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Mota-Silva I, Castanho MARB, Silva-Herdade AS. Towards Non-Invasive Intravital Microscopy: Advantages of Using the Ear Lobe Instead of the Cremaster Muscle. Life (Basel) 2023; 13:life13040887. [PMID: 37109417 PMCID: PMC10145854 DOI: 10.3390/life13040887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/10/2023] [Accepted: 03/20/2023] [Indexed: 03/29/2023] Open
Abstract
Inflammation is essential in the protection of the organism and wound repair, but in cases of chronic inflammation can also cause microvasculature deterioration. Thus, inflammation monitorization studies are important to test potential therapeutics. The intravital microscopy (IVM) technique monitors leukocyte trafficking in vivo, being a commonly used procedure to report systemic conditions. Although the cremaster muscle, an established protocol for IVM, may affect the hemodynamics because of its surgical preparation, only male animals are used, and longitudinal studies over time are not feasible. Thinking how this impacts future studies, our aim is to understand if the IVM technique can be successfully performed using the ear lobe instead of the cremaster muscle. Elevated IL-1β plasmatic concentrations confirmed the systemic inflammation developed in a diabetic animal model, while the elevated number of adherent and rolling leukocytes in the ear lobe allowed for the same conclusion. Thus, this study demonstrates that albeit its thickness, the ear lobe protocol for IVM is efficient, non-invasive, more reliable, cost-effective and timesaving.
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Roy TK, Secomb TW. Effects of impaired microvascular flow regulation on metabolism-perfusion matching and organ function. Microcirculation 2020; 28:e12673. [PMID: 33236393 DOI: 10.1111/micc.12673] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 11/17/2020] [Indexed: 12/14/2022]
Abstract
Impaired tissue oxygen delivery is a major cause of organ damage and failure in critically ill patients, which can occur even when systemic parameters, including cardiac output and arterial hemoglobin saturation, are close to normal. This review addresses oxygen transport mechanisms at the microcirculatory scale, and how hypoxia may occur in spite of adequate convective oxygen supply. The structure of the microcirculation is intrinsically heterogeneous, with wide variations in vessel diameters and flow pathway lengths, and consequently also in blood flow rates and oxygen levels. The dynamic processes of structural adaptation and flow regulation continually adjust microvessel diameters to compensate for heterogeneity, redistributing flow according to metabolic needs to ensure adequate tissue oxygenation. A key role in flow regulation is played by conducted responses, which are generated and propagated by endothelial cells and signal upstream arterioles to dilate in response to local hypoxia. Several pathophysiological conditions can impair local flow regulation, causing hypoxia and tissue damage leading to organ failure. Therapeutic measures targeted to systemic parameters may not address or may even worsen tissue oxygenation at the microvascular level. Restoration of tissue oxygenation in critically ill patients may depend on restoration of endothelial cell function, including conducted responses.
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Affiliation(s)
- Tuhin K Roy
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, 85724, USA
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Effects of Diabetes on Microcirculation and Leukostasis in Retinal and Non-Ocular Tissues: Implications for Diabetic Retinopathy. Biomolecules 2020; 10:biom10111583. [PMID: 33233433 PMCID: PMC7700516 DOI: 10.3390/biom10111583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/07/2020] [Accepted: 11/18/2020] [Indexed: 11/16/2022] Open
Abstract
Changes in retinal microcirculation are associated with the development of diabetic retinopathy (DR). However, it is unclear whether such changes also develop in capillary beds of other non-retinal tissues. Here, we investigated microcirculatory changes involving velocity of rolling neutrophils, adherence of neutrophils, and leukostasis during development of retinal vascular lesions in diabetes in other non-retinal tissues. Intravital microscopy was performed on post-capillary venules of cremaster muscle and ear lobe of mice with severe or moderate diabetes and compared to those of non-diabetic mice. Additionally, number and velocity of rolling leukocytes, number of adherent leukocytes, and areas of leukostasis were quantified, and retinal capillary networks were examined for acellular capillaries (AC) and pericyte loss (PL), two prominent vascular lesions characteristic of DR. The number of adherent neutrophils and areas of leukostasis in the cremaster and ear lobe post-capillary venules of diabetic mice was increased compared to those of non-diabetic mice. Similarly, a significant increase in the number of rolling neutrophils and decrease in their rolling velocities compared to those of non-diabetic control mice were observed and severity of diabetes exacerbated these changes. Understanding diabetes-induced microcirculatory changes in cremaster and ear lobe may provide insight into retinal vascular lesion development in DR.
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Puchwein-Schwepcke AF, Schottmayer K, Mormanová Z, Dreyhaupt J, Genzel-Boroviczeny O, Thome UH. Permissive Hypercapnia Results in Decreased Functional Vessel Density in the Skin of Extremely Low Birth Weight Infants. Front Pediatr 2018; 6:52. [PMID: 29662873 PMCID: PMC5890181 DOI: 10.3389/fped.2018.00052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 02/23/2018] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Ventilator-induced lung injury with subsequent bronchopulmonary dysplasia remains an important issue in the care of extremely low-birth-weight infants. Permissive hypercapnia has been proposed to reduce lung injury. Hypercapnia changes cerebral perfusion, but its influence on the peripheral microcirculation is unknown. METHODS Data were collected from 12 infants, who were randomized to a permissive high PCO2 target group (HTG) or a control group (CG). Inclusion criteria were birth weight between 400 and 1,000 g, gestational age from 23 to 28 6/7 weeks, intubation during the first 24 h of life, and no malformations. The PCO2 target range was increased stepwise in both groups for weaning and was always 15 mmHg higher in the HTG than in the CG. Skin microvascular parameters were assessed non-invasively with sidestream dark field imaging on the inner side of the right arm every 24 h during the first week of life and on the 14th day of life. RESULTS Infants in the HTG had significantly higher max. PCO2 exposure, which was associated with a significantly and progressively reduced functional vessel density (FVD, p < 0.01). Moreover, there were significant differences in the diameter distribution over time, with HTG subjects having fewer small vessels but more large vessels. CONCLUSION High PCO2 levels significantly impaired peripheral microcirculation in preterm infants, as shown by a decreased FVD, presumably secondary to peripheral vasoconstriction. ISRCTN 56143743.
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Affiliation(s)
| | - Kristina Schottmayer
- Divsion of Neonatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Zuzana Mormanová
- Divsion of Neonatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Jens Dreyhaupt
- Institute for Epidemiology and Medical Biometry, University of Ulm, Ulm, Germany
| | - Orsolya Genzel-Boroviczeny
- Divsion of Neonatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Ulrich H Thome
- Divsion of Neonatology, University Hospital of Leipzig, Leipzig, Germany
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DeBarros M, Causey MW, Chesley P, Martin M. Reliability of Continuous Non-Invasive Assessment of Hemoglobin and Fluid Responsiveness: Impact of Obesity and Abdominal Insufflation Pressures. Obes Surg 2016; 25:1142-8. [PMID: 25399349 DOI: 10.1007/s11695-014-1505-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND During surgery, proper fluid resuscitation and hemostatic control is critical. Pleth variability index (PVI) is advocated as a reliable way of optimizing intraoperative fluid resuscitation. PVI is a measure of dynamic change in perfusion index during a complete respiratory cycle. Non-invasive monitoring of total hemoglobin could provide a reliable means to determine need for transfusion. We analyzed the impact of insufflation and obesity on non-invasive measurements of hemoglobin and PVI in laparoscopic procedures to validate reliability of fluid responsiveness and hemoglobin levels. METHODS A non-invasive hemoglobin and PVI monitoring device was prospectively analyzed in patients undergoing abdominal operations. Patients were stratified by open and laparoscopic approach and obesity (body mass index (BMI) ≥35). PVI and hemoglobin values were assessed before, during, and after insufflation and compared to control patients undergoing open surgery. RESULTS Sixty-three patients were enrolled (mean age 42 years; 71 % male; mean BMI 36) with 24 patients laparoscopic non-obese (LNO), 20 laparoscopic obese (LO), and 19 undergoing open operations. There was no significant blood loss. Hemoglobin did not change significantly before or after insufflation. There was false elevation of PVI with insufflation and more pronounced in obese patients. CONCLUSIONS Insufflation or obesity was not associated with significant variations in hemoglobin. Non-invasive monitoring of hemoglobin is useful in laparoscopic procedures in obese and non-obese patients. PVI values should be used cautiously during laparoscopic procedures, particularly in obese patients.
