BMI and obesity
The finding that BMI poses a significant risk factor for developing an SSI following emergency CS is consistent with previous research demonstrating the negative impact on post-surgical infection risk29, 30, 25, 27, 26, Wloch et al.29 and Ghuman et al. 27 both cited impaired immune response, larger wound area size and poor perfusion of prophylactic antibiotics in obese individuals as possible reasons for this increased risk. One possible explanation is the pathophysiological role that BMI plays in emergency CS due to the decreased efficacy of excess adipose tissue on the immune system and a decrease in perioperative tissue deoxygenation. 32There is evidence to support this; in a meta-analysis of the use of perioperative supplemental oxygen therapy on the rate of SSI, Qadanet al. 33 found that administering supplemental oxygen following an operation had a significant effect in preventing the development of an SSI, possibly due to ‘oxidative killing’, which requires sufficient oxygen partial pressures in order to function. Metabolic and hormonal changes attributable to obesity have been cited as increasing the risk of infection 34 and impaired wound healing 35, 36, 37 suggesting that the physiological impact of an increased body mass compounds the body’s ability to recover following a surgical procedure. However, other studies have failed to substantiate these findings or indeed identify possible causes for the increased risk of infection in obese patients.25, 30 The impact of BMI on post-surgical outcomes has been recognised more widely in general surgery as a possible consequence of impaired wound healing due to increased volume of subcutaneous fat, increased tension on surgical incision and elevated blood glucose levels. 38 Impaired antibiotic performances and altered immune cell function 39, 40 as well as a larger surgical incision and more complex surgical procedure41 have also been cited as explanations for the increased risk of infection in obesity.