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The problem of accuracy of intraocular pressure (IOP) measurement using Goldmann Applanation Tonometry (GAT) after a refractive surgery is still unresolved. In this study a numerical simulation of refractive surgery and GAT is proposed as a method to evaluate accuracy of the correction formula for GAT reading after changes in corneal curvature and thickness. In the finite element analysis the effect of the corneal shell buckling was taken into account. This effect is responsible for the nonlinear relation of Goldmann applanation tonometer measurement and intraocular pressure. Goldmann applanation tonometry was simulated for different ablation depths and values of intraocular pressure levels. The results of the simulation indicate a strong relation between the Goldmann applanation reading and the intraocular pressure level for values greater than nominal (about 16 mmHg). The estimation error of the intraocular pressure after changes in corneal geometry, is lower than 1 mmHg for IOP = 32 mmHg and lower than 3 mmHg for IOP = 48 mmHg. The proposed correction formula of Goldmann applanation tonometry occurred to be useful in the cases after the corneal refractive surgery regardless of the intraocular pressure values and ablation depth. • Accuracy of IOP measurement after refractive surgery still unresolved problem for ophthalmology. • Numerical experiment was proposed as a method of determining the correction for GAT reading. • The eye model, including buckling of the corneal shell, allows for accurate GAT simulation. • The equation derived from this model, provides correction to GAT readings after refractive surgery. [ABSTRACT FROM AUTHOR]

Abstract Background Studies of air pollution exposure and arterial stiffness have reported inconsistent results and large studies employing the reference standard of arterial stiffness, carotid-femoral pulse-wave velocity (CFPWV), have not been conducted. Aim To study long-term exposure to ambient fine particles (PM 2.5), proximity to roadway, and short-term air pollution exposures in relation to multiple measures of arterial stiffness in the Framingham Heart Study. Methods We assessed central arterial stiffness using CFPWV, forward pressure wave amplitude, mean arterial pressure and augmentation index. We investigated long-and short-term air pollution exposure associations with arterial stiffness with linear regressions using long-term residential PM 2.5 (2003 average from a spatiotemporal model using satellite data) and proximity to roadway in addition to short-term averages of PM 2.5 , black carbon, particle number, sulfate, nitrogen oxides, and ozone from stationary monitors. Results We examined 5842 participants (mean age 51 ± 16, 54% women). Living closer to a major roadway was associated with higher arterial stiffness (0.11 m/s higher CFPWV [95% CI: 0.01, 0.22] living <50 m vs 400 ≤ 1000 m). We did not observe association between arterial stiffness measures and long-term PM 2.5 or short-term levels of PM 2.5 , particle number, sulfate or ozone. Higher levels of black carbon and nitrogen oxides in the previous days were unexpectedly associated with lower arterial stiffness. Conclusions Long-term exposure to PM 2.5 was not associated with arterial stiffness but positive associations with living close to a major road may suggest that pollutant mixtures very nearby major roads, rather than PM 2.5 , may affect arterial stiffness. Furthermore, short-term air pollution exposures were not associated with higher arterial stiffness. Highlights • Living nearby a major road was associated with higher arterial stiffness. • Particle matter measured by satellite was not associated with arterial stiffness. • No associations were observed for short-term exposure to air pollution. [ABSTRACT FROM AUTHOR]

