Intraoperative Blood Flow Measurements Research Articles

Treatment of Recurrent, Twice Coiled, Previously Ruptured Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Aneurysm With Excision and End-to-End Anastomosis: 2-Dimensional Operative Video.

Anterior inferior cerebellar artery-posterior inferior cerebellar artery (AICA-PICA) variant is a well-established variant of the vertebrobasilar system. AICA-PICA aneurysms are extremely rare.1-3 There are only 12 cases reported in the literature.1-3 Here, we are presenting a case of a previously ruptured AICA-PICA dissecting aneurysm which had undergone coil embolization twice at an outside institution. The aneurysm continued to grow, and therefore, the patient was transferred to our institution for definitive treatment. Placement of a flow diverter was felt not to be feasible because of the acute bend of the vessel at the neck of the aneurysm. After a retrosigmoid craniotomy, the aneurysm sac was opened to untether the coil mass from the neck of the aneurysm. Clip reconstruction was attempted but intraoperative blood flow measurements demonstrated no flow in the distal outflow artery, indicating that the clip was occluding the parent vessel at the neck because of the challenging geometry and atherosclerosis. We then proceeded with an excision and end-to-end anastomosis of the AICA-PICA. The details of vascular reconstruction while the inflow and outflow arteries are at acute angle are described. Intraoperative indocyanine video angiography demonstrated complete exclusion of the aneurysm from the circulation and patency of the bypass. Postoperative computed tomography angiography demonstrated bypass patency. Postoperatively, the patient required a temporary external ventricular drain for hydrocephalus; however, she was eventually discharged home without any neurological deficits. The patient gave informed consent for the surgery and video recording. Institutional Review Board approval was deemed unnecessary.

#532 Association between blood flow measured within 30 days from AV access creation and the risk of thrombosis

Abstract Background and Aims The use of arteriovenous (AV) access for hemodialysis (HD) is hampered by the risk of dysfunction and thrombosis. Various factors affect the risk of AV access thrombosis, such as age, female sex, hematocrit, vessels’ diameter and anatomy, and patients’ comorbidities (e.g. diabetes mellitus, thrombophilia, chronic inflammatory disease). Previous studies have reported contradictory results on the prognostic value of intraoperative blood flow (Qa) measurements. Finally, only few studies have investigated the association between postoperative Qa measurements and thrombosis risk. Therefore, current guidelines report that there is not enough evidence to suggest routine assessment of AV access Qa for surveillance. This study aimed to analyze the association between Qa, measured at the first post-operative visit (within 30 days from creation), and thrombosis risk, in distal and proximal autologous AV fistulae (dAVF and pAVF), and AV grafts (AVG). Method This retrospective cohort study included all AV accesses created in San Paolo Hospital (Milan, IT) between January 1st 2013 and December 31st 2022, with a post-operative Qa measurement available within 30 days from the date of creation. AV accesses were classified as dAVF, pAVF and AVG. Qa was measured by ultrasound as the product of the cross-sectional area and the time-averaged mean velocity, in the feeding artery. The thrombosis-free survival of dAVF, pAVF and AVG was plotted using the Kaplan Meier method. The association between Qa and the risk of thrombosis was studied by Cox proportional hazard models, adjusted for patient's age and sex. Non-linearity was assessed using natural splines. Results A total of 218 AV accesses (92 dAVF, 76 pAVF, and 50 AVG) were created in 191 patients. At baseline, patients had a median age of 69 years, 70% were male, 42% were already on HD treatment, and overall, they had a high prevalence of hypertension, diabetes mellitus and cardiovascular comorbidities. At first post-operative visit, median Qa was 922 [698, 1278] ml/min, 1260 [917, 1825] ml/min, and 1665 [1195, 2508] ml/min, respectively for dAVF, pAVF, and AVG (p <0.001). During a median follow up time of 1.35 [0.55, 2.62] years, 66 AV access thrombosis occurred. The thrombosis-free survival rates for dAVF, pAVF and AVG were 84%, 97%, and 51% at 1 year, and 63%, 66%, and 19% at 5 years (Fig. 1). For dAVF we found a significant L-shaped association between Qa measured at the first post-operative visit and thrombosis risk, with the lowest risk found at Qa of 1289 ml/min and an exponential risk increase for dAVF with Qa <800 ml/min (Fig. 2). Particularly, for dAVF with Qa < 1289 ml/min, we found a 39% increased risk of thrombosis for every 100 ml/min decrease in Qa (aHR 1.39, 95% CI 1.10-1.75, p 0.006). In pAVF, Qa showed a trend of inverse linear association with the risk of thrombosis, although not reaching statistical significance (aHR 1.06, 95% CI 0.96-1.17, p 0.24, for every 100 ml/min decrease in Qa). In AVG, Qa was not associated with the risk of thrombosis (aHR 1.01, 95% CI 0.97-1.06, p 0.57, for every 100 ml/min decrease in Qa). Conclusion In our cohort we found that Qa, measured at the first post-operative visit, is associated with the risk of thrombosis in dAVF, but not in pAVF and AVG. In particular, in dAVF the association is non-linear with the lowest risk in our cohort found at Qa equal to 1289 ml/min, with an exponentially increasing risk for Qa <800 ml/min. Our findings suggest that post-operative flow assessment may be a useful tool to identify dAVF at higher risk of thrombosis and allow a closer monitoring or possible preventive interventions.

