Occlusion Test Research Articles

Simulation of endothelium-dependent vasodilation in young male persons based on the parameters of body weight components

The aim of the work. To analyze the results of endothelium-dependent vasodilation of the brachial artery in persons with different content of body weight components and to develop models for predicting the response of endothelium-dependent vasodilation based on the parameters of body weight components. Materials and methods. In total, 31 young men were examined and divided into three groups depending on the total body fat value: 16 people (51.6 %) – group I, 11 people (35.5 %) – group II and 4 people (12.9 %) – group III. Determination of such parameters as body mass index (BMI, kg/m2), the percentage of total fat (TFP, %), the visceral fat content (VFC, units) and the content of free-fat mass (FFM,%) was performed using a bioimpedance analyzer TANITA BC-601. Endothelial regulation was assessed on the basis of vasomotor dilation of the brachial artery activity before and after the occlusion test using a four-channel rheograph ReoCom (XAI-MEDICA). Results. During the occlusion test, three types of endothelium-dependent vasodilation (EDVD) were identified in individuals exa­mined. 62.50 % of men in group I had a normoergic reaction of the brachial artery, 31.25 % had a hyperergic and 6.25 % had a hypoergic reaction. Among group II persons, a normoergic type of post-occlusive reaction was in 45.4 %, hyperergic – in 36.4 %, and hypoergic type – in 18.2 %. Regarding group III, 75 % of individuals had the hyperergic type of endothelium-dependent vasodilation, 25 % had the normoergic type, and no hypoergic type of reaction was observed at all. To determine the endothelial vasoregulatory function on the basis of correlation-regression analysis, models were constructed with coefficients of determination R2 of 0.277 (BMI), 0.126 (TFP), 0.189 (VFC) and 0.146 (FFM). The models themselves had the following form: between EDVD and BMI – y = -4.5297 + 0.865x; TFP – y = 10.7389 + 0.4x; VFC – y =13.8119 + 1.0041x; FFM – y = 52.7904 – 0.4464x. In addition, statistically significant correlations were found between them – from r = +0.335 to r = +0.526. Conclusions. The data obtained allow us to note that the functional state of the endothelium and its activity depends on the content of body weight components in the organism.

Predictive factors for bleeding carotid artery pseudoaneurysms in patients with previous radiations for head and neck cancers.

Bleeding from carotid artery pseudoaneurysms is an emergency condition with high morbidity and mortality. We aimed to identify risk factors predicting pseudoaneurysmal bleeding as the cause of profuse epistaxis in irradiated head and neck cancer patients with suspect carotid blowout or pseudoaneurysms. We retrospectively reviewed consecutive patients with history of radiation therapy for head and neck cancers and with nasal, oral or ear bleeding requiring in-patient treatment from hospital database. Pseudoaneurysms were subgrouped into internal carotid artery (ICA) pseudoaneurysms, and external carotid artery (ECA) pseudoaneurysms. The treatment outcomes were evaluated using 30-day mortality rate, recurrent bleeding, and cerebral infarction. There were 41 admissions for suspected carotid blowout or pseudoaneurysms from 1 July 2016 to 30 June 2020 with 17 bleeding pseudoaneurysms identified, including 11 internal carotid arteries (ICA) pseudoaneurysms and 6 external carotid arteries (ECA) pseudoaneurysms. Among ICA pseudoaneurysms, six patients passed Balloon occlusion test with embolization and parent artery occlusion (trapping) of ICA performed, and all ECA pseudoaneurysms were embolized with parent artery occlusion (trapping). Baseline hypertension and hypotension on arrival were predictive for pseudoaneurysmal bleeding. The degree of haemoglobin drop was not significantly different between pseudoaneurysmal bleeding and non-pseudoaneurysmal bleeding (2.1 ± 1.4g/dL vs. 1.6 ± 1.4g/dL, p=0.234). We identified baseline hypertension and hypotension on arrival as predictive factors for pseudoaneurysmal bleeding in patients with irradiated head and neck cancer. Presence of these risk factors should alert the clinicians to the possibility of carotid pseudoaneurysms.

Performance Assessment of a Commercial Continuous-Wave Near-Infrared Spectroscopy Tissue Oximeter for Suitability for Use in an International, Multi-Center Clinical Trial.