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Affiliation(s)
- Mia DeBarros
- Department of Surgery, Madigan Army Medical Center, 9040a Fitzsimmons Drive, Tacoma, WA, 98431, USA,
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Cornette J, Buijs EAB, Duvekot JJ, Herzog E, Roos-Hesselink JW, Rizopoulos D, Meima M, Steegers EAP. Hemodynamic effects of intravenous nicardipine in severely pre-eclamptic women with a hypertensive crisis. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2016; 47:89-95. [PMID: 25721057 DOI: 10.1002/uog.14836] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/18/2015] [Accepted: 02/22/2015] [Indexed: 06/04/2023]
Abstract
OBJECTIVE Nicardipine permits rapid control of blood pressure in women with severe pre-eclampsia (PE) and hypertensive crisis. Our objective was to investigate its maternal and fetal hemodynamic effects. METHODS Ten severely pre-eclamptic pregnant women who required intravenous nicardipine for severe hypertension were included in this prospective observational trial. Maternal macrocirculation was assessed by transthoracic echocardiography. Maternal microcirculatory perfusion was examined sublingually with the sidestream dark field imaging technique. Fetal hemodynamics were assessed by Doppler examinations of the uteroplacental and fetal circulations. Maternal cardiac output, total vascular resistance, mitral E/A ratio and capillary heterogeneity index, uterine artery pulsatility index and fetal cerebroplacental ratio were considered primary outcomes. Paired measurements, obtained before administration of nicardipine infusion and after stabilization of blood pressure, were compared. RESULTS Administration of nicardipine significantly reduced the mean arterial blood pressure (median difference, 26 mmHg; P = 0.002) and total vascular resistance (median difference, 791 dynes × s/cm(5) ; P = 0.002) in all included women. This induced a reflex tachycardia with consequent increase in cardiac output of 1.55 L/min (P = 0.004). There were no significant changes in the other determinants of maternal or fetal hemodynamic parameters. CONCLUSIONS Nicardipine effectively reduces blood pressure through selective afterload reduction that triggers an increase in cardiac output, without affecting maternal diastolic function, or microcirculatory, uteroplacental or fetal perfusion. This hemodynamic response is uniform and predictable. Fetomaternal cardiovascular profiling can be achieved by combining transthoracic echocardiography with obstetric Doppler.
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Affiliation(s)
- J Cornette
- Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - E A B Buijs
- Department of Paediatric Surgery, Sophia Children's Hospital, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - J J Duvekot
- Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - E Herzog
- Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - J W Roos-Hesselink
- Department of Cardiology, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - D Rizopoulos
- Department of Biostatistics, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - M Meima
- Department of Internal Medicine, Division of Pharmacology, Vascular and Metabolic Diseases, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - E A P Steegers
- Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
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In Vivo Microdialysis To Determine Subcutaneous Interstitial Fluid Penetration and Pharmacokinetics of Fluconazole in Intensive Care Unit Patients with Sepsis. Antimicrob Agents Chemother 2015; 60:827-32. [PMID: 26596947 DOI: 10.1128/aac.02461-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 11/14/2015] [Indexed: 12/22/2022] Open
Abstract
The objective of the study was to describe the subcutaneous interstitial fluid (ISF) pharmacokinetics of fluconazole in critically ill patients with sepsis. This prospective observational study was conducted at two tertiary intensive care units in Australia. Serial fluconazole concentrations were measured over 24 h in plasma and subcutaneous ISF using microdialysis. The concentrations in plasma and microdialysate were measured using a validated high-performance liquid chromatography system with electrospray mass spectrometer detector method. Noncompartmental pharmacokinetic analysis was performed. Twelve critically ill patients with sepsis were enrolled. The mean in vivo fluconazole recovery rates ± standard deviation (SD) for microdialysis were 51.4% ± 16.1% with a mean (±SD) fluconazole ISF penetration ratio of 0.52 ± 0.30 (coefficient of variation, 58%). The median free plasma area under the concentration-time curve from 0 to 24 h (AUC0-24) was significantly higher than the median ISF AUC0-24 (340.4 versus 141.1 mg · h/liter; P = 0.004). There was no statistical difference in median fluconazole ISF penetration between patients receiving and not receiving vasopressors (median, 0.28 versus 0.78; P = 0.106). Both minimum and the maximum concentrations of drug in serum (Cmax and Cmin) showed a significant correlation with the fluconazole plasma exposure (Cmax, R(2) = 0.86, P < 0.0001; Cmin, R(2) = 0.75, P < 0.001). Our data suggest that fluconazole was distributed variably, but incompletely, from plasma into subcutaneous interstitial fluid in this cohort of critically ill patients with sepsis. Given the variability of fluconazole interstitial fluid exposures and lack of clinically identifiable factors by which to recognize patients with reduced distribution/exposure, we suggest higher than standard doses to ensure that drug exposure is adequate at the site of infection.
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Hanson J, Lee SJ, Hossain MA, Anstey NM, Charunwatthana P, Maude RJ, Kingston HWF, Mishra SK, Mohanty S, Plewes K, Piera K, Hassan MU, Ghose A, Faiz MA, White NJ, Day NPJ, Dondorp AM. Microvascular obstruction and endothelial activation are independently associated with the clinical manifestations of severe falciparum malaria in adults: an observational study. BMC Med 2015; 13:122. [PMID: 26018532 PMCID: PMC4453275 DOI: 10.1186/s12916-015-0365-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/12/2015] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Microvascular obstruction and endothelial dysfunction have both been linked to tissue hypoperfusion in falciparum malaria, but their relative contributions to the disease's pathogenesis and outcome are unknown. METHODS Microvascular blood flow was quantified in adults with severe falciparum malaria on their admission to hospital; plasma biomarkers of endothelial function were measured simultaneously. The relationship between these indices and the patients' clinical findings and in-hospital course was examined. RESULTS Microvascular obstruction was observed in 119/142 (84 %) patients; a median (interquartile range (IQR)) of 14.9 % (6.6-34.9 %) of capillaries were obstructed in patients that died versus 8.3 % (1.7-26.6 %) in survivors (P = 0.039). The proportion of obstructed capillaries correlated with the estimated parasite biomass (rs = 0.25, P = 0.004) and with plasma lactate (rs = 0.38, P <0.0001), the strongest predictor of death in the series. Plasma angiopoietin-2 (Ang-2) concentrations were markedly elevated suggesting widespread endothelial activation; the median (IQR) Ang-2 concentration was 21.9 ng/mL (13.4-29.4 ng/mL) in patients that died versus 14.9 ng/mL (9.8-29.3 ng/mL) in survivors (P = 0.035). Ang-2 concentrations correlated with estimated parasite biomass (rs = 0.35, P <0.001) and plasma lactate (rs = 0.37, P <0.0001). Microvascular obstruction and Ang-2 concentrations were not significantly correlated with each other (rs = 0.17, P = 0.06), but were independently associated with plasma lactate (P <0.001 and P = 0.002, respectively). CONCLUSIONS Microvascular obstruction and systemic endothelial activation are independently associated with plasma lactate, the strongest predictor of death in adults with falciparum malaria. This supports the hypothesis that the two processes make an independent contribution to the pathogenesis and clinical manifestations of the disease.
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Affiliation(s)
- Josh Hanson
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Global Health Division, Menzies School of Health Research, Darwin, Australia.
| | - Sue J Lee
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| | - Md Amir Hossain
- Department of Medicine, Chittagong Medical College Hospital, Chittagong, Bangladesh.
| | - Nicholas M Anstey
- Global Health Division, Menzies School of Health Research, Darwin, Australia.
| | - Prakaykaew Charunwatthana
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Richard J Maude
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| | - Hugh W F Kingston
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Global Health Division, Menzies School of Health Research, Darwin, Australia.
| | - Saroj K Mishra
- Department of Medicine, Ispat Hospital, Rourkela, Orissa, India.
| | - Sanjib Mohanty
- Department of Medicine, Ispat Hospital, Rourkela, Orissa, India.
| | - Katherine Plewes
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Kim Piera
- Global Health Division, Menzies School of Health Research, Darwin, Australia.
| | - Mahtab U Hassan
- Department of Medicine, Chittagong Medical College Hospital, Chittagong, Bangladesh.
| | - Aniruddha Ghose
- Department of Medicine, Chittagong Medical College Hospital, Chittagong, Bangladesh.
| | - M Abul Faiz
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Specialized Care and Research, Chittagong, Bangladesh. .,Dev Care Foundation, Dhaka, Bangladesh.
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
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Silva H, Ferreira H, Bujan MJ, Rodrigues LM. Regarding the quantification of peripheral microcirculation--Comparing responses evoked in the in vivo human lower limb by postural changes, suprasystolic occlusion and oxygen breathing. Microvasc Res 2015; 99:110-7. [PMID: 25872021 DOI: 10.1016/j.mvr.2015.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 04/05/2015] [Accepted: 04/06/2015] [Indexed: 11/25/2022]
Abstract
The human skin is an interesting model to explore microcirculation, particularly if using noninvasive technologies such as LDF (Laser Doppler Flowmetry) and tc (transcutaneous) gasimetry and methods as near as possible from the normal physiological state. In this study, we combined those technologies with three classical approaches--leg raising from supine, suprasystolic occlusion (in the ankle), and normobaric oxygen breathing to explore distal peripheral circulation in the foot. These methods are often cited, but a comparative assessment has not been done. The goal of this study was to identify relevant flow related descriptors, method-related advantages and pitfalls, and eventually, to find the best experimental approach. Volunteers (both genders, 22.1 ± 3.7 years old) were subjected to these methods and variables registered during basal, challenge and stabilization phases. Descriptive and comparative statistics were obtained, adopting a 95% confidence level. All flow-related quantitative descriptors potentially useful for the analysis were identified and compared. As expected, male patients consistently showed higher LDF levels and transepidermal water loss (TEWL) and lower tcpO2 values. However, lower results were recorded in the supine position, suggesting a postural dependence. Both leg raising and suprasystolic occlusion produced a hyperemic response after provocation, although different in magnitude, significantly reducing LDF and tcpO2 during provocation. The oxygen breathing method provided the most patient-friendly protocol, consistently reducing LDF (potentially by the inhibition of production of local vasodilators). TEWL increased during the provocation phase in all protocols, although not significantly. Baseline tcpO2 was found to correlate positively with the peak tcpO2 during oxygen breathing and basal LDF with peak flow during leg raising and suprasystolic occlusion. No statistical correlation between TEWL and LDF could be demonstrated under the current experimental conditions. We conclude that although equally useful considering the purpose, these methods involve very different practicalities and do not provide the same information. Also noteworthy, LDF is a highly sensitive indicator that could be further explored to look deeper into blood flow regulating mechanisms.
