Subcutaneous perfusion before and during surgery in obese and nonobese patients

Abstract

Hypoxia at the surgical site impairs wound healing and oxidative killing of microbes. Surgical site infections are more common in obese patients. We hypothesized that subcutaneous oxygen tension (P sq O 2 ) would decrease substantially in both obese and non-obese patients following induction of anesthesia and after surgical incision. We performed a prospective observational study that enrolled obese and non-obese surgical patients and measured serial P sq O 2 before and during surgery. Seven morbidly obese and seven non-obese patients were enrolled. At baseline breathing room air, P sq O 2 values were not significantly different (p 5 0.66) between obese (6.8 kPa) and non-obese (6.5 kPa) patients. The targeted arterial oxygen tension (40 kPa) was successfully achieved in both groups with an expected significant increase in P sq O 2 (obese 16.1 kPa and non-obese 13.4 kPa; p 5 0.001). After induction of anesthesia and endotracheal intubation, P sq O 2 did not change significantly in either cohort in comparison to levels right before induction (obese 15.5, non-obese 13.5 kPa; p 5 0.95), but decreased significantly during surgery (obese 10.1, non-obese 9.3 kPa; p 5 0.01). In both morbidly obese and non-obese patients, P sq O 2 does not decrease appreciably following induction of anesthesia, but decreases markedly (33%) after commencement of surgery. Given the theoretical risks associated with low P sq O 2 , future research should investigate how P sq O 2 can be maintained after surgical incision.

Oxygenation of adipose tissue: A human perspective

“…It was found that morbidly obese individuals had lower pO 2 levels in subcutaneous WAT (sWAT) of the upper arm as compared to lean subjects, determined the morning after surgery . However, other studies in which sWAT oxygenation has been measured both during and after surgery showed opposite results, with increased or no significant difference in WAT pO 2 between obese and lean individuals . Notably, these initial studies assessed oxygenation in WAT of the upper arm, which is not of crucial importance for whole‐body metabolism.…”

Partial pressure of oxygen in adipose tissue and its relationship with fatness in a natural animal model of extreme fat deposition, the grey seal

“…Studies investigating adipose tissue Po 2 in rodents report a significant decrease of O 2 availability with increased fatness as well as increased expression of hypoxia-related genes, such as hypoxia-inducible transcription factor-1 alpha (HIF-1α) (Rausch et al, 2008;Ye et al, 2007). However, results in humans are inconsistent, with studies reporting similar (Hiltebrand et al, 2008;Kaiser et al, 2016), lower (Cifarelli et al, 2020;Kabon et al, 2004;Lawler et al, 2016;Pasarica et al, 2009), and higher (Goossens et al, 2011(Goossens et al, , 2018 adipose tissue Po 2 in obese compared to lean individuals. In addition, Vink et al (2017) report a decrease in adipose tissue Po 2 after diet-induced weight loss.…”