Acute Effects of Smoking on Skeletal Muscle Microcirculation Monitored by Near-Infrared Spectroscopy

Acute Effects of Nicotine on Physiological Responses and Sport Performance in Healthy Baseball Players

There is interest in whether nicotine could enhance attention in sporting performance, but evidence on the acute effect of nicotine on physical response and sports performance in baseball players remains scant. This was an observational study to examine whether nicotine gum chewed before exercise could provide acute effects on physiological responses and sport performance. Accordingly, heart rate variability (HRV), saliva cotinine concentration and α-amylase activity, cognitive function, muscle strength, and baseball-hitting performance were measured. Thirteen healthy male non-smoker baseball players were recruited. Conducting two sequences with 7-day intervals, they chewed nicotine gum (nicotine group) or flavor-matched placebo gum (placebo group) for 30 min. HRV and saliva analyses were conducted before gum consumption (S1), after gum consumption (S2), and after test completion (S3). Cognitive, muscle strength, and baseball-hitting performance tests were performed after nicotine or placebo gum chewing. The outcomes of all assessed variables were compared within and between the groups. Significant changes in HRV, α-amylase, testosterone, and cortisol were observed in the nicotine group at S2 and S3 (p < 0.05). Compared with the placebo group, the nicotine group exhibited enhanced motor reaction times, grooved pegboard test (GPT) results on cognitive function, and baseball-hitting performance, and small effect sizes were noted (d = 0.47, 0.46 and 0.41, respectively). Nicotine could induce changes in endocrine and sympathetic nerve activity and enhance cognitive function and baseball-hitting performance. However, no increase in muscle strength was observed after nicotine intake.

Young healthy adults with a family history of hypertension have increased microvascular reactivity but decreased macrovascular function

OBJECTIVE

To determine whether, like hypertensives, normotensive adults with a family history of hypertension (+FHH) display lower microvascular reactivity and conduit artery function than normotensive adults without a family history of hypertension (-FHH).

METHODS

A forearm vascular occlusion test was performed on healthy normotensive adults while resting in the supine position. A near-infrared spectroscopy sensor placed on the forearm measured skeletal muscle oxygen saturation kinetics to determine microvascular reactivity. Simultaneously, an ultrasound probe placed on the brachial artery above the occlusion cuff was used to assess flow-mediated dilation; a test of macrovascular function.

RESULTS

Twenty-two participants were included in this investigation (-FHH n = 13, +FHH n = 9). Following cuff release, the resaturation slope (1st 10 s median ± SD, -FHH 2.76 ± 2.10, +FHH 5.59 ± 2.47%/s; p = .036) was greater in +FHH when accounting for the magnitude and rate of the decrease in skeletal muscle oxygen saturation during occlusion. Conversely, flow-mediated dilation (median ± SD, -FHH 5.96 ± 5.22, +FHH 4.10 ± 3.17%∆; p = .031) was lower in +FHH when accounting for baseline artery diameter and shear rate.

CONCLUSIONS

Young +FHH adults have altered microvascular and macrovascular reactivity compared with young -FHH adults.

The effect of cigarette smoking history on autonomic and cerebral oxygenation responses to an acute exercise bout in smokers

The extent of smoking history is causally linked to adverse cerebro- and cardiovascular health outcomes, while conversely, exercise decreases this risk and associated mortality. However, the acute cerebro- and cardiovascular responses to exercise in smokers are unknown, and may provide insight to understand chronic adaptation. This study examined the acute heart rate (HR) variability (R-R intervals) and cerebral oxygenation responses to exercise in smokers compared to nonsmokers. Fifty-four males classified as smokers (n = 27) or nonsmokers (n = 27) were allocated into either younger (YSM, YNS) or middle-aged groups (MSM, MNS). Participants completed 40 min of stationary cycle ergometry at 50% of VO2peak. Cerebral oxygenation (near-infrared spectroscopy) and autonomic function (HR variability) were collected before, during, and after exercise at 0, 30 min, 1, and 4 hr postexercise. The nonsmoker cohort (MNS and YNS) demonstrated higher values for the standard deviation (SD) of the R-R interval (SDNN) and the root mean squared of the SD at 1 and 4 hr postexercise versus smokers (p < .05). The low frequency (LF) band in YSM was lower than in YNS at 1 hr (p < .05). However, LF and high frequency were higher for MNS compared to MSM at 1 hr (p < .05). Oxygenated hemoglobin during and following exercise were elevated in NS with values for MSM lower than YSM (p < .05). The findings show smoking history can affect cerebral oxygenation during and following an acute exercise bout. Further, following exercise, smokers may exhibit a delay or inhibition in parasympathetic activity.

Reactive hyperemia: a review of methods, mechanisms, and considerations

Reactive hyperemia is a well-established technique for noninvasive assessment of peripheral microvascular function and a predictor of all-cause and cardiovascular morbidity and mortality. In its simplest form, reactive hyperemia represents the magnitude of limb reperfusion following a brief period of ischemia induced by arterial occlusion. Over the past two decades, investigators have employed a variety of methods, including brachial artery velocity by Doppler ultrasound, tissue reperfusion by near-infrared spectroscopy, limb distension by venous occlusion plethysmography, and peripheral artery tonometry, to measure reactive hyperemia. Regardless of the technique used to measure reactive hyperemia, blunted reactive hyperemia is believed to reflect impaired microvascular function. With the advent of several technological advancements, together with an increased interest in the microcirculation, reactive hyperemia is becoming more common as a research tool and is widely used across multiple disciplines. With this in mind, we sought to review the various methodologies commonly used to assess reactive hyperemia and current mechanistic pathways believed to contribute to reactive hyperemia and reflect on several methodological considerations.

