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PubMed1992

Intermittent mandatory ventilation with continuous negative pressure compared with positive end-expiratory pressure for neonatal hypoxemia.

The use of continuous negative pressure was prospectively studied in 30 preterm and term hypoxemic (PaO2 < 45 mm Hg) neonates. Infants were randomly assigned to either positive end-expiratory pressure or continuous negative pressure if conventional positive pressure ventilation failed to improve oxygenation. Crossover to the alternative therapy occurred if infants remained hypoxemic after 2 hours. In the continuous negative pressure group, 2 (13%) crossed over to positive end-expiratory pressure, whereas 11 (73%) in the positive end-expiratory pressure group crossed over to continuous negative pressure (p = 0.003). Only five patients remained in the positive end-expiratory pressure group 36 hours after randomization. Compared with positive end-expiratory pressure, continuous negative pressure significantly increased PaO2 (69 +/- 17 mm Hg vs 36 +/- 8 mm Hg) and arterial-alveolar ratio (0.098 +/- 0.070 vs 0.057 +/- 0.014) 30 minutes after randomization and after crossover to continuous negative pressure (60 +/- 12 mm Hg vs 37 +/- 5 mm Hg, and 0.154 +/- 0.096 vs 0.058 +/- 0.009). The use of continuous negative pressure did not increase morbidity. Overall survival was 83.3%. Only three infants were referred to extracorporeal membrane oxygenation. Rescue therapy with continuous negative pressure is effective in infants with refractory hypoxemia and may be considered before referral for extracorporeal membrane oxygenation.

Female↗
PubMed1991

Dynamic urethral pressure profilometry pressure transmission ratio: what do the numbers really mean?

Sixty-three women with genuine stress urinary incontinence were evaluated urodynamically both before and after modified Burch colposuspension to determine the association between pressure transmission ratio and leakage of urine during dynamic urethral pressure profile and the effect of surgery on pressure transmission ratio. Preoperatively, there was no difference in pressure transmission ratios between urethral pressure profiles associated with leakage of urine and those without urine leakage. Postoperatively, there were differences in pressure transmission ratios between leak and nonleak profiles in the sitting full and supine positions (P less than .001). We could not determine a threshold pressure transmission ratio that was more characteristically associated with leakage of urine. Finally, preoperative pressure transmission ratios were not associated with surgical success, but the higher the postoperative pressure transmission ratio, the more likely the surgery was to be successful (P = .023). In addition, the greater the difference between preoperative and postoperative pressure transmission ratios, the more likely was a cure (P = .011). The pressure transmission ratio may not be helpful in discriminating leak from nonleak dynamic urethral pressure profiles, and there may not be a threshold pressure transmission ratio below which patients characteristically leak urine. However, comparison of preoperative and postoperative pressure transmission ratios is helpful in determining the adequacy of surgical correction of the anatomical defect associated with genuine stress incontinence.

Adult↗
PubMed1988

High pressure and anesthesia: pressure stimulates or inhibits bacterial bioluminescence depending upon temperature.

Although high pressure is often viewed as a nonspecific stimulus counteracting anesthesia, pressure can either excite or inhibit biological activity depending on the temperature at application. Temperature and pressure are two independent variables that determine equilibrium quantity, e.g., the state of organisms in terms of activity and anesthesia depth. We used the light intensity of luminous bacteria (Vibrio fischeri) as an activity parameter, and studied the effects of pressure and anesthetics on the bacteria's light intensity at various temperatures. The light intensity was greatest at about 30 degrees C at ambient pressure. When the system was pressurized up to 204 atm, the temperature for maximum light intensity was shifted to higher temperatures. Above the optimal temperature for the maximal light intensity, high pressure increased the light intensity. Below the optimal temperature, pressure decreased light intensity. Pressure only shifts the reaction equilibrium to the lower volume state (Le Chatelier's principle). When the volume of the excited state is larger than the resting state, high pressure inhibits excitation, and vice versa. Halothane 0.008 atm and isoflurane 0.021 atm inhibited the light intensity both above and below the optimal temperature. When pressurized, the light intensity increased in the high temperature range but decreased in the low temperature range, as in the control. Thus, high pressure seemingly potentiated the anesthetic action at low temperatures. When the ratio of the light intensity in bacteria exposed to anesthesia and those not exposed to anesthesia was plotted against the pressure, however, the value approached unity in proportion to the pressure increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1995

Self-measurement of blood pressure: recommendations of the Canadian Coalition for High Blood Pressure Prevention and Control.