Intraoperative Blood Flow Analysis of Free Flaps with Arteriovenous Loops for Autologous Microsurgical Reconstruction

Background: Arteriovenous (AV) loops help to overcome absent or poor-quality recipient vessels in highly complex microvascular free flap reconstruction cases. There are no studies on blood flow and perfusion patterns. The purpose of this study was to evaluate and compare intraoperative hemodynamic characteristics of AV loops followed by free tissue transfer for thoracic wall and lower extremity reconstruction. Methods: this prospective clinical study combined Transit-Time Flowmetry and microvascular Indocyanine Green Angiography for the assessment of blood flow volume, arterial vascular resistance and intrinsic transit time at the time of AV loop construction and on the day of free flap transfer. Results: A total of 11 patients underwent AV loop creation, of whom five required chest wall reconstruction and six required reconstruction of the lower extremities. In seven of these cases, the latissimus dorsi flap and in four cases the vertical rectus abdominis myocutaneous (VRAM) flap was used as a free flap. At the time of loop construction, the blood flow volume of AV loops was 466 ± 180 mL/min, which increased to 698 ± 464 mL/min on the day of free tissue transfer (p > 0.1). After free flap anastomosis, the blood flow volume significantly decreased to 18.5 ± 8.3 mL/min (p < 0.001). There was no significant difference in blood flow volume or arterial vascular resistance between latissimus dorsi and VRAM flaps, nor between thoracic wall and lower extremity reconstruction. However, a significant correlation between the flap weight and the blood flow volume, as well as to the arterial vascular resistance, was found (p < 0.05). Conclusion: This is the first study to perform intraoperative blood flow and hemodynamic measurements of AV loops followed by free tissue transfer. Our results show hemodynamic differences and contribute to deeper understanding of the properties of AV loops for free flap reconstruction.

The Impact of Intraoperative Graft Blood Flow Measurement on Early Graft Function

The aim of this study is to evaluate the impact of intraoperative allograft vascular flow on early kidney graft function. A total of 159 patients underwent kidney transplantation from January 2017 to March 2022 at Linkou Chang Gung Memorial Hospital. Graft arterial and venous blood flow was measured separately with a transient time flowmeter (Transonic HT353; Transonic Systems, Inc, Ithaca, NY, United States) after ureteroneocystostomy. The early outcomes, including the postoperative creatinine level, were analyzed accordingly. There were 83 males and 76 females, with a mean age of 44.5 years. The mean graft arterial flow measured was 480.6 mL/min, and the mean venous flow was 506.2 mL/min. Delayed graft function (DGF) incidence was 36.5%, 32.5%, and 40.8% in total, living, and deceased donor groups, respectively. Living donor and deceased donor kidney transplantation were analyzed separately. In the DGF subgroup, there were lower graft venous flows, higher body mass index (BMI), and more male patients in the living kidney transplant group. Similarly, the deceased donor kidney transplantation group with delayed graft function tended to have higher body height, higher body weight, higher BMI, and more diabetes mellitus. The multivariate analysis showed that lower graft venous blood flow (odds ratio [OR]=0.995, P=.008) and higher BMI (OR=1.144, P=.042) were significantly correlated with delayed graft function in living donor kidney transplantations. In the deceased donor group, a multivariate analysis of risk factors showed that BMI had a significant correlation with delayed graft function (OR=1.41, P=.039). Graft venous blood flow was significantly associated with delayed graft function in living donor kidney transplantation, and high BMI was correlated with DGF in all patients receiving kidney transplantation.

