Peradine

There's also the perverse incentives in the american medico-legal system: surgeons get sued for not performing surgery, or performing surgery badly, but they rarely get sued for performing 'unnecessary' surgery unless its completely egregious. If the patient has a history/examination which could indicate a need for surgery, and the patient has given informed consent, the surgeon is very unlikely to be succcessfully sued for operating. I'm not implying this is a consious decision on their part, rather a subconscious influence of their training, anecdotes from other surgeons etc.

The problem with that anecdote is that its all with the benefit of hindsight. Certainly, in this instance, non-operative management was appropriate. But the more important question is what on average happens to the entire 'population' of people presenting with Hadfield's symptoms and signs if they're managed operatively and non-operatively.

If we imagine a disease where non-operative management leads to a 50% mortality rate within a year. If we take 100 people with this disease and manage them non-operatively, at the end of a year we'll have 50 people saying how pleased they are to have avoided surgery and complaining about the aggressiveness of surgeons, and we'll have 50 dead people.

That's why the diagnosis and management of disease must be informed by high quality clinical studies, rather than anecdotes.

Look at the graph in figure 2 - the massive overlap in the interquartlie ranges suggests that any differene in the median values can be attributed to random variation within the samples, rather than a true difference in the populations.

Also its better to quote an absolute rather than relative reduction, so the difference is really 3.6%

There's a role for a human-machine hybrid, and indeed there are also quite complicated control systems in work in anaesthesia. As an example, syringe pumps which perform pharmacokinetic calculations: you enter the patient's height, weight, sex, and age, then set a target plasma drug concentration and the pump uses complex pharmacokinetic models to determine how much drug to deliver to acheive that goal and maintain it. I can imagine more elegant systems coming in the future - ie a pump that can adjust drug delivery rates to maintain a given blood pressure. But the overall process of safely delivering an anaesthetic, from pre-operative assessment to post-operative recovery and discharge, is far beyond automating at the moment.

A common comparison is drawn to flying a plane - its a proceduralised and mechanical process for a lot of the time, but occasionally unexpected things happen and you need knowledge and skills to react quickly and prevent serious injury and death. Its like flying a plane but if every plane was built differently with no instruction manual, some of the planes are badly broken before you take off, and someone's trying to repair the engines in mid air.

I'm currently revising for my anaesthetics exams. The things I'm meant to know include:

* The physics and mechanical principles of all the equipment I use, from the ventilator to the pulse oximiter - so that I can identify when and how it might fail and how to respond

* The pharmacokinetics, pharmacodynamics, and mechanism of all the drugs I might use - so I can understand their effects, side-effects, and interactions

* The physiology and function of the human body, including the respiratory, circulatory, neurological, renal, gastrointestinal, musculoskeletal, and immune systems - so I can understand how anaesthesia effects these systems, and how diseases and disorders of the systems will interact with the anaesthetic and how problems can be identified and treated

* The anatomy of the body, with particular focus on the head and neck anatomy to aide in intubation and airway procedures, and neuro-anatomy to aide in regional anaesthetic techniques

* The anatomical, phsiological, and pharmacological consequences of pregnancy, childhood, old-age, and a huge variety of acute and chronic diseases - so I can understand and adapt anaesthetics to these conditions

ICU ventilators are surprisingly complicated machines, we've just brought some HAMILTON-C6 machines at work if you want an idea of the top of the line. Ventilating sick COVID patients, or indeed anyone with ARDS, is one of the most challenging things we do in intensive care. Even with high end commercial ventilators, the mortality rate for intubated COVID patients is >70%.

I would consider the following a bare-minimum feature set for a COVID patient ventilator, any less and it would do more harm than good:

- cycle between an inspiratory and expiratory phase

- during the inspiratory phase, deliver an adjustable volume of gas (in the region of 6 ml per kg of patient's body weight) using as little pressure as possible, with an adjustable upper limit of pressure (in the region of 30 cmH2O)

- during the expiratory phase provide an adjustable pressure against exhalation (in the region of 0-30 cmH2O)

- allow blending of air and oxygen to deliver an adjustable inspired oxygen fraction

- allow the timing of the inspiratory and expiratory phases to be independently varied, thereby allowing the respiratory rate and the ratio of inspiration to expiration time to be controlled. Permit respiratory rates in the range of 8-60 breaths per minute

- measure and display the pressures and volumes within the respiratory system

- allow adjustable alarm-limits for pressures and volumes, and provide clear audible and visual alarms if these values are exceeded

For added patient safety and benefit, the following would be helpful

- measure inspired and expired oxygen and carbon dioxide content, and display both on a continuous waveform graph

- allow the patient to initiate the inspiratory phase by sensing patient inspiratory effort and providing pressure support for inhalation; ie sense when the patient inhales and deliver 10-15 cmH2O pressure for 0.5 seconds to augment inhalation

