Interpatient heterogeneity in hepatic microvascular blood flow during vascular inflow occlusion (Pringle manoeuvre)

Assisted Fluid Management and Sublingual Microvascular Flow During High-Risk Abdominal Surgery: A Randomized Controlled Trial

BACKGROUND

Implementation of goal-directed fluid therapy (GDFT) protocols remains low. Protocol compliance among anesthesiologists tends to be suboptimal owing to the high workload and the attention required for implementation. The assisted fluid management (AFM) system is a novel decision support tool designed to help clinicians apply GDFT protocols. This system predicts fluid responsiveness better than anesthesia practitioners do and achieves higher stroke volume (SV) and cardiac index values during surgery. We tested the hypothesis that an AFM-guided GDFT strategy would also be associated with better sublingual microvascular flow compared to a standard GDFT strategy.

METHODS

This bicenter, parallel, 2-arm, prospective, randomized controlled, patient and assessor-blinded, superiority study considered for inclusion all consecutive patients undergoing high-risk abdominal surgery who required an arterial catheter and uncalibrated SV monitoring. Patients having standard GDFT received manual titration of fluid challenges to optimize SV while patients having an AFM-guided GDFT strategy received fluid challenges based on recommendations from the AFM software. In all patients, fluid challenges were standardized and titrated per 250 mL and vasopressors were administered to maintain a mean arterial pressure >70 mm Hg. The primary outcome (average of each patient's intraoperative microvascular flow index (MFI) across 4 intraoperative time points) was analyzed using a Mann-Whitney U test and the treatment effect was estimated with a median difference between groups with a 95% confidence interval estimated using the bootstrap percentile method (with 1000 replications). Secondary outcomes included SV, cardiac index, total amount of fluid, other microcirculatory variables, and postoperative lactate.

RESULTS

A total of 86 patients were enrolled over a 7-month period. The primary outcome was significantly higher in patients with AFM (median [Q1-Q3]: 2.89 [2.84-2.94]) versus those having standard GDFT (2.59 [2.38-2.78] points, median difference 0.30; 95% confidence interval [CI], 0.19-0.49; P < .001). Cardiac index and SVI were higher (3.2 ± 0.5 vs 2.7 ± 0.7 l.min-1.m-2; P = .001 and 42 [35-47] vs 36 [32-43] mL.m-2; P = .018) and arterial lactate concentration was lower at the end of the surgery in patients having AFM-guided GDFT (2.1 [1.5-3.1] vs 2.9 [2.1-3.9] mmol.L-1; P = .026) than patients having standard GDFT strategy. Patients having AFM received a higher fluid volume but 3 times less norepinephrine than those receiving standard GDFT (P < .001).

CONCLUSIONS

Use of an AFM-guided GDFT strategy resulted in higher sublingual microvascular flow during surgery compared to use of a standard GDFT strategy. Future trials are necessary to make conclusive recommendations that will change clinical practice.

The effect of the number of hepatic inflow occlusion times on the prognosis of ruptured hepatocellular carcinoma patients after hepatectomy

Background and aim

It has been previously reported that inflow occlusion does not affect postoperative outcomes in hepatocellular carcinoma patients. However, for patients with ruptured hepatocellular carcinoma(rHCC), the effect of hepatic inflow occlusion and the number of occlusion times on the prognosis is unknown.

Methods

203 patients with ruptured hepatocellular carcinoma were enrolled in this study. They were first divided into the non-hepatic inflow occlusion (non-HIO) group and the hepatic inflow occlusion (HIO) group. The Kaplan–Meier method was used to compare the recurrence-free survival and overall survival between the two groups. Patients in the HIO group were further divided into one-time HIO and two times HIO groups. KM method was also used to compare the two groups. Finally, independent risk factors affecting RFS and OS were determined by multivariate Cox regression analysis.

