In the past, surgery was mostly an indoor procedure. A room’s environment was easier to control and manage than outdoors, where just about anything could enter the surgery area. Even in temporary spaces like field hospitals, bacteria seeping through poorly sealed gaps and improper sterilization limited the effectiveness of surgical procedures.
For instance, the Medical and Surgical History of the War of the Rebellion stated that about 26% of amputations during the Civil War resulted in deaths. Amputations were common at the time due to the destructive effects of Minié ball ammo on bones and tissues. Limitations in medical technology also meant many now-treatable wounds developed into gangrene.
Surgical Tent
Fortunately, that’s hardly the case today. Field hospitals, specifically surgical tents, can be made as sterile as hospital operating rooms (ORs) due to medical advances. Well-trained and equipped medical operation teams manage to keep mortality rates as low as 2%. They have the following technologies to thank for that:
Environmental Control Unit
Traditional surgery rooms are rife with pathogens, mainly Staphylococcus aureus and E. coli bacteria. In a study of three types of surgical procedures done in Germany, S. aureus accounted for over 30% of surgical site infections involving traumatology and orthopedics. Meanwhile, E. coli and Enterococcus spp. are common in abdominal surgery.
With adequate sterilization and room ventilation, surgical teams are able to reduce the risk of surgical site infection (SSI). The same couldn’t be said for field hospitals that, back then, relied on open entryways and windows to facilitate airflow. It doesn’t help that unfavorable weather can contribute to SSI and other post-surgery effects.
All that changed for the better with the debut of a portable environmental control system, also known as an environmental control unit (ECU). Designed and built to military specs, an ECU provides the following benefits to field ORs:
- Operation in Extreme Climate: ECUs can work in climate extremes as low as -60°F and as high as 132°F, ensuring comfort amid such temperatures.
- Constant Run Compressor: The compressor can continue to operate despite the desired temperature already achieved, maintaining it for a long time.
- Ease of Redeployment: If necessary, an ECU can be packed up or moved (when equipped with wheel kits) and set up in a new location with ease.
ECUs essentially throw pathogens out of the surgical tent, where the harsh elements will eradicate them, if not instantly. S. aureus, for example, can only survive in temperatures between 59 and 113°F. A few hours out in the arid deserts of the Middle East or an Arctic winter pose a risk to their survival. That said, interior sterilization is still a must.
Additionally, the conducive working environment ECUs provide lowers the risk of errors. Surgeons can’t afford to sweat, lest risk contaminating the open wound, or shake under the cold, lest risk making a wrong move.
High-Efficiency Particulate Air Filter
Did you know that high-efficiency particulate air (HEPA) filters were invented alongside the atomic bomb? The book Green Health: An A-to-Z Guide states that the bomb’s production generated a lot of airborne radioactive contaminants onsite. Unlike pathogens, radioactive matter is known to last for years even when exposed to the elements.
HEPA filters are designed to trap anything that’s no less than 0.3 micrometers in diameter (depending on the MERV rating). Not only do they trap radioactive contaminants, but also bacteria, fungi, and other airborne particles with a 99.97% efficiency.
Medical facilities, especially ORs, are generally required to have these filters in their ventilation. As explained earlier, pathogens are aplenty inside ORs and must be prevented from spreading across the rest of the premises. A medical HEPA filtration system consists of:
- Fibrous Filters: Usually made out of fiberglass or polypropylene, the filtering fibers are arranged at random to boost their chances of catching pathogens and particles.
- Directional Fan: It blows air to the direction of the HEPA filters, further limiting the spread of pathogens and particles across the ventilation system.
- UV Light Emitters: Ultraviolet (UV) radiation is known to be deadly against bacteria and viruses by altering their genetic structure.
The system also benefits from portability advancements, making clean and surgical tents possible. However, most HEPA filters used in this case are in bag form. Called HEPA bags, they’re wrapped around air exchangers and other fan units to initiate filtration. These bags share the same efficiency as their mat counterparts.
Antimicrobial Tent Fabric
Antimicrobial Tent Fabric
Infection control isn’t only important for ensuring the patient and medical staff’s safety. As a surgical tent will likely be reused for as long as it’s intact, its surfaces must stay sanitary at all times. That includes cleaning any blood spills following a surgery.
Today’s surgical tents are primarily made out of polyvinyl chloride (PVC), polyester, or a combination of both. They’re durable and waterproof enough to allow thorough cleaning. Their lightweight and flexibility allow for rapid deployment.
