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PubMed1985

Artificial sphincter pressure versus detrusor leakage pressure.

Increasing urethral occlusion pressures were created with an artificial sphincter in fresh bladder-urethra specimens of adult pigs. Detrusor leakage pressures remained about 25 per cent below the associated sphincter cuff pressures. The same relation was found when, during abrupt variations of cuff pressure, the detrusor leakage pressures were measured with antegrade urethral perfusion pressure measurement through a new sleeve catheter. Side-hole perfusion pressure measurements showed 100 per cent transmission of abrupt variations of cuff pressures to the inner urethral wall. No rotational differences could be detected. From the results it has been concluded that a probable pressure loss of about 25 per cent must be taken into account when converting artificial sphincter pressures into bladder pressures at which leakage will occur.

Adult↗

PubMed1994

Pressure sores and pressure-decreasing mattresses: controlled clinical trial.

Pressure sores are a problem, especially in elderly patients. Our study was designed to determine the effectiveness in pressure-sore prevention of a new interface-pressure decreasing mattress. In a prospective randomised controlled clinical trial we tested the Comfortex DeCube mattress (Comfortex, Winona, USA) against our standard hospital mattress in 44 patients with femoral-neck fracture and concomitant high pressure-sore risk score. In addition both groups were treated according to the Dutch consensus protocol for the prevention of pressure sores. On admission and 1 and 2 weeks after admission, pressure sores were graded. The two groups were similar in patient characteristics and pressure-sore risk factors. At 1 week, 25% of the patients nursed on the DeCube mattress and 64% of the patients nursed on the standard mattress had clinically relevant pressure sores (grade 2 or more). At 2 weeks the figures were 24% and 68%, respectively. The maximum score over the several body regions of the pressure-sore grading, measured on a 5-point sale, was significantly different in favour of the DeCube mattress at 1 week (p = 0.0043) and 2 weeks (p = 0.0067) postoperatively. We show that the occurrence of pressure sores and their severity can be significantly reduced when patients at risk are nursed on an interface-pressure decreasing mattress.

Aged↗

PubMed1999

Using a case-mix-adjusted pressure sore incidence study in a surgical directorate to improve patient outcomes in pressure ulcer prevention.

The Glasgow Acute Clinical Audit Sub-Committee on Pressure Sores has previously carried out studies of incidence of pressure ulcers in the medical directorates and case-mix-adjusted the figures for length of hospital stay and risk assessment score. Case-mix classification is 'classification of people or treatment placed into groups using characteristics associated with condition, treatment or outcome that can be used to predict need, resource, use of outcomes'. In this instance, crude pressure ulcer incidence figures may be adjusted for length of hospital stay and pressure sore risk assessment score, and stratified into groups, which allows like to be compared with like. The value in case-mix-adjusted figures lies in repeating the exercise, thus determining the trend for individual areas and assessing whether improvement in the quality of care is being achieved. This is more positive than creation of 'league tables' comparing simultaneous studies in a number of areas. The figures showed that there was no statistically significant difference between surgical directorates in trusts with regard to risk assessment scores and length of hospital stay. Gathering data on the incidence of pressure ulcer development allows us to identify where new sores are occurring, but does not critically analyse the nursing intervention taken in individual cases, which identifies preventive strategies. The Glasgow group's primary aim was to gather data on case-mix-adjusted incidence of pressure damage; the secondary objectives were to scrutinize the data to gather more general information on intrinsic and extrinsic factors which may predispose to pressure ulcer development. The study was carried out in the surgical directorate. Findings showed that incidence was low (1.1%), with the majority of sores being superficial. There was a correlation between pressure ulcer development and incontinence, evidence of under-utilization of moving and handling aids for prevention of pressure ulcers, and a need for greater collaboration between nursing staff and dietitians. All patients had access to pressure-reducing surfaces, with cut-foam pressure-reducing mattresses with vapour-permeable covers on all beds. Dynamic systems were available if the primary nurse identified a need for them.

Adolescent↗

PubMed2002

Empirical estimates of mean aortic pressure: advantages, drawbacks and implications for pressure redundancy.