Abstract In this study, an analysis of the comparative effect of intravenous medetomidine, tramadol, and medetomidine combined with tramadol on the intraocular pressure in donkeys was conducted. In an experimental randomized prospective study, 24 adult donkeys devoid of ophthalmic defects were allocated randomly into four groups (six each). The first group received medetomidine hydrochloride (MED) intravenously at 0.007 mg kg−1, and the second group received tramadol hydrochloride (TRA) at 2 mg kg−1. The third group received a combination of MED and TRA at the same dose rates. However, the fourth group received 10 mL of 0.9% normal saline. Intraocular pressure values, heart rate, respiratory rate, and body temperature were measured before treatment (T0) and at 5, 15, 30, 45, 90, and 120 minutes after treatment. Donkeys treated with MED alone or MED/TRA combination exhibited a significant (P <.05) decrease in heart rate and respiratory rate at T5 until T90 compared with tramadol and normal saline. Intraocular pressure significantly (P <.001) decreased in donkeys treated with MED or MED/TRA combination in comparison with TRA and normal saline at T5 to T90. The highest reduction in IOP values in both treated groups was observed at T30 in the right and left eyes ([11.30 ± 0.94 and 10.59 ± 0.51 mmHg, MED groups, respectively] and [12.80 ± 0.65 and 12.30 ± 0.58 mmHg, MED/TRA groups, respectively]). In conclusion, medetomidine alone or in combination with tramadol could decrease the IOP values in healthy donkeys. Therefore, it may be used safely as a preoperative analgesic for intraocular surgery. Highlights • Effect of medetomidine, tramadol and their combination on IOP in donkeys was evaluated. • Twenty-four adult donkeys were used in an experimental randomized prospective study. • Medetomidine/tramadol combination induced decrease of IOP than other treatments. • Medetomidine/tramadol combination induced a significant decrease in heart and respiratory rates. [ABSTRACT FROM AUTHOR]

Described here is a new method for determination of carotid-femoral pulse wave velocity (PWV) based on arterial diameter waveform recording by an ultrasound system. The study was carried out on 120 consecutive patients. Carotid-femoral PWV was determined using a tonometric technique (PWVpp, PulsePen, DiaTecne, Milan, Italy) and an echotracking ultrasound system (PWVet, E-Track, Aloka, Tokyo, Japan). The relationship between PWVpp and PWVet was evaluated by linear regression and Bland-Altman analysis. There was excellent agreement between PWVet and PWVpp (Pearson's r = 0.94, 95% confidence interval: 0.91-0.96, p < 0.0001; PWVet = 0.88 × PWVpp + 0.57). The Bland-Altman plot revealed an offset of -0.33 m/s with limits of agreement from -2.21 to 1.54 m/s. The coefficients of variation for within-subject repeatability between PWVet and PWVpp had were 5.79% and 8.47%, respectively, without significant differences in the Bland-Altman analysis. The results suggest that echotracking technology can provide a reliable estimate of aortic stiffness comparable to that of the tonometric techniques. [ABSTRACT FROM AUTHOR]

Objective: Digital ulcers (DU) are a burden in systemic sclerosis (SSc). Microangiopathy is a cardinal feature of SSc that plays a critical role in the development of DU. However, whether injury of medium or large vessels also contributes to DU in SSc remains controversial.Methods: To measure concomitantly in SSc patients with and without active DU: (i) the Augmentation Index of the reflected wave (Aix_75) by radial applanation tonometry, an index of small and medium arterial function; (II) the aortic pulse wave velocity (PWV), a marker of large vessel injury (aortic stiffness).Results: Sixty-three consecutive SSc patients were included (49 females, aged 60 [49-65] years, disease duration of 8.5 [5-13] years), including 10 (15.9%) with active DU. Patients with active DU versus those without had increased Aix_75 (35% [28-38] versus 28% [20-34], P=0.041) whereas no difference existed in PWV (7.0m/s [6.7-10.1] versus 7.6m/s [6.8-8.7], P=0.887), in systolic, diastolic, as well as aortic pulse pressure (P=0.126, 0.592, and 0.161, respectively). When compared to patients in the low tertile, patients having Aix_75 in the highest tertile had 10-fold more DU (OR=10.23; 95% CI 1.12 to 93.34, P=0.039).Conclusion: The presence of DU is associated with increased Aix_75 whereas there is no relation with PWV. These data suggest that small and medium arteries are involved in the occurrence of DU whether large vessel stiffness does not contribute. Whether Aix_75 is predictive of further DU remained to be studied. [ABSTRACT FROM AUTHOR]

