According to various embodiments, a medical device may include a hat and an annular securing device coupled to the hat and configured to adjustably secure the hat to a patient's body. The annular securing device may be configured to reduce in circumference when at least one end of the annular securing device is pulled in an axial direction. The medical device may also include a sensor disposed on the hat or annular securing device. The sensor may be configured to communicatively couple to the patient's body.