Tuesday, September 22, 2009

Common Mnemonics and Formula in Emergency Medicine

Updated 29 Aug 2012
Note: This post is going to be updated from time to time as I re-collect back as many mnemonics and study tips as possible. I ask if you can help to contribute any mnemonics you may want to share with me, as well as to give your comments to this post. Thanks.
1. A great site with many sets of medical mnemonics for medical students.......and postgrad students too. Click here to access.
2. A searchable database of medical mnemonics including a downloadable pdf format of the entire database. Click here to access.
I have included below here a database of mnemonics commonly used in emergency medicine, at least in the place where I work/lecture in.
Note: This post will be updated regularly as more and more mnemonics be added in:

Pre-hospital Care/First Responder

1. Information to relay to when making an emergency call (mnemonic: ETHANE)

E = Exact Location - The precise location of the incident

T = Type - The nature of the incident (trauma, non-trauma, heart atack, motor-vehicle accident), including how many vehicles, buildings etc. are involved

H = Hazards - Both present and potential (e.g., explosion, spillage of combustible materials, highly volatile hydrocarbons, chemicals, etc)

A = Access - Best route for emergency services to access the site, or obstructions and bottlenecks to avoid

N = Numbers - Numbers of Casualties, Dead and Uninjured on scene

E = Existing Emergency Services - Which services are already on scene, and which others are required - s0 as not to duplicate services, and for better utilization of services in other concurrently emergency happenings.

2. Focused History in Emergency Conditions/Trauma (mnemonic: SAMPLE)

S = signs and symptoms
A = allergies
M = medications
P = pertinent past medical history
L = last oral intake
E = events leading up to.

3. Things to look for in head-to-toe survey for trauma (mnemonic: DCAP - BTLS)

D = deformity
C = contusions
= abrasions
= punctures/penetrations

= burns
= tenderness
= lacerations
= swelling.

