Evidenced Based Medicine
Guiding tool for Practice
• I.E. add 40 mg furosemide to HHN Q4h
• Never heard of it? Now what do you do?
1. Call the Doctor?
2. Call your Supervisor?
3. Just do it?
Appraise using JAMA Guide
Evidence-Based Medicine Working Group
• Are the results valid?
• What are the results?
• Will the results help me in patient care?
Types of health care professional
What is the best evidence?
• Friend once told me
• Group of old
• Case series
• Systematic Review
• Case control trial
Levels of Evidence
• The evidence pyramid is
used to illustrate the
evolution of the literature.
• As you move up the
pyramid the amount of
decreases, but …
• increases in its relevance
for application in clinical
What’s Best Evidence?
• Randomized. Prospective, double-blind
trials with control and experimental group
carefully selected to be equal.
• Sufficient sample size
• Low p score < .005
• Above considered Level or Class I evidence
Evidenced Based Medicine
What Are the Steps to the EBM
1. Compose a focused clinical question
2. Conduct a search for evidence
3. Appraise the evidence you find
4. Present and apply your results
5. Evaluate the EBM process and your skill .
Those Which Weaken the
• Small sample size (low n)
• Retrospective studies weaker than
• High p or CI (confidence intervals)
• Physiologic studies weaker than outcome
• A 36 year old patient well known to the ED with
brittle asthma presents with a severe flare-up of her
symptoms that developed over the course of the day.
Her asthma has necessitated admission on three
occasions over the last year and she suffered a life-
threatening attack 3 years ago which necessitated
intubation and ICU, and was associated with the
development of pneumothoraces. She presents today in
marked respiratory distress with significant accessory
muscle use and unable to speak. Her oxygen saturation
was 82% on presentation but has now improved with
supplemental oxygen. She responds only minimally to
initial maximum therapy consisting of continuous
bronchodilators, high dose corticosteroids and IV
magnesium; she appears to be tiring but her pCO2 is 38
mm Hg. The respiratory tech wants to know if she
should call down for the Heliox tank from ICU.
Critical Care Medicine
• You admit a 77 year old female with community
acquired pneumonia to the ICU. She was admitted from
the emergency department with hypoxemia that is
refractory to supplemental oxygen. She is intubated but
this required fiber optic intubation because she could not
be intubated by direct laryngoscopy. She was placed on
antibiotics. She does not have other significant past
medical history. Two days later, her fraction of inspired
oxygen is 40% and she is off positive end expiratory
pressure. You decide she is ready to be extubated but
the critical care fellow expresses concern that she will fail
extubation and will not be able to be reintubated. You
state that you would like to use some diagnostic test to
help predict if she will be successfully extubated. Your
fellow states that the respiratory rate to tidal volume ratio
can be used to predict successful extubation and her
ratio is 50.
• Thick meconium is passed during the delivery of a
term infant. Immediately after birth, the trachea is
intubated and suctioned for copious amounts of
meconium. Despite intensive therapy which includes
mechanical ventilation with pure oxygen and exogenous
surfactant, the infant remains hypoxemic.
Echocardiography confirms the presence of an
anatomically normal heart and is consistent with the
clinical diagnosis of Persistent Pulmonary Hypertension
of the Newborn (PPHN). The resident asks whether to
refer the patient to the Extracorporeal Membrane
Oxygenation (ECMO) team in your tertiary care centre.
You recently read about the benefits of inhaled nitric
oxide and wonder whether this should be tried first.