1 one treatment, two diseasesPYNEH Presenters: Dr Helen Wu, Dr HP Shum Chairman: Dr KW Chan one treatment, two diseases

2 Case 1 Ms Fok, 25 yrs old Good past healthAdmitted on 27/5/08, found lying unconscious inside a villa in Cheung Chau, burning charcoal was found at the scene; her boyfriend was found dead Transferred by helicopter to PYNEH

3 E1VTM1, pupils 3+ SaO2 100% on 100% O2 BP 117/88, sinus tachycardia 168/min Temp 38.1C Chest, CVS exam unremarkable No major trauma

4 TnT 0.43 ECG: sinus tachycardia with poor R wave progression over V1-2 COHb 13.9% Dx: CO poisoning Hyperbaric chamber contacted for urgent HBO therapy Consult ENT x bilateral myringotomies Post HBO COHb 1.2%

5 COHb 13.9%, 1.2%, 0.8%, 1.1%

6 2nd and 3rd session of HBO performed on D2 and D3 respectivelyExtubated on D3 E4V5M6 Transferred to general ward on D3 Seen by psychiatrist and discharged home on D16

7 Case 2 Ms Chan, 34 yrs old, 24th week gestationAdjustment disorder, hx of suicide in 2007 Found collapse at home, burning charcoal was found at scene E4V1M1 BP 93/23, P 70 ECG: SR, no acute ishcaemic change Fetal HR 169/min

8 COHb 18.9% Dx: CO poisoning Intubated with RSI Bilateral myringotomies performed by ENT Transferred to Stonecutters Island x HBO on the same day Post HBO COHb 1.2% E4VTM6 and extubated on D2 Sessions of HBO performed on D2 and D3 Transfer to general ward on D3 Discharged home on D6

9 Case 3 M/40, Ah Sing Mainland professional diverDived at 20m depth, no scuba, worked for 1hr and then saw ghost and quickly ascended to sea surface SOB, multiple joint pain, abdominal pain, transient LOC x 20-25min No drug/alcohol intake

10 GCS 15/15 BP 166/85, SR 105/min SaO2 100% on 100% O2, RR 20/min Chest: slightly AE over L side Abdomen: diffuse guarding RUL power 1/5, other limbs power 5/5

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13 Dx: decompression sicknessbilateral chest drain inserted Bilateral myringotomies performed 1st session of recompression Urgent contrast swallow: no definite leakage in thoracic region

14 CT abdomen: small pocket of air over posterior aspect of L lobe of liver

15 CT abdomen: gas between the spleen and the aorta with posterior relation to the pancreas

16 2nd, 3rd and 4th session recompression on D2, D3 and D4 respectivelyPersistent RUL monoparesis CT brain: hypodensity over L frontal- occipital lobe ?recent infarct MRI brain: acute infarct over L fronto- parietal region Dx: deompression illness with pneumothorax, pneumoperitoneum and cerebral air embolism

17 Use of Hyperbaric Oxygen

18 Physiological basic of HBOBased on gas laws Henry’s law Dalton’s law Boyle’s law Pascal’s principle

19 Henry’s law At constant temperature, the amount of gas that will dissolve in a liquid is proportional to the partial pressure of that gas over the liquid 1 ATA = x litres of gas in solution 10 ATA = 10x liters of gas in solution Drive more oxygen dissolve in plasma and increase oxygen delivery to tissue even when Hb oxygen carrying capacity is impaired

20 Dalton’s law The total pressure exerted by a mixture of gases is the sum of the partial pressures that would be exerted by each of the gases if it alone occupied the total volume Flooding the body with one gas tends to “wash out” the others

21 Boyle’s law At constant temperature, the absolute pressure and the volume of gas are inversely proportional In decompression sickness, nitrogen initially dissolved within the blood may come out of solution and causing gas embolism

22 Pascal’s principle A pressure applied to a liquid will be transmitted “equally” throughout the liquid

23 Physiological effect of HBOIncreased O2 delivery O2/ antioxidant balance disturbed by increased PO2 Oxygen toxicity CNS: seizure, vertigo, hallucination Pulmonary: burning on inspiration, SOB, coughing Pressure difference between body compartments Barotrauma affecting middle ear / sinus Decompression illness