Effect of Cigarette Smoking on Patient-Reported Outcomes in Hip Arthroscopic Surgery: A Matched-Pair Controlled Study With a Minimum 2-Year Follow-up

Background

The rate of hip arthroscopic surgery has recently increased; however, there is limited literature examining patient-reported outcomes (PROs) in cigarette smokers.

Purpose/Hypothesis

The purpose of this study was to evaluate whether smoking status for patients undergoing hip arthroscopic surgery affects clinical findings and PRO scores. We hypothesized that patients who smoke and undergo primary hip arthroscopic surgery will have similar clinical examination findings and preoperative and postoperative PRO scores compared with nonsmoking patients.

Study Design

Cohort study; Level of evidence, 3.

Methods

Data were collected on all patients who underwent primary hip arthroscopic surgery from February 2008 to July 2015. A retrospective analysis of the data was then conducted to identify patients who reported cigarette use at the time of the index procedure. Patients were matched 1:2 (smoking:nonsmoking) based on sex, age within 5 years, labral treatment (repair vs reconstruction vs debridement), workers' compensation status, and body mass index within 5 kg/m². All patients were assessed preoperatively and postoperatively using 4 PRO measures: the modified Harris Hip Score (mHHS), Non-Arthritic Hip Score (NAHS), Hip Outcome Score-Sport-Specific Subscale (HOS-SSS), and International Hip Outcome Tool-12 (iHOT-12). Pain was estimated using a visual analog scale. Satisfaction was measured on a scale from 0 to 10. Significance was set at P < .05.

Results

A total of 75 hips were included in the smoking group, and 150 hips were included in the control group. Preoperatively, the smoking group had significantly lower PRO scores compared with the control group for the mHHS, NAHS, and HOS-SSS. Both groups demonstrated significant improvement from preoperative levels. A minimum 2-year follow-up was achieved, with a mean of 42.5 months for the smoking group and 47.6 months for the control group (P = .07). At the latest follow-up, the smoking group reported inferior results for all outcome measures compared with controls. The improvement in PRO scores and rates of treatment failure, revision arthroscopic surgery, and complications was not statistically different between the groups.

Conclusion

Patients who smoke had lower PRO scores preoperatively and at the latest follow-up compared with nonsmokers. Both groups demonstrated significant improvement in all PRO scores. These results show that while hip arthroscopic surgery may still yield clinical benefit in smokers, these patients may ultimately achieve an inferior functional status. To optimize results, physicians should advise patients to cease smoking before undergoing hip arthroscopic surgery.

Risk Factors Associated With Musculoskeletal Injury: A Prospective Study of British Infantry Recruits

Background:

Musculoskeletal Injury (MSKI), a common problem in both military and physically active civilian populations, has been suggested to result from both extrinsic and intrinsic factors.

Objective:

To investigate prospectively whether gait biomechanics, aerobic fitness levels and smoking status as well as entry military selection test variables can be used to predict MSKI development during recruit training.

Methods:

British infantry male recruits (n = 562) were selected for the study. Plantar pressure variables, smoking habit, aerobic fitness as measured by a 1.5 mile run time and initial military selection test (combination of fitness, Trainability score) were collected prior to commencement of infantry recruit training. Injury data were collected during the 26 week training period.

Results:

Incidence rate of MSKI over a 26 week training period was 41.28% (95 % CI: 37.28 - 45.40%). The injured group had a higher medial plantar pressure (p < 0.03), shorter time to peak heel rotation (p < 0.02), current smoking status (p < 0.001) and a slower 1.5 mile run time (p < 0.03). In contrast, there were no significant differences (p > 0.23) in lateral heel pressure, age, weight, height, BMI and military selection test. A logistic regression model predicted MSKI significantly (p= 0.03) with an accuracy of 34.50% of all MSK injury and 76.70% of the non-injured group with an overall accuracy of 69.50%.

Conclusion:

The logistic regression model combining the three risk factors was capable of predicting 34.5% of all MSKI. A specific biomechanical profile, slow 1.5 mile run time and current smoking status were identified as predictors of subsequent MSKI development. The proposed model could include evaluation of other potential risk factors and if validated then further enhance the specificity, sensitivity and applicability.

Exercise performance increase in smokeless tobacco-user athletes after overnight nicotine abstinence

The use of nicotine administered through smokeless tobacco (snus) has increased among athletes. The purpose of this study was to investigate the ergogenic effects of snus on aerobic performance during exercise until exhaustion in athletes after abstinence or satiety nicotine conditions. The study utilized a randomized, controlled, within-subject design experiment. Sixteen male snus-user athletes completed an exercise until exhaustion at a constant load of their 80% of V ˙ O 2 max (calculated by a maximal incremental test) in two separate sessions, corresponding to nicotine conditions: 12-hour overnight abstinence and satiety. A portion of 1 g of snus (~8 mg/g of nicotine) was administered 25 minutes before each experimental test. In each session, time to exhaustion (TTE), global rating of perceived exertion, cardiovascular and metabolic responses, and muscle and cerebral oxygenation were measured. Nicotine and cotinine analysis confirmed session conditions (abstinence or satiety). Snus induced a significant increase (+13.1%) of TTE following abstinence (24.1 ± 10.7 minutes) compared to satiety condition (20.9 ± 8.0 minutes; P = 0.0131). The baseline values revealed that abstinence of snus induced significant increase in the oxygenation of the muscular tissues (+4%), in metabolic values and in cardiovascular parameters, when compared to satiety condition. Our results indicate an increase of exercise performance (+13.1% TTE) due to snus administration in an abstinence condition. Considering that twelve hours of abstinence from snus-contained nicotine affected metabolic, cardiovascular and muscular tissue oxygenation, we suggest that snus administration at test time might relieve these withdrawal changes and yield an increase in time to exhaustion.

