Letter to the Editor

A concerning trend of synthetic cathinone abuse in Hong Kong

Hong Kong Med J 2023 Dec;29(6):563 | Epub 9 Nov 2023

LETTER TO THE EDITOR

A concerning trend of synthetic cathinone abuse in Hong Kong

HS Leung, MB, BS^1,2; Magdalene HY Tang, PhD^1,2; HF Tong, FHKCPath, FHKAM (Pathology)^1,2; YK Chong, FHKCPath, FHKAM (Pathology)^1,2

¹ Hospital Authority Toxicology Reference Laboratory, Hong Kong SAR, China

² Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong SAR, China

Corresponding author: Dr YK Chong (cyk280a@ha.org.hk)

Full paper in PDF

To the Editor—Synthetic cathinones constitute a class of new psychoactive substances that are derivatives of cathinone, a naturally occurring compound in the khat plant with stimulant properties.1 Historically, our laboratory has encountered a limited number of synthetic cathinone cases. From 2009 to 2017, we identified only seven instances.2 Subsequently, an additional six cases were recorded between 2018 and 2022 (unpublished data, 2022). However, in the first half of 2023 alone, we have identified eight additional cases, seven of which involved intoxication with N,N-dimethylpentylone.

Since its identification in toxicology samples in the United States in 2021, the abuse of N,N-dimethylpentylone has become increasingly prevalent.3 This substance has also been detected in New Zealand and Spain through on-site pill testing, analysis of seized materials, and wastewater-based epidemiological investigations.4 The use and abuse of synthetic cathinones can result in a sympathomimetic toxidrome characterised by agitation, tachycardia, hyperthermia, convulsions, rhabdomyolysis, cardiovascular collapse, and ventricular arrhythmias. N,N-dimethylpentylone has been identified in at least 18 post-mortem forensic toxicology cases.5

N,N-dimethylpentylone has been sold as 3,4-methylenedioxymethamphetamine (MDMA; commonly known as ecstasy). In our experience, co-ingestion of N,N-dimethylpentylone and MDMA is common. Considering the potential morbidity and mortality associated with N,N-dimethylpentylone, the medical profession must remain vigilant in monitoring and describing the toxicological profile of the compound. Importantly, traditional toxicology analyses are often unable to detect new psychoactive substances; specific detection methods are required. When clinicians encounter a suspicious clinical history or unfamiliar/unusually severe clinical toxidromes, they are encouraged to utilise the services provided by our laboratory, including target analyses by liquid chromatography–tandem mass spectrometry.

Author contributions

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

Conflicts of interest

All authors have disclosed no conflicts of interest.

Funding/support

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Paillet-Loilier M, Cesbron A, Le Boisselier R, Bourgine J, Debruyne D. Emerging drugs of abuse: current perspectives on substituted cathinones. Subst Abuse Rehabil 2014;5:37-52. Crossref

2. Tang MH, Hung LY, Lai CK, Ching CK, Mak TW. 9-year review of new psychoactive substance use in Hong Kong: a clinical laboratory perspective. HK J Emerg Med 2019;26:179-85. Crossref

3. Walton S, Fogarty M, Papsun D, Lamb M, Logan B, Krotulski A. N,N-dimethylpentylone—an emerging NPS stimulant of concern in the United States. Toxicol Analy et Clin 2022;34:S67-8. Crossref

4. Rousis N, Bade R, Romero-Sánchez I, et al. Festivals following the easing of COVID-19 restrictions: prevalence of new psychoactive substances and illicit drugs. Environ Int 2023;178:108075. Crossref

5. Fogarty MF, Krotulski AJ, Papsun DM, et al. N,N-dimethylpentylone (dipentylone)—a new synthetic cathinone identified in a postmortem forensic toxicology case series. J Anal Toxicol 2023;47:753-61. Crossref

Cluster of cases of high-dose rosuvastatin–associated rhabdomyolysis and recent reduction of rosuvastatin dose for Asians in other countries

Hong Kong Med J 2023 Oct;29(5):474 | Epub 28 Sep 2023

https://doi.org/10.12809/hkmj2310943

LETTER TO THE EDITOR

Cluster of cases of high-dose rosuvastatin–associated rhabdomyolysis and recent reduction of rosuvastatin dose for Asians in other countries

ML Tse, FHKAM (Emergency Medicine)

Hong Kong Poison Information Centre, Hospital Authority, Hong Kong SAR, China

Corresponding author: Dr ML Tse (tseml@ha.org.hk)

Full paper in PDF

To the Editor—From July 2022 to April 2023, the Hong Kong Poison Information Centre has recorded six cases of severe rhabdomyolysis associated with prescription of high-dose rosuvastatin (≥40 mg daily). All patients were Chinese and presented with a mean creatine kinase concentration of approximately 15 000 IU/L. All except one patient developed acute kidney injury and three required temporary renal replacement therapy. Concomitant liver injury was also evident in three patients. Although statin treatment is associated with development of rhabdomyolysis, the reported incidence is rare at 0.44 per 10 000 person-years.1 Nonetheless Asian patients possess pharmacogenetic factors placing them at high risk. It has been reported that Chinese subjects had a plasma rosuvastatin level 2.3 times that of white subjects, despite being prescribed the same dose.2 Other risk factors include advanced age, hypothyroidism, alcohol abuse, poor renal function, vitamin D deficiency, diabetes mellitus, and drug-drug interactions. The recent clustering of six cases raised concerns about the safety of high-dose rosuvastatin in the Hong Kong population.

