauliflower ear. Cauliflower ear is a deformity of the ear that arises when normal healthy ear cartilage is replaced by fibrocartilage. This occurs when the cartilage is left exposed or it suffers pressure necrosis from a hematoma forming between the skin and cartilage (as shown in the image below).

Head Wrap Technique: Apply petroleum gauze around the wound and pack it into the helix. Apply a generous amount of dry gauze anterior and posterior to the ear. Compress this dressing tightly to the head with kerlix gauze.  

Bolster Technique: Sandwich the wounded area between cotton rolls or small rolls of gauze, securing these in place by suturing them to the ear.

Ear Splint technique: Wet a small amount of plaster and coat it with a thin layer of cotton webril dressing to create a splint. Firmly press the splint in place against the ear with a wad of gauze. Cover the ear with several layers of gauze. Secure the splint to the head with a kerlix wrap around the head.
Review the steps here: https://www.aliem.com/trick-of-trade-splinting-ear/

Quick Caveat: Some argue that auricular hematomas are rare, and a pressure dressing can hinder wound healing through vascular compromise.

Antibiotics

As with any wound, ensure the patient’s tetanus status and administer an updated tetanus vaccine if necessary.

Historically, prophylactic antibiotics were commonly prescribed for ear lacerations. Evidence now suggests that they may not be universally required. The consensus among medical professionals, including UpToDate and multiple emergency medicine blogs, is that antibiotics (such as Augmentin or clindamycin) should be prescribed if the wound is visibly contaminated, if cartilage is exposed or requires repair, or if the patient is immunocompromised to increase their risk for infection.

Follow-Up

Technically speaking the best practice is to recommend the patient return in 24 hours to assess the wound for the development of an auricular hematoma. After this initial assessment, they should return in 4-5 days for suture removal.

 Sources:

https://accessmedicine.mhmedical.com/content.aspx?bookid=2969&sectionid=250461381

https://www.uptodate.com/contents/assessment-and-management-of-auricle-ear-lacerations

https://wikem.org/wiki/Ear_laceration

POTD: Insulin in the ER

Today’s POTD is brought to you by the fear and terror I feel every time I have to order insulin, so below I’m going to review the different types of insulin, when to use them, and importantly how to order them. 

Types of Insulin

There are four main classes of insulin: rapid-acting, short-acting, intermediate-acting, and long-acting. These classes are aptly named based on their onset time. Here is a summary of each class:

I know what you’re thinking – wow, that is a lot of options… which one do I chose?! How much do I give?! Do I give it subcutaneously or intravenously?! Well, luckily, the Maimo pharmacists simplified things for us by only having three types of insulin (lispro, glargine, and regular) and very thorough order sets. If you know your indication, SCM guides you through the rest.

Insulin administration comes in two flavors: subcutaneous and intravenous. Subcutaneous is the only dosage route for long-acting insulin but rapid and short-acting insulin can be given subcutaneous or intravenous. IV insulin should only be used when you are treating hyperkalemia, DKA or HHS. Otherwise, you should give insulin subq.

Dosage of insulin depends on the patient’s weight, blood glucose level, and insulin tolerance. This can be a lot to remember, so your best bet is to follow the order sets that I’ll go through next.

 Acute Hyperglycemia (without evidence of DKA or HHS) can be managed with subq lispro (as well as IV fluids and addressing the underlying cause). The amount of insulin you give depends on the patient’s current glucose level and their sensitivity or resistance to insulin. Be sure to ask what their home insulin regimen is before ordering. Then you can easily order through the “Insulin Subcutaneous Ordering” order set.

• Search for and open the order set “Insulin Subcutaneous Ordering”

• Select the patients feeding status – eating, tube feeding or NPO

• Scroll down to the “correction scale insulins” section and decide between very low dose, low dose, moderate dose, or high dose based on your patient’s home insulin regimen

  • Very low dose = for patients who are insulin naïve

  • Low dose = for patients who require less than 40 units per day

  • Moderate dose = for patients who require 40-80 units per day

  • High dose = for patients who require more than 80 units per day 

• Check the “insulin lispro correction scale injectable” under the appropriate dosing regimen. If you want to give a one-time dose in the ED double click the order to change the frequency from “3x/day, before meals” to “once” and make the start time “STAT”

DKA or HHS is treated with an IV infusion of regular insulin. We start the drip at 0.1 units/kg/hour and continue until the gap is closed. You may precede the drip with a bolus of IV lispro at 0.1 units/kg, but there is no evidence that giving a bolus is beneficial, and it can potentially cause hypoglycemia. Once the gap is closed, you can transition your patient to subq insulin by calculating the total amount of insulin administered IV and then give 50% of that total as subq glargine insulin.  (Of course, there are many other aspects of DKA/HHS management which could be a separate POTD; I’m just highlighting some key points here.)

• Search for and open the order set “ED DKA/HHS Ordering”

• Scroll down to “insulin” and check the “insulin 100 units in NS 100ml” infusion. You will need to double click the order to input a dose.

  • Of note, the dose is listed as units/hr and should be calculated as 0.1u/kg/hr. If your patient weighs 70kg, you would give 7 units per hour.

• If you want to bridge to subq insulin, go back to the same “ED DKA/HHA Ordering” but scroll down to “basal/long acting insulin”

• Select “insulin glargine (100 units/ml) basal." Double click the order to input a dose.

