Trimetazidine improves angiogenesis and tissue perfusion in ischemic rat skeletal muscle.

Introduction: Peripheral artery disease (PAD) is an increasingly common disease, causing significant complications for patients. Trimetazidine (TMZ) not only improves clinical symptoms in PAD patients but also facilitates angiogenesis in ischemic hind limbs. Our aim was to find the function of TMZ in promoting angiogenesis and tissue perfusion in ischemic rat skeletal muscle. Methods: The rats underwent femoral artery ligation (FAL) and then treated with TMZ and saline. Hematoxylin-eosin and Masson's trichrome stain in the ischemic gastrocnemius muscle to analyze muscle morphology and atrophy. To identify angiogenesis and the tissue perfusion, CD31 immunohistochemical staining and laser speckle contrast imaging was conducted. Additionally, hind limb motor ability was measured. Finally, qRT-PCR and Western blotting were used to statistically analyze the expression levels of HIF-1α and VEGF. Results: Our study demonstrated significant enhancement in angiogenesis and tissue perfusion after FAL when treated with TMZ compared to the saline group. Histologically, it mitigates ischemia-induced muscle atrophy and inflammation, as well as reduces fibrosis progression in the TMZ group. Additionally, hind limb motor ability improved in rats treated with TMZ during motor experiments. Discussion: It suggests that TMZ can promote angiogenesis and improve tissue perfusion in ischemic skeletal muscle of rats by activating the HIF-1α/VEGF signaling pathway. Additionally, it leads to significant improvement in ischemia-induced motor limitations in the hind limbs of rats.

The physiological basis for individualized oxygenation targets in critically ill patients with circulatory shock.

BACKGROUND: Circulatory shock, defined as decreased tissue perfusion, leading to inadequate oxygen delivery to meet cellular metabolic demands, remains a common condition with high morbidity and mortality. Rapid restitution and restoration of adequate tissue perfusion are the main treatment goals. To achieve this, current hemodynamic strategies focus on adjusting global physiological variables such as cardiac output (CO), hemoglobin (Hb) concentration, and arterial hemoglobin oxygen saturation (SaO2). However, it remains a challenge to identify optimal targets for these global variables that best support microcirculatory function. Weighting up the risks and benefits is especially difficult for choosing the amount of oxygen supplementation in critically ill patients. This review assesses the physiological basis for oxygen delivery to the tissue and provides an overview of the relevant literature to emphasize the importance of considering risks and benefits and support decision making at the bedside. PHYSIOLOGICAL PREMISES: Oxygen must reach the tissue to enable oxidative phosphorylation. The human body timely detects hypoxia via different mechanisms aiming to maintain adequate tissue oxygenation. In contrast to the pulmonary circulation, where the main response to hypoxia is arteriolar vasoconstriction, the regulatory mechanisms of the systemic circulation aim to optimize oxygen availability in the tissues. This is achieved by increasing the capillary density in the microcirculation and the capillary hematocrit thereby increasing the capacity of oxygen diffusion from the red blood cells to the tissue. Hyperoxia, on the other hand, is associated with oxygen radical production, promoting cell death. CURRENT STATE OF RESEARCH: Clinical trials in critically ill patients have primarily focused on comparing macrocirculatory endpoints and outcomes based on stroke volume and oxygenation targets. Some earlier studies have indicated potential benefits of conservative oxygenation. Recent trials show contradictory results regarding mortality, organ dysfunction, and ventilatory-free days. Empirical studies comparing various targets for SaO2, or partial pressure of oxygen indicate a U-shaped curve balancing positive and negative effects of oxygen supplementation. CONCLUSION AND FUTURE DIRECTIONS: To optimize risk-benefit ratio of resuscitation measures in critically ill patients with circulatory shock in addition to individual targets for CO and Hb concentration, a primary aim should be to restore tissue perfusion and avoid hyperoxia. In the future, an individualized approach with microcirculatory targets will become increasingly relevant. Further studies are needed to define optimal targets.

Clinical Consensus Statement on the Use of Indocyanine Green Fluorescence-guided Surgery in Pediatric Patients.

