ECG
Urine pregnancy (if age/sex appropriate)

CBC (or POC hemoglobin) & chemistry (or POC glucose)
TSH
Tox screen (urine or serum – based on clinical scenario)
Bedside cardiac echocardiography
Cardiac hypertrophy or pericardial effusion
Assess the IVC for dehydration
Cardiac hypertrophy or pericardial effusion
Assess the IVC for dehydration
ECG may show:
WPW – short PR, Delta waves, wide QRS
Long QT syndrome – QTc >0.450 sec
Hypertrophic cardiomyopathy – LVH, ST changes, T wave inversions, lateral leads needle like Q waves and absent R waves
Brugada syndrome – incomplete RBBB with ST elevations in V1-3
Arrhythmogenic right ventricular dysplasia (ARVD) – incomplete RBBB with T waves inversion in V1-3, epsilon wave is pathognomonic (up-notching of a terminal Q wave)
Catecholaminergic polymorphic ventricular tachycardia - May present with VT/VF due to emotional stress or a regular ECG
WPW – short PR, Delta waves, wide QRS
Long QT syndrome – QTc >0.450 sec
Hypertrophic cardiomyopathy – LVH, ST changes, T wave inversions, lateral leads needle like Q waves and absent R waves
Brugada syndrome – incomplete RBBB with ST elevations in V1-3
Arrhythmogenic right ventricular dysplasia (ARVD) – incomplete RBBB with T waves inversion in V1-3, epsilon wave is pathognomonic (up-notching of a terminal Q wave)
Catecholaminergic polymorphic ventricular tachycardia - May present with VT/VF due to emotional stress or a regular ECG
Syncope 
Seizure
Laryngospasm
Breath-holding spell
Chest pain 
Hyperventilation syndrome
Sedation 
Pregnancy 