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Affiliation(s)
- Henrique Silva
- CBIOS - Universidade Lusófona's Research Center for Biosciences and Health Technologies, Lisboa, Portugal; Pharmacol. Sc Depart - Universidade de Lisboa, Faculty of Pharmacy, Lisboa, Portugal
| | - Hugo Ferreira
- IBEB - Biophysics and Biomedical Engineering Institute, Universidade de Lisboa Faculty of Sciences, Lisboa, Portugal
| | - Ma Julia Bujan
- Dept Medicine and Medical Specialities, CIBER-BBN Alcalá de Henares, Madrid, Spain
| | - Luis Monteiro Rodrigues
- CBIOS - Universidade Lusófona's Research Center for Biosciences and Health Technologies, Lisboa, Portugal; Pharmacol. Sc Depart - Universidade de Lisboa, Faculty of Pharmacy, Lisboa, Portugal.
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Donndorf P, Park H, Vollmar B, Alms A, Gierer P, Steinhoff G, Kaminski A. Impact of closed minimal extracorporeal circulation on microvascular tissue perfusion during surgical aortic valve replacement: intravital imaging in a prospective randomized study. Interact Cardiovasc Thorac Surg 2014; 19:211-7. [PMID: 24796334 DOI: 10.1093/icvts/ivu131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES Closed minimal extracorporeal circulation (MECC) systems currently do not represent the standard of surgical care for open-heart surgery. Yet, considering the beneficial results reported for coronary artery bypass graft (CABG) surgery, we used an MECC system in aortic valve replacement (AVR) and analysed the effects on intraoperative microvascular perfusion in comparison with conventional open extracorporeal circulation (CECC). METHODS In the current study, we analysed alterations in microvascular perfusion at 4 predefined time points (T1-T4) during surgical AVR utilizing orthogonal polarization spectral (OPS) imaging. Twenty patients were randomized for being operated on utilizing either MECC or CECC. Changes in functional capillary density (FCD, cm/cm(2)), mircovascular blood flow velocity (mm/s) and vessel diameter (μm) were analysed by a blinded investigator. RESULTS After the start of extracorporeal circulation and aortic cross-clamping (T2), both groups showed a significant drop in FCD, but with a significantly higher FCD in the MECC group (153.1 ± 15.0 cm/cm² in the CECC group vs 160.8 ± 12.2 cm/cm² in the MECC group, P = 0.034). During the late phase of the cardiopulmonary bypass (CPB) (T3), the FCD was still significantly depressed in both treatment groups (153.5 ± 14.6 cm/cm² in the CECC group, P <0.05 vs 'T1'; 159.5 ± 12.4 cm/cm² in the MECC group, P <0.05 versus 'T1'). After termination of CPB (T4), the FCD recovered in both groups to baseline values. Microvascular blood flow velocity tended to remain at a higher level in the MECC group, whereas haemodilution during CPB was significantly reduced in the MECC group. CONCLUSIONS The use of MECC in AVR did not affect procedural safety and, resulted in beneficial preservation of microvascular blood flow velocity and significantly reduced haemodilution during CPB. In contrast to CABG surgery, the use of MECC did not improve FCD during surgical AVR. Clinical advantages possibly resulting from attenuated haemodilution and preservation of microvascular blood flow velocity require further validation in larger patient cohorts.
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Affiliation(s)
- Peter Donndorf
- Department of Cardiac Surgery, University of Rostock, Rostock, Germany
| | - Hannah Park
- Department of Cardiac Surgery, University of Rostock, Rostock, Germany
| | - Brigitte Vollmar
- Institute of Experimental Surgery, University of Rostock, Rostock, Germany
| | - Angela Alms
- Department of Anesthesiology and Intensive Care Medicine, University of Rostock, Rostock, Germany
| | - Philipp Gierer
- Department of Trauma and Reconstructive Surgery, University of Rostock, Rostock, Germany
| | - Gustav Steinhoff
- Department of Cardiac Surgery, University of Rostock, Rostock, Germany
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Hong DM, Lee JM, Seo JH, Min JJ, Jeon Y, Bahk JH. Pulse pressure variation to predict fluid responsiveness in spontaneously breathing patients: tidal vs. forced inspiratory breathing. Anaesthesia 2014; 69:717-22. [PMID: 24773446 DOI: 10.1111/anae.12678] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2014] [Indexed: 02/06/2023]
Abstract
We evaluated whether pulse pressure variation can predict fluid responsiveness in spontaneously breathing patients. Fifty-nine elective thoracic surgical patients were studied before induction of general anaesthesia. After volume expansion with hydroxyethyl starch 6 ml.kg(-1) , patients were defined as responders by a ≥ 15% increase in the cardiac index. Haemodynamic variables were measured before and after volume expansion and pulse pressure variations were calculated during tidal breathing and during forced inspiratory breathing. Median (IQR [range]) pulse pressure variation during forced inspiratory breathing was significantly higher in responders (n = 29) than in non-responders (n = 30) before volume expansion (18.2 (IQR 14.7-18.2 [9.3-31.3])% vs. 10.1 (IQR 8.3-12.6 [4.8-21.1])%, respectively, p < 0.001). The receiver-operating characteristic curve revealed that pulse pressure variation during forced inspiratory breathing could predict fluid responsiveness (area under the curve 0.910, p < 0.0001). Pulse pressure variation measured during forced inspiratory breathing can be used to guide fluid management in spontaneously breathing patients.
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Affiliation(s)
- D M Hong
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Korea
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12
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Karaca Ü, Schram MT, Houben AJHM, Muris DMJ, Stehouwer CDA. Microvascular dysfunction as a link between obesity, insulin resistance and hypertension. Diabetes Res Clin Pract 2014; 103:382-7. [PMID: 24438874 DOI: 10.1016/j.diabres.2013.12.012] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 12/18/2013] [Accepted: 12/18/2013] [Indexed: 01/07/2023]
Abstract
Impaired microvascular dilatation from any cause and impaired insulin-mediated capillary recruitment in particular result in suboptimal delivery of glucose and insulin to skeletal muscle, and subsequently impairment of glucose disposal (insulin resistance). In addition, microvascular dysfunction, through functional and/or structural arteriolar and capillary drop-out, and arteriolar constriction, increases peripheral resistance and thus blood pressure. Microvascular dysfunction may thus constitute a pathway that links insulin resistance and hypertension. Overweight and obesity may be an important cause of microvascular dysfunction. Mechanisms linking overweight and obesity to microvascular dysfunction include changes in the secretion of adipokines leading to increased levels of free fatty acids and inflammatory mediators, and decreased levels of adiponectin all of which may impair endothelial insulin signaling. Microvascular dysfunction may thus constitute a new treatment target in the prevention of type 2 diabetes mellitus and hypertension.
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Affiliation(s)
- Ü Karaca
- Department of Internal Medicine and Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - M T Schram
- Department of Internal Medicine and Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - A J H M Houben
- Department of Internal Medicine and Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.
| | - D M J Muris
- Department of Internal Medicine and Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - C D A Stehouwer
- Department of Internal Medicine and Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
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Cornette J, Herzog E, Buijs EAB, Duvekot JJ, Rizopoulos D, Hop WCJ, Tibboel D, Steegers EAP. Microcirculation in women with severe pre-eclampsia and HELLP syndrome: a case-control study. BJOG 2013; 121:363-70. [PMID: 24206102 DOI: 10.1111/1471-0528.12475] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2013] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To compare microcirculatory perfusion in women with severe pre-eclampsia against that in healthy pregnant women, and secondly in women with severe pre-eclampsia with or without HELLP syndrome (haemolysis, elevated liver enzymes, and low platelets). DESIGN Case-control study. SETTING University Hospital Rotterdam, the Netherlands. POPULATION Twenty-three women with severe pre-eclampsia and 23 healthy pregnant controls, matched for maternal and gestational age. Out of the 23 women with severe pre-eclampsia, ten presented with HELLP syndrome. METHODS Microcirculation was analysed sublingually by a non-invasive sidestream dark-field imaging device (SDF). MAIN OUTCOME MEASURES Perfused vessel density (PVD), microcirculatory flow index (MFI), and heterogeneity index (HI) were calculated for both small vessels (∅ < 20 μm; capillaries) and non-small vessels (∅ > 20 μm; venules and arterioles). RESULTS There were no significant differences between women with severe pre-eclampsia and healthy controls. Women with pre-eclampsia and HELLP syndrome showed a reduced PVD (P = 0.045), MFI (P = 0.008), and increased HI (P = 0.002) for small vessels, as compared with women with pre-eclampsia but without HELLP syndrome. CONCLUSIONS Sidestream dark-field is a novel, promising technique in obstetrics that permits the non-invasive evaluation of microcirculation. We did not observe major differences in sublingual microcirculatory perfusion between women with severe pre-eclampsia and healthy pregnant controls. In women with severe pre-eclampsia, the presence of HELLP syndrome is characterised by impaired capillary perfusion.