  • Remember the dose will be 50% of the total IV insulin given.

Hyperkalemia is treated with a rapid bolus of IV insulin intended to shift potassium into the cells. Be sure to give this insulin with dextrose to prevent hypoglycemia.

• Search for the “ED Hyperkalemia Order Set”

• Select “insulin lispro (100units/ml) injectable IV push”

  • This will default to a dose of 5 units. You can re-dose again if needed. 

Sources:

Our lovely ED Pharmacy team

https://www.uptodate.com/contents/general-principles-of-insulin-therapy-in-diabetes-mellitus?search=insulin&source=search_result&selectedTitle=2%7E150&usage_type=default&display_rank=1

https://rushem.org/2021/05/16/basic-management-of-diabetesnot-just-for-internists/

https://rebelem.com/benefit-initial-insulin-bolus-diabetic-ketoacidosis/

POTD: Dextrose Containing Fluids

During my very brief stint as your TR I have received two separate requests to discuss dextrose-containing fluids so for today’s POTD we’re going to review the use of these dextrose fluids based on their various formulations. 

Dextrose containing fluids are often used in the management of hypoglycemia. Hypoglycemia is defined as an abnormally low plasma glucose level, typically below 60 or 70 mg/dl in adults. Oral repletion is preferred in patients who are awake, alert, and able to swallow. However, for patients with severe hypoglycemia or altered mental status, you likely need to give intravenous dextrose containing fluids. These fluids are commonly referred to by the percent of glucose present in the solution, such as D50, D10, D5, etc.

D50 contains 25g of glucose in 50mL of water. This usually comes as a prefilled syringe and is commonly referred to as “an amp of D50.” Admittedly this is the dextrose containing fluid I find myself ordering the most for acute hypoglycemia. It is readily available (can be found in any of the ED omnicells) and provides a quick bolus of glucose with about five times the amount of glucose present in a normal adult’s blood. However, D50’s hypertonic nature increases the risk of vascular and tissue damage. If administered into a small vein D50 can be irritating and may cause thrombophlebitis. Additionally, it is also prone to extravasation from the vein leading to skin irritation and, in severe cases, local scarring or skin necrosis. Given these complications, some people advocate for the use of D10 instead.

D10 often comes as 10g of glucose in 100mL of fluid. This fluid has a lower osmolarity compared to D50, which reduces the risk of extravasation and thrombophlebitis. The lower concentration of D10 also allows for easier titration to ensure the patient becomes normoglycemic without overshooting and causing hyperglycemia. From my googles and discussions, the primary defense against using D10 in acute hypoglycemia seems to be a concern about the time required to give D10 as compared to D50. However, it’s important to note that one amp of D50 should be infused over 2-3 minutes to avoid extravasation. Studies show that a 200mL bolus of D10 (containing 20g of glucose) can be administered via pressure bag and will enter the patient’s bloodstream as quickly as slow pushing an amp of D50 (containing 25g of glucose). At Maimo, D10 can be found in the ED pharmacy, but after pharmacy leaves at night you would have to get it sent down from central pharmacy (unless you’re in peds, where there is usually a few bag of D10). 

Speaking of pediatrics… the treatment of hypoglycemia is slightly different in children. To minimize vascular complications associated with highly concentrated dextrose fluids, we opt for using weight based volumes of more dilute fluids, such as D10 or D25.

The general rule of thumb is neonates and infants (less than 1 year old) should get D10, while toddlers and children (1-8 years old) should get D25. Adolescents (greater than 8 years old) can be given D50. Regardless of the dextrose concentration, the volume administered should provide 0.5g dextrose per kg. To conveniently calculate the dose in milliliters, we use the “Rule of 50” – multiply the type of dextrose solution by a factor of 5, 2, or 1 (ml/kg) to give a total of 50.

• D10: 10 x 5 = 50, so give 5ml/kg

• D25: 25 x 2 = 50, so give 2ml/kg

• D50: 50 x 1 = 50, so give 1ml/kg

Overall these rules can be summarized as:

• Neonates and infants <1 YO, give D10 at 5 ml/kg

• Toddlers and children 1-8 YO, give D25 at 2ml/kg

• Adolecents > 8YO, give D50 at 1ml/kg

Of note, we do not have D25 fluids in the Maimo ER so usually I’ve seen people give D10 regardless of the patient’s age. Though you can always get D25 from PICU or central pharmacy in a pinch you can always make it out of an amp of D50. To make D25, discard 25mL from the D50 ampule and then add 25mL of NS or sterile water back into the ampule. Similarly, to make D10, discard 40mL from the D50 ampule and replace it with 40mL of NS or sterile water.

And last but not least, D5 is another fluid option with 5g of dextrose in 100ml of fluid. This is another commonly used dextrose-containing fluid that can be found in all the ED Omni cells. However, this fluid is too dilute to be recommended as a bolus treatment for acute hypoglycemia. Instead, where it shines is as a maintenance fluid to maintain normoglycemia and prevent rebound hypoglycemic events.

Sources:

https://www.emdocs.net/em3am-hypoglycemia/

https://www.aliem.com/d50-vs-d10-severe-hypoglycemia-emergency-department/

https://pemcincinnati.com/blog/521-50-dextrose-volume-hypoglycemia/