4. Signs to suspect fracture (mnemonic: DOTS)

D = Deformity
O = Open Wound
T = Tenderness
S = Swelling
Airway Management
1. The 7"P"s of Rapid Sequence Intubation
1st P = Preparation
- Prepare what?
- Prepare: Patient, Physician, Pharmacology, Proper set of Equipments
- Patient - well connected to monitors, position of table at physician's elbow when flexed 90 deg or umbilical level
- Physician - comfortable position, mask & gown-up
- Pharmacology - for induction LOAD+Scoline for paralyzing agent
(see 3rd P for description of LOAD)
- Equipments: mnemonic - MEALSSS
- M = Mask - well fitting snugly
- E = ETT (appropriate size + 1 size above and 1 size below); for children, ETT size = (age/4) + 4 or child's little finger (less accurate)
- A = Airway gadgets in case of difficult airway or failed airway, e.g. Oropharyngeal airways, surgical airways, Quicktrach, cricothyrodotomy set, LMAs
- L = Laryngoscope blade: Straight (in BM, "L"urus, therefore, Mi"L"ler), "C"urved = Ma"C"intosh; good light source
- S = Syringe to test and inflate cuff balloon of ETT
- S = Stylet
- S = Suction catheter, Yankauer catheter
2nd P = Preoxygenation
Why pre-ox?
Administer FiO2 of as near possible as to 100% for 3 minutes - for denitrogenation, washing out N2 and replace with O2, improve apneic period before desaturation happens to less than 90%
3rd P = Premedications
"LOAD" up patient; basically to reduce risk of "tight brain" and "tight lungs"
- L = Lignocaine - obtund gag reflexes, reduce risk of increased ICP
- O = Opioids - to blunt sympathetic responses
- A = Atropine - to reduce risk of bradycardia esp for children given scoline
- D = Defasciculating dose of competitive NMB - can reduce intensity of fasciculation due to scoline
4th P = Paralysis
About 45 s - 1 min for scoline; about 1 min for Rocuronioum (0.9 -1.0 mg/kg iv)
Placement/passing of ET tube
5th P = Pressure on cricoid cartilage (Protection)
Sellick maneuver - the way to do it, is BURP! on cricoid cartilage
B = Backward
U = Upward
R = Rightward
P = Pressure
Why cricoid cartilage? it is the only structure with complete ring (signet ring shaped) - to press on vertebral body of C6
6th P = Placement of ET tube
Proper laryngoscope exam to visualize glottic opening; remember the axiom: tongue is an enemy, epiglottis is a friend in laryngoscopy exam
7th P = Post -intubation care
"Confirm" tube is in:
C = Clinical exam - 5 points auscultation: Right upper & lower, left upper & lower, & epigastric region
C = Clinical by direct laryngoscopy
C = Chest X-ray
C= Carbon dioxide (End-tidal) detector
C = Condensation of Et tube from direct visualization
Keep warm, maintain BP, drugs infusions, etc
2. Difficult Airway
"The difficult airway is something one anticipates, the failed airway is something one experiences" - Ron Walls
Difficult airway can be due to:
1. Difficult Bag Valve Mask (BVM); mnemonic = MOANS
2. Difficult laryngoscopy and dificult intubation; mnemonics = LEMON
3. Difficult cricothyrotomy; mnemonic = SHORT
4. Difficult extraglottic devices; mnemonic = RODS
In the 2nd edition of Ron M. Wall's Manual of Emergency Airway Management, it was only mentioned of the 3 dimensions of difficult airway, namely the first three mentioned: difficult BVM, difficult laryngoscopy and intubation and difficult cricothyrotomy. This is known as the Sakle's triangle. In the 3rd edition of that book, the 4th dimension, difficult extra-glottic devices is added in.
1. Difficult BVM = MOAN!
M = Mask seal not good, e.g. beard, facial deformity, etc
O = Obesity (difficult ventilate), 3rd trimester pregnancy, or obstruction e.g. neck swelling, angioedema, hematomas, cancer, etc
A = Age, elderly, loss of muscle tone to support the upper airway
N = No teeth (no teach causing caved in face)
S = Stiff lungs - upper airway obstruction - exacerbation of asthma, COPD, etc
2. Difficult laryngoscopy: use LEMON
L = Look externally, e.g. short neck, large tongue, large teeth, etc
E = Evaluate 3-3-2
- 3 = adequacy of oral access
- 3 = to assess capacity of mandibular space to accommodate tongue
- 2 = distance of larynx to level of base of tongue
M = Mallampati scoring
- Difficulty to sit up; use tongue depressor, etc
- difficult to do proper, complete Mallampati
O = Obstruction
Any signs of upper airway obstruction?
three cardinal signs of upper airway obstruciton:
- muffled voice (hot potato voice),
- difficult swallowing secretions,
- stridor; when stridor happens, consider that circumference of airway reduced to roughly 10% of normal caliber!!!!
N = Neck mobility
3. Difficult cricothyrotomy
S = previous surgery
H = Hematoma/swelling around neck
O = Obesity
R = Radiation distortion
T = Tumor
4. Difficult Extraglottic devices
R = Restrictied mouth opening
O = obstruction upper airway
D = Disrupted or distorted upper airway
S = stiff lungs, spine of cervical
3. Acute Deterioration in Intubated Patient:
Four common causes of acute deterioration in any intubated patient are recalled by the mnemonic DOPE
D = tube Displacement
O = tube Obstruction
P = Patient (this is the first priority, not the machines), Pneumothorax, and
E = Equipment failure).
1. Features in CT Scan to screen for:
"Blood Can Be Very Bad"
B = Blood clots - extradural, subdura, intra-parenchyma
C = Cistern - cisterns patent? suprasellar, quadrigeminal. etc
B = Brain parenchyma - Sulci-gyri differentiation, cerebral edema, diffuse axonal injuries features; any lesions? perilesional edema?
V = Ventricles - normal? dilated?
B = Bone. Any fracture?

2. Volume of intracranial bleed of CT
= ABC/2

A is the maximal diameter of the hematoma by CT
B is the diameter 90° to A, and
C is the approximate number of CT slices with hemorrhage multiplied by the slice thickness
Vol > 20 - 30 ml consider surgery

Emergency Medicine
1. Diabetic Ketoacidosis

Triad of DKA is D.K.A.
Diabetics with sugar more than 14 mmol/l
Ketonemia +ve at 1:2 dilution or Ketonuria at least 3+
Acidosis with pH less than 7.3 or HCO3- less than 15 mmol
Note: Remember: 14 and 15
1.2. The signs and symptoms of DKA is D.K.A.
D = Delirium, diuresis, dehydrated (3D)
K = Kussmaul breathing, ketotic breath (2K)
A = Abdominal pain (1A)
1.3. The precipitating factors of DKA is SSSSS..................
S = Sepsis
S = Surgery
S = Stress
S = Sugar high due to skipped insulin
S = Substance abuse, dope, alcohol
1. For the insulin infusion sliding scale, a rough guide to remember would be:
The Insulin Infusion Rate = (RBS Reading) / 5
e.g. RBS = 20, therefore insulin infusion rate = 20/5 = 4u/hour
Monitor RBS hourly.
Ref: Manual of Anaesthesia for Medical Officers by CY Lee