Mean arterial pressure (MAP) is estimated at the brachial artery level by adding a fraction of pulse pressure (form factor; =0.33) to diastolic pressure. We tested the hypothesis that a fixed form factor can also be used at the aortic root level. We recorded systolic aortic pressure (SAP) and diastolic aortic pressure (DAP), and we calculated aortic pulse pressure (PP) and the time-averaged MAP in the aorta of resting adults (n=73; age 43+/-14 years). Wave reflection was quantified using the augmentation index. The aortic form factor (range 0.35-0.53) decreased with age, MAP, PP and augmentation index (each P<0.001). The mean form factor value (0.45) gave a reasonable estimation of MAP (MAP=DAP+0.45PP; bias=0+/-2 mmHg), and the bias increased with MAP (P<0.001). An alternative formula (MAP=DAP+PP/3+5 mmHg) gave a more precise estimation (bias=0+/-1 mmHg), and the bias was not related to MAP. This latter formula was consistent with the previously reported mean pulse wave amplification of 15 mmHg, and with unchanged MAP and diastolic pressure from aorta to periphery. Multiple linear regression showed that 99% of the variability of MAP was explained by the combined influence of DAP and SAP, thus confirming major pressure redundancy. Results were obtained irrespective of whether the marked differences in heart period and extent of wave reflection between subjects were taken into account. In conclusion, the aortic form factor was strongly influenced by age, aortic pressure and wave reflection. An empirical formula (MAP=DAP+PP/3+5 mmHg) that is consistent with mechanical principles in the arterial system gave a more precise estimate of MAP in the aorta of resting humans. Only two distinct pressure-powered functions were carried out in the (SAP, DAP, MAP, PP) four-pressure set.

Adult↗

PubMed2001

Effects of pressure on the activity and spectroscopic properties of carboxyl proteinases. Apparent correlation of pepstatin-insensitivity and pressure response.

The pressure dependence of the activity and spectroscopic properties of four carboxyl proteinases were investigated. Two were pepstatin-sensitive carboxyl proteinases (porcine pepsin and proteinase A from baker's yeast) and two were pepstatin-insensitive carboxyl proteinases (from Pseudomonas sp. 101 (pseudomonapepsin; PCP) and Xanthomonas sp. T-22 (xanthomonapepsin; XCP)). The specificity constant [k(cat)/K(m(app))] of PCP and XCP for a synthetic peptide substrate showed only a slight decrease with increasing pressure, whereas pepsin and proteinase A showed substantial disactivation at higher pressures. The calculated apparent activation volume (Delta V((k(cat)/(K(m)) was about 1, 3, 13, and 14 mL.mol(-1) for PCP, XCP, pepsin, and proteinase A, respectively. The hydrolysis of acid-denatured myoglobin by the four carboxyl proteinases was only slightly affected by high pressure (except for proteinase A at 400 MPa), in contrast to the results for the peptide hydrolysis. In fact, PCP, XCP, and proteinase A actually showed slightly higher degradations of acid-denatured myoglobin at higher pressures. The residual activities of these enzymes after the incubation at high pressures implied a pressure-induced stabilization towards autolysis. The changes in the fourth derivative near-UV absorbance spectrum of the four enzymes in aqueous solution were measured at various pressures from 0.1 to 400 MPa. Upon an increase in pressure, the peaks from PCP and XCP red-shifted slightly, whereas pepsin and proteinase A blue-shifted substantially, thus indicating a more polar environment. The intrinsic fluorescence also decreased upon increasing pressure. However, the change for XCP was rather small, but the change for the other three was very large. The changes in the peak wavelength for pepsin and proteinase A were characteristic, and also indicated a more polar environment under high pressure. An analysis by the center of spectra mass (CSM) gave the Delta G and Delta V of transition as 9.8 kJ x mol(-1) and -24 mL x mol(-1) (pepsin) and 11.7 kJ x mol(-1) and -43 mL x mol(-1) (proteinase A), respectively, by assuming a simple two-state transition. The circular dichroism (CD) showed relatively small changes after 1-h incubations at 400 MPa, indicating that the secondary structures were largely maintained.

Animals↗

PubMed2001

[Doppler ultrasound diagnosis of increased intracranial pressure by comparison of 2 blood flow velocities in the extra- and intracranial segment of the internal carotid artery. 2: Findings in children with increased intracranial pressure].

