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Issue 019--Oct 2021

Hong Kong Society
for Emergency Medicine & Surgery
Message from the President...
Time flies. It has been 2 years since I took up the post of the President of HKSEMS in October 2019. This is my last “Message from the President” on the newsletter of HKSEMS. In the forthcoming Annual General Meeting in October 2021, I will step down from the more
From Editors...

With the new term of council members of the society, there will be addition of new editors. We hope this can inject more energy to the production of the newsletter so as to bring more appealing contents to our readers as well as to tighten the distance between us and more 
Council News...                 
Various activities were held in the 3rd quarter of this year, including EEEM workshop, Point-of-care ultrasound course and Multi-specialty Medical Mega more
From Members
Members Area
Emergency Medicine is a relatively young specialty compared to other specialties. Dr Kam Chak Wah will review the development of EM, listing some important historical points throughout the more 
Private EM Writes

Dr Lam Ka Keung will write about an uncommon seen complication from minor head more

Nurse Corner
Seventeen years ago Hong Kong was hit hard by SARS. Last year the SARS-COV-2 attacked this city again. Ms Canmy Chan, APN of Tin Shui Wai Hospital A&E will write about her experience with these two more 
Advance in EM
Established in September 2018, the Hyperbaric Oxygen Therapy (“HBOT”) Centre is the first and the only HBOT Centre in Hong Kong, offering hyperbaric oxygen treatment services to local emergency patients. The HBO Subcommittee Vice-chairman of HKCEM, Dr  Chau Cheuk Wai Jeffrey will introduce to us the establishment of the center and its more
Message from the President      Dr Ben Kuang-An WAN
Time flies. It has been 2 years since I took up the post of the President of HKSEMS in October 2019. This is my last “Message from the President” on the newsletter of HKSEMS. In the forthcoming Annual General Meeting in October 2021, I will step down from the presidency. I would like to take this opportunity to review how we stayed united for the HKSEMS and the entire Emergency Medicine community in the past 2 years.
Since early 2020, the world has been ravaged by the COVID-19 pandemic. Millions of people died of this dreadful disease. Despite the rapid development of vaccines, the pandemic hasn’t been brought under control yet and in the foreseeable future we still need to wear masks and practise social distancing. The pandemic situation, travel restriction and prohibition of group gathering have unfortunately brought unprecedented challenges to our community work, educational activities, social activities for members and academic exchange with local and overseas organisations.
Despite the difficulties, HKSEMS has not stopped developing. Internally, new committees and subcommittees were established. The Health Education Committee was set up in accordance with our missions to promote EM knowledge to the community, though its functions and activities have been severely hampered by the pandemic. Thanks to the colleagues in the new IT subcommittees for their endeavors in the website revamp. I would also like to pay tribute to the editorial board of the HKSEMS newsletter, for their efforts to bring diversified contents in the newsletter.
Externally, HKSEMS has been working with other local EM professional bodies. Asian Conference on Emergency Medicine (ACEM) 2021, co-organized with Hong Kong College of Emergency Medicine (HKCEM) and supported by Hong Kong College of Emergency Nursing (HKCEN) and Hong Kong Emergency Nurses Association (HKENA), will be held in December 2021. It’s a biennial flagship EM conference in Asia. We invited different stakeholders and kick-started the preparation in 2018. It was initially planned as a face-to-face academic conference but later the Organizing Committee decided to go for a virtual conference to mitigate disruptions by the COVID-19 pandemic. Though it will be held on a virtual platform, the Organizing Committee and the Scientific Committee has paid tremendous efforts to ensure the educational values and interactive opportunities.
We continued to look after the needs of local EM community. For example, in July 2020 HKSEMS collaborated with HKCEM to publish a positional statement to address the unique role of A&E services in the COVID-19 pandemic and to discourage improper use of A&E resources to screen for COVID-19 in asymptomatic people. The pandemic created a new norm in medical education, characterized by online or blended learning. Educational activities of HKSEMS have been gradually resumed thereafter. HKSEMS councillors and members have also conveyed health messages to the public through media interviews, newspapers, and publications during the pandemic.
I would like to take this precious opportunity to express my gratitude to all the councilors and members who strode with us in difficult times. I wish my successor all the best, and I am confident that the new council will lead HKSEMS to reach a new high.
From Editors Editors in chief Dr Sam Siu-ming Yang

