Laser Doppler Flowmetry Values Research Articles

Ice cooling challenge as a means to probe skin microvascular function

Skin microvasculature provides a window to study both systemic and local physiology. In vascular medicine, various challengers such reactive hyperemia, hypoxia or hyperoxia, and heat, have been used to study function and search for potential clinical biomarkers. A positive relationship between increased skin temperature and skin perfusion has been suggested, but skin cooling as a challenger has not been well explored. In the present study, the adaptive cardiovascular and hemodynamic impacts of single hand cooling were examined in a group of ten healthy women, 27.3±7.9 years old, of normal body mass index and ankle-brachial index, normotensive, non-smoking, and free from any medication and supplements. The study followed all principles of good clinical practice and ethics commission approval. After complete stabilization, a participant’s palm, randomly chosen, was placed in contact with a frozen surface covered by a plasticized cotton cloth. Blood perfusion was measured using a laser Doppler flowmetry (LDF) instrument, and temperature were continuously registered in both hands, before, during, and after (early and late recovery) the ice cooling challenge. Nominal values for blood perfusion and temperature were considered, as well as their wavelet transform (WT) components, translating endothelial [0.0095; 0.021] Hz, autonomic [0.021; 0.052] Hz, myogenic [0.052; 0.015] Hz, respiratory [0.15; 0.6] Hz, and cardiac [0.6; 2] Hz activities. No significant differences were observed between limbs regarding nominal LDF values for each experimental phase. Nonetheless, significant differences were observed for nominal temperature signals between limbs during the challenge (Wilcoxon’s signed rank test; p=0.047), and for early (p=0.028) and late (p=0.028) recovery phases. Significant differences were observed for ipsi- and contralateral LDF signals (Friedmann’s test, p<0.001, and p=0.012, respectively), and also for ipsi- and contralateral temperature signals (Friedmann’s test, p<0.001, and p=0.004, respectively). These contralateral responses have been previously described with other challengers applied only in the ipsilateral limb, whilst it is known that local cooling stimulates cutaneous thermoreceptors, sympathetic nerve activity and cutaneous vascular resistance. However, our findings also show that temperature may be more sensitive than LDF for studying the ice cooling challenge, and that the WT analysis approach can provide potential physiological interpretations. Nonetheless, a strong positive correlation (Spearman’s rs = 0.820, p<0.001) was observed between temperature and LDF signals overall for both limbs. In conclusion, this preliminary study suggests that this cooling challenger is effective to elicit vascular physiological changes in both limbs, indicating a putative centrally-mediated adaptive process that might be quantified by changes in cardiac and respiratory activities, as shown from WT analysis. Additionally, temperature signals and the use of WT analysis seem to provide more sensitive and explanatory insights than the use of LDF signals and nominal values alone. Suported by COFAC/ALIES. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Light physical activity improves lower limb perfusion asymmetries in older sedentary adults — an exploratory study

