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.

Intraoperative Imaging Techniques to Visualize Hepatic (Micro)Perfusion: An Overview.

The microcirculation plays a crucial role in the distribution of perfusion to organs. Studies have shown that microcirculatory dysfunction is an independent predictor of morbidity and mortality. Hence, assessment of liver perfusion offers valuable information on the (patho)physiological state of the liver. The current review explores techniques in perfusion imaging that can be used intraoperatively. Available modalities include dynamic contrast-enhanced ultrasound, handheld vital microscopes, indocyanine green fluorescence angiography, and laser contrast speckle imaging. Dynamic contrast-enhanced ultrasound relays information on deep tissue perfusion and is a commonly used technique to assess tumor perfusion. Handheld vital microscopes provide direct visualization of the sinusoidal architectural structure of the liver, which is a unique feature of this technique. Intraoperative fluorescence imaging uses indocyanine green, a dye that is administered intravenously to visualize microvascular perfusion when excited using near-infrared light. Laser speckle contrast imaging produces non-contact large surface-based tissue perfusion imaging free from movement- or pressure-related artefacts. In this review, we discuss the intrinsic advantages and disadvantages of these techniques and their clinical and/or scientific applications.

Alveolar Iodine Tampon Packing Reduces Postoperative Morbidity After Third Molar Surgery.

PURPOSE: The aim of this study was to assess the efficacy of an iodine tampon after mandibular third molar surgery on oral health-related quality of life (OHRQoL), use of painkillers, postoperative sequelae, and self-care behaviors in the first postoperative week. MATERIALS AND METHODS: This prospective, crossover, randomized controlled study included patients undergoing surgical removal of bilateral symmetrically, horizontally impacted mandibular third molars. The surgical site was randomly allocated to receive an iodine tampon after surgery or wound closure and rinsing with a Monoject syringe (Tyco/Healthcare-Kendall, Mansfield, MA). The primary outcomes measured each day during the first postoperative week were the Oral Health Impact Profile 14 score and postoperative sequelae, including pain, swelling, limited mouth opening, postoperative infection, and alveolar osteitis. The secondary outcome measures were several self-care behaviors. Data were analyzed using repeated-measures analysis of variance and paired-samples t tests. RESULTS: A total of 54 patients (25 men and 29 women; mean age, 25.1 years) were enrolled, with a total of 108 surgically removed impacted mandibular third molars. The use of an iodine tampon resulted in a significantly lower impact on OHRQoL (mean of 21.5 [standard deviation (SD), 9.6] vs 26.5 [SD, 10.6]) on the first postoperative day, which was observable until the seventh postoperative day. In addition, after removal of the impacted third molar, patients with the iodine tampon condition reported less pain (mean of 5.2 [SD, 1.9] vs 6.1 [SD, 2.1] on day 1, lasting throughout the week), less use of painkillers, less limited mouth opening, fewer problems chewing, less swelling, and earlier recovery. CONCLUSIONS: The use of postoperative iodine packing after the removal of impacted mandibular third molars significantly reduces OHRQoL and postoperative sequelae.

Imaging sublingual microcirculatory perfusion in pediatric patients receiving procedural sedation with propofol: A pilot study.

OBJECTIVE: Procedural sedation with propofol is widely used in the pediatric population. A well-known side effect of propofol is a decrease in peripheral vascular resistance resulting in hypotension, but little is known about the effects on microcirculation in humans. We aimed to evaluate the effects of propofol on the sublingual microcirculatory perfusion by continuous video imaging in pediatric patients undergoing procedural sedation. METHODS: Patients admitted to the Pediatric Intensive Care Unit for procedural sedation were recruited. Oral microcirculation was measured employing a continuous monitoring strategy with incident dark-field illumination imaging. Measurements were obtained before and 3 minutes after propofol induction. Total and perfused vessel densities, proportion of perfused vessels, microvascular flow index, blood vessel diameter (Øbv ), and systemic hemodynamics were analyzed. RESULTS: Continuous measurements were achieved in seven patients. Three minutes after propofol induction mean arterial pressure decreased (P = 0.028) and total and perfused vessel densities increased by 12% (P = 0.018) and 16% (P = 0.018), respectively. MFI was unaltered and mean Øbv increased but not significantly. CONCLUSIONS: Propofol induction induces a reduction in mean arterial pressure and a rise in sublingual microvascular perfusion. The observed effects of propofol on the sublingual microcirculation may be due to a decrease in microvascular resistance.

