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)