BACKGROUND AND AIMS: Indocyanine Green Fluorescence (ICG-F)- guided surgery is becoming an increasingly helpful tool in pediatric surgical care. This consensus statement investigates the utility of ICG-F in various pediatric surgical applications, primarily focusing on its evidence base, safety, indications, use across different surgical specialties and dosing strategies. The aim is to establish an international consensus for ICG-F use in pediatric surgery. METHODS: An international panel of 15 pediatric surgeons from 9 countries was assembled. The structured process consisted of a rapid scoping review, iterative discussion sessions, mixed-methods studies with key stakeholders, and voting rounds on individual statements to create draft consensus statements. RESULTS: 100 articles were identified during the review and summarized by application. Based on this condensed evidence, consensus statements were generated after 3 iterative rounds of anonymous voting. Key areas of agreement were quality of evidence, the safety of ICG, pediatric surgical indications, utilization per surgical specialty, and dosing of ICG. CONCLUSION: This consensus statement aims to guide healthcare professionals in managing ICG-F use in pediatric surgical cases based on the best available evidence, key stakeholder consultation, and expert opinions. Despite ICG-F's promising potential, the need for higher-quality evidence, prospective trials, and safety studies is underscored. The consensus also provides a framework for pediatric surgeons to utilize ICG-F effectively. LEVEL OF EVIDENCE: III.

CO2 gap changes compared with cardiac output changes in response to intravenous volume expansion and/or vasopressor therapy in septic shock.

Background: The difference in partial pressure of carbon dioxide (PCO2) between mixed or central venous blood and arterial blood, known as the ∆PCO2 or CO2 gap, has demonstrated a strong relationship with cardiac index during septic shock resuscitation. Early monitoring of the ∆PCO2 can help assess the cardiac output (CO) adequacy for tissue perfusion. Objectives: To investigate the value of ∆PCO2 changes in early septic shock management compared with CO. Methods: This observational prospective study included 76 patients diagnosed with septic shock admitted to Cairo University Hospital's Critical Care Department between December 2020 and March 2022. Patients were categorised by initial resuscitation response, initial ∆PCO2 and 28-day mortality. The primary outcome was the relationship between the ∆PCO2 and CO changes before and after initial resuscitation, with secondary outcomes including ICU length of stay (LOS) and 28-day mortality. Results: Peri-resuscitation ∆PCO2 changes predicted a ≥15% change in the cardiac index (CI) (area under the curve (AUC) 0.727; 95% CI 0.614 - 0.840) with 66.7% sensitivity and 62.8% specificity. The optimal ∆PCO2 change cut-off value was <-1.85, corresponding to a <-22% threshold for a 15% cardiac index increase. The PCO2 gap ratio (gap/gap ratio of T1- PCO2 gap to T0 -PCO2 gap) also predicted a ≥15% change in cardiac index (AUC 745; 95% CI 0.634 - 0.855) with 63.6% sensitivity and 79.1% specificity. The optimal CO2 gap/gap ratio cut-off value was <0.71. A significant difference in 28-day mortality was noted based on the gap/gap ratio. Conclusion: Peri-resuscitation ∆PCO2 and the gap/gap ratio are useful non-invasive bedside markers for predicting changes in CO and preload responsiveness. Contribution of the study: The current study provides an insight to the PCO2 gap changes during and after early resuscitation of septic shock patients, which correlate to cardiac output changes and might also serve as a fluid responsiveness indicator.

Advancing DIEP Flap Monitoring with Optical Imaging Techniques: A Narrative Review.