Intraoperative Incident Dark Field Imaging of the Human Peritoneal Microcirculation.

BACKGROUND/AIMS: This study describes the peritoneal microcirculation, compares quantitative parameters and angioarchitecture to the standard of sublingual microcirculatory assessment, and determines the practical feasibility of this method. METHODS: Incident dark field imaging was performed of the peritoneum and sublingually to determine angioarchitecture, total and perfused vessel density (TVD and PVD), the proportion of perfused vessels (PPV), the microvascular flow index (MFI) and image acquisition time. RESULTS: Peritoneal angioarchitecture was characterized by a quadrangular network of longitudinally oriented capillaries, often flanked by fat cells. Differences between peritoneal and sublingual microcirculation were observed with regard to TVD (peritoneum 12 mm/mm2 [95% CI 10-14] vs. sublingual 23 mm/mm2 [95% CI 21-25]; p < 0.0001), PVD (peritoneum 11 mm/mm2 [95% CI 9-13] vs. sublingual 23 mm/mm2 [95% CI 21-25]; p < 0.0001), PPV (peritoneum 88% [95% CI 79-97] vs. sublingual 99% [95% CI 99-100]; p = 0.014), and MFI (peritoneum 3 [IQR 2.3-3.0] vs. sublingual 3 [IQR 3.0-3.0]; p = 0.012). There was no difference in image acquisition time (peritoneum 2: 34 min [95% CI 1: 49-3: 19] vs. sublingual 2: 38 [95% CI 1: 37-3: 32]; p = 0.916). CONCLUSION: The peritoneal microcirculation was characterized by a low capillary density and a distinctive angioarchitecture. The possibility of peri-toneal microcirculatory assessment offers promise for the study of peritoneal (patho-)physiology and (monitoring or detection of) associated diseases.

Photobiomodulation therapy in the management of chronic oral graft-versus-host disease.

AIM: Patients treated with allogeneic hematopoietic stem cell transplantation (HSCT) may experience oral complications associated with chronic graft-versus-host disease (cGVHD). These complications may significantly affect quality of life, even many years post-HSCT. Current treatment options for oral cGVHD are limited and often include steroid or other immunomodulatory medications, which may not adequately control the oral condition. A non-immunosuppressive intervention for symptomatic relief in oral cGVHD would thus be a welcome addition to the treatment paradigm. MATERIALS AND METHODS: We report seven cases of oral cGVHD that were treated with photobiomodulation therapy (PBM), previously known as low-level laser therapy (LLLT). Patients underwent at least two PBM treatments per week in addition to local treatment with steroids, and if on systemic therapies, these were either unchanged or dosage was reduced during the period of PBM therapy. Follow-up data is presented for 4 weeks of treatment. RESULTS: Oral pain, sensitivity, and dry mouth improved in most patients. These findings suggest PBM therapy may represent an additional approach for management of oral cGVHD, and suggest that controlled studies should be conducted to confirm the efficacy and safety of PBM therapy in oral cGVHD and to determine optimal PBM therapy protocols.

Circulating microaggregates during cardiac surgery precedes postoperative stroke.

Postoperative stroke and encephalopathy are potentially serious complications associated with coronary artery bypass grafting. In this case report a 78-year-old male patient receiving routine elective cardiac surgery presented with microaggregations in the sublingual microcirculation while on cardiopulmonary bypass that was undetected by routine intraoperative anticoagulation assessment. Microaggregates identified using video microscopy on his sublingual microcirculation during the procedure preceded a stroke postoperatively. Postoperative cerebral and carotid artery examination with computed tomography scanning revealed a left watershed cerebral infarct with carotid stenosis. This report presents intraoperative microcirculation-based evidence suggesting that observations of microaggregations, otherwise undetected by conventional anticoagulation assessment techniques, could serve as an early warning in elderly patients at high risk for postoperative cerebrovascular events.