Comparison of the mid-term clinical efficacy and short-term complications of Y-type coronary artery bypass grafting and sequential bypass grafting of the great saphenous vein: a retrospective cohort study.

BackgroundThis study sought to compare and evaluate the clinical efficacy and safety of Y-type coronary artery bypass grafting (CABG) and sequential CABG. However, the prognosis and complication rate of the two treatments are different. Therefore, we need to systematically compare the efficacy and safety of the two surgical schemes.MethodsA total of 112 patients who underwent Y-type CABG and 113 patients who underwent sequential CABG were selected from January 2020 to December 2020. The patients undergoing Y-type CABG of the great saphenous vein (SV) were classified as the experimental group, and those undergoing sequential anastomosis were classified as the control group. The intraoperative blood flow at each anastomotic site of the venous sequential CABG, left ventricular ejection fraction (LVEF), and left ventricular diastolic diameter (LVEDD) at the end of 3 months, 6 months, and 1 year after surgery, the incidence rate of major adverse cardiovascular events, and coronary angiography (CAG) after readmissions due to similar symptoms were compared between the 2 groups. The bridging vascular blockage rate was also determined.ResultsThere was no significant difference in cardiac function between the 2 groups in the short term, and the incidence of major adverse cardiovascular events in the 2 groups mainly occurred in the middle-postoperative period (1 year after surgery) or later. There was no statistical difference in the intraoperative real-time blood flow measurements at each anastomosis of the venous bridge between the 2 groups. Compared to the control group, the LVEF of the experimental group was significantly increased at the 1-year follow-up point (51.6±5.1 vs. 67.6±5.6, P=0.001). During the operation of Y-type coronary artery bypass grafting, the incidence of major adverse cardiovascular events, vascular bridge, and anastomotic blockage were significantly decreased (16 vs. 39, P=0.023).ConclusionsLarge SV Y-type CABG can improve postoperative left heart function and reduce the incidence of postoperative adverse events, which may be of great significance for improving the postoperative mid-term survival rate of patients.

One-donor, two-recipient extracranial-intracranial bypass series for moyamoya and cerebral occlusive disease: rationale, clinical and angiographic outcomes, and intraoperative blood flow analysis.

Cerebral extracranial-intracranial (EC-IC) direct bypass is a commonly used procedure for ischemic vasculopathy. A previously described variation of this technique is to utilize one donor artery to supply two recipient arteries, which the authors designate as 1D2R. The purpose of this study is to present a single surgeon's series of 1D2R direct bypasses for moyamoya and ischemia using detailed clinical, angiographic, and intraoperative blood flow measurement data. To the authors' knowledge, this is the largest series reported to date. Hospital, office, and radiographic imaging records for all patients who underwent cerebral revascularization using a 1D2R bypass by the senior author were reviewed. The patients' demographic information, clinical presentation, associated medical conditions, intraoperative information, and postoperative course were obtained from reviewing the medical records. A total of 21 1D2R bypasses were performed in 19 patients during the study period. Immediate bypass patency was 100% and was 90% on delayed follow-up. The mean initial cut flow index (CFI(i)) was 0.64 ± 0.33 prior to the second anastomosis and the mean final value (CFI(f)) was 0.94 ± 0.38 after the second anastomosis (p < 0.001). The overall bypass flow increased on average by 50% (mean 17.9 ml/min, range -10 to 40 ml/min) with the addition of the second anastomosis. There was no significant difference in the overall flow measurements when the end-to-side anastomosis or side-to-side anastomosis was performed first. There was a statistically significant difference in the proportion of patients with a modified Rankin Scale (mRS) score of 0 or 1 postoperatively compared to preoperatively (p < 0.01). Through the application of Poiseuille's law, the authors analyzed flow dynamics, deduced the component vascular resistances based on an analogy to electrical circuits and Ohm's law, and introduced the new concepts of "second anastomosis relative augmentation" and "second anastomosis sink index" in the evaluation of 1D2R bypasses. The application of the 1D2R technique in a series of 19 consecutive patients undergoing direct EC-IC bypass for flow augmentation demonstrated high patency rates, statistically significantly higher CFIs compared to 1D1R, and improved mRS scores at last clinical follow-up. Additionally, the technique allows a shorter dissection time and preserves blood flow to the scalp. The routine utilization of intraoperative volumetric flow measurements in such surgeries allows a deeper understanding of the hemodynamic impact on individual patients.

