CU News

CU Doctors Unveil Negative Pressure Cabinets for Collecting Specimen from COVID-19 Patients

Doctors from the Faculty of Medicine, Chulalongkorn University have created the “Negative pressure cabinet for collecting specimen” from patients infected with COVID-19. The invention allows medical staff to safely collect respiratory secretions from the throat and nasal cavities and avoid direct contact with patients. The COVID-19 virus is transmittable via droplets, which may spread while talking, sneezing or coughing, within a distance of 1-2 metres. To collect specimen, a sample must be taken from the inner throat or nose area. This may stimulate the patient to sneeze or cough, spreading germs in the air over a wide area and is difficult to control. Unfortunately, the negative pressure room for collecting specimen from patients requires a large investment and cannot be provided in every hospital, so the pressure cabinets will be useful.

As more patients become infected with COVID-19, the jobs of medical staff responsible for screening patients at various hospitals have become more demanding.  Even the large hospitals do not have enough negative pressure rooms.

Dr. Pasurachate Samorn, from the Department of Surgery, Faculty of Medicine, Chulalongkorn University, revealed that during the COVID-19 situation, collecting the specimen from patients by medical staff at the least risk is vital. The Faculty of Medicine has developed the negative pressure cabinet that complies to the standards of specimen storage, effectively prevents the proliferation of germs and can be moved around easily. The cabinet is made from 15 mm thick acrylic sheets, which is resistant to antiseptics, clear and can be seen from the outside. Inside the cabinet is an air cleaner with HEPA filter, the best grade filter, which can capture 99.995% of small particles as virus. The UV-C light disinfection installed makes sure the virus loses its disease-causing ability.  Compared to N95 masks that can filter particles of 0.3 microns, this cabinet is more than a 1 ,000 times more efficient for virus prevention.

The negative pressure cabinet for collecting specimen is now used at the COVID-19 ward at King Chulalongkorn Memorial Hospital and can be moved around, reducing the risk of infection among medical staff.

Dr. Pasurachate said that patients should not worry about the risk of cross-contamination from patient to patient, since the particle filter will clean the air in the cabinet and the cabinet is sterilized by UV-C light.  Besides, after every use, the cabinet will be wiped down and sprayed with alcohol.  To date, eight cabinets, out of the total 50 cabinets, are in use at King Chulalongkorn Memorial Hospital.  10 cabinets will be used at King Chulalongkorn Memorial Hospital, and the rest will be distributed to various hospitals, including Yala Hospital, Pattani Hospital, and Queen Savang Vadhana Memorial Hospital. At the cost of 100,000 baht per unit, each is sponsored by the TCP group.  Also, the idea is open for anyone interested in producing or improving the cabinet for further medical use.”

This cabinet is a collaboration between the Department of Surgery and the Infectious Disease Unit, Department of Internal Medicine, Faculty of Medicine, Chulalongkorn University, by using materials produced and readily available in the country. Once the COVID-19 crisis is resolved, the cabinet can be used in the long term to collect specimen for other respiratory diseases, such as tuberculosis and influenza.  However, we are facing a shortage of medical equipment at the moment. If anyone has the potential to do so, let us all help and pitch in.  Nevertheless, initially consulting with doctors and actual users is the best way to ensure safety”, Dr. Pasurachate concluded.

Dr. Kanit Wongisaret, General Surgery Medical Student, further explained about the items in the negative pressure cabinet. Apart from air cleaners with small particle filter, there are also items, such as disposable gloves, cotton swabs for collecting secretions, glass tubes for collecting specimen and the litter bins. When a patient enters the cabinet, the air cleaner will be switched on. The doctor will examine the secretion from the patients and collect the specimen in a glass tube. The cotton swab will be trashed and the cabinet cleaned.

“The COVID-19 outbreak has left many infected and the number is still on the rise.  There may not be enough internal medicine physicians specializing in specimen collection to meet the needs.  In the end, it is likely that doctors in other fields must join to help with the screening and testing, not just the resident doctor. This invention keeps our medical professionals safe and reduces worry while collecting specimen”, Dr. Kanit concluded.

Chula’s encouragement and support for research is excellent for teachers, students, and the public.

Associate Professor Dr. Suchana Chavanich Faculty of Science, Chulalongkorn University

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