In mainland China, the recommended maximum daily dose of rosuvastatin is only 20 mg. It should also be noted that when product inserts of Crestor (rosuvastatin calcium) were revised in 2022 in the United Kingdom,3 Australia4 and Canada,5 Asian ethnicity was a contraindication for prescription of Crestor 40 mg per day. Both prescribers and pharmacists should be aware of this change and doctors should be warned of the increased vulnerability of Chinese and other Asian patients. The licenced dose of rosuvastatin in Hong Kong may need to be revised urgently.

Author contributions

The author had full access to the data, contributed to the study, approved the final version for publication, and takes responsibility for its accuracy and integrity.

Conflicts of interest

The author has disclosed no conflicts of interest.

Funding/support

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Graham DJ, Staffa JA, Shatin D, et al. Incidence of hospitalized rhabdomyolysis in patients treated with lipid-lowering drugs. JAMA 2004;292:2585-90. Crossref

2. Lee E, Ryan S, Birmingham B, et al. Rosuvastatin pharmacokinetics and pharmacogenetics in white and Asian subjects residing in the same environment. Clin Pharmacol Ther 2005;78:330-41. Crossref

3. Crestor film-coated tablets (package insert). London: AstraZeneca UK Ltd; 2022.

4. Crestor (rosuvastatin calcium) film-coated tablets (package insert). Chatswood: Menarini Australia Pty Ltd; 2022.

5. Crestor (rosuvastatin calcium tablets) [package insert]. Mississauga: AstraZeneca Canada Inc; 2022.

COVID-19: evidence for 2-week versus 3-week quarantine

Hong Kong Med J 2023 Jun;29(3):273–4

https://doi.org/10.12809/hkmj209254

LETTER TO THE EDITOR

COVID-19: evidence for 2-week versus 3-week quarantine

KL Hon, MB, BS, MD^1,2; Karen KY Leung, MB, BS, MRCPCH¹; Maggie Wang, PhD³; S Zhao, PhD³

¹ Department of Paediatrics and Adolescent Medicine, Hong Kong Children’s Hospital, Hong Kong SAR, China

² Department of Paediatrics, CUHK Medical Centre, The Chinese University of Hong Kong, Hong Kong SAR, China

³ The Jockey Club School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China

Corresponding author: Dr KL Hon (ehon@hotmail.com)

Full paper in PDF

To the Editor—A new variant of coronavirus disease 2019 (COVID-19, SARS-CoV-2 VUI 202012/01) was identified in the United Kingdom before Christmas 2020. Preliminary reports suggested that this variant was up to 70% more transmissible compared with previous strains in circulation.1 In response, large parts of London and South East England introduced the strictest Tier 4 restrictions, where all residents were asked to remain at home, all non-essential shops closed and Christmas celebrations cancelled for many families in the country.2 This new variant had already been identified in other countries across Europe and beyond (including Australia, Japan and Canada).1 3 The Hong Kong SAR Government swiftly responded by escalating quarantine requirements for inbound travellers from 14 to 21 days, one of the strictest quarantine policies around the world (Table 1 4 5 6 7). It is important to examine the scientific evidence for the effectiveness of quarantine practices to reassure citizens, government officials, and law enforcing personnel.

Table 1. Coronavirus disease 2019 (COVID-19) quarantine duration and COVID-19 testing policies of different places

To compare the effectiveness of various quarantine protocols, a study focusing on infected individuals and the probability of ‘missing’ such cases under each protocol based on the evidence available has been conducted (Table 2).8 Serial testing on days 7 and 14 appeared to be the most effective with 91% of infected individuals identified. On the contrary, the yield was unsatisfactory for serial testing on days 1 and 14 or 21 with a substantial proportion of positive cases missed (43% and 67%, respectively).

Table 2. Theoretical infected cases missed8

Nonetheless the likelihood of COVID-19 transmission is not evenly distributed along the timeline post infection. By applying the known epidemiological characteristics of COVID-19 transmission (ie, transmission follows a gamma distribution with mean=5.3 days, standard deviation=2.1 days, and basic reproduction number=2.5), we can infer the effectiveness of different quarantine durations. For example, an infected individual who has two serially negative reverse transcription polymerase chain reaction (RT-PCR) tests 1 week apart who is released on day 7 post-infection would cause infection in around 0.092 secondary cases (2.5×19%×19.3%). In a second scenario, an infected person with two serially negative RT-PCR tests 2 weeks apart who is released on day 14 post-infection would lead to 0.001 secondary cases (2.5×43%×0.1%). In a third scenario that reflects the latest quarantine changes, an infected individual with two serially negative RT-PCR tests 3 weeks apart and who is released on day 21 post-infection would lead to approximately 0.000 secondary cases (2.5×67%×0.0%). Clearly, the largest reduction in risk of secondary cases due to imported seed cases can be achieved through the 2-week policy rather than a 1-week policy of isolation (99% reduction in risk of secondary cases).

Based on this evidence, it can be concluded that a protocol of 2 weeks quarantine, not 3, will miss one infected person for every 1000 infected persons. Over 8000 reported cases (8425) have been identified in Hong Kong to date and the majority were not quarantined at the time of writing in early 2021. If we apply the policy of quarantine for 2 weeks with two serial tests, we would have missed eight infected individuals who would have been identified over the last 12 months had they been quarantined for 21 days.

Based on scientific evidence, the policy of 3-week quarantine can potentially reduce the risk of introducing this new highly contagious variant. This strict quarantine policy will come with a very high economic cost, but was considered as essential to protect the lives of Hong Kong citizens during the middle of the COVID-19 pandemic in December 2020. In hindsight, our observation provides important information to guide quarantine policy about emerging respiratory viral infections with similar infectivity, basic (and initial) reproduction number R₀ (R-naught), and the current reproduction number R_t (R at time t).

Author contributions

All authors contributed to the concept or design, acquisition of data, analysis or interpretation of data, drafting of the manuscript, and critical revision of the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

Conflicts of interest

As an editor of the journal, KL Hon was not involved in the peer review process. Other authors have no conflicts of interest to disclose.

