0071643192.pdf

EMS AND DISASTER MEDICINE^914

LATE NTPHASE

■ Symptom-free interval, prior to onset of bone marrow suppression

■ Generally lasts 2–4 weeks

■ Again, higher exposure =shorter latent period.

MANIFEST-ILLNESSPHASE

■ Consists of the following “syndromes” that occur with increasing radiation

dose:

■ Hematopoietic syndrome

■ Bone marrow suppression with resultant complications

■ Survival likely with appropriate care

■ Gastrointestinal syndrome

■ Reappearance of GI symptoms

■ Survival possible with aggressive care

■ Cardiovascular/CNS syndrome (“neurovascular”)

■ Altered mentation and hypotension typically occurring immediately

following exposure

■ Universally lethal with death in 24–72 hours

DIAGNOSIS

■ Exposure history

■ A Geiger-Mueller counter can detect all contaminating ionizing radiation

(depending on model).

■ The actual exposure dose is often not known, but can be estimated by clin-

ical or laboratory findings (“biologic dosimetry”):

■ The timing of onset of prodromal symptoms.

■ No vomiting by 4 hours →nonlethal dose.

■ Vomiting in <2 hours →serious/lethal dose.

■ Timing of onset of lymphocyte depletion

■ Rapid decline (over hours) =serious/lethal dose.

TABLE 20.11. Acute radiation syndrome

APPROXIMATE ONSET OF DURATION OF

DOSE PRODROME LATENTPHASE MANIFESTILLNESS

>2 gy (200 rad) Within 2 days 1–3 weeks Hematopoietic syndrome with

pancytopenia, infection, and

hemorrhage; survival possible

>6 gy (600 rad) Within hours <1 week GI syndrome with dehydration,

electrolyte abnormalities,

GI bleeding, and fulminant

enterocolitis; uniformly fatal

>30 gy (3000 rad) Within minutes None Cardiovascular/CNS syndrome

with refractory hypotension

and circulatory collapse; fatal

within 24–72 h

(Reproduced, with permission, from Tintinalli JE, Kelen GD, Stapczynski JS, Emergency Medicine:

A Comprehensive Study Guide, 6th ed. New York: McGraw-Hill, 2004:56.)

Estimating exposure dose

after whole body radiation:

Timing of onset of prodromal

symptoms (earlier =higher

dose) and/or

Timing of onset of lymphocyte

depletion (earlier/rapid =

higher dose)