AIM: We investigated the correlation between intracranial pressure and flow parameters by simultaneous Doppler sonographic flow measurements in the internal carotid arteries and estimation of the intracranial pressure over the anterior fontanelle. METHOD: 12 infants (7 boys and 5 girls) with increased intracranial pressure were investigated. The corrected gestational age at investigation was 42 +/- 14 weeks, the weight was 3080 +/- 2540 g. Intracranial pressure was measured by applanation tonometry over the anterior fontanelle. The infants were subdivided into two groups: Group 1 (9 infants) with slightly increased intracranial pressure (16.9 +/- 3.3 cm H2O) and group 2 (3 infants) with moderately increased intracranial pressure (21.6 +/- 3.3 cm H2O). In all infants Doppler sonographic flow measurements within the intra- and extracranial segments of the internal carotid arteries were performed. From the flow profile, the peak systolic flow velocity Vs, the enddiastolic flow velocity Ved as well as the time average flow velocity TAV and the resistance index RI were measured. From the flow velocities, the I/E-ratio was calculated. The measured variables were compared with the values of matched pairs of a healthy control group of similar age and weight. RESULTS: Group 1 with slightly increased intracranial pressure displayed no significant difference of the RI within intracranial and extracranial sections of the internal carotid artery and the control group. The flow velocities, however, showed a significant increase within the intracranial segment of the internal carotid artery in comparison with the extracranial part of the internal carotid artery as well as the healthy control group. I/E-ratio for Vs increased significantly to 1.29 +/- 0.19, for Ved to 1.24 +/- 0.27 and for TAV to 1.08 +/- 0.27. Group 2 with moderately increased intracranial pressure displayed a significant increase of RI within the intracranial section of the internal carotid artery to 0.89 +/- 0.08 in comparison to the extracranial section with 0.79 +/- 0.07 and to the healthy control group with 0.75 +/- 0.07. All flow velocities decreased significantly within the intracranial section of the internal carotid artery in comparison to the extracranial part of the internal carotid artery and the healthy control group. The I/E-ratio was significantly reduced in group 2 with 0.76 +/- 0.11 for Vs, 0.38 +/- 0.21 for Ved, and 0.58 +/- 0.16 for TAV. CONCLUSION: Flow measurements in extra- and intracranial sections of the internal carotid arteries are an accurate method for semiquantitative estimation of increased intracranial pressure. This method is superior to the measurement of the RI. Slightly increased intracranial pressures below 20 cm H2O cause an increase of the I/E-ratio above 1, whereas the RI does not change. Moderately increase of the intracranial pressure above 20 cm H2O lowers the I/E-ratio significantly below normal values of 0.8, whereas the RI increases.

Blood Flow Velocity↗

PubMed2003

[Lowering of blood pressure, blood pressure amplitude and heart rate by treatment with valsartan or valsartan/hydrochlorothiazide. Results of an open observation study of 11,447 hypertensives].

OBJECTIVE: This trial investigated the decrease of blood pressure, safety and tolerability of valsartan, an angiotensin-receptor blocker, alone or combined with the diuretic hydrochlorothiazide. In addition, the effect on pulse pressure, heart rate and mean blood pressure were recorded as independent markers of cardiovascular risk. PATIENTS AND METHODS: 12278 hypertensive patients were treated for 12 weeks with valsartan alone or combined with hydrochlorothiazide in a multi-centre open trial. Previously established antihypertensive treatment was continued. Systolic and diastolic pressure, pulse pressure and resting heart rate were recorded at the start of the trial and at 1, 4 and 12 weeks thereafter. RESULTS: Data on 11447 were complete enough to be evaluated (54% males, 46% females; mean age 60.8 years). 44% of the patients were at the same time receiving other antihypertensive drugs at the start of the trial, but the numbers so treated decreased during the trial period. Systolic pressure was reduced by 27.8 mmHg. diastolic pressure by 14.7 mmHg, with a calculated reduction of pulse pressure from 71.5 to 58.7 mmHg. Heart rate was reduced by 3.4 beats. The treatment had to be stopped prematurely in 2.3% of patients because of side effects. There were no severe or life-threatening side effects. CONCLUSION: Treatment with valsartan alone or combined with hydrochlorothiazide provides effective blood pressure reduction and is well tolerated. This trial suggests that, in addition to the fall in blood pressure, the independent risk factors of cardiovascular disease, pulse pressure and resting heart rate, were also reduced during administration of valsartan.

