Tissue Oxygenation In Patients Research Articles

LAMA improves tissue oxygenation more than LABA in patients with COPD.

The effect of bronchodilators is mainly assessed with forced expiratory volume in 1 s (FEV1) in chronic obstructive pulmonary disease (COPD). Their impact on oxygenation and lung periphery is less known. Our objective was to compare the action of long-acting β2-agonists (LABA-olodaterol) and muscarinic antagonists (LAMA-tiotropium) on tissue oxygenation in COPD, considering their impact on proximal and peripheral ventilation as well as lung perfusion. FEV1, Helium slope (SHe) from a single-breath washout test (SHe decreases reflecting a peripheral ventilation improvement), frequency dependence of resistance (R5-R19), area under reactance (AX), lung capillary blood volume (Vc) from double diffusion (DLNO/DLCO), and transcutaneous oxygenation (TcO2) were measured before and 2 h post-LABA (day 1) and LAMA (day 3) in 30 patients with COPD (FEV1 54 ± 18% pred; GOLD A 31%/B 48%/E 21%) after 5-7 days of washout, respectively. We found that TcO2 increased more (P = 0.03) after LAMA (11 ± 12% from baseline, P < 001) compared with LABA (4 ± 11%, P = 0.06) despite a lower FEV1 increase (P = 0.03) and similar SHe (P = 0.98), AX (P = 0.63), and R5-R19 decreases (P = 0.37). TcO2 and SHe changes were negatively correlated (r = -0.47, P = 0.01) after LABA, not after LAMA (r = 0.10, P = 0.65). DLNO/DLCO decreased and Vc increased after LAMA (P = 0.04; P = 0.01, respectively) but not after LABA (P = 0.53; P = 0.24). In conclusion, LAMA significantly improved tissue oxygenation in patients with COPD, while only a trend was observed with LABA. The mechanisms involved may differ between both drugs: LABA increased peripheral ventilation, whereas LAMA increased lung capillary blood volume. Should oxygenation differences persist over time, LAMA could arguably become the first therapeutic choice in COPD.NEW & NOTEWORTHY Long-acting muscarinic antagonists (LAMAs) significantly improved tissue oxygenation in patients with COPD, while only a trend was observed with β2-agonists (LABAs). The mechanisms involved may differ between drugs: increased peripheral ventilation for LABA and likely lung capillary blood volume for LAMA. This could argue for LAMA as the first therapeutic choice in COPD.

The Effect of Ferritin Level on Respiratory Functions in Patients with β-Thalassemia Major

Introduction-Purpose β-thalassemia major (β-TM) is an autosomal recessive disorder caused by mutations in the β-globin gene of hemoglobin. The disease is characterized by splenomegaly due to ineffective erythropoiesis, iron accumulation signs in tissues as a result of increased iron absorption, bone expansion due to increased erythropoietic activity, and decreased tissue oxygenation. One of the effected organ can be the lungs due to excessive iron deposition in these patients. The current study aimed to investigate the effect of serum ferritin level, which is known as a marker of iron accumulation in tissues, on pulmonary function tests (PFT) in patients with β-TM. Methods and Materials Patients aged ≥6 years who were regularly followed in the pediatric hematology section of Mersin City Research and Training Hospital with a diagnosis of β-TM were included. All patients received regular blood transfusion and iron chelation therapy. Study participants underwent PFT prior to blood transfusion in the pediatric pulmonology section Results A total of 43 patients with β-TM were studied. Included patients were divided into two groups according to the mean annual ferritin level; low ferritin group if below 2000 ml/ng and high ferritin group if above 2000 ml/ng. The low ferritin group was consisted of 19 patients and the high ferritin group was consisted of 24 patients. The characteristics of these two groups are shown in Table 1. There were no statistical significance in age, gender, body mass index, age at diagnosis, mean annual hemoglobin, splenectomy, cardiac involvement and oxygen saturation among both groups, but the number of annual transfusion was significantly higher in the high ferritin group than lower ferritin group. When PFT parameters of both groups were compared, FVC (forced vital capacity) was statistically lower in the high ferritin group compared to the low ferritin group. Other parameters included FEV 1 (forced expiratory volume in 1 second), FEV 1/FVC ratio, PEF (peak expiratory flow) and FEF 25-75 (forced expiratory flow between 25% and 75% of vital capacity) were similar among groups. (Table 2) Discussion Patients with β-TM may accumulate iron in the interstitial area of the lungs which can lead fibrosis and impaired lung function over time. There are several studies investigated lung dysfunction and its etiology in these patients. Although the results of the studies are varied, the majority of them reported a restrictive pattern of respiratory dysfunction in thalassemia patients. Additionally, some studies showed the presence of mild or moderate obstruction in small airways and decrease in diffusion capacity with the increase of alveolar-capillary membrane thickness at advanced ages. In the present study, we found that patients with β-TM who had high ferritin level showed restrictive type lung function compared to those with low ferritin level. There were no difference among the groups in obstructive parameters (i.e. FEV 1, FEV 1/FVC, FEF 25-75) of PFT. In the literature, studies investigating PFT in patients with high ferritin levels had variable results, impaired or no change, in pulmonary status. In conclusion, loss of respiratory function and impaired tissue oxygenation in patients with β-TM may develop over time due to iron deposition in the interstitial area. PFT assessment of these patients is essential and recommended for the detection of early lung disease. Routine PFT follow in patients with β-TM of high ferritin values is highly important.

