Relative Amount Of Hemoglobin Research Articles

Evaluation of peri-implant perfusion in patients who underwent avascular augmentation or microvascular reconstruction using laser Doppler flowmetry and tissue spectrophotometry: a prospective comparative clinical study

ObjectivesThe aim of this study was to evaluate the peri-implant perfusion, such as oxygen saturation, the relative amount of hemoglobin, and blood flow, in implants placed in pristine bone and avascular and microvascular grafts using a non-invasive measurement method.Materials and methodsA total of 58 patients with 241 implants were included. Among them, 106 implants were based in native bone (group I), 75 implants were inserted into avascular bone grafts (group II), and 60 implants were placed in microvascular bone grafts (group III). Gingival perfusion was measured using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS). Implants with signs of gingival inflammation were excluded to analyze healthy implant perfusion in different bony envelopes.ResultsThe mean values for oxygen saturation, relative hemoglobin levels, and blood flow did not differ significantly between the groups (p = 0.404, p = 0.081, and p = 0.291, respectively). There was no significant difference in perfusion between implants that were surrounded by mucosa and implants based within cutaneous transplants (p = 0.456; p = 0.628, and p = 0.091, respectively).ConclusionNo differences in perfusion were found between implants inserted into native bone and implants involving bone or soft tissue augmentation. However, implants based in avascular and microvascular transplants showed higher rates of peri-implant inflammation.Clinical relevancePeri-implant perfusion seems to be comparable for all implants after they heal, irrespective of their bony surroundings. Although perfusion does not differ significantly, other factors may make implants in avascular and microvascular transplants vulnerable to peri-implant inflammation.

Comparing the Time-Dependent Evolution of Microcirculation in Gracilis vs. ALT Flaps Using Laser-Doppler Flowmetry and Tissue-Spectrometry.

Postoperative free flap monitoring is considered a key component of care after microsurgical reconstruction. To achieve successful flap salvage after surgical revision, early recognition of vascular compromise is required. The aim of this study was to assess and compare the time-dependent evolution of microcirculation in gracilis muscle (GM) and anterolateral thigh (ALT) flaps. This study included continuous measurements of blood flow (flow), hemoglobin oxygenation (SO2) and the relative amount of hemoglobin (rHb) using laser-doppler flowmetry and tissue-spectrometry (O2C, LEA Medizintechnik, Gießen, Germany) over a time-period of 72 h. Microcirculation was assessed in a total of 66 viable free flaps (GM n = 40; ALT n = 26). A statistically significant positive correlation between time post-anastomosis and microvascular flow was found for both GM and ALT flaps with rs = 0.384 (p < 0.001) and rs = 0.178 (p = 0.015), respectively. No significant positive or negative correlations between time post-anastomosis and SO2 were found for both GM and ALT flaps with rs = 0.052 (p = 0.387) and rs = −0.018 (p = 0.805), respectively. Overall, a significant negative correlation between time post-anastomosis and rHb was found for GM flaps with rs = −0.140 (p = 0.019). For ALT flaps, no significant positive or negative correlation was found with rs = −0.011 (p = 0.887). Microcirculation differs in different flap entities, and surgeons should be aware of these differences in order to correctly evaluate and classify the values of flow, SO2 and rHb obtained when using the O2C device for postoperative monitoring.

The 72-Hour Microcirculation Dynamics in Viable Free Flap Reconstructions.

The risk for vascular complications is the highest within the first 24 hours after free flap transfer. Clinical signs of critical perfusion are often recognized with time delay, impeding flap salvage. To detect failing flaps as soon as possible and to prevent persisting microvascular impairments, knowledge of physiological perfusion dynamics in free flaps is needed. Aim of this study was to investigate the physiological perfusion dynamics of viable free flaps using the Oxygen to See (O2C) device for continuous monitoring. Microcirculation was continuously monitored in 85 viable free flaps over a period of up to 72 hours following microvascular anastomosis using tissue spectrophotometry and laser Doppler flowmetry (O2C, LEA Medizintechnik, Gießen, Germany). The parameters investigated included capillary-venous blood flow (flow), oxygen saturation (SO2), and relative amount of hemoglobin (rHB). Microcirculatory blood flow increased significantly overall, especially within the first 18 hours after microsurgical anastomosis, after which peak formation was occurred. Mean values of SO2 showed a decreasing trend and the steepest decrease of SO2 (slope: 1.0) occurred during the steepest increase of flow between 3 and 6 hours (slope: 4.7) postanastomosis. The rHB values remained fairly constant throughout the study period. Hyperemia after free flap transfer accounts for a significant increase of microvascular flow. Tissue oxygenation is reduced, likely due to an increase of oxygen consumption after anastomosis. A better understanding of physiological perfusion dynamics in free flaps can aid surgeons in recognizing compromised vasculature earlier and improve free flap salvage.

