Clinical Lab & ECG Interpretation
Guide
High-Yield Protocols for Rapid Diagnosis
Prepared by: Dr. Mohammed Al-Salahi
I. ECG Mastery: Rapid Interpretation
1. The Systematic Approach (6 Steps)
1. Rate: 300 / large squares between R-R.
2. Rhythm: Is it regular? Are there P waves before every QRS?
3. Axis: Look at Leads I and aVF.
4. P-wave: Look for enlargement or absence.
5. PR Interval: Normal is 0.12 - 0.20s (3-5 small squares).
6. QRS Complex: Narrow (<0.12s) or Wide?
ST-Segment Warning: Elevation in 2+ contiguous leads indicates STEMI.
V2-V4: Anterior | II, III, aVF: Inferior | I, aVL, V5-V6: Lateral.
II. Lab Interpretation: CBC & Electrolytes
1. Anemia Differential based on MCV
Type of
MCV Level Common Causes
Anemia
Low (<80) Microcytic Iron deficiency, Thalassemia, Sideroblastic.
Normal
Normocytic Acute blood loss, Hemolysis, Chronic disease.
(80-100)
© 2026 Dr. Mohammed Al-Salahi | Medical Excellence Series
Guide
High-Yield Protocols for Rapid Diagnosis
Prepared by: Dr. Mohammed Al-Salahi
I. ECG Mastery: Rapid Interpretation
1. The Systematic Approach (6 Steps)
1. Rate: 300 / large squares between R-R.
2. Rhythm: Is it regular? Are there P waves before every QRS?
3. Axis: Look at Leads I and aVF.
4. P-wave: Look for enlargement or absence.
5. PR Interval: Normal is 0.12 - 0.20s (3-5 small squares).
6. QRS Complex: Narrow (<0.12s) or Wide?
ST-Segment Warning: Elevation in 2+ contiguous leads indicates STEMI.
V2-V4: Anterior | II, III, aVF: Inferior | I, aVL, V5-V6: Lateral.
II. Lab Interpretation: CBC & Electrolytes
1. Anemia Differential based on MCV
Type of
MCV Level Common Causes
Anemia
Low (<80) Microcytic Iron deficiency, Thalassemia, Sideroblastic.
Normal
Normocytic Acute blood loss, Hemolysis, Chronic disease.
(80-100)
© 2026 Dr. Mohammed Al-Salahi | Medical Excellence Series