Altered tissue oxygenation in patients with post COVID-19 syndrome.

Post COVID-19 syndrome (PCS) is a complex condition with partly substantial impact on patients' social and professional life and overall life quality. Currently, the underlying cause(s) of PCS are unknown. Since PCS-specific symptoms could be associated with systemic alterations in tissue oxygen supply, we aimed to investigate changes in tissue oxygenation in patients with PCS. A case-control study including 30 PCS patients (66.6 % males, 48.6 ± 11.2 years, mean time after (first) acute infection: 324 days), 16 cardiologic patients (CVD) (65.5 % males, 56.7 ± 6.3 years) and 11 young healthy controls (55 % males, 28.5 ± 7.4 years) was conducted. Near infrared spectroscopy (NIRS) was used to assess changes in tissue oxygenation during an arterial occlusion protocol on the non-dominant forearm (brachioradialis, 760/850 nm, 5 Hz). The protocol included 10-min rest, a 2-min baseline measurement followed by a 3-min ischemic period (upper-arm cuff, 50 mmHg above resting systolic blood pressure) and a 3-min reoxygenation period. PCS patients were grouped by presence of arterial hypertension and elevated BMI to assess the impact of risk factors. No differences in mean tissue oxygenation in the pre-occlusion phase existed between groups (p ≥ 0.566). During ischemia, comparisons of linear regressions slopes revealed slower oxygen desaturation for PCS patients (-0.064 %/s) compared to CVD patients (-0.08 %/s) and healthy subjects (-0.145 %/s) (p < 0.001). After cuff release, slowest speed for reoxygenation was detected in PCS patients at 0.84 %/s compared to CVD patients (1.04 %/s) and healthy controls (CG: 2.07 %/s) (p < 0.001). The differences between PCS patients and CVD patients during ischemia remained significant also after correction for risk factors. Analyses of complications during acute infection, persistence of PCS symptoms (time after acute infection), or PCS severity (number of lead symptoms) as confounding factors did not reveal a significant effect. This study provides evidence that the rate of tissue oxygen consumption is persistently altered in PCS and that PCS patients show an even slower decline in tissue oxygenation during occlusion than CVD patients. Our observations may at least partly explain PCS-specific symptoms such as physical impairment and fatigue.

Control of tissue oxygenation by S-nitrosohemoglobin in human subjects

S-Nitrosohemoglobin (SNO-Hb) is unique among vasodilators in coupling blood flow to tissue oxygen requirements, thus fulfilling an essential function of the microcirculation. However, this essential physiology has not been tested clinically. Reactive hyperemia following limb ischemia/occlusion is a standard clinical test of microcirculatory function, which has been ascribed to endothelial nitric oxide (NO). However, endothelial NO does not control blood flow governing tissue oxygenation, presenting a major quandary. Here we show in mice and humans that reactive hyperemic responses (i.e., reoxygenation rates following brief ischemia/occlusion) are in fact dependent on SNO-Hb. First, mice deficient in SNO-Hb (i.e., carrying C93A mutant Hb refractory to S-nitrosylation) showed blunted muscle reoxygenation rates and persistent limb ischemia during reactive hyperemia testing. Second, in a diverse group of humans-including healthy subjects and patients with various microcirculatory disorders-strong correlations were found between limb reoxygenation rates following occlusion and both arterial SNO-Hb levels (n = 25; P= 0.042) and SNO-Hb/total HbNO ratios (n = 25; P= 0.009). Secondary analyses showed that patients with peripheral artery disease had significantly reduced SNO-Hb levels and blunted limb reoxygenation rates compared with healthy controls (n = 8 to 11/group; P< 0.05). Low SNO-Hb levels were also observed in sickle cell disease, where occlusive hyperemic testing was deemed contraindicated. Altogether, our findings provide both genetic and clinical support for the role of red blood cells in a standard test of microvascular function. Our results also suggest that SNO-Hb is a biomarker and mediator of blood flow governing tissue oxygenation. Thus, increases in SNO-Hb may improve tissue oxygenation in patients with microcirculatory disorders.