Dr Ho-yin Chan, Dr Wendy Cheng,
Dr Ka Keung Lam, Dr Kwun-bun Wong
Mr Chun Pong Leung
This issue of newsletter comprised of some interesting topics.
Dr Jeffrey Chau will share with us the establishment of the first hyperbaric oxygen therapy center. He will also introduce the various treatment indication of hyperbaric oxygen and share his experience of the work in the center.
In the private EM column, Dr Lam Ka Keung will discuss an uncommon yet interesting topic: traumatic intracranial hypotension. Such complication from head injury is not commonly seen but can be distressing to patient.  
In the members area, Dr Kam Chak Wah will write up on the development of EM, listing some important historical points throughout the years.
Times flies, it has been more than four years since we started this newsletter. Thanks to the help of all editors and EM physician as well as nurses who made contributions to the newsletter, the newsletter has been enriched with interesting contents throughout the years. We underwent a modification in our outlook last year to include column from the members, private EM physicians, EM nurses as well as a column on cutting edge development of EM news/knowledge. This led to a surge on the open rate of the newsletter. The feedback was good and this provided the necessary encouragement for us to move forward.
With the new term of council members of the society, there will be addition of new editors. We hope this can inject more energy to the production of the newsletter so as to bring more appealing contents to our readers as well as to tighten the distance between us and members.

Council News

Dear Members of HKSEMS,
Welcome to the 3rd issue of 2021. Let us refresh the activities organized the Council in the last 3 months!!
Farewell to Dr. Ng Man Ho- our respectable leader of the HKSEMS
Dr. Ng Man Ho has served the HKSEMS for 24 years. He was elected as the President in the year of 2003-2009. We would like to thank Dr Ng for his contribution and leadership over the past years!!
The 2019-2021 Council with Dr. Ng Man Ho.
Dr. Ben Wan, the president of the HKSEMS, presented a souvenir to Dr. Ng Man Ho.

Induction program on Emergency Medicine co-organized by HKSEMS and HAHO IEC
This induction program, a conjoint function of the HKSEMS and the Hospital Authority Head Office IEC (Infection, Emergency and Contingency), was held on 9 July 2021 using ZOOM platform. This is a half-day program, aiming to offer newcomers, including Emergency Medicine basic trainees and trainees/interns of other specialties rotated to AED, some basic and practical knowledge for survival in the Emergency Department.
A total of 77 participants attended the induction program ( 65 attended the 9th July class and 12 attended the 14th July class (video recording lecture)).
Dr. Ben Wan, the president of the HKSEMS delivered the lecture on general principles in the practice of Emergency Medicine.

EEEM Workshop 2021
The EEEM workshop was conducted on 6th-7th July 2021. The workshop was carried out at the Hong Kong Academy of Medicine in the format of face-to-face physical class. A total of 26 participants took part in the workshop.

Point of care ultrasound course for surgical doctors
The course was held on 31st July 2021 at Prince of Wales Hospital. The course focused on providing guidance for surgical doctors by our experienced A&E fellows. A total of15 participants enrolled in the course.

MMMC (Multi-specialty Medical Mega Conference 2021)
The MMMC is the annual grand event organized by the Association of Private Medical Specialists of Hong Kong, the 11th MMMC was successfully held on 11th - 12th September at Cordis Hotel (Langham Place Mongkok) in hybrid format. The HKSEMS was invited to present in two session: Update on Emergency Medicine and “Mission impossible” in palliative care (in collaboration with the Hong Kong Society of Palliative Medicine)
Group photo of the speakers and Chairperson (from Left to right : Dr. Ho Chung Wing, Dr. Lau Kin Sang, Dr. Wong Oi Fung, Dr. Chen Wai Tsan, Dr. Cheng Wendy and Dr. Ng Sheung Ching, Jeffrey)
Group photo of the speakers and Chairperson (from Left to right : Dr. Chan Ho Yin, Dr. Yang Siu Ming, Dr. Ho Hiu Fai, Dr. Cheung Koon Ho, Dr. Chan Ming Yin)
Dr. Ho Hiu Fai
Dr. Cheung Koon Ho
Dr. Chan Ming Yin
Dr. Wong Oi Fung
Upcoming Events

HKSEMS AGM 2021 on 23th October 2021 ( With annual Dinner)
The AGM of HKSEMS will be held on at 6:00pm on 23th October in HKAM. If you are not able to attend in person, you can sign the attached proxy form and return to the secretariat.
Dinner will be served at the HKAM after the AGM and the conferment ceremony of HKCEM, please join us!!
For details, please refer to the notice below.