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Affiliation(s)
- J Cornette
- Department of Obstetrics & Gynaecology, Division of Obstetrics & Prenatal Medicine, Sophia Children's Hospital, Rotterdam, The Netherlands
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Muris DMJ, Houben AJHM, Schram MT, Stehouwer CDA. Microvascular dysfunction: an emerging pathway in the pathogenesis of obesity-related insulin resistance. Rev Endocr Metab Disord 2013; 14:29-38. [PMID: 23299657 DOI: 10.1007/s11154-012-9231-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The prevalence of type 2 diabetes mellitus (T2DM) and its major risk factor, obesity, has reached epidemic proportions in Western society. How obesity leads to insulin resistance and subsequent T2DM is incompletely understood. It has been established that insulin can redirect blood flow in skeletal muscle from non-nutritive to nutritive capillary networks, without increasing total blood flow. This results in a net increase of the overall number of perfused nutritive capillary networks and thereby increases insulin-mediated glucose uptake by skeletal muscle. This process, referred to as functional (nutritive) capillary recruitment, has been shown to be endothelium-dependent and to require activation of the phosphatidylinositol-kinase (PI3K) pathway in the endothelial cell. Several studies have demonstrated that these processes are impaired in states of microvascular dysfunction. In obesity, changes in several adipokines are likely candidates to influence insulin signaling pathways in endothelial cells, thereby causing microvascular dysfunction. Microvascular dysfunction, in turn, impairs the timely access of glucose and insulin to their target tissues, and may therefore be an additional cause of insulin resistance. Thus, microvascular dysfunction may be a key feature in the development of obesity-related insulin resistance. In the present review, we will discuss the evidence for this emerging role for the microcirculation as a possible link between obesity and insulin resistance.
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Affiliation(s)
- Dennis M J Muris
- Department of Internal Medicine, Maastricht University Medical Centre (MUMC+), P.O. Box 5800, 6202 AZ, Maastricht, the Netherlands
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Demir SU, Hakimzadeh R, Hargraves RH, Ward KR, Myer EV, Najarian K. An automated method for analysis of microcirculation videos for accurate assessment of tissue perfusion. BMC Med Imaging 2012; 12:37. [PMID: 23259402 PMCID: PMC3560228 DOI: 10.1186/1471-2342-12-37] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 12/17/2012] [Indexed: 02/01/2023] Open
Abstract
Background Imaging of the human microcirculation in real-time has the potential to detect injuries and illnesses that disturb the microcirculation at earlier stages and may improve the efficacy of resuscitation. Despite advanced imaging techniques to monitor the microcirculation, there are currently no tools for the near real-time analysis of the videos produced by these imaging systems. An automated system tool that can extract microvasculature information and monitor changes in tissue perfusion quantitatively might be invaluable as a diagnostic and therapeutic endpoint for resuscitation. Methods The experimental algorithm automatically extracts microvascular network and quantitatively measures changes in the microcirculation. There are two main parts in the algorithm: video processing and vessel segmentation. Microcirculatory videos are first stabilized in a video processing step to remove motion artifacts. In the vessel segmentation process, the microvascular network is extracted using multiple level thresholding and pixel verification techniques. Threshold levels are selected using histogram information of a set of training video recordings. Pixel-by-pixel differences are calculated throughout the frames to identify active blood vessels and capillaries with flow. Results Sublingual microcirculatory videos are recorded from anesthetized swine at baseline and during hemorrhage using a hand-held Side-stream Dark Field (SDF) imaging device to track changes in the microvasculature during hemorrhage. Automatically segmented vessels in the recordings are analyzed visually and the functional capillary density (FCD) values calculated by the algorithm are compared for both health baseline and hemorrhagic conditions. These results were compared to independently made FCD measurements using a well-known semi-automated method. Results of the fully automated algorithm demonstrated a significant decrease of FCD values. Similar, but more variable FCD values were calculated using a commercially available software program requiring manual editing. Conclusions An entirely automated system for analyzing microcirculation videos to reduce human interaction and computation time is developed. The algorithm successfully stabilizes video recordings, segments blood vessels, identifies vessels without flow and calculates FCD in a fully automated process. The automated process provides an equal or better separation between healthy and hemorrhagic FCD values compared to currently available semi-automatic techniques. The proposed method shows promise for the quantitative measurement of changes occurring in microcirculation during injury.
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Donndorf P, Kühn F, Vollmar B, Rösner J, Liebold A, Gierer P, Steinhoff G, Kaminski A. Comparing microvascular alterations during minimal extracorporeal circulation and conventional cardiopulmonary bypass in coronary artery bypass graft surgery: A prospective, randomized study. J Thorac Cardiovasc Surg 2012; 144:677-83. [DOI: 10.1016/j.jtcvs.2012.05.037] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 04/04/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
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Možina H, Podbegar M. Near-infrared spectroscopy for evaluation of global and skeletal muscle tissue oxygenation. World J Cardiol 2011; 3:377-82. [PMID: 22216373 PMCID: PMC3247683 DOI: 10.4330/wjc.v3.i12.377] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 11/17/2011] [Accepted: 11/20/2011] [Indexed: 02/06/2023] Open
Abstract
Non-invasive clinical examination has well-recognized limitations in detecting compensated and uncompensated low flow states and their severity. This paper describes the principles of near-infrared absorption spectroscopy (NIRS) and the basis for its proposed use in heart failure/cardiogenic and septic shock to assess global and regional tissue oxygenation. The vascular occlusion test is explained. Limitations of NIRS, current controversies, and what is necessary in the future to make this technology a part of the initial and ongoing assessment of a patient are also discussed. The ultimate goal of such techniques is to prevent miss-assessment and inadequate resuscitation of patients, two major factors in the development of multisystem organ failure and death.
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Affiliation(s)
- Hugon Možina
- Hugon Možina, Department of Emergency, University Medical Centre Ljubljana, Ljubljana SI-1000, Slovenia
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Perivascular Fat and the Microcirculation: Relevance to Insulin Resistance, Diabetes, and Cardiovascular Disease. CURRENT CARDIOVASCULAR RISK REPORTS 2011; 6:80-90. [PMID: 22247785 PMCID: PMC3251783 DOI: 10.1007/s12170-011-0214-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Type 2 diabetes and its major risk factor, obesity, are a growing burden for public health. The mechanisms that connect obesity and its related disorders, such as insulin resistance, type 2 diabetes, and hypertension, are still undefined. Microvascular dysfunction may be a pathophysiologic link between insulin resistance and hypertension in obesity. Many studies have shown that adipose tissue-derived substances (adipokines) interact with (micro)vascular function and influence insulin sensitivity. In the past, research focused on adipokines from perivascular adipose tissue (PVAT). In this review, we focus on the interactions between adipokines, predominantly from PVAT, and microvascular function in relation to the development of insulin resistance, diabetes, and cardiovascular disease.
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Ergenekon E, Hirfanoglu IM, Turan O, Beken S, Gucuyener K, Atalay Y. Partial exchange transfusion results in increased cerebral oxygenation and faster peripheral microcirculation in newborns with polycythemia. Acta Paediatr 2011; 100:1432-6. [PMID: 21595746 DOI: 10.1111/j.1651-2227.2011.02358.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM The aim of this study was to assess cerebral and peripheral oxygenation, by using near infrared spectroscopy (NIRS) and microcirculation by using side stream dark field (SDF) imaging in newborns with polycythemia before and after partial exchange transfusion (PET) therapy to investigate treatment effect on tissue oxygenation and microcirculation. METHODS Polycythemic newborns with venous haematocrit (Htc) >70% or ≥65% with symptoms were included. NIRS measurements for cerebral and peripheral oxygenation and SDF recordings for microcirculatory flow assessment were obtained before and after PET. Fractional tissue oxygen extraction (FTOE) was calculated based on tissue oxygenation index and oxygen saturation. Wilcoxon test was used for statistical analysis. RESULTS Fifteen newborns were included. Cerebral tissue oxygenation index, microvascular flow index and % of vessels with hyperdynamic flow increased after PET; median (range): 61.27 (51.36-61.87) versus 64.54 (54.1-74.38), 2.74 (2.46-3) versus 3.22 (2.64-3.75) and 0 (0-2.8) versus 3 (0-99.3), respectively. Whereas cerebral fractional tissue oxygen extraction (CFTOE), % of vessels with sluggish flow decreased after treatment; 0.36 (0.22-0.44) versus 0.31 (0.17-0.46), 1.4 (0-69) versus 0 (0-0.9), respectively. Peripheral oxygenation was unchanged. CONCLUSION Partial exchange transfusion improves microcirculation in polycythemic newborns. Cerebral oxygenation increases and cFTOE decreases suggesting increased blood flow. Microvascular flow increases possibly representing reactive hyperperfusion after hemodilution. Whether these effects are beneficial require further research.