Sublingual microvascular perfusion is altered during normobaric and hyperbaric hyperoxia.

Hyperoxia and hyperbaric oxygen therapy can restore oxygen tensions in tissues distressed by ischemic injury and poor vascularization and is believed to also yield angiogenesis and regulate tissue perfusion. The aim of this study was to develop a model in which hyperoxia-driven microvascular changes could be quantified and to test the hypothesis that microcirculatory responses to both normobaric (NB) and hyperbaric (HB) hyperoxic maneuvers are reversible. Sublingual mucosa microcirculation vessel density, proportion of perfused vessels, vessel diameters, microvascular flow index, macrohemodynamic, and blood gas parameters were examined in male rabbits breathing sequential O2/air mixtures of 21%, 55%, 100%, and return to 21% during NB (1.0 bar) and HB (2.5 bar) conditions. The results indicate that NB hyperoxia (55% and 100%) produced significant decreases in microvascular density and vascular diameters (p<0.01 and p<0.05, respectively) accompanied by significant increases in systolic and mean arterial blood pressure (p<0.05, respectively) with no changes in blood flow indices when compared to NB normoxia. HB normoxia/hyperoxia resulted in significant decreases in microvascular density (p<0.05), a transient rise in systolic blood pressure at 55% (p<0.01), and no changes in blood vessel diameter and blood flow indices when compared to NB hyperoxia. All microcirculation parameters reverted back to normal values upon return to NB normoxia. We conclude that NB/HB hyperoxia-driven changes elicit reversible physiological control of sublingual mucosa blood perfusion in the presence of steady cardiovascular function and that the absence of microvascular vasoconstriction during HB conditions suggests a beneficial mechanism associated with maintaining peak tissue perfusion states.

Low level laser therapy/photobiomodulation in the management of side effects of chemoradiation therapy in head and neck cancer: part 1: mechanisms of action, dosimetric, and safety considerations.

PURPOSE: There is a large body of evidence supporting the efficacy of low level laser therapy (LLLT), more recently termed photobiomodulation (PBM), for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved, may expand the applications for PBM in the management of other complications associated with HNC treatment. This article (part 1) describes PBM mechanisms of action, dosimetry, and safety aspects and, in doing so, provides a basis for a companion paper (part 2) which describes the potential breadth of potential applications of PBM in the management of side-effects of (chemo)radiation therapy in patients being treated for HNC and proposes PBM parameters. METHODS: This study is a narrative non-systematic review. RESULTS: We review PBM mechanisms of action and dosimetric considerations. Virtually, all conditions modulated by PBM (e.g., ulceration, inflammation, lymphedema, pain, fibrosis, neurological and muscular injury) are thought to be involved in the pathogenesis of (chemo)radiation therapy-induced complications in patients treated for HNC. The impact of PBM on tumor behavior and tumor response to treatment has been insufficiently studied. In vitro studies assessing the effect of PBM on tumor cells report conflicting results, perhaps attributable to inconsistencies of PBM power and dose. Nonetheless, the biological bases for the broad clinical activities ascribed to PBM have also been noted to be similar to those activities and pathways associated with negative tumor behaviors and impeded response to treatment. While there are no anecdotal descriptions of poor tumor outcomes in patients treated with PBM, confirming its neutrality with respect to cancer responsiveness is a critical priority. CONCLUSION: Based on its therapeutic effects, PBM may have utility in a broad range of oral, oropharyngeal, facial, and neck complications of HNC treatment. Although evidence suggests that PBM using LLLT is safe in HNC patients, more research is imperative and vigilance remains warranted to detect any potential adverse effects of PBM on cancer treatment outcomes and survival.

Low-level laser therapy/photobiomodulation in the management of side effects of chemoradiation therapy in head and neck cancer: part 2: proposed applications and treatment protocols.