Free Gingival Graft and Collagen Matrix Revascularization in an Enoral Open Wound Situation

Vestibuloplasty with free gingival grafting is a frequently performed surgical procedure to generate sufficient keratinized mucosa (KM) around dental implants. Avascular porcine collagen matrices (CM) have been proclaimed to be sufficient substitutes as alternatives to free gingival grafts (FGGs). However, the process of graft integration and vascularization is still incompletely understood. In 18 patients a vestibuloplasty in the lower edentulous jaw situation was performed during implant exposure, either with FGGs from the palate or a porcine CM (mucoderm). Tissue perfusion of the soft tissue grafts was measured using laser-doppler-spectrophotometer intraoperatively and on postoperative days 2, 5, 10, 30 and between days 60 and 90. With graft perfusion expressed by oxygen saturation [SO2%], the relative amount of hemoglobin [rHb], blood flow, and velocity [AU] was detected and compared between groups and the surrounding mucosa. Healing was uneventful in both groups, with mature KM around dental implants after healing. Blood flow and velocity significantly increased until postoperative day 10, comparable to perfusion values of the surrounded mucosa. Intergroup comparisons revelated no significant differences concerning the flow between CM and FGGs. Oxygen saturation also significantly increased within the first 5 postoperative days in both groups. Hemoglobin content did not show any differences during the investigated period. The perfusion mainly progresses within the first postoperative week with only minimal further detectable alterations until the final investigation, comparable in both groups. Although integration of FGGs (revascularized) and the CM (new tissue formation) is biologically different, both transplants show comparable perfusion patterns, leading to sufficient KM.

Multimodal Device and Computer Algorithm-Based Monitoring of Pancreatic Microcirculation Profiles In Vivo.

Pancreatic microcirculation has an essential role in orchestrating pancreatic homeostasis. Inherent complexity and technological limitation lead to interobserver variability and 1-sided microcirculatory data. Here, we introduce a multimodal device and computer algorithm-based platform for monitoring and visualizing integrated pancreatic microcirculation profiles. After anesthetizing and exposing pancreas tissue of BALB/c mice, probes of Oxygen to See, Microx TX3, and MoorVMS-LDF2 were positioned at pancreas in situ to capture the pancreatic microcirculatory oxygen (hemoglobin oxygen saturation, relative amount of hemoglobin, and partial oxygen pressure) and microhemodynamic data (microvascular blood perfusion and velocity). To assess and visualize pancreatic microcirculation profiles, raw data of pancreatic microcirculation profiles were processed and transformed using interquartile range and min-max normalization by Python and Apache ECharts. The multimodal device-based platform was established and 3-dimensional microcirculatory modules were constructed. Raw data sets of pancreatic microcirculatory oxygen and microhemodynamic were collected. The outlier of data set was adjusted to the boundary value and raw data set was preprocessed. Normalized pancreatic microcirculation profiles were integrated into the 3-dimensional histogram and scatter modules, respectively. The 3-dimensional modules of pancreatic microcirculation profiles were then generated. We established a multimodal device and computer algorithm-based monitoring platform for visualizing integrated pancreatic microcirculation profiles.

Determination of baseline alveolar mucosa perfusion parameters using laser Doppler flowmetry and tissue spectrophotometry in healthy adults

Objectives: To determine the baseline perfusion parameters of the alveolar mucosa using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS) in healthy adults.Material and methods: Forty-two healthy adult subjects of either sex were tested. The perfusion of the alveolar mucosa was evaluated using a laser Doppler flowmetry and tissue spectrophotometry using O2C ‘oxygen to see’ device. The measurements encompassed the maxillary and mandibular mucosa at 20 different points.Results: The O2C device is a reliable method for noninvasive measurement of different perfusion parameters of the oral mucosa. The hemoglobin saturation values (So2 in %), as well as relative amount of hemoglobin in arbitrary units (AU) of the maxillary mucosa demonstrated lower values of that in the mandible. The flow value (AU) exhibited a significant difference in the posterior molar region only, while the velocity value (AU) showed a significant difference across all points except for the anterior region.Conclusion: the present study provides a set of brand-new perfusion parameters of the microcirculation of the alveolar mucosa using LDF-TS. The study suggests a variation of the perfusion parameters between the maxilla and the mandible. Differences in the anatomy of the blood supply, the thickness of the mucosa and the cortical bone, may be attributed to this variation. Further studies using different probes and a combination of ultrasonic measurements and SDF imaging will aid in giving a better overview of the perfusion in the oral mucosa.