Laser speckle imaging to evaluate scalp flap blood flow during closure in neurosurgical procedures.

Background: To measure the degree of relative ischemia caused by skin closure, we explored the potential utility of intraoperative surface blood flow measurement with laser speckle imaging (LSI).Methods: Prospective observational study of eight subjects that underwent intraoperative LSI during elective cranial neurosurgical procedures at the time of skin closure.Results: Seven 1st time incisions, with closure techniques including sutures (n = 3), staples (n = 3), and one after galeal sutures. When compared to the control region, there was a mean 63.7% reduction in flow across all seven subjects (range 18.7–95.32%). Comparing by closure type, a higher flow reduction in the three subjects with suture closure (80.7% reduction) compared to staples (61.9% reduction, P = 0.0379). One subject had a complex wound where tightening and loosening of sutures were performed to ensure adequate perfusion. Suturing resulted in significantly more local decreased flow compared to staples (P < 0.0001).Conclusion: These findings demonstrate the relative feasibility of using LSI for preoperative vascular flow assessment in planning complex incision closure. These data also provide preliminary support for the hypothesis that skin closure itself causes relative ischemia compared to deep approximation or cautery of the skin edge and that the relative ischemia from staples closure is generally less than from suture closure.

Intraoperative assessment of femoral head perfusion during surgical hip dislocation for slipped capital femoral epiphysis

Avascular necrosis is the most devastating complication of slipped capital femoral epiphysis, leading to collapse of the femoral head, increased risk of osteoarthritis and the requirement of early total hip arthroplasty. It is believed that intraoperative femoral head perfusion assessment may be an accurate predictor of post-operative avascular necrosis (radiographic collapse). At our institution, femoral head perfusion is assessed intraoperatively during all sub-capital realignment procedures. We hypothesize that our method is accurate in predicting the risk of developing post-operative avascular necrosis. In this retrospective study, we collected data from all patients that had intraoperative blood flow measurements during sub-capital realignment procedures. We correlated this with long-term radiographs looking for radiographic collapse. The intraoperative femoral head perfusion assessments during sub-capital realignment procedures for slipped capital femoral epiphysis at our institution, between January 2015 and March 2020 inclusive were assessed for reliability. In total, 26 of 35 patients had intraoperative femoral head perfusion present. Only 2 (8%) of these patients developed radiographic collapse. In contrast, 7 (78%) of the 9 patients who did not have femoral head perfusion present intraoperatively developed radiographic collapse, indicating that our method may be reliable in predicting a patient’s post-operative risk of developing avascular necrosis.

Intraoperative use of transit time flow measurement improves patency of newly created radiocephalic arteriovenous fistulas in patients requiring hemodialysis.

The autologous arteriovenous fistula is the primary choice to establish hemodialysis access without high failure rates. Intraoperative ultrasound flow measurements of newly created autologous arteriovenous fistulas represent a possibility of quality control and may therefore be a tool to assess their functionality. The aim of our study was to correlate intraoperative blood flow with access patency. Between March 2012 and March 2015, intraoperative transit time flow measurements were collected on 89 patients. Measurements were performed 5-10 min after the creation of a standardized anastomosis using 3-6 mm flow probes. To examine the correlation between intraoperative blood flow and access patency, groups of patients with high (> 200 mL/min) versus low flow (< 200 mL/min) were enrolled. Patients were assessed clinically and with ultrasound every 3 months. Data were analyzed retrospectively. In the current short-term follow-up, including 89 patients (age 62 ± 3 years), 61 (68.5%) of the autologous arteriovenous fistulas were currently being used in an observation period ranging from 3 months to 3 years (mean observation period 546 ± 95 days) postoperatively. The intraoperative blood flow in patients with functioning autologous arteriovenous fistula (78) was significantly higher than that of patients without functioning autologous arteriovenous fistulas (407 ± 25 vs 252 ± 42 mL/min, respectively; p < 0.005) (11). The intraoperative measurement of blood flow is a useful tool to predict the outcome of maturation in autologous arteriovenous fistula. With this method, technical problems can be detected and corrected intraoperatively. Routine implementation of intraoperative flow measurements has to be examined by prospective controlled trials.