Arterial hypertension can lead to the progressive deterioration of the left ventricular (LV) performance. The aim of this study was to estimate the relation of global longitudinal systolic strain (GLSS) with central and systemic hemodynamics assessed by applanation tonometry and impedance cardiography in 125 hypertensive patients. Those with more impaired GLSS characterized with 1/worse diastolic function (mitral inflow early phase (E) to mitral septal annulus early diastolic velocity (e') ratio, 8.0 vs. 7.0, P = .014); 2/lower LV performance (cardiac index, 3.14 vs. 3.64 l/min/m 2 ; P = .007), and 3/higher afterload (systemic vascular resistance index, 2506 vs. 2107 dyn s m 2 /cm 5 ; P = .008). No relevant differences in, that is, gender, age, blood pressure, LV mass index, left chambers dimensions, and central blood pressure characteristics were identified. The results revealed that impaired GLSS is related to LV diastolic dysfunction and altered hemodynamics which may be markers of early systolic LV dysfunction related to arterial hypertension. [ABSTRACT FROM AUTHOR]

Abstract: Body weight support (WS) during treadmill exercise is used to rehabilitate orthopedic/neurological patients. WS lowers musculoskeletal strain and load. It compresses the lower body and increases intrathoracic volume. We studied short-term effects of WS on wave reflection indices using applanation tonometry during progressive WS of 25%, 50%, and 75% of body weight in 25 healthy men. WS decreased mean heart rate from 79 to 69 beats/min (P < .001). Peripheral and central mean arterial, systolic, and pulse pressures (PP) remained unchanged. There was a trend toward lower peripheral and central diastolic pressure. PP amplification ratio decreased significantly (P = .005). Reflected wave characteristics: Augmented pressure and index increased in a stepwise manner with WS (both P < .001). Both ejection duration and systolic duration of the reflected pressure wave (Ätr) increased progressively (both P < .001). The round-trip travel time (Δtp) was unchanged. Left ventricular workload and oxygen demand: Left ventricular wasted pressure energy increased (P < .001), and the subendocardial viability ratio decreased (P = .005), whereas the tension time index remained unchanged. In normal men, WS acutely decreases the PP amplification ratio, increases the amplitude and duration of the reflected aortic pressure wave, and increases measures of wasted left ventricular pressure energy and oxygen demand. [Copyright &y& Elsevier]

Abstract: Recent reports that habitual marathon runners demonstrate higher levels of stiffness and cardiovascular risk factors have been of great interest to the medical and scientific community. Ultra-marathon running, that is any distance >42.2km, is increasing in popularity; however, little is known regarding the physiological effects of the sport's unique training and racing practices on vascular health. Objectives: To characterize and compare the arterial compliance of male long-term (>5years) ultra-marathoners with recreationally active controls, and examine the associations of training related practices with systemic arterial compliance. Design: We employed a case-control comparison design using long-term habitual ultra-marathon runners (n =18) and an age matched cohort of normative recreationally active males. Methods: Arterial compliance was measured at rest using radial applanation tonometry (CR-2000, HDI) for diastolic pulse contour analysis. Compliance was compared with normative data, participant characteristics, and associated exercise parameters. Results: In representative ultra-endurance runners, large artery compliance of long-term participants was reduced compared with physically active age-matched controls (p =0.03) and is related to select training variables. Specifically, in a representative subset for whom we obtained detailed training data, decreased compliance was related to longer typical running distance per training session (r =−0.72, p =0.03); however, more broad definitions of frequency, intensity, and duration revealed no association for the runners as a whole. Conclusions: Given the known associations of arterial stiffness with future cardiovascular events, ultra-endurance runners may be at an increased risk of a cardiovascular event compared with their normally active counterparts. [Copyright &y& Elsevier]