Funding/support

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. World Health Organization. SARS-CoV-2 Variant–United Kingdom of Great Britain and Northern Ireland. 2020. Available from: https://www.who.int/emergencies/disease-outbreak-news/item/2020-DON304. Accessed 28 Dec 2020.

2. ABC News. London to go into strictest restrictions as new variant of COVID-19 identified. Available from: https://www.abc.net.au/news/2020-12-15/london-to-get-into-strictest-restrictions-highest-covid-rate/12973596. Accessed 28 Dec 2020.

3. BBC News. Coronavirus: cases of new variant appear worldwide. Available from: https://www.bbc.com/news/world-europe-55452262. Accessed 28 Dec 2020.

4. Hong Kong SAR Government. Quarantine for inbound travellers–frequently asked questions. Available from: https://www.coronavirus.gov.hk/eng/inbound-travel-faq.html#FAQ7. Accessed 28 Dec 2020.

5. United Kingdom Government. Entering the UK. 2020. Available from: https://www.gov.uk/uk-border-control/ending-self-isolation-early-through-test-to-release. Accessed 27 Dec 2020.

6. Government of Canada. Travel restrictions in Canada. Mandatory isolation or quarantine. Available from: https://travel.gc.ca/travel-covid/travel-restrictions/isolation. Accessed 27 Dec 2020.

7. Department of Health, Australian Government. Coronavirus (COVID-19) advice for international travellers. Available from: https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/coronavirus-covid-19-restrictions/coronavirus-covid-19-advice-for-international-travellers. Accessed 27 Dec 2020.

8. Kucirka LM, Lauer SA, Laeyendecker O, Boon D, Lessler J. Variation in false-negative rate of reverse transcriptase polymerase chain reaction–based SARS-CoV-2 tests by time since exposure. Ann Intern Med 2020;173:262-7. Crossref

COVID-19 in a centenarian, the vaccination, the breakthrough infection, and the third booster dose

Hong Kong Med J 2023 Apr;29(2):181 | Epub 14 Apr 2023

https://doi.org/10.12809/hkmj2210400

LETTER TO THE EDITOR

COVID-19 in a centenarian, the vaccination, the breakthrough infection, and the third booster dose

John SM Leung, MB, BS, FHKAM (Surgery)

Cardiothoracic Surgical Unit, St Paul’s Hospital, Hong Kong SAR, China

Corresponding author: Dr John SM Leung (leungjohnsiuman@gmail.com)

Full paper in PDF

To the Editor—Dr Ellen Tam and her Tuen Mun Hospital colleagues contributed an important study of coronavirus disease 2019 (COVID-19) infection among the older adults1 who are an increasingly large population in Hong Kong. Of particular interest is the higher mortality associated with increasing frailty but not necessarily increasing age. The latter seems to level off after age 90. May I substantiate this observation with the case of a centenarian who was fully vaccinated with two doses of Comirnaty and survived a breakthrough COVID-19 infection before proceeding to receive a third booster vaccination.

A female patient born in December 1920 had vascular dementia that had progressed over 15 years to a level at which she was completely dependent on a carer. She also had recurrent urinary and respiratory tract infections, osteoporosis and persistent bed sores. Echocardiogram revealed concentric left ventricular hypertrophy and diastolic dysfunction. Her clinical frailty score had been >7 for the last 10 years.

Two doses of Comirnaty were administered on the patient on 19 July and 22 August 2021, respectively. On 8 March 2022, while waiting for her third dose (booster), her whole family became infected with COVID-19 (tested positive by rapid antigen test) and developed cough and fever. The patient remained asymptomatic with no fever, cough, shortness of breath or loss of appetite. Family members recovered spontaneously and the patient remained negative on rapid antigen test from 12 March 2022 onwards. The third dose of Comirnaty was given to the patient after a delay of 4 months on 1 July 2022 and was well tolerated. Her severe acute respiratory syndrome coronavirus 2 nucleocapsid and envelope protein antibody titre was >2500 units/μL, well above the measuring capacity of our laboratory equipment.

This case shows how a centenarian with poor clinical frailty score was well protected against symptomatic COVID-19 infection during the height of the most severe wave of infection. Her antibody response after the third dose of Comirnaty was proven to be very high. We do not regularly test antibody level at a population level following vaccination but the level of protection can be seen from data in the official records (Table 2). Although older adults aged over 80 accounted for the great majority of COVID-19 deaths, those who received three doses of vaccine remained well protected with a mortality rate of ≤1%.2 Had this age-group been fully vaccinated, their mortality would have been reduced from 6542 to around 65.

Table. Mortality percentage and number of deaths by age-group and number of doses of the coronavirus disease 2019 (COVID-19) vaccine received in the fifth wave of COVID-192

Kordowitzki3 produced a report of COVID-19 infection in centenarians across various countries. Mortality rate of COVID-19 appeared to peak among octogenarians, as in this Hong Kong study, and showed some decline among those in their 90s. Although there are scanty reports of centenarian survival from COVID-19 infection from China, Germany and France, there has been little mention of the protection afforded by vaccination in this age-group. Genetic and acquired immune factors that favour extreme longevity might also favour immunity against COVID-19 infection.3

I hope the experience of this patient might be of interest to health workers dealing with the oldest section of our population, particularly in overcoming their vaccine hesitancy.

Author contributions

The author contributed to the drafting of the letter and critical revision for important intellectual content. The author approved the final version for publication and takes responsibility for its accuracy and integrity.

Conflicts of interest

The author declared no conflict of interest.