Angiotensin Receptor Antagonists↗

PubMed2004

The second peak of the radial artery pressure wave represents aortic systolic pressure in hypertensive and elderly patients.

BACKGROUND: Simultaneous measurement of ascending aorta and radial artery pressure shows that mean and diastolic pressures (DP) are in close agreement in normotensive adults, while systolic pressures (SP) are not. However, in the aortic pressure wave, a second systolic peak appears with increasing age and increases to represent the SP by age 32 yr, while in the radial artery, a second systolic deflection appears by age 40 yr. We suggest that the second radial systolic wave, sometimes seen during radial arterial pressure monitoring in older hypertensives, represents the aortic SP. We set out to evaluate whether the aortic and radial second systolic peaks agree, and since doubts exist about the agreement between aortic and radial DP in elderly hypertensive patients, we also assessed that relationship. METHODS: We compared simultaneously recorded radial and aortic pressures from 21 anaesthetized adult patients using identical fluid-filled pressure measuring systems. CONCLUSIONS: The second radial pressure peak agreed with that in the aorta within a mean of 0.6 (SD 1.5) mm Hg. The difference between DP in the aorta and radial artery was -1.4 (2) mm Hg. The radial-aortic SP and pulse pressure differences were 5.9 (7.6) and 7.3 (7.6) mm Hg, respectively. These results confirm that when the radial artery pressure wave shows a first and second, or only a second systolic shoulder/peak (on the right side of the pressure wave), the second represents the maximal ascending aortic SP, and that the radial and aortic DP are equivalent, even in older hypertensive patients.

Adult↗

PubMed1986

Hysteresis of left ventricular end ejection pressure-dimension relations after acute pressure loading in the intact canine heart.

The left ventricular end systolic pressure-volume relation of the isolated canine heart is linear and independent of the loading conditions. The effects of acute pressure loading on the left ventricular end ejection pressure-length relations were studied in the intact canine heart. The lengths of two wall segments of the left ventricle parallel to the minor axis were measured with pairs of miniature piezoelectric crystals. At two levels of filling pressure, with and without control of heart rate, acute increases in left ventricular afterload were produced for six successive beats by occluding the thoracic aorta. After abrupt release of this occlusion, at left ventricular end diastolic pressure less than 10 mmHg, end ejection lengths were longer than before the occlusion for both segments despite the same or lower end ejection pressures. When heart rate was not controlled the mean(SD) difference in end ejection length was 0.46(0.21) mm (n = 100). When heart rate was controlled by atrial pacing after autonomic blockade the difference was 0.37(0.11) mm (n = 80). In contrast, at left ventricular end diastolic pressure greater than 10 mmHg there was no significant difference between end ejection lengths before and after release of the aortic occlusion. Gradual release of the aortic occlusion over 4-5 beats produced clockwise hysteresis of the left ventricular end ejection pressure-length relation when left ventricular end diastolic pressure was less than 10 mmHg. No hysteresis occurred when left ventricular end diastolic pressure was greater than 10 mmHg. Hysteresis of the end systolic pressure-dimension relation was also seen when major and minor axis dimensions of the left ventricular were measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

31P magnetic resonance spectroscopy of pressure overload hypertrophy in rats: effect of reduced perfusion pressure.

STUDY OBJECTIVE - The purpose of the study was to confirm the presence of abnormalities in the coronary vessels of hypertensive hearts, and to examine the effects of reduced coronary perfusion pressure. DESIGN - Rats were made hypertensive by aortic banding, after which coronary flow and myocardial energy metabolites were studied in isolated hearts at physiological (140 cm H2O) and reduced (80 cm H2O) coronary perfusion pressures and compared with normotensive controls. SUBJECTS - Wistar-Kyoto rats between 250 and 300 g were used. Left ventricular hypertrophy was generated by aortic banding in 29 rats; 8 were studied one week after banding, and 21 three weeks after banding. There were 45 controls. MEASUREMENTS and RESULTS - Energy metabolites were assessed using 31P magnetic resonance spectroscopy, standardised by high performance liquid chromatography of rapidly freeze clamped tissue. Left ventricular wall thickness was determined using two dimensional echocardiography. Coronary flow (normalised for heart weight) was reduced significantly after one and three weeks of left ventricular hypertrophy, and at either physiological or below physiological pressures. Hearts from aortic banded animals developed higher intraventricular pressure with reduced oxygen consumption when perfused at a physiological pressure, indicating increased thermodynamic efficiency. When perfused at reduced pressure, the developed pressure declined significantly in both the one week and the three week banded groups compared to normal hearts. The phosphorylation potential and intracellular pH (pHi) were not significantly lower after one week and three weeks of left ventricular hypertrophy when perfused at physiological pressure. When perfused at reduced pressure, phosphorylation potential declined significantly in both groups of hypertrophied hearts, whereas pHi declined significantly only in the three week hypertrophy group. CONCLUSIONS - There is improved thermodynamic efficiency of the hypertrophied myocardium when perfused at a physiological pressure, but when perfused at a reduced pressure, ventricular function, phosphorylation potential and pHi decline in rat hearts after three weeks of aortic constriction, indicating an impairment of coronary reserve.