Collagen Matrix Vascularization in a Peri-Implant Vestibuloplasty Situation Proceeds Within the First Postoperative Week

Vestibuloplasty is a frequently performed surgical procedure to create or increase soft tissue mucosal sealing around dental restorations. Collagen matrices have exhibited comparable clinical results as free gingival grafts in the context of intraoral tissue augmentation. However, the process of matrix vascularization, the basic requirement for local healing, is incompletely understood. Therefore, this study investigated collagen matrix perfusion in a clinical intraoral setting. In a prospective cohort study, vestibuloplasty was performed during implant exposure using prefabricated collagen matrices. Matric perfusion was determined intraoperatively and at days 2, 5, 7, 14, 30, and 90 using a laser Doppler spectrophotometer measuring oxygen saturation, relative amount of hemoglobin, blood flow, and blood velocity as primary outcome variables. These parameters were compared with perfusion of the oral mucosa surrounding the matrices. Statistical analysis was performed by applying variance and regression models. In 10 patients (average age, 60.9yr), vestibuloplasty was performed exclusively in the anterior mandible. Blood flow and tissue oxygen saturation in the augmented zones markedly increased until postoperative day 5 and approximated perfusion values of the adjacent mucosa at the following 2 time points. Likewise, matrix oxygen saturation markedly increased until day 7 and subsequently converged to perfusion parameters of the surrounding mucosa at the following time points. Flow signals in incorporated collagen matrices occurred on day 2 after vestibuloplasty and further increased until days 5 to 7. Therefore, matrix perfusion mainly occurs within the first postoperative week, converging to perfusion levels of the surrounding mucosa with minimal alterations during the following course.

A Quantitative Analysis of Microcirculation in Skin Defects Covered with Topical Wound Dressings or a Newly Developed Collagen Matrix.

Innovative skin substitutes and temporary wound dressings are frequently used in the treatment of superficial and partial-thickness wounds. The aim of this study was to compare 2 commonly used temporary skin dressings with a newly developed collagen matrix to determine changes in microcirculation as measured by blood flow, hemoglobin oxygenation, and relative hemoglobin values during healing of partial-thickness skin defects. This animal study involved 28 adult male Lewis rats. On the back of each rat, 2 standardized partial-thickness skin defects were generated through a skin dermatome (n = 56). Then, wounds were treated with polylactide-based copolymer skin substitute (Suprathel, PolyMedics, Denkendorf, Germany; n = 14), biosynthetic skin dressing (Biobrane, Smith & Nephew, Hamburg, Germany; n = 14), or Collagen Cell Carrier (CCC; Naturin Viscofan, Weinheim, Germany; n = 14). The remaining control wounds were left untreated (n = 14). Perfusion dynamics were assessed every 10 days for 80 days with the O2C device (LEA Medizintechnik, Gieβen, Germany) to determine blood flow, hemoglobin oxygenation, and relative amount of hemoglobin. Blood flow was increased in all wounds for at least 30 days after wound generation. The relative amounts of hemoglobin were increased in superficial layers (2 mm) for 10 to 20 days. Hemoglobin oxygenation in the superficial layers decreased in the polylactide-based copolymer skin substitute and biosynthetic skin dressing-treated groups and initially increased in the untreated wounds and CCC groups on day 10; these values also decreased. The presented results demonstrate the complex changes in microcirculation in the course of healing partial-thickness wounds with different wound dressings and contribute to a better understanding of these wounds. However, based on the results of the study, a clear recommendation for a specific substitute is not yet possible.

Determining the appropriate number and duration of leech therapy in congested tissues using tissue spectrophotometry and laser Doppler flowmetry.