The cut flow index revisited: utility of intraoperative blood flow measurements in extracranial-intracranial bypass surgery for ischemic cerebrovascular disease.

In extracranial-intracranial (EC-IC) bypass surgery, the cut flow index (CFI) is the ratio of bypass flow (ml/min) to donor vessel cut flow (ml/min), and a CFI ≥ 0.5 has been shown to correlate with bypass patency. The authors sought to validate this observation in a large cohort of EC-IC bypasses for ischemic cerebrovascular disease with long-term angiographic follow-up. All intracranial bypass procedures performed at a single institution between 2003 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and analyzed according to bypass patency with univariate and multivariate statistical analyses. A total of 278 consecutive intracranial bypasses were performed during the study period, of which 157 (56.5%) were EC-IC bypasses for ischemic cerebrovascular disease. Intraoperative blood flow measurements were available in 146 patients, and angiographic follow-up was available at a mean of 2.1 ± 2.6 years after bypass. The mean CFI was significantly higher in patients with patent bypasses (0.92 vs 0.64, p = 0.003). The bypass patency rate was 83.1% in cases with a CFI ≥ 0.5 compared with 46.4% in cases with a CFI < 0.5 (p < 0.0001). Adjusting for age, sex, diagnosis, and single versus double anastomosis, the CFI remained a significant predictor of bypass patency (p = 0.001; OR 5.8, 95% CI 2.0-19.0). A low CFI was also associated with early versus late bypass nonpatency (p = 0.008). A favorable CFI portends long-term EC-IC bypass patency, while a poor CFI predicts eventual bypass nonpatency and can alert surgeons to potential problems with the donor vessel, anastomosis, or recipient bed during surgery.

Local Cerebral Hemodynamics after Superficial Temporal Artery-Middle Cerebral Artery Bypass in Patients with Symptomatic Carotid Occlusions.

Context:Physiological insights into blood flow alterations in cortical vessels after superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery are important for the prognosis of bypass sustainability and hemodynamic patency.Aims:This study aims to assess the impact of STA-MCA bypass on local hemodynamics for patients with symptomatic carotid occlusions and Moyamoya disease.Settings and Design:This article presents a prospective nonrandomized study of intraoperative blood flow measurements in cortical branches of MCA and donor vessel before and after cerebral revascularization.Materials and Methods:Evaluation of local hemodynamic parameters was established for 112 patients with symptomatic carotid occlusive disease and cerebrovascular insufficiency during STA-MCA bypass surgery. We used intraoperative Doppler ultrasonography (89 patients – 72%), flowmetry (56 cases – 50%), and in 33 cases both methods. For physical justification of observed facts, we performed computational simulation with OpenFOAM CFD framework using Navier-Stokes nonstationary hemodynamic model.Statistical Analysis Used:All calculations were performed with IBM SPSS Statistics version 10.0 software. We used parametric (Z-test and Student's t-test) and nonparametric models (Wilcoxon, Mann–Whitney). For categorical values, we used Fisher's exact test.Results:Local cerebral hemodynamics after revascularization surgery significantly depended on initial perfusion deficit and the ability of bypass to reverse the blood flow in proximal parts of cortical artery (86 cases, 77%). Mechanism of cortical blood flow alteration was related to donor vessel cut flow value and potential consumption threshold of acceptor artery.Conclusions:Knowledge of hemodynamic principles of flow redistribution after STA-MCA bypass is important to improve bypass stainability and leads to better revascularization results.

