MYTHS IN EMERGENCY MEDICINE

1. MYTHS IN EMERGENCY MEDICINE

2. AIM • Mythology • Common myths • Evidence based practice

3. Mythology • Shared stories that arise and last for generations • Oral initially, then written down • Respond to profound communal needs • Power relations (gods – men, father – son) • Plato and others deployed mythos to support their abstract logos • First physician (Asklepios) mythological son of Apollo

4. Medical Myths • Same communal need based • Specialist - generalist • Based on authoritarian dictates • In the absence of, or contrary to, evidence

5. Selected EM Myths • Analgesia should be withheld in acute abdominal pain, pending assessment • A digital rectal exam should be used in assessment of suspected appendicitis • The Trendelenberg position improves circulation in shocked patients • Atropine should be used before scoline in paediatric intubations

6. Analgesia should be withheld in acute abdominal pain, pending assessmentJUSTIFICATION • In order to diagnose acute abdomen successfully, all clinical signs must be present in their unaltered state • From early 20th century • Cope’s Early Diagnosis of the Acute Abdomen claimed administration of analgesia would delay diagnosis and result in increased morbidity / mortality

7. The evidence • 2 of 17 papers since 1997 • Wolfe, J.M., et al, Am J Emerg Med 22(4):280, July 2004 • DB crossover RCT. • Morphine / NS, or NS / Morphine. • Before and after evaluated by a surgeon & EP, each documenting the presence or absence of six physical signs. • Morphine median decrease in pain 20mm, 0mm with placebo. • No change in six physical findings (rebound, right lower quadrant tenderness, guarding, referred pain, cough pain or position pain) • Overall physical examination changed in 3 of 21 patients after morphine, and 3 of 23 after placebo. • Green, R., et al, Pediatrics 116(4):978. DB,PC,RCT. • Administration of morphine did not reduce the diagnostic confidence of either EPs or surgeons. • EP diagnosis 69% morphine group, 66% controls prior to administration, 70% vs. 71% post-administration. • Surgeon expressed confidence in the diagnosis for 74% of patients in both groups.

8. Bottom Line • There is good evidence that the early ED use of IV morphine reduces acute abdominal pain, without obscuring the diagnosis or changing the treatment.

9. A digital rectal exam should be used in assessment of suspected appendicitisJUSTIFICATION • Rectal examination will be tender in the presence of an inflamed appendix, allowing diagnosis to be made

10. The evidence • Over 20 papers since 1979 • Bonello, J.C., et al, Dis Col & Rect 22(2):97 • DRE in patients subsequently undergoing surgery for presumed appx. n= 495 patients, DRE positive 46% of proven appx. Not appx, 53% positive rectal exams. • Results of rectal exam do not confirm or rule out the diagnosis of acute appendicitis • Dixon, J.M., et al, Br Med J 302(6773):386, 1991 • 1,204 patients main complaint RLQ pain. DRE in 85%. • Nonspecific abdominal pain (38%) acute appendicitis (37%). • All of the patients with appendicitis with rectal tenderness also had positive findings on abdominal examination • DRE did not provide additional diagnostic information if rebound tenderness was evaluated. • DRE made no difference to management plan for any patient. • Manimaran, N., et al, Ann Roy Coll Surg Engl 86:292, July 2004 • Routine DRE has largely been abandoned in the pediatric population but continues to be commonly performed in adults. • Contribution of the DRE to the management of 100 patients with acute abdominal pain. Also assessed patients' perceptions concerning the DRE. • 67% lower abdominal pain. DRE pelvic tenderness in 3, unremarkable in 97. In no case did DRE results prompt a change in the initial diagnosis or management. 78% examination was uncomfortable 19% painful. • Do not support routine performance of a DRE for all adults presenting with acute abdominal pain

11. Bottom line • PR should not form part of the routine examination of RLQ pain: it is uncomfortable, and poorly tolerated. • It has a place when alternative diagnoses are likely. • Should be considered an investigation, not examination

12. The Trendelenberg position improves circulation in shocked patientsJUSTIFICATION • Feet up, head down. • WWI, Walter Cannon suggested use of this for shock treatment. • Increase VR to heart, CO and organ perfusion. • 10 years later, Cannon retracted his support, but no one noticed….

13. The evidence • Taylor Surg Gynae Obstec 1967;124:1005-10 • Shocked vs controls. In 88%, SBP, DBP, MAP all reduced. Lung volumes reduced. • Bivins, H.G., et al, Ann Emerg Med 14(7):641 • RBC radionuclide scanning to determine the effect of the Trendelenburg position on blood volume distribution in ten healthy adult males. • At baseline, 46% of total blood volume was located in the upper body compartment • Blood volume in the upper compartment increased by a median of only 1.8% (range, -1.3% to +/- 4.7%) • Sibbald, W.J., et al, Critical Care Med 7(5):218 • Swan-Ganz measurements in 76 critically ill patients. • Failed to document any consistent beneficial or detrimental effect of the Trendelenburg position

14. Bottom line • Trendlenberg position does not help improve outcome of treatment of shock • May be detrimental on lung volumes and BP

15. Atropine should be used before scoline in paediatric intubationsJUSTIFICATION • Atropine will reduce the risk of bradycardia and asystole induced by laryngoscopy or scoline. • Studies in the OR with multiple doses of scoline suggest bradycardia common.

16. The evidence • Mcauliffe Can J Anaes 1995;42:724-9 • Halothane and succinylcholine anesthesia. No atropine more bradycardia, but episodes resolved spontaneously and without sequelae. • Mirakhur Anaesthesia 1978;33:906-12 • 23 of 25 atropine-treated children experienced persistent tachycardia. • Parnis Anaesth intensive care 1994;22:61-5 • Surveys of anaesthetists in Australia. Most do not routinely premedicate children with atropine but reserve its use for repeated doses of succinylcholine. • Fleming CJEM 2005;7:114-8 • Bradycardia induced by hiccups and defecation resolves spontaneously and is not routinely treated with atropine.

17. Bottom line • There is no evidence to support the use of atropine before emergency intubation of children, using single dose scoline. • It may be harmful: ventricular arrhythmias, loss of protective reflexes and masking of hypoxia related bradycardia.

18. Why do myths persist? • Lack of time to keep up to date with evidence • In EM alone, 800 new English articles a month • Textbooks • How to update? • Teaching styles

19. ABM

20. EBM • Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients." • CEBM

21. How can we use EBM? • Reading journals • Medline searches • Both time consuming, not real time • Look up other people’s work • Critical appraisal topics (CATS) • Best evidence reviews (BETS) • Websites • ebm.bmjjournals.com • www.acpjc.org • www.cebm.net • www.ccme.org • www.bestbets.org

35. Decision making in EM

36. The likelihood that something will happen can be plausibly estimated by how often it has happened in the past

37. Applying Bayesian thinking • What is the likelihood that your patient has the disease in question? • Scores • e.g. Wells’ score for DVT • Low (2%), intermediate (15%), high (35%) • Apply a test appropriately • e.g. D Dimer • Won’t help intermediate group • What is the new likelihood? • Low with negative test – almost 0 • High with positive test – very likely

38. What does this mean? • In EM, we gamble • Make assumptions about the likelihood of the presence of a condition • Apply a test • Increase or decrease that likelihood • Can never say for 100% • Be comfortable with your degree of uncertainty…