2. Calculated serum osmolality 2 (Na) + Urea + Glucose
Normal = 280 - 300 mmol/l
High osmolar gap is when the actual measured osmolality is greater than 10 mmol/l compared to calculated osmolality
3. Bicarbonate therapy in severe metabolic acidosis
Target bicarbonate level 8 is 10 mmol/l
Target pH is 7.20
Formula for amount of bicarbonate needed:
0.5 * (target bicarbonate level - current bicarbonate level) * body weight
Current bicarbonate level 4 mmol/l
Target bicarbonate level 8 mmol/l
Body weight 70 kg
Bicarbonate needed: (8-4)*70*0.5 = 140 mmol/l
Wait for 30 minutes after completion of bicarbonate therapy before repeating ABG and decide for further bicarbonate

Adrogue, H. J. Madias, N. E. (1998). Management of life-threatening acid-base disorders. First of two parts. N Engl J Med, 338 (1), 26-34.
Why Bicarbonate are not given routinely for all acidosis?
1. The alkaline shift due to bicarbonate results in left shift of the Oxygen-Dissociation Curve, and thereby resulting in oxygen more difficult to be released

2. High bicarbonate load results in the shifting of the equation HCO3-+H+ = H2CO3 = H2O + CO2 to the right, generating a lot of CO2 release. This can cause paradoxical intracellular acidosis. Intracellular acidosis in myocardial cells for example, may result in impaired myocardial contractility

3. High sodium load from sodium bicarbonate results in hypernatremia and hyperosmolarity, particularly harmful in children

2. Concept and Formula In Acid Base Equations:
A. Metabolic Acidosis
Winter's equation:
Expected pCO2 = 1.5 * [HCO3-] + 8 (+/-2)
If the measured PaCO2 is less than the expected → concurrent respiratory alkalosis
If the measured PaCO2 is more than the expected → concurrent respiratory acidosis
Winter’s rule
states that the last 2 digits of pH greater than 7 predicts the PaCO2 in a compensatory respiratory mechanisms
Pt with metabolic acidosis with pH 7.25, the predicted PaCO2 would be 25 mmHg
Delta Gap = Measured AG – normal AG (Normal AG taken as from 3 - 11, average 7)
Delta gap + measured HCO3- MUST BE equal back to the normal HCO3-
If Delta Gap + measured HCO3 more than normal HCO3-, this means there are too much HCO3-, therefore there is co-existing metabolic alkalosis
If Delta Gap + measured HCO3 less than normal HCO3, there is co-existing normal anion gap metabolic acidosis (besides the wide anion gap metabolic acidosis)
The presence of very high AG (more than 20) suggests wide anion gap metabolic acidosis EVEN IN THE PRESENCE OF NORMAL pH!!!
Bicarbonate therapy
Return blood pH to 7.2
plasma bicarbonate 8 to 10 mmol/l
Sodium bicarb needed = (body weight * [target – measured HCO3-] * 0.5) mmol/l
B. Metabolic Alkalosis
Expected PCO2 would be
(0.6 * [HCO3- - 24] + 40) mmHg
If measured PCO2 is less than expected → concurrent respiratory alkalosis
If measured PCO2 is more than expected → concurrent respiratory acidosis
C. Respiratory Acidosis/Alkalosis
In acute setting,
For every 10 mmHg change of PCO2
[HCO3-] changes 1 – 2 mmol/l and
pH changes 0.08
In chronic setting,
For every 10 mmHg change of PCO2
[HCO3-] changes 4 – 5 mmol/l and
pH changes 0.03
D. Partial Pressure of Arterial Oxygen
Predicted PaO2 = FiO2 * 6 (FiO2 in percentage; e.g. FiO2 of 1.0 is 100%; therefore expected PaO2 would be 100*6 = 600)
Predicted PaO2 (in supine position) = [100 – 1/3 * (age in years)]
pH of blood
A rise or fall of pH by 0.10 results in PaO2 falls or rise (opposite direction) by 10%
E. PaO2/FiO2 Ratio
A quick way to estimate impairment of oxygenation
Normal PaO2/FiO2 ratio is 500 – 600 (when FiO2 is expressed in decimal)
Example: in PaO2 80mmHg, FiO2 40%, then PaO2/FiO2 ratio is 80/0.4= 200
PaO2/FiO2 is 300 – indicates ALI
PaO2/FiO2 is 200 – indicates ARDS
F. A-a Gradient
A-a gradient = PAO2 - PaO2
Therefore, A-a gradient = (713*FiO2) - (PaCO2*1.25) - PaO2
Normal A-a gradient = 10 – 20 mmHg
Normal A-a gradient for the particular age = (Age/4 + 4)
High A-a gradient in V/Q mismatch, Rt to Lt shunt, diffusion abnormalities
Adrogue, H. J. and Madias, N. E. (1998). Management of life-threatening acid-base disorders. First of two parts. N Engl J Med, 338(1), 26-34.