References

1. Tam EM, Kwan YK, Ng YY, Yam PW. Clinical course and mortality in older patients with COVID-19: a clusterbased study in Hong Kong. Hong Kong Med J 2022;28:215-22 Crossref

2. Hong Kong SAR Government. Archive of statistics on 5th wave of COVID-19. Available from: https://www.coronavirus.gov.hk/eng/5th-wave-statistics.html#. Accessed 20 Jul 2022.

3. Kordowitzki P. Centenarians and COVID-19: is there a link between longevity and better immune defense? Gerontology 2022;68:556-7. Crossref

Better preparation for intubation

Hong Kong Med J 2023 Apr;29(2):178–80 | Epub 12 Apr 2023

https://doi.org/10.12809/hkmj2210571

LETTERS TO THE EDITOR

Better preparation for intubation

Daniel KK Ng, MB, BS, MD¹; Cynthia Cheung²; WY Wu, MNurs³

¹ Department of Paediatrics, Hong Kong Sanatorium & Hospital, Hong Kong SAR, China

² Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong SAR, China

³ Research Department, Hong Kong Sanatorium & Hospital, Hong Kong SAR, China

Corresponding author: Dr Daniel KK Ng (daniel.kk.ng@hksh.com)

Full paper in PDF

To the Editor—We read with interest the article by Cheng et al1 who reported a child with peritonsillar abscess and impending airway obstruction who underwent two failed attempts at intubation with consequent rapid desaturation down to an oxygen saturation (SpO₂) level of 50% to 60%, requiring insertion of a laryngeal mask to maintain ventilation before successful intubation. In the same issue, a standard protocol for intubation was suggested by Leung et al.2 They describe the rescue plan for intubation, alluding to the need for pre-oxygenation for 3 to 5 minutes prior to rapid sequence induction. These articles highlight the need to increase the arterial oxygen reserve to avoid rapid desaturation with all its dire consequences.

We would like to remind readers about a recent technological development that enables measurement and monitoring of the oxygen reserve index (ORI), the increase in arterial oxygen pressure (PaO₂) in real time. As shown by the oxygen dissociation curve, desaturation would be delayed if PaO₂ could be increased from 100 mmHg to say 200 mmHg.3 Oxygen reserve index is a proprietary technology available using the Masimo pulse oximeter with a range from 0 to 1. When SpO₂ reaches 100%, any further increase is reflected in the ORI that will rise above 0. We suggest that attending doctors pre-oxygenate to an ORI well above 0 to achieve a greater oxygen reserve and prevent the rapid desaturation reported by Cheng et al.1 We also suggest provision of pre-oxygenation via heated humidified high-flow (HHHF) oxygen with fraction of inspired oxygen (FiO₂) up to 1. Nonetheless, the other end of the spectrum to hypoxaemia is hyperoxia, less obviously harmful but still to be avoided with excessive oxygenation leading to atelectasis.4 5 To prevent severe hyperoxia, ORI should be maintained at around 0.5. Monitoring the ORI and titrating FiO₂ such that the ORI is maintained above 0 may help prevent both a hypoxic state during intubation and hyperoxia. During intubation, ORI should also be continuously monitored along with SpO₂ since it can predict a decline in SpO₂.

Pre-oxygenation by HHHF followed by continuous HHHF during intubation is also beneficial, even in the presence of paralysis that occurs during rapid sequence induction. Continuous removal of oxygen by red blood cells flowing through the capillaries abutting the alveoli leads to a negative pressure that draws in air from the atmosphere only if the whole airway is patent. This phenomenon is called apnoea oxygenation.6 Nonetheless classic apnoeic oxygenation in the absence of high flow provides little clearance of carbon dioxide and may lead to progressive respiratory acidosis. The impact of adding high flow on CO₂ clearance is controversial, with CO₂ rising at a much lower rate of 0.15 kPa/min in adults6 compared with only classic apnoeic oxygenation and a reported rate of 0.45 kPa/min.7 Nonetheless CO₂ clearance is reported to be lower in children at 0.32 kPa/min.8 In a single case report, the end-tidal CO₂ was reported to be only 9.1 kPa at the end of apnoea of 46 minutes, much lower than the expected rise to >10 kPa in the absence of ventilation.9 Fortunately, PaCO₂ up to 13.3 kPa is not reported to be associated with adverse outcome.10 Continuing HHHF during intubation not only facilitates oxygenation, but it also potentially improves CO₂ clearance by flushing of the dead space, hence lowering the risk of CO₂ toxicity.6 Since HHHF can be administered during intubation without obstructing the procedure, its use should be continued during the intubation process.

Leung et al2 also mentioned cricoid pressure as an essential step in rapid sequence induction although recent evidence has cast doubt on its effectiveness in preventing aspiration and the potential distortion of anatomy making intubation more difficult.11 We suggest that cricoid pressure be applied only if deemed essential by the attending team. It should not be performed routinely during rapid sequence induction.

In conclusion, administration of HHHF with enriched oxygen should be incorporated into the standard protocol for pre-oxygenation and used continuously during intubation. Oxygen reserve index should be continuously monitored to achieve mild hyperoxia to prevent rapid desaturation by a timely increase of FiO₂ or flow or chin lift/jaw thrust to establish upper airway patency. This index is also useful to avoid severe hyperoxia and consequent atelectasis.

Author contributions

All authors contributed to the drafting of the letter and critical revision for important intellectual content. All authors approved the final version for publication and take responsibility for its accuracy and integrity.

Conflicts of interest

The authors have no conflicts of interest to disclose.

