Effets de la perfusion de facteurs natriurétiques auriculaires synthétiques sur quelques flux régionaux chez le volontaire sain [Effect of synthetic atrial natriuretic factors on various regional blood flows in the healthy subject]

The effects of continuous infusions of 2 synthetic atrial natriuretic peptides Ile12-(3-28) (rANP) and Meth12-(3-28) (hANP) eicosahexapeptides on blood pressure, heart rate, skin blood flow, glomerular filtration rate, renal plasma flow, apparent hepatic blood flow, and carotid blood flow were evaluated in normal volunteers. A rANP infusion at increasing rates (1-40 micrograms/min) induced a decrease in blood pressure, an increase in heart rate and in skin blood flow linearly related to the dose administered. In contrast, hANP infusion at 1 microgram/min for 4 hours induced an initial increase followed by a secondary fall in skin blood flow without blood pressure changes. A 4-hour rANP infusion at 0.5 and 5 mcg/min did not alter glomerular filtration rate but induced a delayed and dose-related fall in renal plasma flow from 531 to 461 (p less than 0.05), and from 554 to 342 ml/min (p less than 0.001) respectively, with a consequential rise in the filtration fraction. The 5 mcg/min dose furthermore significantly reduced blood pressure following a latency period of 2.5 hours. A 2-hours rANP infusion at 0.5 micrograms/min induced a fall in apparent hepatic blood flow from 1,087 to 863 ml/min (p less than 0.01), without simultaneously altering blood pressure. Similarly, a 2-hour hANP infusion at 2 micrograms/min altered neither blood pressure nor carotid blood flow. In conclusion, ANP infusion induced changes in systemic and regional hemodynamics varying in direction, intensity and duration.

Effect of n-3 fatty acids on cerebral markers and the inflammatory response in sepsis

Introduction ICM+ software encapsulates our 20 years' experience in brain monitoring. It collects data from a variety of bedside monitors and produces time trends of parameters defi ned using confi gurable mathematical formulae. To date it is being used in nearly 40 clinical research centres worldwide. We present its application for continuous monitoring of cerebral autoregulation using near-infrared spectroscopy (NIRS). Methods Data from multiple bedside monitors are processed by ICM+ in real time using a large selection of signal processing methods. These include various time and frequency domain analysis functions as well as fully customisable digital fi lters. The fi nal results are displayed in a variety of ways including simple time trends, as well as time window based histograms, cross histograms, correlations, and so forth. All this allows complex information from bedside monitors to be summarized in a concise fashion and presented to medical and nursing staff in a simple way that alerts them to the development of various pathological processes. Results One hundred and fi fty patients monitored continuously with NIRS, arterial blood pressure (ABP) and intracranial pressure (ICP), where available, were included in this study. There were 40 severely headinjured adult patients, 27 SAH patients (NCCU, Cambridge); 60 patients undergoing cardiopulmonary bypass (John Hopkins Hospital, Baltimore) and 23 patients with sepsis (University Hospital, Basel). In addition, MCA fl ow velocity (FV) was monitored intermittently using transcranial Doppler. FV-derived and ICP-derived pressure reactivity indices (PRx, Mx), as well as NIRS-derived reactivity indices (Cox, Tox, Thx) were calculated and showed signifi cant correlation with each other in all cohorts. Errorbar charts showing reactivity index PRx versus CPP (optimal CPP chart) as well as similar curves for NIRS indices versus CPP and ABP were also demonstrated. Conclusions ICM+ software is proving to be a very useful tool for enhancing the battery of available means for monitoring cerebral vasoreactivity and potentially facilitating autoregulation guided therapy. Complexity of data analysis is also hidden inside loadable profi les, thus allowing investigators to take full advantage of validated protocols including advanced processing formulas.

Foot skin blood flow following infrainguinal revascularization for critical lower limb ischemia.