Perfusion asymmetries between lower limbs are common even in healthy young individuals, although their physiological significance is unknown. Even in the absence of vascular disease, ageing is among the determinants that seem to accentuate those differences. While it is known that physical activity affects vascular hemodynamics, its specific impact on perfusion asymmetries in healthy elderly individuals is still unclear. This study aimed to identify vascular asymmetries and their variations after a regular program of light exercise in older individuals with age-related comorbidities in the absence of peripheral vascular disease (PVD). Ten participants, mean age 62.4 ± 5.6 years old, were selected following specific criteria. Participants were mostly sedentary, combining one or more common morbidities for this age group — in particular hypertension, overweight and / or diabetes (T2D). Exclusion criteria were an abnormal Ankle-Brachial Index assessed in a standing position at rest and evidence of compromised mobility. All procedures respected the principles of good clinical practice, being previously submitted and approved by the institutional Ethical Commission. Lower limb perfusion was assessed in both feet (anteromedial region) at two time points — day zero (D0) and thirty days later (D30) — using two optical-based technologies — Laser Doppler Flowmetry (LDF) and Polarized Spectroscopy (PSp). These two technologies measure at different depths, with LDF providing deeper tissue readings. During this evaluation period, participants underwent a daily structured program of light exercises based on the FITT principles (F, frequency; I, intensity; T, time and T, type of activity/activity performance) centred in the lower limb perfusion. The group revealed significant asymmetries at D0, where the right foot consistently showed higher values with both technologies correlating positively. At D30, LDF values increased by 57.5% in both feet, meaning that asymmetries disappeared. No significant changes were observed with PSp. Basic cardiovascular functions such as blood pressure and mean arterial pressure were also evaluated, showing significant decreases in systolic pressure and mean arterial pressure. These encouraging results suggest that regular physical activity, even if light in intensity and duration, improves overall hemodynamics and specifically raises perfusion in the lower limbs. These findings should be further explored with the aimof prevention and treatment of PVD. This research was financed by national funds through FCT - Foundation for Science and Technology, I.P. (Portugal), under the [UIDB/04567/2020] and [UIDP/ 04567/2020] programs. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Lower-Limb Perfusion and Cardiovascular Physiology Are Significantly Improved in Non-Healthy Aged Adults by Regular Home-Based Physical Activities-An Exploratory Study.

Common daily activities including walking might be used to improve cardiovascular health in the presence of disease. Thus, we designed a specific home-based physical activity program to assess cardiovascular indicators in an older, non-active, non-healthy population. Ten participants, with a mean age of 62.4 ± 5.6 years old, were chosen and evaluated twice-upon inclusion (D0), and on day 30 (D30)-following program application. Perfusion was measured in both feet by laser Doppler flowmetry (LDF) and by polarised spectroscopy (PSp). Measurements were taken at baseline (Phase 1) immediately after performing the selected activities (Phase 2) and during recovery (Phase 3). Comparison outcomes between D0 and D30 revealed relevant differences in Phase 1 recordings, namely a significant increase in LDF perfusion (p = 0.005) and a significant decrease in systolic blood pressure (p = 0.008) and mean arterial pressure (MAP) (p = 0.037). A correlation between the increase in perfusion and the weekly activity time was found (p = 0.043). No differences were found in Phase 2, but, in Phase 3, LDF values were still significantly higher in D30 compared with D0. These simple activities, regularly executed with minimal supervision, significantly improved the lower-limb perfusion while reducing participants' systolic pressure and MAP, taken as an important improvement in their cardiovascular status.

Blood flow ratio in the gastric conduit measured by laser Doppler flowmetry: A predictor of anastomotic leakage after esophagectomy.

Anastomotic leakage after esophagectomy is a common complication. Laser Doppler flowmetry (LDF) can quantitatively evaluate the blood flow in the gastric conduit. A total of 326 patients who underwent thoracoscopic/robot-assisted esophagectomy followed by gastric conduit reconstruction and end-to-side anastomosis were enrolled. We divided the gastric conduit into zones I (dominated by the right gastroepiploic vessels), II (dominated by the left gastroepiploic vessels), and III (perfused with short gastric vessels). Before pulling up the gastric conduit to the neck, LDF values were measured at the pylorus, the border between zones I and II (zone I/II), the border between zones II and III (zone II/III), and the gastric conduit tip (tip). The blood flow ratio was calculated as the LDF value divided by the LDF value at the pylorus. Anastomotic leakage developed in 32 of 326 patients. Leakage was significantly associated with the blood flow ratio at the tip (p < 0.001), but not at zone I/II, zone II/III, and the anastomotic site. The receiver-operating characteristic curve analysis identified an anastomotic leakage cutoff ratio of 0.41 (at the tip). A multivariate Cox analysis showed that a blood flow ratio <0.41 at the tip was an independent risk factor for anastomotic leakage (p < 0.001). Anastomotic leakage after esophagectomy was significantly associated with the blood flow ratio at the tip of the gastric conduit. Preservation of the blood supply to the tip via the gastric wall might contribute to a decreased incidence of anastomotic leakage.