OBJECTIVES: This review aims to explore recent advancements in optical imaging techniques for monitoring the viability of Deep Inferior Epigastric Perforator (DIEP) flap reconstruction. The objectives include highlighting the principles, applications, and clinical utility of optical imaging modalities such as near-infrared spectroscopy (NIRS), indocyanine green (ICG) fluorescence angiography, laser speckle contrast imaging (LSCI), hyperspectral imaging (HSI), dynamic infrared thermography (DIRT), and short-wave infrared thermography (SWIR) in assessing tissue perfusion and oxygenation. Additionally, this review aims to discuss the potential of these techniques in enhancing surgical outcomes by enabling timely intervention in cases of compromised flap perfusion. MATERIALS AND METHODS: A comprehensive literature review was conducted to identify studies focusing on optical imaging techniques for monitoring DIEP flap viability. We searched PubMed, MEDLINE, and relevant databases, including Google Scholar, Web of Science, Scopus, PsycINFO, IEEE Xplore, and ProQuest Dissertations & Theses, among others, using specific keywords related to optical imaging, DIEP flap reconstruction, tissue perfusion, and surgical outcomes. This extensive search ensured we gathered comprehensive data for our analysis. Articles discussing the principles, applications, and clinical use of NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR in DIEP flap monitoring were selected for inclusion. Data regarding the techniques' effectiveness, advantages, limitations, and potential impact on surgical decision-making were extracted and synthesized. RESULTS: Optical imaging modalities, including NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR offer a non- or minimal-invasive, real-time assessment of tissue perfusion and oxygenation in DIEP flap reconstruction. These techniques provide objective and quantitative data, enabling surgeons to monitor flap viability accurately. Studies have demonstrated the effectiveness of optical imaging in detecting compromised perfusion and facilitating timely intervention, thereby reducing the risk of flap complications such as partial or total loss. Furthermore, optical imaging modalities have shown promise in improving surgical outcomes by guiding intraoperative decision-making and optimizing patient care. CONCLUSIONS: Recent advancements in optical imaging techniques present valuable tools for monitoring the viability of DIEP flap reconstruction. NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR offer a non- or minimal-invasive, real-time assessment of tissue perfusion and oxygenation, enabling accurate evaluation of flap viability. These modalities have the potential to enhance surgical outcomes by facilitating timely intervention in cases of compromised perfusion, thereby reducing the risk of flap complications. Incorporating optical imaging into clinical practice can provide surgeons with objective and quantitative data, assisting in informed decision-making for optimal patient care in DIEP flap reconstruction surgeries.

The Role of the Tissue Perfusion Index in Predicting Disease Severity and Prognosis in Patients with Severe and Critical COVID-19.

OBJECTIVES: The study investigated whether percutaneous partial pressure of oxygen (PtcO2), percutaneous partial pressure of carbon dioxide (PtcCO2), and the derived tissue perfusion index (TPI) can predict the severity and short-term outcomes of severe and critical COVID-19. DESIGN: Prospective observational study conducted from January 1, 2023 to February 10, 2023. SETTING: A teaching hospital specializing in tertiary care in Nanjing City, Jiangsu Province, China. PARTICIPANTS: Adults (≥18 years) with severe and critical COVID-19. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The general information and vital signs of the patients were collected. The PtcO2 and PtcCO2 were monitored in the left dorsal volar. The ratio of TPI was defined as the ratio of PtcO2/fraction of inspired oxygen (FiO2) to PtcCO2. Mortality at 28 was recorded. The ability of the TPI to assess disease severity and predict prognosis was determined. ENDPOINT: Severity of the disease on the enrollment and mortality at 28. RESULTS: A total of 71 patients with severe and critical COVID-19, including 40 severe and 31 critical cases, according to the COVID-19 treatment guidelines published by WHO, were recruited. Their median age was 70 years, with 56 (79%) males. The median SpO2/FiO2, PtcO2, PtcCO2, PtcO2/ FiO2, and TPI values were 237, 61, 42, 143, and 3.6 mm Hg, respectively. Compared with those for severe COVID-19, the TPI, PtcO2/ FiO2, SpO2/FiO2, and PtcO2 were significantly lower in critical COVID-19, while the PtcCO2 was significantly higher. After 28 days, 26 (37%) patients had died. TPI values < 3.5 were correlated with more severe disease status (AUC 0.914; 95% CI: 0.847-0.981, P < 0.001), and TPI < 3.3 was associated with poor outcomes (AUC 0.937; 95% CI 0.880-0.994, P < 0.001). CONCLUSIONS: The tissue perfusion index (TPI), PtcCO2, and PtcO2/ FiO2 can predict the severity and outcome of severe and critical COVID-19.

A multimodal tissue perfusion measurement approach for the evaluation of the effect of pimobendan, an inodilator, in a porcine sepsis model.