Animals↗

PubMed1991

Postural change in blood pressure associated with age and systolic blood pressure. The National Health and Nutrition Examination Survey II.

The prevalence of postural change in blood pressure and its association with age and systolic blood pressure were examined in data from 8,574 White nondiabetic persons aged 25-74 who participated in the second National Health and Nutrition Examination Survey (1976-1980). Postural change in blood pressure was defined as a drop of 20 mm Hg or more on change from supine to seated position. In subjects on no antihypertensive medications (n = 7,316), the prevalence of postural change in blood pressure increased with older age and with higher blood pressure levels, regardless of age. However, systolic blood pressure levels also increased with age. In logistic regression models, level of supine systolic blood pressure was strongly related to postural change in blood pressure (Relative odds (RO) = 1.59, 95% confidence interval (CI) = 1.49, 1.70 for a 10 mm Hg increase in systolic blood pressure) whereas age was not related to postural change in blood pressure (RO for age = 1.07, Cl = .89, 1.19 for a 10-year increase in age). Results were similar for those medicated for hypertension. All results were unchanged by addition of health status indicators, including reports of hospitalization and number of medical conditions, to the model. These data suggest that the age-related increase in the prevalence of postural hypotension previously reported may be partially explained by age-associated increases in systolic blood pressure.

Adult↗

PubMed2001

Seasonal variation in xylem pressure of walnut trees: root and stem pressures.

Measurements of air and soil temperatures and xylem pressure were made on 17-year-old orchard trees and on 5-year-old potted trees of walnut (Juglans regia L.). Cooling chambers were used to determine the relationships between temperature and sugar concentration ([glucose] + [fructose] + [sucrose], GFS) and seasonal changes in xylem pressure development. Pressure transducers were attached to twigs of intact plants, root stumps and excised shoots while the potted trees were subjected to various temperature regimes in autumn, winter and spring. Osmolarity and GFS of the xylem sap (apoplast) were measured before and after cooling or warming treatments. In autumn and spring, xylem pressures of up to 160 kPa were closely correlated with soil temperature but were not correlated with GFS in xylem sap. High root pressures were associated with uptake of mineral nutrients from soil, especially nitrate. In autumn and spring, xylem pressures were detected in root stumps as well as in intact plants, but not in excised stems. In contrast, in winter, 83% of the xylem sap osmolarity in both excised stems and intact plants could be accounted for by GFS, and both GFS and osmolarity were inversely proportional to temperature. Plants kept at 1.5 degrees C developed positive xylem pressures up to 35 kPa, xylem sap osmolarities up to 260 mosmol l(-1) and GFS concentrations up to 70 g l(-1). Autumn and spring xylem pressures, which appeared to be of root origin, were about 55% of the theoretical pressures predicted by osmolarity of the xylem sap. In contrast, winter pressures appeared to be of stem origin and were only 7% of the theoretical pressures, perhaps because of a lower stem water content during winter.

Juglandaceae↗

PubMed1999

Pharyngeal mucosal pressures, airway sealing pressures, and fiberoptic position with the intubating versus the standard laryngeal mask airway.

