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Enoxaparin is the most commonly prescribed LMWH

in the ED. The most common dosing regimen is 1 mg/kg

subcutaneously every 12 hours. Dosing will need to be

adjusted in morbidly obese patients or those in renal

failure. Protamine (1 mg/1 mg enoxaparin) can be

administered to a maximum dose of 50 mg when r eversal

is indicated, but reversal is not as effective as with unfractionated hepar in. If major or life-threatening bleeds

occur, consider giving blood products such as PRBC and

FFP.

If warfarin therapy is being initiated in the ED, the

usual starting dose is 5 mg by mouth daily. Lower doses are

usually required in the elderly, in patients with liver disease, or those with poor nutrition. The therapeutic range

for the INR depends on the indication. Patients with

mechanical valves are considered therapeutic at INR levels

of 2.5-3.5, whereas other patients ( eg, with AF or VTE) are

therapeutic at INR levels of 2-3 .

Management of bleeding complications or supratherapeutic INR with warfarin is outlined in Figure 73- 1.

CHAPTER 73

No bleeding

Warfa ri n

anticoagu lation

Red uce or omit

next dose of

warfarin

Recheck INR

in 24 hr

Hold warfarin

Recheck INR

in 24 hr

Hold warfarin

Vitamin K 3-5

mg PO

Recheck INR

in 24 hr

Hold warfarin

Vitamin K 10

mg IV Hold warfarin

Vitamin K 10

mg IV

FFP 3-4 units

FFP 3-4 units

• Figure 73-1. Anticoagulant therapy and its compl ications diagnostic algorithm for supratherapeutic INR

from warfarin. FFP, fresh-frozen plasma; INR, international normal ized ratio; IV, intravenous; PO, by mouth.

For reversal, N administration of vitamin K is most rapid,

with onset within 1 -2 hours, compared with 6-10 hours

for oral dosing. Administer N vitamin K over 30 minutes

to minimize the small risk of anaphylaxis. Higher doses

of vitamin K (10 mg) may result in warfarin resistance

(up to 1 week) when it is time to restart anticoagulation

therapy. FFP is used as the flrst-line agent for reversal of

bleeding due to warfarin. The initial dose is 2-4 units.

Consider giving other products such as prothrombin

complex concentrate (PCC) and recombinant factor

VIla.

The oral direct thrombin inhibitor dabigatran is not

routinely started in the ED. However, more patients are

presenting to the ED on dabigatran with bleeding

complications. Currently there is no antidote for the

reversal of bleeding complications associated with its use.

Therefore, clinical management consists of stopping the

medication, and if a major or life-threatening bleed occurs,

consider giving FFP, PRBC, or some in vitro studies suggest

PCC or recombinant factor Vlla.

DISPOSITION

� Admission

A patient requiring anticoagulation therapy with heparin is

usually admitted to the hospital for coadministration with

warfarin. This is to prevent the hypercoagulable state that

occurs in the early phase of warfarin treatment. Patients with

a supratherapeutic INR and bleeding require admission.

Patients with a supratherapeutic INR who have a poor social

situation or are at risk of falling should also be admitted.

� Discharge

A patient with no other admission indications who requires

anticoagulation may be discharged with warfarin and a

7 -day course of LMWH injections. Close follow-up should

be arranged within 24-48 hours, and the patient must be

knowledgeable about self-inj ecting. Patients with

supratherapeutic INR without bleeding are frequently safe

to discharge if they are not at increased risk of falling.

ANTICOAGU LANT THERAPY AND ITS COMPLICATIONS

SUGGESTED READING

Agena W, Gallus AS, Wittkowsky A, et al. Oral Anticoagulant

Therapy: Antithrombotic Therapy and Prevention ofThrombosis,

9th ed: American Collage of Chest Physicians Evidence-Based

Clinical Practice Guidelines. Chest. 2012;141(Suppl):e44s--e88s.

Garcia DA, Baglin TP, Weitz JI, et al. Parenteral Anticoagulants:

Antithrombotic Therapy and Prevention of Thrombosis, 9th

ed: American Collage of Chest Physicians Evidence-Based

Clinical Practice Guidelines. Chest. 2012;141(Suppl):e24s-e43s.

Slattery DE, Pollack CV. Anticoagulants, antiplatelet agents, and

fibrinolytics. ln: Tintinalli JE, Stapczynski JS, Ma OJ, Cline

DM, Cydulka RK, Meckler GD. Tintinalli's Emergency

Medicine: A Comprehensive Study Guide. 7th ed. New York,

NY: McGraw-Hill, 20 1 1, pp. 1 500-1 507.