Sepsis is associated with hypoperfusion and organ failure. The aims of the study were: 1) to assess the effect of pimobendan on macrocirculation and perfusion and 2) to describe a multimodal approach to the assessment of perfusion in sepsis and compare the evolution of the perfusion parameters. Eighteen anaesthetized female piglets were equipped for macrocirculation monitoring. Sepsis was induced by an infusion of Pseudomonas aeruginosa. After the occurrence of hypotension, animals were resuscitated. Nine pigs received pimobendan at the start of resuscitation maneuvers, the others received saline. Tissue perfusion was assessed using temperature gradients measured with infrared thermography (TG = core temperature - tarsus temperature), urethral perfusion index (uPI) derived from photoplethysmography and sublingual microcirculation (Sidestream dark field imaging device): De Backer score (DBs), proportion of perfused vessels (PPV), microvascular flow index (MFI) and heterogeneity index (HI). Arterial lactate and ScvO2 were also measured. Pimobendan did not improve tissue perfusion nor macrocirculation. It did not allow a reduction in the amount of noradrenaline and fluids administered. Sepsis was associated with tissue perfusion disorders: there were a significant decrease in uPI, PPV and ScvO2 and a significant rise in TG. TG could significantly predict an increase in lactate. Resuscitation was associated with a significant increase in uPI, DBs, MFI, lactate and ScvO2. There were fair correlations between the different perfusion parameters. In this model, pimobendan did not show any benefit. The multimodal approach allowed the detection of tissue perfusion alteration but only temperature gradients predicted the increase in lactatemia.

Tissue oxygen saturation is positively correlated with oxygen delivery and cardiac output in a canine hemorrhagic shock and resuscitation model.

OBJECTIVE: To determine if tissue oxygen saturation (StO2) correlates with oxygen delivery (DO2) and/or cardiac output (CO) in a canine hemorrhagic shock model. ANIMALS: 8 healthy purpose-bred dogs. METHODS: Dogs were anesthetized, and hemorrhagic shock was induced by withdrawing up to 60% of total blood volume, targeting a mean arterial pressure (MAP) of 40 mm Hg. The withdrawn blood was returned to the patient in 2 equal aliquots. Data was collected at 4 time points: 10 minutes after MAP was stabilized under anesthesia (time point [TP]-1), 10 minutes after up to 60% of blood volume was removed to target a MAP of 40 mm Hg (TP2), 10 minutes after the return of 50% of shed blood (TP3), and 10 minutes after the return of the remaining 50% of shed blood (TP4). Total blood volume withdrawn, StO2, CO, heart rate, and MAP were recorded, and DO2 was calculated at each TP. RESULTS: Mean StO2 significantly decreased between TP1 (77.8% [± 9.54]) and TP2 (44.8% [± 19.5]; P < .001 vs TP1). Mean StO2 increased to 63.1% (± 9.85) at TP3, but remained significantly lower compared to TP1 (P = .002). There was no difference between mean StO2 at TP4 (82.5% [± 12.6]) versus TP1 (P = .466). StO2 has a strong, positive correlation to both CO (r = 0.80; P < .001) and DO2 (r = 0.75; P < .001). CLINICAL RELEVANCE: A decrease in StO2 may be used in conjunction with physical examination findings and diagnostic parameters to support a diagnosis of shock. The return of shed blood was correlated with increases in StO2, DO2, and CO, suggesting that StO2 may be used as a marker of adequate resuscitation.

[Prospects of qualitative and quantitative assessment of bowel perfusion by fluorescent angiography with indocyanine green in colorectal surgery. First experience]. / Perspektivy kachestvennoi i kolichestvennoi otsenki perfuzii kishki metodom flyuorestsentnoi angiografii s indotsianinom zelenym v kolorektal'noi khirurgii. Pervyi opyt.

OBJECTIVE: To assess the possibilities of fluorescent detection system in qualitative and quantitative assessment of bowel perfusion in colorectal resections. MATERIAL AND METHODS: From May to August 2023, a single-center pilot cross-sectional unblinded study with inclusion of 18 patients with colon cancer (of left-sided - 12, of right-sided - 6, mean age - 72.9 years, m/w - 61/39%) was conducted. All patients underwent laparoscopic colorectal resections with extracorporeal stage of bowel transection. The evaluation of the bowel's ICG perfusion was conducted to assist in decision making about the level of its resection. Qualitative (visual) assessment was carried out in all 18 patients, in one patient twice, quantitative assessment of perfusion was conducted in 8 patients (left-sided resections - 6, right-sided hemicolectomy - 2). The qualitative evaluation was performed in real time on the analysis of the color gradient. The time parameters and fluorescence intensity at different level proximally and distally from the resection line were quantitatively estimated: Tstart - time of occurrence of minimal fluorescence in the areas of interest after the ICG injection (sec); Tmax - time to achieve maximum fluorescence intensity after the ICG injection (sec); Tmax-start - time interval between Tstart and Tmax, Imax - level of maximum fluorescence intensity (I). RESULTS: Visual qualitative analysis of fluorescence revealed unsatisfactory perfusion characteristics (black, dark-gray color) in the area planned by the surgeon to anastomose the bowel in 3 of 18 patients (16.6%). When analyzing the quantitative data of this group of patients, there was a 2-6-fold decrease in Imax level, and one patient had an increase in Tmax-start at the level of intended resection compared to the bowel's sections in the favorable zone. In all cases, the final bowel transection was conducted in the area of good perfusion. There was no clinical evidence of anastomotic dehiscence in the study group. CONCLUSION: Intraoperative evaluation of bowel perfusion is an important component of safe anastomosis formation in colorectal surgery. The use of ICG-FA allows to conduct qualitative and quantitative assessment of tissue perfusion of the bowel in order to assist in making intraoperative decisions. Quantitative evaluation of fluorescence provides more objective information about perfusion parameters. Imax and Tmax-start are the most promising quantitative indicators of local bowel's perfusion. Nevertheless, the precise interpretation of the quantitative indicators of ICG perfusion needs to be clarified.