PURPOSE: There is a large body of evidence supporting the efficacy of low-level laser therapy (LLLT), more recently termed photobiomodulation (PBM) for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved and dosimetric parameters may lead to the management of a broader range of complications associated with HNC treatment. This could enhance patient adherence to cancer therapy, and improve quality of life and treatment outcomes. The mechanisms of action, dosimetric, and safety considerations for PBM have been reviewed in part 1. Part 2 discusses the head and neck treatment side effects for which PBM may prove to be effective. In addition, PBM parameters for each of these complications are suggested and future research directions are discussed. METHODS: Narrative review and presentation of PBM parameters are based on current evidence and expert opinion. RESULTS: PBM may have potential applications in the management of a broad range of side effects of (chemo)radiation therapy (CRT) in patients being treated for HNC. For OM management, optimal PBM parameters identified were as follows: wavelength, typically between 633 and 685 nm or 780-830 nm; energy density, laser or light-emitting diode (LED) output between 10 and 150 mW; dose, 2-3 J (J/cm(2)), and no more than 6 J/cm(2) on the tissue surface treated; treatment schedule, two to three times a week up to daily; emission type, pulsed (<100 Hz); and route of delivery, intraorally and/or transcutaneously. To facilitate further studies, we propose potentially effective PBM parameters for prophylactic and therapeutic use in supportive care for dermatitis, dysphagia, dry mouth, dysgeusia, trismus, necrosis, lymphedema, and voice/speech alterations. CONCLUSION: PBM may have a role in supportive care for a broad range of complications associated with the treatment of HNC with CRT. The suggested PBM irradiation and dosimetric parameters, which are potentially effective for these complications, are intended to provide guidance for well-designed future studies. It is imperative that such studies include elucidating the effects of PBM on oncology treatment outcomes.

Neonatal brain oxygenation during thoracoscopic correction of esophageal atresia.

BACKGROUND: Little is known about the effects of carbon dioxide (CO2) insufflation on cerebral oxygenation during thoracoscopy in neonates. Near-infrared spectroscopy can measure perioperative brain oxygenation [regional cerebral oxygen saturation (rScO2)]. AIMS: To evaluate the effects of CO2 insufflation on rScO2 during thoracoscopic esophageal atresia (EA) repair. METHODS: This is an observational study during thoracoscopic EA repair with 5 mmHg CO2 insufflation pressure. Mean arterial blood pressure (MABP), arterial oxygen saturation (SaO2), partial pressure of arterial carbon dioxide (paCO2), pH, and rScO2 were monitored in 15 neonates at seven time points: baseline (T0), after anesthesia induction (T1), after CO2-insufflation (T2), before CO2-exsufflation (T3), and postoperatively at 6 (T4), 12 (T5), and 24 h (T6). RESULTS: MABP remained stable. SaO2 decreased from T0 to T2 [97 ± 3-90 ± 6 % (p < 0.01)]. PaCO2 increased from T0 to T2 [41 ± 6-54 ± 15 mmHg (p < 0.01)]. pH decreased from T0 to T2 [7.33 ± 0.04-7.25 ± 0.11 (p < 0.05)]. All parameters recovered during the surgical course. Mean rScO2 was significantly higher at T1 compared to T2 [77 ± 10-73 ± 7 % (p < 0.05)]. Mean rScO2 levels never dropped below a safety threshold of 55 %. CONCLUSION: The impact of neonatal thoracoscopic repair of EA with insufflation of CO2 at 5 mmHg was studied. Intrathoracic CO2 insufflation caused a reversible decrease in SaO2 and pH and an increase in paCO2. The rScO2 was higher at anesthesia induction but remained stable and within normal limits during and after the CO2 pneumothorax, which suggest no hampering of cerebral oxygenation by the thoracoscopic intervention. Future studies will focus on the long-term effects of this surgery on the developing brain.

Pathophysiological consequences of TAT-HKII peptide administration are independent of impaired vascular function and ensuing ischemia.

