Corneal Foreign Bodies

Corneal Foreign Bodies

·      Corneal foreign bodies account for approximately 35% of all eye injuries seen in the ED

·      Corneal foreign bodies are usually superficial and benign, but penetration into the globe can cause loss of vision

·      Foreign bodies are generally small pieces of metal, wood, or plastic

·      The presence of a corneal foreign body causes an inflammatory reaction, dilating blood vessels of the conjunctiva and causing edema of the lids, conjunctiva, and cornea

·      If present for >24 hours, WBCs may migrate into the cornea and anterior chamber as a sign of iritis

·      Occasionally, the foreign body may be visible with the naked eye

·      Evert the lid to identify and remove other foreign bodies

·      When a metallic foreign body is present for more than a few hours, a rust ring develops around the metal

·      The presence of a gross hyphema or a microhyphema evident in the anterior chamber on slit lamp examination suggests globe perforation

·      If the foreign body has penetrated the cornea, the tract of the projectile may be seen. The Seidel test may be positive with penetration of the globe

·      Contact lens use should be avoided until the defect is fully healed or feels normal for at least 1 week.

Foreign Body Removal

·      Anesthetize the cornea with a local anesthetic

·      Anesthetizing both eyes can be helpful, because that can eliminate reflex blinking during attempts at foreign body removal

·      Irrigate with normal saline first, as a very superficial foreign body may be irrigated off the cornea

·      Next, try to dislodge the foreign body with a moistened cotton applicator (Q-tip)

·      If the foreign body is tightly adherent to or embedded in the cornea, inspect the cornea using optic sectioning on the slit lamp to assess the depth of penetration

·      Full-thickness corneal foreign bodies should be removed by an ophthalmologist

·      For superficial foreign bodies, a 25-gauge needle (using needle bevel up) or a sterile foreign body spud (1 mm diameter) on an Alger brush (a low-speed, low-torque, battery-operated hand-held drill) can be used to remove the foreign body

·      Using either the 25-gauge needle or the Alger brush, place the tip into the slit lamp beam using the naked eye

·      Using the bevel-up edge of the tip of the 25-gauge needle, hook the edge of the foreign body and dislodge it. You may then lift it off the cornea using the previously moistened cotton applicator

·      Alternatively, using the spinning tip of the Alger brush, the foreign body may be dislodged and removed with the cotton applicator as above.

·      Administer tetanus toxoid as appropriate.

·      Provide ophthalmology follow-up the NEXT DAY if the foreign body is in the central visual axis or if there is a residual rust ring.

·      Otherwise, after complete removal of the foreign body, advise follow-up in 48 hours.

·      After successful foreign body removal, discharge the patient with a prescription for topical antibiotics, cycloplegics, and oral analgesics.

Antibiotics

·      Does Not Wear Contact Lens

o   Erythromycin ointment qid x 3-5d OR

o   Ciprofloxacin 0.3% ophthalmic solution 2 drops q6 hours OR

o   Ofloxacin 0.3% solution 2 drops q6 hours

·      Wears Contact Lens

o   Antibiotics should cover pseudomonas and favor 3rd or 4th generation fluoroquinolones

o   Moxifloxacin 0.5% solution 2 drops every 2 hours for 2 days THEN q6hrs for 5 days OR

o   Tobramycin 0.3% solution 2 drops q6hrs for 5 days OR

o   Gatifloxacin 0.5% solution 2 drops every 2 hours for 2 days THEN q6hrs for 5 days OR

o   Gentamicin 0.3% solution 2 drops six times for 5 days

Rust Ring Removal

·      Metallic foreign bodies can create rust rings that are toxic to the corneal tissue.

·      If a rust ring is present, the spud or an ophthalmic burr can remove superficial rust, but rust often reaccumulates by the next day, requiring additional burring.

·      It is therefore not necessary to remove a rust ring in the ED if the patient can be seen by an ophthalmologist the next day

·      Once the metallic foreign body is removed, the rust ring area softens overnight and can be more easily removed in the office the next day

·      The deeper the stromal involvement, the higher is the risk of corneal scarring, so if rust ring removal is done in the ED, only perform superficial burring

·      No ED drill burring should take place if the rust ring is in the visual axis (pupil) owing to the risk of causing visually significant scarring

References

Tintinalli’s Emergency Medicine a Comprehensive Study Guide 8th Edition

https://litfl.com/something-in-my-eye-doc/

https://accessemergencymedicine.mhmedical.com/content.aspx?bookid=683&sectionid=45343806

https://wikem.org/wiki/Ocular_foreign_body

Lethal Analgesic Dyad – Opioids + (Benzodiazepines or Gabapentin)

Opioids and benzodiazepines are increasingly used alone or in combination. However, the combined use of these agents increases the risk for potentially lethal respiratory depression.

Gabapentin is a drug often used together with opioids to treat chronic pain, and both have been shown to suppress breathing with worsening complications rates in combination.

General

·      In 2019, 16% of overdose deaths involving opioids also involved benzodiazepines

·      Every day, more than 136 Americans die after overdosing on opioids

·      From 1996 and 2013, benzodiazepine prescription increased by 67%, from 8.1 million to 13.5 million

·      Many people are prescribed both drugs simultaneously

·      In 2016, the Centers for Disease Control and Prevention (CDC) issued new guidelines for the prescribing of opioids. They recommend that clinicians avoid prescribing benzodiazepines concurrently with opioids whenever possible

·      Both prescription opioids and benzodiazepines now carry FDA "black box" warnings on the label highlighting the dangers of using these drugs together

Pathophysiology:

·      Opioids act on the opioid receptor, most prominently the µ-opioid receptor, is associated with the analgesic, respiratory depressant and rewarding effects of opioids

·      Opioids’ main effect is a reduction in respiratory rate which is caused by its direct inhibitory effects on mu receptors in the brainstem

·      Benzodiazepines are agonists of the GABAa receptor and predominantly bind the a1 and a2 subunits of this receptor, inhibiting neuronal signal transmission

·      Benzodiazepine respiratory depression is primarily characterized by a reduction in tidal volume

·      The affinity of the various types of benzodiazepines to the alpha units on the GABAa receptor determines their predominant clinical effect (i.e., sedation or anxiolysis).