Assessment of hand superficial oxygenation during ischemia/reperfusion in healthy subjects versus systemic sclerosis patients by 2D near infrared spectroscopic imaging

BACKGROUND AND OBJECTIVE

Patients affected by systemic sclerosis (SSc) develop functional and structural microcirculatory dysfunction, which progressively evolves towards systemic tissue fibrosis (sclerosis). Disease initially affects distal extremities, which become preferential sites of diagnostic scrutiny. This pilot investigation tested the hypothesis that peripheral microcirculatory dysfunction in SSc could be non-invasively assessed by 2D Near Infrared Spectroscopic (NIRS) imaging of the hand associated with Vascular Occlusion Testing (VOT). NIRS allows measurement of hemoglobin oxygen saturation (StO₂) in the blood perfusing the volume tissue under scrutiny.

METHODS

In five normal volunteers and five SSc patients we applied a multispectral oximetry imaging device (Kent camera, Kent Imaging, Calgary, Canada) to acquire StO₂ 2D maps of the whole hand palm during baseline, ischemia and reperfusion phase.

RESULTS

We found significant differences between controls and SSc patients in basal StO₂ (82.80 ± 2.51 vs 65.44 ± 7.96%, p = 0.0016), minimum StO₂ (59.35 ± 4.29 vs 40.73 ± 6.47%, p = 0.0007), final StO₂ (83.83 ± 4.09 vs 68.84 ± 11.41%, p = 0.02) and time to maximum StO₂ (40 ± 12.25 vs 62 ± 4.47 s, p = 0.005).

CONCLUSIONS

This is, to our knowledge, the first application of 2D NIRS imaging of the whole hand to the investigation of microvascular dysfunction in systemic sclerosis. The image processing presented here considered the StO₂ in the entire hand allowing a comprehensive view of the spatial heterogeneity of microvascular dysfunction.

Cerebral oxygenation and sympathetic responses to smoking in young and middle-aged smokers

This study examined the effects of acute tobacco smoking on cerebral oxygenation and autonomic function in 28 male, habitual smokers of shorter young smokers (YSM) or longer middle-aged smokers (MSM) smoking history. Following baseline testing, participants undertook a smoking protocol involving the consumption of two cigarettes within 15 min. Measures of cerebral oxygenation and autonomic function were collected before, during, and 0 min, 30 min, 1 h, and 4 h post-smoking. Tissue saturation index (TSI) for MSM was greater than YSM during cigarette consumption ( p < 0.05). Moreover, MSM observed significant within-group changes for TSI during and post-cigarette consumption ( p < 0.05). Further, MSM observed an increase in low frequency (LF) band from 30 min to 1 h post-consumption, followed by a decline, whereas elevations above MSM were observed in YSM at 4 h ( p < 0.05). Both MSM and YSM showed a decrease in high-frequency (HF) band post-cigarette, while increased LF/HF ratio post-consumption was observed in YSM. A decline in the standard deviation of RR intervals, post-cigarette consumption was evident in MSM ( p < 0.05). Moreover, the root mean square of RR interval in both groups similarly decreased following cigarette consumption ( p < 0.05). Acute smoking affects heart rate variability, suggestive of vagal withdrawal, and maybe indicate an effect of smoking history. Additionally, prolonged smoking history alters cerebral microcirculatory responses to acute tobacco exposure in MSM.

Microcirculatory alterations during continuous renal replacement therapy in ICU: A novel view on the 'dialysis trauma' concept

OBJECTIVE

The purpose of this study was to evaluate microcirculation over 24 h renal replacement therapy (CRRT) in critically ill patients.

METHODS

We conducted a single-center, prospective, observational study, measuring microcirculation parameters, monitored by near infrared spectroscopy (NIRS) before hemodiafiltration onset (H0), and at six (H6) and 24 h (H24) during CRRT in critically ill patients. Serum Cystatin C (sCysC) and soluble (s)E-selectin levels were measured at the same time points. Twenty-eight patients [19 men (68%)] were included in the study.

RESULTS

Tissue oxygen saturation (StO2, %) [76.5 ± 12.5 (H0) vs 75 ± 11 (H6) vs 70 ± 16 (H24), p = 0.04], reperfusion rate, indicating endothelial function (EF, %/sec) [2.25 ± 1.44 (H0) vs 2.1 ± 1.8 (H6) vs 1.6 ± 1.4 (H24), p = 0.02] and sCysC (mg/L) [2.7 ± 0.8 (H0) vs 2.2 ± 0.6 (H6) vs 1.8 ± 0.8 (H24), p < 0.0001] significantly decreased within the 24 h CRRT. Change of EF positively correlated with changes of sCysC within 24 h CRRT (r = 0.464, p = 0.013) while in patients with diabetes the change of StO2 correlated with dose (r = − 0.8, p = 0.01). No correlation existed between hemoglobin and temperature changes with the deteriorated microcirculation indices. sE-Selectin levels in serum were elevated; no difference was established over the 24 h CRRT period. A strong correlation existed between the sE-Selectin concentration change at H6 and H24 and the mean arterial pressure change in the same period (r = 0.77, p < 0.001).

CONCLUSIONS

During the first 24 h of CRRT implementation in critically ill patients, deterioration of microcirculation parameters was noted. Microcirculatory alterations correlated with sCysC changes and with dose in patients with diabetes.

