Abstract
Applying cold is a common method for epistaxis management. In this study, the effect of cold on the blood flow of the internal and external carotid system was examined, with the help of ultrasonography, to get a more accurate picture of the effect of cold on blood flow to the head and neck. This study consisted of three separate phases conducted on healthy adult volunteers. Phase 1: Cervical skin and tympanic temperatures, systolic and diastolic blood pressure (SBP and DBP), and heart rate (HR) were measured at baseline and every 5 min for 25 min, with an ice collar in place and after removal. Phase 2: Blood flow of the Internal carotid artery (ICA), External carotid artery (ECA), Facial Artery (FA), and Temporalis Artery (TA) were assessed before applying a regular cervical collar, and promptly after removing it, using Doppler ultrasound. FA and TA blood flows were also measured 5 and 15 min after collar application. Phase 3: The second phase was repeated, this time using an ice collar. Blood flows were additionally assessed 10 min after collar removal. Cold application was associated with tympanic and cervical skin temperatures (P-values: 0.002, < 0.0001), while it had no association with HR, SBP, or DBP (P-values: 0.16, 0.51, 0.36). Applying a regular collar did not affect ICA, ECA, FA, and TA blood flow (P-values:0.9,0.1,0.5,0.06). Pearson's correlation coefficients for flow assessment of ICA, ECA, FA, and TA by Doppler ultrasound before collar use and after its removal were 0.73, 0.96, 0.76, and 0.90, respectively (P-values: 0.01, < 0.001, 0.02, < 0.0001). The cold application did not alter ICA blood flow (P-value: 0.1) but decreased ECA, FA, and TA blood flows (P-values: 0.0002, < 0.0001, < 0.0001). Cold application on the neck can significantly decrease ECA, FA, and TA blood flows, while ICA blood flow remains unchanged. These findings indicate a differing effect of cold on the neck in epistaxis management within the internal carotid system, compared to the external carotid system.