Hyperlactatemia appears to arise from impaired oxygen utilization more often than decreased O2 delivery but doesn’t cause acidemia unless there is impaired renal function. The novel “alactic base excess” may give us an early way to tell when the kidneys are failing to compensate.
Thunderclap headache (TCH) is a concerning symptom and requires diagnostic evaluation. Initial head CT w/o contrast can help detect SAH with negative LR of 0.01 if performed within 6h of headache onset. However, a head CT w/o contrast can miss other causes of TCH and may require advanced imaging and LP.