Validation of noninvasive focal depth measurements to determine epithelial thickness of the vaginal wall

Microcirculatory depth of focus measurement shows reduction of tissue edema by albumin resuscitation in burn patients

Background

Severe burns induce volume shifts via capillary leaks, eventually requiring massive fluid resuscitation and promoting tissue edema. Albumin may help to mitigate the edema, thereby improving perfusion. This study shows that sublingual microcirculation measurements can quantify both tissue perfusion and edema.

Methods

This prospective observational study was conducted between November 2018 and December 2019 in the intensive care unit of Maasstad Hospital Burn Center, Rotterdam, The Netherlands. Patients with severe burns affecting >15% of the total body surface area were included. Fluid management was conducted in accordance with the Parkland formula. Albumin (20%) was administered at a rate of 0.5 mL/(kg·h), starting 12 h after the burn incident. Alterations in the sublingual microcirculation, including capillary perfusion and density, were measured at admission (T0) and 4 h (T4) and 12 h (T12) after admission. Sublingual depth of focus (DOF) of the microcirculation was used to quantify the tissue edema.

Results

Nine patients were recruited with a mean total body surface area of 36% ± 23%. By T12, a median of 4085 mL (interquartile range [IQR]: 3714-6756 mL) of crystalloids and 446 mL (IQR: 176-700 mL) of 20% albumin were administered. The DOF increased significantly after crystalloid administration (T4 vs. T0, mean difference [MD]=27.4 µm, 95% confidence interval [CI]: 3.4 to 50.9, P=0.040). Following albumin administration, DOF significantly decreased (T12 vs. T4, MD=-76.4 µm, 95% CI: -116.6 to -36.1, P=0.002). Total vessel density decreased significantly with crystalloid administration (T4 vs. T0, MD=-3.5 mm/mm2, 95% CI: -5.7 to -1.4, P=0.004) but increased after albumin administration (T12 vs. T4, MD=6.2 mm/mm2, 95% CI: 3.2 to 9.3, P=0.001).

Conclusion

Sublingual microcirculation measurement of DOF and other parameters provide a valuable tool for the assessment of tissue perfusion and edema in patients with severe burns. Further investigation is required to evaluate the role of albumin in increasing microcirculatory convection and reducing tissue edema.

The Microcirculation of Vaginal Tissue in Women with Obstetric Vesicovaginal Fistula and Short-Term Effects of Surgical Repair on Microvascular Parameters

OBJECTIVES

The objective of the study was to better understand the extent of the ischemic trauma and the effects of surgical repair on the vaginal microcirculation in patients with obstetric vesicovaginal fistula (VVF).

DESIGN

In this observational study, we evaluated the vaginal microvasculature surrounding VVF using handheld vital microscopy (HVM) before, during, and 2 weeks after surgical VVF repair.

PARTICIPANTS

Seventeen women undergoing VVF repair were included in this study.

SETTING

The study was conducted in the Fistula Care Centre in Lilongwe, Malawi.

METHODS

We used HVM with incident dark-field imaging to non-invasively visualize the microvasculature of the vaginal tissue surrounding fistulas. The primary outcome was the presence of microvascular flow. Secondary outcomes included angioarchitecture, fistula closure (postoperative dye test), and urinary continence (pad weight test).

RESULTS

Microvascular flow was present before, during, and after surgical repair in, respectively, 83.8%, 83.9%, and 93.4% of obtained image sequences. The angioarchitecture was normal in 75.8% of the image sequences before surgery, 69.4% at fistula closure, and 89.1% two weeks after VVF repair. Fourteen (82.4%) patients had a closed fistula after surgical repair.

LIMITATIONS

The study was limited by the lack of a control group and the relatively small sample size.

CONCLUSION

Although the vaginal microcirculation in women with VVF is compromised, extensive ischemic damage is not observed in the tissue surrounding fistulas. This suggests significant regenerative capacity of the vaginal vasculature in young women, or less extensive ischemic damage than presumed. Following surgical repair, we observed improvement of microcirculatory flow and angioarchitecture, suggesting that surgery is a good option for patients with obstetric VVF.

Vaginal changes after ovariectomy in ewes: A large animal model for genitourinary syndrome of menopause

OBJECTIVE

To evaluate the effect of iatrogenic menopause on the physiology of the vagina of the ewe and to evaluate if vaginal changes in ewes can be translated to women with genitourinary syndrome of menopause (GSM).