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25 Carbon monoxide poisoning and use of hyperbaric oxygen

26 Carbon monoxide A colorless, odorless, non-irritating gas produced primarily by incomplete combustion of any carbonaceous fossil fuel Burning charcoal has become a popular way of attempting suicide in Hong Kong Incidence rate increased from 6% to 28% in the period between 1998 and 2001 Second most common method of suicide in Hong Kong Hong Kong Med J 2003; 9:419-26

27 Pathophysiology Hemoglobin bindingAffinity more than 200 times that of oxygen Decreasing oxygen delivery to the tissues and resulting in tissue hypoxia Am J Physiol 1944;141:17-31

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29 Acute effects More symptomatic in those with cardiac disease

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31 Delayed neurologic sequelae (DNS)Latency period of 2 to 40 days Ranged from 1-47% More frequent in those present with coma, in older patients and those with prolonged exposure

32 Some describe “ persistent neurological sequelae” vs “delayed neurological sequelae”, PNS may improve but not upto premorbid status, DNS refer to relapse of neurological symptom after period of improvement. Difficult to differentiate between two

33 CO poisoning in pregnancyCO crosses the placenta readily Fetal CO-Hgb levels reach higher peak and eliminate more slowly than maternal CO-Hgb Even in mildly symptomatic mothers, the effect on fetus may be severe Stillbirth Anatomic malformations Neurologic disability Fetal brain damage located at basal ganglia and globus pallidus Ann Emerg Med 1988;17(7):714-7 J toxicol ClinToxicol 1982;19(3): Neurology 1976;26(1):15-23

34 General CO poisoning managementMaintain an open airway and assist ventilation if necessary Give supplemental oxygen (100% O2 shorten elimination t1/2 from 6 hrs to 1 hrs) Continuously monitor the ECG, haemodynamic condition and provide support if needed Treat seizures Consider the possibility of cyanide poisoning , methemoglobinemia and irritant gas injury

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36 History HBO for CO poisoning was first discussed by Haldane JS in the 1890s Haldane JS was known for experimentation on himself to find the amount of carbon dioxide in the blood was a stimulus for the respiratory centre of the brain. He reported on investigations of the effects of carbon monoxide from mine fires and explosions (1896). He produced the first staged decompression tables and apparatus (1907). He also invented a gas mask used in WW I.

37 Potential benefit of HBOHastens elimination of COHb (t½ decrease from 4-6 hr to <30min) Increase tissue oxygen delivery Promote CO dissoication from cytochrome-C oxidase Reduce brain lipid peroxidation Inhibit neutrophil activation and adhesion Science 1950; 111: 652-4 Toxicol Appl Pharmacol 1990; 105: 340-4 J Clin Invest 1992; 89: Toxicol Appl Pharmacol 1993; 123:

38 Prospective unblinded RCT 4 groups of patients, started within 12 hr Trial of normobaric and hyperbaric oxygen for acute carbon monoxide intoxication Prospective unblinded RCT 4 groups of patients, started within 12 hr No LOC: A0 (170) NBO x 6 hr vs A1 (173) HBO 2 ATA 2h + 4h NBO -> FU 1mo -> 34 vs 32% with DNS LOC: B1 (145) HBO 1 session vs B2 (141) 2 session HBO -> FU 1 mo -> 46 vs 48% with DNS Conclusion: HBO is useful in those with LOC but multiple sessions of HBO may not give extra benefit Rahael et al: Lancet Aug 19;2(8660):414-9

39 24 non comatous patients, RCT Non-comatose patients with acute carbon monoxide poisoning: hyperbaric or normobaric oxygenation? 24 non comatous patients, RCT 100% NBO vs 100% HBO (2.8 ATA) for 2h, followed by NBO x 10h COHb normalized both group NBO: more EEG abnormalities and reduced cerebral blood flow reactivity to acetazolamide Conclusion: HBO reduces the time of initial recovery and the number of delayed functional abnormalities in non-comatose patients with acute CO poisoning. Ducasse JL et al: Undersea Hyperb Med Mar;22(1):9-15.