Funding/support

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Cheng GC, Wong JW. Managing limitations of the LMA Classic laryngeal mask as a conduit for tracheal intubation in impending paediatric airway obstruction: a case report. Hong Kong Med J 2022;28:321-3. Crossref

2. Leung KK, Ku SW, Fung RC, et al. Airway management in children with COVID-19. Hong Kong Med J 2022;28:315-20. Crossref

3. Scheeren TW, Belda FJ, Perel A. The oxygen reserve index (ORI): a new tool to monitor oxygen therapy. J Clin Monit Comput 2018;32:379-89. Crossref

4. Koo CH, Park EY, Lee SY, Ryu JH. The effects of intraoperative inspired oxygen fraction on postoperative pulmonary parameters in patients with general anaesthesia: a systemic review and meta-analysis. J Clin Med 2019;8:583. Crossref

5. Staehr-Rye AK, Meyhoff CS, Scheffenbichler FT, et al. High intraoperative inspiratory oxygen fraction and risk of major respiratory complications. Br J Anaesth 2017;119:140-9. Crossref

6. Patel A, Nouraei SA. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways. Anaesthesia 2015;70:323-9. Crossref

7. Frumin MJ, Epstein RM, Cohen G. Apneic oxygenation in man. Anesthesiology 1959;20:789-98. Crossref

8. Humphreys S, Rosen D, Housden T, Taylor J, Schibler A. Nasal high-flow oxygen delivery in children with abnormal airways. Pediatr Anaesth 2017;27:616-20. Crossref

9. Ng LY, Chan AK, Lam TW. The use of high-flow nasal oxygen during airway management in a child with epidermolysis bullosa dystrophica and a difficult airway. Anaesth Rep 2019;7:96-9. Crossref

10. Cheng Q, Zhang J, Wang H, Zhang R, Yue Y, Li L. Effect of acute hypercapnia on outcomes and predictive factors for complications among patients receiving bronchoscopic interventions under general anesthesia. PLoS One 2015;10:e0130771. Crossref

11. Erley CL. Cricoid pressure during induction for tracheal intubation in critically ill children: a report from National Emergency Airway Registry for Children. J Emerg Med 2018;55:737. Crossref

Authors' reply

Karen KY Leung, MB, BS, MRCPCH¹; SW Ku, MB, BS, MRCP¹; Ronald CM Fung, MB, ChB, MRCPCH¹; WF Hui, MB, ChB, MRCPCH¹; CC Au, MB, BS, MRCPCH¹; WL Cheung, MB, BS, MRCPCH¹; WH Szeto, BNurs, MNurs¹; Jeff CP Wong, MB, BS, MRCPCH¹; KF Kwan, MB, BS, MRCP (Irel)²; KL Hon, MB, BS, MD¹

¹ Paediatric Intensive Care Unit, Department of Paediatrics and Adolescent Medicine, Hong Kong Children’s Hospital, Hong Kong SAR, China

² Department of Paediatrics and Adolescent Medicine, Hong Kong Children’s Hospital, Hong Kong SAR, China

Corresponding author: Dr KL Hon (ehon@hotmail.com)

We thank the authors for pointing out the importance of increasing arterial oxygen reserve to avoid rapid desaturation with all its dire consequences.1 In this regard, we would like to address aspects related to intubation, oxygenation, ventilation and perfusion.

This is even more important in conditions such as status asthmaticus, raised intracranial pressure, and pulmonary hypertension. In these scenarios, rapid sequence intubation might be a misnomer. The patient should be allowed an adequate period of 3 to 5 minutes of pre-oxygenation to prevent desaturation during the intubation process.2 3

The oxygen reserve index is a great suggestion if oximeter with this function is available. In an emergency, ensuring oxygen saturation remains well above 90% may be the most we can achieve before attempting intubation with an endotracheal tube or laryngeal mask airway. During an emergency, most of us will probably rely on hearing the beeping and seeing the screen of the oxygen saturation monitor instead of carefully oxygenating until oxygen reserve index is above 0.5.

Understanding the oxygen saturation curve, the pressure-volume curve, and the pathophysiology of hypoxaemia and ventilation/perfusion mismatch is another fundamental mental process that care providers must continuously go through even during the critical moment of resuscitation, with atelectatic shunting and dead-space ventilation being problems at the two extremes of the pressure-volume curve. The concept of ventilation/perfusion mismatch leading to hypoxaemia is fundamental, with overdistention leading to dead-space ventilation as in critical asthma syndrome and collapse or atelectasis leading to shunting in collapse of a large segment of the lung (Fig).4

Figure. Concept of ventilation-perfusion mismatch resulting in hypoxaemia

Issues with hypercapnia and hypocapnia are also important in cardiac and cerebral pathologies, and we agree with the authors’ comments about CO₂ clearance. Continuous monitoring of arterial CO₂ partial pressure and end-tidal CO₂ prior to securing an airway in an emergency remains challenging and may be impossible.

Last, in emergency situations, the use of a laryngeal mask airway and the use of video laryngoscopes to improve glottic visualisation are all important routine methods to avoid hypoxaemia and ensure good oxygenation during emergency resuscitation.

Author contributions

Concept or design: KL Hon.
Acquisition of data: KL Hon, KKY Leung.
Analysis or interpretation of data: KL Hon, KKY Leung.
Drafting of the reply: KL Hon, KKY Leung.
Critical revision of the reply for important intellectual content: All authors.

All authors had full access to the data, contributed to the reply, approved the final version for publication, and take responsibility for its accuracy and integrity.

Conflicts of interest

As an editor of the journal, KL Hon was excluded from the review process for this reply. Other authors have disclosed no conflicts of interest.