THE EFFECTS OF MINIMAL, LOW AND HIGH FLOW ANESTHESIA ON BODY TEMPERATURE AND TISSUE OXYGENATION IN NASAL SURGERIES

OBJECTIVE: Intraoperative high fresh gas flow may cause Inadvertent perioperative hypothermia (IPH). For this reason, low and minimal flow anesthesia methods that improve the anesthesia climate are applied. We aimed to investigate the effects of minimal, low and high flow anesthesia on body temperature and tissue oxygenation in patients undergoing elective nasal surgery.MATERIAL AND METHODS: Prospective randomized controlled study included 92 patients aged 18-60 years, ASA1-2 operation time 1-4 hours, scheduled for elective nasal surgery under hypotensive anesthesia. The patients were divided into Group 1 (0.5Lmin-1), Group 2 (1Lmin-1) and Group 3 (2 Lmin-1). Demographic and operative data of the patients, preoperative waiting room temperature, intraoperative operating room temperature, intraoperative body temperature, anesthesia breathing circuit humidity and temperature, tissue oxygen saturation, 0th, 15th, 30th, 60th, 90th, 120th, 150thmin and postoperative shivering, Aldrete score, room temperature and body temperatures in the recovery unit were recorded.RESULTS: Perioperative hypothermia developed in all patients (p=0.001). Tympanic temperatures were similar in all three groups (p&amp;gt;0.05). In the subgroup comparison, it was found that the tissue oxygen saturation (StO2) 60 th min value of Group1 was higher than Group 2 (p=0.046). It was found statistically significant that the StO2 90 th min value of Group1 was higher than that of Group 2 and 3 (p=0.013, p=0.013). It was statistically significant that the StO2 120th min value of Group1 was higher than Group 3 (p=0.008).In Group1, postoperativeAldrete score was found to be significantly higher than the other two groups(p=0.002, p=0.002). A correlation was found between operating room temperature, postoperative recovery room temperature, and body temperature(r=.446, p&amp;lt;0.05;r=.531, p&amp;lt;0.01).CONCLUSIONS: Inadvertent perioperative hypothermia developed in all patients who underwent elective nasal surgery with hypotensive anesthesia in minimal, low and high flow anesthesia applications. It was observed that body temperatures, humidity and the temperature of the anesthesia period were similar in all groups. Tissue oxygen saturation was higher in the minimal flow anesthesia group and Aldrete score was higher in the postoperative recovery unit. Minimal flow anesthesia applications can be a good alternative to prevent IPH. However, we think that more studies are needed for the effects of low-flow anesthesia techniques at the tissue level.

Significance of tissue oxygenation in patients connected to a mechanical ventilator

Significance of tissue oxygenation in patients connected to a mechanical ventilator

Metal-Phenolic Networks as Broad-Spectrum Antioxidant Coatings for Hemoglobin Nanoparticles Working as Oxygen Carriers

Timely administration of donor red blood cells (RBCs) is a crucial and life-saving procedure to restore tissue oxygenation in patients suffering from acute blood loss. However, important drawbacks of using allogenic RBCs are their limited availability and portability, specific storage requirements, short shelf life, or the need for blood type matching. These limitations result in serious logistical challenges that make the transfusion of donor RBCs difficult in extreme life-threatening situations prior to hospital admission. Thus, the engineering of hemoglobin (Hb) nanoparticles (Hb-NPs), which are free from the aforementioned limitations, has emerged as a promising strategy to create RBC substitutes to be used when donor blood is not available. Despite the tremendous progress achieved in recent years, many challenges still need to be overcome. For example, it is still difficult to create Hb-NPs with a high Hb content while also preventing the autoxidation of Hb into nonfunctional methemoglobin (metHb). Herein, the fabrication of small, solid Hb-NPs with an antioxidant coating is reported. By desolvation precipitation, Hb-NPs with an average hydrodynamic diameter of ∼250 nm and a polydispersity index of ∼0.2 are fabricated. A metal-phenolic network (MPN) layer consisting of a phenolic ligand (i.e., tannic acid) cross-linked through iron(III) ions is deposited onto the Hb-NPs surface to render antioxidant protection. The resulting MPN-coated Hb-NPs (MPN@Hb-NPs) maintain the ability of the encapsulated Hb to reversibly bind and release oxygen. The antioxidant properties are demonstrated, showing that MPN@Hb-NPs can effectively scavenge multiple reactive oxygen and nitrogen species, both in solution and in the presence of human RBCs and two relevant cell lines, namely, macrophages and endothelial cells. Importantly, these outstanding antioxidant properties resulting from the MPN translate into decreased metHb conversion. Finally, the newly reported MPN@Hb-NPs are also biocompatible, as shown by hemolysis rate and cell viability studies and can be used to protect the cells from oxidative damage. All in all, we have identified a novel strategy to minimize heme-mediated oxidative reactions that could potentially bring this new generation of Hb-based oxygen carriers a step closer to the clinic.