METHODS

Preclinical research with Dohne Merino ewes. Iatrogenic menopause was induced by bilateral ovariectomy (OVX). Animals were randomized for surgery, blinded for allocation and outcome assessment. Differences between groups were determined by linear regression analyses at 5 months after OVX. Outcome measures were vaginal epithelial thickness, pH, vaginal maturation value, vaginal maturation index, epithelial glycogen accumulation, content of elastin fibers, collagen, and vascularity.

RESULTS

OVX ewes (n = 20) showed epithelial thinning of the vaginal wall from 146 μm to 47 μm (mean, P < 0.001). Furthermore, epithelial glycogen accumulation and vascularity of the vaginal wall significantly decreased (43% and 23%, respectively) as compared with the control group (no intervention; n = 5). No significant differences were found for other outcome measures.

CONCLUSION

This study established the ewe as a suitable large animal model for GSM. Furthermore, the similar relevant outcomes in humans and ewes hold great value for future translational research for the evaluation and optimization of different treatment modalities for GSM.

The effect of CO2 laser therapy on vaginal microcirculatory parameters in an animal model for genitourinary syndrome of menopause

BACKGROUND

Vaginal laser therapy for the treatment of genitourinary syndrome of menopause (GSM) has been introduced to the market with limited (pre)clinical and experimental evidence supporting its efficacy. It is suggested that vaginal laser therapy increases epithelial thickness and improves vascularization, but the underlying biological working mechanism has not been substantiated yet.

OBJECTIVE

To evaluate the effects of CO₂ laser therapy on vaginal atrophy using noninvasive incident dark field (IDF) imaging in a large animal model for GSM.

DESIGN, SETTING, AND PARTICIPANTS

An animal study was conducted between 2018 and 2019 and included 25 Dohne Merino ewes, of which 20 underwent bilateral ovariectomy (OVX) to induce iatrogenic menopause, and 5 did not. The total study duration was 10 months.

INTERVENTIONS

Five months after OVX, ovariectomized ewes received monthly applications of CO₂ laser (n = 7), vaginal estrogen (n = 7), or no treatment (n = 6) for 3 months. IDF imaging was performed monthly in all animals.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was the proportion of image sequences containing capillary loops (angioarchitecture). Secondary outcomes included focal depth (epithelial thickness), and quantitative measures of vessel density and perfusion. Treatment effects were evaluated using ANCOVA and binary logistic regression.

RESULTS AND LIMITATIONS

Compared to OVX-only, ewes treated with estrogen demonstrated a higher capillary loops proportion (4% vs. 75%, p < 0.01), and higher focal depth (60 (IQR 60-80) vs. 80 (IQR 80-80) p < 0.05). CO₂ laser therapy did not change microcirculatory parameters. As the ewes' vaginal epithelium is thinner than that of humans, it may demand different laser settings.

CONCLUSIONS

In a large animal model for GSM, CO₂ laser therapy does not affect microcirculatory outcomes related to GSM, whereas vaginal estrogen treatment does. Until more homogeneous and objective evidence about its efficacy is available, CO₂ laser therapy should not be adopted into widespread practice for treating GSM.

Laser versus sham for genitourinary syndrome of menopause: A randomised controlled trial

OBJECTIVE

To assess whether CO2 laser treatment is more effective than sham application in relieving the most bothersome symptom (MBS) in women with genitourinary syndrome of menopause (GSM).

DESIGN

Single-centre, sham-controlled, double-blind, randomised trial.

SETTING

A tertiary centre in Belgium.

POPULATION

Sixty women with moderate to severe GSM symptoms.

METHODS

All participants eventually received three consecutive laser and three consecutive sham applications, either first laser followed by sham, or conversely.

MAIN OUTCOME MEASURES

The primary outcome was the participant-reported change in severity of the MBS at 12 weeks. Secondary outcomes included subjective (patient satisfaction, sexual function, urinary function) and objective (pH, Vaginal Health Index Score, in vivo microscopy) measurements assessing the short-term effect and the longevity of treatment effects at 18 months after start of the therapy. Adverse events were reported at every visit.