Doesn't seem to be very helpful - In a multicenter cohort of 302 patients with MERS coronavirus, 92% of patients treated with BiPAP failed this modality and required intubation (Alraddadi 2019)

ICU ventilators are surprisingly complicated machines, we've just brought some HAMILTON-C6 machines at work if you want an idea of the top of the line

I would consider the following a bare-minimum feature set for a COVID patient ventilator, any less and it would do more harm than good:

- cycle between an inspiratory and expiratory phase

- during the inspiratory phase, deliver an adjustable volume of gas (in the region of 6 ml per kg of patient's body weight) using as little pressure as possible, with an adjustable upper limit of pressure (in the region of 30 cmH2O)

- during the expiratory phase provide an adjustable pressure against exhalation (in the region of 0-30 cmH2O)

- allow blending of air and oxygen to deliver an adjustable inspired oxygen fraction

- allow the timing of the inspiratory and expiratory phases to be independently varied, thereby allowing the respiratory rate and the ratio of inspiration to expiration time to be controlled. Permit respiratory rates in the range of 8-60 breaths per minute

- measure and display the pressures and volumes within the respiratory system

- allow adjustable alarm-limits for pressures and volumes, and provide clear audible and visual alarms if these values are exceeded

For added patient safety and benefit, the following would be helpful

- measure inspired and expired oxygen and carbon dioxide content, and display both on a continuous waveform graph

- allow the patient to initiate the inspiratory phase by sensing patient inspiratory effort and providing pressure support for inhalation; ie sense when the patient inhales and deliver 10-15 cmH2O pressure for 0.5 seconds to augment inhalation

I'm an anaesthetics and intensive care trainee, so I know something about ventilation. The reason COVID-19 patients need to get ventilated is due to a failure of oxygenation - the infection causes direct lung injury (ARDS) which impairs oxygen absorption in the lung tissue. Normally we breathe room air, which is 21% oxygen, this drops to around 10% oxygen in the arterial blood due to inefficiencies in the absorption in the lungs. In a normal healthy patient breathing 100% Oxygen, their arterial oxygen content would be around 90%. ARDS significantly impairs oxygen uptake by the lungs, in severe cases patients breathing 100% oxygen may have arterial oxygen concentrations of just 8-10%.

The purpose of ventilation in these severe ARDS patients is to augment oxygenation of the blood, using a combination of techniques including end-expiatory positive pressure and inverse-ratio ventilation, among others, and support the fatiguing respiratory muscles. Because the lungs of COVID-19 patients are already injured by the infection, they are very prone to further ventilator-associated injury. Modern intensive care ventilators have complicated computer-controlled 'modes', which allow precise regulation of ventilatory volumes, pressures, rates, timing, and gas blending. The ARDSnet trials in the early 2000s demonstrated the importance of carefully managed 'lung protective' ventilation, poor quality ventilation is likely to cause further lung injury and make the patient worse, not better. Therefore amateur ventilators are unlikely to be beneficial in COVID-19 unless they can provide similar lung protective ventilation, which would make them quite complicated.

Additionally, ventilation is just one component of the management of sick COVID-19 patients. First you need to pass a breathing tube into their trachea, which is a challenging and risky procedure when performed by a skilled operative in a otherwise well patient, let alone someone on the brink of respiratory failure. Once intubated you will need to keep them deeply sedated, otherwise they will strain against the ventilator and make effective ventilatory care impossible. This requires equipment, drugs, and skilled staff, all of which are going to be in short supply.

I work in the NHS, this is the current user experience

1. Type in user name and password onto computer

2. Logs in to windows, normally taking ~60 seconds, unless you've got the computer where the WiFi signal is poor (yes, WiFi on desktops!) and you get a 'no log in servers'

3. Windows finally loads, click the icon for the software for viewing blood test results

4. An internet explorer window opens, then closes, then after 10 seconds the software opens

5. Type in your username and password, wait 10 seconds

6. Now I want to prescribe some medications, close the first software (computer can't cope with two things open at once), click the logo for the prescribing software

7. A Google Chrome window opens, slowly loads the prescribing software website

8. Type in username and password

9. Navigate through the slow and unintuitive prescribing software

10. Oh wait, I can't prescribe this particular drug without checking a blood test result, close the prescribing software and go to step 4

11. Some alarm goes off, so I have to lock the computer and run. Return from dealing with the alarm, go back to step 1

Google "ECMO walking"

"helpful" may be defined as helpful in preventing the doctor from being sued

That wouldn't be able to detect a heart attack, its to look for atrial fibrillation (AF), which is a long-term abnormality of heart rhythm associated with increased stroke risk

To properly rule out a heart attack you would need

a) A twelve-lead EKG - which requires twelve wires to be connected to specific locations on your body

and

b) Blood tests

Therefore for a consumer-grade device to properly rule out a heart attack it would need to be a large EKG machine with multiple connectors as well as a blood test analysis machine. And that's not even considering that proper analysis of an EKG trace requires a trained medical professional, as the automated traces are notoriously unreliable