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Abstract: Elevated central systolic blood pressure (BP) increases the risk of cardiovascular events and appears superior to peripheral BP for long term risk prediction. The objective of this study was to identify demographic and clinical factors associated with central pressures in patients with uncomplicated hypertension. We prospectively examined peripheral BP, central aortic BP, and arterial wall properties and wave reflection in 57 subjects with uncomplicated essential hypertension in the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) Study. Significant predictors of central SBP included height, smoking status, heart rate (HR), and peripheral systolic BP (SBP), while central diastolic BP (DBP) was explained by peripheral DBP and HR. These variables accounted for nearly all of the variability in central SBP and central DBP (R2 = 0.94 and R2 = 0.98, respectively). Central pulse pressure variability was largely explained by gender, ex-smoking status, HR, peripheral SBP, and peripheral DBP (R2 = 0.94). Central augmented pressure had a direct relationship with smoking status, peripheral SBP, and duration of hypertension, whereas it was indirectly related to height, HR, and peripheral DBP. Easily obtainable demographic and clinical factors are associated with central pressures in essential hypertensive persons. These relationships should be considered in future studies to improve assessment of BP to reduce cardiovascular risk and mortality. [Copyright &y& Elsevier]

Background and objectives: Non-invasive methods based on applanation tonometry have been proposed to estimate central blood pressure. However, the accuracy of these methods hasn't been systematically examined. Methods: We performed a systematic review and meta-analysis of studies comparing estimated and invasively measured central BP. Results: Sufficient data were available in 22 studies for meta-analysis (857 subjects and 1167 measurements). Acquired arterial pressure waveforms in these studies were directly measured, calibrated to match invasive aortic mean BP and diastolic BP or calibrated to match brachial BP measured with a sphygmomanometer, cuff BP. Of the former 2 conditions, the errors of estimated central BP were small with a mean and standard deviation of difference −1.1±4.1mm Hg (95% limits of agreement −9.1–6.9mm Hg) for central systolic BP; −0.5±2.1mm Hg (−4.6–3.6mm Hg) for central diastolic BP; and −0.8±5.1mm Hg (−10.8–9.2mm Hg) for central pulse pressure. However, the errors inflated to −8.2±10.3mm Hg (−28.4–12.0mm Hg) for central systolic BP, 7.6±8.7mm Hg (−9.5–24.6mm Hg) for central diastolic BP, and −12.2±10.4mm Hg (−32.5–8.1mm Hg) for central pulse pressure, when calibrated to cuff BP. The findings were still evident in subgroup analysis conducted with different central BP estimating methods and validated cuff BP monitors. Conclusion: Present tonometry-based central BP estimating methods are acceptable in theory, with small errors. However, based on current available evidence, there is substantial room for improvement in measurement accuracy of central BP when cuff BP is used to calibrate the peripheral waveforms. [ABSTRACT FROM AUTHOR]

Résumé: But de l’étude: L’analyse des ondes de pression est un instrument pour l’estimation des paramètres hémodynamiques centraux. La tonométrie d’applanation sur les artères radiale et/ou carotide mesure les courbes de pression. Les appareils disponibles sur le marché ont été validés contre des cathéters invasifs, en montrant une bonne concordance des patterns des harmoniques. Dans une étude précédente, nous avons observé des différences sur le deuxième pic radial (rSBP2), entre deux appareils : le SphygmoCor (AtCor, Australie) et le PulsePen (DiaTechne, Italie). Le but de notre étude est de rechercher les différences des signaux radial et carotidien entre les deux appareils. Patients et méthodes: Nous avons mesuré les courbes de pression radiales et carotidiennes chez 38 patients chez qui les pressions systolique et diastolique et la fréquence cardiaque présentaient des variations minimes. Résultats: Le rSBP2, la pression moyenne et l’index d’augmentation étaient différents, le SphygmoCor donnant des valeurs inférieures au PulsePen. L’index d’augmentation carotidien était similaire. La pression systolique carotidienne (cSBP) de PulsePen était plus élevée que SphygmoCor. Conclusion: Les sondes tonométriques de PulsePen et SphygmoCor ne sont pas équivalentes et donnent des formes différentes d’onde de pression. Ces différences ont des conséquences importantes sur des paramètres hémodynamiques calculés à partir de ces courbes, surtout vis-à-vis de l’artère radiale. D’autres études de comparaison invasive de courbes de pression pourraient définir quel appareil produit des ondes de pression valides. La comparaison des données obtenues avec ces deux appareils devrait nous inciter à la prudence. [ABSTRACT FROM AUTHOR]

