Handheld vital microscopy for the identification of microcirculatory alterations in cervical intraepithelial neoplasia and cervical cancer

BACKGROUND

Ninety percent of cervical cancer (CC) diagnoses and deaths occur in low and middle-income countries (LMICs). Especially in these countries, where human and material resources are limited, there is a need for real-time screening methods that enable immediate treatment decisions (i.e., 'see and treat').

OBJECTIVE

To evaluate whether handheld vital microscopy (HVM) enables real-time detection of microvascular alterations associated with cervical intraepithelial neoplasia (CIN) and CC.

METHODS

A cross-sectional study was conducted in an oncologic hospital and outpatient clinic, and included ten healthy controls, ten women with CIN, and ten women with CC. The microvasculature was assessed in four quadrants of the uterine cervix using HVM. The primary outcome was the presence of abnormal angioarchitecture (AA). Secondary outcomes included capillary loop density (CD), total vessel density (TVD), functional capillary density (FCD), and the proportion of perfused vessels (PPV).

RESULTS

198 image sequences of the cervical microvasculature were recorded. Compared to healthy controls, significantly more abnormal image sequences were observed in women with high-grade CIN (11 % vs. 44 %, P < 0.001) and women with CC (11 % vs. 69 %, P < 0.001). TVD, FCD, and PPV were lower in women with CIN and CC.

CONCLUSIONS

HVM enables easy, real-time, non-invasive assessment of cervical lesions through the detection of microvascular alterations. Thereby, HVM potentially provides an opportunity for point-of-care screening, which may enable immediate treatment decisions (see and treat) and reduce the number of unnecessary surgical interventions.

The future of intensive care: the study of the microcirculation will help to guide our therapies

The goal of hemodynamic resuscitation is to optimize the microcirculation of organs to meet their oxygen and metabolic needs. Clinicians are currently blind to what is happening in the microcirculation of organs, which prevents them from achieving an additional degree of individualization of the hemodynamic resuscitation at tissue level. Indeed, clinicians never know whether optimization of the microcirculation and tissue oxygenation is actually achieved after macrovascular hemodynamic optimization. The challenge for the future is to have noninvasive, easy-to-use equipment that allows reliable assessment and immediate quantitative analysis of the microcirculation at the bedside. There are different methods for assessing the microcirculation at the bedside; all have strengths and challenges. The use of automated analysis and the future possibility of introducing artificial intelligence into analysis software could eliminate observer bias and provide guidance on microvascular-targeted treatment options. In addition, to gain caregiver confidence and support for the need to monitor the microcirculation, it is necessary to demonstrate that incorporating microcirculation analysis into the reasoning guiding hemodynamic resuscitation prevents organ dysfunction and improves the outcome of critically ill patients.

Real-time observation of microcirculatory leukocytes in patients undergoing major liver resection

Ischemia/reperfusion injury and inflammation are associated with microcirculatory dysfunction, endothelial injury and glycocalyx degradation. This study aimed to assess microcirculation in the sublingual, intestinal and the (remnant) liver in patients undergoing major liver resection, to define microcirculatory leukocyte activation and its association with glycocalyx degradation. In this prospective observational study, the microcirculation was assessed at the beginning of surgery (T0), end of surgery (T1) and 24 h after surgery (T2) using Incident Dark Field imaging. Changes in vessel density, blood flow and leukocyte behaviour were monitored, as well as clinical parameters. Syndecan-1 levels as a parameter of glycocalyx degradation were analysed. 19 patients were included. Sublingual microcirculation showed a significant increase in the number of rolling leukocytes between T0 and T1 (1.5 [0.7-1.8] vs. 3.7 [1.7-5.4] Ls/C-PCV/4 s respectively, p = 0.001), and remained high at T2 when compared to T0 (3.8 [3-8.5] Ls/C-PCV/4 s, p = 0.006). The microvascular flow decreased at T2 (2.4 ± 0.3 vs. baseline 2.8 ± 0.2, respectively, p < 0.01). Duration of vascular inflow occlusion was associated with significantly higher numbers of sublingual microcirculatory rolling leukocytes. Syndecan-1 increased from T0 to T1 (42 [25-56] vs. 107 [86-164] ng/mL, p < 0.001). The microcirculatory perfusion was characterized by low convection capacity and high number of rolling leukocytes. The ability to sublingually monitor the rolling behaviour of the microcirculatory leukocytes allows for early identification of patients at risk of increased inflammatory response following major liver resection.

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.

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.

