Personal Protective Equipment and COVID-19: A Review for Surgeons

: There is a long history of personal protective equipment (PPE) used by the surgeon to minimize the transmission of various pathogens. In the context of the present coronavirus disease 2019 pandemic there is significant controversy as to what forms of PPE are appropriate or adequate. This review aims to describe the pathogenic mechanism and route of spread of the causative virus, severe acute respiratory syndrome coronavirus, as it pertains to accumulated published data from experienced centers globally. The various forms of PPE that are both available and appropriate are addressed. There are options in the form of eyewear, gloves, masks, respirators, and gowns. The logical and practical utilization of these should be data driven and evolve based on both experience and data. Last, situations specific to surgical populations are addressed. We aim to provide granular collective data that has thus far been published and that can be used as a reference for optimal PPE choices in the perioperative setting for surgical teams.

Surgeon Personal Protection: An Underappreciated Benefit of Positive-pressure Exhaust Suits

BACKGROUND

Positive-pressure exhaust suits cost more than standard surgical gowns, and recent evidence suggests that they do not decrease infection risk. As a result, some hospitals and surgeons have abandoned positive-pressure exhaust suits in favor of less expensive alternatives. We propose that in addition to their original purpose of decreasing infection rates, positive-pressure exhaust suits may also improve personal protection for the surgeon and assistants, perhaps justifying their added costs.

QUESTIONS/PURPOSES

(1) Do positive-pressure exhaust suits decrease exposure to particulate matter during TKA? (2) What areas covered by gowning systems are at risk of exposure to particulate matter?

METHODS

Three surgical gowning systems were tested: (1) surgical gown, face mask, surgical skull cap, protective eyewear; (2) surgical gown, face mask, surgical protective hood, protective eyewear; and (3) positive-pressure exhaust suit. For each procedure, a cadaver knee was injected intraarticularly and intraosseously with a 5-µm fluorescent powder mixed with water (1 g/10 mL). After gowning in the standard sterile fashion, the primary surgeon and two assistants performed two TKAs with each gowning system for a total of six TKAs. After each procedure, three independent observers graded skin exposure of each surgical participant under ultraviolet light using a standardized scale from 0 (no exposure) to 4 (gross exposure). Statistical analysis was performed using Friedman's and Nemenyi tests. The interrater reliability for the independent observers was also calculated.

RESULTS

The positive-pressure exhaust suits had less surgeon and assistant exposure compared with other systems (p < 0.001). The median overall exposure grade for each gowning system was 4 for System 1 (range, 3-4), 2.5 for System 2 (range, 2-3), and 0 for System 3 (range, 0-0). In pairwise comparisons between gowning systems, the positive-pressure exhaust suits had less exposure than gowning System 1 (difference of medians: 4, p < 0.001) and gowning System 2 (difference of medians: 2.5, p = 0.038). There was no difference found in exposure between Systems 1 and 2 (difference of medians: 1.5, p = 0.330). When gowning Systems 1 and 2 were removed, particulate matter was found in places that were covered such as the surgeon's beard, lips, inside the nostrils, behind the protective eyewear around the surgeon's eye, and in both eyebrows and eyelashes.

CONCLUSIONS

The positive-pressure exhaust suits provided greater personal protection with each procedure than the other two gowning systems.

CLINICAL RELEVANCE

With conventional gowns, particulate matter was found in the surgeon's eyelashes, under the face mask around the mouth, and inside the nostrils. Despite recent evidence that certain types of positive-pressure exhaust suits may not decrease infection, there is a clear benefit of surgeon protection from potentially infectious and harmful patient substances. Despite their added costs, hospitals and surgeons should weigh this protective benefit when considering the use of positive-pressure exhaust suits.

Surgical Space Suits Increase Particle and Microbiological Emission Rates in a Simulated Surgical Environment

BACKGROUND

The role of space suits in the prevention of orthopedic prosthetic joint infection remains unclear. Recent evidence suggests that space suits may in fact contribute to increased infection rates, with bioaerosol emissions from space suits identified as a potential cause. This study aimed to compare the particle and microbiological emission rates (PER and MER) of space suits and standard surgical clothing.

METHODS

A comparison of emission rates between space suits and standard surgical clothing was performed in a simulated surgical environment during 5 separate experiments. Particle counts were analyzed with 2 separate particle counters capable of detecting particles between 0.1 and 20 μm. An Andersen impactor was used to sample bacteria, with culture counts performed at 24 and 48 hours.