Prognostic accuracy of mean arterial pressure and serum lactate level in patients with acute myocardial infarction.

BACKGROUND: Mean arterial pressure (MAP) can be used to evaluate macro-circulatory perfusion while serum lactate concentration is a marker of tissue perfusion. It is important to note that the primary objective of initial medical interventions is to restore microcirculatory perfusion rather than focusing solely on macro-hemodynamics. AIMS: We aimed to investigate the prognostic value of the combination of MAP and serum lactate levels measured on admission to the hospital in relation to patients' 30-day survival rate in patients with acute myocardial infarction (MI). METHODS: Data from 532 consecutive patients with acute MI treated with percutaneous coronary intervention were analyzed. The study endpoint was 30-day all-cause mortality. RESULTS: We found that both MAP and lactate levels were relevant predictors of the 30-day mortality in multivariable Cox regression analysis (HR, 0.83; 95% CI, 0.71-0.97; P = 0.02 and HR, 1.16; 95% CI, 1.06-1.16; P = 0.01, respectively). There was a significant increase in the prognostic performance in relation to 30-day mortality for the combination of both MAP and lactate levels in comparison to MAP alone (P = 0.03 for comparison between areas under the curve). Conversely, the combination of MAP and lactates did not add a significant prognostic value in comparison to lactates alone (P = 0.53 for comparison between areas under the curve). CONCLUSIONS: In patients with acute MI, serum lactate level seems to have a higher prognostic value in comparison to MAP. Our data suggest that on initial assessment of patients with acute myocardial infarction, we should move toward a tissue perfusion-based approach instead of focusing on a blood pressure-oriented strategy alone.

Incoherence between systemic and skin tissue response to transfusion in volume-resuscitated patients withoutacute bleeding.

Alterations in skin blood flow (SBF) may help to detect occult hypoperfusion in critically ill patients after fluid resuscitation. In this study, SBF is globally unaltered by red blood cell transfusion (RBCT) in non-bleeding critically ill patients after initial resuscitation; however, 37.5% of patients showed a significant increase in SBF. No correlation between relative changes in SBF and systemic variables after RBCT was observed.

Skin Mottling in Dark-skinned Indian Patients with Severe Septic Shock: A Window to the Circulation or a Closed Door?

Skin mottling has been found to be useful as a marker of peripheral hypoperfusion in shock in studies performed on fair-skinned patients. Whether skin mottling may be less apparent in dark-skinned patients, thus limiting its value in this patient population has not been studied. Jog et al. have performed an elegant study addressing this question, which is important and especially relevant to the Indian situation. They found that mottling is not easily visible in dark-skinned Indian patients, and when it becomes apparent, it is associated with a very high mortality. This study also throws up some areas for future research, including interobserver variability in the detection of mottling, and the hemodynamic and microcirculatory parameters associated with the appearance of mottling. Based on this study, the utility of skin mottling as a tool to guide hemodynamic management in severe septic shock in dark-skinned Indian patients is questionable. How to cite this article: Divatia JV. Skin Mottling in Dark-skinned Indian Patients with Severe Septic Shock: A Window to the Circulation or a Closed Door? Indian J Crit Care Med 2024;28(1):18-19.

Potential of acetaminophen on the sublingual microcirculation and peripheral tissue perfusion of febrile septic patients: prospective observational study.