Changes in skeletal muscle microcirculation after a hemodialysis session correlates with adequacy of dialysis

Background

Monitoring of the microcirculation may add additional information in terms of improving the adequacy of hemodialysis (HD) for patients. Withdrawal of liquid and complement activation during a HD session reduces the external pressure on the microcirculation and leads to an increased dilatation of the peripheral capillaries. The purposes of this study were to assess the effect of a single HD or hemodiafiltration session on the thenar microcirculation in patients with end-stage renal disease (ESRD) with or without diabetes, investigate the possible relationship between changes in the microcirculation and adequacy of dialysis (including Kt/V and parameters indicating secondary hyperparathyroidism), and compare microcirculation measurements obtained from patients with ESRD and those from healthy controls.

Methods

This pilot prospective observational study including eleven patients with ESRD on maintenance HD (nine men of mean age 73±10.5 years, ten [91%] with hypertension), nine patients with ESRD on maintenance hemodiafiltration (six men of mean age 65.5±13.2 years, five [55.5%] with diabetes and four [44.5%] with hypertension), and eight healthy volunteers. Two paired microcirculation assessments were recorded for each HD patient before and after a dialysis session. Near infrared spectroscopy and the vascular occlusion test were used to assess the microcirculation, and blood work samples were collected before and after dialysis when the pump slowed down.

Results

Patients with ESRD showed an increase in thenar cell metabolism at rest after a 4-hour HD session, and changes in cell metabolism correlated with the Kt/V of the session. Pre-dialysis tissue oxygen saturation over the 4-hour HD session correlated with pre-dialysis serum calcium and parathyroid hormones. Vascular reactivity was lower in ESRD patients receiving HD or hemodiafiltration than in healthy controls.

Conclusion

Improvement in skeletal muscle microcirculation noted after a HD session was related to adequacy of dialysis. Evaluation of the microcirculation may provide additional information for management of patients on HD and identify novel targets for treatment. These preliminary findings need to be tested using a larger data set.

Noninvasive assessment of peripheral microcirculation by near-infrared spectroscopy: a comparative study in healthy smoking and nonsmoking volunteers

Smokers are exposed to early endothelial dysfunction. This microcirculatory damage can be demonstrated by near-infrared spectroscopy (NIRS). The aim of this study was to compare microvascular reactivity by NIRS during a dynamic vascular occlusion test in healthy smokers and nonsmokers volunteers. Twenty healthy volunteers (10 men, 10 women), aged from 22 to 38 years old, were included after approval of the local Ethics Committee and divided into two groups: smokers (n = 10) and nonsmokers (n = 10). Tissue oxygen saturation (StO2) was measured at the level of each individual's calves during an ischemia and reperfusion test. In addition, during the ischemia phase, the slope of decline in StO2 was determined. Therefore, for each group, we were able to deduce the speed of desaturation (ΔStO2/ischemia time). The same was applied for resaturation rates during the reperfusion phase (ΔStO2/reperfusion time). StO2 values were comparable at all experimental steps between smokers and nonsmokers. During the vascular occlusion test, rates of desaturation were the same between smokers and nonsmokers [respectively 3.7%·min(-1) (range 2.5-12.6) and 3.7%·min(-1) (range 1.8-15.1); p = 0.50]. It was the same for the rate of resaturation [smokers 30.4%·min(-1) (range 14.2-51.6) and nonsmokers 30.5%·min(-1) (range 18.6-44.5); p = 0.82]. NIRS study of microvascular reactivity during a dynamic vascular occlusion test did not reveal any difference between smokers and nonsmokers. Therefore, NIRS could not be sensitive enough to highlight endothelial dysfunction in healthy subjects exposed to tobacco smoke.

Microcirculation in Pregnancy

The microcirculation, like all physiological systems undergoes modifications during the course of pregnancy. These changes aid the adaption to the new anatomical and physiological environment of pregnancy and ensure adequate oxygen supply to the fetus. Even though the microcirculation is believed to be involved in major pregnancy related pathologies, it remains poorly understood. The availability of safe and non-interventional technologies enabling scientists to study the intact microcirculation of the pregnant patient will hopefully expand our understanding. In this article we review the physiological changes occurring in the microcirculation during pregnancy and the role of the microcirculation in gestational related pathologies. We will also describe the available techniques for the measurement and evaluation of the microcirculation. Lastly we will highlight the possible fields in which these techniques could be utilized to help provide a clearer view of the microcirculation in the pregnant woman.

Resuscitation after cardiac arrest in a septic porcine model: adding vasopressin vs epinephrine alone administration

Background

Vasopressin administration has been tested in cardiac arrest. However it has not been tested when cardiac arrest occurs in certain circumstances, as in sepsis, where it may have a major role. The aim of the study was to investigate survival after cardiac arrest in a septic porcine model compared with healthy animals and to explore the effectiveness of adding vasopressin vs epinephrine alone administration.

Methods

Thirty five healthy piglets of both genders were studied. The piglets were randomly assigned into three groups: group A (n = 8), group B (n = 14), group C (n = 13). Animals of groups B and C were given endotoxin to mimic a septic state before arrest. We applied the same resuscitation protocol to all pigs but we replaced the first dose of epinephrine with vasopressin in pigs of group C. Following surgical preparation and 30 min resting period, baseline measurements were recorded. In order to assess tissue oxygenation, we implemented Near Infrared Spectroscopy (NIRS) with the vascular occlusion technique (VOT) in thirteen lipopolysaccharide (LPS)-treated animals, occluding abdominal aorta and inferior vena cava. Afterwards, LPS (100 μg/kg) was infused in a 30 min period to animals of groups B and C and normal saline to group A. New NIRS measurements were obtained again. Subsequently, we provoked ventricular fibrillation (VF). After 3 min of untreated VF, open chest cardiopulmonary resuscitation (CPR) was performed manually. Primary end point was the restoration of spontaneous circulation (ROSC).