Clinical effectiveness of comprehensive evaluation of soft tissue inflammation during preparation and treatment by dental implantation: A case report

At the Department of Orthopedic Dentistry and Orthodontics of the Ryazan State Medical University, one patient (A.) underwent after tooth extraction at the orthopedic rehabilitation using immediate prosthetics, and another patient (B.) was cured after extraction proceeded naturally. Both patients underwent dental implantation 4 months later. After tooth extraction and implantation, both patients underwent complex diagnostic observations on days 7, 20, and 30 through objective, instrumental, and laboratory follow-up of inflammation using the SchillerPisarev test, laser Doppler flowmetry (LDF), and assessment of the level of pro-inflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor (TNF-) and C-reactive protein (CRP). After tooth extraction on day 30, the clinical picture of both patients indicated complete subsidence of inflammation and stabilization of repair. The IL, CRP, and TNF- levels were 1.36 and B. 1.75 pg/mL, 0.68 and 0.88 mg/L, and 17.8 and 21.3 pg/mL in patients A and B, respectively. LDF indicators were 18.47 conventional units in patient A, and the microcirculation parameter was 11.46 conventional units in patient B. Thirty days after implantation, the levels of IL-6, CRP, and TNF- were 1.39 and 1.78 pg/mL, 0.74 and 0.92 mg/mL, and 18.9 and 20.2 pg/mL, respectively. The LDF values were 20.35 units in patient A, and the microcirculation parameter was 19.62 units in patient B. Comprehensive analysis of inflammation is necessary because of its high information content and ability to identify possible complications.

Effects of regular physical exercise on skin blood flow and cardiovascular risk factors in overweight and obese subjects

Objective: it is well known that low omentin levels and reduced bioavailability of nitric oxide (NO) are outgrowth of obesity. Besides, in obese subjects, microvascular dysfunction can be an initial stage of cardiovascular diseases. This situation can be evaluated with skin laser–Doppler flowmetry (LDF).Methods: in this study we investigated the effects of 12 weeks moderate physical exercise on microvascular reactivity and plasma levels of omentin and NO in 25 overweight and obese subjects. Control group was composed of 28 sedentary participants who were neither obese nor overweight. Microvascular reactivity was handled by measurement of skin blood flow from the ring finger of the right hand with LDF, which is a non–invasive method for evaluation. With this method, it was aimed to examine the post–occlusive reactive hyperemia response of the patients. None of the participants in both groups have never followed a regular exercise schedule in their life span.Results: with regular exercise, there was a statistically significant decrease in glucose (p=0.008), cholesterol (p=0.05), and triglyceride (p=0.048) levels, while body mass index, high–density lipoprotein, and low–density lipoprotein levels did not change significantly in overweight/obese group. Also, the omentin level significantly increased (p=0.01), but NO level did not change significantly. Moreover, the amount of change in omentin and NO levels measured before and after the physical exercise were significantly correlated (r=0.57). Considering the microcirculation, rest flow (p=0.001) and peak flow value of LDF (p=0.001) increased after the physical exercise.Conclusion: our study shows that moderate physical exercise affects microvascular reactivity and plasma levels of omentin in overweight and obese subjects.

Reactive hyperaemia augments local heat-induced skin hyperaemia.