Increased tissue water in patients with severe sepsis affects tissue oxygenation measured by near-infrared spectroscopy: a prospective, observational case-control study.

BackgroundTissue oedema affects tissue perfusion and interferes with the monitoring of tissue oxygenation in patients with severe sepsis. However, the underlying mechanisms remain unclear. We used a wireless near-infrared spectroscopy (NIRS) device that transmits tri-wavelength light to quantify tissue haemoglobin (Hb) and water (H2O) content. We estimated tissue H2O in severe sepsis patients and healthy controls, compared their difference, and investigated the correlation of tissue H2O with systemic haemodynamics and its impact on tissue oxygenation.MethodsSeventy-seven adult patients with new-onset severe sepsis admitted to the intensive care unit within 72 h and 30 healthy volunteers (controls) were enrolled. The NIRS device was placed on the participant’s leg to estimate the relative tissue concentrations of oxy-Hb ([HbO2]), deoxy-Hb ([HbR]), total Hb ([HbT]), and H2O ([H2O]) at rest for three consecutive days. Two-sample t-test or Mann-Whitney U test, chi-square test, and generalised estimating equations (GEEs) were used for comparisons.ResultsIn severe sepsis patients, the [H2O] in the anterior tibia was higher [mean (standard deviation, 95% confidence interval), 10.57 (3.37, 9.81–11.34) vs. 7.40 (1.89, 6.70–8.11)] and the [HbO2], [HbT], and tissue Hb oxygen saturation (StO2) were lower [0.20 (0.01, 0.20–0.20) vs. 0.22 (0.01, 0.22–0.23), 0.42 (0.02, 0.42–0.43) vs. 0.44 (0.02, 0.44–0.45), and 47.25% (1.97%, 46.80–47.70%) vs. 49.88% (1.26%, 49.41–50.35%), respectively] than in healthy controls in first-day measurements. GEE analysis revealed significant differences in [H2O], [HbO2], [HbT], and StO2 between groups over three consecutive days (all P≤0.001). In addition, [HbO2] and StO2 levels gradually decreased over time in the patient group. A negative correlation was observed between [H2O] and [HbO2] and StO2, which became more obvious over time (day 1: r=−0.51 and r=−0.42, respectively; both P<0.01; day 3: r=−0.67 and r=−0.63, respectively, both P<0.01). Systolic arterial pressure was positively related to [H2O] (r=0.51, P<0.05, on day 1) but was not associated with tissue oxygenation parameters.ConclusionsNIRS can be used to quantify tissue H2O. Severe sepsis patients have increased tissue H2O, which responds to changes in arterial blood pressure and affects tissue oxygenation.

Abstract 557: Stretching With Ankle Dorsiflexion Splint Improves Measures Of Microvascular Reactivity And Oxygen Extraction In Patients With Peripheral Artery Disease

Peripheral Artery Disease (PAD) is a vascular disease that affects over 8 million Americans. PAD patients commonly have difficulty walking due to pain in the legs during physical exertion. Supervised walking therapy has been recommended to improve walking performance and attenuate disease progression; however, this therapy remains underutilized in PAD patients. Recently, there has been evidence to suggest that stretching accomplished via an ankle dorsiflexion splint may improve vascular health and walking performance in PAD; however, it is currently unknown how this protocol affects tissue oxygenation (StO 2 ). The purpose of this study was to determine the impact of 4 wks of ankle dorsiflexion stretching on measures of tissue oxygenation in patients with PAD. Thirteen PAD patients (67.7 ± 7.9 years) were randomized to a stretch (n = 9) or a non-stretch control (n = 4) group. Patients in the stretch were instructed to wear the splint for 30 min/day, 5 days/wk for 4 wks. A 5-min vascular occlusion test was administered before and after the intervention. Measures of StO 2 recovery were calculated following the vascular occlusion test and while completing a 6-minute walk test (6MWT). All measures of StO 2 were derived via Near-Infrared Spectroscopy. Repeated measures ANOVA was used to analyze data. There was a significant improvement in StO 2 recovery in the stretch group compared to the control (Stretch: 0.35 ± 0.25 %/sec vs 0.53 ± 0.29 %/sec; Control: 0.57 ± 0.43 %/sec vs 0.32 ± 0.19 %/sec; p = 0.002). During the 6MWT, patients completing the stretching protocol significantly improved oxygen extraction in the first minute of the test (-0.63 ± 0.05 StO 2 vs -0.73 ± 0.09 StO 2 ); however, this improvement was not significantly different compared to changes in the control group. These results indicate an improvement in microvascular reactivity and oxygen extraction following 4 wks of splint-based stretching. This stretching intervention holds potential therapeutic value for PAD patients and warrants further investigation.