RATIONALE: We have shown that partial dissociation of hexokinase II (HKII) from mitochondria in the intact heart using low-dose transactivating transcriptional factor (TAT)-HKII (200 nmol/L) prevents the cardioprotective effects of ischemic preconditioning, whereas high-dose TAT-HKII (10 µmol/L) administration results in rapid myocardial dysfunction, mitochondrial depolarization, and disintegration. In this issue of Circulation Research, Pasdois et al argue that the deleterious effects of TAT-HKII administration on cardiac function are likely because of vasoconstriction and ensuing ischemia. OBJECTIVE: To investigate whether altered vascular function and ensuing ischemia recapitulate the deleterious effects of TAT-HKII in intact myocardium. METHODS AND RESULTS: Using a variety of complementary techniques, including mitochondrial membrane potential (ΔΨm) imaging, high-resolution optical action potential mapping, analysis of lactate production, nicotinamide adenine dinucleotide epifluorescence, lactate dehydrogenase release, and electron microscopy, we provide direct evidence that refutes the notion that acute myocardial dysfunction by high-dose TAT-HKII peptide administration is a consequence of impaired vascular function. Moreover, we demonstrate that low-dose TAT-HKII treatment, which abrogates the protective effects of ischemic preconditioning, is not associated with ischemia or ischemic injury. CONCLUSIONS: Our findings challenge the notion that the effects of TAT-HKII are attributable to impaired vascular function and ensuing ischemia, thereby lending further credence to the role of mitochondria-bound HKII as a critical regulator of cardiac function, ischemia-reperfusion injury, and cardioprotection by ischemic preconditioning.

Vaginal microcirculation: Non-invasive anatomical examination of the micro-vessel architecture, tortuosity and capillary density.

AIM: To describe the vaginal microcirculatory architecture and capillary density parameters using sidestream dark-field imaging (SDFI), and determine feasibility and reliability of this method. METHODS: In nine healthy female volunteers SDFI measurements were performed at two different time points in the luteal phase of the menstrual cycle. Non-invasive tissue micro-angioarchitecture and vaginal capillary density measurements were assessed independently by two observers. Agreement was expressed with mean differences between the measurements of both observers and the limits of agreement. Inter- and intra-observer agreement was quantified with the intra-class correlation coefficient (ICC). RESULTS: Vaginal microcirculatory assessment with the SDFI device was easy in use, painless and well accepted by the participants. Morphologically, the vaginal microcirculation revealed an array of single hairpin-shaped capillary loops distributed homogeneously across an imaged tissue segment. The intra-observer assessment of the capillary density measurements (comparing two measurement time points of one observer) showed good agreement with an ICC ranging from 0.62 to 0.85. The inter-observer assessments of the capillary density measurements (comparing assessments of two observers at one time point) revealed very good agreement, with small differences between observers and an ICC of more than 0.9. CONCLUSIONS: This is the first report on both microcirculatory architecture and quantitative microcirculatory parameters of the vagina with the use of SDFI. Micro-vessels of the vagina show a recognizable pattern in our study population of young, healthy women. SDFI gives a reproducible assessment of the vaginal microcirculation offering the researcher a wide field of applications.

Absence of hydrogen sulfide-induced hypometabolism in pigs: a mechanistic explanation in relation to small nonhibernating mammals.