Results

The chance of ROSC for the groups A, B and C was 75%, 35.7%, and 30.7% respectively. A significant difference in ROSC was established between septic (group B + C) and non septic piglets (group A) (P = 0.046). Vasopressin administration had no effect in outcome. LPS administration decreased oxygen consumption rate, as assessed by NIRS, in peripheral tissues (22.6 ± 7.2. vs 18.5 ± 7.2, P = 0.07).

Conclusion

Septic piglets have fewer chances to survive after cardiac arrest. No difference in outcome was observed when the first dose of epinephrine was replaced with vasopressin to treat cardiac arrest in the LPS-treated animals.

Prefrontal hemodynamic changes during cigarette smoking in young adult smokers with and without ADHD

Individuals with attention-deficit/hyperactivity disorder (ADHD) have elevated smoking prevalence and reduced cessation rates compared to the general population. However, the effects of cigarette smoking on underlying brain activity in smokers with ADHD are not well characterized. Non-invasive near-infrared spectroscopy (NIRS) was used to characterize how cigarette smoking affects prefrontal brain hemodynamics in smokers with and without ADHD. Prefrontal changes of oxy- and deoxyhemoglobin (HbO2 and HHb) were measured in six male adult smokers with ADHD and six age- and gender-matched control smokers. NIRS measurements were separated into four sequential time intervals, i.e., before smoking, during smoking, after smoking, and during a breath hold. Prefrontal HbO2 was lower during smoking in smokers with ADHD compared to control smokers. More specifically, smokers with ADHD showed decreased prefrontal HbO2 during smoking compared to breath hold, before and after smoking periods. In contrast, control smokers showed increased prefrontal HbO2 from before smoking to breath hold. Decreased prefrontal HbO2 in smokers with ADHD may reflect a smoking-induced change in prefrontal brain activity and microvasculature, which is not found in smokers without ADHD. The lower prefrontal HbO2 may be a biomarker for increased susceptibility to tobacco smoke in smokers with ADHD. Smoking in individuals with ADHD may increase vasoconstriction of cerebral arteries in the prefrontal cortex, which may contribute to a reduction in HbO2. The findings highlight the importance of smoking cessation, in particular in those smokers who use nicotine to self-medicate ADHD symptoms.

Whey protein lycosome formulation improves vascular functions and plasma lipids with reduction of markers of inflammation and oxidative stress in prehypertension

Parameters reflecting cardiovascular health and inflammation were studied in a pilot clinical trial conducted on 40 patients with prehypertension. The patients were treated with a new proprietary formulation of a whey protein (WP) isolate embedded into lycopene micelles (WPL) during a 1-month period. Control groups received lycopene or WP as a singular formulation or placebo pills for the same period of time. Combined WPL formulation of whey protein and lycopene has caused multiple favorable changes in the cardiovascular function (including a tendency to the reduced systemic blood pressure), the plasma lipid profile, and the inflammatory status of patients with prehypertension, whereas singular formulations of the compounds and placebo did not have such an effect. The reduction of plasma triglycerides and cholesterol fractions and almost two-fold decline in C-reactive protein (CRP) and inflammatory oxidative damage (IOD) levels as well as an increase in nitric oxide (NO), tissue oxygenation (StO₂), and flow-mediated dilation values constitute the most significant benefit/outcome of the treatment with the combined formulation of whey protein and lycopene. The treatment did not affect the values of ankle-brachial index (ABI), body weight, and body mass index (BMI).

Reproducibility of near-infrared spectroscopy parameters measured during brachial artery occlusion and reactive hyperemia in healthy men

Near-infrared spectroscopy (NIRS) is a noninvasive technique evaluating microvascular function. The aim of this study was to assess the reproducibility of NIRS parameters during reactive hyperemia induced by a 5 min brachial artery occlusion. Twenty-four healthy young males (mean 34 ± 8 years old) had two microvascular function evaluations by NIRS over a 7 to 30-day period (mean 16 ± 10 days). Intra-subject and inter-observer reproducibility were evaluated with intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard error of measurement (SEM%) for every parameter. Mean NIRS parameters did not differ between both evaluations. Reproducibility was greatest for muscle oxygen consumption (ICC: 0.84; CV: 6.51%; SEM: 7.11%), time to basal O(2)Hb (ICC: 0.63, CV: 20.04%, SEM 27.22%), time to maximal O(2)Hb (ICC: 0.71; CV: 15.61%; SEM: 19.27%), peak of O(2)Hb (ICC: 0.63, CV: 6.68%, SEM 8.53%), time to maximal tHb (ICC: 0.73, CV: 19,61%, SEM 24.56%) and area under the O(2)Hb and tHb curves (ICC: 0.68, CV: 16.15%, SEM 22.93% and ICC: 0.62, CV: 18.59%, SEM 26.64%, respectively). Moreover, inter-observer reproducibility ranged from excellent to perfect (ICC from 0.85 to 1.00) for every parameter. NIRS parameters during reactive hyperemia are highly reproducible which enables their repeated measurement to study microvascular function in healthy subjects.

Microcirculation and macrocirculation in cardiac surgical patients

Background. The aim of our study was to investigate the relationship between microcirculatory alterations after open cardiac surgery, macrohemodynamics, and global indices of organ perfusion. Methods. Patients' microcirculation was assessed with near-infrared spectroscopy (NIRS) and the vascular occlusion technique (VOT). Results. 23 patients undergoing open cardiac surgery (11 male/12 female, median age 68 (range 28-82) years, EuroSCORE 6 (1-12)) were enrolled in the study. For pooled data, CI correlated with the tissue oxygen consumption rate as well as the reperfusion rate (r = 0.56, P < 0.001 and r = 0.58, P < 0.001, resp.). In addition, both total oxygen delivery (DO(2), mL/min per m(2)) and total oxygen consumption (VO(2), mL/min per m(2)) also correlated with the tissue oxygen consumption rate and the reperfusion rate. The tissue oxygen saturation of the thenar postoperatively correlated with the peak lactate levels during the six hour monitoring period (r = 0.50, P < 0.05). The tissue oxygen consumption rate (%/min) and the reperfusion rate (%/min), as derived from the VOT, were higher in survivors compared to nonsurvivors for pooled data [23 (4-54) versus 20 (8-38) P < 0.05] and [424 (27-1215) versus 197 (57-632) P < 0.01], respectively. Conclusion. Microcirculatory alterations after open cardiac surgery are related to macrohemodynamics and global indices of organ perfusion.