What is the central question of this study? It is valuable to be able to monitor disease- or treatment-related changes in the microcirculation. Laser Doppler flowmetry with local heating allows non-invasive monitoring of the skin microcirculation and its ability to vasodilate. Does reactive hyperaemia augment the increase in skin blood flow elicited by local heating? What is the main finding and its importance? The addition of reactive hyperaemia to local heating results in greater vasodilatation than heating alone. Thus, reactive hyperaemia can augment local heat-induced hyperaemia in the skin. The skin circulation has been proposed as a model of generalized microvascular function that could be monitored non-invasively using laser Doppler flowmetry (LDF). The response to heat hyperaemia (HH) is commonly used to monitor disease- or treatment-related changes in microvascular function. We hypothesized that reactive hyperaemia would augment the increase in skin blood flow elicited by local heating. Fourteen healthy young adults were subjected to three different conditions: reactive hyperaemia (RH; skin temperature controlled at 33°C), heat hyperaemia (HH; 42°C held for 40min) and HH+RH. Two Peltier-controlled thermomodules with LDF probes were placed on the right forearm to monitor skin blood flow continuously. A cuff was placed on the right upper arm to elicit RH by inflation to 220mmHg for 5min. This procedure was performed with the skin temperature at 33°C and again after 40min of local heating to 42°C. Beat-by-beat mean arterial pressure (MAP) obtained by a photoplethysmographic sensor on the middle finger of the left hand allowed calculation of cutaneous vascular conductance (CVC) as LDF/MAP. Both HH and RH increased LDF (P<0.0001 and P<0.0001, respectively) and CVC (P=0.0001 and P<0.0001, respectively) above baseline values. The LDF and CVC values were significantly higher during HH+RH when compared with RH or HH alone (P<0.0001). In summary, HH+RH resulted in greater vasodilatation when compared with HH or RH alone. These results indicate that RH can augment local heat-induced hyperaemia in the skin.

Combined assessment of intestinal viability using laser doppler flowmetry and laser fluorescence spectroscopy

Introduction. The development of an objective non-invasive method for intraoperative assessment of intestinal viability remains urgent for modern surgery. In this context, the method of laser fluorescence spectroscopy (LFS) of coenzymes of oxidative metabolism, as well as a combination of this technique with the simultaneous use of laser Doppler flowmetry (LDF) seems promising. Materials and methods. The model of ischemia-reperfusion of the small intestine of 4 Californian Rabbits was used to study the relationship of the parameters of LFS and LDF with the histological picture. A model of intraoperative ischemia was used by temporarily clamping the trunk of the cranial mesenteric vascular bundle for 90 min, followed by intraoperative and postoperative reperfusion for 60 minutes and 24 hours, respectively. LDF and LFS data were recorded from intestine at the end of the intraoperative reperfusion period. 24 hours after the surgery, the animals were subjected to histologic evaluation of intestine ischemic changes, which were compared with the LDF and LFS data. Diagnostic value of LDF and LFS, and their combination for intraoperative assessment of intestinal viability were analyzed. Results. A significant correlation was found between the parameters of LDF, LFS and the degree of ischemic changes according to the histological data. The method of isolated assessment of the difference in the fluorescence of reduced nicotin adenine dinucleotide (NADH) before and after ischemia-reperfusion (77.3 %) has the greatest diagnostic value. The method has the highest sensitivity with a combination of differences in LDF and LFS values before and after ischemia-reperfusion (85.7 %) (P&lt;0.05). Conclusions. LFS, as well as its combination with LDF, is a useful method for objective assessment of intestinal viability, which requires further research and has potential for clinical use.

Adjunctive effects of laser therapy on somatosensory function and vasomotor regulation of periodontal tissues in patients with periodontitis: A randomized controlled clinical trial.

The purpose of this prospective study was to compare the changes in periodontal somatosensory function and microcirculation in patients with periodontitis following initial treatment with scaling and root planing (SRP) with or without adjuvant laser therapy. Twenty-four patients suffering from periodontitis were recruited and randomly allocated into a split-mouth design to either SRP combined laser therapy side (test side) or SRP only side (control side). All treatments were performed by the same investigator at a single visit. Laser Doppler Flowmetry (LDF) and Quantitative Sensory Testing (QST) were performed at baseline (W0), 1week (1W), 2weeks (2W), and 4weeks (4W) after treatment on both sides of the attached gingiva of the maxillary lateral incisor. Clinical examination including probing depth (PD) and bleeding on probing (BOP) was performed at W0, 2W, and 4W on both sides. Data were analyzed with two-way analysis of variance. PD and BOP significantly improved after treatment (P<0.001). LDF values were significantly decreased on both sides at all follow-up time points (P<0.001), temperature was increased only on the test side (P=0.017) whereas there was no significant change on the control side (P=0.792). Significantly less sensitivity was observed for all QST parameters (P<0.030) except for warmth detection after treatment. Adjunctive use of laser therapy did not provide any significant clinical advantage or additional effects on the recovery of periodontal somatosensory function or gingival microcirculation in the present study.

