Monday, February 18, 2013

Active Travel Bill for better walking and cycling (for Wales)

This is one bill that will pay for itself...

News today that the Welsh Government's "Active Travel Bill" aims to make walking and cycling safer and easier is very welcome news indeed.

This is excellent news!

While still at university I wrote a dissertation on active travel. I would be first to admit that I did focus on England (and Benelux) to an extent. So it's a pleasant surprise to see Wales coming out with legislation.

The medical community, particularly the Royal Colleges which represent the different specialties, need to support this loudly, and not let governments water it down.

Also - why just Wales? Can we expect the Coalition Government to come out with something at least as strong?

Now - let me reproduce the "mission statement" bit of the article:

The Bill, which is a key commitment in the Programme for Government, is aimed at making walking and cycling easier and safer by requiring local authorities to plan fully integrated active travel networks. The legislation will require local authorities in Wales to:
identify and map the network of routes within their areas that are safe and appropriate for walking and cycling;
identify and map the enhancements that would be required to create a fully integrated network for walking and cycling and develop a prioritised list of schemes to deliver the network;
deliver an enhanced network subject to budget availability and following due process;
consider the potential for enhancing walking and cycling provision in the development of new road schemes.

I'm all for high quality segregated infrastructure - and I believe that's the only way we'll get significantly more bums on bikes - but this bit has me worried:

"The legislation will require local authorities in Wales to identify and map the network of routes within their areas that are safe and appropriate for walking and cycling"

My concern here is, if you are riding from A to B on the only realistic route - eg rural A roads such as the A4165 from Oxford to Banbury - and the local authority has not identified that road as "safe and appropriate for walking and cycling", then if you are injured (or worse) by a "careless" or dangerous driver, are they and their insurer going to argue that you shouldn't have been there in the first place?

These concerns are probably ill founded. They state further duties to:

"identify and map the enhancements that would be required to create a fully integrated network for walking and cycling and develop a prioritised list of schemes to deliver the network;"
"deliver an enhanced network subject to budget availability and following due process;"
"consider the potential for enhancing walking and cycling provision in the development of new road schemes."

Therefore it's unlikely an insurer could argue that you shouldn't have been on a particular road, when there is no realistic alternative. I've no great love for vehicular cycling - it's a stop-gap solution for a few fit young cyclists like me - but it looks like it's safe for now.

The further undertakings are vague, but promising. Once there's a document showing the network we SHOULD have, it will become increasingly difficult to put off building it. And the "enhanced network" they mention could be all talk and no tarmac, but could be an example of "aim for the Netherlands, get Denmark" in terms of improving cycling infrastructure.

Most of all, it's nice to see politicians (and others) taking seriously about bikes!

This Bill is a great first step in the right direction; now let's see the rest of Team GB (and Northern Ireland) commit to it, and more.

BNF simplifies advice - today on paracetamol poisoning, tomorrow on..?

Medical guidelines have a habit of becoming more and more complex with time.  

Doctors are quite good at adding complexity to any given situation, but not so good at recognizing when things have become a little too complex to be really useful.  

I can think of any number of examples, even over my career so far.  E.g. when I started out, acutely unwell people were to be given oxygen, and lots of it, to make things easier for their metabolism.  Except some people with COPD (Chronic obstructive pulmonary disease), who shouldn't be given too much oxygen.  Then we find out that one large group of acutely unwell patients - those having a myocardial infarction, acute coronary syndrome or "heart attack" - shouldn't be given lots of oxygen after all, as it might mean a worse outcome for their heart.  Now it seems that oxygen therapy has become so complex, that nurses and other staff are sometimes afraid to give the patient any oxygen at all, for fear of doing the wrong thing.  

Two more examples - hypertension, and type 2 diabetes mellitus - have also undergone this change.  Both these conditions used to be simple to diagnose, and we had a few simple treatments for each.  Now the diagnosis has become complex - with ambulatory blood pressure monitoring for hypertension, and use of HbA1c for T2DM - and the treatments even more so, with many competing drugs offering little in the way of comparative data or data on real-world outcomes.

This is why the latest BNF (British National Formulary) update is so refreshing.  Paracetamol overdose is common, and the guidelines for its management can be hard to follow.  

For example, there were helpful graphs for "high-risk" and "low-risk" patients, showing at what level of paracetamol you should get excited and start giving the antidote, depending on how many hours have elapsed since your patient took the tablets.  

But consider the common case of an overdose taken over a few hours, with perhaps 8g of paracetamol taken the previous night, and another 8g taken the next morning.  How do you plot this patient on the graphs?