40 Prospective RCT, unblinded Delayed neuropsychologic sequelae after carbon monoxide poisoning: prevention by treatment with hyperbaric oxygen. Prospective RCT, unblinded 65 non-comatose patients, within 6 hrs of removal from exposure All patients given 100% O2 till HBO started HBO: started within 6 hr, 2.8 ATA x 30min than 2 ATA x 90 min NBO: till symptom resolved (mean 4.2h) 4 wk FU DNS: 23% vs 0% in favor of HBO Conclusion: HBO treatment decreased the incidence of DNS after CO poisoning. Thom et al: Ann Emerg Med Apr;25(4):

41 Prospective unblinded RCT 575 non-comatose patient Randomized prospective study comparing the effects of HBO vs 12 hours NBO in non-comatose CO-poisoned patients Prospective unblinded RCT 575 non-comatose patient HBO 2.5 ATA 90min vs 12 hr NBO 1 month FU DNS 23% vs 26%, no significant difference between groups Conclusion: no significant benefit of HBO over NBO on CO poisoning Mathieu et al: Undersea Hyperb Med 1996, 23: suppl 27

42 Prospective, double blinded, RCT Hyperbaric or normobaric oxygen for acute carbon monoxide poisoning: a randomised controlled clinical trial Prospective, double blinded, RCT 230 patients, average COHb 21%, 50% with hx of LOC, within 7 hr Daily 100min 100% O2 tx within hyperbaric chamber, 60min 2.8 ATA HBO or 1 ATA NBO, three days 1 month FU was 46% DNS 65% vs 58% in favor of NBO Conclusion: HBO therapy did not benefit, and may have worsened, the outcome Scheinkestel et al: Med J Aust Mar 1;170(5):203-10

43 Hyperbaric oxygen for acute carbon monoxide poisoningProspective double RCT 152 patients, started within 24 hr, 65% with LOC HBO: 1 session 3 ATA 1 hr and 2 ATA 1 hr, followed by 2 sessions 2 ATA 2 hr at 6-12hr intervals NBO: sham tx at 1 ATA FU 12 mos DNS 25 vs 46% in favor of HBO Conclusion: Cognitive sequelae were less frequent in the HBO Weaver et al: N Engl J Med Oct 3;347(14):

44 Managing carbon monoxide poisoning with hyperbaric oxygenProspective unblinded, RCT 153 patients with hx of LOC HBO: 2 ATA 1 hr followed by NBO 4 hr NBO: 6 hr NBO tx FU 1 mo DNS HBO 42% vs NBO 39%, no difference Conclusion: HBO did not benefit the outcome Raphael et al: J Toxico Clin Toxico 2004; 42: 455-6

45 Favour HBO Favour NBO Cochrane Database Syst Rev. 2005 Jan 25;(1)Excluded Ducasse study because of inadequate allocation concealment and use of surrogate outcome measures Favour HBO Favour NBO Cochrane Database Syst Rev Jan 25;(1)

46 Existing randomized trials do not establish whether the administration of HBO to patients with carbon monoxide poisoning reduces the incidence of adverse neurologic outcomes. Additional research is needed to better define the role , if any, of HBO in the treatment of patients with carbon monoxide poisoning

47 US Royal Navy table 60 2.8 bar

48 Decompression illnessnitrogen bubbles forming in the bloodstream and tissues of the body move from deep water towards the surface in a short period of time. Type I Skin symptoms, lymph node swelling, joint/muscle pain Henry’s Law

49 Type II decompression illnessArterial gas embolism CNS – dizziness, paralysis, numbness, blurred vision, convulsion CVS – cardiopulmonary arrest pneumothorax Pneuomperitoneum Inner ear – tinnitus, hearing loss, vertigo, dizziness, nausea and vomiting

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51 Protocol for ICU patients undergoing HBO treatmentHazards exist if HBO therapy is not done with proper preparation and monitoring Balance between benefit obtained from HBO therapy and risk associated should be considered by ICU doctors