S lit Lam p Examination

Douglas S. Franzen, MD

Nathan J. Lewis, MD

Key Points

• Familiarity with the controls is critical to performing a

slit lamp examination.

• When positioning the patient for the exam, make sure

that their forehead is touching the forehead brace and

encourage them to keep it there.

INDICATIONS

The slit lamp is used to evaluate the anterior eye including

the lids, lashes, conjunctiva, cornea, visible sclera, anterior

chamber, iris, and lens for signs of trauma, hemorrhage,

inflammation, or foreign bodies.

CONTRAINDICATIONS

The patient must be cooperative and capable of sitting

upright for the duration of the examination.

EQUIPMENT

In addition to a slit lamp, the examiner will need 2 chairs

or stools, preferably of about equal height. Fluorescein

allows visualization of corneal injury. Other s upplies may

include anesthetic drops and a needle or ophthalmic burr

(for foreign body removal), cotton-tipped applicators (for

lid eversion), and saline (to flush the eyes or lids).

Ideally, one should be familiar with use of the slit lamp

before examining a patient. The slit lamp is a microscope

in which focus is achieved by moving the lenses instead of

the object being examined. The power of the microscope

typically ranges from 1 0-25x (or higher) and is adjusted by

a dial on the housing j ust in front of the eyepieces. The

plane of focus is changed by using the joystick to move the

• When using a slit lamp to remove a corneal foreign body,

first guide the removal device (eg, 25-gauge needle) to the

eye under direct vision, then switch to the magnified view.

• To prevent puncturing the cornea, keep the removal

device tangential to the globe at all times.

microscope toward or away from the patient. The joystick

also moves the microscope left or right. Twisting the

joystick raises or lowers the microscope. If the microscope

does not move when the joystick is moved, you may need

to loosen the locking screw on the microscope base.

The light source is mounted on a swing arm that allows

it to move independently from the microscope. Knowing

how to adjust the multiple controls of the light source is

critical to performing an exam. The power switch activates

the lamp. Many slit lamps also have a rheostat (dimmer),

usually near the power switch or on the base of the

microscope. A selector switch near the base of the bulb

housing allows the examiner to change from white to cobalt

blue light (other options, including green, are usually available). Just below this is a dial to adjust the height of the light

beam. Near the base of the microscope arm is another dial

to adjust the width of the slit. The location of these controls

may vary from lamp to lamp. Figure 74-1 demonstrates

their position on one model.

PROCEDURE

The patient should be seated and the height of the slit lamp

adjusted so the patient can place his or her chin comfortably

on the chinrest and forehead against the forehead brace.

The height of the chinrest should be adjusted so that the

patient's lateral canthus is aligned with the eye level mark

312

SLIT LAMP EXAMINATION

Forehead brace

Chinrest height -1--.....,

adjustment

Figure 74-1. Key components of the slit lamp.

on the chinrest support. The examiner should sit opposite

the patient in a chair or stool of about the same height.

Ask the patient to close his or her eyes. Turn on the lamp

with a white filter and adjust the brightness as needed. Move

the microscope to grossly focus the beam on the patient's

closed lid. Adjust the slit width to make the beam as narrow

as possible without losing brightness. Swing the light source

approximately 45 degrees to your right while leaving the

microscope directly facing the patient. Ask the patient to

open his or her eyes. When you look through the eyepieces,

the image should be very close to focused. Two reflections

will be visible: one that is curved and faint and, to the left of

that, one that is straight and much brighter. The curved

beam is reflecting off of the cornea. Adjust the microscope

so this beam is crisply focused (usually by moving slightly

toward the patient, about 1 mm). Protein deposits are often

visible on the corneal surface when properly focused

(Figure 74-2). Scan the left half of the patient's cornea by

using the joystick. Move in an arc so the plane of focus follows the curve of the patient's cornea--closer to the patient

as you approach the limbus and further from the patient as

you move toward the pupil. Look for any corneal defects or

foreign bodies. Check for ciliary flush (dilated pericorneal

blood vessels, a sign of iridocyclitis) at the edges of the cornea. It may be necessary to have the patient look up, down,

left, and/or right to fully view all parts of the cornea. After

scanning the left half of the cornea, bring the microscope

back to midline, swing the light source 45 degrees to your

left, and examine the right half of the patient's cornea. The

lids and conjunctiva can also be examined using this

method, usually with a wider beam.

After examining the patient with white light, fluorescein

should be instilled. Switch to the cobalt blue filter, widen

the light beam slightly, and repeat the exam. Look for areas

Bulb housing

Filter selector

Slit height

Eyepieces

.. ..

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