INTRODUCTION: The aim of this study was to assess the blood flow in the feet before and after lower limb revascularization using laser Doppler imaging (LDI). METHODS: Ten patients with critical lower limb ischemia were prospectively enrolled from June to October 2004. All patients underwent successful unilateral surgical interventions including above-knee bypass, distal bypass and endarterectomy. Skin blood flow (SBF) over the plantar surface of both forefeet and heels was measured by LDI 24h before and 10 days after revascularization, expressed in perfusion units (PU), and reported as mean+/-SD. RESULTS: Measurements in the forefoot and heel were similar. Before revascularization mean SBF was significantly lower in the ischemic foot (130+/-71 PU) compared to the contralateral foot (212+/-68 PU), p<0.05. After revascularization a significant increase of the SBF in the forefoot (from 135+/-67 to 202+/-86 PU, p=0.001) and hindfoot (from 148+/-58 to 203+/-83, p=0.001) was observed on the treatment side. However, a large decrease of the SBF was seen in forefoot and hindfoot on the untreated side (from 250+/-123 PU to 176+/-83 and from 208+/-116 to 133+/-40, p=0.001, respectively). CONCLUSION: This study confirms the benefits of revascularization in patients with nonhealing foot lesions due to critical limb ischemia. A significant increase of the SBF was observed on the treatment side. However, an unexpected decrease was observed on the untreated side.

Hemodynamic effects of sodium bicarbonate in critically ill neonates.

OBJECTIVE: To analyze the cardiovascular effects of sodium bicarbonate in neonates with metabolic acidosis. DESIGN: Prospective, open, non-randomized, before-after intervention study with hemodynamic measurements performed before and 1, 5, 10, 20, and 30 min after bicarbonate administration. SETTING: Neonatal intensive care unit, tertiary care center. PATIENTS: Sequential sample of 16 paralysed and mechanically ventilated newborn infants with a metabolic acidosis (pH < 7.25 in premature and < 7.30 in term infants, base deficit > -8). INTERVENTION: An 8.4% sodium bicarbonate solution diluted 1:1 with water (final osmolality of 1000 mOsm/l) was administered in two equal portions at a rate of 0.5 mmol/min. The dose in mmol was calculated using the formula "base deficit x body weight (kg) x 1/3 x 1/2". MEASUREMENTS AND RESULTS: Sodium bicarbonate induced a significant but transient rise in pulsed Doppler cardiac output (CO) (+27.7%), aortic blood flow velocity (+15.3%), systolic blood pressure (BP) (+9.3%), (+14.6%), transcutaneous carbon dioxide pressure (PtcCO2) (+11.8%), and transcutaneous oxygen pressure (PtcO2) (+8%). In spite of the PaCO2 elevation, pH significantly improved (from a mean of 7.24 to 7.30), and the base deficit decreased (-39.3%). Calculated systemic vascular resistance (SVR) (-10.7%) and diastolic BP (-11.7%) decreased significantly, while PaO2 and heart rate (HR) did not change. Central venous pressure (CVP) (+6.5%) increased only slightly. By 30 min after bicarbonate administration all hemodynamic parameters, with the exception of the diastolic BP, had returned to baseline. CONCLUSION: Sodium bicarbonate in neonates with metabolic acidosis induces an increase in contractility and a reduction in afterload.

Retinal vessel oxygen saturation and its correlation with structural changes in retinitis pigmentosa.

PURPOSE: To study the influence of retinal structural changes on oxygen saturation in retinitis pigmentosa (RP) patients. METHODS: Oximetry measurements were performed on 21 eyes of 11 RP patients and compared to 24 eyes of 12 controls. Retinal oxygen saturation was measured in all major retinal arterioles (A-SO₂) and venules (V-SO₂) with an oximetry unit of the retinal vessel analyser (IMEDOS Systems UG, Jena, Germany). Oximetry data were compared with morphological changes measured by Cirrus optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA, USA, macular thickness protocol). RESULTS: In RP patients, the retinal A-SO₂ and V-SO₂ levels were higher at 99.3% (p = 0.001, anova based on mixed-effects model) and 66.8% (p < 0.001), respectively, and the difference between the two (A-V SO₂) was lower at 32.5% (p < 0.001), when compared to the control group (92.4%; 54.0%; 38.4%, respectively). With the RP group, the A-V SO₂ correlated positively, not only with central macular thickness, but also with retinal thickness, in zones 2 and 3 (p = 0.006, p = 0.007, p = 0.014). CONCLUSION: These data indicate that oxygen metabolism was altered in RP patients. Based on our preliminary results, retinal vessel saturation correlated with structural alterations in RP. This method could be valuable in monitoring disease progression and evaluating a potential therapeutic response.

Changes in cerebral compartmental compliances during mild hypocapnia in patients with traumatic brain injury.