BACKGROUND: The tube of the intubating laryngeal mask (ILM) is more rigid than the standard laryngeal mask airway (LMA), and the authors have tested the hypothesis that pharyngeal mucosal pressures, airway sealing pressures, and fiberoptic position are different when the two devices are compared. METHODS: Twenty anesthetized, paralyzed adults were randomly allocated to receive either the LMA or ILM for airway management. Microchip sensors were attached to the size 5 LMA or ILM at locations corresponding to the pyriform fossa, hypopharynx, base of tongue, posterior pharynx, and distal and proximal oropharynx. Mucosal pressures, airway sealing pressures, and fiberoptic positioning were recorded during inflation of the cuff from 0 to 40 ml in 10-ml increments. RESULTS: Airway sealing pressures were higher for the ILM (30 vs. 23 cm H2O), but epiglottic downfolding was more common (56% vs. 26%). Pharyngeal mucosal pressures were much higher for the ILM at five of six locations. Mean mucosal pressures in the distal oropharynx for the ILM were always greater than 157 cm H2O, regardless of cuff volume. There was no correlation between mucosal pressures and airway sealing pressures at any location for the LMA, but there was a correlation at three of six locations for the ILM. CONCLUSIONS: The ILM provides a more effective seal than the LMA, but pharyngeal mucosal pressures are higher and always exceed capillary perfusion pressure. The ILM is unsuitable for use as a routine airway and should be removed after its use as an airway intubator.

Adult↗

PubMed1996

Low measured auto-positive end-expiratory pressure during mechanical ventilation of patients with severe asthma: hidden auto-positive end-expiratory pressure.

OBJECTIVE: To describe the occurrence of low measured auto-end-expiratory pressure (auto-PEEP) during mechanical ventilation of patients severe asthma. DESIGN: Observational clinical study. SETTING: Medical intensive care unit of a university-affiliated county hospital. PATIENTS: Four mechanically ventilated patients with severe asthma who had low measured auto-PEEP despite marked increase in both peak and plateau airway pressures. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Peak pressure, plateau pressure, and auto-PEEP were measured at an early time point, when airflow obstruction was most severe, and again at a later time after clinical improvement. Auto-PEEP was measured by the method of end-expiratory airway occlusion. From the early to the late point, there was a marked decrease in peak pressure (76 +/- 7 to 53 +/- 6 cm H2O; p<.001) and in plateau pressure (28 +/- 2 to 18 +/- 3 cm H2O; p<.001), but only minimal change in auto-PEEP (5 +/- 3 to 4 +/- 3 cm H2O). The difference between plateau pressure and auto-PEEP decreased between the early and late time points (23 +/- 1 to 14 +/- 1 cm H2O; p<.01), even though tidal volume was larger at the late time point. In three patients, low auto-PEEP and a large difference between plateau pressure and auto-PEEP was only seen after expiratory time was prolonged. In these three patients, prolongation of expiratory time resulted in a large decrease in measured auto-PEEP (14 +/- 4 to 5 +/- 4 cm H2O), but a much smaller change in plateau pressure (31 +/- 3 to 29 +/- 3 cm H2O). CONCLUSIONS: We conclude that measured auto-PEEP may underestimate end-expiratory alveolar pressure in severe asthma, and that marked pulmonary hyperinflation may be present despite low measured auto-PEEP, especially at low respiratory rates. This phenomenon may be due to widespread airway closure that prevents accurate assessment of alveolar pressure at end-expiration.

Acute Disease↗

PubMed2003

Fasting blood glucose is independently associated with resting and exercise blood pressures and development of elevated blood pressure.

OBJECTIVE: To assess whether fasting blood glucose is independently related to blood pressure at rest and during exercise, and to development of elevated blood pressure. DESIGN: Cross-sectional and prospective cohort study of 2014 apparently healthy middle-aged men. METHODS: The baseline survey included carefully standardized blood pressure measurements at rest and during exercise testing, an intravenous glucose tolerance test and a panel of fasting blood tests, including fasting blood glucose. Results from 7-years follow-up provided data on development of elevated blood pressure. RESULTS: Strong associations were found between quartiles of fasting blood glucose and baseline resting and/or exercise levels of blood pressure, and also development of elevated blood pressure over 7 years. Physical fitness, calculated from an exercise test, had a strong modulating effect on blood pressure at all levels of fasting blood glucose. In multivariate models - after adjusting for intravenous glucose tolerance, physical fitness, age, body mass index, triglycerides and cholesterol - fasting blood glucose was strongly associated with blood pressure at rest (coefficient = 2.83, P = 0.0004) and during exercise (coefficient = 6.57, P < 0.0001), and further to development of treated hypertension and/or elevated blood pressure [odds ratio (OR), 1.17; 95% confidence interval (CI), 1.05-1.31]. CONCLUSION: In healthy non-diabetic and non-hypertensive men, strong associations were found between fasting blood glucose and blood pressure at rest and during exercise and to development of elevated blood pressure after 7-years follow-up. Fasting glucose metabolism deserves scrutiny when studying the pathogenesis of hypertension.