ACEM 2021
Save the date !!
The HKSEMS will be the organizer for the 11th ACEM conference.
This is the ASEM’s first ever virtual conference!
Despite the unfavorable COVID 19 situation, our conference will proceed as planned. However, the conference will go virtual in order to protect participants from unnecessary exposure to risk of infection. We hope to connect every EM physician through organizing this great conference.
Further information will be released in Facebook, IG and Twitter soon!
Please stay tune and join us!!
The ACEM 2021 is now open for registration! 
Game changer is a competition for people who wanted to change the world through a game. We are looking forward to innovative ideas that can tackle challenges ahead!! Is that YOU?? Please come and share your ideas with us!!
The ACEM is only four months away- and it is time for us to act. Don’t miss the chance of keeping yourselves up-to-date with the newest evidence on topics presented by our distinguished speakers, sharing your brilliant innovative ideas with your peers in the game changer competition and the chance to meet the exhibitors from various companies!!

Please mark your diary for the following important dates:
30 Sept : Deadline for Abstract submission
15 October: Notification of abstract acceptance
31 October: Early Bird registration deadline
17-19 December: ACEM 2021!!!!!

See you in ACEM 2021!
Members Area Dr Kam Chak Wah
  Emergency Physician in Private Practice
Editor of Emergency Medicine International Journal
Councilor of HKSEMS
From Ultra-ALS to Non-ultimate Omnipotent Emergentist

#1) Emergentology – a Specialty of Breath & Depth
Year 1989 was an extraordinary period full of challenges & attainment. Through the accomplishment with utter endurance of the tremendous stress in the three Membership & Fellowship Exam,
clinical insights were attained as a Diagnostician (Internal Medicine), Hemorrhage & Sepsis Control (Surgery) as well as Holistic Patient Care (A&E).
A&E patients are undifferentiated comprising of any age group, sex and ethnicity. Consequently, we need to provide a complete but focused efficacious approach exemplifying the characteristics of Emergency Medicine as a Specialty of Breath & Depth, wide enough to provide the initial care in a wide spectrum of diseases & sufficiently deep to render not only care to sustain life but therapy whenever feasible with the most affordable resources.
Hence, Resuscitology (Clinical Science of Resuscitation), Emergentology (Clinical Science of Emergency Medical Conditions) & Emergentist (Practice Specialist in this Domain) have been coined in the clinical evolution.
A Higher Exam Chronicle had been produced to create a conducive learning channel to facilitate the Exam PPP(preparation) of the younger doctors to establish a direct path to Emergentist instead of conversion from other streams.
#2)ALS – a Structured & Organized Clinical Management & Communication Format
Year 1992 was another inspiring year after achieving the Instructorship in ACLS, PALS & ATLS in North America before ALS was introduced to HK in 1997. A comparative approach among the ALS systems has enlightened clinicians that the 5 ALS Phases (Primary Assessment + Simultaneous Resuscitation; Secondary Assessment; Transfer & Definitive Management) can be applied to most emergency or critical situations to optimize the patient to maximize the outcome. However, the ALS credential is only an entry instead of exit requirement for Emergentist since the real patient Mx(management) far exceeds the ALS expertise & hence clinical complacence will impair patient’s survival.
#3) The HKSEMS 10th Anniversary – BEST does not exist, always look for BETTER
In the HKSEMS 10th Anniversary Album, the Ultimate Emergency Physician was shaped as a Doctor with an A&E Fellowship Qualification & triply qualified in Cardiac, Paedi & Trauma ALS.
BEST does not exist & we always search for BETTER since the patients’ needs are evolving from adult preponderance to elders coupled with subtle pediatric conditions & high risk pregnancy encompassing life-threatening situations, Acute Ischemic Stroke, ACS & Acute Aortic Syndrome, Substance Abuse & changing modes of trauma. Emergency Skills rapidly develop to include, but not limited to, DAM, USG, advanced anti-dotes, ECMO, REBOA & Visco-elasticity Coagulation interpretation (TEG & ROTEM).
#4) Clinical Medicine – a Quest for Precise & Patient-oriented Tactic within Tremendous Resource Constraint
Emergency admission moderation to help relieve in-patient ward congestion, augmented with Accelerated Mx Pathways such as ACS aim to shorten both the ED Stay & Total LOS in hospital to improve both patient satisfaction & expenditure containment.
Prior to 1997, a group of HK delegates were sent to Oxford of UK to take the first major EBM Course conducted by the God-father, Dr David Sackett & his senior disciples.
The 5 Killer Bs (Biology, Benefit, Burden, Barrier, & Belief – Clinicians & Patients) of new therapy application in the EBM might have contributed to the major Clinical Decision Change from Paternalistic (doctor making the choice for patients), Informed (explained & to choose the best decision from medical perspective) to Shared Clinical Decision (to take the patient’s concern & preference as the important determinants)
#5) The Evolving Frontiers in Emergentology – the Soft & Hard Components
Conventionally, doctors are mainly trained to work independently but highly complex procedures require team work. The soft elements of clinical success factors especially on Communication has emerged as a key factor to prevent errors. CRM, originally named as Air Cabin Crew Resource Management has evolved to Clinical Resources Management to attain the Pre-planned, Effective & SMART Conservation with Mutual Respect, High Risk Alert, Deviation Prevention & Timely Review to achieve the High Reliability Clinical Performance Team.
Emergency doctors at the Clinic Front Door are often summoned when other Specialty Services encounter deficiency. The Prehospital or Overseas Disaster Team, Sports Events, Aeromedics & other Extended Care including Follow-up Clinics, Short-stay Units, Emergency Medicine Wards (Hospitalist option), Toxicology Consultation Services have been established not infrequently with the minimal resources to provide the best return services for both clinical outcome & financial containment, resulting in undue stress to Emergency Doctors.