Artificially induced hypometabolism in nonhibernating mammals may have considerable clinical implications. Numerous studies in small rodent models have demonstrated that hydrogen sulfide (H2S) induces hypometabolism, supposedly as a result of histotoxic hypoxia. However, the induction of hypometabolism is absent in large animals following H2S administration. To determine the cause of this animal size-dependent discrepancy in H2S pharmacodynamics, the effects of sodium H2S (NaSH; 5 mg/kg/h, 4-hour intravenous administration) on systemic, pneumocardial, hematological, biochemical, microvascular (sublingual), and histological parameters were investigated in pigs. After 4 h, no differences were observed between the NaSH and control group with respect to systemic, pneumocardial, hematological, biochemical, and histological parameters. However, NaSH triggered significant hyperperfusion in the sublingual microcirculation, as evidenced by an increased blood vessel diameter (154 ± 16 and 85 ± 25% vs. baseline for NaSH and NaCl, respectively), total vessel density (139 ± 18 and 98 ± 13%, respectively), and perfused vessel density (139 ± 18 and 99 ± 13%, respectively). These phenomena are consistent with microvascular changes that occur during a panting response, an important heat loss mechanism (i.e., thermoregulatory effector) in pigs that is controlled by the thermoneutral zone (Ztn). On the basis of our findings and the literature, a mechanistic explanation is provided for the differential manifestation of hypometabolism between small and large animals. In large animals, H2S does not act via histotoxic hypoxia but likely triggers carotid bodies to transmit a hypoxic signal, which subsequently lowers the Ztn and activates heat loss mechanisms (e.g., panting) to align ATP consumption with ATP production through hypothermia. Since large animals have a small surface:size ratio, the cooling rate is too inefficient to accommodate hypothermia and subsequent hypometabolism. This is why large animals do not exhibit hypometabolism, despite the activation of thermoregulatory effectors. This is also a reason for the poor translatability of artificial hypometabolism to the clinical setting.

Effects of prolonged pneumoperitoneum on hepatic perfusion during laparoscopy.

OBJECTIVE: To assess the influence of prolonged pneumoperitoneum (PP) on liver function and perfusion in a clinically relevant porcine model of laparoscopic abdominal insufflation. BACKGROUND: PP during laparoscopic surgery produces increased intra-abdominal pressure, which potentially influences hepatic function and microcirculatory perfusion. METHODS: Six pigs (49.6 ± 5.8 kg) underwent laparoscopic intra-abdominal insufflation with 14 mm Hg CO2 gas for 6 hours, followed by a recovery period of 6 hours. Two animals were subjected to 25 mm Hg CO2 gas. Hemodynamic parameters were monitored, and damage parameters in the blood were measured to assess liver injury. Liver total blood flow and function were determined by the indocyanine green (ICG) clearance test. Intraoperative hepatic hemodynamics were measured by simultaneous reflectance spectrophotometry (venous oxygen saturation StO2 and relative tissue hemoglobin concentration rHb) and laser Doppler flowmetry (blood flow and flow velocity). Postmortem liver samples were collected for histological evaluation. RESULTS: A decrease in microvascular perfusion was observed during PP. After 6 hours of PP, ICG clearance increased (P < 0.001), indicating a compensatory improvement of overall liver blood flow resulting in concomitantly improved microcirculatory perfusion (P = 0.024). Minimal parenchymal damage (aspartate aminotransferase) of the liver was seen after 6 hours of PP (P = 0.006), which seemed related to PP pressure. Minor histological damage was observed. CONCLUSIONS: The liver sustains no additional damage due to prolonged PP during laparoscopic surgery. Our findings suggest that prolonged PP does not hamper liver function or cause liver damage after extended laparoscopic procedures.

Laser speckle contrast imaging for assessment of liver microcirculation.

OBJECTIVE: Laser speckle contrast imaging (LSCI) is a novel technique for microcirculation imaging not previously used in the liver. The aim of the present experimental study was to evaluate the use of LSCI for assessing liver microcirculation. MATERIALS AND METHODS: In six male Wistar rats, the median liver lobe was exposed through a midline laparotomy. Liver blood perfusion was measured simultaneously with LSCI and sidestream dark-field (SDF) imaging at baseline and during sequential temporary occlusions of the portal vein, hepatic artery, and total blood inflow occlusion. Both the inter-individual variability associated with perfusion sampling area and comparisons in perfusion measurements between both imaging techniques were investigated and validated for the application of LSCI in the liver. RESULTS: Occlusion of the hepatic artery, portal vein, and total inflow occlusion resulted in a significant decrease in LSCI signal to 74.7±6.4%, 15.0±2.3%, and 10.4±0.5% respectively (p<0.005 vs. baseline). The LSCI perfusion units correlated with sinusoidal blood flow velocity as measured with SDF imaging (Pearson's r=0.94, p<0.001). In a 10 mm diameter region of interest, as measured with LSCI, baseline inter-individual variability measured by the coefficient of variability was 13%. CONCLUSION: Alterations in LSCI signal during sequential inflow occlusions were in accordance with previously published results on hepatic hemodynamics in the rat and correlated well with our SDF imaging-derived sinusoidal blood flow velocity measurements. We found that LSCI was able to produce reproducible real-time blood perfusion measurements of hepatic microcirculation. Compared to established techniques for liver blood perfusion measurements LSCI holds the advantages of non-contact measurements over large surfaces with a high speed of data acquisition.