The benefit of induced hyperventilation for intracranial pressure (ICP) control after severe traumatic brain injury (TBI) is controversial. In this study, we investigated the impact of early and sustained hyperventilation on compliances of the cerebral arteries and of the cerebrospinal (CSF) compartment during mild hyperventilation in severe TBI patients. We included 27 severe TBI patients (mean 39.5 ± 3.4 years, 6 women) in whom an increase in ventilation (20% increase in respiratory minute volume) was performed during 50 min as part of a standard clinical CO(2) reactivity test. Using a new mathematical model, cerebral arterial compliance (Ca) and CSF compartment compliance (Ci) were calculated based on the analysis of ICP, arterial blood pressure, and cerebral blood flow velocity waveforms. Hyperventilation initially induced a reduction in ICP (17.5 ± 6.6 vs. 13.9 ± 6.2 mmHg; p < 0.001), which correlated with an increase in Ci (r(2) = 0.213; p = 0.015). Concomitantly, the reduction in cerebral blood flow velocities (CBFV, 74.6 ± 27.0 vs. 62.9 ± 22.9 cm/sec; p < 0.001) marginally correlated with the reduction in Ca (r(2) = 0.209; p = 0.017). During sustained hyperventilation, ICP increased (13.9 ± 6.2 vs. 15.3 ± 6.4 mmHg; p < 0.001), which correlated with a reduction in Ci (r(2) = 0.297; p = 0.003), but no significant changes in Ca were found during that period. The early reduction in Ca persisted irrespective of the duration of hyperventilation, which may contribute to the lack of clinical benefit of hyperventilation after TBI. Further studies are needed to determine whether monitoring of arterial and CSF compartment compliances may detect and prevent an adverse ischemic event during hyperventilation.

Combining blockers of the renin-angiotensin system or increasing the dose of an angiotensin II receptor antagonist in proteinuric patients: a randomized triple-crossover study.

Objective The goal of this study was to investigate whether increasing the dose of an angiotensin II receptor blocker (ARB) provides as much benefits as combining the ARB with an angiotensin-converting enzyme inhibitor (ACEI) in terms of blood pressure (BP) control and urinary albumin excretion (UAE) in hypertensive patients with a proteinuria.Methods We enrolled 20 hypertensive patients with proteinuric nephropathies and a reduced renal function in a randomized, 12-month, triple-crossover, prospective, open-label study to compare the effects of a regular dose of losartan (Los 100mg q.d., LOS100) vs. a high dose of losartan (Los 100mg b.i.d., LOS200) vs. losartan 100mg q.d. associated with lisinopril 20 mg q.d. (LOS100 + LIS20). Each treatment was given for 8 weeks with a 4-week initial run-in period and 2 weeks of washout between each treatment phases. 24 h UAE and ambulatory BP were measured during the running phase and at the end of each treatment period.Results Compared to pretreatment, 24 h SBP and DBP were reduced by 10/5 +/- 7/4 mmHg with LOS100 (P=0.023 vs. baseline) and, respectively, 13/6 +/- 12/5 mmHg with LOS200 (P=0.011) and 19/9 +/- 15/8 mmHg with LOS100+LIS20 (P < 0.01). UAE decreased significantly with LOS100 and to an even greater degree with LOS200 and LOS100+LIS20 (P < 0.01 vs. baseline for both and P=0.032, LOS100+LIS20 vs. LOS200). The combination had a greater impact in patients with a high baseline proteinuria as suggested by a nonparallel leftward shift of the relationship between the changes in UAE induced by the combination and those induced by LOS200. The high dose of losartan was better tolerated than the combination.Conclusion Increasing the dose of losartan from 100mg once daily to 100mg twice a day enables to obtain a greater decrease in BP and proteinuria and is better tolerated than combining the ARB with lisinopril, though the high dose appears to be slightly less effective than the combination in patients with a marked proteinuria. J Hypertens 29: 1228-1235 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Eficàcia de les intervencions infermeres per a l'autocontrol de la tensió arterial en persones hipertenses