 #6) Interaction among Clinical Specialties – Trans-disciplinary as a new goal
Since patients are aging & harbor more complex medical conditions, not to mention the highly complex polytrauma, multi-casualty incidents & major disasters. The multi-disciplinary collaboration may not be optimal for the initial care.
  1. Multi-disciplinary means multiple professional groups working together for a common goal but they do not have sufficient understanding of the expertise & limitations of one another. Hence, collaboration can turn out to be chaotic when complicated or critical situation occurs in the absence of a capable leader.  
  2. Inter-disciplinary indicates multiple professional groups working together for a common goal & they have sufficient understanding of the expertise & limitations of one another. However, each group can only provide services within their own expertise.
  3. Trans- disciplinary indicates multiple professional groups working together for a common goal & they have good understanding of the expertise & limitations of one another. Each group can manage the initial life-saving procedures / damage control process in the absence of the immediate input of another specific professional as temporizing measures while awaiting the arrival of the definitive therapists to maximize the patient outcome.
 #7) Prevention is the BEST Rx whenever possible
Despite Operation (or Therapeutics) is the Definitive Rx(treatment) for Trauma (Disease), the Best Rx is Prevention to eliminate suffering, pain, death, disability, mental stress & financial burden. In addition to Secondary Prevention (Damage Control Rx during the acute phase as a Harm Reduction Mx), Emergentist can contribute to Tertiary Prevention (post-injury Counselling when condition optimized or settled) & Primary Prevention ( Community Education, Safe Infrastructure Construction & Legislation).
#8) Paving the Future Path with a Distinct VVM (Values – Vision – Mission)
In the foreseeable future, it is visualized that Emergency Doctor should have a distinct specialty title (such as Emergentist comparable to Radiologist or Anesthetist) to show the uniqueness of the clinical knowledge, skills, attitude & expertise but with sound collaboration with other Specialties to more precisely define the service domains & collaboration.
The multi-facet Emergentists (from Prehospital, ED to EMW) would require a robust, handy & efficient CAD (Computer-assisted Design & Decision) System incorporating Big Data & AI (Artificial Intelligence), hand-held composite Stethoscope / Imaging USG / Multi-function Sensor to expedite precise patient assessment, diagnosis & therapy with a Non-invasive or Minimally Invasive Approach with no pain or only mild pain coupled with the gentle comforting & healing hands of clinicians to allay anxiety by the Human Touch !
Training Professionals, Helping Patients & Saving Lives would re-shape our Clinical Values, Vision & Missions to maximize the Patient Outcome !