RESULTS

Four experiments consistently showed statistically significant increases in both PER and MER when space suits are used compared with standard surgical clothing. One experiment showed inconsistent results, with a trend toward increases in both PER and MER when space suits are used compared with standard surgical clothing.

CONCLUSION

Space suits cause increased PER and MER compared with standard surgical clothing. This finding provides mechanistic evidence to support the increased prosthetic joint infection rates observed in clinical studies.

Comparison of air exhausts for surgical body suits (space suits) and the potential for periprosthetic joint infection

BACKGROUND

Periprosthetic joint infection is a major complication of total joint replacement surgery and is associated with significant morbidity, mortality and financial burden. Surgical body suits (space suits), originally designed to reduce the incidence of infection, have paradoxically been implicated in increased periprosthetic joint infection rates recently. Air exhausted from space suits may contribute to this increased rate of periprosthetic joint infection.

AIM

To investigate the flow of air exhausted from space suits commonly used in modern operating theatres.

METHODS

The exhaust airflow patterns of four commercially available space suit systems were compared using a fog machine and serial still photographs.

FINDINGS

The space suit systems tested all air exhausted into the operating room. The single fan systems with a standard surgical gown exhausted air laterally from the posterior gown fold at approximately the level of the surgical field. The single fan system with a dedicated zippered suit exhausted air at a level below the surgical field. The dual fan system exhausted air out of the top of the helmet at a level above the surgical field.

CONCLUSIONS

Space suit systems currently in use in joint replacement surgery differ significantly from traditional body exhaust systems; rather than removing contaminated air from the operating environment, modern systems exhaust this air into the operating room, in some cases potentially towards the sterile instrument tray and the surgical field.

Impact of Operating Room Environment on Postoperative Central Nervous System Infection in a Resource-Limited Neurosurgical Center in South Asia

BACKGROUND

Postoperative central nervous system infections (PCNSIs) are serious complications following neurosurgical intervention. We previously investigated the incidence and causative pathogens of PCNSIs at a resource-limited, neurosurgical center in south Asia. This follow-up study was conducted to analyze differences in PCNSIs at the same institution following only one apparent change: the operating room air filtration system.

METHODS

This was a retrospective study of all neurosurgical cases performed between December 1, 2013, and March 31, 2016 at our center. Providers, patient demographic data, case types, perioperative care, rate of PCNSI, and rates of other complications were reviewed. These results were then compared with the findings of our previous study of neurosurgical cases between June 1, 2012, and June 30, 2013.

RESULTS

All 623 neurosurgical operative cases over the study period were reviewed. Four patients (0.6%) had a PCNSI, and no patients had a positive cerebrospinal fluid (CSF) culture. In the previous study, among 363 cases, 71 patients (19.6%) had a PCNSI and 7 (1.9%) had a positive CSF culture (all Gram-negative organisms). The differences in both parameters are statistically significant (P < 0.001). Between the 2 studies, there was no change in treatment providers, case types, case durations, antibiotic administration practices, and patient demographics.

CONCLUSIONS

The rates of PCNSI and positive CSF culture were significantly lower in our present cohort compared with the cohort in our previous study. The sole apparent change involves the air filtration system inside the neurosurgical operating rooms; this environmental change occurred during the 5 months between the 2 studies. This study demonstrates the impact of environmental factors in reducing infections.

Infection Control Practices to Reduce Airborne Bacteria During Total Knee Replacement: A Hospital Survey in Four States

Objective:

To describe the use of laminar airflow, body exhaust, and ultraviolet lights during total knee replacement (TKR) in four U.S. states.

Design:

Survey of healthcare facilities.

Setting:

Hospitals in Illinois, North Carolina, Ohio, and Tennessee that performed TKR during 2000 as identified by Medicare claims data.

Participants:

Hospitals responding to a mailed questionnaire.

Results:

Two hundred ninety-five (73%) of 405 eligible hospitals that performed 18,374 primary and revision TKR procedures responded to the questionnaire. Among responding hospitals, 30% reported regular use (for > 75% of procedures) of laminar airflow, 42% reported regular use of body exhaust, and 5% reported regular use of ultraviolet lights. Among hospitals providing complete data, 150 (58%) performing 66% of procedures reported regular use of at least one of these techniques. On regression analyses, laminar airflow was used more often by hospitals with a TKR volume greater than 25 procedures per year (odds ratio [OR], 2.0; 95% confidence interval [CI95], 1.1-3.7) and orthopedic residency programs (OR,2.8;CI95,1.3-6.3), but its use was not significantly related to hospital setting or ownership status.

