A patient monitoring system has one or more ultrasound devices that monitor patients. The ultrasound devices can communicate to a central station by way of a wireless data communication network. Ultrasound images acquired by the ultrasound devices may be displayed at the central station. Alarms may be generated based upon conditions detected by the ultrasound devices. An ultrasound device may have a strap that permits it to be held in place with a transducer against the skin of a subject to permit ultrasound observation of the subject either continuously or intermittently over an extended period.