In recent years, however, premise sterilization has been growing as a focal point for field surgery. COVID forced delays in lifesaving surgeries due to the risk of getting the disease from positive patients. In one study of surgeries in Brazil, it was found that the pandemic had caused over two million surgery backlogs between March and December 2020.
PVC, in particular, has the unfortunate downside of not being antimicrobial in nature. The material wasn’t initially made with medical applications in mind. In fact, another study by Brazilian researchers explains that constant UV exposure can aid in further degradation of the PVC. This, in turn, results in the accumulation of more pathogens, known as biofouling.
All that may change soon as research into antimicrobial PVC is taking off. One trial in 2023 involved a PVC infused with 0.1 to 0.5% (in weight) silver nanoparticles. Despite a reduced tensile strength, this form of antimicrobial PVC was able to inactivate up to 99.99% of the COVID-causing SARS-CoV-2 virus.
Some companies like BioCote® are already employing similar processes with a wide range of antimicrobial additives. Besides silver, other additives include zinc, iodopropynyl butyl carbamate, and quaternary ammonium compounds.
Surgical Enclosure
For surgical teams in the field, the risk of open wound infection during surgery can never be too low. Even when surgical operations are done inside the 21st-century surgical tent, the chances of developing an SSI are still between 1% and 3%. The tent interior is still spacious enough to harbor infectants, especially those coming from the outside.
In 2018, Cambridge-based startup SurgiBox came up with a solution: reduce the surgical space to around and above the wound. And so, the surgical enclosure system was born.
Although yet to undergo trials as of this writing, the enclosure has already received grants from various governments. It’s shown promise in limiting the risk of wound contamination and, more importantly, allowing surgical teams to conduct surgery practically anywhere.
A surgical enclosure consists of two parts.
- Inflatable Bubble: Supported by a popup frame, this disposable bubble isolates the surgical wound or area from the outside environment. Pairs of gloved sockets enable surgical teams to conduct the surgery outside the bubble.
- Portable Air Pump: Powered by a lithium-ion battery, the air pump maintains the ideal pressure inside the bubble. It also houses several mat-type HEPA filters to mitigate the risk of infection inside the bubble.
In 2023, the enclosures were fielded as part of a trial run in Ukraine. As towns and villages in the frontline had all but been reduced to rubble, the 50 units SurgiBox sent would prove indispensable for displaced civilians. The company also markets its enclosures for use in areas devastated by natural disasters.
While not designed to eliminate the risk of SSI, a surgical enclosure system can drastically lower it. The isolated space is, on average, no more than 10 cubic feet—a significant drop from an OR’s thousands of cubic feet.
Between-Case Cleaning
Over the past several wars (not just the two biggest ones), surgical teams struggled with sanitizing the OR between surgeries. Field hospitals tend to fill up with the wounded and worse cases quickly due to ongoing battles within its jurisdiction. The same can be said for the first few days or weeks following a destructive calamity.
Nevertheless, between-case cleaning is crucial in ensuring a clean surgical environment. A bit of prep time, typically 20 to 30 minutes, is of relatively minor consequence compared to the lives saved. Within that timeframe:
- All surfaces should be cleaned and disinfected
- Surgical instruments and other critical equipment must be sterilized
- The floor area within 1.5 meters of the operating table must be cleaned
- Waste bins should be emptied, their waste bagged for final disposal later
Cleaning a surgical tent should be easier, being smaller and housing fewer equipment than hospital ORs. If anything, between-case cleaning is more important in such a setting due to outdoor environmental exposure.
The Centers for Disease Control and Prevention (CDC) urges healthcare professionals to define cleaning frequency based on:
- Probability of contamination
- Patient’s vulnerability to infection
- Potential for exposure to pathogens
Related Reading:
New Hydrogel-Based Spray Combats Infections and Antibiotic Resistance
FAQs: Portable Surgical Tents and Hospital-Grade Sterility
How clean can a surgical tent really get?
With modern tech like HEPA filters, environmental control units, and antimicrobial materials, today’s surgical tents can reach sterility levels comparable to hospital ORs.
What is an environmental control unit (ECU)?
It’s a portable system that controls temperature, humidity, and airflow—crucial for keeping pathogens out of field surgeries, even in extreme climates.
Why are HEPA filters important in a field OR?