Despite the wide range of clinical and research applications, the reliability of the absolute oxygenation measurements of continuous wave near-infrared spectroscopy sensors is often questioned, partially due to issues of standardization. In this study, we have compared the performances of 13 units of a continuous wave near-infrared spectroscopy device (PortaMon, Artinis Medical Systems, NL) to test their suitability for being used in the HEMOCOVID-19 clinical trial in 10 medical centers around the world. Detailed phantom and in vivo tests were employed to measure the precision and reproducibility of measurements of local blood oxygen saturation and total hemoglobin concentration under different conditions: for different devices used, different operators, for probe repositioning over the same location, and over time (hours/days/months). We have detected systematic differences between devices when measuring phantoms (inter-device variability, <4%), which were larger than the intra-device variability (<1%). This intrinsic variability is in addition to the variability during in vivo measurements on the forearm muscle resulting from errors in probe positioning and intrinsic physiological noise (<9%), which was also larger than the inter-device differences (<3%) during the same test. Lastly, we have tested the reproducibility of the protocol of the HEMOCOVID-19 clinical trial; that is, forearm muscle oxygenation monitoring during vascular occlusion tests over days. Overall, our conclusion is that these devices can be used in multi-center trials but care must be taken to characterize, follow-up, and statistically account for inter-device variability.

Fitness Level- and Sex-Related Differences in Macrovascular and Microvascular Responses during Reactive Hyperemia.

Reactive hyperemia (RH) is widely used for the investigation of macrovascular (flow-mediated dilation, or FMD) and microvascular (near-infrared spectroscopy-vascular occlusion test, or NIRS-VOT) function. Mixed results have been reported on fitness level- and sex-related differences in FMD outcomes, and little is known about microvascular differences in untrained and chronically trained males and females. Fifteen chronically trained (CT: 8 males, 7 females) and 16 untrained (UT: 8 males, 8 females) individuals participated in this study. Aerobic fitness (V˙O2max) was assessed during a cycling incremental exercise test to volitional exhaustion. FMD and NIRS-VOT were performed simultaneously on the lower limb investigating superficial femoral artery and vastus lateralis muscle, respectively. %FMD was not different between groups (CT males, 4.62 ± 1.42; CT females, 4.15 ± 2.23; UT males, 5.10 ± 2.53; CT females, 3.20 ± 1.67). Peak blood flow showed greater values in CT versus UT (P ≤ 0.0001) and males versus females (P = 0.032). RH blood flow area under the curve was greater in CT versus UT (P = 0.001). At the microvascular level, desaturation and reperfusion rates were faster in CT versus UT (P = 0.018 and P = 0.013) and males versus females (P = 0.011 and P = 0.005). V˙O2max was significantly correlated with reperfusion rate (P = 0.0005) but not with %FMD. Whereas NIRS-VOT outcomes identified fitness- and sex-related differences in vascular responses, %FMD did not. However, when RH-related outcomes from the FMD analysis were considered, fitness- and/or sex-related differences were detected. These data highlight the importance of integrating FMD and NIRS-VOT outcomes for a more comprehensive evaluation of vascular function.

The adding value of fluid challenge and balloon occlusion tests in patients with atrial septal defect

Abstract Background Careful, step-wise assessment is required in all patients with an atrial septal defect (ASD) to exclude pre-existing pulmonary vascular disease or left ventricular disease. Fluid challenge test (FCT) and balloon occlusion testing (BOT) may unmask left ventricular disease and challenge the pulmonary circulation, but their complementary role in the evaluation of patients with “operable” ASD is not well established. Aim To evaluate the haemodynamic changes of the pulmonary circulation by FCT and BOT in ASD patients undergoing percutaneous closure according to the current guidelines. Methods Consecutive patients selected for percutaneous ASD closure underwent invasive hemodynamic assessment at baseline and after BOT, FCT and both. Results Fifty patients (mean age 47.3±11.7 years, 72% female) were included. All patients had a pulmonary-to-systemic flow ratio (QP/QS) ≥1.5, pulmonary vascular resistance (PVR) &amp;lt;5 WU and pulmonary arterial wedge pressure (PAWP) &amp;lt;15 mmHg. Individuals with a PVR ≥2 WU at baseline were older, more symptomatic, with a higher baseline systemic vascular resistance compared to the lower PVR group (PVR &amp;lt;2 WU; p&amp;lt;0.0001). The response of Qp/Qs to FCT was different between groups (p&amp;lt;0.0001, Figure 1). Patients with a lower baseline PVR experienced an increase in Qp/Qs, which remained above 1.5 in all patients, whereas in almost all (90%) patients with a higher baseline PVR, the Qp/Qs fell to below 1.5. FCT caused a marked increase in pulmonary blood flow of almost 2 liters (p&amp;lt;0.0001) accompanied by increases in PAWP (p&amp;lt;0.0001). BOT led to a modest increase in PAWP (Δ1.5 [−1.0–7.0] mmHg, p&amp;lt;0.0001). FCT added to BOT caused a further increase in PAWP and Qs (both p&amp;lt;0.0001), while PVR was unchanged (p&amp;gt;0.1). No difference was observed in the PAWP response to FCT, BOT or both between groups; no patients reached a PAWP ≥18 mmHg following FCT or BOT alone, but 4 (8%) patients did following the addition of FCT to BOT. No acute clinical adverse events were experienced by any patients. Conclusions None of the reported ASD patients presented with FCT criteria of post-capillary PH (that is a PAWP &amp;gt;18 mmHg). Even small rises in PVR may have significant implications on cardiovascular haemodynamics. In fact, patients with PVR &amp;lt;2 WU showed an increase in Qp/Qs, which remained above 1.5 in all patients, suggesting that they still had a distensible pulmonary circulation, whereas in almost all patients with a PVR ≥2 WU, the Qp/Qs fell to below 1.5. Funding Acknowledgement Type of funding sources: None. Figure 1

