OSCE Data interpretation stations Dr Cathy Armstrong Consultant Anaesthetist Dec 2014

Objectives The stations – Format – Tips Blood tests – Patterns to look for examples

Format Instructions – Brief background – Study data – ‘after 5 minutes the examiner will ask you some questions on diagnosis & initial management’

Format Data – Blood tests – ECG – CXR – Observations

Format Questions from examiner – Structured / standardised ‘what do the blood tests show?’ ‘what does the CXR show?’ What is your most likely diagnosis? What is your top differential? What will your initial management be?

Tips Use your thinking time wisely Use succinct language & be confident – Likely to be some normal investigations also Show reasoning behind your thoughts Flag up potential dangers

Tips Differential diagnosis – Start with your top & why Initial management – Might include oxygen / fluids / nebulisers – Remember management packages – e.g septic 6 – Further detailed history – Other definitive investigations – e.g.echo, CT – Don’t forget SENIOR HELP / INPUT

Investigations

Full Blood Count Hb – Males 135 – 180g/l – Females 115 – 160 g/l WCC – 4.0 – 11 x 10 9 /l Platelets – 150 – 400 x 10 9 /l

Anaemia classification by MCV MCV – mean cell volume (76 – 96 fl) Normal MCV (Normocytic) – Acute blood loss – Anaemia of chronic disease Low MCV (microcytic) – Iron deficiency – Thalassaemia High MCV (Macrocytic) – B12 or folate deficiency

High wcc - neutrophilia Raised WCC most commonly due to neutrophilia Neutrophils account for 40 – 75% of WBC recognise & ingest foreign particles & microorganisms Causes of neutrophilia – Infection – Trauma – Infarction – Inflammation – Malignancy – Myeloproliferative disease – Physiological (exercise & pregnancy)

Low wcc - neutropenia  Most commonly caused by neutropenia  Causes of neutropenia  Infection  Drugs  Autoimmune  Alcohol  congenital

Thrombocytosis Reactive – Chronic inflammatory disorders – Malignant disease – Post-haemorrhage – Post-splenectomy – Haemolytic anaemias Malignant – Essential thrombocythaemia – Polycythaemia rubra vera – myelofibrosis

Thrombocytopenia Marrow disorders – Hypoplasia – idiopathic, drug-induced – Infiltration Leukaemia, Myeloma, Carcinoma, Myelofibrosis – B12 / folated deficiency Increased consumption of platelets – DIC, ITP, viral infections, bacterial infections Hypersplenism – Lymphoma, liver disease

Urea & electrolytes Na mmol/l K 3.5 – 5.5 mmol/l Ur 2.5 – 6.7 mmol/l Cr 70 – 150 mmol/l

Hyperkalaemia Mild mmol/l Mod6.1 – 7.0 mmol/l Severe > 7.0 mmol/l Causes – ↑ intake Food ingestion / supplements Rapid blood transfusion – Intercompartmental shifts Trauma / crush injuries Burns Acidosis – Decreased excretion Acute / chronic renal failure Adrenocortical insufficiency (e.g. Addisons disease) – Medications Potassium sparing diuretics, digoxin

Hyperkalaemia  ECG changes  Peaked T waves  Prolonged PR interval  Widened QRS  Loss of P wave  Loss of R wave amplitude  Sine wave pattern  Asystole  Management of mod / severe  Treat underlying cause  Calcium gluconate  Insulin dextrose infusion  Nebulised salbutamol  dialysis

Hypokalaemia Mild 3.0 – 3.5 mmol/l Mod2.5 – 3.0 mmol/l Severe < 2.5 mmol/l Causes – ↓ intake Iatrogenic (no K in IV fluids) Malnutrition – Renal losses Renal tubular acidosis Hyperaldosteronism (Conn’s syndrome) – GI losses Diarrhoea, vomiting – Intercompartmental shifts insulin Alkalosis – Medications Diuretics, β2 agonists

Hypernatraemia Usually due to water loss in excess of sodium loss Causes include: – Iatrogenic (too much IV N saline) – Diabetes Insipidus – Primary aldosteronism (Conn’s Syndrome)

Diseases with electrolyte patterns Addisons disease (Primary adrenocortical insufficiency) – NaKCa Cushings syndrome (excess plasma cortisol) – NaKCa Conn’s Syndrome (hyperaldosteronism) – NaK

Diseases with electrolyte patterns Addisons disease (Primary adrenocortical insufficiency) – Na ↓K ↑Ca ↑ Cushings syndrome (excess plasma cortisol) – Na ↑ K ↓ Ca ↓ Conn’s Syndrome (hyperaldosteronism) – Na ↑ ↔K ↓