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Affiliation(s)
- Ebru Ergenekon
- Division of Newborn Medicine, Department of Pediatrics, Gazi University Hospital, Ankara, Turkey.
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Pinaud F, Loufrani L, Toutain B, Lambert D, Vandekerckhove L, Henrion D, Baufreton C. In vitro protection of vascular function from oxidative stress and inflammation by pulsatility in resistance arteries. J Thorac Cardiovasc Surg 2011; 142:1254-62. [DOI: 10.1016/j.jtcvs.2011.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 04/23/2011] [Accepted: 07/11/2011] [Indexed: 11/30/2022]
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Gonçalves-Pereira J, Póvoa P. Antibiotics in critically ill patients: a systematic review of the pharmacokinetics of β-lactams. Crit Care 2011; 15:R206. [PMID: 21914174 PMCID: PMC3334750 DOI: 10.1186/cc10441] [Citation(s) in RCA: 287] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 06/28/2011] [Accepted: 09/13/2011] [Indexed: 01/02/2023] Open
Abstract
INTRODUCTION Several reports have shown marked heterogeneity of antibiotic pharmacokinetics (PK) in patients admitted to ICUs, which might potentially affect outcomes. Therefore, the pharmacodynamic (PD) parameter of the efficacy of β-lactam antibiotics, that is, the time that its concentration is above the bacteria minimal inhibitory concentration (T > MIC), cannot be safely extrapolated from data derived from the PK of healthy volunteers. METHODS We performed a full review of published studies addressing the PK of intravenous β-lactam antibiotics given to infected ICU patients. Study selection comprised a comprehensive bibliographic search of the PubMed database and bibliographic references in relevant reviews from January 1966 to December 2010. We selected only English-language articles reporting studies addressing β-lactam antibiotics that had been described in at least five previously published studies. Studies of the PK of patients undergoing renal replacement therapy were excluded. RESULTS A total of 57 studies addressing six different β-lactam antibiotics (meropenem, imipenem, piperacillin, cefpirome, cefepime and ceftazidime) were selected. Significant PK heterogeneity was noted, with a broad, more than twofold variation both of volume of distribution and of drug clearance (Cl). The correlation of antibiotic Cl with creatinine clearance was usually reported. Consequently, in ICU patients, β-lactam antibiotic half-life and T > MIC were virtually unpredictable, especially in those patients with normal renal function. A better PD profile was usually obtained by prolonged or even continuous infusion. Tissue penetration was also found to be compromised in critically ill patients with septic shock. CONCLUSIONS The PK of β-lactam antibiotics are heterogeneous and largely unpredictable in ICU patients. Consequently, the dosing of antibiotics should be supported by PK concepts, including data derived from studies of the PK of ICU patients and therapeutic drug monitoring.
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Affiliation(s)
- Joao Gonçalves-Pereira
- Polyvalent Intensive Care Unit, São Francisco Xavier Hospital, Estrada do Forte do Alto do Duque, 1449-005 Lisboa, Portugal
- CEDOC, Faculty of Medical Sciences, New University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056 Lisboa, Portugal
| | - Pedro Póvoa
- Polyvalent Intensive Care Unit, São Francisco Xavier Hospital, Estrada do Forte do Alto do Duque, 1449-005 Lisboa, Portugal
- CEDOC, Faculty of Medical Sciences, New University of Lisbon, Campo dos Mártires da Pátria, 130, 1169-056 Lisboa, Portugal
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Error in noninvasive spectrophotometric measurement of blood hemoglobin concentration under conditions of blood loss. Med Hypotheses 2011; 77:665-7. [PMID: 21820812 DOI: 10.1016/j.mehy.2011.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Revised: 07/01/2011] [Accepted: 07/04/2011] [Indexed: 11/22/2022]
Abstract
This paper discusses a current misinterpretation between different parameters of hemoglobin concentration measurement and its amplification under conditions of blood loss. The paper details the distinction between microcirculatory hematocrit and the hematocrit of the macrocirculation to analyze clinical use of real-time patient hemoglobin concentration measurement by noninvasive point-of-care devices such as the Rainbow Pulse CO-Oximetry™ (Masimo Corp., Irvine, CA). The hemoglobin concentration or hematocrit values have clinical significance such as for diagnosing anemia or as indicators to when a blood transfusion is needed. The device infers hemoglobin concentration from spectrophotometry of the fingertip and therefore the measured absorption is due to hemoglobin present in capillaries as well as in larger vessels, and the device accordingly reports the hemoglobin concentration as 'total hemoglobin' in a proprietary SpHb parameter. SpHb and macro hemoglobin concentration are different parameters. However, the numerical resemblance of SpHb values to values of macro hemoglobin concentrations, combined with the widely used unspecified term "Hb" in the medical setting, suggests that SpHb values are often interpreted by the clinician as macro hematocrit values. The claim of this paper is that under conditions of blood loss the portion of the SpHb total hemoglobin measure that is contributed from microcirculation increases, due to the decrease of macro hematocrit while microcirculatory hematocrit remains constant when above a critical value. The device is calibrated from phlembotomy drawn blood (from a vein in the arm), which is the gold standard in blood collection, and hence this changing contribution of microcirculatory hemoglobin to the SpHb value would distort the gap between macro hemoglobin and total hemoglobin, SpHb. The hypothesis is that if clinicians indeed interpret the SpHb values as macro hemoglobin values then there is an unreported discrepancy between SpHb to macro hemoglobin concentrations during blood loss due to the increasing effect of microcirculatory hemoglobin measurement on the mixed parameter, SpHb.
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Chen PC, Lin WC. Spectral-profile-based algorithm for hemoglobin oxygen saturation determination from diffuse reflectance spectra. BIOMEDICAL OPTICS EXPRESS 2011; 2:1082-96. [PMID: 21559121 PMCID: PMC3087566 DOI: 10.1364/boe.2.001082] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 03/29/2011] [Accepted: 04/01/2011] [Indexed: 05/26/2023]
Abstract
Variations of hemoglobin (Hb) oxygenation in tissue provide important indications concerning the physiological conditions of tissue, and the data related to these variations are of intense interest in medical research as well as in clinical care. In this study, we derived a new algorithm to estimate Hb oxygenation from diffuse reflectance spectra. The algorithm was developed based on the unique spectral profile differences between the extinction coefficient spectra of oxy-Hb and deoxy-Hb within the visible wavelength region. Using differential wavelet transformation, these differences were quantified using the locations of certain spectral features, and, then, they were related to the oxygenation saturation level of Hb. The applicability of the algorithm was evaluated using a set of diffuse reflectance spectra produced by a Monte Carlo simulation model of photon migration and by tissue phantoms experimentally. The algorithm was further applied to the diffuse reflectance spectra acquired from in vivo experiments to demonstrate its clinical utility. The validation and evaluation results concluded that the algorithm is applicable to various tissue types (i.e., scattering properties) and can be easily used in conjunction with a diverse range of probe geometries for real-time monitoring of Hb oxygenation.
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Affiliation(s)
- Po-Ching Chen
- Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, EAS 2673, Miami, Florida 33176, USA
| | - Wei-Chiang Lin
- Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, EAS 2673, Miami, Florida 33176, USA
- Brain Institute, Miami Children’s Hospital, 3100 SW 62 Ave, Miami, FL 33155, USA
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Peruski AM, Cooper ES. Assessment of microcirculatory changes by use of sidestream dark field microscopy during hemorrhagic shock in dogs. Am J Vet Res 2011; 72:438-45. [DOI: 10.2460/ajvr.72.4.438] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
OBJECTIVE To investigate whether the pleth variability index, a noninvasive and continuous tool, can predict fluid responsiveness in mechanically ventilated patients with circulatory insufficiency. DESIGN Prospective study. SETTING Surgical intensive care unit of a university hospital. PATIENTS Forty mechanically ventilated patients with circulatory insufficiency in whom volume expansion was planned by attending physician. Exclusion criteria included spontaneous respiratory activity, cardiac arrhythmia, known intracardiac shunt, severe hypoxemia (Pao2/Fio2 <100 mm Hg), contraindication for passive leg raising, left ventricular ejection fraction of <50%, and hemodynamic instability during the procedure. INTERVENTIONS Fluid challenge with 500 mL of 130/0.4 hydroxyethyl-starch if respiratory variations in arterial pulse pressure were ≥ 13% or with passive leg raising if variations in arterial pulse pressure were <13%. MEASUREMENTS AND MAIN RESULTS Pleth variability index, variations in arterial pulse pressure, and cardiac output estimated by echocardiography were recorded before and after fluid challenge. Fluid responsiveness was defined as an increase in cardiac output of ≥ 15%. Twenty-one patients were responders and 19 were nonresponders. Mean ± sd pleth variability index (28% ± 13% vs. 11% ± 4%) and arterial pulse pressure variation (22% ± 11% vs. 5% ± 2%) values at baseline were significantly higher in responders than in nonresponders. The pleth variability index threshold value of 17% allowed discrimination between responders and nonresponders with a sensitivity of 95% (95% confidence interval, 74% to 100%) and a specificity of 91% (95% confidence interval, 70% to 99%). The pleth variability index at baseline correlated (r = .72, p < .0001) with the percentage change in cardiac output induced by fluid challenge, suggesting that a higher pleth variability index at baseline will correlate with a higher percentage change in cardiac output after volume expansion. CONCLUSIONS The pleth variability index can predict fluid responsiveness noninvasively in intensive care unit patients under mechanical ventilation.