Private EM Writes 
Dr Lam, Ka Keung
  Chairman of Private Fellows’ Chapter, HKCEM
Consultant, Hong Kong Baptist Hosptial, 24 Hour Out-patient Clinic
An uncommon complication from minor head injury
We treat head injured patients every day and occasionally manage uncommon complications:
An early 30’s year old lady slipped and fell from bed and had occiput, neck and lower back injuries. The only complaints were severe headache, mild neck and low back pain after injuries. She
had good past health and no known allergy. The mechanism of injury was minor, vital signs and physical examination were totally unremarkable. But the symptom was out of proportion (Pain score 10 out of 10). Immediate computerized tomography of the head revealed no skull fracture and no intracranial bleeding. She was admitted for further care. Blood tests including complete cells counts, liver and renal function tests, random glucose and thyroid function tests were normal. Urinalysis was normal.
The headache persisted despite multiple analgesics given orally and intramuscularly. She kept lying in bed. Repeated neurological examination showed no focal signs. The characteristic of headache was reviewed in detail: the headache got worse when sitting up and immediate relieved when lying down. Condition of postural headache was established and the next step was to confirm traumatic intracranial hypotension. 
Magnetic resonance imaging (MRI) and cerebral angiogram (MRA) of the brain showed diffuse smooth patchy meningeal enhancement, venous distension, decreased mamillopontine distance and narrowing of pontomesencephalic angle, these were radiological features for intracranial hypotension. Subarachnoid hemorrhage and cerebral aneurysm are excluded. Subsequent magnetic resonance myelogram showed thin layer extradural fluid collection along thecal sac along cervical, thoracic and lumbar spine suggestive of cerebrospinal fluid leakage caused by injuries.
Epidural blood patch was performed and she had a good response. She was discharged days after the procedure.
Our department encountered few cases of intracranial hypotension in recent years, all were trauma related and had prompt response to epidural blood patch. Diagnosis requires a high index of clinical suspicion followed by image confirmation. Neurosurgical consultation and arrangement of definitive treatment solve the issue.

Reference: 1. Shah LM, McLean LA, Heibrun ME, Salzman KL. Intracranial Hypotension: Improved MRI Detection with Diagnostic Intracranial Angles. American Journal of Roentgenology 2013;200:400-407.

