If you and your team just can't get an arterial line into your critically ill, hypotensive patient for continuous invasive blood pressure measurement, you may be somewhat comforted by a study in Critical Care Medicine. Authors found that among 150 critically ill patients (83 of whom were in shock), mean arterial pressure (MAP) measurements with an arm cuff were highly reliable at detecting clinically relevant hypotension, as compared to invasive BP monitoring with an arterial line. Measurements of MAP at the ankle and thigh were inferior but also accurate for this purpose, depending on one's standard for certainty. However, blood pressure cuff measurements were less precise, frequently varying widely from the results on invasive monitoring.