Abstract: This study was conducted to determine effects of intravenous detomidine on intraocular pressure (IOP) readings obtained by applanation tonometry in clinically normal horses. Twenty horses were randomly divided into two groups of 10 each (treatment and control). All horses in the treatment group received intravenous detomidine alone (20 μg/kg). The horses in the control group received only intravenous saline (0.2 mL/100 kg). The IOP values were measured before the treatment (T0) and then at 5 (T5), 20 (T20), 60 (T60), and 120 (T120) minutes after drug administration in both groups. A significant decrease in IOP values was observed in both right and left eyes of the horses in the treatment group at T5, T20, and T60 in comparison with the baseline values (P < .001). The observed decrease was only statistically significant in the right eyes of the treatment group horses at T120 (P = .044). Mean IOP was not significantly altered at any time point during the treatment period compared with the baseline evaluations in both eyes of the horses in the control group. This study demonstrates that the use of intravenous detomidine lowers IOP quickly. [Copyright &y& Elsevier]

Abstract: Objectives: Left ventricular end systolic pressure (LV ESP) is important in assessing left ventricular performance and is usually derived from prediction equations. It is unknown whether these equations are accurate at rest or following exercise in a young, healthy population. Design: Measured LV ESP vs. LV ESP values from the prediction equations were compared at rest, 15min and 30min following peak aerobic exercise in 60 participants. Methods: LV ESP was obtained by applanation tonometry at rest, 15min post and 30min post peak cycle exercise. Results: Measured LV ESP was significantly lower (p <0.05) at all time points in comparison to the two calculated values. Measured LV ESP decreased significantly from rest at both the post15 and post30 time points (p <0.05) and changed differently in comparison to the calculated values (significant interaction; p <0.05). The two LV ESP equations were also significantly different from each other (p <0.05) and changed differently over time (significant interaction; p <0.05). Conclusions: The two commonly used prediction equations did not accurately predict either resting or post exercise LV ESP in a young, healthy population. Thus, LV ESP needs to be individually determined in young, healthy participants. Non-invasive measurement through applanation tonometry appears to allow for a more accurate determination of LV ESP. [Copyright &y& Elsevier]

The aorta stiffens with aging, a process that is accelerated by arterial hypertension. Decreased arterial compliance is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall. The use of different imaging techniques optimized for assessment of vascular elasticity and quantification of luminal and vessel wall parameters allows for a comprehensive and detailed view of the vascular system. In addition, several studies have also documented the prognostic importance of arterial stiffness (AS) in various populations as an independent predictor of cardiovascular morbidity and all-cause mortality. Measurement of AS by applanation tonometry with pulse-wave velocity has been the gold-standard method and is well-validated in large populations as a strong predictor of adverse cardiovascular outcomes. Because aortic stiffness depends on the prevailing blood pressure, effective antihypertensive treatment is expected to reduce it in proportion to the blood pressure reduction. Nevertheless, drugs lowering blood pressure might differ in their effects on structure and function of the arterial walls. This review paper not only will discuss the current understanding and clinical significance of AS but also will review the effects of various pharmacological and nonpharmacological interventions that can be used to preserve the favorable profile of a more compliant and less stiff aorta. [ABSTRACT FROM AUTHOR]