BACKGROUND: Acetaminophen (ACT) has been studied in septic patients with detectable plasmatic levels of cell-free hemoglobin (Hb), where it demonstrated to inhibit the hemoprotein-mediated lipid peroxidation and oxidative injury, with a potential of beneficial effect on the endothelium. On the basis of this background, the aim of this study was to evaluate the sublingual microcirculation and the peripheral tissue perfusion before-and-after administration of ACT on clinical judgment in a cohort of febrile septic and septic shock patients. METHODS: Prospective observational study. 50 adult septic and septic shocks treated with ACT for pyrexia, where the sublingual microcirculation and the peripheral tissue perfusion with Near Infrared Spectroscopy (NIRS) and vascular occlusion test (VOT) were evaluated before ACT (t0), after 30 min (t1) and after 2 h (t2). Cell-free Hb and the markers of oxidative stress and endothelial damage were measured at t0 and t2. RESULTS: The study showed a significant increase of the density of the perfused small and total vessels of the sublingual microcirculation 30 min after the infusion of ACT; it also showed an increase of the Microvascular Flow Index (MFI) and a decrease in the heterogeneity of the flow. At a peripheral muscular level, we found an acceleration in the reperfusion curve after VOT at t1, expression of a higher reactivity of the microvasculature. CONCLUSIONS: ACT infusion did not show a clear correlation with cell-free Hb; however, it exhibited protective effect toward the microcirculation that was evident in particular in septic patients. This correlation merits further exploration.

Albumin versus saline infusion for sepsis-related peripheral tissue hypoperfusion: a proof-of-concept prospective study.

BACKGROUND: Albumin has potential endothelial protective effects through antioxidant and anti-inflammatory properties. However, the effect of albumin on peripheral tissue perfusion in human sepsis remains poorly known. METHODS: Bi-centric prospective study included patients with sepsis with or without shock and prolonged CRT > 3 s despite initial resuscitation. Clinicians in charge of the patients were free to infuse either saline 500 mL or human serum albumin 20% 100 mL over 15 min. Global hemodynamic parameters as well as peripheral tissue perfusion were analyzed after 1 (H1) and 4 h (H4). The primary endpoint was CRT normalization (< 3 s) at H1. RESULTS: 62 patients were screened, and 50 patients (13 sepsis and 37 septic shock) were included, 21 in the saline group and 29 in the albumin group. SOFA score was 8 [5-11], and SAPS II was 53 [45-70]. Median age was 68 [60-76] years with a higher proportion of men (74%). The primary sources of infection were respiratory (54%) and abdominal (24%). At baseline, comorbidities, clinical and biological characteristics were similar between groups. At H1, CRT normalization (< 3 s) was more frequent in patients receiving albumin as compared to patients treated by saline (63 vs 29%, P = 0.02). The decrease in fingertip CRT was more important in the albumin group when compared to saline group (- 1.0 [- 0.3; - 1.5] vs - 0.2 [- 0.1; - 1.1] seconds, P = 0.04) as well as decrease in mottling score. At H4, beneficial effects of albumin on peripheral tissue perfusion were maintained and urinary output trended to be higher in the albumin group (1.1 [0.5-1.8] vs 0.7 [0.5-0.9] ml/kg/h, P = 0.08). Finally, arterial lactate level did not significantly change between H0 and H4 in the saline group but significantly decreased in the albumin group (P = 0.03). CONCLUSION: In patients with resuscitated sepsis, albumin infusion might lead to greater improvement of tissue hypoperfusion compared to saline. CLINICALTRIALS: gov Identifier: NCT05094856.

Non-invasive evaluation of vascular permeability in formalin-induced orofacial pain model using infrared thermography.

Enhanced vascular permeability at the site of injury is a prominent feature in acute inflammatory pain models, commonly assessed through the Evans Blue test. However, this invasive test requires euthanasia, thereby precluding further investigations on the same animal. Due to these limitations, the integration of non-invasive tools such as IRT has been sought. Here, we aimed to evaluate the use of thermography in a common orofacial pain model that employs formalin as a chemical irritant to induce local orofacial inflammation. Male Hannover rats (290-300 g, N = 43) were used. In the first approach, radiometric images were taken before and after formalin administration, assessing temperature changes and extravasated Evans Blue. The second approach included capturing pre- and post-formalin test radiometric images, followed by cytokine measurements in excised vibrissae tissue. Rats were anesthetized for vibrissae tissue collection, allowing correlations between thermographic patterns, nocifensive behavior duration, and cytokine levels in this area. Our findings revealed a positive correlation between local temperature, measured via thermography, and vascular permeability in the contralateral (r2 = 0.3483) and ipsilateral (r2 = 0.4502) side, measured using spectrophotometry. The obtained data supports the notion that thermography-based temperature assessment can effectively evaluate vascular permeability in the orofacial region.