Fonaments: La hipertensió és una malaltia crònica amb alta prevalença al món. Els estils de vidasaludables es relacionen directament amb aquesta patologia pel que el rol de la infermeria és clauen el desenvolupament d'eines i intervencions per millorar l'autocontrol dels pacients hipertensosmitjançant l'educació sanitària.Objectiu: És valorar l'eficàcia de les intervencions en consultes d'infermera per a l'autocontrol dela tensió arterial en pacients amb hipertensió arterial respecte al seguiment habitual d'aquestspacients en consultes mèdiques.Mètode: S'estudiaran a 34 adults hipertensos mitjançant un assaig clínic aleatoritzat en dos grupsde 17 pacients hipertensos. El grup experimental serà objecte d'unes intervencions educativessobre la hipertensió i la repercussió dels estils de vida pel control d'aquesta patologia per partd'infermeria, a més a més, d'un control rutinari mèdic. Mentre que el grup control solamentassistirà als controls rutinaris mèdics sobre la hipertensió i no rebrà intervencions infermeres. Enl'avaluació de les dades es tindran en compte les variables de la mesura de la tensió arterial, ladieta, l'exercici físic i el seguiment del tractament, a més de diferents variablessociodemogràfiques com són l'edat, el gènere i el nivell socioeconòmic. Les dades s'analitzaranmitjançant Chi Cuadrat per a les variables qualitatives, la Correlació de Pearson i la de Spearmanper a les variables quantitatives i, finalment, la T de Student per a la comparació de la mitja de lesdues mostres independents.Conclusió: Amb l'assaig clínic es pretés demostrar que les intervencions d’infermeria en consultesmilloren l'autocontrol dels pacients amb hipertensió arterial, és a dir, són eficaces.

Long-term treatment of hypertension in man by an orally active angiotensin-converting enzyme inhibitor.

1. Captopril or SQ 14 225, administered orally twice a day, reduced the blood pressure of hypertensive patients whatever their clinical diagnosis and even when their plasma renin activity was 'normal' or low. 2. Long-term administration of captopril, either alone or together with diuretics, provides a powerful new tool with which to treat ambulatory hypertensive patients. 3. The renin system may play an important role in maintaining blood pressure in a majority of hypertensive patients.

Transcranial Doppler Pulsatility Index: What it is and What it Isn't.

BACKGROUND: Transcranial Doppler (TCD) pulsatility index (PI) has traditionally been interpreted as a descriptor of distal cerebrovascular resistance (CVR). We sought to evaluate the relationship between PI and CVR in situations, where CVR increases (mild hypocapnia) and decreases (plateau waves of intracranial pressure-ICP). METHODS: Recordings from patients with head-injury undergoing monitoring of arterial blood pressure (ABP), ICP, cerebral perfusion pressure (CPP), and TCD assessed cerebral blood flow velocities (FV) were analyzed. The Gosling pulsatility index (PI) was compared between baseline and ICP plateau waves (n = 20 patients) or short term (30-60 min) hypocapnia (n = 31). In addition, a modeling study was conducted with the "spectral" PI (calculated using fundamental harmonic of FV) resulting in a theoretical formula expressing the dependence of PI on balance of cerebrovascular impedances. RESULTS: PI increased significantly (p < 0.001) while CVR decreased (p < 0.001) during plateau waves. During hypocapnia PI and CVR increased (p < 0.001). The modeling formula explained more than 65% of the variability of Gosling PI and 90% of the variability of the "spectral" PI (R = 0.81 and R = 0.95, respectively). CONCLUSION: TCD pulsatility index can be easily and quickly assessed but is usually misinterpreted as a descriptor of CVR. The mathematical model presents a complex relationship between PI and multiple haemodynamic variables.

Effects of a nonpressor dose of neuropeptide Y on cardiac output, regional blood flow distribution and plasma renin, vasopressin and catecholamine levels.

Neuropeptide Y (NPY) is a peptide with vasoconstrictor properties known to be present in the central nervous system as well as in sympathetic nerve endings and the adrenal medulla. The purposes of this study were to investigate in normotensive conscious rats the effects of nonpressor doses of NPY on cardiac output and regional blood flow distribution (using radiolabeled microspheres) as well as on plasma renin activity, plasma catecholamine and vasopressin levels. NPY (0.1 microgram/min) infused i.v. for 30 min modified neither blood pressure nor heart rate. Cardiac index was at comparable levels in NPY- as in vehicle-treated rats (17.7 +/- 1.6, n = 8, vs. 21.3 +/- 0.9 ml/min/100 g, n = 8, mean +/- S.E.M.). There was no significant difference in regional blood flow distribution between the two groups of rats, except for the large intestine (0.42 +/- 0.06 vs. 0.71 +/- 0.1 ml/min/g in NPY- and vehicle-treated rats, respectively, P less than .05). Basal plasma renin activity and catecholamine levels were not modified by NPY whereas plasma vasopressin levels were lower (P less than .05) in rats given NPY (0.76 +/- 0.3 pg/ml, n = 8) than in those having received the vehicle (2.2 +/- 0.4 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure.