Funding/support

This reply received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Ng D, Cheung C, Wu WY. Better preparation for intubation. Hong Kong Med J 2023;29:178-9. Crossref

2. Mace SE. Challenges and advances in intubation: rapid sequence intubation. Emerg Med Clin North Am 2008;26:1043-68. Crossref

3. Leung KK, Ku SW, Fung RC, et al. Airway management in children with COVID-19. Hong Kong Med J 2022;28:315-20. Crossref

4. Hon KL, Leung AK. Medications and recent patents for status asthmaticus in children. Recent Pat Inflamm Allergy Drug Discov 2017;11:12-21. Crossref

Suggestions to minimise hesitancy and promote vaccination of children in Hong Kong

Hong Kong Med J 2023 Feb;29(1):86 | Epub 6 Jan 2023

https://doi.org/10.12809/hkmj2210487

LETTER TO THE EDITOR

Suggestions to minimise hesitancy and promote vaccination of children in Hong Kong

Jeffrey Chan¹; KS Ng, PhD²; Benny YC Hon, PhD^3,4; Simon C Lam, PhD, RN⁵

¹ King George V School, Hong Kong

² Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong

³ Department of Mathematics, City University of Hong Kong, Hong Kong

⁴ Department of Psychology, The University of Science and Technology of China, Hefei, China

⁵ School of Nursing, Tung Wah College, Hong Kong

Corresponding author: Prof Simon C Lam (simlc@alumni.cuhk.net)

Full paper in PDF

To the Editor—Coronavirus disease 2019 (COVID-19) vaccine hesitancy was high initially1 but persists in Hong Kong. As of 2 January 2023, 93.0% and 83.3% of the population had received the second and third doses of the COVID-19 vaccine, respectively.2 However, vaccination uptake for the third dose was only 77.06% for age-group of 12-19 years and 30.92% for those aged 3-11 years.2 The government intends to lower the vaccine pass age limit to 5 years and allow schools to hold full-day face-to-face classes only if 90% of students have received three doses of vaccine before 1 November 2022. According to one study,3 there are four reasons for parental vaccine refusal: religious beliefs, personal beliefs or philosophical reasons, safety concerns, and a desire for more information from healthcare providers. Clearly the reason for the low vaccination rate in Hong Kong is mainly due to safety concerns. The Centre for Health Protection of the Department of Health publishes public health recommendations for the Hong Kong Childhood Immunisation Programme. Advised vaccines from birth onwards include Bacillus Calmette-Guérin, hepatitis B, and diphtheria, tetanus, acellular pertussis and inactivated poliovirus vaccines. Although the side-effects of these vaccines, such as low fever, redness, and a sore arm, are well known, parents do not oppose their administration. We recommend that the Department of Health collaborate with the Education Bureau to implement measures that can improve vaccine uptake. These include: provision of more scientific information, educational and on-site vaccination interventions to schools with a low vaccination rate,4 measures to enhance the biological literacy of school children to encourage vaccination, rapid response by healthcare professionals to dispel rumours and conspiracy theories, education of parents about the benefits of vaccination, and provision of educational seminars via Zoom as continued regular education has been shown to improve the success of vaccination programmes.5 In addition, the Centre for Health Protection may consider other options such as delivering a fractional dose to minimise the side-effects. Another study6 suggests that using an intradermal fractional dose (10-20% the amount of the original dose) vaccination using a microneedle patch can result in better immunogenicity. Side-effects are the most common concern among those who are hesitant or opposed to vaccination. As the safety profile of fractional doses is comparable to that of a regular dose,7 fractional dosages may help combat such hesitancy.

Author contributions

All authors contributed to the drafting of the letter and critical revision for important intellectual content. All authors approved the final version for publication, and take responsibility for its accuracy and integrity.

Conflicts of interest

The authors have declared no conflicts of interest.

Funding/support

The work of this letter was supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region (Project No.: CityU 11303521).

References

1. Yu BY, Lam JC, Lam SC, et al. COVID-19 vaccine hesitancy and resistance in an urban Chinese population of Hong Kong: a cross-sectional study. Hum Vaccin Immunother 2022;18:2072144. Crossref

2. Hong Kong SAR Government. Hong Kong vaccination dashboard. Available from: https://www.covidvaccine.gov.hk/en/dashboard. Accessed 2 Jan 2023.

3. McKee C, Bohannon K. Exploring the reasons behind parental refusal of vaccines. J Pediatr Pharmacol Ther 2016;21:104-9. Crossref

4. Gellert P, Bethke N, Seybold J. School-based educational and on-site vaccination intervention among adolescents: study protocol of a cluster randomised controlled trial. BMJ Open 2019;9:e025113. Crossref

5. Akther T, Nur T. A model of factors influencing COVID-19 vaccine acceptance: a synthesis of the theory of reasoned action, conspiracy theory belief, awareness, perceived usefulness, and perceived ease of use. PLoS One 2022;17:e0261869. Crossref

6. Migliore A, Gigliucci G, Di Marzo R, Russo D, Mammucari M. Intradermal vaccination: a potential tool in the battle against the COVID-19 pandemic? Risk Manag Healthc Policy 2021;14:2079-87. Crossref

7. Yang B, Huang X, Gao H, Leung N, Tsang T, Cowling B. Immunogenicity, efficacy, and safety of SARS-CoV-2 vaccine dose fractionation: a systematic review and meta-analysis. BMC Med 2022;20:409. Crossref

Time to take action on filicides in Hong Kong

Hong Kong Med J 2023 Feb;29(1):87

https://doi.org/10.12809/hkmj208986

LETTER TO THE EDITOR

Time to take action on filicides in Hong Kong

KL Hon, MB, BS, MD¹; Karen KY Leung, MB, BS, MRCPCH¹; Celia HY Chan, PhD, MSW²

¹ Department of Paediatrics and Adolescent Medicine, Hong Kong Children’s Hospital, Hong Kong

² Department of Social Work and Social Administration, The University of Hong Kong, Hong Kong

Corresponding author: Dr KL Hon (ehon@hotmail.com)