Leong, B. and Lee, K. W. (2004) In Guide To The Essentials In Emergency Medicine (Eds, Ooi, S. and Manning, P.) McGraw-Hill, Singapore, pp. 158-68.

Causes of High AG Metabolic Acidosis
Mnemonic #1:

C = Carbon monoxide, Cyanide
A = Alcoholic ketoacidosis
T = Toluene

M = Methanol
U = Uremia
D = Diabetic ketoacidosis

P = Paraldehyde, Phenformin
I = Iron, Isoniazid
L = Lactic acidosis
E = Ethylene glycol
S = Salicylates poisoning

Mnemonic #2:
(because metabolic acidosis like sepsis frequently present with Kussmaul breathing; furthermore, KUSSMAL gives the more commonly causes only that we encounter in our setting)

K = dKA
U = Uremia
S = Salicylates poisoning
S = Sepsis
M = Methanol poisoing
A = Alcoholic ketoacidosis
L = Lactic acidosis

Causes of Normal Anion Gap Metabolic Acidosis
Mnemonic #1 (I prefer to use this mnemonic as USED CARP gives the meaning of the wasting or "used up" bicarbs, thus causing NAGMA):


U = Ureteroenterostomy
S = Small bowel fistula
E = Extra chloride
D = Diarrhea

C = Carbonic anhydrase inhibitors
A = Adrenal insufficiency
R = Renal tubular acidosis
P = Pancreatic fistula

Mnemonic #2:

H = Hyperventilation (chronic)
A = Acetazolamide, Acids (e.g., hydrochloric), Addison's disease
R = Renal tubular acidosis
D = Diarrhea

U = Ureterosigmoidostomy
P = Pancreatic fistulas and drainage
S = Saline (in large amounts) (hyperchloremic metabolic acidosis)

3. The use of CHADS2 score is a scoring system to identify risk factors for developing stroke in patients with nonrheumatic atrial fibrillation.

The acronym of CHADS2 stands for:

C = Congestive Heart Failure
H = Hypertension or treated hypertension
A = Age 75 yrs or older
D = DM
S = Stroke or TIA previously

C-H-A-D each component: 1 point
S (previous stroke or TIA) = 2 points

If patient has 0 point: it is classified under low risk = aspirin daily will do

If patient has 1 point: it is classified under moderate risk: either aspirin, or warfarin with INR target 2 - 3

If patient has 2 or more points: it is classified under high risk: warfarin with INR 2 - 3 is needed

The higher the score, the higher the stroke risk

Patient with mitral stenosis or prosthetic heart valve is classified as high risk, and therefore warfarin is needed.

* The use of warfarin to prevent stroke must be balanced with the risk of developing bleeding due to the use of warfarin.

Gage BF, Waterman AD, ShannonW, et al. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864–70
4. Asthma
Common Medications used to treat ASTHMA:
A = Albuterol
S = Steroid
T = Theophylline
H = Humidified Oxygen
M = Magnesium (MgSO4)
A = Antileukotrienes

5. Causes of ST Elevation in ECG

B = Brugada
C = CNS Pathologies

H = Hypertrophy (LVH)
E = benign Early repolarization
L = LBBB (with AMI - Sgarbossa's criteria)
P = Pericarditis

6. Duke's Criteria for Bacterial Endocarditis (BE)

Major Criteria
B = persistent Blood culture +ve >2 times 12 hr part (each C&S taking should be one hour apart, and we should take at least 3 samples)
E = Endocardial involvement from Echo

Minor criteria
F = Fever >/= 38C
E = Echo findings not fulfilling a major
V = Vascular (vasculitis) - Janeway lesions, mycotic aneurysm, etc
EE = Evidences from microbiological/immunology (2)
R = Risk factors/predisposing factors - drug abuse, valvular diseases (predisposing factors)

Immunological evidences icnlude: Roth's Spot, Osler's nodes, GN, RF, etc.
Microbiological evidence - Blood Culture +ve but not fulfilling a major criteria
Definitive Diagnosis requires
2 Major
3 Minor + 1 Major
5 Minor

7. Interventions for critically ill patients in ED.
The mnemonic stands for:

F = Fluid Resuscitation and balance
A = Analgesia
S = Sedation
T = Thromboembolic prophylaxis

H = Head-of-bed elevation
U = stress Ulcer prophylaxis, and
G = Glucose/glycemic control.