A universal protocol determining the number of leeches and their application time does not exist. The aim of this study, therefore, is to quantify perfusion dynamics in venous congested tissues after leech application to get more detailed information about changes due to leech-induced skin microcirculation and to evaluate the usability of the Oxygen to See (O2C) device in terms of determining the appropriate number of leeches and the duration of therapy. Twelve patients with the need for leech therapy participated in the study. Perfusion dynamics of the congested tissue was assessed using the O2C device, which determines blood flow (BF), the relative amount of hemoglobin (rHB), and the oxygen saturation (SO2). Measurements were carried out before leech application and on various intervals like 10 minutes, one hour, and three hours after leech application. The leech application effectuated after 10 minutes a nonsignificant perfusion improvement, which further increased after one hour with a significant reduction of the relative amount of hemoglobin and a significant increase of blood flow and oxygen saturation (BF= +56.7%; rHB= -25.5%; SO2= +53.7%). After three hours, the values returned to the levels before leech administration. In two cases, in which further administration of leeches within the measurement period was necessary, no substantial perfusion changes were obtained. The results of this study forms a more precise pattern of microcirculatory changes of leech therapy in congested tissues. According to our measurements a venous drainage improvement can be expected in congested tissue one hour after leech administration. The O2C seems to be a useful method to determine the appropriate number and duration of leech therapy.

Analysis of the microcirculation after soft tissue reconstruction of the outer ear with burns in patients with severe burn injuries

Reconstruction of soft tissue defects of the ear with burns remains one of the most difficult tasks for the reconstructive surgeon. Although numerous reconstructive options are available, the results are often unpredictable and worse than expected. Besides full and split skin grafting, local random pattern flaps and pedicled flaps are frequently utilized to cover soft tissue defects of the outer auricle. Because of the difficulty and unpredictable nature of outer ear reconstruction after burn injury, a case-control study was conducted to determine the best reconstructive approach. The microcirculatory properties of different types of soft tissue reconstruction of the outer ear with burns in six severely burned Caucasian patients (three men and three women; mean age, 46years (range, 22-70)) were compared to those in the healthy tissue of the outer ear using the O2C device (Oxygen to See; LEA Medizintechnik, Gießen, Germany). The results of this study revealed that the investigated microcirculation parameters such as the median values of blood flow (control group: 126 AU), relative amount of hemoglobin (control group: 59.5 AU), and tissue oxygen saturation (control group: 73%) are most similar to those of normal ear tissue when pedicled flaps based on the superficial temporal artery were used. These findings suggest that this type of reconstruction is superior for soft tissue reconstruction of the outer ear with burns in contrast to random pattern flaps and full skin grafts regarding the microcirculatory aspects. These findings may improve the knowledge on soft tissue viability and facilitate the exceptional and delicate process of planning the reconstruction of the auricle with burns.

Utilization of laser Doppler flowmetry and tissue spectrophotometry for burn depth assessment using a miniature swine model.

Currently, the diagnosis of burn depth is primarily based on a visual assessment and can be dependent on the surgeons' experience. The goal of this study was to determine the ability of laser Doppler flowmeter combined with a tissue spectrophotometer to discriminate burn depth in a miniature swine burn model. Burn injuries of varying depth, including superficial-partial, deep-partial, and full thickness, were created in seven Göttingen minipigs using an aluminium bar (100 °C), which was applied to the abdominal skin for periods of 1, 3, 6, 12, 30, and 60 seconds with gravity alone. The depth of injury was evaluated histologically using hematoxylin and eosin staining. All burns were assessed 3 hours after injury using a device that combines a laser light and a white light to determine blood flow, hemoglobin oxygenation, and relative amount of hemoglobin. The blood flow (41 vs. 124 arbitrary units [AU]) and relative amount of hemoglobin (32 vs. 52 AU) were significantly lower in full thickness compared with superficial-partial thickness burns. However, no significant differences in hemoglobin oxygenation were observed between these depths of burns (61 vs. 60%). These results show the ability of laser Doppler flowmeter and tissue spectrophotometer in combination to discriminate between various depths of injury in the minipig model, suggesting that this device may offer a valuable tool for burn depth assessment influencing burn management.

Use of micro-lightguide spectrophotometry for evaluation of microcirculation in the small and large intestines of horses without gastrointestinal disease.