Full paper in PDF

To the Editor—We previously summarised cases involving filicide in Hong Kong between 2017 and 2018.1 These cases involved children mostly aged <12 years and parents of both sexes with multi-dimensional causal factors.2 Generally, it is crucial to understand the motivation of perpetrators to provide early assessment and intervention. Systematic collection of data on filicide could elucidate these motivations and bring new insights to clinical practice; however, few countries (eg, Australia, Canada) have an official registry on filicide. We recommend setting up an official filicide registry in Hong Kong to investigate the risk factors associated with filicide in Hong Kong in order to inform early assessment and intervention as well as policy decisions. The Comprehensive Child Development Service under Hospital Authority, Department of Health, Social Welfare Department, Education Bureau and Labour and Welfare Bureau aims to identify needs of at-risk children and families in Hong Kong.3

Moreover, depression, related to loneliness, helplessness, or hopelessness, is one psychological condition present in those who committed filicides.2 4 Perpetrators might exhibit help-seeking behaviour or filicidal tendencies. Unfortunately, mental health support in Hong Kong is lacking, especially in terms of caregiver support, although it is no substitute for a strong social support network.1 Physicians may have the opportunity to prevent filicide if these warning signs can be detected.5 We recommend development of a multi-dimensional and systematic screening tool to help healthcare professionals in identifying potential cases for filicide risk.1 Physicians, especially psychiatrists, and other healthcare and social service professionals could seize the opportunity to prevent filicide if early warning signs can be identified.5

Author contributions

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

Conflicts of interest

As an editor of the journal, KL Hon was not involved in the peer review process. Other authors have no conflicts of interest to disclose.

Funding/support

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Hon KL. Dying with parents: an extreme form of child abuse. World J Pediatr 2011;7:266-8. Crossref

2. Tang D, Siu B. Maternal infanticide and filicide in a psychiatric custodial institution in Hong Kong. East Asian Arch Psychiatry 2018;28:139-43.

3. Education Bureau. Comprehensive Child Development Service. Hong Kong SAR Government 2018. Available from: https://www.edb.gov.hk/en/edu-system/preprimary-kindergarten/comprehensive-child-development-service/index.html. Accessed 21 Sep 2022.

4. Hon KL, Chan CH, Chan L. Filicides in Hong Kong. HK J Paediatr (New Series) 2019;24:48-50.

5. Klier CM, Fisher J, Chandra PS, Spinelli M. Filicide research in the twenty-first century. Arch Womens Ment Health 2019;22:135-7. Crossref

Observations of a locum doctor working at the Asia World Expo Community Treatment Facility

Hong Kong Med J 2022;28(6):503 | Epub 25 Oct 2022

https://doi.org/10.12809/hkmj2210252

LETTER TO THE EDITOR

Observations of a locum doctor working at the Asia World Expo Community Treatment Facility

Alexander Chiu, FHKAM (Medicine), FRCP (Edin)

Community Treatment Facility, Asia World Expo, Hong Kong

Corresponding author: Dr Alexander Chiu (subclavian@netvigator.com)

Full paper in PDF

To the Editor—To combat the fifth wave of the coronavirus disease (COVID) pandemic, the Hospital Authority re-opened the Community Treatment Facility at the Asia World Expo (AWE) in January 2022 to help alleviate the burden on hospitals.

Clinical mindset while working at a makeshift hospital requires some modification. For instance, the threshold at which to transfer a deteriorating patient must be lower, since the AWE is not equipped to care for ill patients. For example, there is no piped oxygen supply. Since oxygen cylinders can provide support for only a limited duration when used in high-flow mode, and oxygen concentrators cannot support flow of more than 4 L/min, resuscitation is more difficult at the AWE.1 In the author’s experience, a patient with SaO₂ <94% on room air already warrants serious consideration for transfer to another unit.

The choice of therapeutics such as intravenous antibiotics will depend not only on the patient’s susceptibility but also on ease of use so that workload for nurses is minimised. An antibiotic that can be injected once daily is preferable to a 12-hourly option; and an antibiotic that can be directly injected intravenously is preferable to one that needs pre-dilution with normal saline.

Cough is a prevalent complaint amongst patients attending the treatment facility at the AWE. Chinese herbal medicine provides good symptomatic relief and was welcomed by many patients. For patients with a history of benign prostate hyperplasia, the author will first consult the Chinese Medicine team to establish whether any herbal medicine has the ingredient ephedra alkaloid (麻黃).2 The latter contains ephedrine and may aggravate lower urinary tract symptoms.3 The author learnt from the Chinese Medicine team that the cough remedy “止嗽散合獨參湯加減” contains only a small amount of ephedra, and is safe for use in patients with lower urinary tract symptoms.

Setting up the AWE has been complex with many logistical issues. The administration responsible for the setting up of AWE should be commended for their effort.

Author contributions

Conflicts of interest

The author has disclosed no conflicts of interest.

References

1. Jain R, Sharma C. Oxygen supply in hospitals: requisites in the current pandemic. Anesth Essays Res 2021;15:253-6. Crossref

2. Zhao W, Deng AJ, Du GH, Zhang JL, Li ZH, Qin HL. Chemical constituents of the stems of Ephedra sinica. J Asian Nat Prod Res 2009;11:168-71. Crossref

3. Balyeat RM, Rinkel HJ. Urinary retention due the use of ephedrine. JAMA 1932;98:1545-6. Crossref

Comparison of the pattern of elderly abuse in Hong Kong before and after the COVID-19 pandemic

Hong Kong Med J 2022;28(6):502–3 | Epub 25 Oct 2022

https://doi.org/10.12809/hkmj2210304

LETTER TO THE EDITOR

Comparison of the pattern of elderly abuse in Hong Kong before and after the COVID-19 pandemic

