The Effect of Heated CO2 Insufflation in Minimising Surgical Wound Contamination During Open Surgery

Annals of Biomedical Engineering, Apr 2018

The primary source of infections in open surgeries has been found to be bacteria and viruses carried into the surgical wound on the surfaces of skin particles shed by patients and surgical staff. In open cardiac surgeries, insufflation of the wound with carbon dioxide is used to limit the quantity of air able to enter into the heart, avoiding air embolisms when the heart is restarted. This surgical technique has been evaluated as a method of limiting the number of skin particles able to enter into the wound, using computational fluid dynamics (CFD) simulations and experimental testing. Spherical particles of 5.0 and 13.5 μm in diameter were used to simulate skin particles falling above a wound, travelling in air ventilation velocities of either 0.2 or 0.4 m/s, and with or without CO2 insufflation. The CFD simulations with CO2 included a diffuser placed in the wound and supplied with CO2 at a rate of 10 L/min. Experimental testing was completed under similar conditions. The results of CFD simulations and experimental testing showed CO2 insufflation can significantly limit the number of particles able to enter into the wound.

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The Effect of Heated CO2 Insufflation in Minimising Surgical Wound Contamination During Open Surgery

The Effect of Heated CO2 Insufflation in Minimising Surgical Wound Contamination During Open Surgery MONIKA BAUMANN 1 JOHN E. CATER 0 1 2 0 Department of Engineering Science, The University of Auckland , Private Bag 92019, Auckland 1142 , New Zealand 1 neering Science, The University of Auckland , Private Bag 92019, Auckland 1142 , New Zealand. Electronic mails: 2 Fisher & Paykel Healthcare Ltd , 15 Maurice Paykel Pl, East Tamaki, Auckland 2013 , New Zealand -The primary source of infections in open surgeries has been found to be bacteria and viruses carried into the surgical wound on the surfaces of skin particles shed by patients and surgical staff. In open cardiac surgeries, insufflation of the wound with carbon dioxide is used to limit the quantity of air able to enter into the heart, avoiding air embolisms when the heart is restarted. This surgical technique has been evaluated as a method of limiting the number of skin particles able to enter into the wound, using computational fluid dynamics (CFD) simulations and experimental testing. Spherical particles of 5.0 and 13.5 lm in diameter were used to simulate skin particles falling above a wound, travelling in air ventilation velocities of either 0.2 or 0.4 m/s, and with or without CO2 insufflation. The CFD simulations with CO2 included a diffuser placed in the wound and supplied with CO2 at a rate of 10 L/min. Experimental testing was completed under similar conditions. The results of CFD simulations and experimental testing showed CO2 insufflation can significantly limit the number of particles able to enter into the wound. Carbon dioxide; Surgical insufflation; Infection; Skin particles INTRODUCTION Hospital-acquired infections have been estimated to have cost the UK a minimum of 1 billion pounds per a year with 15,000 treatable infections and 5000 deaths occurring.9 A proportion of those infections and deaths were a result of infections acquired during surgery, with literature suggesting surgical site infection rates range from 0.8 to 16% in cardiac surgeries, to as high as 30% in abdominal surgeries.22,24 Antibiotic resistant strains of bacteria began to be found in the early 1960s and their prevalence in recent years has only increased, as has the need to develop new methods of stopping these infections from occurring.1,11 The primary source of infection in surgeries is commonly agreed to be bacteria and viruses such as staphylococcus epidermidis22 and staphylococcus aureus,23 carried on skin scales which once shed, have the possibility of entering into the surgical wound. Skin particles naturally flake off at an estimated rate of between 106 and 107 particles per a day.9 These particles are then dispersed into the air through natural and forced convection. The main method used to reduce the probability of airborne particles from entering into the wound, (aside from sterilising equipment and using sterile gloves and gowns), is to place downward ventilation above the operating table, forcing particles away from the operating area towards the outer edges of the room. While surgeons’ and staff bodies are mostly covered and typically hairnets (or equivalent) are used, skin is still exposed. For example, surgeon’s necks are often exposed, and the nature of surgery requires surgeons to lean over the wound. The presence of the surgeon intermittently leaning over the wound has been found to potentially increase wound contamination by a factor of 27 when compared to the surgeon placed away from the wound.25 Carbon dioxide has been used in cardiothoracic surgery to de-air the surgical cavity for the past 50 years, lowering the chance of air embolisms when the heart is restarted.16,21 More recently heated and humidified CO2 insufflation of an open wound has been utilised as a method of helping to reduce surgical site infections,18 maintain core temperature10 and improve tissue oxygenation.12 The aim of this study was to investigate the difference in wound contamination of skin particles with and without the use of warmed carbon dioxide to fill the wound during surgery through computational and experimental methods; (humidity has been excluded from the carbon dioxide to simplify the computational models). The source of the skin cells was not considered to be of interest. As such, a micro-environment around the surgical wound and ventilation above the wound were considered rather than the operating theatre as a whole. MATERIALS AND METHODS To evaluate the effectiveness of CO2 insufflation, ANSYS CFX 17.0TM2 was used to simulate a model of a standard wound (without carbon dioxide) and a wound with carbon dioxide insufflation. Ventilation above the operating table was included and the skin particles were introduced at the same location. Computational Fluid Dynamics Wound Model and Diffuser Creo ParametricTM19 was used to create the standard and the CO2 insufflated wound models. The wound geometry chosen was based on that used by Persson et al.,17 re (...truncated)


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Monika Baumann, John E. Cater. The Effect of Heated CO2 Insufflation in Minimising Surgical Wound Contamination During Open Surgery, Annals of Biomedical Engineering, 2018, pp. 1-11, DOI: 10.1007/s10439-018-2034-6