Fluid responsiveness in patients under mechanical ventilation and low tidal volume ventilation through the pulse pressure variation after tidal volume challenge in the post-operative cardiac surgery

Abstract Background It is known that in the immediate postoperative period of cardiac surgery, strict control of hemodynamic variables and blood volume is necessary, since there is an imbalance between oxygen supply and consumption. Thus, the present study seeks to validate methods previously used in different clinical situations to predict fluid responsiveness, in the current scenario of the immediate postoperative period of cardiac surgery. Purpose To evaluate the influence of “tidal volume challenge” from 6 ml / kg to 8 ml / kg of the predicted body weight (PBW) in conjunction with the end expiratory occlusion test (EEOT) in the variation of pulse pressure to predict fluid responsiveness in the immediate postoperative period of cardiac surgery. Methodology This prospective study included 30 patients after cardiac surgery. Hemodynamic and ventilatory parameters were initially recorded in mechanical ventilation at 6 ml/kg and after tidial volume challenge and with the EEOT at 8 ml/kg of predicted body weight (PBW). After recorded the intervention data, there was a return to ventilation at 6 ml/kg and a saline infusion of 500 ml was performed for 15 minutes. Fluid responsiveness was defined for patients who had an increase of 10% or more in velocity time integral (VTI) by echocardiogram after volume expansion compared to baseline value. Multivariate analysis was used to identify independent predictors of fluid response status. Sensitivity and specificity analyzes were performed to determine the predictive precision of each parameter. Results The main result of our study is that, when the tidal volume is increased from 6 to 8 ml/kg of PBW, the relative increase in pulse pressure variation (%ΔPPV6–8) predicts with excellent accuracy responsiveness to fluids with cut-off values of 18.3%, with sensitivity of 92.9% and specificity of 84% (P=0.019). Although changing PPV6, EEOT6 and EEOT8 are not reliable in predicting fluid responsiveness, they still require additional calculations. PPV8 also discriminates between responders and non-responders; however, with sensitivity (78.6%) and specificity (66.6%) when the value found in the PPV8 is up 8.5, but without statistical significance (figure). Conclusion The challenge of tidal volume and its influence on the ΔPP variation has excellent accuracy to predict fluid responsiveness in the immediate postoperative period of cardiac surgery. EEOT did not present good accuracy to predict fluid responsiveness in patients in the immediate postoperative period of cardiac surgery. Funding Acknowledgement Type of funding sources: None.

Effects of methylene blue on microcirculatory alterations following cardiac surgery: A prospective cohort study.