Evaluation of the Effect of Hyaluronic Acid Application on the Vascularization of Free Gingival Graft for Both Donor and Recipient Sites with Laser Doppler Flowmetry: A Randomized, Examiner-Blinded, Controlled Clinical Trial.

This study aimed to evaluate with laser Doppler flowmetry (LDF) the effect of topical hyaluronic acid (HA) application on the vascularization of free gingival graft (FGG) donor and recipient sites during the early wound healing period and to investigate the effect of HA application on the dimensional change of the FGG. Forty systemically healthy, nonsmoking patients who required FGG due to insufficient amount of attached gingiva in a partial edentulism were randomly assigned to a study group: test (FGG+HA) or control (FGG alone). The LDF values of the donor and recipient sites were measured in both groups before the operation and at 4, 7, 10, 14, and 30 postoperative days. LDF measurement of the graft was performed as soon as the graft was taken from the palatal site. FGG dimensions (width, height, and thickness) were assessed and recorded at baseline and on day 30, as well as the percentage of the changes in these values. LDF values of the recipient site in the FGG+HA group were found to be statistically higher than those in the control group on days 4 and 7 (P = .013 and P = .020, respectively); however, no differences were found for days 10, 14, and 30. Additionally, no differences were found for the LDF values of the palatal site between the FGG+HA and control groups (P > .05) at all examined time points. The height of the graft measured on day 30 was statistically higher in the FGG+HA than the control group (P < .001). The percentage change in thickness and height of the FGG was statistically lower in the FGG+HA than control group (P = .028 and P < .001, respectively). Application of HA on the recipient bed under the FGG at the first week of healing allows the formation of a well-vascularized layer, which acts as a barrier against tissue tensions by functioning as a scaffold between the recipient bed and FGG, thus reducing the shrinkage of the graft, especially in the vertical direction. This study further showed that the graft taken from the donor site had a remaining blood perfusion value of its own.

Approaches to improve the predictive value of laser Doppler flowmetry in detection of microcirculation disorders in diabetes mellitus.

Laser Doppler flowmetry is widely used in scientific studies of blood microcirculation but constrained in clinical use due to the low diagnostic significance. This research is aimed at creation of approaches to prognostic value increase in detection of microcirculation disorders in patients with type 2 diabetes mellitus. The study included 10 volunteers and 10 patients with t2DM. Participants were observed using postural-heating test with LAKK-02 complex. We calculated median microcirculation for each period and then held a retroactive classification of the surveyed groups. Statistically significant differences between groups were found in the perfusion during the combination of postural and heating impacts. Conversion of this perfusion in the relative index (Irel) (relative to the baseline perfusion), allowed us to increase the significance of the differences. The value of AUC (95% CI) during the ROC-analysis in reverse classification was 0.81 (0,60-1,0) for the period of the impacts combination, and 0.93 (0,81-1,0) for Irel index. We demonstrated the possibility of using LDF method to achieve predictive value in the detection of microcirculatory disorders in an individual patient with diabetes. This extends the perspectives of the method beyond the purely scientific research.

Diurnal variations and pulpal status: is there a need for FFT besides LDF?

