A vital-signs patch for a patient monitoring system that includes a housing containing a sensor that makes physiological measurements of a patient, a transmitter, a receiver, a memory, and a processor. The processor periodically takes a measurement from the sensor, converts the measurement to a data record, and stores the data record in the memory. Upon receipt of a signal from another device, the processor retrieves at least a portion of the data record, converts the retrieved portion of the data record to a vital-sign signal, and causes the transmitter to transmit the vital-sign signal to the other device.