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Nacul FE, Guia IL, Lessa MA, Tibiriçá E. The Effects of Vasoactive Drugs on Intestinal Functional Capillary Density in Endotoxemic Rats: Intravital Video-Microscopy Analysis. Anesth Analg 2010; 110:547-54. [DOI: 10.1213/ane.0b013e3181c88af1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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[Microcirculatory alterations in critically ill patients: pathophysiology, monitoring and treatments]. ACTA ACUST UNITED AC 2010; 29:135-44. [PMID: 20116198 DOI: 10.1016/j.annfar.2009.10.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Accepted: 10/28/2009] [Indexed: 01/18/2023]
Abstract
Microcirculation represents a complex system devoted to provide optimal tissue substrates and oxygen. Therefore, pathophysiological and technological knowledge developments tailored for capillary circulation analysis should generate major advances for critically ill patients' management. In the future, microcirculatory monitoring in several critical care situations will allow recognition of macro-microcirculatory decoupling, and, hopefully, it will promote the use of treatments aimed at preserving tissue oxygenation and substrate delivery.
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Ruiz C, Hernandez G, Ince C. Diagnosis and Treatment of the Septic Microcirculation. Intensive Care Med 2010. [DOI: 10.1007/978-1-4419-5562-3_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Evaluation of sublingual and gut mucosal microcirculation in sepsis: a quantitative analysis. Crit Care Med 2009; 37:2875-81. [PMID: 19770750 DOI: 10.1097/ccm.0b013e3181b029c1] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
OBJECTIVE To determine the relationship between sublingual and intestinal mucosal microcirculatory perfusion. DESIGN Observational, experimental study. SETTING University-affiliated large animal laboratory. SUBJECTS Ten fasted, anesthetized, mechanically ventilated, male pigs randomized to a sham group (n = 3) or to a hyperdynamic septic shock group (n = 7) in which cholangitis was induced by direct infusion of Escherichia coli into the common bile duct. This model was developed because it is not accompanied by changes in intra-abdominal pressure. MEASUREMENTS AND MAIN RESULTS The sublingual and intestinal microcirculations were simultaneously assessed at 4-hr intervals for up to 12 hrs with a modified orthogonal polarization spectral device and functional microvessel density and erythrocyte velocity were measured quantitatively. In sham animals, both regions maintained a stable functional microvessel density and erythrocyte velocity throughout the study period. In contrast, in septic animals, already after 4 hrs of sepsis, functional microvessel density was markedly decreased (>50%) in the sublingual and gut regions; mean erythrocyte velocity decreased dramatically and similarly in both regions, from 1022 +/- 80 to 265 +/- 43 mum/sec in the sublingual region and from 1068 +/- 45 to 243 +/- 115 mum/sec in the gut (p < 0.001, at T12). There was a significant correlation between the sublingual and gut microcirculations in septic animals (r = 0.92, p < 0.0001). CONCLUSIONS The severity and the time course of microcirculatory changes were similar in the sublingual and in the gut region in this clinically relevant model of severe sepsis. These findings support the sublingual region as an appropriate region to monitor the microcirculation in sepsis.
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Nencioni A, Trzeciak S, Shapiro NI. The microcirculation as a diagnostic and therapeutic target in sepsis. Intern Emerg Med 2009; 4:413-8. [PMID: 19707845 DOI: 10.1007/s11739-009-0297-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 07/17/2009] [Indexed: 01/08/2023]
Abstract
The microcirculation is defined as the smallest vessels where gas and nutrient exchange with tissues takes place. One of its primary functions is to ensure adequate oxygen delivery to meet the oxygen demands of tissue cells. Previous data from clinical and experimental studies and the recent development of new imaging modalities, such as Orthogonal Polarization Spectral videomicroscopy and Sidestream Dark Field imaging, have helped to identify the crucial role that microcirculation plays in sepsis. If not corrected, microcirculatory dysfunction can lead to respiratory distress in tissue cells and subsequent organ failure, even in the absence of global hemodynamic deficiency. In the present review, we will address past and recent developments regarding the role of the microcirculation as an important target in the pathogenesis of sepsis and its progression to multiple organ failure. Accordingly, we identify the microcirculation as an important diagnostic and therapeutic target for treatment in sepsis.
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Affiliation(s)
- Andrea Nencioni
- Department of Surgical and Medical Critical Care, University of Florence, Florence, Italy
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Abstract
Key links in the chain of survival for the management of severe sepsis and septic shock are early identification and comprehensive resuscitation of high-risk patients. Multiple studies have shown that the first 6 hours of early sepsis management are especially important from a diagnostic, pathogenic, and therapeutic perspective, and that steps taken during this period can have a significant impact on outcome. The recognition of this critical time period and the robust outcome benefit realized in previous studies provides the rationale for adopting early resuscitation as a distinct intervention. Sepsis joins trauma, stroke, and acute myocardial infarction in having "golden hours," representing a critical opportunity early on in the course of disease for actions that offer the most benefit.
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Sheikh MY, Javed U, Singh J, Choudhury J, Deen O, Dhah K, Peterson MW. Bedside sublingual video imaging of microcirculation in assessing bacterial infection in cirrhosis. Dig Dis Sci 2009; 54:2706-11. [PMID: 19117129 PMCID: PMC2778688 DOI: 10.1007/s10620-008-0664-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 12/08/2008] [Indexed: 12/29/2022]
Abstract
Bacterial infections are common in cirrhosis and can lead to life-threatening complications. Sidestream dark-field (SDF) imaging has recently emerged as a noninvasive tool for capturing real-time video images of sublingual microcirculation in critically ill patients with sepsis. The objective of this study was to assess the utility of SDF in determining underlying infection in patients with cirrhosis. Sublingual microcirculation was compared among patients with compensated cirrhosis (Group A, n=13), cirrhosis without sepsis (Group B, n=18), cirrhosis with sepsis (Group C, n=14), and sepsis only (Group D, n=10). The blood flow was semi-quantitatively evaluated in four equal quadrants in small (10-25 mm); medium (26-50 mm); and large (51-100 mm) sublingual capillaries. The blood flow was described as no flow (0), intermittent flow (1), sluggish flow (2), and continuous flow (3). The overall flow score or microvascular flow index (MFI) was measured for quantitative assessment of microcirculation and predicting power for concurrent infection in cirrhosis. Marked impairment was observed at all levels of microvasculature in Groups B and C when compared with Group A. This effect was restricted to small vessels only when Group B was compared with Group C. MFI<1.5 was found to have highest sensitivity (100%) and specificity (100%) for infection in decompensated cirrhosis. SDF imaging of sublingual microcirculation can be a useful bedside diagnostic tool to assess bacterial infection in cirrhosis.
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Affiliation(s)
- Muhammad Y. Sheikh
- Division of Gastroenterology and Hepatology, University of California San Francisco-Fresno Medical Education Program, Community Regional Medical Center, 2823 Fresno Street, 1st Floor, Endoscopy Suite, Fresno, CA 93721 USA
| | - Usman Javed
- Division of Cardiology, University of California San Francisco-Fresno Medical Education Program, Fresno, CA USA
| | - Jasjit Singh
- Department of Internal Medicine, University of California San Francisco-Fresno Medical Education Program, Fresno, CA USA
| | - Jayanta Choudhury
- Division of Gastroenterology and Hepatology, University of California San Francisco-Fresno Medical Education Program, Community Regional Medical Center, 2823 Fresno Street, 1st Floor, Endoscopy Suite, Fresno, CA 93721 USA
| | - Omer Deen
- Division of Gastroenterology and Hepatology, University of California San Francisco-Fresno Medical Education Program, Community Regional Medical Center, 2823 Fresno Street, 1st Floor, Endoscopy Suite, Fresno, CA 93721 USA
| | - Kulraj Dhah
- Division of Gastroenterology and Hepatology, University of California San Francisco-Fresno Medical Education Program, Community Regional Medical Center, 2823 Fresno Street, 1st Floor, Endoscopy Suite, Fresno, CA 93721 USA
| | - Michael W. Peterson
- Department of Internal Medicine, University of California San Francisco-Fresno Medical Education Program, Fresno, CA USA
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Ellender TJ, Skinner JC. The Use of Vasopressors and Inotropes in the Emergency Medical Treatment of Shock. Emerg Med Clin North Am 2008; 26:759-86, ix. [DOI: 10.1016/j.emc.2008.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Abstract
Left untreated, third-spacing can lead to serious complications. Here's what you need to know to get your patient back in balance.