Numerous genetic loci have been associated with systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N = 74,064) and follow-up studies (N = 48,607), we identified at genome-wide significance (P = 2.7 × 10(-8) to P = 2.3 × 10(-13)) four new PP loci (at 4q12 near CHIC2, 7q22.3 near PIK3CG, 8q24.12 in NOV and 11q24.3 near ADAMTS8), two new MAP loci (3p21.31 in MAP4 and 10q25.3 near ADRB1) and one locus associated with both of these traits (2q24.3 near FIGN) that has also recently been associated with SBP in east Asians. For three of the new PP loci, the estimated effect for SBP was opposite of that for DBP, in contrast to the majority of common SBP- and DBP-associated variants, which show concordant effects on both traits. These findings suggest new genetic pathways underlying blood pressure variation, some of which may differentially influence SBP and DBP.

Medical treatment of hypertension in Switzerland. The 2009 Swiss Hypertension Survey (SWISSHYPE).

OBJECTIVES: Despite a broad and efficient pharmacological antihypertensive armamentarium, blood pressure (BP) control is suboptimal and heterogeneous throughout Europe. Recent representative data from Switzerland are limited. The goal of the present survey was therefore to assess the actual control rate of high BP in Switzerland in accordance with current guidelines. The influence of risk factors, target organ damage and medication on BP levels and control was also evaluated.METHODS : A cross-sectional visit-based survey of ambulatory hypertensive patients was performed in 2009 in Switzerland. 281 randomly selected physicians provided data on 5 consecutive hypertensive patients attending their practices for BP follow-up. Data were anonymously collected on demographics, comorbidities and current medication, and BP was recorded. Subsequent modification of pharmacological antihypertensive therapy was assessed.RESULTS : Data from 1376 patients were available. Mean age was 65 +/- 12 years, 53.9% were male subjects. 26.4% had complicated hypertension. Overall, BP control (<140/90 mm Hg for uncomplicated and <130/80 mm Hg for complicated hypertension) was achieved in 48.9%. Compared to patients with complicated hypertension, BP control was better in patients with uncomplicated hypertension (59.4% vs. 19.2%, p < 0.001). As a monotherapy the most prescribed drug class were angiotensin receptor blockers (ARB, 41%), followed by angiotensin converting enzyme (ACE) inhibitors (21.5%), betablockers (20.8%) and calcium channel blockers (CCB, 10.8%). The most prescribed drug combinations were ARB + diuretic (30.1%) and ACE inhibitors + diuretic (15.3%). 46% were receiving a fixed drug combination. In only 32.7% of patients with uncontrolled hypertension was a change in drug therapy made.CONCLUSION : This representative survey on treated adult hypertensive patients shows that, compared to earlier reports, the control rate of hypertension has improved in Switzerland for uncomplicated but not for complicated, particularly diabetes-associated hypertension. ARBs and ACE inhibitors are the most prescribed antihypertensive drugs for monotherapy, whereas diuretics and ARBs were the most used for combination therapy.

Low utilization of health care services following screening for hypertension in Dar es Salaam (Tanzania): a prospective population-based study.

BACKGROUND: Drug therapy in high-risk individuals has been advocated as an important strategy to reduce cardiovascular disease in low income countries. We determined, in a low-income urban population, the proportion of persons who utilized health services after having been diagnosed as hypertensive and advised to seek health care for further hypertension management. METHODS: A population-based survey of 9254 persons aged 25-64 years was conducted in Dar es Salaam. Among the 540 persons with high blood pressure (defined here as BP >or= 160/95 mmHg) at the initial contact, 253 (47%) had high BP on a 4th visit 45 days later. Among them, 208 were untreated and advised to attend health care in a health center of their choice for further management of their hypertension. One year later, 161 were seen again and asked about their use of health services during the interval. RESULTS: Among the 161 hypertensive persons advised to seek health care, 34% reported to have attended a formal health care provider during the 12-month interval (63% public facility; 30% private; 7% both). Antihypertensive treatment was taken by 34% at some point of time (suggesting poor uptake of health services) and 3% at the end of the 12-month follow-up (suggesting poor long-term compliance). Health services utilization tended to be associated with older age, previous history of high BP, being overweight and non-smoking, but not with education or wealth. Lack of symptoms and cost of treatment were the reasons reported most often for not attending health care. CONCLUSION: Low utilization of health services after hypertension screening suggests a small impact of a patient-centered screen-and-treat strategy in this low-income population. These findings emphasize the need to identify and address barriers to health care utilization for non-communicable diseases in this setting and, indirectly, the importance of public health measures for primary prevention of these diseases.