Patients with chronic mesenteric ischemia have an altered sublingual microcirculation

Identifying a sublingual triangle as the ideal site for assessment of sublingual microcirculation

The sublingual mucosa is a commonly used intraoral location for identifying microcirculatory alterations using handheld vital microscopes (HVMs). The anatomic description of the sublingual cave and its related training have not been adequately introduced. The aim of this study was to introduce anatomy guided sublingual microcirculatory assessment. Measurements were acquired from the floor of the mouth using incident dark-field (IDF) imaging before (T0) and after (T1) sublingual cave anatomy instructed training. Instructions consists of examining a specific region of interested identified through observable anatomical structures adjacent and bilaterally to the lingual frenulum which is next to the sublingual papilla. The anatomical location called the sublingual triangle, was identified as stationed between the lingual frenulum, the sublingual fold and ventrally to the tongue. Small, large, and total vessel density datasets (SVD, LVD and TVD respectively) obtained by non-instructed and instructed measurements (NIN (T0) and IM (T1) respectively) were compared. Microvascular structures were analyzed, and the presence of salivary duct-related microcirculation was identified. A total of 72 video clips were used for analysis in which TVD, but not LVD and SVD, was higher in IM compared to NIM (NIM vs. IM, 25 ± 2 vs. 27 ± 3 mm/mm2 (p = 0.044), LVD NIM vs. IM: 7 ± 1 vs. 8 ± 1mm/mm2 (p = 0.092), SVD NIM vs. IM: 18 ± 2 vs. 20 ± 3 mm/mm2 (p = 0.103)). IM resulted in microcirculatory assessments which included morphological properties such as capillaries, venules and arterioles, without salivary duct-associated microcirculation. The sublingual triangle identified in this study showed consistent network-based microcirculation, without interference from microcirculation associated with specialized anatomic structures. These findings suggest that the sublingual triangle, an anatomy guided location, yielded sublingual based measurements that conforms with international guidelines. IM showed higher TVD values, and future studies are needed with larger sample sizes to prove differences in microcirculatory parameters.

Case report: Early detection of mesenteric ischemia by intravital microscopy in a patient with septic shock

Gut ischemia is a frequent but underdiagnosed complication, especially in critically ill intensive care patients, and represents a special diagnostic challenge that can only be solved in an interdisciplinary manner. We report a case of a 54-year-old woman with acute mesenteric ischemia (AMI) as a cause of septic shock diagnosed by intravital microscopy (IVM) 2 days before visible necrotic changes in a multimodality approach. We show that intravital microscopy can be a serious alternative for the early diagnosis of mesenteric ischemia in the hands of the skilled. We use this case to discuss the value and clinical perspective of IVM in the intensive care setting.

[Clinical implications of chronic mesenteric ischemia in elderly and senile patients]

AIM

To evaluate the sensitivity and specificity of the clinical criteria for the diagnosis of chronic mesenteric ischemia in elderly and senile patients with mesenteric atherosclerosis.

MATERIALS AND METHODS

The study included 142 patients (82 men and 60 women). The median age of patients is 66.0 [62.0; 72.0] years.

RESULTS

According to MDCT atherosclerotic lesions of the abdominal aorta and its unpaired visceral branches were diagnosed in 105 (73.9%) patients. A combination of atherosclerosis of the celiac trunk and the superior mesenteric artery with the presence of hemodynamically insignificant stenosis was revealed. Hemodynamically significant atherosclerotic narrowing of at least one mesenteric artery was present in 15% of cases. Among them, a single vascular lesion was found in 6 patients (4.2%), a combination of hemodynamically significant lesions of two arteries in 15 (11%) patients. Depending on the clinical manifestations, all patients are divided into two groups: the first group 30 (21.1%) patients with the presence of symptoms characteristic of chronic mesenteric ischemia (CMI). The second group consisted of 112 (78.8%) patients without a characteristic triad of symptoms. The clinical symptom complex of СMI, including postprandial abdominal pain, intestinal dysfunction and progressive weight loss, as a diagnostic criterion showed low sensitivity 13.3% and specificity 77.9%. At the same time, the sensitivity of such a clinical combination as a combination of atherosclerosis of the arteries of the lower extremities, weight loss and abdominal pain syndrome with a severity of more than 5.5 points, with respect to the detection of hemodynamically significant stenoses of two or more mesenteric arteries was sensitivity 86.7%, specificity 74.0%.

Recruitment of non-perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

KEY POINTS

A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries. In the present study, we report that high altitude-induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance. Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude-related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis. The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success.

ABSTRACT

A high altitude (HA) stay is associated with an increase in sublingual capillary total vessel density (TVD), suggesting microvascular recruitment. We hypothesized that microvascular recruitment occurs independent of cardiac output changes, that it relies on haemodynamic changes within the microcirculation as opposed to structural changes and that microcirculatory function is related to individual performance at HA. In 41 healthy subjects, sublingual handheld vital microscopy and echocardiography were performed at sea level (SL), as well as at 6022 m (C2) and 7042 m (C3), during ascent to 7126 m within 21 days. Sublingual topical nitroglycerin was applied to measure microvascular reactivity and maximum recruitable TVD (TVD_NG ). HA exposure decreased resting cardiac output, whereas TVD (mean ± SD) increased from 18.81 ± 3.92 to 20.92 ± 3.66 and 21.25 ± 2.27 mm mm^-2 (P < 0.01). The difference between TVD and TVD_NG was 2.28 ± 4.59 mm mm^-2 at SL (P < 0.01) but remained undetectable at HA. Maximal TVD_NG was observed at C3. Those who reached the summit (n = 15) demonstrated higher TVD at SL (P < 0.01), comparable to TVD_NG in non-summiters (n = 21) at SL and in both groups at C2. Recruitment of sublingual capillary TVD to increase microcirculatory oxygen extraction capacity at HA was found to be an intrinsic mechanism of the microcirculation independent of cardiac output changes. Microvascular reactivity to topical nitroglycerin demonstrated that HA-related capillary recruitment is a functional response as opposed to a structural change. The performance of the vascular microcirculation needed to reach the summit was found to be associated with a higher TVD at SL and the ability to further increase TVD_NG upon ascent to extreme altitude.