Methylene blue is used as rescue therapy to treat catecholamine-refractory vasoplegic syndrome after cardiac surgery. However, its microcirculatory effects remain poorly documented. We aimed to study microcirculatory abnormalities in refractory vasoplegic syndrome following cardiac surgery with cardiopulmonary bypass and assess the effects of methylene blue. A prospective open-label cohort study. 20-Bed ICU of a tertiary care hospital. 25 Adult patients receiving 1.5 mg kg-1 of methylene blue intravenously for refractory vasoplegic syndrome (defined as norepinephrine requirement more than 0.5 μg kg-1 min-1) to maintain mean arterial pressure (MAP) more than 65 mmHg and cardiac index (CI) more than 2.0 l min-1 m-2. Complete haemodynamic set of measurements at baseline and 1 h after the administration of methylene blue. Sublingual microcirculation was investigated by sidestream dark field imaging to obtain microvascular flow index (MFI), total vessel density, perfused vessel density and heterogeneity index. Microvascular reactivity was assessed by peripheral near-infrared (IR) spectroscopy combined with a vascular occlusion test. We also performed a standardised measurement of capillary refill time. Despite normalised CI (2.6 [2.0 to 3.8] l min-1 m-2) and MAP (66 [55 to 76] mmHg), patients with refractory vasoplegic syndrome showed severe microcirculatory alterations (MFI < 2.6). After methylene blue infusion, MFI significantly increased from 2.0 [0.1 to 2.5] to 2.2 [0.2 to 2.8] (P = 0.008), as did total vessel density from 13.5 [8.3 to 18.5] to 14.9 [10.1 to 14.7] mm mm-2 (P = 0.02) and perfused vessel density density from 7.4 [0.1 to 11.5] to 9.1 [0 to 20.1] mm mm-2 (P = 0.02), but with wide individual variation. Microvascular reactivity assessed by tissue oxygen resaturation speed also increased from 0.5 [0.1 to 1.8] to 0.7 [0.1 to 2.7]% s-1 (P = 0.002). Capillary refill time remained unchanged throughout the study. In refractory vasoplegic syndrome following cardiac surgery, we found microcirculatory alterations despite normalised CI and MAP. The administration of methylene blue could improve microvascular perfusion and reactivity, and partially restore the loss of haemodynamic coherence. ClinicalTrials.gov identifier: NCT04250389.

頭蓋底骨折後遅発性に鼻出血を契機に発見された内頸動脈仮性瘤の1例(A case of delayed discovery of a internal carotid artery pseudoaneurysm by nosebleeds after skull base fracture)

要旨 頭部外傷に伴う頭蓋底骨折はときに仮性動脈瘤を合併する。今回我々は，頭蓋底骨折後受傷時に損傷を認めなかった右内頸動脈に遅発性に仮性動脈瘤を形成した1例を経験したので報告する。症例は74歳の男性。約3mの高さから墜落し顔面を強打した。救急隊接触時，外表上頭部・顔面に外傷を認め，発語不能であったため，重症頭部外傷が疑われ当院へ搬送された。来院時CT検査において右視神経損傷を伴う頭蓋底骨折，脳挫傷，外傷性くも膜下出血，右肩甲骨骨折，多発肋骨骨折を認めたが，仮性動脈瘤は認めなかった。上記各外傷に対し保存的加療を行い，第19病日軽快転医となった。第38病日初回の鼻出血を認めた。第47病日中等量の鼻出血を認め，鼻腔内ガーゼ充填で止血を得た。第79病日より隔日で鼻出血を認めるようになったが，耳鼻科診察では鼻粘膜に特記すべき異常を認めなかった。第84病日多量の鼻出血と血圧低下，冷汗を認め，造影CTで右内頸動脈に仮性動脈瘤を認めたため，当院へ再度転医となった。第85病日右浅側頭動脈–中大脳動脈吻合術および右内頸動脈瘤コイル塞栓術を行い，第90病日MRAで瘤への血流がないことを確認した。第96病日に転医し，第106病日独歩退院となった。本症例では頭部外傷後の鼻出血により，仮性動脈瘤を発見し得た。頭蓋底骨折後の血管評価は受傷時に損傷を認めなくても継時的な画像評価などを慎重に行う必要がある。

Measurement of capillary refill time with a handheld prototype device: a comparative validation study in healthy volunteers.

