Tunnel shape box

Inspired by the St George’s COVID shield, we designed the tunnel shape box with a bendable thin polycarbonate sheet and the same base from our classic box model. The tunnel shape box has the following advantages:

• Quick assembly with no need of gluing
• Easy to store and ship with maximum space efficiency
• Better aerodynamics with no “dead zones”
• Easy disinfection with no corners
• Good seal by rubber groove
• Good stability by quick connect belts

• Inspiration-St George box
• Our tunnel box

Since the St George’s COVID shield was not designed for tracheal intubation, there were no glove ports on the front panel. In order to keep the advantates of quick assembly, easy to store and ship, easy disinfection which are brought by the single bendable flat plastic sheet, we designed a soft front panel integrated with gloves. The inspiration came from from the “cuddle curtains” and the smeirigid boxes. The soft front panel made from transparent plastic film allows the doctor to have very large maneuver.

• Inspiration-cuddle curtains
• Our soft front panel

How to use this box

1. Use the quick connect belts to tie the base around the bed;
2. Connect the face mask to the ventilation circuit through the adapter on the base;
3. Put the wireless video laryngoscope, stylet, endotracheal tube inside the base;
4. Bend the plastic sheet and insert both edges into the rubber groove in the base;
5. Put gloves around the glove adapters on the flat plastic sheet;
6. Put the soft front panel around the tunnel and base;
7. Put the torso drape around the tunnel.

How to make this box

The tunnel model incorporates the concept of the semi-permanent base attached to the bed - allowing quick and easy removal of the top part of the assembly and giving direct access to the patient. The base was milled with HDPE plate and assembled with PVC sheets and 3D-printed adapters.

The great advantage of this model is that it can be shaped from a flat sheet into a tunnel in no time, directly in the intervention room. The polycarbonate sheet was machined on a CNC router. The flat sheet can be bent on the spot and locked into the base with the same mechanism as the classic box prototype. A rubber groove is present on the outer sides of the sheet so that when it is inserted in the base, the rubber seals the two parts together. Disinfection of this model appears to be the easiest as well as its manufacturing since it is just one flat PVC sheet. Since there are no sharp corners at all, we hope that ventilation efficiency will also be improved for this shape.

The ventilation unit is placed on the top of the curve vis-a-vis the patient’s respiratory exits. A two parts adpater with thread connections was 3D printed with PLA.

Both ends, front and back panel, were closed off with a plastic film. For access to the patient, plastic gloves with long sleeves were melted onto hole cut outs for a perfect seal by an electronic soldering gun. A closed rubber band was added to the edge of the plastic film using the same technique, with an appropriate length providing enough force once tied to the tunnel. Small pins were glued on the edge of the tunnel sheet to avoid the detaching of the plastic film.

• Tunnel_view1
• Tunnel_view2
• Tunnel_view3

Particle capture efficiency simulation

The tunnel model allows better ventilation inside the intubation box. First of all because it presents no corners, sharp edges where viral particles might accumulate and get stuck. And also because dead zones present in the classic box model are elimanated in the tunnel, dimishing the total volume and thus improving the flowrate of the aspiration unit and the evacuation of the particles inside the box. The following mesh shape was used to simulate the airflow in the tunnel model and the ventilation efficency of this model is shown in blue on the graph.

Mesh used to simulate the airflow of particles in the tunnel model and results of the efficiency of this model in terms of its ventilation quality

Doctors’ impressions

The tunnel prototype is not best suited for the intubation of COVID-19 patients. The ergonomics involved in the intubation process don’t have enough room in a tunnel which is lacking the space that procurs the classic box with its higher corners.