Intraoperative Renal Resistive Index as an Acute Kidney Injury Biomarker: Development and Validation of an Automated Analysis Algorithm

Intraoperative Doppler-determined renal resistive index (RRI) is a promising early acute kidney injury (AKI) biomarker. As RRI continues to be studied, its clinical usefulness and robustness in research settings will be linked to the ease, efficiency, and precision with which it can be interpreted. Therefore, the authors assessed the usefulness of computer vision technology as an approach to developing an automated RRI-estimating algorithm with equivalent reliability and reproducibility to human experts. Retrospective. Single-center, university hospital. Adult cardiac surgery patients from 7/1/2013 to 7/10/2014 with intraoperative transesophageal echocardiography-determined renal blood flow measurements. None. Renal Doppler waveforms were obtained retrospectively and assessed by blinded human expert raters. Images (430) were divided evenly into development and validation cohorts. An algorithm for automated RRI analysis was built using computer vision techniques and tuned for alignment with experts using bootstrap resampling in the development cohort. This algorithm then was applied to the validation cohort for an unbiased assessment of agreement with human experts. Waveform analysis time per image averaged 0.144 seconds. Agreement was excellent by intraclass correlation coefficient (0.939; 95% confidence interval [CI] 0.921 to 0.953) and in Bland-Altman analysis (mean difference [human-algorithm] -0.0015; 95% CI -0.0054 to 0.0024), without evidence of systematic bias. The authors confirmed the value of computer vision technology to develop an algorithm for RRI estimation from automatically processed intraoperative renal Doppler waveforms. This simple-to-use and efficient tool further adds to the clinical and research value of RRI, already the "earliest" among several early AKI biomarkers being assessed.

Predicting arteriovenous fistula maturation with intraoperative blood flow measurements.

To establish the criteria for intraoperative blood flow measurements taken at the time of autologous arteriovenous fistula (AVF) construction to predict future access maturation and thereby avoid waiting periods for futile fistulas to declare themselves. From April 2006 through to March 2007 consecutive patients undergoing native AVF construction at one institution underwent intraoperative measurements of blood flow using transit-time ultrasound technology. No action was taken based upon the flow measurement at the time of surgery. Patients were followed and data collected comprising demographics and AVF maturation. A fistula was considered mature when it was successfully accessed for hemodialysis (HD) at least three times. Statistical analysis was performed including receiver operating characteristics (ROC), ANOVA, and Chi square using the JMP software package. During the 12-month period, 70 autologous AVFs were created including 41 antecubital brachiocephalic, 21 radiocephalic, and 8 basilic vein transpositions in 35 females and 33 males with a mean age of 58+/-1.7 (mean+/-SEM). The group included 37 Hispanic, 17 Native American, 10 Caucasian, 3 African American and 1 Asian patient. The etiology of renal failure comprised 53 diabetics, 13 hypertensives, 1 polycystic kidney disease and 1 congenital abnormality. Complete follow-up was available in 69/70 AVFs in 67 patients. Patients were excluded from analysis if they had not yet started dialysis (n=12), stopped or died (n=4) before their fistula was accessed. Patients whose AVFs were patent, but required a secondary procedure to achieve a functional access were considered non-functional. There was a significant difference between the maximal intraoperative flow rates between functional and non-functional AVFs (573.6+/-103 mL/min vs. 216.8+/-35.8 mL/min; p<0.05). There was no difference between groups in regard to age, gender, race or etiology of renal failure. ROC analysis suggested a threshold value of 140 mL/min for radiocephalic and 308 mL/min for brachiocephalic AVFs to predict maturation to a functional access. Intraoperative blood flow measurements obtained at the time of autologous AVF construction can identify fistulas that are unlikely to mature; and therefore, that require immediate revision or abandonment which will ultimately expedite the establishment of a useful access in the HD patient. This is the first study to establish the minimal flow values uniquely needed for both radial artery and brachial artery AVFs to expect primary maturation to a functional access.

