Physiologymiddle twist
A 22-year-old woman is brought to the emergency department 30 minutes after an argument at home, breathing rapidly and deeply. She complains of tingling around her mouth and in both hands. Her wrists are flexed, the fingers are extended at the interphalangeal joints and the thumbs are drawn across the palms. She is afebrile and the tendon reflexes are brisk.
pH 7.53 (7.35-7.45) PaCO2 26 mmHg (35-45) Total calcium 2.34 mmol/L (2.15-2.55) Albumin 41 g/L (35-50) Potassium 3.3 mmol/L (3.5-5.2) Magnesium 0.86 mmol/L (0.70-1.10) Lactate 1.1 mmol/L (0.5-2.0)
Which one of the following changes best accounts for the posture of this woman's hands?