Slides with topics that are covered and were tested in the recent Absite exams. Nir Hus MD., PhD. http://www.nirhus.com

1. Absite topics 4-6
Nir Hus
Nir Hus

2. Sulfamylon (Mafenide Sodium)
 Painful application – hyperosmolar.
 Can lead to metabolic ACIDOSIS
(hyperchlorimic).
 Carbonic anhydrase inhibition.
 ↓ renal conversion of H2CO3  H2O +CO2
 Can cause hypersensitivity reactions
 Has good eschar penetration
 Broad spectrum includes GNR & Pseudomonas.
Nir Hus

3. Anti-thrombin III deficiency
 2-3% spontaneous Venous thromboses
 Heparin will not work (nothing to activate)
 Can develop after previous heparin exposure
(consumption of AT-III).
 Tx –
 Give AT-III
 FFP (highest [AT-III])
 Followed by:
 Heparin
 Hirudin (Hirulog) – leeches, direct thrombin inhibitor., f/u w/ PTT.
 Ancrod – Malayan pit viper venom, stimulate tPA release.
 Coumadin at last – skin necrosis has synergistic increased risk.
Nir Hus

4. Brain Death
 Dx:
 EEG – electrical silence.
 MRA – needs to show lack of brain flow.
 Apnea test – disconnect from vent  CO2 >60mmHg results in
maximal stimulation of brain stem respiratory centers. Positive
test = no drive to breath. If arterial BP < 60 or Pt. desats 
terminate test.
 Deep tendon reflexes are NOT diagnostics, they can persist w/
brain death.
 Ocular Movements. Both oculocephalic (“doll’s eye”) and
vestibulo-ocular (caloric test) reflexes are absent in brain death.
 Pharyngeal and Tracheal Reflexes. Gag and cough reflexes are
absent in patients with brain death.
 The gag reflex can be evaluated by stimulating the posterior part of
the pharynx with a tongue blade, but the results can be difficult to
evaluate in orally intubated patients.
 The cough reflex can be tested by using bronchial suctioning.
Nir Hus

5. Brain Death
 Conditions that preclude Dx:
 Uremia
 Temp <30oC
 BP < 70/40
 Desaturation w/ apnea test
 Drugs such as phenobarbital.
 Metabolic derangments
Nir Hus

6. Nir Hus

7. Brain Death
 Transcranial Doppler Sonography
In transcranial Doppler sonography, intracranial arteries are insonated
bilaterally (ie, middle cerebral artery through the temporal bone above the
zygomatic arch)
 10% of Pt. may not have temporal insonation windows. Therefore, initial
absence of Doppler signals cannot be interpreted as consistent with brain
death.
 Findings consistent with brain death indicate high vascular resistance
associated with greatly increased intracranial pressure and include
 Absent diastolic or reverberating flow.
 Systolic-only flow or retrograde diastolic flow.
 Small systolic peaks in early systole. Blood flow velocities may be
influenced by marked changes in Pco2, hematocrit, and cardiac output.
 Somatosensory and Brain Stem Auditory Evoked Potentials
Bilateral stimulation of median nerves. Brain death - no responses to tests
for somatosensory and brain stem auditory evoked potentials.
 less sensitive than previously mentioned confirmatory tests.
Nir Hus