Raised Urea & creatinine Both raised in renal failure Alternative causes of a raised urea with relatively normal Cr – Dehydration – GI haemhorrhage – High protein diet

Deciphering between acute & chronic renal failure using blood results  Chronic renal failure  Anaemia of chronic disease  Low calcium  High phosphate

Liver Function tests Non-specific Bilirubin AST (Aspartate transaminase) ALP (Alkaline phophatase) γ – GT (Gamma –glutamyl transpeptidase) Albumin Specific ALT (Alanine aminotransferase)

LFT patterns Hepatocellular Damage – Large ↑ in ALT with small ↑ in ALP Biliary obstruction – Small ↑ ALT with large ↑ in ALP & γ -GT

Areas not covered Clotting studies – Anticoagulant monitoring CRP Blood cultures Specialist tests – E.g – vasculitis screens / immunology

Normal ABG Values pH PaO 2 PaCO 2 HCO 3 Base Excess kPa kPa 22 – 26 mmol/l mmol/l Many modern gas machines also measure K + Na + Cl - SaO 2 Hb COHb MetHb Lactate IN AIR

Expected PO 2 on oxygen % oxygen – 10

Examples

Ryan Ryan is a 17 year old male. He has presented to A&E with a 2 month history of general malaise. Over the past few days he has been vomiting with stomach cramps. BP 110/70, Apyrexial, RR 39 Review the investigations provided. You will then be asked questions on diagnosis and initial management.

Ryan

Ryan Hb 12.9 (9.0 – 13.0) Wcc 7.0 (4.0 – 11.0) Plt 395 ( ) Na 139 ( ) K 4.5 ( ) Ur 15.0 ( ) Cr 140 (80-120) Blood glucose 35mmol/l ABG on air pH 7.12 ( ) PCo2 3.0 ( ) PO (10-12 in air) HCO3 17 (22-26) BE -23 (-2- +2)

Ryan

Jack Jack is a 77 year old male. He has presented to A&E with a 2 day history of abdominal pain and vomiting. BP 90/45, T RR 30 Examination of the abdomen reveals a hard abdomen with generalised tenderness and guarding Review the investigations provided. You will then be asked questions on diagnosis and initial management.

Jack Hb 9.0 (9.0 – 13.0) Wcc 22.3 (4.0 – 11.0) Plt 170 ( ) Na 139 ( ) K 4.5 ( ) Ur 10.0 ( ) Cr 130 (80-120) ABG on air pH 7.22 ( ) PCo2 6.1 ( ) PO2 7.5 (10-12 in air) HCO3 18 (22-26) BE -10 (-2- +2)

Jack

Jack

Dorothy Dorothy is a 82 year old female. She has presented to A&E with a 5 day history of productive cough with green sputum and worsening shortness of breath. BP 93/50, T RR 32 Review the investigations provided. You will then be asked questions on diagnosis and initial management.

Dorothy Hb 11.0 (9.0 – 13.0) Wcc 21.0 (4.0 – 11.0) Plt 250 ( ) Na 139 ( ) K 4.5 ( ) Ur 8.0 ( ) Cr 90 (80-120) ABG on 60% oxygen pH 7.35 ( ) PCo2 4.2 ( ) PO2 13 (10-12 in air) HCO3 23 (22-26) BE -3 (-2- +2)

Dorothy

Dorothy

CURB 65 Confusion Urea – 7.0 or over RR 30 or over BP – Systolic 90 or less OR – Diastolic 60 or less Age 65 or over

Sepsis 6 Oxygen Blood cultures IV antibiotics Lactate & FBC IV fluids Measure UO

Tom Tom is a 22 year old male. He has presented to A&E with shortness of breath and an audible wheeze BP 135/90, T RR 38 Review the investigations provided. You will then be asked questions on diagnosis and initial management.

Tom Hb 11.0 (9.0 – 13.0) Wcc 6.0 (4.0 – 11.0) Plt 250 ( ) Na 139 ( ) K 4.5 ( ) Ur 5.9 ( ) Cr 80 (80-120) ABG on 15L oxygen via non-rebreath mask pH 7.32 ( ) PCo2 5.9 ( ) PO2 9 (10-12 in air) HCO3 23 (22-26) BE -3 (-2- +2)

Tom

Tom

summary  Read instructions carefully  Take time to look at data, formulate a differential diagnosis & initial management plan  Be confident in your approach  Remember senior input