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HYDROGEN SULFIDE: Does Hyperbaric Oxygen work?

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HYDROGEN SULFIDE: Does Hyperbaric Oxygen work? Case of the week December 12, 2003 Rob Hall MD H2S Knock-down case of the week! How is H2S toxic? Inhibits cytochrome ... – PowerPoint PPT presentation

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Title: HYDROGEN SULFIDE: Does Hyperbaric Oxygen work?


1
HYDROGEN SULFIDEDoes Hyperbaric Oxygen work?
  • Case of the week
  • December 12, 2003
  • Rob Hall MD

2
  • H2S
  • Knock-down case of the week!

3
How is H2S toxic?
  • Inhibits cytochrome oxidase
  • Thus inhibits oxidative phosphorylation
  • Anaerobic metabolism cant keep up!
  • -------------gt CELLULAR HYPOXIA
  • EARLY DEATH
  • Respiratory paralysis due to toxic effect at the
    respiratory centers

4
Permanent Neurologic Sequelae
  • Prolonged coma
  • Recurrent seizures
  • Chronic vegatative states
  • Tremors
  • Cognitive impairment

5
Why might HBOT be effective?
  • Increased oxygen delivery to tissues
  • Increased oxyhemoglobin which increases the
    auto-oxidation of sulfide

6
What are the TEXTBOOK recommendations for HBOT?
  • Haddad. 1998.
  • May be beneficial in patients in whom CNS
    symptoms do not resolve spontaneously or with
    prompt nitrite therapy
  • Ford.
  • Should be used in neurologically compromised or
    acidemic patients refractory to conventional
    therapy
  • Goldfrank 2003
  • All patients should receive HBOT if readily
    available transport solely for HBOT is
    unnecessary

7
H2S and HBOT
  • So what is the evidence??

8
1) Vicas. Vet Hum Toxicol 1989
  • 30 yo male
  • H2S contaminated petroleum
  • Unconcscious on arrival in ED
  • 3 HBO treatments 13 hr post exposure
  • 2 further HBO treatment
  • Increased LOC, memory, verbal interaction,
    problem solving
  • Persistent retrograde amnesia

9
2) Al-Mahesneh. Vet Hum Toxicol 1989
  • Acute exposure to known high H2S
  • Comatose, unresponsive, F/D pupil on arrival in
    the ED
  • Flown to hyperbaric chamber (?delay)
  • HBOT for 3 hours
  • NO improvement
  • Patient died at 56hrs after exposure

10
3) Snyder. Am J Emerg Med 1995
  • Construction pit on of New Jersey coast
  • Two men knocked down, several other rescuers
    knocked down, 1 Dead on scene
  • Worker 1
  • GCS 3 on arrival, sent for HBO
  • 12 hour delay until HBOT started

11
3) Snyder. Am J Emerg Med 1995
  • Day1
  • One session of 2ATA for 45 min
  • GCS 3 -gt 5
  • Day 2
  • Two sessions of 1.5 ATA for 90 min each
  • Day3 7
  • Two sessions of 1.0 ATA for 90 min each
  • Day 3 GCS 7, Day 5 GCS 11, Day 7 GCS 15
  • Day 8-16
  • One session of 1.0 ATA for 90 min

12
3) Snyder. Am J Emerg Med 1995
  • Persistent Neurological Sequelae
  • Slow speech, flat affect, inability to
    concentrate, impaired visual memory, easily
    distractible, confabulation
  • Neurologic Sequelae unchanged at 12 and 18 months

13
4) Schneider. Occ Med 1998
  • 27yo male
  • Building a sewer system in New Jersey
  • Rescuer died at the scene
  • GCS 3 on arrival at ED
  • Transfer for HBOT 10hrs after exposure
  • 2 ATA for 45 min bid X several days
  • Regained consciousness on day 5
  • GCS 11 on day 7 then improved to 15
  • Similar neurological sequelae to last case noted
    at one month and 4yrs post incident

14
Neuroimaging
  • CT head was normal in this case on day of
    exposure
  • MRI was normal at 17 months despite persistent
    neurological sequelae
  • PET scan at 3 years showed marked decrease in
    perfusion to thalamus, basal ganglia and abnormal
    metabolic patterns in the temporal and parietal
    lobes

15
NOTE
  • Normal CT or MRI of brain does not preclude
    permanent neurologic sequelae!

16
5) Smilkstein. J Emerg Med 1985
  • 34 yo male
  • Oil pump waste collection tank
  • GCS of 7 on arrival to ED
  • HBOT started 10hrs after exposure
  • Total of 12 HBOT treatments over 6 days
  • 1 2.5 ATA for 45 min
  • 2 2.0 ATA for 75 min
  • 3-12 2 ATA for 90-120 min
  • Outcome stepwise improvement, awake/alert by
    48hrs, slight difficulty with complex tasks
    persisted

17
6) Harefuah. 1994
  • Another Case report of H2S treated with HBOT
  • Hebrew!

18
The RATS have the last word! Bitterman. Tox Appl
Pharm 1986
  • Rat model several groups with 20 rats each
  • LD 75 dose of intraperitoneal sodium sulfide
  • Various treatments after sulfide injection
  • Group 1 no treatment
  • Group 2 sodium nitrite room air
  • Group 3 100 oxygen
  • Group 4 HBOT at 2 ATA
  • Group 5 sodium nitrite 3 ATA HBOT
  • Various treatments before sulfide injection
  • Group 7 HBOT 3 ATA
  • Group 8 sodium nitrite and HBOT 3ATA

19
The RATS have the last word! Bitterman. Tox Appl
Pharm 1986
pretreatement
rescue treatments
20
The RATS have the last word! Bitterman. Tox Appl
Pharm 1986
  • Conclusions from the rats
  • Methemoglobinemia alone not beneficial
  • Oxygen beneficial
  • HBOT methemoglobinemia beneficial

21
SUMMARY H2S and HBOT
  • 6 Case reports 5 ve, 1 -ve
  • Case reports have significant delay from exposure
    to HBOT does this matter?
  • 1 Animal model
  • NO case series
  • NO controlled trials

22
Summary
  • HBOT may have a role in the management of H2S
    toxicity but its efficacy is LARGELY UNKNOWN
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