Negative Pressure Aerosol Chamber
Smoke evacuator suction tubing (Stryker Corporation; Product# 0700-026-000; Kalamazoo, MI) was placed under the drape and connected to a Neptune 3 Waste Management System (Stryker Corporation; Kalamazoo, MI) to create a negative pressure chamber for the aerosol housing system. The Neptune 3 Waste Management System is a surgical suction system designed to provide both hazardous fluid and smoke evacuation during surgery. It contains both a smoke evacuator filter compartment with an ultra-low penetrating air (ULPA) efficiency rating and a fluid suction high-efficiency particulate air (HEPA) filter compartment. The tubing is connected to the smoke evacuator manifold port on the Neptune suction system to provide a minimum negative pressure of 0.5 inches of water gauge. These metrics are consistent with the minimum ventilation requirements for Class III biological safety cabinets in California. In addition to the suspension apparatus, we created one or more ventilation ports, located near head of the bed, to allow airflow into the negative-pressure chamber. We were not able to measure the pressure under the drape but did verify the suction was active, and when these openings for air intake were occluded the drape tended to collapse.
In the first case and NOVID design, a polyethylene film drape (3M Steri Drape 1010) was supported only by a straight Bookwalter bar. Unfortunately, the single bar did not provide enough structural support, and the drape collapsed and occlude the smoke evacuator under vacuum limiting aerosol clearance. In the final iteration of the negative pressure housing system, we used the Lone Star ring retractor attached to a laparoscopic Bookwalter retractor holder to suspend the drape above the patient’s face without collapse when the negative pressure environment was created. Gauze was also placed near the tip of the smoke evacuator to prevent the drape from occluding the smoke evacuator tip during the surgery.