The aim of this article was to investigate the use of laser Doppler flowmetry (LDF) combined with a fast Fourier transformation (FFT). LDF data in relation to three different scenarios were evaluated: (a) LDF records of a right central upper incisor of one patient were used for FFT analysis. These records were obtained by means of 30 pre-manufactured splints, handled by dentists without any experience in LDF recording. (b) Diurnal variations in one patient were analysed with LDF and FFT using 11 splints by one and same experienced investigator at four specific moments of the day. (c) Pulpal status was analysed using 17 splints. Eleven for a patient, standing as case model and six splints for six other patients. In this specific group, each patient had one vital and one non-vital central maxillary incisor and was analysed separately by LDF and FFT. The data of assessment (b) showed diurnal variations on LDF values of almost 80%, indicating that LDF registration is best performed in the same time period of the day. Data verification with FFT confirmed the findings without FFT of assessment (a) and (b). In assessment, (c) FFT demonstrated a clear distinction between a vital and a non-vital pulp for those cases with one vital tooth and one root canal treated tooth. In those cases with one vital incisor and the other traumatised, FFT was undeterminated. Considered that FFT was obtained after LDF recording and remained undeterminated for a decision in cases with decreasing pulpal blood flow in time, the added value of FFT in pulpal traumatology was minimal.

Transcutaneous oximetry and laser Doppler flowmetry values in patients with chronic skin ulcers treated with platelet rich plasma and stromal vascular fraction cells: a pilot study

Stromal vascular fraction cells (SVFs) hold great promise for use in regenerative medicine applications, as a result of their ability to promote the healing process through in situ differentiation and the secretion of paracrine factors. The aim of this paper was to evaluate whether and how the topical application of SVF with platelet-rich plasma (PRP) for the treatment of chronic skin ulcers modified the cutaneous perfusion of the treated areas. Perilesional laser Doppler flowmetry (LDF) and transcutaneous oximetry (tcpO2) values were recorded for a 3-month period in 15 patients with chronic skin ulcers of various etiologies, who had been previously treated with single co-administered perilesional and intralesional injections of SVF+PRP. No significant differences were found between pretreatment, 1 month, and 3 month posttreatment values regarding both LDF values (basal: p = 0.10 and declivous: p = 0.0976) and declivous tcpO2 levels (p = 0.0804). The only significant difference reported was between pretreatment and 3-month posttreatment basal tcpO2 levels (p = 0.0466). These results may reflect improved subcapillary circulation of the treated areas at 3 months postinjection, without a significant improvement in capillary perfusion. Level of Evidence: Level IV, therapeutic study.

Minimally invasive dorsal sympathicotomies for the treatment of hyperhidrosis: palmar microcirculatory assessment as an intraoperative-aid

Endoscopic transthoracic sympathicotomy has proven to be an effective and durable surgical treatment for severe primary hyperhidrosis. Anyhow, in some cases, especially in overweight patients, a thick overlying subpleural fat may obscure the sympathetic chain, precluding access to the ganglia and partial or total completion of the procedure. The aim of this study was to assess the value of palmar laser Doppler flowmetry (LDF) as an intraoperative-aid during minimally invasive dorsal sympathicotomies (T3) for the treatment of primary palmar hyperhidrosis. The method was tested during 40 upper dorsal video-assisted minimally invasive sympathicotomies in 20 patients with bilateral palmar primary hyperhidrosis. The mean baseline LDF values were 36.05 pU (SD = 21.85 pU). The mean immediate postoperative LDF values were 75.94 pU (SD = 37.89 pU). A statistically significant difference was observed between preoperative and immediate (about 5 s after the sympathicotomies) postoperative values (p = 0.00000009). According to our data, LDF allowed to obtain reliable and fast intraoperative evidence of a correct section of T3 ganglia. As such, we recommend LDF as a useful intraoperative tool when dealing with dorsal sympathicotomies for the treatment of palmar hyperhidrosis, both for the unexperienced surgeon and when the sympathetic chain is not clearly visualized. Level of Evidence: Level IV, therapeutic study.