Comparing the effectiveness of novel high-end compression garment with common compression garment and kinesio tape in preventing edema and improving tissue perfusion in lower extremities.

CONTEXT: Global sales of compression garments have risen sharply in recent years. Due to the availability of a wide range of compression garments, this study aims to evaluate the effect of two types of compression garments and kinesio tape on edema formation and tissue perfusion in the lower extremities. Over-the-counter compression knee stockings and kinesio tape were compared with a prototype of high-end compression stockings that combine kinesio tape and a common knee bandage. The high-end compression stockings were designed by Cube with the aim of combining the positive effects of kinesio tape and compression garments on edema formation and tissue perfusion. DESIGN: Clinical cross-over study. METHODS: Before and after a 6-hour compression period, the knee regions on both, the treated and non-treated leg, of participants were examined using a 3-D scan to detect changes in volume. Also measured were local temperature (°C), oxygen saturation (SpO2), perfusion index (Pi), blood pressure (mmHg), compression pressure (mmHg), range of motion, body-mass-index (BMI) and limb-circumference (cm). Two different types of compression garments were examined: a novel high-end compression stocking (A) and a common compression stocking (B). In addition, kinesio tape was compared to compression garments (C). After each experimental day, a one-day break was taken to prevent an unwanted overlay effect. Male and female participants between the ages of 18 and 60 were randomly selected. RESULTS: The high-end compression garment (A) showed a statistically significant (P = 0.009) reduction of edema intraindividually. Comparing the three treatment groups, compression (A) lead to a reduction of edema. However, the reduction was not statistically significant (P = 0.585). The compression garment B and kinesio tape showed an increase in edema in the lower limb. There was a positive correlation between the highest compression pressure (A: 9.8 mmHg) and volume decrease over the period of 6 hours. Lighter compression (B: 8.2 mmHg) led to an increase in leg volume after compression application over 6 hours. There was no significant difference in tissue oxygen saturation with the two types of compression and kinesio tape. The tissue temperature below the compression garment was highest in the compression group A. Nevertheless, we could not demonstrate a statistically significant correlation between tissue temperature and volume difference.The range in motion of the lower limb decreased after 6 hours with both compression A and B and with kinesio tape. CONCLUSION: The novel bandage showed a statistically significant reduction in edema when compared intraindividually, but no statistically significant advantage was found when compared with the other compression garment B and kinesio tape.Despite the widespread use of kinesio tape, we did not find any improvement in the range of motion, edema prevention and circulation in the lower limb after application of kinesio tape.

A review of using CO2-derived variables to detect tissue hypoperfusion during cardiopulmonary bypass.

Complications after cardiac surgery with cardiopulmonary bypass (CPB) are associated with increased morbidity and mortality. Early detection and prompt reversion of tissue hypoperfusion during CPB are key factors to reduce organ dysfunction after cardiac surgery. CO2 (carbon dioxide)-derived variables which are easy to assess and routinely available to evaluate the adequacy of macro- and microcirculation may offer important information on the adequacy of the perfusion during CPB. However, since some practical issues remain unsolved in providing a reliable measurement of CO2 removal from the patient, CO2-derived variables are not widely monitoring during CPB. This review aims to demonstrate the basic principles of CO2-derived variables during CPB, the available techniques to assess CO2-derived variables on CPB and the clinically relevant applications.

The microcirculation in perioperative medicine: a narrative review.

