Lecture Notes: All Things Rotem and TEG (2022 Exam Preparation)

Overview

Discussed a question from 2022 exam (Part I, Question 4): drawing and labeling a viscoelastic clotting function graph and its modifications due to hyperfibrinolysis.
Emphasis on simplifying and structuring knowledge on TEG (Thromboelastography) and ROTEM (Rotational Thromboelastometry).

Low Pass Rate Analysis: Historical exam questions (25% pass rate) often get repeated, especially if deemed fair.
Example Question Elements:
- Graphing and labeling viscoelastic test results (TEG or ROTEM).
- Linking graph components to coagulation physiology.
- Understanding effects of hyperfibrinolysis.
Common Errors:
- Incorrect labeling and graph axes.
- Confusing terminologies and concepts like hyperfibrinolysis vs. hypofibrinogenemia.
- Lacking physiological linkage in explanations.

mnemonics for graph shapes: Brandy tumbler (normal), sausage (hypocoagulable), leaf (hyperfibrinolysis), etc.
Four Key Phases of Coagulation:
1. Start: Initiation time (R/CT time) linked to coagulation factors (e.g., FFP or prothrombin complex for treatment).
2. Speed: Time from clot start to formation speed (K time/CFT time), influenced by fibrinogen and platelets.
3. Strength: Maximum clot firmness (MA/MCF), reliant on platelet function and fibrinogen.
4. Stability: Clot's stability over time (lysis indices - LY/CL), managed by antifibrinolytics (e.g., TXA).

Normal ROTEM/TEG: Brandy tumbler shape with clearly defined phases.
Hyperfibrinolysis: Severe drop-off in graph, managed with antifibrinolytics.
Hypercoagulable State: Broad and high amplitude indicative of excessive clotting potential.
DIC (Disseminated Intravascular Coagulation): Initial hypercoagulable followed by hypocoagulable state.
Anticoagulant Medication Effect: Prolonged start time, impairing coagulation factor functionality.

Differences in methodology: ROTEM rotates the pin; TEG rotates the cup.
ROTEM Extensions: Focuses on more specific tests (EXTEM, INTEM, APTEM, FIBTEM, HEPTEM) aiding differentiation in component causes.

TEG Normal Values: E.g., R time 5-10 mins, Alpha angle 45-74°, MA 50-70 mm.
ROTEM Normal Values: E.g., EXTEM CT <80 secs, A5 >35 mm, Maximum lysis <5%.
Importance of Context: Know values specific to your institution and always refer to hospital algorithms.

Mnemonic: 4S’s – Start, Speed, Strength, Stability.
Helps structuring the answer and linking pathophysiological changes to graph deviations.

Focus on Simplification: Aim to simplify complex concepts for better retention and application in exams.
Graph Practice: Regularly practice drawing and interpreting TEG/ROTEM graphs to internalize the key concepts and typical visual patterns.
Real-World Application: Understand the clinical scenarios where different viscoelastic profiles are relevant, e.g., obstetrics, trauma.

Mastering TEG and ROTEM involves understanding their theoretical aspects, practicing graph representations, and correlating clinical conditions with viscoelastic changes. Adopting mnemonics and simplified frameworks can significantly aid in passing the exam and practical applications.