Conclusions:

Although these clean air practices are not recommended by any U.S. governmental or professional organization, they are used in nearly two-thirds of TKR procedures. Better information about their impact on current practice and more explicit guidelines may aid decisions about the use of these resource-intensive infection control practices.

Contamination Relative to the Activation Timing of Filtered-Exhaust Helmets

BACKGROUND

Filtered-exhaust helmet systems are commonplace during total joint arthroplasty, but their ability to limit intraoperative contamination has been questioned. We hypothesized that activation of the airflow system after complete gowning would lead to decreased contamination of the surgical environment.

METHODS

Using a fluorescent particle model, the maximal particle spread from a filtered-exhaust helmet and contamination of the surgical environment based on timing of airflow activation through simulated surgical gowning procedures were evaluated.

RESULTS

Helmet airflow analysis revealed particle spread greater than 5 feet in all trials. Activation before gowning resulted in a significantly greater contamination in the control group compared with the experimental group (P = .014).

CONCLUSIONS

We recommend complete surgical gowning before activation of the airflow system.

Do 'Surgical Helmet Systems' or 'Body Exhaust Suits' Affect Contamination and Deep Infection Rates in Arthroplasty? A Systematic Review

This systematic review examined whether negative-pressure Charnley-type body exhaust suits (BES) or modern positive-pressure surgical helmet systems (SHS) reduce deep infection rates and/or contamination in arthroplasty. For deep infection, four studies (3990 patients) gave adjusted relative risk for deep infection of 0.11 (P = 0.09) against SHS. Five of 7 (71%) studies found less air contamination and 2 of 4 studies (50%) less wound contamination with BES. One of 4 (25%) found less air contamination with SHS and 0 of 1 (0%) less wound contamination. In contrast to BES, modern SHS designs were not shown to reduce contamination or deep infection during arthroplasty.

Intraoperative contamination and space suits: a potential mechanism

The body exhaust suit (BES) of Charnley creates 'negative pressure' inside the gown using intake/outtake tubing. Modern 'space suit' (SS) systems incorporate helmet-based intake fans, which use the hood material as a filter and create 'positive pressure' inside the gown. While early studies of BES demonstrate a clear reduction in infection rates following arthroplasty, recent clinical data on SS use has paradoxically reported a marked increase. We hypothesized that the positive pressure inside the gown could carry air and particles via the unsealed area around the surgeon's cuff into the operative field. We performed 12 simulated operations with the surgeons hands covered in fluorescent 0.5 micron powder that approximates the size of shedded skin squames. Photographs under UV light and air particle counts were used to compare potential contamination rates between SS and conventional gowns using a standardised scoring system. The highest powder migration was seen in the SS group with a score of 15.3 out of 28. No powder migration was seen in the standard gown group (p = 0.028). This study provides a plausible explanation for the increase in infection rates seen with SS use. We recommend SS be considered for personal protection only and supplemented with sealant tape around the inner glove.

Transmission and prevention of occupational infections in orthopaedic surgeons

Microorganisms are transmitted in hospitals mainly by contact, droplet, and airborne routes. Orthopaedic surgeons have a substantial occupational risk of contracting a blood-borne infection because of frequent handling of sharp instruments and objects during operative procedures. Aerosolization means the formation of aerosols and droplets when blood or other body fluids are mechanically disturbed. Smaller particles (<5 microm) will remain suspended in air. Pathogens that can survive in these small airborne particles may cause infection if they are inhaled. Aerosol-generating procedures in patients with tuberculosis or severe acute respiratory syndrome (SARS) may facilitate airborne transmission. The Hospital Infection Control Practices Advisory Committee and the Centers for Disease Control and Prevention have established guidelines for isolation precautions in hospitals.

Airborne coagulase negative staphylococci produced by a sewage treatment plant

Since some coagulase-negative staphylococci species are involved in clinical and environmental situations, the authors carried out a study on the spread of these bacteria in the air of a sewage treatment plant. For these purposes a total of 196 samples were taken from 16 sampling stations, 11 during the day and 5 at night (only at 4 points), using the settle plate technique. Altogether 13 species of coagulase negative staphylococci were isolated: S. haemolyticus, S. xylosus and S. cohnii were particularly common. Station no. 2 (an area almost always kept closed containing the fine screens) was found to be the most contaminated. The presence of coagulase negative staphylococci was favoured by high temperatures and low humidity. No differences were found due to variations in wind speed and direction or between day and night.