Result

In the non-HIO group, 1-,3- and 5-year OS rates were 67.0%, 41.0%, and 22.0%respectively, and RFS rates were 45.0%, 31.0%, and 20.0% respectively; In the one-HIO group, the 1-,3-, and 5-year OS rates were 55.1%, 32.1%, and 19.2% respectively, and RFS rates were 33.3%, 16.7%, and 7.7% respectively; In the two-HIO group, 1-,3-, and 5-year OS rates were 24.0%, 0.0%, and 0.0% respectively, and RFS rates were 8.0%, 0.0%, and 0.0% respectively. By Cox regression analysis, HIO was an independent risk factor for a poor prognosis in rHCC patients.

Conclusion

One time hepatic inflow occlusion did not affect postoperative OS, but negatively affected the RFS of rHCC patients; two times hepatic inflow occlusion negatively affected the postoperative OS and RFS in patients with rHCC.

New Noninvasive Methods to Evaluate Microvascular Structure and Function

The structural and functional alterations of microvessels are detected because of physiological aging and in several cardiometabolic diseases, including hypertension, diabetes, and obesity. The small resistance arteries of these patients show an increase in the media or total wall thickness to internal lumen diameter ratio (MLR or WLR), often accompanied by endothelial dysfunction. For decades, micromyography has been considered as a gold standard method for evaluating microvascular structural alterations through the measurement of MLR or WLR of subcutaneous small vessels dissected from tissue biopsies. Micromyography is the most common and reliable method for assessing microcirculatory endothelial function ex vivo, while strain-gauge venous plethysmography is considered the reference technique for in vivo studies. Recently, several noninvasive methods have been proposed to extend the microvasculature evaluation to a broader range of patients and clinical settings. Scanning laser Doppler flowmetry and adaptive optics are increasingly used to estimate the WLR of retinal arterioles. Microvascular endothelial function may be evaluated in the retina by flicker light stimulus, in the finger by tonometric approaches, or in the cutaneous or sublingual tissues by laser Doppler flowmetry or intravital microscopy. The main limitation of these techniques is the lack of robust evidence on their prognostic value, which currently reduces their widespread use in daily clinical practice. Ongoing and future studies will overcome this issue, hopefully moving the noninvasive assessment of the microvascular function and structure from bench to bedside.

Noninvasive, in vivo assessment of the cervical microcirculation using incident dark field imaging

AIM

This study evaluates the feasibility of handheld vital microscopy for noninvasive, objective assessment of the microcirculation of the human uterine cervix. We qualitatively and quantitatively describe the microcirculation in healthy subjects in order to provide a basis for its application in cervical pathology.

METHODS

Incident dark field imaging was used to image the microcirculation in four quadrants of the uterine ectocervix in ten healthy participants. If the squamocolumnar junction was visible, measurements were repeated on the endocervical columnar epithelium as well. Image acquisition time was recorded and participants scored the experienced level of discomfort. Angioarchitecture was classified according to Weber's classification. Quantitative parameters included capillary density (CD), total and perfused vessel density (TVD, PVD), proportion of perfused vessels (PPV) and microvascular flow index (MFI).

RESULTS

Image acquisition was easy, fast and well tolerated. Angioarchitecture was characterized by two distinctive and organized patterns; capillary loops underneath the squamous epithelium of the ectocervix and vascular networks underneath the columnar epithelium. In the image sequences containing capillary loops, mean CD was 33.2 cpll/mm² (95% CI 28.2-38.2 cpll/mm²). In the image sequences with vascular networks, mean TVD was 12.5 mm/mm² (95% CI 11.2-13.77 mm/mm²), mean PVD was 12.2 (95% CI 11.0-13.5 mm/mm²), MFI was 3 and PPV was 100%.

CONCLUSIONS

Incident dark field imaging allows for noninvasive, real time visualization and objective evaluation and quantification of the microcirculation of the uterine cervix. The organized vascular patterns and optimal perfusion observed in healthy subjects allow for comparison with cervical pathology, for example in patients with cervical dysplasia or cervical cancer.