Coronal T1 MRI brain  with contrast showed diffuse smooth pachymeningeal enhancement in supra- and infra-tentoral brain
The mamillopontine distance was decreased from 75mm  to 39mm compared with  MRI taken 2 years ago.  Cutoff length is 5.5mm.(1)
Pontomesencephic angle is narrowed from 51˚ to 38˚. Cutoff value is 50˚. (1)
Nurse Corner Ms Canmy Chan
  APN, A&E, Tin Shiu Wai Hospital
17 years later
The outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003 shocked Hong Kong and the whole world. It was an unforgettable year to healthcare professionals in Hong Kong since the health care system at that time almost collapsed. SARS caused 1755 infections and 299 deaths, in which 8 of the deceased were healthcare professionals.17 years later in 2020, a brand new and
not entirely understood virus emerged. It spread to a pandemic and Hong Kong was once again affected. As of today, there are 12194 infections and 213 deaths in Hong Kong.
As an AED nurse who has been through both infectious diseases, I noticed that the whole healthcare system in Hong Kong has improved a lot since 2003. In the past, AED only played a passive role in dealing with infectious diseases cases; patients who might be suspected to carry the disease would not receive investigation until after admission. However, during the COVID-19 pandemic, SARS-COV-2 PCR test (Triage and test) is performed on suspected cases even with mild symptoms. This allows patients with mild symptoms to receive test results as soon as possible so that doctors can decide whether to admit or discharge the patients accordingly. Many AEDs, as a result of this arrangement, set up temporary tents as designated areas to hold patients waiting for test results. The bed coordinator staff in the cluster was helpful during this pandemic and helped solve many bed arrangement problems faced by the frontline when there was shortage of bed supply. I very much appreciated the help offered by them.
For the time being, the COVID-19 situation has been under control to certain extent in Hong Kong. AED nurses took up different roles to take care of patients and serve Hong Kong citizens in the past two years. They took the government-chartered repatriation flights to Japan and Wuhan to escort stranded Hong Kong citizens home. They helped take blood and NPS samples from quarantined people at Chung Yeung Estate, They were also deployed to the North Lantau Hospital Hong Kong Infection Control Centre and took part in Universal Community testing programme and Vaccination Programme HK. These provided valuable experience for emergency nurses. The Emergency Nurses Association held an emergency nursing seminar on 18th June 2021. AED nurses from different hospitals were invited to share their experience in AED with others. This let us share our valuable experience with fellow AED nurses.
Finally, there one thing I would like to remind fellow AED nurses: There will be many different challenges ahead of us. We not only need to keep expanding our professional knowledge, but also have to cooperate with each other and face the challenges bravely together.
Advance in EM   Dr. Chau, Cheuk Wai Jeffrey
  Vice-chairman, HBO Subcommittee, HKCEM
Associate Consultant, Hyperbaric Oxygen Therapy Centre, A&E PYNEH
A new Era of Hyperbaric Medicine in Hong Kong
Established in September 2018, the Hyperbaric Oxygen Therapy (“HBOT”) Centre (Fig 1) is the first and the only HBOT Centre in Hong Kong, offering hyperbaric oxygen treatment services to local emergency patients. The centre complies with international standards for hyperbaric facilities, hyperbaric safety and hyperbaric
operations, and is equipped with the latest technology in hyperbaric medicine, such as a hyperbaric chamber capable of treating patients ranging from ambulatory stable ones to those who are highly unstable in an intensive care unit.  
Fig 1. Hyperbaric Oxygen Therapy (HBOT) Centre, PYNEH
Plans for constructing the HBOT Centre began as early as 2013. In view of the prevalence of CO-poisoned patients in Hong Kong, toxicology experts noticed the effectiveness of hyperbaric oxygen in reducing the risk of delayed neurological sequalae1 in such patients and started to explore the possibility of building a hyperbaric chamber in Hong Kong public hospitals. HBOT has been used clinically in many countries for more than 30 years. It has been implemented in hospitals worldwide with proven clinical evidence in effectively treating different types of diseases.
In a cosmopolitan metropolis like Hong Kong, hyperbaric oxygen therapy has been lagging behind for more than 20 years as compared with developed countries like the United States, Australia, United Kingdom, Singapore, Japan and even Taiwan. As a Hong Kong physician, we aim for long-term local development of this technology and hope more patients will be able to benefit from this treatment.
Capabilities of HBOT Centre
The PYNEH’s HBOT Centre is equipped with a triple-lock rectangular hyperbaric chamber (Fig.2) capable of treating both ambulatory and intensive care patients. A rectangular chamber provides a comfortable environment for ambulatory patients to receive treatment; a comfortable environment is important as claustrophobia is one of the significant side effects and contraindications in HBOT. Apart from that, we are also equipped with head-tents as breathing apparatuses for patients instead of breathing masks. Head-tents provide patients with a comfortable breathing environment in view that the treatment duration is usually two hours or longer. They also reduce the rate of compression injury to the face by breathing masks due to pressure changes.
Fig.2 Rectangular Hyperbaric chamber
Moreover, the HBOT Centre can provide treatment for intensive care patients. We are equipped with two hyperbaric compatible mechanical ventilators which are the same brand as those in Intensive Care Units (ICU). They can provide continuous care for patients even in the hyperbaric chamber and reduce the risk of ventilator setting faults due to brand and model differences. The physiological monitor is also essential to ICU patients and we have a hyperbaric compatible physiological monitor which includes all the necessary parameters for use by an ICU. Seeing that unstable ICU patients usually require multiple medications for life support, we have several safe hyperbaric compatible syringe pumps. With all the ICU specific equipment, patients can receive treatment at a level same as that in ICU inside the chamber.
Patients with chronic unhealed wounds, one of the most commonly treated conditions, can be assessed with a transcutaneous oximeter (TCOM) (fig. 3), a unique equipment used to measure the partial pressure of oxygen under the skin, in the HBOT Centre. It can be used to decide whether there is beneficial effect from the treatment of hyperbaric oxygen therapy, and to determine the treatment progress and end-point. The parameter can also act as an objective measurement for the patient to understand the cause and prognosis of his disease.2
Fig.3 Transcutaneous Oximetry (TCOM)
What is Hyperbaric Oxygen Therapy
Hyperbaric Oxygen Therapy involves the treatment of a patient with 100% oxygen under pressure greater 1 atm. The patient is treated inside a hyperbaric chamber by breathing in 100% oxygen through a breathing apparatus. There are both mechanical and physiological effects exerted upon the body through HBOT.3

