title: CO2-based tissue expansion: a study of initial performance in ovine subjects.
abstract: BACKGROUND
  Tissue expanders are an essential reconstructive surgical tool commonly utilized in two-staged breast reconstruction. The current technology is limited primarily to saline expansion, which can be a long process requiring frequent office visits. Eliminating the need for percutaneous injections could potentially improve the psychological and physical discomfort associated with the expansion process as well as save time and resources for both the patient and surgeon.
  
  
  OBJECTIVE
  The authors describe a novel system of gradual, controlled, needle-free expansion. The purpose of the study was to evaluate, prior to clinical use, the in vivo communication between CO(2)-based tissue expanders and their paired handheld dosage controllers and the ability of each expander to reach its intended volume.
  
  
  METHODS
  Twelve expanders-three small (400 cm(3)), three medium (650 cm(3)), four large (850 cm(3)), and two full (1100 cm(3))-were implanted in two mature ovines and were expanded daily with CO(2) using 12 paired handheld dosage controllers. Device performance and expansion progress (cm(3)/d) to size-specified volumes were observed and recorded. An on-site veterinarian monitored the animals for signs of distress during and after inflations. After full expansion of the implants, the animals were euthanized and the implants were surgically removed and examined.
  
  
  RESULTS
  All 12 paired devices performed to specification, achieving successful expansion, and measured volumes of explanted expanders confirmed expansion to the labeled volume. Expansion to full volume was achieved in all units in Ovine 1 within 13 days and in Ovine 2 within 11 days. Total implantation time was 21 days in Ovine 1 and 12 days in Ovine 2. No adverse events were encountered.
  
  
  CONCLUSIONS
  This CO(2)-based tissue expansion system offers a novel and potentially valuable tool for reconstructive surgery. This study demonstrated the in vivo performance of a CO(2)-based tissue expander in an ovine model and merits future clinical research efforts. All tested devices accomplished needle-free expansion with the expanders responding to dosage-controller commands within programmed safety limitations. This system has the potential to expedite expansion through gradual, controlled distention of tissue and to simplify the process for both physician and patient.
authors.affiliation: AirXpanders, Inc., 1047 Elwell Court, Palo Alto, CA 94303 USA.jacobsdr@pacbell.net
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Jacobs
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Jones
authors.forename: Robert M
authors.initials: RM
authors.lastname: Menard
mesh_terms: D000818:Animals; D002245:Carbon Dioxide; D007327:Insufflation / Q000379:methods*; D016462:Mammaplasty / Q000295:instrumentation; D012756:Sheep; D015626:Tissue Expansion / Q000379:methods*; D015625:Tissue Expansion Devices
chemical_list: D002245:Carbon Dioxide