Transfusion of banked red blood cells and the effects on hemorrheology and microvascular hemodynamics in anemic hematology outpatients.

BACKGROUND: The aim of this study was to investigate the effects of red blood cell (RBC) transfusion on the hemorrheologic properties and microcirculatory hemodynamics in anemic hematology outpatients receiving 2 to 4 RBC units of either "fresh" (leukoreduced storage for less than 1 week) or "aged" (leukoreduced storage for 3-4 weeks) RBCs. STUDY DESIGN AND METHODS: Measurements were performed before and 30 minutes after RBC transfusion in hematology outpatients. Leukoreduced RBC suspensions were stored in saline-adenine-glucose-mannitol (SAGM) additive solution. Whole blood viscosity was measured using Couette low-shear viscometry, RBC deformability and aggregability were measured using laser-assisted optical rotational cell analysis, and microcirculatory density and perfusion were assessed using sidestream dark field imaging. RESULTS: One group of patients (n = 10) received a median (interquartile range) of 3 (2-3) RBC bags that were stored for 7 (5-7) days (fresh) and the other group of patients (n = 10) received 3 (3-3) RBC bags that were stored for 23 (22-28) days (aged). After transfusion of fresh versus aged RBCs, hematocrit increased to 32 ± 3% versus 31 ± 2% (p < 0.363), whole blood viscosity increased to 4.2 ± 0.4 Pa/sec versus 4.2 ± 0.6 Pa/sec (p < 0.912), RBC deformability index remained unaffected, RBC aggregability index increased to 55 ± 10 versus 55 ± 13 (p = 0.967), microcirculatory flow remained unaffected, and microcirculatory density increased to 19.3 ± 2.5 mm/mm(2) versus 18.7 ± 1.9 mm/mm(2) (p = 0.595), respectively. CONCLUSION: Storing leukoreduced SAGM-suspended RBCs for 3 to 4 weeks did not affect their ability to improve hemorrheologic properties and microcirculatory hemodynamics in our small group of anemic hematology outpatients. Larger studies are needed to confirm this finding.

Carbon dioxide gas pneumoperitoneum induces minimal microcirculatory changes in neonates during laparoscopic pyloromyotomy.

BACKGROUND: Little is known about the direct effect of pneumoperitoneum (PP) on microcirculation and its influence on the quality of tissue perfusion. This study aimed to investigate the intraoperative effects of carbon dioxide (CO2) gas PP on microcirculation density and perfusion in neonates receiving laparoscopic surgery for hypertrophic pyloric stenosis. METHODS: In a single-center observational study, the oral microcirculation in 12 neonates receiving laparoscopic pyloromyotomy was investigated. Intraoperative hemodynamic parameters, intermittent buccal mucosa capillary density measurements (pre- and postoperative), and continuous intraoperative sublingual microcirculation measurements (i.e., vessels with a diameter <25 µm) of total vessel density, perfused vessel density, proportion of perfused blood vessels, blood vessel diameters (BVd), and microvascular flow index were obtained before (at baseline), during, and after PP insufflation for all patients using sidestream dark-field imaging for the duration of the complete surgical procedure. RESULTS: With the exception of a significantly elevated end-tidal CO2 (34 ± 4-40 ± 8 mmHg; p < 0.05 vs before [baseline], one-way analysis of variance [ANOVA]) during intraoperative insufflation, no significant differences were found between time points for the intraoperative hemodynamic parameters. Pre- and postoperative buccal capillary density showed no significant changes in mucosal perfusion. Analysis of continuous intraoperative sublingual microcirculation parameters exhibited a statistically significant increase in BVd during insufflation (8.8 ± 2.4-9.3 ± 2.5 µm; p < 0.05, one-way ANOVA) and a significant decrease after exsufflation (8.2 ± 2.3 µm; p < 0.01 vs during insufflation and p < 0.05 vs baseline, one-way ANOVA, respectively). No other significant differences were found between time points for the remaining microcirculatory parameters. CONCLUSION: The installation of CO2 gas PP during laparoscopic pyloromyotomy procedures regulates microcirculatory perfusion by inducing changes in microvascular diameters but does not alter microcirculation density in neonates.