RESULTS

The MBS severity score decreased from 2.86 ± 0.35 to 2.17 ± 0.93 (-23.60%; 95% CI -36.10% to -11.10%) in women treated with laser compared with 2.90 ± 0.31 to 2.52 ± 0.78 (-13.20%; 95% CI -22.70% to -3.73%) in those receiving sham applications (p = 0.13). There were no serious adverse events reported up to 18 months.

CONCLUSIONS

In women with GSM, the treatment response 12 weeks after laser application was comparable to that of sham applications. There were no obvious differences for secondary outcomes and no serious adverse events were reported.

Morphologic Mapping of the Sublingual Microcirculation in Healthy Volunteers

PURPOSE

Monitoring the sublingual and oral microcirculation (SM-OM) using hand-held vital microscopes (HVMs) has provided valuable insight into the (patho)physiology of diseases. However, the microvascular anatomy in a healthy population has not been adequately described yet.

METHODS

Incident dark field-based HVM imaging was used to visualize the SM-OM. First, the SM was divided into four different fields; Field-a (between incisors-lingua), Field-b (between the canine-first premolar-lingua), Field-c (between the first-second premolar-lingua), Field-d (between the second molar-wisdom teeth-lingua). Second, we investigated the buccal area, lower and upper lip. Total/functional vessel density (TVD/FCD), focus depth (FD), small vessel mean diameters (SVMDs), and capillary tortuosity score (CTS) were compared between the areas.

RESULTS

Fifteen volunteers with a mean age of 29 ± 6 years were enrolled. No statistical difference was found between the sublingual fields in terms of TVD (p = 0.30), FCD (p = 0.38), and FD (p = 0.09). SVMD was similar in Field-a, Field-b, and Field-c (p = 0.20-0.30), and larger in Field-d (p < 0.01, p = 0.015). The CTS of the buccal area was higher than in the lips.

CONCLUSION

The sublingual area has a homogenous distribution in TVD, FCD, FD, and SVMD. This study can be a description of the normal microvascular anatomy for future researches regarding microcirculatory assessment.

Ovariectomized mice and postmenopausal women exhibit analogous loss of genital epithelial integrity

Roughly half of all postmenopausal women are affected by the genitourinary syndrome of menopause (GSM). Symptoms of GSM, including vaginal irritation and dyspareunia, occur as reduced estrogen (E) production elicits loss of elasticity and other changes in genital tract tissue. While the use of the injectable contraceptive depot-medroxyprogesterone acetate (DMPA) likewise lowers serum E concentrations in reproductive age women and is associated with decreased genital levels of the cell-cell adhesion molecules desmoglein-1 (DSG1) and desmocollin-1 (DSC1) and impaired genital epithelial barrier function, the relevance of these findings to women in menopause is uncertain. Exploring the impact of menopause on genital epithelial integrity herein, we detected significantly lower levels of DSG1 and DSC1 in ectocervical tissue from menopausal and postmenopausal vs premenopausal women. Using ovariectomized (OVX) mice as a menopause model, we comparably saw significantly lower vaginal tissue levels of DSG1 and DSC1 in OVX mice vs. mice in estrus. Compared to estrus-stage mice and E-treated OVX mice, DMPA-treated ovary-intact mice and OVX mice also exhibited significantly reduced genital epithelial barrier function, greater susceptibility to genital herpes simplex virus type 2 infection, and delayed clearance of genital Chlamydia trachomatis infection. Current studies thus identify analogous loss of genital epithelial integrity in OVX mice and menopausal and postmenopausal women. By showing that loss of genital epithelial integrity is associated with increased mouse susceptibility to bacterial and viral pathogens, our findings also prioritize the need to resolve if reduced genital epithelial integrity in postmenopausal women is a significant risk factor for genital infection.

Automated quantification of tissue red blood cell perfusion as a new resuscitation target

PURPOSE OF REVIEW

Identification of insufficient tissue perfusion is fundamental to recognizing circulatory shock in critically ill patients, and the primary target to restore adequate oxygen delivery. However, the concept of tissue perfusion remains ill-defined and out-of-reach for clinicians as point-of-care resuscitation target. Even though handheld vital microscopy (HVM) provides the technical prerequisites to collect information on tissue perfusion in the sublingual microcirculation, challenges in image analysis prevent quantification of tissue perfusion and manual analysis steps prohibit point-of-care application. The present review aims to discuss recent advances in algorithm-based HVM analysis and the physiological basis of tissue perfusion-based resuscitation parameters.