The microcirculation describes the network of the smallest vessels in our cardiovascular system. On a microcirculatory level, oxygen delivery is determined by the flow of oxygen-carrying red blood cells in a given single capillary (capillary red blood cell flow) and the density of the capillary network in a given tissue volume (capillary vessel density). Handheld vital videomicroscopy enables visualisation of the capillary bed on the surface of organs and tissues but currently is only used for research. Measurements are generally possible on all organ surfaces but are most often performed in the sublingual area. In patients presenting for elective surgery, the sublingual microcirculation is usually intact and functional. Induction of general anaesthesia slightly decreases capillary red blood cell flow and increases capillary vessel density. During elective, even major, noncardiac surgery, the sublingual microcirculation is preserved and remains functional, presumably because elective noncardiac surgery is scheduled trauma and haemodynamic alterations are immediately treated by anaesthesiologists, usually restoring the macrocirculation before the microcirculation is substantially impaired. Additionally, surgery is regional trauma and thus likely causes regional, rather than systemic, impairment of the microcirculation. Whether or not the sublingual microcirculation is impaired after noncardiac surgery remains a subject of ongoing research. Similarly, it remains unclear if cardiac surgery, especially with cardiopulmonary bypass, impairs the sublingual microcirculation. The effects of therapeutic interventions specifically targeting the microcirculation remain to be elucidated and tested. Future research should focus on further improving microcirculation monitoring methods and investigating how regional microcirculation monitoring can inform clinical decision-making and treatment.

Contrast-enhanced ultrasonography of the thyroid gland in healthy dogs, hypothyroid dogs and dogs with non-thyroidal illness.

Diagnosis of canine hypothyroidism remains challenging, as non-thyroidal illness (NTI)-syndrome and medical treatment can influence thyroid hormone concentrations. Conventional ultrasound may give additional hints, however high interobserver variability has been described. Contrast-enhanced ultrasound (CEUS) allows detection of changes in tissue perfusion. The purpose of the present study was to assess the possible diagnostic value of CEUS regarding diagnosis of hypothyroidism. CEUS of the thyroid gland was performed in 52 healthy dogs, 16 hypothyroid dogs, and 20 NTI patients. The following perfusion parameters were calculated: Thyroid/carotid artery (TG/CA) ratios for peak enhancement (PE) and area under the curve (AUC), time to peak (TTP) and wash-in and wash-out rates (WiR, WoR) of the thyroid gland. Impact of sedation on perfusion parameters was investigated in 8 calm healthy dogs which were examined before and after sedation using midazolam and butorphanol. Significantly higher median TG/CA ratios for PE were detected for the left and right thyroid lobe in dogs with hypothyroidism (0.97/0.96) compared to healthy dogs (0.85/0.85) and dogs with NTI (0.84/0.84). AUCs were also significantly increased in hypothyroid dogs when compared to other groups. Dogs with NTI showed significantly lower WiR and WoR compared to other groups. Values for TTP were not significantly different between groups. Sedation had only impact on results of TTP which was significantly prolonged in sedated dogs. In conclusion, CEUS of the thyroid gland can provide an additional tool for diagnosis of hypothyroidism in dogs and support its differentiation from NTI. Sedation has limited impact on CEUS results.

The Urethral Perfusion Index During Off-Pump Coronary Artery Bypass Surgery: An Observational Study.

OBJECTIVES: The IKORUS system (Vygon, Écouen, France) allows continuous monitoring of the urethral perfusion index (uPI) using a photoplethysmographic sensor mounted near the base of the balloon of a dedicated urinary catheter. We aimed to test the hypothesis that the uPI decreases during off-pump coronary artery bypass (OPCAB) surgery and to investigate the relationship between the uPI and macrocirculatory variables. DESIGN: Prospective observational study. SETTING: University Medical Center Hamburg-Eppendorf, Hamburg, Germany. PARTICIPANTS: Twenty patients having OPCAB surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was changes in the uPI during OPCAB surgery. We additionally investigated associations between the uPI and cardiac output, mean arterial pressure, heart rate, and point-of-care variables. Twenty patients with 24,137 uPI measurements were included. Overall, there was a high interindividual variability in the uPI. Compared with the preparation phase (during which the median [interquartile range] uPI was 7.7 [5.6-12.0]), the uPI decreased by 14% (95% CI 13%-15%) during the bypass grafting phase, by 35% (95% CI 34%-36%) during the cardiac positioning phase, and by 7% (95% CI 6%-9%) during hemostasis. There was no clinically important association between uPI and either cardiac output, mean arterial pressure, or heart rate. CONCLUSIONS: The uPI decreases during OPCAB surgery, specifically during the cardiac positioning phase. There was no clinically important association between uPI and either cardiac output, mean arterial pressure, or heart rate. It, therefore, remains to be determined whether intraoperative uPI decreases are clinically important, reflect alterations in intra-abdominal tissue perfusion that are not reflected by systemic macrohemodynamics, and can help clinicians guide therapeutic interventions.