Hypoxemia

While rounding with our newest pediatric pulmonologist:

The seven causes of hypoxemia
1. Low inspiratory partial pressure (fraction) of oxygen: high altitude
2. Alveolar hypoventilation: apnea
3. Impairment of diffusion across blood-gas membrane: pneumonia, interstitial disease
4. Ventilation-perfusion mismatch: asthma
5. Shunt: Arterio-venous malformation, mixing cardiac lesion
6. Reduced mixed venous oxygen content in the context of a shunt: not sure
7. Hemoglobinopathy: carbon monoxide poisoning

Abbreviations: FiO2, a's and b's, a-A gradient, dz, V-Q mismatch, AVM, CO, ddx

Calcium Metabolism: Hypocalcemia

Recognize the signs and symptoms of hypocalcemia


Add this to your differential, guys: hypocalcemia generally makes you more prone to tetany, which is the term for muscle contractions due to neuromuscular excitability. Usually we think of tetany as sustained contractions in the hands, feet, or face, but hypocalcemia can also present as cyanosis or stridor from laryngospasm. So think about it the next time you see croup!

Abbreviations: ical, ca, ddx
Mnemonic: Low cash (Calcium) makes your face twitch (tetany)