CAROTID COMPRESSION DEVICE FOR THE PREVENTION OF RADIATION HAZARD.

Abstract

For the comprehensive investigation of cerebrovascular diseases with the aid of angiography it has become increasingly necessary to demonstrate cerebral vessels in their entirety. This is achieved by a puncture of the internal or common carotid artery. Before and during the injection of the contrast medium the contralateral common carotid is usually compressed in the cervical region with the palpating hand. Diminished vascular pressure of the cerebral vessels is thereby produced at the compressed side and thus the injected contrast substance may fill the opposite arterial branches via the anterior communicating artery. In this particular procedure the examiner's hand performing the compression is exposed to the primary x-ray beam (Fig. 1). If in one examination an average of 6 exposures are made for the anteroposterior and half-axial view, and many times more in a seriogram, it is evident that in several examinations per day the radiation dose to the hand will accumulate considerably. Because of this a device has been developed which prevents primary radiation to the hand while compressing the carotid artery. Description and Operation of Device The existing compression device is based on the principle of sphygmomanometry. A rubber diaphragm (D1) is brought into contact with the patient, and a second diaphragm (D2) with a larger area provides sufficient displacement of air to utilize the full range of a manometer of the aneroid type (Fig. 3). The rubber membrane of the first diaphragm serves to pick up the pulsations of the carotid artery. The pulse is then transmitted to the second diaphragm whose pressure will be registered on the aneroid dial by a slight flicker of the indicator. With complete obliteration of the artery the flicker movement will cease, thereby indicating the systolic pressure. The instrument, attached to a removable metallic rod (Fig. 4), may be manually applied to the neck, with the hand holding the rod of the instrument behind the drawn lead curtain which is in front of the x-ray tube. The examiner's hand is thus removed from the primary x-ray beam (Fig. 2). Application of the Instrument The obliteration of the carotid artery occurs at the first diaphragm which has a steel ring frame 2 cm. in diameter. Pulsations are recorded on the dial by applying the instrument at random in the neck region. When the greatest amplitude is found on the dial the investigator knows that the diaphragm is directly positioned over the desired artery. The search for the best location of arterial compression may be facilitated by digital palpation; when the area of maximal pulsation is found, the palpating finger is then replaced by the instrument. With the diaphragm over the artery and increased manual pressure applied to the instrument the ring around the diaphragm will occlude the artery. It is important to ascertain that the artery is well fixed.