Skeletal muscle microcirculatory abnormalities are associated with exercise intolerance, ventilatory inefficiency, and impaired autonomic control in heart failure

BACKGROUND

Several skeletal muscle abnormalities have been identified in patients with chronic heart failure (CHF), including endothelial dysfunction. We hypothesized that skeletal muscle microcirculation, assessed by near-infrared spectroscopy (NIRS), is impaired in CHF patients and is associated with disease severity.

METHODS

Eighty-three stable patients with mild-moderate CHF (72 males, mean age 54 ± 14 years, body mass index 26.7 ± 3.4 kg/m(2)) and 8 healthy subjects, matched for age, gender and body mass index, underwent NIRS with the vascular occlusion technique and cardiopulmonary exercise testing (CPET) evaluation on the same day. Tissue oxygen saturation (StO(2), %), defined as the percentage of hemoglobin saturation in the microvasculature compartments, was measured in the thenar muscle by NIRS before, during and after 3-minute occlusion of the brachial artery. Measurements included StO(2), oxygen consumption rate (OCR, %/min) and reperfusion rate (RR, %/min). All subjects underwent a symptom-limited CPET on a cycle ergometer. Measurements included VO(2) at peak exercise (VO(2)peak, ml/kg/min) and anaerobic threshold (VO(2)AT, ml/kg/min), VE/VCO(2) slope, chronotropic reserve (CR, %) and heart rate recovery (HRR(1), bpm).

RESULTS

CHF patients had significantly lower StO(2) (75 ± 8.2 vs 80.3 ± 6, p < 0.05), lower OCR (32.3 ± 10.4 vs 37.7 ± 5.5, p < 0.05) and lower RR (10 ± 2.8 vs 15.7 ± 6.3, p < 0.05) compared with healthy controls. CHF patients with RR ≥9.5 had a significantly greater VO(2)peak (p < 0.001), VO(2)AT (p < 0.01), CR (p = 0.01) and HRR(1) (p = 0.01), and lower VE/VCO(2) slope (p = 0.001), compared to those with RR <9.5. In a multivariate analysis, RR was identified as an independent predictor of VO(2)peak, VE/VCO(2) slope and HRR(1).

CONCLUSIONS

Peripheral muscle microcirculation, as assessed by NIRS, is significantly impaired in CHF patients and is associated with disease severity.

Smoking and atherosclerotic cardiovascular disease: part II: role of cigarette smoking in cardiovascular disease development

Potential mechanisms and biomarkers of atherosclerosis related to cigarette smoking - a modifiable risk factor for that disease - are discussed in this article. These include smoking-associated inflammatory markers, such as leukocytes, high-sensitivity C-reactive protein, serum amyloid A, ICAM-1 and IL-6. Other reviewed markers are indicative for smoking-related impairment of arterial endothelial function (transcapillary leakage of albumin, inhibition of endogenous nitric oxide synthase activity and reduced endothelium-dependent vasodilation) or point to oxidative stress caused by various chemicals (cholesterol oxidation, autoantibodies to oxidized low-density lipoprotein, plasma levels of malondialdehyde and F(2)-isoprostanes and reduced antioxidant capacity). Smoking enhances platelet aggregability, increases blood viscosity and shifts the pro- and antithrombotic balance towards increased coagulability (e.g., fibrinogen, von Willebrand factor, ICAM-1 and P-selectin). Insulin resistance is higher in smokers compared with nonsmokers, and hemoglobin A1c is dose-dependently elevated, as is homocysteine. Smoke exposure may influence the kinetics of markers with different response to transient or chronic changes in cigarette smoking behavior.

Characterization of tissue oxygen saturation and the vascular occlusion test: influence of measurement sites, probe sizes and deflation thresholds

Introduction

Tissue oxygen saturation (StO₂) and the vascular occlusion test (VOT) can identify tissue hypoperfusion in trauma and sepsis. However, the technique is neither standardized nor uses the same monitoring site. We hypothesized that baseline and VOT StO₂ would be different in the forearm (F) and thenar eminence (TH) and that different minimal StO₂ values during the VOT would result in different reoxygenation rates (ReO₂).

Methods

StO₂ and its change during the VOT were simultaneously measured in the F and TH, with 15 mm and 25 mm probes, using the 325 InSpectra monitor in 18 healthy, adult volunteers. Two VOTs were done to a threshold thenar StO₂ of 40% interchanging the 15 mm and 25 mm probes between sites. Two additional VOTs were done to thresholds of 50% and 30%. Baseline StO₂ (BaseO₂), the deoxygenation rate (DeO₂) and ReO₂ were compared between sites, probes and (%O₂/minute) thresholds. Results are presented as the median (interquartile range), P-value.