Laser Doppler flowmetry: reproducibility, reliability, and diurnal blood flow variations

The aim of this investigation was (1) to evaluate the reliability of laser Doppler flowmetry (LDF) taking into consideration the use of a silicone splint and the inclination of the probe towards the buccal surface of a human tooth and (2) to determine whether diurnal variations of pulpal blood flow can be registered by means of LDF. Forty-one splints were made by one and the same principal investigator for the registration of pulpal blood flow in vivo in a maxillary right central incisor. Thirty dentists, without experience in LDF recording, were then asked to drill a right-angled shaft in a pre-manufactured splint with a referral point at 2mm from the enamel-cement border central on the buccal surface of the right central upper incisor. The remaining 11 splints were handled by the principal investigator. The shafts in the 30 splints were analysed using Cone Beam CT imaging of the axial and sagittal angles and compared these to the 11 shafts prepared by the trained principal investigator. LDF was recorded for 90s in each splint and statistically analysed. LDF values without the use of a splint were statistically significantly different (p < 0.05) and the variance was greater, indicating the superiority of splint use. Significant diurnal variations on LDF values were observed, indicating that special attention should be paid to registration during the day, especially when multiple measurements are to be compared.

Assessment of local blood flow with laser Doppler flowmetry in irradiated mandibular and frontal bone, an experiment in Göttingen minipigs

The aim of this study was to investigate local blood flow changes in the mandibular bone compared to the os frontale after irradiation in various doses. This study used an animal experiment with 16 female Göttingen minipigs. Three groups of four animals were irradiated with equivalent doses of 25, 50 or 70 Gray on the mandible and os frontale and four animals served as control. Three months after irradiation laser Doppler flowmetry (LDF) was used to record local blood flow on the left mandible and in the irradiated area on the os frontale. At 6 months measurements were repeated. Descriptive and univariate analyses were conducted and p-values lower than 0.05 were considered statistically significant. Local blood flow measurements in the mandible were significantly higher compared to the os frontale. In the os frontale and mandible there was no significant change in the measurements with increasing irradiation dose. We found a non-significant decrease in LDF values with an increase in radiation dose in the mandible and non-significant changes in the os frontale at 3 and 6 months. We consider this to represent the process of on-going fibrosis affecting the local blood flow in the mandible.

Assessment of cutaneous microcirculation in unaffected skin regions by transcutaneous oxygen saturation monitoring and Laser Doppler flowmetry in systemic sclerosis

We assessed the cutaneous microcirculatory reactivity of a clinically unaffected skin region in patients with systemic sclerosis (SSc) compared to healthy controls by measuring transcutaneous oxygen saturation (TcPO2) and Laser Doppler flowmetry (LDF).Twelve consecutive patients with SSc and twelve healthy controls were subjected to TcPO2 monitoring and LDF during cuff-induced ischemia and reactive hyperemia in order to measure the skin oxygen tension and the microcirculatory blood flow. Mean minimal and maximal values of oxygen tension and blood flow, time to peak (TTP), and declining slopes after peaking (slope) were compared between patients with SSc and controls.Compared to the controls, TcPO2 values in SSc were similar during ischemia and diminished during reactive hyperemia, with longer TTP, and a slower return to baseline (-60% vs. -58% , p = 1.000, +76% vs. +210% , p = 0.047, 137 s vs. 108 s, p = 0.028, -0.009% /s vs. -0.019% /s, p = 0.021, respectively). LDF values, however, did not differ significantly between patients with SSc and controls.Unaffected skin regions of SSc patients showed a significantly diminished postischemic vasodilatory reactivity when assessed by TcPO2 monitoring, but not by LDF, indicating that vasculopathy may represent an early mechanism in the onset of skin sclerosis. TcPO2 measurement may help to detect changes in the microcirculation in SSc with no skin affection.

A blinded randomized assessment of laser Doppler flowmetry efficacy in standardizing outcome from intraluminal filament MCAO in the rat.

