Dr Robert Eager

Not necessarily

Non-medical “facts”

Battle of Hastings :1066

Execution of Charles 1:1649

Occurred Jan 30 1648

Until 1751, year was 25/3 to 24/3

Later histories post 1751 changed it to 1649

Shakespeare and Cervantes died same day

Actually died 10 days apart but in different countries.

1 RCT performed on new intervention. Restricted to defined pt group

2 RCT shows benefit so applied to those in defined grp

3 Unclear if any benefit to those excluded from original RCT. No one looks

4 Years pass. Intervention becomes standard of care and applied broadly

5 General consensus develops that as it is now standard, unethical to study it in other groups as it would involve denying a group(placebo) what has become std care

6 It is now dogma

Systematic reviews include heterogenous groups but combine results

Hides potential problems

Everyone stops looking

Or publication bias sets in

Some one comes up with a logical and reasoned idea that appears to hypothetically make sense. Easy to understand

It is adopted by an authority and emphasised

No one every studies if the logic is correct

More problematically, no one looks to see if it causes any harm.

Examples are Cervical Collar, Golden Hour and ATLS shock classes

Trauma Myths

Glasgow Coma Scale

Cervical Collar

Palpable pulses and relationship to BP

Medical Myths

Calcium Resonium

Non-use of ipsilateral arm post mastectomy

ABG in Pulmonary Embolus

Example of good idea derived from a single cohort of pts

Extrapolated to other groups not originally studied

Resulting in dogma on how to deal with various GCS levels

But as not all GCS 8 scores are equal, the management cannot be equal

Now accepted everywhere as standard treatment where a cervical injury is possible

But NEVER studied

Was designed based on the logical reasoning that less movement means less injury to cord

Design changed over the years but original assumptions never challenged

Epidemiology and predictors of spinal injury in adult major trauma patients: European cohort study

Eur Spine J. 2011 Dec; 20(12): 2174–2180.

Reviewed TARN database from 1988 to 2009

250,584 pts

4489 pts had spinal cord injury (1.8%)

So potentially 98 pts out of 100 may have had a collar on to protect against an injury they didn’t have

But to be on TARN database, must be admitted pt

But lots of patients come into ED with collars on and never admitted

So ratio of pts probably far exceeds 98:2

Collar on but no injury: Collar on and cord injury

Pressure areas

Airway problems

Distraction if OAD injury

Immobilisation for long periods

Do not blindly use

Trauma ≠Collar

If pt GCS 15 and co-operative with no abnormal neurology, consider no collar

If reduced GCS and injury consistent with possible cord injury, use it

BUT

ATLS courses perpetuate the dogma

Conventional wisdom that a palpable radial pulse means that the BP is likely to be > 80mmHg Sys

Lower the BP, then only femoral and carotid until eventually only carotid

Green box: ATLS says BP is Red Dots: the Measured BP

How do you treat hyperkalaemia?

Other things you did worked Low K diet Insulin-dextrose Dialysis If sodium was exchanged for potassium, has this resulted in dilutional effect?

Std advice for rest of life

No blood pressure monitoring

No venipuncture

No IV cannulation

No pinpricks

So what is the evidence?

Rationale

Any injury to arm may result in an inflammatory process and in absence of functioning lymphatic system may result in chronic debilitating lymphoedema

Treatment of established lymphoedema is unsatisfactory

So prevention is better than cure

Halstead in 1921 proposed that post-surgery infection was likely cause of arm swelling post mastectomy

Villasor in 1955: Retrospective review of 79pts after breast

surgery. 3/79 developed lymphoedema post venipuncture so proposed venipuncture to be avoided

Britton and Nelson in 1962: Recurrent cellulitis in 53% of 114 pts who had any

form of injury to arm (cat scratch, thorn prick, insect bites) so stated any injury to arm can result in swelling.

Problem is that evidence for both sides are poor quality ie level studies 4/5

Clark et al 2004: Prospective cohort study concluded that 8/18 pts (44%) that had venipuncture developed swelling compared to 31/170 (18%) pts with no venipuncture. But no randomisation, no control of confounders and did not report when the swelling occurred.

Winge et al 2010: Retrospective study of 311 pts by questionnaire. 88 had venipuncture on affected arm but only 4 developed swelling.

Ferguson at el 2016 J Clin Onc

Bilateral Arm Volume Measurements pre and post op

3,041 measurements over 9 years

Conclusion: “although cellulitis increases risk of lymphedema, ipsilateral blood draws, injections, blood pressure readings, and air travel may not be associated with arm volume increases. “

Canadian Agency for Drugs and Technologies in Health (CAATH) Rapid Response Reports

IV Access for post mastectomy pts:

“No relevant systematic reviews, meta-analyses, randomized controlled trials, non-randomized studies, or evidence-based guidelines were identified.”

Cemal et al 2011: Systematic Review “limited evidence to support the recommendation

that venipuncture should be avoided in patients with a history of lymph node surgery. Similarly, there is a paucity of evidence to support the preventative measures regarding limb constriction”

“arbitrary recommendations have significant effects on patient care resulting in unnecessary insertion of central catheters (to avoid venipuncture of the affected limb), blood draws from regions not routinely used for this purpose (e.g. external jugular vein, femoral vein, or dorsal foot veins).”

“additional research is clearly required”

Entrenched dogma in staff and patients

An attempt at RCT in NZ was unsuccessful

Evidence against use of arm is poor

Avoid if can but evidence does not support it being absolutely contra-indicated.

Balance risk of lymphoedema vs risk of problem requiring use of arm

A Normal ABG excludes acute PE

Myth based on no evidence

Stein et al, Chest 1996

Conclusion: “Blood gas levels, therefore, are of insufficient discriminant value to permit exclusion of the diagnosis of PE.”

Maloba and Hogg. EMJ 2005

Conclusion of metanalysis: “Arterial blood gas analysis alone is of limited diagnostic utility in suspected PE.”

At least half of what you know now is probably wrong

But you don’t know which half

Standard care is not always correct and will change over your career

Question why things are done especially when you are told “it’s always done this way”

Always have a healthy scepticism

If appears to be dogma, to enquire and discuss is good. Blind acceptance is wrong