The Effects of Endotracheal Suctioning on Hemodynamic Parameters and Tissue Oxygenation in Pediatric Intensive Care Unit.

Airway secretions may increase in intubated patients due to the impaired mucociliary clearance, impaired cough reflex, abnormal glottic function, insufficient moisturizing, and respiratory tract infections. As with any intervention, patients should be cautiously monitored for possible complications during the endotracheal suctioning. Procedure-related changes in the cerebral and somatic tissue oxygenation, hemodynamics, and oxygen saturation can be observed in these patients. It is important to ensure maintenance of tissue oxygenation during these and other interventions performed in critically ill children. The aim of this study was to investigate the effects of the endotracheal suctioning on tissue oxygenation in patients undergoing mechanical ventilation in the pediatric intensive care unit. Cerebral and somatic near-infrared spectroscopy (NIRS) monitoring were performed noninvasively using standardized NIRS equipment as a means of monitoring regional tissue oxygenation. Vital signs, level of sedation, pain scores, and somatic and cerebral tissue oxygenation values of mechanically ventilated patients were recorded prospectively 5 minutes before, during, and after endotracheal suctioning. Cerebral NIRS measurements did not exhibit any statistically significant changes during endotracheal suctioning. Somatic NIRS levels changed significantly before, during, and after endotracheal suctioning and remained low throughout the procedure. Endotracheal suctioning is an invasive intervention that facilitates clearance of tracheal secretions and maintenance of the oxygenation and ventilation. The maintenance of the tissue oxygenation should be documented during these and other interventions performed on critically ill children. Somatic NIRS is a useful tool for monitoring tissue oxygenation during such procedures.

Individualized Brain Tissue Oxygen-Monitoring Probe Placement Helps to Guide Therapy and Optimizes Outcome in Neurocritical Care

Background/ObjectiveIn order to monitor tissue oxygenation in patients with acute neurological disorders, probes for measurement of brain tissue oxygen tension (ptO2) are often placed non-specifically in a right frontal lobe location. To improve the value of ptO2 monitoring, placement of the probe into a specific area of interest is desirable. We present a technique using CT-guidance to place the ptO2 probe in a particular area of interest based on the individual patient’s pathology.MethodsIn this retrospective cohort study, we analyzed imaging and clinical data from all patients who underwent CT-guided ptO2 probe placement at our institution between October 2017 and April 2019. Primary endpoint was successful placement of the probe in a particular area of interest rated by two independent reviewers. Secondary outcomes were complications from probe insertion, clinical consequences from ptO2 measurements, clinical outcome according to the modified Rankin Scale (mRS) as well as development of ischemia on follow-up imaging. A historical control group was selected from patients who underwent conventional ptO2 probe placement between January 2010 and October 2017.ResultsEleven patients had 16 CT-guided probes inserted. In 15 (93.75%) probes, both raters agreed on the correct placement in the area of interest. Each probe triggered on average 0.48 diagnostic or therapeutic adjustments per day. Only one infarction within the vascular territory of a probe was found on follow-up imaging. Eight out of eleven patients (72.73%) reached a good outcome (mRS ≤ 3). In comparison, conventionally placed probes triggered less diagnostic and therapeutic adjustment per day (p = 0.007). Outcome was worse in the control group (p = 0.024).ConclusionCT-guided probe insertion is a reliable and easy technique to place a ptO2 probe in a particular area of interest in patients with potentially reduced cerebral oxygen supply. By adjusting treatment aggressively according to this individualized monitoring data, clinical outcome may improve.

A prospective trial of intraoperative tissue oxygenation measurement and its association with anastomotic leak rate after Ivor Lewis esophagectomy.