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Jonk AM, Houben AJHM, de Jongh RT, Serné EH, Schaper NC, Stehouwer CDA. Microvascular dysfunction in obesity: a potential mechanism in the pathogenesis of obesity-associated insulin resistance and hypertension. Physiology (Bethesda) 2007; 22:252-60. [PMID: 17699878 DOI: 10.1152/physiol.00012.2007] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Obesity is an important risk factor for insulin resistance and hypertension and plays a central role in the metabolic syndrome. Insight into the pathophysiology of this syndrome may lead to new treatments. This paper has reviewed the evidence for an important role for the microcirculation as a possible link between obesity, insulin resistance and hypertension.
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Affiliation(s)
- Amy M Jonk
- Department of Internal Medicine, University Hospital Maastricht, and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
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Knotzer H, Hasibeder WR. Microcirculatory function monitoring at the bedside--a view from the intensive care. Physiol Meas 2007; 28:R65-86. [PMID: 17827646 DOI: 10.1088/0967-3334/28/9/r01] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Microcirculatory dysfunction plays a key role in the pathophysiology of various disease states and may consequently impact patient outcome. Until recently, the evaluation of the microcirculation using different measurement techniques has been mostly limited to animal and human research. With technical advances, microcirculatory monitoring nowadays becomes more and more available for application in clinical praxis. Unfortunately, measurements within the microcirculation are mostly limited to easily accessible surfaces, such as skin, muscle and tongue. Due to major differences in the physiologic regulation of microcirculatory blood flow and in metabolism between organs and even within different tissues in one organ, the clinical importance of regional microcirculatory measurements remains to be determined. In addition, technical methods available demonstrate large differences in the measured parameters and sampling volume, making interpretation of data even more difficult. Nonetheless, the monitoring of the microcirculation may, ahead of time, alert physicians that tissue oxygen supply becomes compromised and it may lead to a better understanding of basic pathophysiological aspects of disease. In the present review, we describe available non-invasive microcirculatory measurement techniques which can be applied clinically at the bedside. After a short discussion of physiologic and pathophysiologic basics related to microcirculatory monitoring, the measuring principles, applications, strengths and limitations of different monitoring systems are discussed.
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Affiliation(s)
- Hans Knotzer
- Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.
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Büchele GL, Ospina-Tascon GA, De Backer D. How microcirculation data have changed my clinical practice. Curr Opin Crit Care 2007; 13:324-31. [PMID: 17468566 DOI: 10.1097/mcc.0b013e3280c1e5c5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The present review discusses how microcirculation assessment, which was recently made feasible, has altered clinical practice. RECENT FINDINGS Experimental data have provided important information on microcirculation alterations in disease states. Recent advances in imaging techniques have allowed microcirculation studies in critically ill patients. Derangements in microcirculation are variable and unpredictable, associated with organ dysfunction and outcome, and can be improved by therapeutic interventions. Recent studies not only confirm the beneficial effects of some drugs on the microcirculation, but also suggest new mechanisms of actions of these drugs. In particular, the interaction between the endothelial surface and circulating cells, and especially white blood cells, seems to be crucial. Although these imaging techniques provide important information, these remain difficult to implement at the bedside. Assessment of vasoreactivity using transient occlusion tests and indirect measurements of microvascular blood flow with laser Doppler or near infrared spectroscopy may be good alternatives. SUMMARY Microcirculation alterations are present in shock states, mainly septic shock, and can have a prognostic role and be the target of therapeutic interventions. To date, microcirculation analysis remains in the field of clinical investigation, but recently interesting clinical data have encouraged assessment of the microcirculation at the bedside.
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Affiliation(s)
- Gustavo Luiz Büchele
- Department of Intensive Care, Erasme University Hospital, Free University of Brussels, Belgium
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Podbregar M, Možina H. Skeletal muscle oxygen saturation does not estimate mixed venous oxygen saturation in patients with severe left heart failure and additional severe sepsis or septic shock. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2007; 11:R6. [PMID: 17227587 PMCID: PMC2147710 DOI: 10.1186/cc5153] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 11/30/2006] [Accepted: 01/16/2007] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Low cardiac output states such as left heart failure are characterized by preserved oxygen extraction ratio, which is in contrast to severe sepsis. Near infrared spectroscopy (NIRS) allows noninvasive estimation of skeletal muscle tissue oxygenation (StO2). The aim of the study was to determine the relationship between StO2 and mixed venous oxygen saturation (SvO2) in patients with severe left heart failure with or without additional severe sepsis or septic shock. METHODS Sixty-five patients with severe left heart failure due to primary heart disease were divided into two groups: groups A (n = 24) and B (n = 41) included patients without and with additional severe sepsis/septic shock, respectively. Thenar muscle StO2 was measured using NIRS in the patients and in 15 healthy volunteers. RESULTS StO2 was lower in group A than in group B and in healthy volunteers (58 +/- 13%, 90 +/- 7% and 84 +/- 4%, respectively; P < 0.001). StO2 was higher in group B than in healthy volunteers (P = 0.02). In group A StO2 correlated with SvO2 (r = 0.689, P = 0.002), although StO2 overestimated SvO2 (bias -2.3%, precision 4.6%). In group A changes in StO2 correlated with changes in SvO2 (r = 0.836, P < 0.001; DeltaSvO2 = 0.84 x DeltaStO2 - 0.67). In group B important differences between these variables were observed. Plasma lactate concentrations correlated negatively with StO2 values only in group A (r = -0.522, P = 0.009; lactate = -0.104 x StO2 + 10.25). CONCLUSION Skeletal muscle StO2 does not estimate SvO2 in patients with severe left heart failure and additional severe sepsis or septic shock. However, in patients with severe left heart failure without additional severe sepsis or septic shock, StO2 values could be used to provide rapid, noninvasive estimation of SvO2; furthermore, the trend in StO2 may be considered a surrogate for the trend in SvO2.
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Affiliation(s)
- Matej Podbregar
- Clinical Department for Intensive Care Medicine, University Clinical Centre, Zaloska 7, 1000 Ljubljana, Slovenia
| | - Hugon Možina
- Clinical Department for Intensive Care Medicine, University Clinical Centre, Zaloska 7, 1000 Ljubljana, Slovenia
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Samuelsson A, Steinvall I, Sjöberg F. Microdialysis shows metabolic effects in skin during fluid resuscitation in burn-injured patients. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2007; 10:R172. [PMID: 17166287 PMCID: PMC1794489 DOI: 10.1186/cc5124] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 10/31/2006] [Accepted: 12/13/2006] [Indexed: 01/04/2023]
Abstract
INTRODUCTION Established fluid treatment formulas for burn injuries have been challenged as studies have shown the presence of tissue hypoxia during standard resuscitation. Such findings suggest monitoring at the tissue level. This study was performed in patients with major burn injuries to evaluate the microdialysis technique for the continuous assessment of skin metabolic changes during fluid resuscitation and up to four days postburn. METHODS We conducted an experimental study in patients with a burn injury, as represented by percentage of total body surface area burned (TBSA), of more than 25% in a university eight-bed burns intensive care unit serving about 3.5 million inhabitants. Six patients with a median TBSA percentage of 59% (range 33.5% to 90%) and nine healthy controls were examined by intracutaneous MD, in which recordings of glucose, pyruvate, lactate, glycerol, and urea were performed. RESULTS Blood glucose concentration peaked on day two at 9.8 mmol/l (6.8 to 14.0) (median and range) and gradually declined on days three and four, whereas skin glucose in MD continued to increase throughout the study period with maximum values on day four, 8.7 mmol/l (4.9 to 11.0). Controls had significantly lower skin glucose values compared with burn patients, 3.1 mmol/l (1.5 to 4.6) (p < 0.001). Lactate from burn patients was significantly higher than controls in both injured and uninjured skin (MD), 4.6 mmol/l (1.3 to 8.9) and 3.8 mmol/l (1.6 to 7.5), respectively (p < 0.01). The skin lactate/pyruvate ratio (MD) was significantly increased in burn patients on all days (p < 0.001). Skin glycerol (MD) was significantly increased at days three and four in burn patients compared with controls (p < 0.01). CONCLUSION Despite a strategy that fulfilled conventional goals for resuscitation, there were increased lactate/pyruvate ratios, indicative of local acidosis. A corresponding finding was not recorded systemically. We conclude that MD is a promising tool for depicting local metabolic processes that are not fully appreciated when examined systemically. Because the local response in glucose, lactate, and pyruvate metabolism seems to differ from that recorded systemically, this technique may offer a new method of monitoring organs.