The Utility of Aortic Blood Flow Measurements in the Prediction of Pulmonary Artery Banding Outcome

The purpose of this study was to evaluate the clinical utility of intraoperative aortic blood flow measurements on clinical outcome in patients undergoing pulmonary artery banding (PAB). We reviewed 12 patients who underwent a PAB between September 2008 and March 2013 who also had intraoperative aortic blood flow measurements. Diagnosis included biventricular physiology in 6, single-ventricle physiology in 4, and inadequate systemic ventricle in 2 patients. Aortic blood flow was measured at the time of surgery by Transonic flow probe (Transonic Systems Inc, Ithaca, NY). Aortic flow, intraoperative hemodynamics, and clinical outcomes were analyzed to determine the potential predictive utility of intraoperative variables on postoperative outcomes. The aortic flow increased after PAB from 1.56 ± 0.73 to 2.20 ± 1.10 L · min(-1) · m(-2) (41.0% increase; p= 0.001). The efficacy of the PAB procedure was found to bedirectly related to the percentage increase in aortic blood flow measured intraoperatively. Three patients with lessthan 20% increase in aortic blood flow died, required re-PAB, or developed ventricular dysfunction, while patients with successful PAB had more than 40% increase in aortic blood flow. The percentage increase inaortic blood flow was not predictable based on pre-band or post-band absolute aortic blood flow measurements. Thepercentage increase in aortic blood flow was inversely correlated to the tightness of the PAB as defined relative to that predicted by the Trusler formula (r= 0.67; p= 0.01). This study identifies the change in the aortic blood flow as a new, physiologically based parameter to help predict PAB outcome.

Clinical Significance of Pulsatile Index and Diastolic Blood Flow for Popliteal and Tibial Bypass Patency

Aim: To compare data from pulsatile index [PI) and diastolic blood flow [DF%) after local administration of prostaglandines in failed and patent infrainguinal autovenous bypasses for at least one year, as well as to compare the data obtained from the tibial and the popliteal [above and below knee) bypasses and to estimate its clinical significance for their patency. Patients and Methods: Prospectively for two-year period 107 patients with peripheral arterial occlusive disease, who were subjected to autovenous bypass below the inguinal ligament were included. Intraoperative flowmetry was performed with a VeriQ flowmeter and perivascular probes ‘Medi-Stim’ at the target artery underneath the distal anastomosis. The measurements were performed after bypass declamping and after intragraft prostaglandin infusion. Results: Intraoperative measurement of blood flow by means of transit time and prostaglandin application was performed in all 107 patients. There were no significant differences between tibial and popliteal bypasses after prostaglandin administration, which to determine their different patency. Patients with early bypass failure had no significant alteration in the estimated values after prostaglandin infusion. Pulsatile index over 2 by specificity 84% and DF% under 51% by specificity 73% after prostaglandins are considered unsatisfying. Conclusion: Prostaglandin application underneath the distal anastomosis results in arterial vasodilatation and is an indicator of the quality of the byass, the anastomoses and run-off arterial capacity. Being dependent on the resistance of the blood outflow, the PI and DF% are important factors for the bypass prognosis but it cannot be calculated as a certain prognostic factor.

A comparative assessment of maxillary perfusion between two different Le Fort I osteotomy techniques

Compromised maxillary perfusion following Le Fort I osteotomy is a potentially serious complication resulting in hard and/or soft tissue loss. The aim of this study was to compare the change in perfusion between two techniques of posterior maxillary disjunction by intraoperative measurement of maxillary gingival blood flow (GBF). Further, we sought to correlate the association of the movement of the maxilla and estimated blood loss as factors. The study population comprised 38 individuals, divided equally into two groups: a pterygoid disjunction group and a third molar socket disjunction group. GBF was measured using Doppler flowmetry. A P-value of <0.05 was considered significant. There was a significant drop in GBF in both groups. However, there was no significant difference between the groups based on magnitude of blood flow drop. Superior repositioning of the osteotomized maxilla caused the greatest drop in GBF, which was statistically significant. There was significantly less blood loss in the pterygoid disjunction group. In conclusion, Le Fort I osteotomy causes a significant decrease in GBF. The technique used for posterior maxillary disjunction does not influence the magnitude of drop in perfusion. There is a significant correlation of other factors such as the effect of superior repositioning of the maxilla and blood loss with the osteotomy techniques.

Intra-operative graft blood flow measurements for composite and sequential coronary artery bypass grafting.

