Questions of the Week for 12/19/2023

Authors: Christian Gerhart, Amjad Musleh

Q: The whole point of increasing PEEP is to recruit lung areas that are collapsed and not participating in gas exchange. How do you know if the increase in PEEP that you performed actually recruited more alveoli? 

• Answer

  The point of PEEP is to recruit alveoli. Two things can happen when you increase PEEP (see graphic below).

  The left side shows PEEP that does not recruit alveoli. (BAD – barotrauma/overdistention & hemodynamic collapse)

  • Plateau pressure will go up on vent in approximately the same amount that PEEP went up.

  • For example, if you started off at a PEEP 5 w/ plateau 30, then PEEP 10 will give you a plateau of 35

  The right side shows PEEP that recruits alveoli. (Good Scenario)

  • What this will look like on the vent: Plateau pressure should either stay the same or go down

  • For example, if you started off at PEEP 5 w/ plateau 30, then PEEP 10 will give you Plateau 30 or less.

Q: Can you estimate a PaO2 from an SpO2?

• Answer

  Once you have optimized your patient in terms of PEEP and tidal volume, the next steps to help improve oxygenation include sedation for vent synchrony, followed by a trial of paralytics, followed by inhaled epoprostenol or proning. The branch tree on deciding when to escalate to the next therapy is if the P/F ratio is less than 150. To do this, you need an ABG for a PaO2. Alternatively, one can use an SpO2 to estimate the PaO2. An SpO2 of 90% is equivalent to a PaO2 of 60mmHg. This means that a patient who is on room air (21% FiO2) and has an SpO2 of 90% has a P/F ratio of 60mmHg/0.21 ≈ 286. Someone that has a normal chest Xray does not qualify as having ARDS, even if their P/F ratio is less than 300.

Q: You have a patient who presents with a laceration over the flexor surface of the left pointer finger middle phalanx. What key exam maneuvers must be performed for this patient?

• Answer

  It is crucial to examine and document a thorough motor, sensory and vascular examination. Flexor surface injuries of the hand can be a landmine and it can be easy to miss an injury if the exam is inadequate. In this case, evaluation of the finger cascade, isolation of the flexor digitorum superficialis and flexor digitorum profundus with strength testing are vital. It is also important to note if the patient has significant pain with range of motion. Be sure to perform your complete examination before providing local anesthesia or a digital block. You will need to perform a thorough visual examination to check for tendinous injury and assess if there is any penetration into a joint depending on the location of the laceration.

  More information here:

  https://emergencymedicinecases.com/hand-injuries-assessment-management/

Q: Your patient above has normal strength and sensation and you do not note any clear tendon injury on exam. However, he has some pain with flexion of the digit. What diagnosis should be suspected?

• Answer

  A partial flexor digitorum superficialis injury should be suspected. These injuries are important to be suspicious of because they can turn into a full tendon rupture, which can have devastating consequences. If you are not sure if there is a partial injury or not, it is generally safest to immobilize the patient to prevent extension of the digit, which can worsen a partial injury, and refer the patient to a hand surgeon. 1 A guide to immobilization technique is provided below from the Journal of Emergency Medicine.2 For a flexor tendon injury, it is generally recommended to immobilized the hand in the “position of safety” with the wrist at 30-45 degrees of extension, the MCP flexed at about 70 degrees and the DIP/PIP joints at 0 degrees. Some authors recommend using a dorsal blocking splint to avoid excessive extension.

 Q: You are taking care of a young male with sickle cell SS disease who presents with priapism for the last 5 hours. Describe you approach to treatment.

• Answer

  Priapism in a patient with sickle cell disease is nearly always low-flow/ischemic, which needs to be more aggressively treated than non-ischemic priapism. Initial treatment should start with supportive care including pain control and IV fluids. A penile block can be performed prior to any intervention using a 27-gauge needle and 1% lidocaine without epinephrine with injection at the 10 o’clock and 2 o’clock positions near the base of the penis. Depending on the patient’s pain tolerance and age, they may require sedation for this procedure. Usually a butterfly needle (19 or 21 gauge) is used to enter the corpora cavernosa at the 10 o’clock and 2 o’clock positions and 30-60 mL of blood can be taken off, followed by irrigation with 10 mL aliquots of normal saline. If the patient’s symptoms persist, then phenylephrine can be used in doses of 100 mcg every 3-5 minutes. Most guidelines say that treatment failure is when this is attempted for an hour without success. Remember that the patient must be on the monitor when giving phenylephrine. If these measures fail urology should be contacted as the patient may require a shunting procedure. If the patient already has severe hypertension or is on a monoamine oxidase inhibitor, it may not be safe to use phenylephrine at all.

References:

1)    Roberts, James R. MD. ED Treatment of Flexor Tendon Injuries. Emergency Medicine News 33(12):p 8,9, December 2011. | DOI: 10.1097/01.EEM.0000410106.40227.cc.

2)    McEvenue G, FitzPatrick F, von Schroeder HP. An Educational Intervention to Improve Splinting of Common Hand Injuries. J Emerg Med. 2016;50(2):228-234. doi:10.1016/j.jemermed.2015.08.011.

3)    Deveci S. Priapism. UpToDate. https://www-uptodate-com.beckerproxy.wustl.edu/contents/priapism?search=priapism&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1. Published January 28, 2022. Accessed January 8, 2024.

4)    Levey HR, Segal RL, Bivalacqua TJ. Management of priapism: an update for clinicians. Ther Adv Urol. 2014;6(6):230-244. doi:10.1177/1756287214542096

5)    Burnett AL, Sharlip ID. Standard operating procedures for priapism. J Sex Med. 2013;10(1):180-194. doi:10.1111/j.1743-6109.2012.02707.x.

6)    Bivalacqua TJ, Allen BK, Brock G et al: Acute Ischemic Priapism: an AUA/SMSNA Guideline. J Urol 2021; 206: 1114.