Validity and reproducibility of clinical capillary refill time (CRT) measurement depend on many factors in daily routine practice. We conducted a prospective validation study of an automatized handheld prototype device providing standardized CRT assessment (DiCART™) in 20 healthy volunteers. Three different methods of CRT measurement were compared before and during dynamic circulatory changes induced by venous and arterial occlusion tests at both upper and lower limb levels: CRTCLIN corresponding to basic clinical assessment and considered as the reference method; CRTVIDEO corresponding to off-line videos reviewed by investigators recorded by DiCART™; and CRTDiCART corresponding to on-line videos analysed by a built-in proprietary mathematical algorithm included in DiCART™. Five subjects were excluded because of a DiCART™ dysfunction. ROCAUC to detect arterial occlusion test changes at the upper limb level were 1.00 (95%CI 1.00; 1.00), 0.96 (95%CI 0.88; 1.00), and 0.92 (95%CI 0.79; 1.00) for CRTCLIN, CRTVIDEO, and CRTDiCART, respectively. Precision of CRTCLIN and CRTVIDEO were significantly better than CRTDiCART (0.18 and 0.20 vs. 0.28; P < 0.05). Percentages of error were 76% and 87% for CRTVIDEO and CRTDiCART, respectively. DiCART™ had an excellent discrimination to detect major changes in CRT induced by arterial ischemia. However, the perfectible precision, the poor agreement with clinical assessment and numerous device dysfunctions give leads to the development of a further version of the prototype before promoting its use in clinical practice.Trial registration clinicaltrial.gov. Identifier: NCT04538612.

Ciphertext-only attacks on the double random phase encryption based on redundancy vulnerability

The double random phase encoding techniques have received considerable attention from researchers in recent years because of their advantages of parallel and high-speed processing capability. Meanwhile, the security of the cryptosystem is also one of the major concerns. We experimentally showed the ciphertext redundancy vulnerability of the coherent double random phase encryption (DRPE) system. Based on the statistical ergodicity of speckles and the consistency of the energy spectral density (ESD), we have proved that the method can retrieve the most plaintext information from partial ciphertext alone. We performed the simulation and experimental results to verify whether the algorithm is effective. The ciphertext redundancy of the DRPE system is analyzed from the results of the ciphertext occlusion test. There is a risk of plaintext leakage in this scheme, as long as the average ESD can be estimated from the sub-images. The results will further our understanding of the limitation of current optical security techniques. The DRPE system has potential redundancy risk. This vulnerability allows a cryptanalyst to estimate the plaintext information with only a half or less ciphertext.

Novel method of transpulmonary pressure measurement with an air-filled esophageal catheter

BackgroundThere is a strong rationale for proposing transpulmonary pressure-guided protective ventilation in acute respiratory distress syndrome. The reference esophageal balloon catheter method requires complex in vivo calibration, expertise and specific material order. A simple, inexpensive, accurate and reproducible method of measuring esophageal pressure would greatly facilitate the measure of transpulmonary pressure to individualize protective ventilation in the intensive care unit.ResultsWe propose an air-filled esophageal catheter method without balloon, using a disposable catheter that allows reproducible esophageal pressure measurements. We use a 49-cm-long 10 Fr thin suction catheter, positioned in the lower-third of the esophagus and connected to an air-filled disposable blood pressure transducer bound to the monitor and pressurized by an air-filled infusion bag. Only simple calibration by zeroing the transducer to atmospheric pressure and unit conversion from mmHg to cmH2O are required. We compared our method with the reference balloon catheter both ex vivo, using pressure chambers, and in vivo, in 15 consecutive mechanically ventilated patients. Esophageal-to-airway pressure change ratios during the dynamic occlusion test were close to one (1.03 ± 0.19 and 1.00 ± 0.16 in the controlled and assisted modes, respectively), validating the proper esophageal positioning. The Bland–Altman analysis revealed no bias of our method compared with the reference and good precision for inspiratory, expiratory and delta esophageal pressure measurements in both the controlled (largest bias −0.5 cmH2O [95% confidence interval: −0.9; −0.1] cmH2O; largest limits of agreement −3.5 to 2.5 cmH2O) and assisted modes (largest bias −0.3 [−2.6; 2.0] cmH2O). We observed a good repeatability (intra-observer, intraclass correlation coefficient, ICC: 0.89 [0.79; 0.96]) and reproducibility (inter-observer ICC: 0.89 [0.76; 0.96]) of esophageal measurements. The direct comparison with pleural pressure in two patients and spectral analysis by Fourier transform confirmed the reliability of the air-filled catheter-derived esophageal pressure as an accurate surrogate of pleural pressure. A calculator for transpulmonary pressures is available online.ConclusionsWe propose a simple, minimally invasive, inexpensive and reproducible method for esophageal pressure monitoring with an air-filled esophageal catheter without balloon. It holds the promise of widespread bedside use of transpulmonary pressure-guided protective ventilation in ICU patients.