Intraoperative assessment of coronary artery bypass grafts (CABG) anastomotic quality can be performed using transit-time flowmetry (TTF). The aim of this study was to compare on- versus off-pump coronary graft TTF and early postoperative outcomes. Between January 2009 and January 2010, 521 distal graft flows were assessed using TTF measurements in 253 consecutive patients undergoing primary isolated CABG surgery. Data were analyzed using multilevel models accounting for clustering among surgeons and grafts performed in the same patient. Mean age was 66 ± 10 years and 22% were female (n = 55) with 34% diabetics (n = 86) and 40% preoperative myocardial infarction (MI) (n = 101). The surgeries were performed off-pump in 67% (n = 170) with sequential vein grafts in 57% (n = 144) of patients. Off-pump patients had higher pre-operative left ventricular ejection fractions (LVEF), fewer urgent surgeries, fewer distal anastomoses, and fewer sequential vein grafts (all p<0.001). Intra-operative coronary graft TTF measurements were lower in sequential vein grafts performed off-pump versus on-pump. More patients in the on-pump group needed milrinone or dobutamine 24-48h postoperatively (p = 0.005). Independent predictors of lower TTF included female gender and off-pump surgery, whereas predictors of better TTF were preoperative MI, larger coronary diameter at the site of the distal anastomosis, and sequential vein grafting. Lower intra-operative TTF measurements were found in sequential vein grafts in off-pump CABG. However, off-pump patients experienced similar short-term outcomes compared to on-pump patients.

Intraoperative assessment of vascular access.

The intraoperative quality assessment of the arteriovenous fistula for hemodialysis is an essential process to limit early failure due to technical problems or inadequate vascular quality. This step is not clearly defined in the literature with no recommendations. We selected published articles related to the topic of intraoperative quality control of the vascular access for hemodialysis. The intraoperative blood flow measurement greater than 120 ml/min in autologous fistula and less than 320 ml/min in arteriovenous graft was described as predictive factors for early failure. The blood flow measurement should be performed after the confection of the anastomosis. When blood flow is limited, fistulography is an essential step to assess patency.

Evaluation of Vascular Activity in Otosclerosis by Laser Doppler Flowmetry

To evaluate vascular activity in ears with otosclerosis by intraoperative measurement of blood flow using laser Doppler flowmetry and to compare the data with densitometry on computed tomography (CT). Retrospective case series. University hospital. Thirty-nine ears from 33 patients who underwent surgery for otosclerosis. The subjects were divided into fenestral (29 ears) and retrofenestral (10 ears) groups based on CT findings. Ratios of bone density in the area anterior to the oval window (AOW) or the promontory (PT) near the round window niche to that of the basis labyrinthine otic capsule were calculated on CT images. Measurements of blood flow were performed with a laser Doppler flowmeter at the 2 corresponding areas evaluated by CT. Imaging and blood flow values. In both groups, relatively young subjects with high blood flow values in the AOW or PT had rather low ratios of bone density in the corresponding areas. In contrast, old subjects with low ratios of bone density showed low blood flow values in the same areas. In the retrofenestral group, subjects with high blood flow values in the PT showed low blood flow values in the AOW, but their ratios of bone density were similarly low in both areas. Blood flow varied and did not correlate with CT densitometry. Measurement of blood flow by laser Doppler flowmetry could yield useful information to evaluate the progress of vascular activity.

Evaluation of Vascular Activity in Otosclerosis by Laser‐Doppler Flowmetry: Comparison with CT Densitometry

Objectives: Evaluate vascular activity in ears with otosclerosis by intraoperative measurement of blood flow using laser-Doppler flowmetry, and compare the data with densitometry on computed tomography (CT). Methods: Thirty-nine ears from patients who underwent surgery for otosclerosis were assessed in the present study. The subjects were divided into the fenestral (29 ears) and the retrofenestral (10 ears) groups by CT. Ratios of bone density in the area anterior to the oval window (AOW) or the promontory (PT) near the round window niche to that of the basis labyrinthine otic capsule were calculated on CT images. Measurements of blood flow were performed with a laser-Doppler flowmeter at the two corresponding areas evaluated by CT. Results: In both groups, relatively young subjects with high blood flow values in the AOW or PT had rather low ratios of bone density in the corresponding areas. In contrast, old subjects with low ratios of bone density showed low blood flow values in the same areas. In the retrofenestral group, subjects with high blood flow values in the PT showed low blood flow values in the AOW, but their ratios of bone density were similarly low in both areas. Conclusions: Blood flow varied and did not correlate with CT densitometry. Measurement of blood flow by laser-Doppler flowmetry could yield useful information to evaluate the progress of vascular activity.