BackgroundAnastomotic leak following Ivor Lewis esophagectomy is associated with increased morbidity/mortality and decreased survival. Tissue oxygenation at the anastomotic site may influence anastomotic leak. Methods for establishing tissue oxygenation at the anastomotic site are lacking.MethodsOver a 2-year study period, 185 Ivor Lewis esophagectomies were performed. Study participants underwent measurement of gastric conduit tissue oxygenation at the planned anastomotic site using the wireless pulse oximetry device. Associations between anastomotic leaks or strictures and tissue oxygenation levels were analyzed using Wilcoxon rank sum test or Fisher’s exact test.ResultsAmong study participants (n=114), median gastric conduit tissue oxygenation level was 92% (range, 62–100%). There were 8 (7.0%) anastomotic leaks and 3 (2.6%) strictures. Analysis of tissue oxygenation as a continuous variable showed no difference in median tissue oxygenation in patients with and without leaks (98% and 92%; P=0.2) and stricture formation (89% and 92%; P=0.6). Analysis of tissue oxygenation as a dichotomous variable found no difference in anastomotic leak rates [7.5% (n=93) in >80% vs. 0% (n=20) in ≤80%; P=0.3]. There were no significant differences in leak rates in concurrent study nonparticipants.ConclusionsNo significant association was observed between intraoperative tissue oxygenation at the anastomotic site and subsequent anastomotic leak or stricture formation among patients undergoing Ivor Lewis esophagectomy.

Pharmacologically versus endogenously induced changes in tissue oxygenation, measured by near infrared spectroscopy (NIRS)

Introduction Near-infrared spectroscopy (NIRS) enables continuous estimation of regional tissue oxygen saturation (rStO2). Ensuring adequate tissue oxygenation in patients undergoing general anaesthesia is of paramount importance to prevent post-procedural end-organ dysfunction. During endotracheal intubation, laryngoscopy elicits an endogenous stress response, resulting in an increased mean arterial pressure (MAP). Intraoperatively, vasopressors are routinely used to counter anaesthesia-related hypotension. Since rStO2 is MAP-dependent, we aimed to study whether changes in rStO2 differ depending on the origin of increased MAP. Methods After ethical approval and written informed consent, we randomly assigned 28 patients undergoing arterial dilation of the lower limb. Phenylephrine or ephedrine were administered according to a predefined scheme, when MAP dipped below 20% from baseline. Cerebral (rScO2) and paravertebral (rSpvO2, measured at T3, T9 and lumbar) rStO2 were measured. Differences in changes in rScO2 and rSpvO2 following MAP increase obtained by vasopressor administration or laryngoscopy, were compared. After rigorous selection of fixed effects to minimize risk of multicollinearity, a linear mixed model was used to determine predicted effects of each intervention on rStO2, with intervention, rStO2-location and their two way interaction as fixed effects. Results We observed a significant increase in rScO2 (+6.27% [CI 5.19, 7.36]) following laryngoscopy, compared to ephedrine (-0.15% [CI -0.86, +0.56]) and phenylephrine (-1.57% [CI -2.27, -0.87]). rSpvO2 showed a decrease following laryngoscopy of -2.91% [CI -3.78, -2.03], whereas no changes were noted after administration of ephedrine (-0.65% [CI -1.36, +0.06]) or phenylephrine +0.35% ([CI -0.36, +1.05]). Discussion MAP increase following tracheal intubation resulted in a significantly higher rise in rScO2 and a significant lower rSpvO2 compared to changes in rStO2 following pharmacologically induced MAP increases.

Reply to Drs. Henni and Abraham: Muscle oxygen content at exercise in patients with claudication

to the editor: We are grateful for the opportunity to further discuss the topic of tissue oxygenation in patients with peripheral artery disease (PAD) ([4][1]). Both near-infrared spectroscopy (NIRS) and transcutaneous oxygen pressure (TcPO2) are useful techniques to determine blood flow to lower

