A 22 year old man is brought in by paramedics, after being found unconscious in a park. No history is available. His complete blood count, random capillary glucose, serum electrolytes, and renal and liver functions are all found to be normal.
The CT scan of the brain is normal, with no evidence of hemorrhages, space occupying lesions, midline shift, or edema.
The rate is 120 bpm, with occasional premature ventricular complexes. The P waves, QRS complexes and T waves are of normal morphology, with a QRS duration of 80 ms. The PR and QT segments are isoelectric and of normal duration. There is mild right-axis deviation.
On room air: PaO2: 90 mmHg (75-95) PCO2: 40 mmHg (35-45) SaO2 : 99% PH: 7.40 (7.35-7.45) HCO3: 24 mmol/L (24-32)
Amphetamines, Acetaminophen, Benzodiazepines, Opiates, Cannabinoids, Methadone, Ethanol: not detected Tricyclic Antidepressants: positive