Mechanically, HBOT provides a pressurized environment which exerts direct effects on bubbles in the body according to different physics laws. Boyle's Law describes the inversely proportionated relation between pressure and volume under a constant temperature. Dalton’s Law states that in a mixture of non-reactive gases, the total pressure exerted is equivalent to the sum of the partial pressures of the individual gases. This is important as under high pressure, we could estimate the amount of oxygen breathed-in according to the maximum pressure achieved. Henry’s Law states that the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid. This is important for estimating how much nitrogen is dissolved in the body during treatment. Gay-Lussac’s Law states that the pressure of a given mass of gas varies directly with the absolute temperature of the gas, when the volume is kept constant. It explains why during pressurization and depressurization, the temperature will change according to the law.4

These physics Laws are especially important for HBOT in treating patients with decompression sickness because the pathophysiology of decompression sickness is based on the nitrogen gas bubbles obstructing different tissues in the body causing different symptoms. The mechanical compression of the bubbles can directly relieve the mechanical obstruction and irritation from body tissues. This can relieve the symptom of decompression sickness very quickly and we can see the clinical effects promptly.5 

Besides the mechanical effects, HBOT will increase the partial pressure of oxygen (paO2) inside the body. The elevation of oxygen partial pressures to 1000-1500mmHg facilitates each of the two processes leading to neovascularization: the growth of new blood vessels from local endothelial cells (angiogenesis), and the recruitment and differentiation in the bed of the wound of circulating stem or progenitor cells to form new vessels. HBOT can ameliorate the inhibited vascularisation in diabetes as well as the mobilization of diminished stem and progenitor cells caused by radiation and chemotherapy.6 

HBOT has been reported to reduce coronary artery stenosis after balloon angioplasty and increase myocardial tissue salvage. Tissue reperfusion is inhibited by the adherence of circulating neutrophils to vascular endothelium.7 Exposure to HBOT causes an inhibition of such adherence that results in a wide range of biological advantages, including improved reperfusion after injury in the brain, heart, lung, liver, muscles and intestines; reduced smoke-induced lung injury and encephalopathy due to CO poisoning; and reperfusion after gas embolism.8

HBOT also exhibits a sharp and direct bactericidal effect upon obligate anaerobic microorganisms. The lack of scavenger enzymes in anaerobic bacteria makes them sensitive to the high concentration in oxygen free radicals. HBOT contributes to the increase in antimicrobial activity and cellular apoptosis.9

Regulating inflammatory molecules has the possible advantage of reducing the extension of injury. Both animal and human researches indicated that HBOT lessens leukocyte sequestration, tumour necrosis factor and interleukin-6; HBOT also helps regulate fibroblast growth factor and collagen synthesis. HBOT has been shown to lead to increased nitric oxide production within the proximity of the wound and to promote increased granulation tissue deposition, epidermal migration and wound closure. HBOT impairs neutrophil adhesion and reduces the inflammatory burden on the chronic wound. 10

Patient treatment statistics in HBOT Centre from October 2018 to June 2021
Based on the UHMS indications, after discussion in the coordination committees invovling different specialties, our HBOT Centre is currently treating patients with both emergency and elective indications. Emergency indications include decompression sickness (DCS), cerebral arterial gas embolism (CAGE), carbon monoxide poisoning (COP), central retinal artery occlusion (CRAO) and necrotising soft tissue infection (NSTI). Elective indications include unhealed chronic wounds, delayed radiation injury and idiopathic sensorineural hearing losses.3

Decompression sickness is diagnosed clinically. The patient typically suffers from muscle or joint pain or other neurological deficit within 24 hours after diving. Once it is suspected, our centre will be consulted and the patient is transferred for hyperbaric treatment. DCS is typically treated by US Navy 6; the condition will mostly improve or subside after one to three hyperbaric treatments.11 There were totally 47 patients consulting us for hyperbaric treatment. A total of 48 treatment sessions were provided and all patients had all their symptoms treated after treatments, except two suffering from Type II decompression sickness. However, they gradually recovered after subsequent follow-up treatments. There were 13 patients with no treatment provided. Reasons included manpower deficit, refusal of treatment by patients, symptoms resolved before treatment and symptom unlikely due to DCS after doctor assessment.

