Can sidestream dark field (SDF) imaging identify subtle microvascular changes of the bowel during colorectal surgery?

BACKGROUND: Recognition of a non-viable bowel during colorectal surgery is a challenging task for surgeons. Identifying the turning point in serosal microcirculatory deterioration leading up to a non-viable bowel is crucial. The aim of the present study was to determine whether sidestream darkfield (SDF) imaging can detect subtle changes in serosal microcirculation of the sigmoid after vascular transection during colorectal surgery. METHODS: A prospective observational clinical study was performed at a single medical centre. All eligible participants underwent laparoscopic sigmoid resection and measurements were taken during the extra-abdominal phase. Microcirculation was measured at the transected bowel and 20 cm proximal to this point. Microcirculatory parameters such as Microvascular Flow Index (MFI), proportion of perfused vessels (PPV), perfused vessel density (PVD), total vessel density (TVD) and the Heterogeneity Index were determined. Data are presented as median (interquartile range) or mean ± standard deviation. RESULTS: A total of 60 SDF images were acquired for 10 patients. Perfusion parameters and perfused vessel density were significantly lower at the transected bowel compared with the non-transected measurements [MFI 2.29 (1.96-2.63) vs 2.96 (2.73-3.00), p = 0.007; PPV 74% (55-83) vs 94% (86-97), p = 0.007; and PVD 7.61 ± 2.99 mm/mm2 versus 10.67 ± 1.48 mm/mm2, p = 0.009]. Total vessel density was similar between the measurement locations. CONCLUSIONS: SDF imaging can identify changes of the bowel serosal microcirculation. Significantly lower serosal microcirculatory parameters of the vascular transected bowel was seen compared with the non-transected bowel. The ability of SDF imaging to detect subtle differences holds promise for future research on microvascular cut-off values leading to a non-viable bowel.

Effects of Thoracic Epidural Anaesthesia on the Serosal Microcirculation of the Human Small Intestine.

BACKGROUND: The effect of thoracic epidural analgesia (TEA) on splanchnic blood flow during abdominal surgery remains unclear. The purpose of this study was to examine whether the hemodynamic effects of TEA resulted in microcirculatory alterations to the intestinal serosa, which was visualized using incident dark-field (IDF) videomicroscopy. METHODS: An observational cohort study was performed. In 18 patients, the microcirculation of the intestinal serosa was visualized with IDF. Microcirculatory and hemodynamic measurements were performed prior to (T1) and after administering a bolus of levobupivacaine (T2). If correction of blood pressure was indicated, a third measurement was performed (T3). The following microcirculatory parameters were calculated: microvascular flow index, proportion of perfused vessels, perfused vessel density and total vessel density. Data are presented as median [IQR]. RESULTS: Mean arterial pressure decreased from 73 mmHg (68-83) at T1 to 63 mmHg (±11) at T2 (p = 0.001) with a systolic blood pressure of 114 mmHg (98-128) and 87 (81-97), respectively (p = 0.001). The microcirculatory parameters of the bowel serosa, however, were unaltered. In seven patients, blood pressure was corrected to baseline values from a MAP of 56 mmHg (55-57), while microcirculatory parameters remained constant. CONCLUSION: We examined the effects of TEA on the intestinal serosal microcirculation during abdominal surgery using IDF imaging for the first time in patients. Regardless of a marked decrease in hemodynamics, microcirculatory parameters of the bowel serosa were not significantly affected. TRIAL REGISTRY NUMBER: ClinicalTrials.gov identifier NCT02688946.

Sidestream dark field imaging of the serosal microcirculation during gastrointestinal surgery.

AIM: The study aimed to describe the serosal microcirculation of the human bowel using sidestream dark field imaging, a microscopic technique using polarized light to visualize erythrocytes through capillaries. We also compared its feasibility to the current practice of sublingual microcirculatory assessment. METHOD: In 17 patients sidestream dark field measurements were performed during gastrointestinal surgery. Microcirculatory parameters like microvascular flow index (MFI), proportion of perfused vessels (PPV), perfused vessel density (PVD) and total vessel density (TVD) were determined for every patient, sublingually and on the bowel serosa. RESULTS: Sixty measurements were done on the bowel of which eight (13%) were excluded, five owing to too much bowel peristalsis and three because of pressure artefacts. Image stability was in favour of sublingual measurements [pixel loss per image, bowel 145 (95% CI 126-164) vs sublingual 55 (95% CI 41-68); P < 0.001] and time to acquire a stable image [bowel 96 s (95% CI 63-129) vs. sublingual 46 s (95% CI 29-64); P = 0.013]. No difference in the MFI was observed [bowel 2.9 (interquartile range 2.87-2.95) vs sublingual 3.0 (interquartile range 2.91-3.0); P = 0.081]. There was a difference in the PPV [bowel 95% (95% CI 94-96) vs sublingual 97% (95% CI 97-99); P < 0.001], PVD [bowel 12.9 mm/mm2 (95% CI 11.1-14.8) vs sublingual 17.4 mm/mm2 (95% CI 15.6-19.1); P = 0.003] and the TVD [bowel 13.6 mm/mm2 (95% CI 11.6-15.6) vs sublingual 17.7 mm/mm2 (95% CI 16.0-19.4); P = 0.008]. CONCLUSION: Sidestream dark field imaging is a very promising technique for bowel microcirculatory visualization and assessment. It is comparable to sublingual assessment and the analysis produces a similar outcome with slightly differing anatomical features.

Local application of gentamicin collagen implants in the prophylaxis of surgical site infections following gastrointestinal surgery: a review of clinical experience.