In This Issue

HomeCirculation ResearchVol. 120, No. 9In This Issue Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIn This Issue Ruth Williams Ruth WilliamsRuth Williams Search for more papers by this author Originally published28 Apr 2017https://doi.org/10.1161/RES.0000000000000150Circulation Research. 2017;120:1367Flow-Induced Lymphatic Growth (p 1426)Download figureDownload PowerPointChoi et al discover how tissue fluid flow prompts lymphatic vessel development.A fully functional lymphatic vasculature is essential for draining interstitial fluid and preventing tissue edema. Interestingly, research suggests that in the growing embryo the very presence and flow of fluid within tissues prompts lymph development. To understand how tissue fluids generate their own drainage system, Choi and colleagues focused on lymphatic endothelial cells (LECs), which give rise to the vessels. They showed that a steady laminar flow of culture medium over LECs, but not blood vessel ECs, induced these cells to proliferate. They also showed that proliferation-promoting transcription factors were upregulated in flow-treated LECs and that blocking the actions of these factors reduced flow-induced proliferation. Laminar flow is known to induce calcium influx in LECs, and the team went on to show that a plasma membrane calcium channel, called CRAC, was an integral link between laminar flow and proliferation, a link supported by the observation that knocking down a key component of the channel (a subunit called ORAI1) prevented the flow-activated proliferation of LECs. Moreover, in mice lacking functional ORAI1, lymph vessel density was reduced. Together, these results provide new insights into the development of the lymphatic system and may shed light on how, in certain lymphatic disorders, this process goes awry.Transcellular Solute Transport in Lymphatics (p 1440)Download figureDownload PowerPointSolutes travel to lymph vessels both through and between lymphatic endothelial cells, report Triacca et al.The interstitial fluid in the body is continuously drained via lymphatic vessels, accumulating first in the nodes before eventually returning to the blood. This draining process has been thought to be largely passive—the result of hydrostatic pressure differences between the tissues and lymph vessels. Indeed, fluid flow into a vessel’s lumen was thought to occur primarily between the lymphatic endothelial cells (LECs), which form the vessel lining. However, there is little direct evidence to support this view, and recent evidence suggests that solute-filled vesicles could also transit across the LEC cytoplasm. To find out, Triacca and colleagues injected fluorescent albumin into the dermis of mouse ears and observed the protein’s passage to the lymph. They found that the albumin entered LECs, and in vitro studies confirmed that the protein was transported via vesicles. The team went on to show that solute uptake via this transcellular pathway was boosted by both increased fluid flow and the presence of inflammatory molecules. These results indicate that, in addition to passive paracellular transport, solute passage to the lymph can be actively controlled by LECs—a finding that could impact our understanding of the maintenance of tissue homeostasis, as well as the resolution of inflammation.4D Analysis of Regenerative Angiogenesis (p 1453)Download figureDownload PowerPointArpino et al’s close examination of regenerating microvessels reveals flaws.After an ischemic injury, the affected tissue undergoes rapid vasculogenesis. But it is unclear whether the newly regenerated vessels fully resemble the anatomy and function of normal vessels. To address this question, Arpino and colleagues decided to take a closer, more high-resolution look. Using a combination of intravital and confocal microscopy, they examined the regrowth of microvessels after hind limb ischemia in mice. They found that, although the vessels regenerated rapidly and robustly in the animals’ legs, the branching architecture of the vessels was aberrant, and the transit of red blood cells through the capillaries was slow, and disorderly, and did not respond adequately to local hypoxia. The researchers also found that smooth muscle cells surrounding the vessels did not form a continuous uniform layer as expected. These abnormalities persisted for several months after injury. The authors conclude that future therapeutic revascularization strategies must achieve more than just vessel regrowth if they are to restore tissue oxygenation in patients with ischemia. Previous Back to top Next FiguresReferencesRelatedDetails April 28, 2017Vol 120, Issue 9 Advertisement Article InformationMetrics © 2017 American Heart Association, Inc.https://doi.org/10.1161/RES.0000000000000150 Originally publishedApril 28, 2017 PDF download Advertisement

Quantitative analysis of mucosal oxygenation using ex vivo imaging of healthy and inflamed mammalian colon tissue.

Colonic inflammation is associated with decreased tissue oxygenation, significantly affecting gut homeostasis. However, the crosstalk between O2 consumption and supply in the inflamed tissue are not fully understood. Using a murine model of colitis, we analysed O2 in freshly prepared samples of healthy and inflamed colon tissue. We developed protocols for efficient ex vivo staining of mouse distal colon mucosa with a cell-penetrating O2 sensitive probe Pt-Glc and high-resolution imaging of O2 concentration in live tissue by confocal phosphorescence lifetime-imaging microscopy (PLIM). Microscopy analysis revealed that Pt-Glc stained mostly the top 50-60μm layer of the mucosa, with high phosphorescence intensity in epithelial cells. Measured O2 values in normal mouse tissue ranged between 5 and 35μM (4-28Torr), tending to decrease in the deeper tissue areas. Four-day treatment with dextran sulphate sodium (DSS) triggered colon inflammation, as evidenced by an increase in local IL6 and mKC mRNA levels, but did not affect the gross architecture of colonic epithelium. We further observed an increase in oxygenation, partial activation of hypoxia inducible factor (HIF) 1 signalling, and negative trends in pyruvate dehydrogenase activity and O2 consumption rate in the colitis mucosa, suggesting a decrease in mitochondrial respiration, which is known to be regulated via HIF-1 signalling and pyruvate oxidation rate. These results along with efficient staining with Pt-Glc of rat and human colonic mucosa reveal high potential of PLIM platform as a powerful tool for the high-resolution analysis of the intestinal tissue oxygenation in patients with inflammatory bowel disease and other pathologies, affecting tissue respiration.