Adult↗

PubMed2004

Reconstruction of brachial pressure from finger arterial pressure during orthostasis.

INTRODUCTION: In patients with recurrent syncope, monitoring of intra-arterial pressure during orthostatic stress testing is recommended because of the potentially sudden and rapid development of hypotension. Replacing brachial arterial pressure (BAP) by the non-invasively obtained finger arterial pressure (FinAP) has advantages because catheterization in itself may provoke a syncope. OBJECTIVE: To investigate whether reconstruction of the brachial pressure curve (ReBAP) from FinAP can account for systolic and diastolic offset in the recorded pressure on the transition from a supine to an upright position and during maintained postural stress. METHODS: In nine healthy young subjects BAP and FinAP were recorded in the supine position, during 8 min of standing and during 20 min of 70degrees passive head-up tilt (HUT70) whereafter three of the subjects fainted within 20 min of HUT. The FinAP signal was modeled off-line into a reconstructed brachial pressure curve. RESULTS: For FinAP but not for ReBAP, systolic (P < 0.05) and diastolic (P < 0.001) bias increased in the transition from the supine to the HUT position. Bias for the systolic pressure in the supine position and after 7.5 and 20 min of HUT were 2, 7 and 11 mmHg for FinAP but only 0, -2 and 1 mmHg for ReBAP (P < 0.05 for HUT). For the diastolic pressure these values were -2, 5 and 8 mmHg for FinAP and 4, 5 and 6 for ReBAP (P < 0.01 for supine). CONCLUSIONS: Brachial pressure reconstruction from the finger arterial pressure waveform accounts for the bias from the supine to the upright position, eliminates the bias for the systolic but not for diastolic finger pressure and reduces the trend in diastolic bias with increased tilt duration.

Adult↗

PubMed2005

Effects of inhaled nitrous oxide 50% on estimated cerebral perfusion pressure and zero flow pressure in healthy volunteers.

The role of vascular tone in determining cerebral perfusion pressure is increasingly being appreciated. It has been suggested that zero flow pressure, the arterial pressure at which blood flow ceases, represents the effective downstream pressure of the cerebral circulation. Nitrous oxide is a cerebral vasodilator and may therefore decrease zero flow pressure and increase cerebral perfusion pressure. However, these effects may be opposed by the increase in intracranial blood volume produced by cerebral vasodilation. We studied eight healthy volunteers at normocapnia and studied the effects of the inhalation of nitrous oxide 50% on estimated cerebral perfusion pressure and zero flow pressure using transcranial Doppler ultrasonography. We found that nitrous oxide 50% significantly increased estimated cerebral perfusion pressure (p = 0.03), whilst decreasing zero flow pressure (p = 0.01). These results suggest that the vasomotor effects of nitrous oxide predominate in determining the effective downstream pressure of the cerebral circulation in healthy individuals.

Adolescent↗

PubMed1990

Extravascular absorption of irrigating fluid during TURP. The role of transmural bladder pressure as the driving pressure gradient.

The critical intravesical pressure range for extravascular absorption of irrigating fluid (EVA) during transurethral resection of the prostate (TURP) is determined by the pressure in the perivesical tissue. This means that the transmural bladder pressure (detrusor pressure), calculated by deducting perivesical pressure from intravesical pressure during cystometry, is the pressure gradient behind EVA. The transmural pressure in 6 patients undergoing TURP has been studied both before and during epidural anaesthesia, using both conventional medium-fast fill cystometry and "free-flow" cystometry through the resectoscope. Epidural block does not influence the transmural pressure response on filling the bladder and neither does the type of infusion. A positive transmural pressure, and thereby a pressure gradient for EVA, exists already during the very early phase of bladder filling. Incomplete perforation of the prostatic capsule and clotting, as well as the accumulation of irrigating fluid in the perivesical tissue, probably moderate the rate of absorption.

Absorption↗