BACKGROUND: Surgical site infection (SSI) is a common type of healthcare-associated infection in gastrointestinal (GI) surgical procedures, which often has major consequences for patient recovery and increased healthcare costs due to prolonged hospital stay. This article provides an overview of the efficacy and safety of prophylactic application of resorbable gentamicin-containing collagen implants (GCI) in the prevention of SSI following high-risk GI surgical procedures. METHOD: Nine publications were identified using the PubMed online database and search terms 'gentamicin collagen implant' plus 'surgical site infection', 'wound infection' and 'gastrointestinal surgery'. RESULTS: Data from 483 patients treated prophylactically have demonstrated that GCI can reduce the wound infection rate in high-risk GI surgical procedures and improve wound healing after pilonidal sinus excision. In a study of 221 patients who underwent colorectal surgery, the wound infection rate was reduced to 5.6% in the GCI group compared to 18.4% in the control group (P < 0.01). GCI also positively influences the post-operative course for patients undergoing particularly risky procedures e.g. abdominoperineal resection (APR) combined with neoadjuvant radiotherapy. In one such patient series, GCI reduced the wound infection rate by over 70% and the length of hospital stay by 40%. Few side effects of GCI were noted in the 9 clinical studies. CONCLUSIONS: This review demonstrates that GCI can have a positive effect on wound infection rates in high-risk GI surgery and can also improve wound healing after pilonidal sinus excision.

The impact of chronic smoking on rectal mucosal blood flow.

BACKGROUND: Chronic smoking adversely affects peripheral vasculature. The aim of the present study was to investigate the effect of chronic cigarette smoking on rectal microvascular blood flow. METHODS: Rectal mucosal blood flow (MBF) was measured in 80 subjects (44 smokers and 36 non-smokers). The MBF was measured in the four quadrants of the rectum by laser Doppler flowmetry. RESULTS: Rectal perfusion was found to be significantly lower in posterior midline compared to the other sites. In chronic smokers the observed MBF measured at the posterior and ventral sites was significantly lower compared to non-smokers (P = 0.04 and P = 0.03, respectively). CONCLUSIONS: Our results suggest that rectal mucosal blood flow is reduced in chronic smokers.

Local gentamicin reduces perineal wound infection after radiotherapy and abdominoperineal resection.

BACKGROUND: Perineal wound complications are frequently observed after abdominoperineal resection (APR) for rectal cancer, especially in preoperatively irradiated patients. This is the first study to investigate whether local application of gentamicin-impregnated collagen fleece reduces deep perineal wound infection after APR for rectal cancer following short-term radiotherapy. METHODS: Between 2003 and 2007, a consecutive series of 40 patients underwent an APR for rectal cancer after short-course radiotherapy in our hospital. Of these patients, 19 received supplementary application of three reabsorbable gentamicin-impregnated collagen fleece sponges into the sacral cavity before closure of the perineum (group A), and 21 patients underwent primary closure of the perineal wound and served as a control group (group B). All patients received sacral drainage. A superficial perineal wound infection was defined as cellulitis with no evidence of deep tissue infection. A deep perineal wound infection was defined as skin and subcutaneous tissue breakdown with infection extending deep into the subcutaneous tissue or a wound abscess. RESULTS: The two groups were comparable regarding age, sex, tumour stage and level of the tumour. No postoperative mortality was observed in either group. Primary wound healing occurred in 16 patients (84%) in the gentamicin group and 9 patients (43%%) in the control group (p=0.01). The incidences of superficial perineal wound complications were 11% (two patients) in group A who received local application of gentamicin and 29% (six patients) in group B (p=0.15). Six patients (29%) in group B developed a deep infection or wound abscess, resulting in full dehiscence of the wound and sacral cavity. This devastating complication occurred in only one patient (5%) in group A (p=0.05). In most patients deep perineal wound infection was treated with vacuum therapy or drainage. The mean hospital stay of the gentamicin group was 15 days and of the control group 25 days (p=0.04). CONCLUSIONS: Based on the results of this study, we recommend local application of gentamicin in the sacral cavity in patients who undergo abdominoperineal resection after shortterm radiotherapy.

Preoperative chemoradiation with capecitabine in locally advanced rectal cancer.

BACKGROUND: Preoperative radiation therapy in combination with 5-fluoracil (5-FU) improves local tumour control in locally advanced rectal cancer. The aim of our study was to evaluate the toxicity and efficacy of preoperative chemoradiation using the oral 5-FU prodrug capecitabine in locally advanced rectal cancer. METHODS: Sixty patients with locally advanced rectal cancer were treated with preoperative chemoradiation. Radiotherapy consisted of a total dose of 50 Gy delivered in 25 fractions to the pelvis. Chemotherapy was concurrently administered and consisted of oral capecitabine only on radiotherapy days. Surgery was performed six to ten weeks after completion of chemoradiation. RESULTS: The patient population consisted of 19 females and 41 males, with a median age of 61 years. All but two patients received the full dose of chemoradiation. No grade 3 or 4 haematological toxicities developed. Two patients (3%) developed grade 3 radiation dermatitis and one a grade 3 diarrhoea. All patients underwent definitive surgery; 19 patients underwent an abdominal perineal resection (APR), 25 a low anterior resection (LAR) and 16 patients a Hartmann's procedure. One patient with a low anterior resection developed an anastomotic leakage (4%). Final pathology demonstrated eight patients (13%) with a complete pathological response. Primary tumour and nodal downstaging occurred in 67 and 84% of the patients, respectively. Two patients (3%) had an R1 resection, one after an APR and one after an LAR. CONCLUSION: Preoperative chemoradiation with oral capecitabine is safe and well tolerated in locally advanced rectal cancer patients. This preoperative treatment has a considerable downstaging effect on the tumour and lymph nodes.