title: Measurement of trocar insertion force using a piezoelectric transducer.
abstract: We attempted to establish a model to measure the force required for trocar insertion at laparoscopy. A 3-cm, circular transducer was constructed from piezoresistive material that changes its impedance as force is exerted on its surface. The transducer is connected by an interface box to a personal computer to record surface contact pressure digitally (pressure = force/area) profile continuously during trocar insertion. Each subject had three trocars inserted: a 10-mm trocar at the umbilicus after creation of pneumoperitoneum, and 5-mm trocars at corresponding sites on the left and right sides of the lower abdomen. All insertions were performed by the same operator using reusable trocar with a conical tip. Each subject acted as her own control. Recordings were successfully obtained from eight women. There was no instance of transducer failure. The mean (SE) peak contact surface pressure for the 10-mm and 5-mm left and right trocars were 5.3 (0.32), 6.4 (0.51), and 6.81 (0.27) pounds/square inch, respectively. Placement of the 10-mm trocar required less insertion force than placement of the 5-mm trocars. There was a strong negative correlation (r = -0.97, p < 0.001) between body weight and peak insertion force for the 10-mm trocar.
authors.affiliation: Department of Obstetrics and Gynaecology, Chinese University of Hong Kong, Prince of Wales Hospital, Sha Tin, NT, Hong Kong SAR, China.
authors.forename: Pui Shan
authors.initials: PS
authors.lastname: Ng
authors.forename: Daljit Singh
authors.initials: DS
authors.lastname: Sahota
authors.forename: Pong Mo
authors.initials: PM
authors.lastname: Yuen
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004560:Electricity; D005260:Female; D006801:Humans; D010535:Laparoscopy / Q000379:methods*; D008875:Middle Aged; D008954:Models, Biological; D013525:Surgical Instruments; D014159:Transducers