Laser Doppler flowmetry (LDF) is widely used for estimating cerebral blood flow changes during intraluminal middle cerebral artery occlusion (MCAO). No investigation has systematically examined LDF efficacy in standardizing outcome. We examined MCAO histologic and behavioral outcome as a function of LDF measurement. Rats were subjected to 90min MCAO by 4 surgeons having different levels of MCAO surgical experience. LDF was measured in all rats during ischemia. By random assignment, LDF values were (Assisted) or were not (Blinded) made available to each surgeon during MCAO (n=12-17 per group). Neurologic and histologic outcomes were measured 7 days post-MCAO. A second study examined LDF effects on 1-day post-MCAO outcome. Pooled across surgeons, intra-ischemic %LDF change (P=0.12), neurologic scores (Assisted vs. Blinded=14±6 vs. 13±7, P=0.61, mean±standard deviation) and cerebral infarct volume (162±63mm(3)vs. 143±86mm(3), P=0.24) were not different between groups. Only for one surgeon (novice) did LDF use alter infarct volume (145±28mm(3)vs. 98±61mm(3), P=0.03). LDF use decreased infarct volume coefficient of variation (COV) by 35% (P=0.02), but had no effect on neurologic score COV. We compared intraluminal MCAO outcome as a function of LDF use. LDF measurement altered neither neurologic nor histologic MCAO outcome. LDF did not decrease neurologic deficit COV, but did decrease infarct volume COV. LDF may allow use of fewer animals if infarct volume is the primary dependent variable, but is unlikely to impact requisite sample sizes if neurologic function is of primary interest.

Noninvasive Transcutaneous Monitoring in Long-Term Follow-Up of Patients With Thromboangiitis Obliterans Treated With Intravenous Iloprost.

We evaluated the effectiveness of intravenous iloprost (IVI) in outpatients with thromboangiitis obliterans (TAO) and lower limb noninvasive transcutaneous monitoring (TCM) at follow-up (FU). Ten consecutive patients with TAO underwent IVI therapy. Transcutaneous oxygen (TcPo 2) and carbon dioxide (TcPco 2) determination and laser Doppler flowmetry (LDF) were performed before and after IVI at 3, 6, and 12 months of FU. Clinical response was positive in 7 patients, whereas 3 nonresponders underwent a second IVI cycle with 1 showing a late positive clinical response. After 12 months of FU, all patients were alive without amputations. Supine and dependent TcP2 levels significantly improved (P < .005). Hallux LDF values showed significant change with the maximal hyperemic test at 44°C (P < .005). Forefoot maximal hyperemic test at 44°C LDF (P < .005) and improved venous arterial reflex (P < .05) showed statistically significant time evolution. We demonstrated some degree of IVI effectiveness and evaluated TCM in patients with TAO.

Effect of postprandial thermogenesis on the cutaneous vasodilatory response during exercise.

To examine the effect of postprandial thermogenesis on the cutaneous vasodilatory response, 10 healthy male subjects exercised for 30 min on a cycle ergometer at 50% of peak oxygen uptake, with and without food intake. Mean skin temperature, mean body temperature (Tb), heart rate, oxygen uptake, carbon dioxide elimination, and respiratory quotient were all significantly higher at baseline in the session with food intake than in the session without food intake. To evaluate the cutaneous vasodilatory response, relative laser Doppler flowmetry values were plotted against esophageal temperature (Tes) and Tb. Regression analysis revealed that the [Formula: see text] threshold for cutaneous vasodilation tended to be higher with food intake than without it, but there were no significant differences in the sensitivity. To clarify the effect of postprandial thermogenesis on the threshold for cutaneous vasodilation, the between-session difference in the Tes threshold and the Tb threshold were plotted against the between-session difference in baseline Tes and baseline Tb, respectively. Linear regression analysis of the resultant plot showed significant positive linear relationships (Tes: r = 0.85, P < 0.01; Tb: r = 0.67, P < 0.05). These results suggest that postprandial thermogenesis increases baseline body temperature, which raises the body temperature threshold for cutaneous vasodilation during exercise.