Cervical to Petrous Carotid Artery High-Flow Bypass for Carotid Artery Pseudoaneurysm Through Zygomatic Approach: 2-Dimensional Operative Video

Pseudoaneurysms of the cervical internal carotid artery may generate grave risk from catastrophic rupture, thromboembolic stroke, or mass effect. They have many causes, including malignancy, infection, and iatrogenic and most commonly blunt or penetrating trauma.1 These aneurysms require treatment to eliminate their risk. Treatment options include trapping, with or without revascularization, or endovascular stenting. Trapping without revascularization requires evaluation of the cerebral collateral under a physiological challenge, which is usually done with a balloon occlusion test, which is not applicable in this lesion.2 Occluding the carotid without revascularization carries the risk of delayed ischemia and aneurysm formation.3,4 Carotid stenting has been applied in the treatment of these lesions5,6; however, the extent of the lesion in our patient from the carotid bifurcation to the petrous carotid makes endovascular treatment challenging. We present a patient with a delayed post-traumatic pseudoaneurysm of the carotid artery that extended from the bifurcation to the petrous carotid who was treated with trapping and high-flow saphenous vein bypass from the proximal cervical internal carotid to the petrous carotid. Adequate exposure of the petrous carotid to perform anastomosis requires a thorough knowledge of the anatomy and surgical nuances, which we demonstrate here through a zygomatic approach.7 The patient consented to the procedure and publication of imaging. Image at 2:28 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997, with permission.

Men exhibit faster skeletal muscle tissue desaturation than women before and after a fatiguing handgrip.

PurposeThe purpose was to test the hypothesis that sex and fatigue effect of the early phase of skeletal muscle tissue oxygenation (StO2, %) desaturation rate as well as that strength matched adults may exhibit similar responses.MethodsTwenty-four adults visited the laboratory twice to quantify this early phase of desaturation during vascular occlusion tests (VOT) while in a rested state. The second visit included a sustained handgrip task at 25% of maximal muscular strength until task failure. At failure, a post-task VOT was initiated. Muscle desaturation was defined as StO2 and collected by a near-infrared spectroscopy device. The muscle size and adipose thickness were determined via ultrasonography. Linear regression was used to quantify the rates of desaturation during the VOTs as well as during the fatiguing handgrip.ResultsThere were sex differences in the rate of desaturation pre- and post-handgrip, such that independent of fatigue, the men (p < 0.001) desaturated more rapidly than the women (pre: b = − 0.208 vs. − 0.123%∙s−1; post: − 0.079 vs. − 0.070%∙s−1). During the fatiguing handgrip, the transformed StO2 values indicated that the males desaturated more rapidly than the females (b = − 0.070 vs. − 0.015). The matched pairs exhibited the same responses as the total sample.ConclusionOverall, muscle size and strength as well as adipose tissue were likely not the primary cause of the differences in rates of muscle desaturation. We hypothesized that differences in fiber type and mitochondria were the principle mechanisms provoking the differences in muscle oxygenation.

Effect of curvature correction on parameters extracted from hyperspectral images.

.Significance: Hyperspectral imaging (HSI) has emerged as a promising optical technique. Besides optical properties of a sample, other sample physical properties also affect the recorded images. They are significantly affected by the sample curvature and sample surface to camera distance. A correction method to reduce the artifacts is necessary to reliably extract sample properties.Aim: Our aim is to correct hyperspectral images using the three-dimensional (3D) surface data and assess how the correction affects the extracted sample properties.Approach: We propose the combination of HSI and 3D profilometry to correct the images using the Lambert cosine law. The feasibility of the correction method is presented first on hemispherical tissue phantoms and next on human hands before, during, and after the vascular occlusion test (VOT).Results: Seven different phantoms with known optical properties were created and imaged with a hyperspectral system. The correction method worked up to 60 deg inclination angle, whereas for uncorrected images the maximum angles were 20 deg. Imaging hands before, during, and after VOT shows good agreement between the expected and extracted skin physiological parameters.Conclusions: The correction method was successfully applied on the images of tissue phantoms of known optical properties and geometry and VOT. The proposed method could be applied to any reflectance optical imaging technique and should be used whenever the sample parameters need to be extracted from a curved surface sample.