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Affiliation(s)
- Anders Samuelsson
- Department of Intensive Care, Linköping University Hospital, 581 85 Linköping, Sweden
| | - Ingrid Steinvall
- The Burn Unit, Department of Hand and Plastic Surgery, Linköping University Hospital, 581 85 Linköping, Sweden
| | - Folke Sjöberg
- Department of Intensive Care, Linköping University Hospital, 581 85 Linköping, Sweden
- The Burn Unit, Department of Hand and Plastic Surgery, Linköping University Hospital, 581 85 Linköping, Sweden
- Faculty of Health Sciences, Department of Biomedicine and Surgery, Linköping University Hospital, 581 85 Linköping, Sweden
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McKay JC, Prato FS, Thomas AW. A literature review: The effects of magnetic field exposure on blood flow and blood vessels in the microvasculature. Bioelectromagnetics 2007; 28:81-98. [PMID: 17004242 DOI: 10.1002/bem.20284] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effect of magnetic field (MF) exposure on microcirculation and microvasculature is not clear or widely explored. In the limited body of data that exists, there are contradictions as to the effects of MFs on blood perfusion and pressure. Approximately half of the cited studies indicate a vasodilatory effect of MFs; the remaining half indicate that MFs could trigger either vasodilation or vasoconstriction depending on initial vessel tone. Few studies indicate that MFs cause a decrease in perfusion or no effect. There is a further lack of investigation into the cellular effects of MFs on microcirculation and microvasculature. The role of nitric oxide (NO) in mediating microcirculatory MF effects has been minimally explored and results are mixed, with four studies supporting an increase in NO activity, one supporting a biphasic effect, and five indicating no effect. MF effects on angiogenesis are also reported: seven studies supporting an increase and two a decrease. Possible reasons for these contradictions are explored. This review also considers the effects of magnetic resonance imaging (MRI) and anesthetics on microcirculation. Recommendations for future work include studies aimed at the cellular/mechanistic level, studies involving perfusion measurements both during and post-exposure, studies testing the effect of MFs on anesthetics, and investigation into the microcirculatory effects of MRI.
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Affiliation(s)
- Julia C McKay
- Bioelectromagnetics, Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
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42
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van der Hoven B, Gommers D, Bakker J. Critical Illness and the Hepatic Microcirculation: A Review. Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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van der Hoven B, Gommers D, Bakker J. Critical Illness and the Hepatic Microcirculation: A Review. YEARBOOK OF INTENSIVE CARE AND EMERGENCY MEDICINE 2007. [DOI: 10.1007/978-3-540-49433-1_57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Boldt J. Fluid management of patients undergoing abdominal surgery – more questions than answers *. Eur J Anaesthesiol 2006; 23:631-40. [PMID: 16723057 DOI: 10.1017/s026502150600069x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2006] [Indexed: 11/06/2022]
Abstract
The 'wet vs. dry' philosophy in patients undergoing abdominal surgery is a subject of substantial debate. It has been suggested that restricting fluid input would significantly reduce complications and improve outcome following abdominal surgery. Keeping the patients dry may be a two-edged sword because the resulting hypovolaemia may result in compromised organ perfusion and poor tissue oxygenation. A review of the literature from 1990 to 2004 revealed that only very few studies on this subject have been published. Unfortunately, most of the 'dry'-supporting studies used fixed amounts of volume instead of a fluid concept adapted to the patients' need ('goal-directed') and there is no generally accepted definition of 'restricted', 'dry' or 'overload'. Not only the amount but also the kind of administered fluid appears to be important. Current evidence indicates that using crystalloids exclusively may cause overloading of the interstitial compartment with considerable negative sequelae, whereas using colloids may improve microperfusion and tissue oxygenation. This review shows that the meagre literature on a restricted volume replacement strategy in abdominal surgery patients cannot clearly support the 'dry' approach. Further well-performed studies are necessary to elucidate the ideal amount and type of fluid replacement and determine how to guide fluid therapy.
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Affiliation(s)
- J Boldt
- Klinikum der Stadt Ludwigshafen, Department of Anesthesiology and Intensive Care Medicine, Ludwigshafen, Germany.
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Brown KA, Brain SD, Pearson JD, Edgeworth JD, Lewis SM, Treacher DF. Neutrophils in development of multiple organ failure in sepsis. Lancet 2006; 368:157-69. [PMID: 16829300 DOI: 10.1016/s0140-6736(06)69005-3] [Citation(s) in RCA: 481] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Multiple organ failure is a major threat to the survival of patients with sepsis and systemic inflammation. In the UK and in the USA, mortality rates are currently comparable with and projected to exceed those from myocardial infarction. The immune system combats microbial infections but, in severe sepsis, its untoward activity seems to contribute to organ dysfunction. In this Review we propose that an inappropriate activation and positioning of neutrophils within the microvasculature contributes to the pathological manifestations of multiple organ failure. We further suggest that targeting neutrophils and their interactions with blood vessel walls could be a worthwhile therapeutic strategy for sepsis.
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Affiliation(s)
- K A Brown
- Division of Medical Education, King's College School of Medicine, London, UK.
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Buerger C, Plock N, Dehghanyar P, Joukhadar C, Kloft C. Pharmacokinetics of unbound linezolid in plasma and tissue interstitium of critically ill patients after multiple dosing using microdialysis. Antimicrob Agents Chemother 2006; 50:2455-63. [PMID: 16801426 PMCID: PMC1489800 DOI: 10.1128/aac.01468-05] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2005] [Revised: 02/20/2006] [Accepted: 04/28/2006] [Indexed: 11/20/2022] Open
Abstract
The antimicrobial agent linezolid is approved for the treatment of severe infections caused by, e.g., methicillin-resistant Staphylococcus strains. In order to evaluate the penetration of linezolid into the interstitial space fluid (ISF) of subcutaneous adipose tissue and skeletal muscle of the target population, a microdialysis study was performed with 12 patients with sepsis or septic shock after multiple intravenous infusions. Unbound linezolid concentrations were determined for plasma and microdialysates by use of a validated high-performance liquid chromatography method. Individual compartmental pharmacokinetic (PK) analysis was performed using WinNonlin. In vivo microdialysis was found to be feasible for the determination of unbound linezolid concentrations at steady state in the ISF of critically ill patients. On average, linezolid showed good distribution into ISF but with high interindividual variability. A two-compartment model was fitted to unbound concentrations in plasma with a geometric mean distribution volume of 62.9 liters and a mean clearance of 9.18 liters/h at steady state. However, disposition characteristics changed intraindividually within the time course. In addition, an integrated model for simultaneous prediction of concentrations in all matrices was developed and revealed similar results. Based on the model-predicted unbound concentrations in ISF, a scheme of more-frequent daily dosing of linezolid for some critically ill patients might be taken into consideration to avoid subinhibitory unbound concentrations in the infected tissue. The developed integrated model will be a valuable basis for further PK data analysis to explore refined dosing guidelines that achieve effective antimicrobial therapy in all patients by use of the population PK approach.
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Affiliation(s)
- Cornelia Buerger
- Department of Clinical Pharmacy, Institute of Pharmacy, Freie Universitaet Berlin, D-12169 Berlin, Germany
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Abstract
Microcirculatory dysfunctions play a central role in the pathophysiology of sepsis and shock. Modern methods enable microvascular monitoring in man and offer the possibility to test the effect of novel therapeutical strategies for sepsis. Furthermore, these techniques may be future tools for the monitoring of critically ill patients. In this review, we will describe four microvascular monitoring devices and give an overview of the microcirculatory changes observed during the course of sepsis. Laser Doppler fluxmetry is an easy to use noninvasive technique to measure tissue perfusion enabling monitoring of the effect of different catecholamines on the gastric perfusion during sepsis. Increased microvascular permeability and altered blood flow in septic patients can be quantified by venous congestion plethysmography. Alterations in sublingual microvascular blood flow are detected by intravital microscopy in septic patients and were identified as an outcome predictor. Furthermore, the role of gastrointestinal pCO2-tonometry for microcirculatory monitoring of the perfusion of splanchnic organs during sepsis is discussed. The true clinical value of these techniques has yet to be established and will depend on larger clinical trials showing an impact on diagnostics and patient management.
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Affiliation(s)
- A Bauer
- Klinik für Anaesthesiologie, Klinikum der Universität München-Grosshadern, Marchioninistrasse 15, 81377 München-Grosshadern
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Asfar P, Hauser B, Radermacher P, Matejovic M. Catecholamines and vasopressin during critical illness. Crit Care Clin 2006; 22:131-49, vii-viii. [PMID: 16399024 DOI: 10.1016/j.ccc.2005.08.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In critical care medicine, catecholamines are most widely used to reverse circulatory dysfunction and thus to restore tissue perfusion. However, catecholamines not only influence systemic and regional hemodynamics, but also exert a variety of significant metabolic, endocrine, and immunologic effects. Arginine vasopressin is a vasomodulatory hormone with potency to restore vascular tone in vasodilatory hypotension. Although the evidence supporting the use of low doses of vasopressin or its analogs in vasodilatory shock is increasing, lack of data regarding mortality and morbidity prevent their implementation in critical care protocols.
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Affiliation(s)
- Pierre Asfar
- Département de Réanimation Médicale, Centre Hospitalier Universitaire, 4 rue Larry, 49993 Angers Cedex 9, France
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