Abstract: Intraocular pressure (IOP) in the human eye as measured by a Goldmann applanation tonometer (GAT) is known to be affected by individual differences in central corneal thickness (CCT). However, data from clinical studies also show considerable scatter in the correlation between measured IOP and CCT. One possible implication of the large observed scatter is that the true IOP (IOPT) also depends significantly on individual variations in the material stiffness properties of the cornea. This hypothesis is explored and evaluated herein using computational simulation of applanation tonometry. A simplified 2D finite element model of the eye, which employs a calibrated nonlinear transversely isotropic material model for the cornea, is developed, and a series of GAT simulations is carried out to study the effect of geometry and material properties of the cornea on the IOP readings obtained via GAT. The results of this parametric study provide a simple correction equation, which quantifies the effect on measured IOP of variations in CCT and corneal material stiffness. In addition, several previously proposed IOP correction equations are compared with the one proposed here. [Copyright &y& Elsevier]

Abstract: Background: Aortic pressure waveforms are calculated non-invasively by applying generalized transfer functions (GTF) to tonometric radial pressure waveforms. Input errors mainly during acquisition and calibration of tonometric pressures are “transferred” to aortic pressure calculation. The present study aimed to quantify the proportion of specific input errors which is “transferred” by the GTFs in a wide range of hemodynamic conditions and for different error combinations in brachial systolic (SBP) and diastolic (DBP) blood pressure measurements. Methods: Aortic pulse wave analysis was performed in 103 subjects (52 normotensive and 51 untreated hypertensive) by the SphygmoCor® System. Each pressure waveform was initially calibrated by sphygmomanometrical brachial pressures. Isolated, parallel and reverse errors in brachial SBP/DBP from −10 to +10 mmHg were simulated, by recalibration of the recorded radial pressure waveforms, inducing specific “errors” of GTF-input values. For every recalculated aortic SBP and DBP, the difference from the initial estimated value was considered to represent the “transferred error” to the aortic pressure estimation. Results: Parallel errors by ±5 mmHg in both SBP and DBP resulted to an identical change in GTF-derived aortic pressures, as expected. When an overestimation in SBP by 5 mmHg and an underestimation in DBP by −5 mmHg occurred (reverse errors), almost 56% of this error (∼2.8 mmHg) was transferred. An isolated error in brachial SBP by ±5 mmHg was transmitted by 76% (∼3.8 mmHg) to GTF-derived aortic SBP. In subjects with mean blood pressure >117 mmHg or with heart rates <74 bpm, a greater percent of the calibration error was transferred to GTF-derived blood pressures. Conclusions: Input errors in brachial pressure values result in a quantifiable effect on transfer function output (aortic pressures). The percent of the “error transfer” by the GTFs depends on heart rate and BP levels, which should be taken into account when applying GTFs at populations with different hemodynamic conditions. [Copyright &y& Elsevier]

Abstract: Both increased arterial stiffness and atherosclerosis are risk factors for cardiovascular morbidity and mortality. We studied the relationship between aortic atherosclerosis, assessed by measuring maximal aortic intima–media thickness (MAIMT) on transesophageal echocardioagraphy and aortic stiffness, measured by applanation tonometry. Eighty-one patients (28 men, 53 women, mean age 61±13 years) referred for transesophageal echocardiography were studied. Augmentation index (AI) and carotid–radial pulse (PWV) wave velocity were measured using a SphygmoCor® tonometer (Atcor Med., Australia). MAIMT was correlated with AI and age (r =0.35, p =0.002 and r =0.36, p =0.001), respectively. There were no relations between MAIMT and either aortic pulse pressure (A-PP) (r =0.10, p =0.35) or PVW (r =−0.38, p =0.76). Multivariate regression analysis revealed that AI and age were independently related to MAIMT. In this middle-aged predominantly African-American population structural aortic atherosclerosis and aortic stiffness as measured by AI are age dependent and are inter-related, independent of age. [Copyright &y& Elsevier]