Microcirculation Disorders in Patients with Severe COVID-19

Impaired microcirculation due to endothelial dysfunction in COVID-19 is considered to be the most important link in the pathogenesis of this disease. However, due to the complexity of its instrumental assessment in critically ill patients, the data available in the literature on specific manifestations of endothelial dysfunction are very contradictory.The objective: to determine the most characteristic capillaroscopic signs of microvascular disorders and to assess the state of microcirculation regulation in patients with severe COVID-19.Subjects and Methods. When admitted to the intensive care unit, 60 patients with COVID-19 and 12 patients with chronic cardiovascular pathology without COVID-19 (Comparison Group) were examined. All patients underwent microscopy of the microcirculatory bed of finger nail bed; the following parameters were assessed: diameters of the venous, arterial and transitional parts of capillaries, height of capillary loops, density of capillaries per 1 mm of the length of the perivascular zone, the average linear velocity of capillary blood flow (LVCBF), and thickness of the perivascular zone. The presence of avascular zones, the number of capillaries in the visualized field with circulating aggregates in the lumen, and the shape of capillaries were taken into account. In addition, an occlusion test using laser Doppler flowmetry was performed in 32 patients with COVID-19. The maximum post-occlusive increase in blood flow at the moment of cuff deflation was assessed, as well as changes in the mean value of post-occlusive blood flow relative to the baseline within 3 minutes after cuff deflation.Results. In 53 (88.3%) patients with COVID-19, abnormalities corresponding to chronic microcirculatory changes in the form of predominance of pathological capillary forms were detected. Microaggregates in the lumen of capillaries and decreased linear velocity of blood flow were revealed in 100% of cases. When comparing groups of patients with different outcomes, statistically significant differences were revealed between the LVCBF parameters (in the survivors - 354.35 ± 44.78 pm/sec, in the deceased - 278.4 ± 26.59 pm/sec), as well as between the values of the perivascular zones thickness (95.35 ± 15.96 microns versus 159.93 ± 19.90 microns). The results of the post-occlusion test revealed a significant difference between the groups in terms of the maximum post-occlusion gain (39.42 ± 3.85 BPU in the group with a favorable outcome, 27.69 ± 3.19 BPU in the group with an unfavorable outcome, 47.23 ± 1.78 BPU in the control group). In both groups, there was no increase in this parameter relative to the initial blood flow. At the same time, in the control group, the average index of post-occlusive blood flow was higher than the initial level.Conclusions. Acute microcirculation disorders with decreased linear velocity of capillary blood flow, circulation of aggregates, increased thickness of the perivascular zone were detected in all patients with severe COVID-19 but especially in those with unfavorable outcomes. Vascular tone regulation disorders were manifested by the absence of reactive hyperemia in response to acute ischemia, as well as a decrease in maximal flow-induced increase. These changes fit into the concept of endothelial dysfunction. Signs of chronic microcirculation disorders in most patients increase the risk of severe COVID-19.

Bioreactance reliably detects preload responsiveness by the end-expiratory occlusion test when averaging and refresh times are shortened

BackgroundThe end-expiratory occlusion (EEXPO) test detects preload responsiveness, but it is 15 s long and induces small changes in cardiac index (CI). It is doubtful whether the Starling bioreactance device, which averages CI over 24 s and refreshes the displayed value every 4 s (Starling-24.4), can detect the EEXPO-induced changes in CI (ΔCI). Our primary goal was to test whether this Starling device version detects preload responsiveness through EEXPO. We also tested whether shortening the averaging and refresh times to 8 s and one second, respectively, (Starling-8.1) improves the accuracy of the device in detecting preload responsiveness using EEXPO.MethodsIn 42 mechanically ventilated patients, during a 15-s EEXPO, we measured ∆CI through calibrated pulse contour analysis (CIpulse, PiCCO2 device) and using the Starling device. For the latter, we considered both CIStarling-24.4 from the commercial version and CIStarling-8.1 derived from the raw data. For relative ∆CIStarling-24.4 and ∆CIStarling-8.1 during EEXPO, we calculated the area under the receiver operating characteristic curve (AUROC) to detect preload responsiveness, defined as an increase in CIpulse ≥ 10% during passive leg raising (PLR). For both methods, the correlation coefficient vs. ∆CIpulse was calculated.ResultsTwenty-six patients were preload responders and sixteen non preload-responders. The AUROC for ∆CIStarling-24.4 was significantly lower compared to ∆CIStarling-8.1 (0.680 ± 0.086 vs. 0.899 ± 0.049, respectively; p = 0.027). A significant correlation was observed between ∆CIStarling-8.1 and ∆CIpulse (r = 0.42; p = 0.009), but not between ∆CIStarling-24.4 and ∆CIpulse. During PLR, both ∆CIStarling-24.4 and ∆CIStarling-8.1 reliably detected preload responsiveness.ConclusionsShortening the averaging and refresh times of the bioreactance signal to 8 s and one second, respectively, increases the reliability of the Starling device in detection of EEXPO-induced ∆CI.Trial registration: No. IDRCB:2018-A02825-50. Registered 13 December 2018.