Cerebral arterial gas embolism (CAGE) is mostly of iatrogenic cause and patients usually suffer from severe symptoms such as cardiopulmonary distress or severe neurological deficit. There were 8 CAGE patients treated last year.  These patients required intensive care support and underwent treatment sessions according to their clinical status. Mostly one to three treatments were enough to resolve all bubbles and revert the condition. Time to receive HBOT was the only statistically significant factor predictive of a good outcome with the mean being 8.8 hours.12 One patient who was treated beyond this mean time showed outcome less satisfactory as compared to other patients.

Carbon monoxide poisoning, one of the most frequent methods of suicide in Hong Kong, can be treated by hyperbaric oxygen therapy to reduce the risk of delayed neurological sequalae as a result of the biochemical cascade effect caused by carbon monoxide particles. Increased lipid peroxidation causing nerve damage and reperfusion injury resulting in delayed neurological damage. The Hong Kong Poisoning Information Centre (HKPIC) is responsible for screening the inclusion criteria for COP patients undergoing hyperbaric oxygen therapy. Under the present evidence-based medicine, one to three sessions of HBOT can be performed to reduce the risk of delayed neurological sequalae.1 We have in total 149 consultations, in which a total of 303 sessions were provided for the patients. 57 patients under ICU care required mechanical ventilations. All patients were offered toxicology and psychiatry SOPD follow-ups. However, the default rate was very high for these patients.

Central retinal artery occlusion is an ophthalmological emergency which can cause permanent blindness. Up to now, there is still no effective ophthalmological treatment for this disease and most patients turn blind as time goes by. However, HBOT is proved to be effective especially when treatment of the patient can be commenced within 24 hours.13 After discussion, the Ophthalmology Coordination Committee accepted 6 hours from symptom onset to first consultation with the Hospital Authority’s Accident and Emergency Department or any ophthalmologist as an inclusion criterion. The rationale of HBOT used in CRAO is to buy time in the first few days in order to make the emboli spontaneously dislodge. Thus, our regimen of HBOT for CRAO patients is three to five days’ HBOT treatment following the ophthalmologist’s assessment results and advice. There were 71 patients consulted for CRAO management and a total of 440 treatment sessions were provided. Most of the patients had improvement in visual acuity subjectively from 20 to 70% and objectively of roughly 3 lines of visual acuity. 

Necrotizing soft tissue infection is one of the most severe forms of infection, which can lead to mortality within hours of presentation. Thus, intensive care support as well as surgical intervention to remove the source of infection, is the mainstay of management. HBOT is an adjunctive therapy which enhances bactericidal effects, enhances white cells’ activities, reduces reperfusion injury and enhances wound healing. The number of sessions provided for the patient depends on the severity of sepsis and the needs of inotropic support.14 However, in view that NSTI patients are usually highly unstable and need frequent surgical interventions, transferring patients for HBOT is a big challenge and hurdle for patients to receive this therapy. Thirteen patients were consulted regarding NSTI. Nearly all of the patients needed ICU support in view of this rapidly deteriorating disease. Six out of thirteen patients succumbed despite HBOT treatment.    
Hong Kong has a different disease spectrum from that in other countries. The high incidence of intentional CO poisoning outnumbers most other foreign countries as Hong Kong is a stressful city where psychological illnesses are common. Residential areas in Hong Kong are all minute and it is not difficult for patients to commit suicide by burning charcoal. This can provide us with a significant sample size for studying the true regimen of HBOT for CO Poisoning patients for the prevention of delayed neurological sequalae. To our surprise, the number of CRAO patients does also exceed the original expected patient load. This offers us a good chance to evaluate the actual number for which HBOT treatment sessions should be provided to achieve best results.  

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