YF Shea, FHKAM (Medicine); Whitney CT Ip, MRCP (UK); James KH Luk, FHKAM (Medicine)

Department of Medicine, Queen Mary Hospital, Hong Kong

Corresponding author: Dr YF Shea (elphashea@gmail.com)

Full paper in PDF

To the Editor—We have previously published our observations on changes to the pattern of elderly abuse in 2020 (during the coronavirus disease 2019 [COVID-19] pandemic) compared with the pre-pandemic period.1 There was a proportionate increase in physical abuse with the spouse as perpetrator. With the publication of additional data by the Social Welfare Department, we have obtained further data relating to elder abuse between 2014 and March 2022 (n=4293).2 We compared data reported during the COVID-19 pandemic from 2020 to March 2022 (n=996) with pre-pandemic data (from 2014 to 2019, n=3297). The abuse methods and identity of perpetrator were compared using Chi squared statistics. The data are summarised in the Table.

Table. Elder abuse data in Hong Kong comparing pandemic (2020-March 2022) with pre-pandemic period (2014-2019)2

There was proportionately more physical abuse (71.6% vs 65.9%, χ²=11.0774, P=0.009) but less financial abuse (8.2% vs 16.2%, χ²=39.4716, P<0.001) during the pandemic compared with the pre-pandemic period. Regarding the perpetrators, there were proportionately more spouses (64.8% vs 54.7%, χ²=31.8566, P<0.001). There was no difference in the pattern of elderly abuse or identity of perpetrators within the COVID-19 pandemic period (ie, 2020 to March 2022).

We continued to observe proportionately more physical abuse with the spouse as perpetrator during the pandemic. It is likely the initially low vaccination uptake among older adults and COVID-19 outbreak meant the older adults were more likely to remain at home. There were insufficient opportunities for recreational activities or social support. A spouse, often the only co-habitee, had more opportunities to inflict abuse. Government and social welfare organisations should be alerted to this change.

Author contributions

Conflicts of interest

As an editor of the journal, JKH Luk was not involved in the peer review process. Other authors have disclosed no conflicts of interest.

Funding/support

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Ip CT, Shea YF, Chan HW, Luk KH. Changes in pattern of elderly abuse during COVID-19 pandemic. Psychogeriatrics 2022;22:286-7. Crossref

2. Social Welfare Department, Hong Kong SAR Government. Services for prevention and handling of elder abuse. 2022. Available from: https://www.swd.gov.hk/en/index/site_pubsvc/page_elderly/sub_csselderly/id_serabuseelder/.Accessed 12 May 2022.

Vitamin D supplementation to prevent COVID-19 in older people

Hong Kong Med J 2022 Oct;28(5):413 | Epub 21 Sep 2022

https://doi.org/10.12809/hkmj2210186

LETTER TO THE EDITOR

Vitamin D supplementation to prevent COVID-19 in older people

Timothy Kwok

Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong

Corresponding author: Prof Timothy Kwok (tkwok@cuhk.edu.hk)

Full paper in PDF

To the Editor—Since the review on the immune modulating effects of vitamin D in coronavirus disease 2019 (COVID-19) infection by Kaler et al1 last year, there has been an open-label trial showing positive effects of vitamin D supplementation in COVID-19 patients in Spain. Out of 838 COVID-19 in patients, 447 were routinely given calcifediol (25-hydroxycholecalciferol) 532 μg on admission, and 266 μg on day 3,7,15 and 30. The treatment group had very significantly lower rates of intensive care unit admission (4.5% vs 21%) and death (4.7% vs 15.9%).2 In contrast, two randomised trials of a single large dose of vitamin D3 on admission in moderate to severe COVID-19 patients have showed no significant benefits.3 The discrepant results may be due to differences in vitamin D formulations. As compared with vitamin D3, calcifediol does not require hydroxylation in liver which is often impaired in acute illness. Therefore, vitamin D supplementation should preferably be started before exposure to COVID-19. Older people who seldom go outside, especially those in old age homes, have high prevalence of vitamin D deficiency. Indeed, an expert group recommended routine use of vitamin D3 1000 units daily in old age homes.4 A randomised trial of vitamin D3 in older people showed that doses up to 2000 units daily for four months was very safe.5 In the midst of the pandemic, I recommend vitamin D3 2000 units once daily in homebound older people to prevent COVID-19 infection and its complications, especially those who are not fully vaccinated.

Author contributions

The author contributed to the Letter, approved the final version for publication, and takes responsibility for its accuracy and integrity.

Conflicts of interest

The author has disclosed no conflicts of interest.

Funding/support

This Letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References

1. Kaler J, Hussain A, Azim D, Ali S, Nasim S. Optimising vitamin D levels in patients with COVID-19. Hong Kong Med J 2021;27:154-6.Crossref

2. Nogues X, Ovejero D, Pineda-Moncusí M, et al. Calcifediol treatment and COVID-19-related outcomes. J Clin Endocrinol Metab 2021;106:e4017-27. Crossref

3. Cannata-Andía JB, Díaz-Sottolano A, Díaz-Sottolano A, et al. A single-oral bolus of 100,000 IU of cholecalciferol at hospital admission did not improve outcomes in the COVID-19 disease: the COVID-VIT-D-a randomised multicentre international clinical trial. BMC Med 2022;20:83. Crossref

4. Rolland Y, de Souto Barreto P, Abellan Van Kan G, et al. Vitamin D supplementation in older adults: searching for specific guidelines in nursing homes. J Nutr Health Aging 2013;17:402-12. Crossref

5. Schwartz JB, Kane L, Bikle D. Response of vitamin D concentration to vitamin d3 administration in older adults without sun exposure: a randomized double-blind trial. J Am Geriatr Soc 2016;64:65-72. Crossref

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