RECENT FINDINGS

Advanced computer vision algorithm such as MicroTools independently quantify microcirculatory diffusion and convection capacity by HVM and provide direct insight into tissue perfusion, leading to our formulation a functional parameter, tissue red blood cell (RBC) perfusion (tRBCp). Its definition is discussed in terms of the physiology of oxygen transport to the tissue and its expected effect as a point-of-care resuscitation target. Further refinements to microcirculatory monitoring include multiwavelength HVM techniques and maximal recruitable microcirculatory diffusion and convection capacity.

SUMMARY

tRBCp as measured using algorithm-based HVM analysis with an automated software called MicroTools, represents a promising candidate to assess microcirculatory delivery of oxygen for microcirculation-based resuscitation in critically ill patients at the point-of-care.

Vaginal Er:YAG laser application in the menopausal ewe model: a randomised estrogen and sham-controlled trial

OBJECTIVE

To describe effects of non-ablative erbium-doped:yttrium-aluminium-garnet (Er:YAG) laser on vaginal atrophy induced by iatrogenic menopause in the ewe.

DESIGN

Animal experimental, randomised, sham and estrogen-treatment controlled study with blinding for primary outcome.

SETTING

KU Leuven, Belgium.

SAMPLE

Twenty-four ewes.

METHODS

Menopause was surgically induced, after which the ewes were randomised to three groups receiving vaginal Er:YAG laser application three times, with a 1-month interval; three sham manipulations with a 1-month interval; or estrogen replacement and sham manipulations. At given intervals, ewes were clinically examined and vaginal wall biopsies were taken. Vaginal compliance was determined by passive biomechanical testing from explants taken at autopsy.

MAIN OUTCOME MEASURES

Vaginal epithelial thickness (primary), composition of the lamina propria (collagen, elastin, glycogen and vessel content), vaginal compliance, clinical signs.

RESULTS

Animals exposed to Er:YAG laser application and sham manipulation, but not to estrogens, displayed a significant and comparable increase in vaginal epithelial thickness between baseline and 7 days after the third application (69% and 67%, respectively, both P < 0.0008). In laser-treated ewes, temporary vaginal discharge and limited thermal injury were observed. Estrogen-substituted ewes displayed a more prominent increase in epithelial thickness (202%; P < 0.0001) and higher vaginal compliance (P < 0.05). None of the interventions induced changes in the lamina propria.

CONCLUSIONS

Vaginal Er:YAG laser has comparable effect to sham manipulation in menopausal ewes.

TWEETABLE ABSTRACT

Vaginal Er:YAG laser has comparable effect to sham manipulation in menopausal ewes #LASER #GSM #RCT.

The vaginal microcirculation after prolapse surgery

Aims

Oxygen plays a crucial role in wound healing after prolapse surgery. Trauma to the vaginal vasculature might limit the delivery of oxygen to the surgical wound, which may negatively affect wound healing and regeneration of connective tissue. This possibly increases the future risk of recurrence. We aimed to determine the effects of vaginal prolapse surgery on the microcirculation of the vaginal wall.

Methods

We evaluated the vaginal microcirculation in healthy participants without known vascular disease undergoing anterior and/or posterior colporrhaphy. We used incident dark‐field imaging for in vivo assessment before and after (1 day, 2 weeks, and 6 weeks) surgery. We studied perfusion (microvascular flow index [MFI]), angioarchitecture (morphology/layout of microvessels) and capillary density.

Results

Ten women were included. Interindividual differences were observed 1 day postoperatively with regard to perfusion and angioarchitecture. Microvascular flow at the surgical site was absent or significantly reduced in some participants, whereas normal microvascular flow was observed in others (MFI range 0–3). Perfusion and angioarchitecture had been restored in all participants after 6 weeks (MFI range 2–3), regardless of the extent of vascular trauma 1 day postoperatively.

Conclusions

The difference in the extent of vascular trauma between women undergoing seemingly identical surgical procedures suggests that some individuals are more susceptible to vascular trauma than others. Delivery of oxygen to the wound and subsequent wound healing may be compromised in these cases, which could be related to the development of anatomical recurrence. Future studies should investigate whether there is a relationship between the vaginal microvasculature and the recurrence of prolapse.