The vulnerable microcirculation in the critically ill pediatric patient

In neonates, cardiovascular system development does not stop after the transition from intra-uterine to extra-uterine life and is not limited to the macrocirculation. The microcirculation (MC), which is essential for oxygen, nutrient, and drug delivery to tissues and cells, also develops. Developmental changes in the microcirculatory structure continue to occur during the initial weeks of life in healthy neonates. The physiologic hallmarks of neonates and developing children make them particularly vulnerable during critical illness; however, the cardiovascular monitoring possibilities are limited compared with critically ill adult patients. Therefore, the development of non-invasive methods for monitoring the MC is necessary in pediatric critical care for early identification of impending deterioration and to enable the initiation and titration of therapy to ensure cell survival. To date, the MC may be non-invasively monitored at the bedside using hand-held videomicroscopy, which provides useful information regarding the microcirculation. There is an increasing number of studies on the MC in neonates and pediatric patients; however, additional steps are necessary to transition MC monitoring from bench to bedside. The recently introduced concept of hemodynamic coherence describes the relationship between changes in the MC and macrocirculation. The loss of hemodynamic coherence may result in a depressed MC despite an improvement in the macrocirculation, which represents a condition associated with adverse outcomes. In the pediatric intensive care unit, the concept of hemodynamic coherence may function as a framework to develop microcirculatory measurements towards implementation in daily clinical practice.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Monitoring the microcirculation at the bedside using hand-held imaging microscopes: Automatic tracking of erythrocytes

In recent years, the development of portable microscopy devices that enable the noninvasive bedside evaluation of the mucosal microcirculation in critically ill patients has expanded the research on this level of the cardiovascular system. Several semi-quantitative scores have been defined to assess the peripheral perfusion, based on videos of the microcirculation. However, they are cumbersome and time-consuming processes, highlighting the need for the development of automated software techniques, to reduce physicians workload and ensure prompt and objective patient evaluation. We developed a rapid, automatic method for the quantitative assessment of erythrocyte velocities in Incident Dark Field (IDF) illumination videos of capillary flow. The technique, based on Kalman filter object tracking, was tested in 35 IDF videos against space-time diagrams, showing high correlation (r = 0.96) and agreement (bias = 3.3 μm/s) with space-time diagrams (STD), below 200 μm/s.

Arterial lactate for predicting mortality in children requiring extracorporeal membrane oxygenation

BACKGROUND

Dynamic arterial lactate indices predict mortality more accurately than static arterial lactate measurements in children with septic shock or congenital cardiac defects. The current study evaluates whether this also applies to children with primary respiratory disease requiring extracorporeal membrane oxygenation (ECMO).

METHODS

Static arterial lactate levels (LACabs) were prospectively collected before and during ECMO support for this single center, observational cohort study. Also, time-weighted arterial lactate (LACtw) and lactate change over time (LACdelta) were calculated as dynamic indices for, respectively, the duration and the trend over time of lactate derangement. Intensive care mortality was the primary endpoint. Analyses were performed for neonatal and pediatric patients separately.

RESULTS

Fifty-six neonatal and 39 pediatric patients were included. Eighteen (32%) neonatal and 12 (31%) pediatric patients died. The evolution of LACabs and LACdelta differed between the pediatric survivors and the pediatric non-survivors (P<0.001, P=0.025). The hazard ratio was 1.23 (CI95=1.06-1.43, P=0.007) for LACabs and 20.64 (CI95=1.99-214.20, P=0.011) for LACdelta, indicating that higher lactate levels increase the risk for mortality. The predictive value for LACabs was 0.75 (CI95=0.57-0.93) and for LACdelta 0.69 (CI95=0.51-0.87), respectively. There were neither consistent differences for LACtw in the pediatric patients, nor for any of the static or dynamic lactate indices in the neonatal patients.

CONCLUSION

Static arterial lactate measurements and, to a lesser extent, dynamic arterial lactate indices predict mortality in pediatric, but not neonatal ECMO patients. The magnitude and trend over time rather than the duration of lactate derangement are associated with mortality.

Rectal microcirculatory alterations after elective on-pump cardiac surgery

BACKGROUND

Hemodynamic changes, related to on-pump cardiac surgery, have been reported to impair intestinal perfusion. However, until recently, direct in vivo observation of the intestinal microcirculation was not clinically feasible, and the concept of altered intestinal blood flow in the setting of cardiac surgery depended on indirect observations from other techniques, such as tonometry and microdialysis. To establish the incidence of intestinal microvascular alterations after cardiac surgery, we performed direct in vivo observation of the microcirculation in a clinically accessible part of the intestinal tract in this setting.

METHODS

A single-center prospective observational study was conducted in postoperative elective on-pump cardiac surgery patients. Simultaneously, sidestream dark field (SDF) imaging and automated gas tonometry were performed in the rectal pouch within 30 minutes after ICU admission.

