Measurement of the Force Required by Blunt-Tipped Microcannulas to Perforate the Facial Artery

Purpose: To measure the force required by blunt-tipped microcannulas of various sizes to penetrate the wall of the facial artery. Methods: Twenty hemifaces of 10 fresh frozen cadavers were dissected to reveal the facial artery from its origin at the external carotid artery until the angular artery was found. On the right side of each cadaver, the facial artery was removed at the nasolabial fold, while arteries on the left were kept in situ, preserved with their fascial attachments. A force-sensitive resistor (Tekscan, Boston, MA, U.S.A.) was used to measure the force required by a syringe attached to 18G, 22G, 23G, 25G, and 27G blunt-tipped microcannulas, to pierce the proximal wall of the facial arteries on the left hemiface at the nasolabial fold. The facial arteries from each right hemiface were pierced by cannulas that were attached to a horizontally mounted microtensile load cell, which included a linear motor (Ibex Engineering, Newbury Park, CA). The force required to perforate the proximal wall of the facial arteries was calculated for each cannula. A 2-tailed t test was used to compare the forces measured by the force-sensitive resistor and the microtensile load cell. Results: On force testing, the 18G and 22G cannulas were unable to penetrate the vessel wall in facial arteries that were both: removed from the cadavers and maintained in the cadavers. There was no statistically significant difference between the values obtained by the load motor and the force-sensitive resistor (p = 0.33). The force required to penetrate the proximal wall of the facial artery was: 0.72 kg to 0.81 kg for 23G, 0.43 kg to 0.54 kg for 25G, and 0.23 kg to 0.32 kg for 27G blunt-tipped microcannulas. There was a significant correlation between the gauge of the cannulas and the force required to penetrate the vessel walls (r = −0.970; p =

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