To evaluate the use of a micro-lightguide tissue spectrophotometer for measurement of tissue oxygenation and blood flow in the small and large intestines of horses under anesthesia. 13 adult horses without gastrointestinal disease. Horses were anesthetized and placed in dorsal recumbency. Ventral midline laparotomy was performed. Intestinal segments were exteriorized to obtain measurements. Spectrophotometric measurements of tissue oxygenation and regional blood flow of the jejunum and pelvic flexure were obtained under various conditions that were considered to have a potential effect on measurement accuracy. In addition, arterial oxygen saturation at the measuring sites was determined by use of pulse oximetry. 12,791 single measurements of oxygen saturation, relative amount of hemoglobin, and blood flow were obtained. Errors occurred in 381 of 12,791 (2.98%) measurements. Most measurement errors occurred when surgical lights were directed at the measuring site; covering the probe with the surgeon's hand did not eliminate this error source. No measurement errors were observed when the probe was positioned on the intestinal wall with room light, at the mesenteric side, or between the mesenteric and antimesenteric side. Values for blood flow had higher variability, and this was most likely caused by motion artifacts of the intestines. The micro-lightguide spectrophotometry system was easy to use on the small and large intestines of horses and provided rapid evaluation of the microcirculation. Results indicated that measurements should be performed with room light only and intestinal motion should be minimized.

Assessment of microcirculatory changes of cold contact injuries in a swine model using laser Doppler flowmetry and tissue spectrophotometry

BackgroundUntil now, the exact pathophysiology of frostbite injuries is poorly understood. The aim of the study is to evaluate the perfusion changes of frostbite injuries to get a better understanding of the exact mechanism underlying the resulting tissue damage. Particular attention has been given to the differentiation of changes between the various injury depths. MethodsCold contact injury ranging from superficial, superficial-partial, deep-partial to full thickness were generated using seven goettingen minipigs. The perfusion dynamics were assessed before and 3h after the injuries were inflicted using the O2C-device, which combines a laser light, to determine blood flow, and white light to determine hemoglobin oxygenation and relative amount of hemoglobin. A total of 42 cold contact injuries were inflicted and 84 measurements were carried out. ResultsIn superficial and superficial partial injuries there was an increase in the blood flow (mean, 20±2.4%, 15±5.1%, respectively) and in the relative amount of hemoglobin (mean, 29±9.1%, 28±7.2%, respectively), whereas the hemoglobin oxygenation did not alter (mean, −0.15±2.4%, −0.8±3.1%, respectively). In deep partial injuries there was a decrease in the blood flow (mean range, −4±2.1 to −17±4.7%) and an increase in the relative amount of hemoglobin (mean range, 79±17.2 to 93±17.7%), whereas the hemoglobin oxygenation did not alter (mean range, −0.7±3.1 to −2.9±3.3%). In full thickness injuries there was a drop in the blood flow (mean range, −24±7.6 to −27±11.8%) and in the hemoglobin oxygenation (mean range, −16±3.5 to −19±2.5%) and an increase in the relative amount of hemoglobin (mean range, +126±19.8 to 145±10.9%). ConclusionThe results of this study form a more precise pattern of cold contact injury perfusion changes, which can be a valuable tool to assess the degree of cold contact injury and furthermore the efficacy of novel diagnostic aids, therapeutics and treatment modalities.

Evaluation of a non‐invasive monitoring method for free flap breast reconstruction using laser doppler flowmetrie and tissue spectrophotometry

Despite advances in the monitoring of free flaps, there is still a demand for new technology to detect ischemic complications at an early stage. The aim of the present study was to evaluate the reliability of the O2C-device in terms of detecting flap failure in commonly used perforator flaps for breast reconstruction. A total of 34 patients undergoing breast reconstruction were involved in this study. The perfusion dynamics of 23 deep inferior epigastric perforator flaps and 11 superior gluteal arterial perforator flaps were assessed using the O2C-device, which combines a laser light, to determine blood flow (flow), velocity, and white light to determine hemoglobin oxygenation (SO(2)) and relative amount of hemoglobin (rHB). Measurements were carried out intra-operatively after clamping and declamping the perforator vessels. In the post-operative period measurements were carried out every hour for the first 48 hours and from 3rd to 7th for every 2 hours. These dates were compared to findings of clinical assessment. Several intra-operative measurements, during the clamping and declamping the different perforator vessels, revealed a high correlation for all parameters: Flow (r = 0.89, P < 0. 05), Velo (r = 0.92, P < 0. 05), SO2 (r =0.84, P <0. 05), and rHB (r =0.83 P < 0.05). Vessel occlusion was detected in five cases, of which three were due to arterial thrombosis and two further cases were due to venous occlusion. Of the five cases, one flap loss caused by venous occlusion was noted. The O2C-device seems to be a reliable, objective, and non-invasive device for the monitoring of free flaps. Thus, it may improve flap survival rates by detecting vascular compromise at an early stage.