They trap over 99% of airborne particles, including bacteria and viruses. In a surgical tent, that’s a critical line of defense against infection.
Is the tent fabric itself antimicrobial?
Not always. Traditional PVC isn’t antimicrobial, but new materials infused with silver nanoparticles or other additives are changing that.
What is a surgical enclosure, and why does it matter?
It’s a portable, bubble-like shield that isolates the surgical area. It reduces infection risk by creating a micro-OR around the wound, even in disaster zones.
How is the tent cleaned between surgeries?
Surfaces, tools, and floors are disinfected thoroughly. Quick, standardized “between-case” cleaning routines help keep the space safe for each new patient.
Can these technologies be used outside of the military?
Yes. They’re already being used in disaster relief zones, conflict areas, and remote communities where regular ORs aren’t available.
Conclusion
Field surgeries today are much safer and more effective than over a century ago, thanks to medical advancements. From powerful ECUs to between-case cleaning, it’s possible for a surgical tent to be as sterile as hospital ORs.
References
Burns, S. (2021). Surgery in the Civil War | Behind the lens: A history in pictures. PBS. https://www.pbs.org/mercy-street/uncover-history/behind-lens/surgery-civil-war/
HARTMANN SCIENCE CENTER. (2023). Bacteria in the operation room. https://www.hartmann-science-center.com/en/hygiene-knowledge/hygiene-measures/surgical-site-infections/bacteria-in-operation-room
Missiakas, D. M., & Schneewind, O. (2013). Growth and laboratory maintenance of Staphylococcus aureus. Current Protocols in Microbiology, Chapter 9(Unit 9C.1). https://doi.org/10.1002/9780471729259.mc09c01s28
Ogunseitan, O. (2025). Green health: An A-to-Z guide. SAGE Publications. Retrieved April 24, 2025, from https://books.google.com.ph/books?id=XtXJzogLCecC&pg=PA13&redir_esc=y#v=onepage&q&f=false
United States Environmental Protection Agency. (2019). What is a HEPA filter? https://www.epa.gov/indoor-air-quality-iaq/what-hepa-filter
Truche, P., Campos, L. N., Marrazzo, E. B., Rangel, A. G., Bernardino, R., Bowder, A. N., Buda, A. M., Faria, I., Pompermaier, L., Rice, H. E., Watters, D., Dantas, F. L. L., Mooney, D. P., Botelho, F., Ferreira, R. V., & Alonso, N. (2021). Association between government policy and delays in emergent and elective surgical care during the COVID-19 pandemic in Brazil: A modeling study. Lancet Regional Health – Americas, 3, 100056. https://doi.org/10.1016/j.lana.2021.100056
da Silva, D. J., Gramcianinov, G. B., Jorge, P. Z., Malaquias, V. B., Mori, A. A., Hirata, M. H., Lopes, S. A. M., Bueno, L. A., Champeau, M., & Carastan, D. J. (2023). PVC containing silver nanoparticles with antimicrobial properties effective against SARS-CoV-2. Frontiers in Chemistry, 11, 1083399. https://doi.org/10.3389/fchem.2023.1083399
Johns Hopkins Medicine. (2019). Surgical site infections. https://www.hopkinsmedicine.org/health/conditions-and-diseases/surgical-site-infections
Newey, S. (2018). UK funded inflatable operating theatre set to revolutionise emergency surgery. The Telegraph. Retrieved April 25, 2025, from https://www.telegraph.co.uk/global-health/climate-and-people/uk-funded-inflatable-operating-theater-fits-rucksack-set-revolutionise/
Teodorescu, D. L., Nagle, D., Jonnalagedda, S., Miller, S., Smalley, R., & King, D. R. (2018). Developing a low-cost, ultraportable, modular device platform to improve access to safe surgery. In Springer eBooks (pp. 97–109). https://www.researchgate.net/publication/325796943_Developing_a_Low-Cost_Ultraportable_Modular_Device_Platform_to_Improve_Access_to_Safe_Surgery
Mathenge, C., & Prasad, Y. G. (2021). Cleaning the operating theatre. Community Eye Health, 34(111), 25–26. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528056/
Centers for Disease Control and Prevention. (2024). Environmental cleaning procedures. Healthcare-Associated Infections (HAIs). U.S. Department of Health and Human Services. https://www.cdc.gov/healthcare-associated-infections/hcp/cleaning-global/procedures.html