Or imagine that you have plotted your patient as being below the threshold ("treatment line"), assuming they are in the "low risk" group.  But if you consider them "high risk", they are over the threshold.  They tell you they didn't have much to eat for a day, maybe two - what will you do with that information?  Are they now "high risk"?

The new guidelines eliminate the old "High risk" and Low risk" categories, drawing a single treatment line and expecting you to use your judgement. I have reproduced the basis for having a single line below:

"Although there is some evidence suggesting that factors such as the use of liver enzyme-inducing drugs (e.g. carbamazepine, efavirenz, nevirapine, phenobarbital, phenytoin, primidone, rifabutin, rifampicin, St John's wort), chronic alcoholism, and starvation may increase the risk of hepatotoxicity, the CHM has advised that these should no longer be used in the assessment of paracetamol toxicity."

New graph:

Old graph:

In addition, they have made the following change:

"For ease of use, recommendations on management have been categorized into:
acute overdose;
'staggered' overdose, uncertain time of overdose, or therapeutic excess"

There then follows clear management plans for each category.  

The BNF should be commended for these changes, which will help clinicians and provide greater confidence in treating this common problem; I hope this represents the start of a realization that "more is not always better", particularly where guidelines are concerned.  

Update: The MHRA Drug Safety Update for this topic is from September 2012 (before I subscribed to their RSS!) and forms the basis for the updated info in the BNF:

I reproduce their summary below:


New simplified guidance on treating paracetamol overdose with intravenous acetylcysteine is now in place. This includes an updated treatment nomogram. The new guidance is as follows:

- All patients with a timed plasma paracetamol level on or above a single treatment line joining points of 100 mg/L at 4 hours and 15 mg/L at 15 hours after ingestion should receive acetylcysteine (Parvolex or generics) based on a new treatment nomogram, regardless of risk factors for hepatotoxicity
- Where there is doubt over the timing of paracetamol ingestion including when ingestion has occurred over a period of one hour or more – ‘staggered overdose’ – acetylcysteine should always be given without delay (the nomogram should not be used)
- Administer the initial dose of acetylcysteine as an infusion over 60 minutes to minimise the risk of common dose-related adverse reactions
- Hypersensitivity is no longer a contraindication to treatment with acetylcysteine

Tuesday, February 12, 2013

This is why you should get better tyres.

Tyres? Tires? Anyway.

Stock tyres - the ones that come with your bike - are rubbish.

They don't get a lot of attention when you're choosing a bike, so manufacturers, dealers, bike shops etc spend the cash on shiny components instead (which attract your attention - chainset, brakes, and rear derailleur, usually). Then they make a saving by using lower spec components where you're less likely to pay attention. Like the tyres.

Yet they're super important, as they make a huge difference to how your bike handles and feels. Good tyres make your bike fast, reliable, and inspire confidence in the corners or in the wet. Poor tyres can drag the whole experience down.

Like these ones.

They're a Kenda 700x23c model, but this isn't to say the whole Kenda range is a dud. Just that these ones weren't very good.

(N.b. you'd usually struggle to buy the same low-end tyres that come with a bike; pretty much all aftermarket tyres are more upmarket. I have had good Kenda tyres in the past).

Several punctures in the first 500km means they're not worth your time or money. This is a common experience with cheap, low-end tyres.

What isn't so common, but was alarming to see with these, was the bulges.

A first look at that photo and you'd think the wheel is out of true. That's what I thought - it's my front wheel, and it's obvious even when riding.

In fact, the tyre has a couple of worrying bulges. Looking closely, there's a zig-zag appearance as it deviates first to one side, then the other.

On inspection both tyres had suffered this, but the front one was worst. Looking inside, the threads were starting to separate from the rubber, and spread - allowing the tube to bulge.

Braking on a descent or taking a corner at speed, this could have meant a nasty blowout, and loss of control. AKA, a crash.

These tyres did no more than 500km, probably less. Commuting and leisure riding, sub-65kg rider. Panniers, occasional shopping, rider and bike never weighing more than 90kg maximum. I've never seen a tyre wear out in so little time.


The solution?

- Check your tyres regularly.
- Bin them before they let you down.
- Consider replacing stock tyres early (you'll enjoy the bike more as a result).

Ironically I have replaced mine with a set of Hutchinson Flash tyres - described here as wearing out and developing an "S Curve". Sounds familiar! Although he did take two Winters on a turbo and one Spring on the open road to achieve that. I'll report back later.