Brain Tissue Oxygenation in Patients with Septic Shock: a Feasibility Study.

Delirium is common in critically ill patients and its presence is associated with increased mortality and increased likelihood of poor cognitive function among survivors. However, the cause of delirium is unknown. The purpose of this study was to demonstrate the feasibility of using near-infrared spectroscopy (NIRS) to assess brain tissue oxygenation in patients with septic shock, who are at high risk of developing delirium. This prospective observational study was conducted in a 33-bed general medical surgical intensive care unit (ICU). Patients with severe sepsis or septic shock were eligible for recruitment. The FORESIGHT NIRS monitor was used to assess brain tissue oxygenation in the frontal lobes for the first 72 hours of ICU admission. Physiological data was also recorded. We used the Confusion Assessment Method-ICU to screen for delirium. From March 1st 2014-September 30th 2014, 10 patients with septic shock were recruited. The NIRS monitor captured 81% of the available data. No adverse events were recorded. Brain tissue oxygenation demonstrated significant intra- and inter-individual variability in the way it correlated with physiological parameters, such as mean arterial pressure, heart rate, and peripheral oxygen saturation. Mean brain tissue oxygen levels were significantly lower in patients who were delirious for the majority of their ICU stay. It is feasible to record brain tissue oxygenation with NIRS in patients with septic shock. This study provides the infrastructure necessary for a larger prospective observational study to further examine the relationship between brain tissue oxygenation, physiological parameters, and acute neurological dysfunction.

Near-infrared spectroscopy to assess tissue oxygenation in patients with polytrauma: relationship with outcome

We evaluated tissue oxygenation by means of near-infrared spectroscopy (NIRS) and explored its relationship with outcome in polytrauma patients.

Effect of ischemic and pharmacological preconditioning of lower limb muscle tissue on tissue oxygenation measured by near-infrared spectroscopy--a pilot study.

BackgroundIschemic or volatile anesthetic preconditioning is defined as tissue protection from impending ischemic cell damage by repetitive short periods of tissue exposure to ischemia or volatile anesthetics. Objective of this study was to elucidate, if ischemic preconditioning and pharmacological preconditioning with sevoflurane have effects on muscle tissue oxygen saturation in patients undergoing surgical revascularization of the lower limb.MethodsIn this prospective randomized pilot study ischemic and pharmacological (sevoflurane) preconditioning was performed in 40 patients with lower limb arterial occlusive disease undergoing surgical revascularization. Sevoflurane preconditioning was performed in one group (N = 20) by repetitive application of sevoflurane for six minutes interspersed by six minutes of washout. Thereafter, ischemic preconditioning was performed in all patients (N = 40) by repetitive clamping of the femoral artery for six minutes interspersed by six minutes of reperfusion. The effect of both procedures on leg muscle tissue oxygen saturation (rSO2) was measured by near-infrared spectroscopy during both procedures and during surgery and reperfusion (INVOS® 5100C Oxymeter with Small Adult SomaSensor® SAFB-SM, Somanetics, Troy, Michigan, USA).ResultsRepetitive clamping and reperfusion of the femoral artery resulted in significant cyclic decrease and increase of muscle rSO2 (p < 0.0001). Pharmacological preconditioning with sevoflurane resulted in a faster and higher increase of rSO2 during postoperative reperfusion (Maximal 111% baseline ± 20 versus 103% baseline ± 14, p = 0.008) consistent with an additional effect of pharmacological preconditioning on leg perfusion.ConclusionsIschemic preconditioning of lower limb muscle tissue and pharmacological preconditioning with sevoflurane have an effect on tissue oxygenation in patients with lower limb occlusive arterial disease.Trial registrationThe trial has been registrated at http://www.ClinicalTrial.gov, Trial Number: NCT02038062 at 14 January 2014.

Gene therapy: A novel way to treat respiratory failure?

Respiratory failure leads to tissue hypoxia and subsequent organ damage. The crocodile hemoglobin affinity for oxygen is significantly reduced in the presence of CO2, allowing crocodiles to stay under water for more than 1h. The crocodile bicarbonate effect can possibly be transplanted into the human hemoglobin by replacing only five and seven amino acid residues in the β-globin and α-globin chains, respectively. The resulting hybrid formed by these modified chains has been named Scuba hemoglobin. The in vitro production of Scuba hemoglobin by human hematopoietic stem cells and their reintroduction into the blood could be an interesting tool to improve tissue oxygenation in patients suffering from respiratory failure.