Efficacies of preoperative prism adaptation test and monocular occlusion for detecting the maximum angle of deviation in intermittent exotropia

BackgroundThe efficacies of prism adaptation test (PAT) and monocular occlusion (MO) and their optimal test durations to detect the maximum angles of deviation at near and distance in eyes with intermittent exotropia (IXT) were assessed and compared.MethodsWe retrospectively reviewed the medical records of 72 patients with IXT. All the patients had undergone the initial strabismus surgery between April 2015 and October 2018 and had been preoperatively tested by both PAT and MO performed on different days for 30 and 60 min. Near and distance deviations after 30 and 60 min of PAT and MO were compared to their baseline measurements obtained immediately after prism wear and before occlusion by alternate prism cover test. The near/distance measurements and required test duration to reveal the maximum deviation angle were also compared between PAT and MO.ResultsCompared with the baseline, the near deviation by PAT significantly increased after 30 (P < 0.05) and 60 (P < 0.01) minutes but not the distance deviation. However, the increase after 30 min was not significant. By MO, neither near nor distance deviation showed a significant difference from the baseline after 30 and 60 min. PAT showed a significantly larger near deviation than MO at 30 and 60 min, but a larger distance deviation by PAT was only observed at 30 min.ConclusionsIn patients with basic and convergence insufficiency types of IXT, a 30-minute PAT appears to be more effective than MO in revealing the maximum angle of deviation before strabismus surgery.

Changes in peripheral perfusion index during intraoperative end-expiratory occlusion tests do not predict the response to fluid administration in patients undergoing lung protective ventilation.

The end-expiratory occlusion test (EEOT) may predict the response to fluid administration in patients undergoing lung-protective ventilation, but arterial catheter insertion is necessary to evaluate changes in stroke volume (SV). The peripheral perfusion index is a potential noninvasive alternative to evaluate SV. The aim of this study is to investigate whether changes in perfusion index during an intraoperative EEOT can predict the response to fluid administration in patients undergoing lung-protective ventilation (tidal volume 7ml/kg predicted body weight). Forty-one elective surgical patients were enrolled. The SV and perfusion index were recorded before (baseline), during a 40-s EEOT and after volume expansion (250ml of lactated Ringer's solution over 10min). Patients with an increase in SV greater than 10% after volume expansion were defined as responders. ΔPI (change in perfusion index between baseline and 20 (ΔPI20) or 40s (ΔPI40) after the beginning of EEOT were calculated using: ΔPI20 (%) = [(PI at 20s after EEOT beginning-PIbaseline)/PIbaseline] × 100, ΔPI40 (%) = [(PI at 40s after EEO beginning-PIbaseline)/PIbaseline] × 100). Sixteen patients were responders, and 25 were non-responders. The area under the receiver operating characteristics curves generated for ΔPI20 and ΔPI40 to predict response to a fluid challenge were 0.561 (95% CI 0.374-0.749) and 0.688 (95% CI 0.523-0.852), respectively. Changes in perfusion index during intraoperative EEOT in patients undergoing lung-protective ventilation (7ml/kg) were unable to predict the response to fluid administration.

Fluid challenge and balloon occlusion testing in patients with atrial septal defects

IntroductionCareful, stepwise assessment is required in all patients with atrial septal defect (ASD) to exclude pulmonary vascular or left ventricular (LV) disease. Fluid challenge and balloon occlusion may unmask LV...

No Need for Reconstruction of a Giant Aortic Aneurysm in an Infant

A female neonate (40 weeks; 3 290 g weight) was diagnosed with an abdominal aortic aneurysm (3.3 cm × 2.9 cm) and asymptomatic thrombosis of the left common iliac artery, confirmed by magnetic resonance imaging and computed tomography at birth (A, arrow). Because of the difficulty of aorto-iliac reconstruction, progressive expansion and the extensive collateral network at nine months old, the infrarenal aorta (B, arrow) and right common iliac artery were ligated, after a one hour occlusion test with perfusion monitoring of the lower extremities and intestines. The post-operative period was uneventful and at 12 months the child remains asymptomatic.