Results

BaseO₂, DeO₂, ReO₂, area under the curve and hyperemia duration values were different when comparing TH vs. F and 15 mm vs. 25 mm probes. ReO₂ was different between different thresholds for the TH and 15 mm probes. TH_{15 mm} vs. F_{15 mm}: BaseO₂, 90.4 (85.2, 93.5) vs. 85.2 (80.7, 90.2), P = 0.031; DO₂, -12.1 (-16.2, -11.3) vs. -8.5 (-10.3, -7.8), P = 0.011; ReO₂, 297.2 (213.7, 328.6), P < 0.0001; 15 mm vs. 25 mm probe: BaseO₂, 97.2 (89.4, 94.7) vs. 87.3 (81.7, 90.9), P = 0.016; DeO₂, -18.0 (-24.1, -14.8) vs. -9.9 (-15.3, -6.5), P < 0.0001; and ReO₂, 401.6 (331.7, 543.2) vs. 160.5 (132.3, 366.9), P = 0.012, respectively. TH_{15 mm} vs. TH_{25 mm}: BaseO₂, P = 0.020; DeO₂, P < 0.0001; and ReO₂, P < 0.0001. Threshold StO₂ values (15 mm probe only): ReO₂, P = 0.003; DeO₂, P = 0.60. ReO₂ at 40% and 50% StO₂ thresholds, P = 0.01.

Conclusions

BaseO₂, DeO₂ and ReO₂ were different when measured in different anatomical sites (F and TH) and with different probe sizes, and ReO₂ was different with differing VOT release StO₂ threshold values. Thus, standardization of the site, probe and VOT challenge need to be stipulated when reporting data.

Assessment of tissue oxygen saturation during a vascular occlusion test using near-infrared spectroscopy: the role of probe spacing and measurement site studied in healthy volunteers

Introduction

To assess potential metabolic and microcirculatory alterations in critically ill patients, near-infrared spectroscopy (NIRS) has been used, in combination with a vascular occlusion test (VOT), for the non-invasive measurement of tissue oxygen saturation (StO₂), oxygen consumption, and microvascular reperfusion and reactivity. The methodologies for assessing StO₂ during a VOT, however, are very inconsistent in the literature and, consequently, results vary from study to study, making data comparison difficult and potentially inadequate. Two major aspects concerning the inconsistent methodology are measurement site and probe spacing. To address these issues, we investigated the effects of probe spacing and measurement site using 15 mm and 25 mm probe spacings on the thenar and the forearm in healthy volunteers and quantified baseline, ischemic, reperfusion, and hyperemic VOT-derived StO₂ variables.

Methods

StO₂ was non-invasively measured in the forearm and thenar in eight healthy volunteers during 3-minute VOTs using two InSpectra tissue spectrometers equipped with a 15 mm probe or a 25 mm probe. VOT-derived StO₂ traces were analyzed for base-line, ischemic, reperfusion, and hyperemic parameters. Data were categorized into four groups: 15 mm probe on the forearm (F_{15 mm}), 25 mm probe on the forearm (F_{25 mm}), 15 mm probe on the thenar (T_{15 mm}), and 25 mm probe on the thenar (T_{25 mm}).

Results

Although not apparent at baseline, probe spacing and measurement site significantly influenced VOT-derived StO₂ variables. For F_{15 mm}, F_{25 mm}, T_{15 mm}, and T_{25 mm}, StO₂ ownslope was -6.4 ± 1.7%/minute, -10.0 ± 3.2%/minute, -12.5 ± 3.0%/minute, and -36.7 ± 4.6%/minute, respectively. StO₂ upslope was 105 ± 34%/minute, 158 ± 55%/minute, 226 ± 41%/minute, and 713 ± 101%/minute, and the area under the hyperemic curve was 7.4 ± 3.8%·minute, 10.1 ± 4.9%·minute, 12.6 ± 4.4%·minute, and 21.2 ± 2.7%·minute in these groups, respectively. Furthermore, the StO₂ parameters of the hyperemic phase of the VOT, such as the area under the curve, significantly correlated to the minimum StO₂ during ischemia.

Conclusions

NIRS measurements in combination with a VOT are measurement site-dependent and probe-dependent. Whether this dependence is anatomy-, physiology-, or perhaps technology-related remains to be elucidated. Our study also indicated that reactive hyperemia depends on the extent of ischemic insult.

Physical exercise improves the peripheral microcirculation of patients with chronic heart failure

PURPOSE

Patients with chronic heart failure (CHF) present with microcirculation alterations, partially attributed to endothelial dysfunction. Exercise training has been shown to induce beneficial effects in CHF patients. The aim of our study was to assess the effect of physical exercise on the microcirculation of CHF patients by near-infrared spectroscopy (NIRS).

METHODS

Sixteen consecutive stable CHF patients (men, n = 10; mean age = 50 +/- 12 years) participated in a 3-month rehabilitation program (3 sessions per week). All patients performed symptom-limited, ramp-incremental cardiopulmonary exercise testing on a cycle ergometer before and after the completion of the program. Measurements included peak oxygen uptake (VO2peak), VO2 at anaerobic threshold (AT), and first-degree slope of VO2 during the first minute of recovery (VO2/t slope). Tissue oxygen saturation was continuously measured by NIRS at the thenar muscle during a 3-minute vascular occlusion with a pneumatic cuff (occlusion technique) before and after the rehabilitation program.

RESULTS

The oxygen reperfusion rate (%/min) following the release of vascular occlusion increased significantly after the rehabilitation program (450 +/- 105 to 532 +/- 151, P = .004) as did vascular reactivity (from 27 +/- 13%/min to 39 +/- 21%/min, P = .006). In addition, there was a significant increase in VO2peak and AT (from 14.3 +/- 4.7 mL . kg . min to 16.7 +/- 6.3 mL . kg . min and from 9.5 +/- 3.6 mL . kg . min to 11.3 +/- 4 mL . kg . min, P = .007 and P = .012, respectively) as well as in VO2/t slope (from 0.35 +/- 0.17 to 0.51 +/- 0.07 mL . kg . min, P = .005).