Facial esthetics and subjective impairment assessed after maxillomandibular advancement surgery for patients with obstructive sleep apnea.

OBJECTIVE: To assess facial esthetics and quality of life (QoL) as measure of success or failure after maxillomandibular advancement (MMA) surgery for obstructive sleep apnea (OSA). METHODS: Visual analog scales (VAS) on facial esthetics and QoL survey, including EQ-5D3L, Epworth Sleepiness Scale (ESS), and Functional Outcome of Sleep Questionnaire (FOSQ) were collected. Outcomes were analyzed for surgical-success/failure after MMA. RESULTS: Forty-one patients returned completed surveys (response: 66%). Mean VAS on facial esthetics was 57 ± 22 mm preoperative and 51 ± 24 mm postoperative (p = 0.217). When MMA was considered a surgical-failure, VAS was significantly more negative (40 ± 22 mm; p = 0.026). EQ-5D-3L showed an overall mean score of 73.2 ± 15.7, ESS was 6.3 ± 5.4, and FOSQ was 16.0 ± 3.3. CONCLUSION: No significant alteration of facial esthetics were reported after MMA; however, lower QoL was associated with surgical-failure; whereas, in surgical-success, QoL were higher.

Red blood cell transfusions and tissue oxygenation in anemic hematology outpatients.

BACKGROUND: There is little clinical evidence that red blood cell (RBC) transfusions improve oxygen availability at the microcirculatory level. We tested the hypotheses that anemia in chronically anemic patients with relatively healthy microcirculation would be associated with low tissue hemoglobin (Hb) and tissue oxygenation levels and that these conditions would be improved after RBC transfusions. STUDY DESIGN AND METHODS: Near-infrared spectroscopy (NIRS) was used to determine tissue oxygen saturation (StO(2)) and tissue Hb index (THI; an index of the amount of Hb in the NIRS measurement volume) in the thenar eminence and sublingual tissue before and 30 minutes after RBC transfusions in 20 chronically anemic hematology outpatients. Data are presented as median (25%-75%). RESULTS: The patients received three (two to three) bags of RBCs in saline-adenine-glucose-mannitol with an age of 21 (7-21) days, which was infused intravenously at the rate of 0.7 bag/hr. RBC transfusions significantly increased hematocrit level from 26% (24%-28%) to 32% (30%-34%; p < 0.0001), Hb level from 8.2 (7.6-8.9) g/dL to 11.0 (9.9-11.8) g/dL (p < 0.0001), whole blood viscosity from 3.4 (3.1-3.5) mPa/sec to 4.2 (4.0-4.5) mPa/sec (p < 0.0001), thenar StO(2) from 81% (80%-84%) to 86% (81%-89%; p = 0.002), thenar THI from 11.2 (9.3-13.3) AU to 13.7 (9.7-15.3) AU (p = 0.024), sublingual StO(2) from 86% (81%-89%) to 91% (86%-92%; p < 0.0001), and sublingual THI from 15.2 (13.0-17.4) AU to 17.2 (13.5-19.7) AU (p = 0.040). CONCLUSION: Although anemia in chronically anemic hematology outpatients was not associated with low StO(2) and THI levels, RBC transfusions were successful in improving these variables.