52 Insert chest drain before HBOMedical conditions requiring special consideration before HBO Neurological Seizure disorder Haematological Congenital spherocytosis Systemic Viral infection Hyperthermia Others Pregnancy Respiratory COPD / Asthma URTI Hx of thoracic surgery Hx or presence of pneumothorax CXR with asymptomatic pulmonary lesions Otolaryngologic Chronic sinusitis Hx of ear surgery Ophthalmologic Hx of optic neuritis Insert chest drain before HBO ENT assessment to ensure normal eustachian tube function and may need prophylactic myringotomy

53 Try to simplify patient’s treatment and monitoringExplain the risk and benefit to patients and relatives, get the consent Experienced ICU doctor should accompany the patient during the whole treatment period although he /she may not need to enter the pressure chamber Doctors on call of the hyperbaric chamber should be contacted directly

54 ETT / tracheostomy tube Mechanical ventilator systemUse water to inflate the cuff Mechanical ventilator system Oxylog 1000 is to be used within the chamber When the chamber pressure is changed, tidal volume delivered to patient will change accordingly and required adjustment Wright’s spirometer should be connected to the ventilator circuit for TV monitoring Anesthetic PEEP valve can be used if needed

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57 Chest tube drainage systemsMust have thoracostomy apparatus ready available within the chamber Chest drain box Maintain suction, monitor air-fluid level during ascent and descent Substitute with one-way valve (eg Heimlich valve) Oxygen breathing device Use of O2 within the chamber must be controlled carefully Only aqueous solutions should be used because of fire hazards

58 Central line placementIV infusion equipment Avoid glass bottles Iv infusion pump may carry potential fire hazard Ensure absolutely no air entrapment Avoid puncturing rubber injection sites and use 3 way stopcocks Nasogastric tubes Leave unclamped or on intermittent suction Central line placement Avoid subclavian puncture For PAC, ensure balloon at catheter tip is deflated and balloon port must be left open, avoid obtaining wedge pressure during the dive

59 Monitoring equipment SpaceLab monitor is available within chamberFor intra-arterial pressure monitoring Further inflate pressure bag during compression and deflate during decompression Avoid air entrapment within tubing Zero pressure transducer with reference to chamber pressure Function of pulse oximeters / capnography may be unreliable Do not put monitor with a hot wire stylus inside the chamber Make sure all device attached to patient’s body are HBO compatible

60 Injections Defibrillation Suction device Foley catheterAvoid IM/ SC injection because of impaired absorption due to vasocontriction secondary to HBO Be careful with multiple use vial Defibrillation Should only be done when the patient was surfaced because of fire hazard Suction device Available inside chamber Foley catheter Ensure balloon inflated with water

61 Staff accompanying patient should not carry combustible materialsNIBP Do not use mercury filled type Staff accompanying patient should not carry combustible materials Cigarettes, matches, lighters Oil based cosmetic, face cream, body oil, hair spray Nylon clothing Ink filled pen Electronic devices Pagers, mobile phone, watches (except diving watch)

62 Potential complications associated with HBOBarotrauma Most commonly involve the ear on descent, other sites including sinuses, lungs, teeth Oxygen toxicity Acute toxicity usually presented with seizure Other symptoms: palpitation, bradycardia, sweating, nausea, vertigo, hallucination Claustrophobia Reversible worsening of visual acuity Transient GI pain Fire / explosion hazards

63 Occupational safety and health for staffNormal eustachian tube function No hx of pneumothorax, COPD, chest surgery Not pregnant No recent diving

64 Occupational safety and health for staffNo flying after dive for at least 24 hr Stop at least 48 hrs before another dive Recognize symptoms of complications Barotrauma esp. ears Decompression illness eg joint pain / numbness/ weakness Inform OMD if DCI occur

65 Stonecutters Island (Ngong Shuen Chau)

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69 Control panel with the fireman

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71 Main entrance

72 Entry lock

73 Drinking water Sanitary facility Communication facility

74 Wright’s spirometer

75 Oxygen hose

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78 CO poisoning, PYNEH, 7 cases 3M, 4F All survived

79 AN uneventful 1 F 34 18.9  X 2 30 31 3 46 45 4 5 6 7 Patient GenderAge COHb% HBO energy pain emotion sleep social physical 1 F 34 18.9  X 2 30 31 3 46 45 4 5 6 7

80 Thank you! The end