RESULTS

The rectal median microvascular flow index was 3(3-3) and the proportion of perfused vessels (PPV) was 85% (72-93). The median rectal-to-arterial partial carbon dioxide pressure difference (ΔPCO(2)) was 1.5 (-1.5-8.3) mmHg; 6 (21%) patients had a ΔPCO(2)> 8.3 mmHg, among them 2 (7%) with values> 10.5 mmHg.

CONCLUSION

After elective on-pump cardiac surgery, direct in vivo observation of rectal mucosa revealed a PPV <90% in 54% of all patients. At the same time, rectal microcirculatory blood flow appeared to be unaltered. Combining rectal SDF imaging with rectal tonometry revealed a 7% incidence of rectal-to-arterial pCO(2) gap >1.4,kPa, suggesting non-dysoxic perfusion in the majority of patients, despite the observed percentage of non-perfused crypts.

Functional capillary density decreases after the first week of life in term neonates

BACKGROUND

Changes in the microcirculation have been recognized to play a crucial role in many disease processes. In premature neonates, functional capillary density (FCD) decreases during the first months of life.

OBJECTIVES

The aims of this study were to obtain microcirculatory parameters in term neonates and older children who did not present with compromised respiration or circulation and to determine developmental changes in the microcirculation in young children.

METHODS

This single-center prospective observational study was performed at a level III university children's hospital. Subjects eligible for inclusion were children up to the age of 3 years who did not have any respiratory compromise, circulatory compromise or signs of dehydration. The buccal mucosa of 45 children was assessed, using orthogonal polarization spectral imaging.

RESULTS

We found a significantly higher FCD in neonates younger than 1 week compared with older children. The median FCD was 8.1 cm/cm(2) (range 7.3-9.4) for 0- to 7-day-old neonates (n = 12), 6.9 cm/cm(2) (range 4.7-8.7) for 8- to 28-day-olds (n = 10), 7.3 cm/cm(2) (range 6.1-8.8) for 1- to 6-month-olds (n = 19) and 6.7 cm/cm(2) (range 6.5-9.2) for 3-year-olds (n = 4). After the first week, there was no significant correlation between age and FCD.

CONCLUSION

FCD of the buccal mucosa decreases after the first week of life.

Measurement of functional microcirculatory geometry and velocity distributions using automated image analysis

This study describes a new method for analyzing microcirculatory videos. It introduces algorithms for quantitative assessment of vessel length, diameter, the functional microcirculatory density distribution and red blood-cell (RBC) velocity in individual vessels as well as its distribution. The technique was validated and compared to commercial software. The method was applied to the sublingual microcirculation in a healthy volunteer and in a patient during cardiac surgery. Analysis time was reduced from hours to minutes compared to previous methods requiring manual vessel identification. Vessel diameter was detected with high accuracy (>80%, d > 3 pixels). Capillary length was estimated within 5 pixels accuracy. Velocity estimation was very accurate (>95%) in the range [2.5, 1,000] pixels/s. RBC velocity was reduced by 70% during the first 10 s of cardiac luxation. The present method has been shown to be fast and accurate and provides increased insight into the functional properties of the microcirculation.

Direct in vivo assessment of microcirculatory dysfunction in severe falciparum malaria

BACKGROUND

This study sought to describe and quantify microcirculatory changes in the mucosal surfaces of patients with severe malaria, by direct in vivo observation using orthogonal polarization spectral (OPS) imaging.

METHODS

The microcirculation in the rectal mucosa of adult patients with severe malaria was assessed by use of OPS imaging, at admission and then daily. Comparison groups comprised patients with uncomplicated falciparum malaria, patients with bacterial sepsis, and healthy individuals.

RESULTS

Erythrocyte velocities were measured directly in 43 adult patients with severe falciparum malaria, of whom 20 died. Microcirculatory blood flow was markedly disturbed, with heterogeneous obstruction that was proportional to severity of disease. Blocked capillaries were found in 29 patients (67%) and were associated with concurrent hyperdynamic blood flow (erythrocyte velocity, >750 mm/s) in adjacent vessels in 27 patients (93%). The proportion of blocked capillaries correlated with the base deficit in plasma and with the concentration of lactate. Abnormalities disappeared when the patients recovered. In healthy individuals and in patients with uncomplicated malaria or sepsis, no stagnant erythrocytes were detected, and, in patients with sepsis, hyperdynamic blood flow was prominent.

CONCLUSION

Patients with severe falciparum malaria show extensive microvascular obstruction that is proportional to the severity of the disease. This finding underscores the prominent role that microvascular obstruction plays in the pathophysiology of severe malaria and illustrates the fundamental difference between the microvascular pathophysiology of malaria and that of bacterial sepsis.