·      Both benzodiazepines and opioids reduce upper airway patency and cause obstructive apneas and hypopneas

Interesting Article

This article focused on 29 manuscripts written regarding opioid and benzo interactions and separated manuscripts reviewed based on the clinical context: abuse and addiction, palliative healthcare, inpatient healthcare, and ambulatory healthcare

Abuse and Addiction

·      13 manuscripts identified.

·      The use of opioids with benzodiazepines or other centrally acting drugs has increased over the years

·      This drug combination increases the risk for mortality significantly. 

·      Interestingly, patients on methadone replacement therapy may be at higher risk for mortality and severe adverse respiratory events when concomitantly using benzodiazepines, than patients on buprenorphine replacement therapy

Palliative Healthcare

·      1 manuscript identified

·      This study found that survival in terminally ill patients was not reduced by concomitant use of an opioid with a benzodiazepine or antipsychotic

·      In fact, the chance of surviving longer in this setting was higher

·      May be safe in this context, however additional research is needed to corroborate these results

Inpatient Healthcare

·      3 manuscripts identified

·      They concluded that combined use of opioids and sedatives are likely to increase the risk for in hospital cardiopulmonary and respiratory adverse events and postoperative mortality

Ambulatory Healthcare

·      12 manuscripts identified

·      Looked at a variety of subpopulations including those who are receiving opioids and benzos for chronic non cancer related pain, cancer pain, psychiatric disorders, end stage COPD, and HIV

·      Data suggests that the combined use of opioids and benzodiazepines increases the risk for mortality among a variety of subpopulations

Opioids + Gabapentin

·      Gabapentin is a drug often used together with opioids to treat chronic pain, and both drugs have been shown to suppress breathing, which can be fatal

·      Concomitant opioid use can also increase the amount of gabapentin absorbed by the body, potentially leading to higher risks when these drugs are used together

·      When used together there was an association of 49% increased risk of dying from an opioid overdose

Tips:

·      Be mindful of the medications you are prescribing to your patients

·      Please look on DrFirst and or obtain a list of current medications that patient is taking.

·      Opioids + Benzos can lead to a potentially lethal respiratory depression

·      Be aware that Opioids and Gabapentin have a similar dangerous interaction causing respiratory suppression and death.

·      Make sure the patient has adequate follow up and consider alternative types of analgesia for patients with chronic pain.

References:

https://apm.amegroups.com/article/view/35734/29319

https://nida.nih.gov/drug-topics/opioids/benzodiazepines-opioids

https://www.bmj.com/content/356/bmj.j1224

https://www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNMattersArticles/downloads/SE19011.pdf

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5626029/

Galea Lacerations

Anatomy:

 The galea is a dense white layer that covers the periosteum of the skull. It serves as an insertion point for the frontalis and occipitalis muscles

Five layers of the scalp

·      SCALP

o   Skin

o   Dense Connective tissue

o   Aponeurosis (galea)

o   Loose connective tissue

o   Periosteum

Dense connective tissue layer is richly vascularized. The tight adhesion of these vessels to the connective tissue inhibits effective vasoconstriction, hence the large amount of bleeding in scalp lacerations.

The loose connective tissue layer = the DANGER ZONE when lacerated. This layer contains the emissary veins, which connect with the intracranial venous sinuses. Lacerations at this layer are high risk for spreading infection to the meninges!

Approach:

·      Examine the wound, clear of debris, and assess the depth of the wound.

o   Superficial wounds generally don’t gape

o   Deep wounds gape widely due to laceration of aponeurosis, and the tension from the frontalis muscle and occipitalis muscle pull the wound open in opposite directions

·      Hair removal unnecessary unless it interferes with actual closure or knot tying. No increased risk of infection if you do not remove the hair. Shaving head increases risk for infection!

·      Obtain hemostasis with pressure and lidocaine with epinephrine.

·      If the galea is lacerated more than 0.5 cm it should be repaired with 3-0 or 4-0 absorbable sutures. to prevent a serious cosmetic deformity from developing.

·      Skin can be repaired using staples; interrupted, mattress, or running sutures, such as 3-0 or 4-0 nylon sutures; or the hair apposition technique. Removal of sutures or staples in 14 days.

·      Antibiotics - With open skull fractures (blunt or penetrating), should give antibiotics: Ceftriaxone 2 grams q12hr + vancomycin for 24 hours.

Complications:

·      Asymmetric contraction of the frontalis muscle

·      Osteomyelitis, brain abscess - Failure to repair can also allow bacteria to get to the loose connective tissue layer more easily between the galea and periosteum, leading to increased risk of infection

·      Subgaleal hematoma

References:

https://sjrhem.ca/rcp-scalp-lacerations-you-can-leave-your-hat-on/

http://pemsource.org/2019/01/01/question-trauma-10/

https://aneskey.com/special-anatomic-sites/

https://www.aafp.org/afp/2017/0515/p628.html

https://www.vumc.org/trauma-and-scc/sites/default/files/public_files/Protocols/Antibiotics%20in%20CranioFacial%20Trauma%202021.pdf

Tintinallis Emergency Medicine a Comprehensive Study Guide 8th Edition