This is modified from the FAST HUG mnemonic for CCU. The only component I modified is "F" - Fluid resuscitation and balance rather than Feeding.

8. Causes of altered mental status
A = alcohol
E = epilepsy, electrolytes
I = infection
O = overdose
U = urea

T = trauma
I = insulin
P = Psychiatric
S = Sepsis, shock

9. San Francisco Syncope Rule
The San Francisco Syncope Rule was developed to identify low-risk syncope, and the original study reported 96% sensitivity for detection of short-term (7-day) serious outcomes, defined as death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage, or any condition causing or likely to cause a return ED visit and hospitalization for a related event

The rule categorizes patients as at high risk for serious outcomes if they have a

C = history of Congestive heart failure,
H = Hematocrit <30%, e =" E
lectrocardiogram abnormality,
S = Shortness of breath, or
S = Systolic blood pressure <90 mm Hg (the criteria can be remembered by the mnemonic, CHESS). Internal validation shows that: the rule was 98% sensitive and 56% specific for predicting these events. Ref: Quinn J et al. Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes. Ann Emerg Med 2006 May; 47:448-54. External validation shows that: Sensitivity of the rule to predict serious outcomes was 74%, specificity was 57%, negative likelihood ratio was 0.5, and positive likelihood ratio was 1.7. Ref: Birnbaum A et al. Failure to validate the San Francisco Syncope Rule in an independent emergency department population. Ann Emerg Med 2008 Aug; 52:151.

10. Principles of management in toxicology (Credlt: Dr. Mohd Hashairi)
R = Reduce absorption
E = Enhance elimination
S = Specific antidote
S = Supportive treatment

Criteria to define SIMPLE Febrile seizure

A Simple Febrile seizure is defined as a seizure in a FEBRILE child aged 6 months to 60 months and without:
S = Seizure of focal type
I = Intracranial infection
M = Multiple times a day
P = Past history of afebrile seizure
L = Last longer than 15 minutes
E = Examination abnormalities

* if there is evidence of the above criteria. then it is a complex febrile seizure 


1. When examining lumps and bumps, remember:
6 Students and 3 Teachers go for CAMPFIRE

Site, Size, Shape, Surface, Skin, Scar
Tenderness, Temperature, Transillumination

Regional lymph nodes

2. Causes of Massive splenomegaly
Massive splenomegaly
= Malaria
= chronic Myeloid leukemia
= Myelofibrosis


1. Structures in retroperitoneal space:
  • S = Suprarenal glands (the adrenal glands)
  • A = Aorta/IVC
  • D = Duodenum (second and third segments [some also include the fourth segment] )
  • P = Pancreas (tail is intraperitoneal)
  • U = Ureters
  • C = Colon (only the ascending and descending parts)
  • K = Kidneys
  • E = Esophagus
  • R = Rectum

1. 5 Causes of raised hemidiaphragm on CXR (Credit: Dr. Ng Kian Seng)

P = Pulled  - “Pulled” Upwards Active due to lung fibrosis pulling up the diaphragm passively or lung diseases causing volume loss for example, atelectasis of lower lobes and pneumonectomy
P = Pushed - Pushed upwards due to hepatomegaly, abscess, ascites, pancreatitis, pregnancy
P = Perforate - “Perforation” due to diaphragmatic rupture with herniation of bowels into thorax
P = Phrenic nerve paralysis
P = Pseudo - "pseudodiaphragm” subpulmonic Effusion
In subpulmonic effusion, the hemidiaphragm is not really raised especially if you look at the "unnatural" configuaration and shape of the diaphragm. The elevated pseudodiaphragm will look more horizontal medially and peak laterally

1 comment:

Anonymous said...

P>A>I>N Period of pain, Area where is the pain, Intensity how bad is the pain 1-5 or 10, Nullify is there anything that decreases the discomfort i.e. POC


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