How do doctors learn to prescribe/use drugs in a safe and effective manner? This is no simple question and when the issue of a prescribing habit being regarded as lethal it becomes highly relevant. As I have stated before I do not want to blame the law for its inadequacies in comprehending complex medico-legal issues. From the perspective of the prosecution, it is better to keep things as simple as possible for the Jury. This is why there was such consternation with my original report. I was concerned about the definition of “assumed facts” and relevance to drug dosages.
- The Assumed Facts.
- There are elements of the “assumed facts” in this case that need to be raised. It is not my intention to repeat or summarise the contents of the three expert opinions from Drs Critchely, Mainland and Chan, however there are some factual inconsistences and statements of “fact” that do require more interrogation to assess their validity. I am not stating that factual errors were made deliberately in order to mislead, however I do feel that when making opinions on such serious matters as the death of a patient and the professional life of a doctor, that the nature and quality of the facts on which opinions are based must be of the highest order.
- Let me begin with an example. A simple question.
- What was the height and weight of the patient? These are two “facts” required to assess the morphology of the patient and in particular the Body Mass Index (BMI).
- Relevance of BMI.
- The BMI is a simple calculation using the height and weight of the patient, using a simple formula, kg/m2 where kg is the weight in kilograms and m2 is the height in meters squared.
- With a weight of 113.5 kg (as recorded on the anaesthetic sheet) and a height of 170 cm (as recorded in the autopsy record) the derived BMI is 39.3.
- BMI of 39.3 would place Ms Lee in the category ASA II of the American Society of Anaesthesiologist Physical Status Classification System.
- But what if the pathologist who performed the autopsy was not accurate. What if the “170cm tall” was a false fact? Delving into the available documentation reveals a section from the report from Dr Phoebe-Anne Mainland. In this report there is section (para 22) which details a previous operation on 30th April 2014. The weight and height are detailed; 116.3kg, height 163cm.
- That gives a rather different BMI. However, the problem with the BMI is that it looks at the estimate of body fat and the potential risk factors related to that. The BMI is not regarded as an accurate indication of health in individuals where the weight may be disproportionately related to muscle mass. A good example are athletes. In the case of Ms Lee, she was a professional dance instructor. She loved to dance and danced all the time. Dancing is a physical activity and promotes muscle growth, as in an athlete. It is unfortunate that the autopsy did not look at the relative muscle mass.
- So, whilst we can challenge the relevance of BMI and anaesthetic risk in this case we are focussing on the reliability of the contemporaneous documentation, and hence its interpretation in the process of giving a professional, expert opinion.
- Another very important and relevant point, and here I must acknowledge Dr Mainland for providing a perfect example, is that drug use should not be prescriptive upon specialty but on application.
- In Dr Mainland’s report, para 23 is a section of figures and the ultimate result: tumescent fluid, lignocaine concentration 13.8mg/kg.
- There is global rivalry between dermatologists and plastic surgeons in the field of cosmetic surgery and dispute in the dosage of local anaesthetic agents (lignocaine) used in liposuction. Dr Jeffrey Klein, a reputable American dermatologist recommended a lignocaine level of as high as 55mg/kg when diluted in normal saline (New England Journal of Medicine, Volume 340, Number 19, May 13, 1999, pages 1471 – 75), whilst the plastic surgeons recommended maximum safe level of 7mg/ml when lignocaine is combined with adrenaline.
- 7mg/kg versus 55mg/kg is a big difference and lignocaine can certainly be lethal.
- Klein had established his reputation in the late 80s and published a series of papers describing his emerging experience(J. Klein, 1990)(J. Klein, 1995)(J. A. Klein & Jeske, 2016). His advocacy of the use of large volume of dilute anaesthetic solution with a much higher dosage of lignocaine claims a superior aesthetic result and fewer surgical risks i.e. the use of high dose lignocaine (> 7ml/kg) in liposuction does not put the patient at a higher overall risk, as it reduces the risk of bleeding and allows the use of no or less sedative anaesthesia.
- I have spent some time to discuss this aspect as it does reveal that different specialties do not always share the same understanding of potential risks of medication. In addition, the assumption by one expert that a fact is true may not hold for another expert.”
Let me add to this “reality”, a short anecdote. I trained as a plastic surgeon in the UK. I spent a year as an SHO in Leicester which was a two-Consultant-Unit. Mr Milward and Mr Henderson. Two excellent consultants who had come through the UK training scheme and were both very well trained and widely respected. So how come that in one specific procedure they had completely opposite views? When I was being trained, prominent ear set back was a very common operation performed in the NHS. For common operations the consultant’s objective was to get the juniors to a level of competence as quickly as possible so they did not have to deal with these “minor” procedures. The operation can be performed under local or general anaesthetic. It is quite a complicated procedure, and involves separating the layers of the ear sandwich: skin, cartilage skin. The cartilage is then trimmed and reshaped. Skin is excised and redraped over the cartilage and the wounds closed and bandages applied. Dissecting the layers of the sandwich is a technical exercise which is aided by hydrodissection. This is the injection of fluid under pressure to distend the tissues and begin a separation of the layers. The definitive separation is achieved by using a knife or scissors.
So, what was it that Mr Milward and Mr Henderson did differently? It was the use of lignocaine and adrenaline as the tumescent fluid. Mr Milward always used it. Mr Henderson never used it citing the external ear as an “end organ” the viability of which could be prejudiced by the vasoconstrictive effect of the adrenaline. He insisted normal saline should be used as the tumescent fluid.
What was a junior meant to take away from that? What did I use as my standard practice many years later? It was to use the local anaesthetic with adrenaline. Never a problem.
But what is the relevance of this to a case of GNM in Hong Kong?
Well, it is to do, yet again, with Propofol.