CONCLUSIONS

Peripheral microcirculation of CHF patients measured by NIRS improved after the rehabilitation program. NIRS is a noninvasive technique that could be used to evaluate the effect of rehabilitation on the peripheral microcirculation of CHF patients.

Non-invasive Assessment of the Microcirculation in Critically Ill Patients

Sepsis is associated with abnormalities of muscle tissue oxygenation and of microvascular function. We investigated whether the technique of near-infrared spectroscopy can evaluate such abnormalities in critically ill patients and compared near-infrared spectroscopy-derived indices of critically ill patients with those of healthy volunteers.

We studied 41 patients (mean age 58±22 years) and 15 healthy volunteers (mean age 49±13 years). Patients were classified into one of three groups: systemic inflammatory response syndrome (SIRS) (n=21), severe sepsis (n=8) and septic shock (n=12). Near-infrared spectroscopy was used to continuously measure thenar muscle oxygen saturation before, during and after a three-minute occlusion of the brachial artery via pneumatic cuff.

Oxygen saturation was significantly lower in patients with SIRS, severe sepsis or septic shock than in healthy volunteers. Oxygen consumption rate during stagnant ischaemia was significantly lower in patients with SIRS (23.9±7.7%/minute, P <0.001), severe sepsis (16.9±3.4%/minute, P <0.001) or septic shock (14.8±6%/minute, P <0.001) than in healthy volunteers (35.5±10.6%/minute). Furthermore, oxygen consumption rate was significantly lower in patients with septic shock than patients with SIRS. Reperfusion rate was significantly lower in patients with SIRS (336±141%/minute, P <0.001), severe sepsis (257±150%/minute, P <0.001) or septic shock (146±101%/minute, P <0.001) than in healthy volunteers (713±223%/minute) and significantly lower in the septic shock than in the SIRS group.

Near-infrared spectroscopy can detect tissue oxygenation deficits and impaired microvascular reactivity in critically ill patients, as well as discriminate among groups with different disease severity.

Short-term systemic effect of electrical muscle stimulation in critically ill patients

BACKGROUND

Our study assessed the short-term effect of electrical muscle stimulation (EMS) of the lower extremities on the thenar muscle microcirculation of patients who are critically ill.

METHODS

Twenty-nine hospital ICU patients (19 men; mean [+/- SD] age, 58 +/- 19 years; mean acute physiology and chronic health evaluation score, 17 +/- 5; mean sequential organ failure assessment score, 9 +/- 3) underwent a 45-min session of EMS of the lower extremities. BP and heart rate were measured, and blood samples were retrieved. Tissue oxygen saturation (Sto(2)) was assessed with near infrared spectroscopy at the thenar muscle with a vascular occlusion before and after EMS. A control group of six patients who were critically ill (4 men; mean age, 50 +/- 19 years) also were included in the study.

RESULTS

The mean Sto(2) did not differ significantly before and after the EMS session (81 +/- 16% vs 83 +/- 16%, respectively). The oxygen consumption rate during vascular occlusion differed significantly before the beginning and at the end of the session (20 +/- 9%/min vs 22 +/- 9%/min, respectively; p < 0.05). The reperfusion rate differed significantly before the beginning and at the end of the session (299 +/- 177%/min vs 375 +/- 182%/min, respectively; p < 0.05). Heart rate increased significantly at the end of the session (94 +/- 16 beats/min vs 99 +/- 16 beats/min, respectively; p < 0.05) as did systolic BP (127 +/- 21 mm Hg vs 133 +/- 23 mm Hg; p < 0.05, respectively). The Sto(2) value did not differ between the two measurements in control patients.

CONCLUSION

The data suggest that EMS has a systemic effect on microcirculation. These results suggest that further studies are needed to explore the potential use of EMS as a preventive and rehabilitation tool in critically ill patients.

Inotropic agents improve the peripheral microcirculation of patients with end-stage chronic heart failure

BACKGROUND

Skeletal muscle microcirculation impairment in patients with chronic heart failure (CHF) seems to correlate with disease severity. We evaluated the microcirculation by near-infrared spectroscopy (NIRS) occlusion technique before and after inotropic infusion.

METHODS

We evaluated 25 patients with stable CHF, 30 patients with end-stage CHF (ESCHF) receiving treatment with intermittent infusion of inotropic agents, and 12 healthy subjects. Thenar muscle tissue oxygen saturation (StO(2)%) was measured noninvasively by NIRS before, during, and after 3-minute occlusion of the brachial artery (occlusion technique) in all subjects and in patients with ESCHF before and after 6 hours of inotropic infusion (dobutamine and/or levosimendan) or placebo (N = 5).

RESULTS

Patients with ESCHF or CHF presented significantly lower StO(2)% than healthy subjects (74.5% +/- 7%, 78.6% +/- 6%, and 85% +/- 5%, respectively; P = .0001), lower oxygen consumption rate during occlusion (24.6% +/- 8%/min, 28.6% +/- 10%/min, and 38.1% +/- 11.1%/min, respectively; P = .001), and lower reperfusion rate (327% +/- 141%/min, 410% +/- 106%/min, and 480% +/- 133%/min, respectively; P = .002). After 6 hours of inotropic infusion, patients with ESCHF showed significantly increased StO(2)% (74.5% +/- 7% to 82% +/- 9%, P = .001), oxygen consumption rate (24.6% +/- 8%/min to 29.3% +/- 8%/min, P = .009), and reperfusion rate (327% +/- 141%/min to 467% +/- 151%/min, P = .001). No statistical difference was noted in the placebo group.

CONCLUSION

Peripheral muscle microcirculation as assessed by NIRS is impaired in patients with CHF. This impairment is partially reversed by infusion of inotropic agents in patients with ESCHF.