OBJECTIVE: To provide health care professionals with guidelines on the use of blood pressure self-measurement. METHODS: Recommendations were devised after consideration of expert reviews and guidelines, personal files, international standards documents, personal communication with investigators and the results of a MEDLINE search (1966-94) using the term 'blood pressure determination'. BENEFITS, HARMS, COSTS: Self-measurement of blood pressure can be used to detect white coat hypertension, monitor changes in blood pressure closely, more rapidly achieve desired blood pressure goals, increase adherence to antihypertensive therapy and improve patient self-reliance. However, self-measured blood pressure readings may be misleading because there is insufficient normative, prognostic and outcome data and because some patients may not take accurate measurements. The use of self-measurement of blood pressure has a relatively small direct cost and may result in an overall reduction in treatment costs. RECOMMENDATIONS: Self-measured blood pressure readings can be a valuable supplement to clinic (or office) blood pressure readings. However, self-measurement is appropriate neither for patients who are physically or mentally incapable of accurate assessment and interpretation of readings nor for those who do not want to participate. Patients who self-monitor blood pressure require careful training in blood pressure measurement and instruction on the recording and interpretation of blood pressure readings. Advice to patients using monitoring equipment must take into account the needs and abilities of the patient. Although only a few electronic devices for the self-measurement of blood pressure have met recommended performance standards, their use may be more appropriate for some patients and the training requirements fewer than if manual devices are used. VALIDATION: The guidelines of several expert groups were examined in the preparation of these recommendations. The recommendations were presented at the World Conference on Hypertension Control in 1995 and were reviewed by the parent societies of the Canadian Coalition for High Blood Pressure Prevention and Control.

Blood Pressure Determination↗
PubMed1995

Elevated blood pressure during the first two hours of ambulatory blood pressure monitoring: a study comparing consecutive twenty-four-hour monitoring periods.

OBJECTIVE AND DESIGN: Ambulatory blood pressure monitoring is being used increasingly in clinical practice and hypertension research. We have noted elevated blood pressure during the initial hours of monitoring. The objective of the present study was to examine the consistency, magnitude and duration of this elevation, and to determine whether this effect causes significant differences in the mean ambulatory blood pressure monitoring values comparing the first (day 1) and second (day 2) consecutive 24-h periods of monitoring. METHODS: Fifty patients who were hypertensive based on repeated clinic readings were studied prospectively. Each underwent continuous 48-h ambulatory blood pressure monitoring with a SpaceLabs 90207 monitor. The device recorded blood pressure at 15-min intervals during the daytime (0600-2159 h) and at 30-min intervals at night-time (2200-0559 h). From these readings hourly means were calculated. Repeated-measures analysis of variance was performed to compare the hourly means of days 1 and 2. RESULTS: Repeated-measures analysis of variance indicated that a significant difference existed for both systolic and diastolic blood pressure between day 1 and day 2. Paired Student's t-test revealed that this difference occurred during the first 2 h of monitoring. The daytime blood pressure was higher on day 1 as a result of the initial elevation of blood pressure at the onset of monitoring. The initial elevation of blood pressure was present both in white-coat hypertensives and in essential hypertensives. CONCLUSION: The first 2 h of ambulatory blood pressure monitoring are associated with elevated blood pressure both in white-coat hypertensives and in essential hypertensives. This has a minor effect on mean daytime and 24-h ambulatory blood pressures. We propose that improved ambulatory blood pressure monitoring recordings would be obtained in clinical practice, and more particularly in research applications, if 26-h ambulatory blood pressure monitoring was carried out, excluding the first 2 h from the summary analyses.

Adult↗
PubMed1995

[Comparison of invasive blood pressure measurement in the aorta with indirect oscillometric blood pressure measurement at the wrist and forearm].

Indirectly measured blood pressure at the wrist or upper arm was compared with directly measured values in the aortic arch during routinely performed diagnostic cardiac catheterization in 100 patients (31-80 years, mean 59.3 years, 60% males). The noninvasive measurements were carried out by oscillometric devices, NAiS Blood Pressure Watch for measurements at the wrist, and Hestia OZ80 at the upper arm. Systolic blood pressure measured at the wrist was 4.3 +/- 14.1 mm Hg, and the diastolic value 6.0 +/- 8.9 mm Hg higher than when measured at the aortic arch; the difference was significant in both cases. Correlation coefficients were 0.85 for systolic and 0.71 for diastolic blood pressure. In 16% of the patients the systolic blood pressure at the wrist differed more than +/- 20 mm Hg. The diastolic blood pressure at the wrist measured more than +/- 20 mm Hg higher than in the aorta in 5% of the patients. At the upper arm mean systolic values were not different to the aorta. The diastolic pressure was 9.3 +/- 9.8 mm Hg higher in the aorta than at the upper arm. To verify the accuracy of values measured with the NAiS Blood Pressure Watch compared with the standard technique at the upper arm, sequential measurements were made at wrist and ipsilateral upper arm in the same group of 100 patients. The systolic blood pressure at the left wrist was 3.4 +/- 13.3 mm Hg higher and the diastolic pressure 3.8 +/- 9.5 mm Hg lower than at the upper arm. Only 53% of systolic values lay within a range of +/- 10 mm Hg. The correspondence between wrist and upper arm values was better for diastolic blood pressure, the values differing by less than +/- 10 mm Hg in two-thirds of patients. Self-measurement of arterial blood pressure with an oscillometric device at the wrist can be recommended only in individual cases with a difference of simultaneously measured values at the upper arm of less than +/- 10 mm Hg for systolic and diastolic blood pressures. The standard method for indirectly measuring arterial blood pressure remains the measurement at the upper arm site, which nevertheless showed a systolic pseudohypertension (deviation of more than 10 mm Hg) in comparison to the invasively measured values in 15% of our selected patients and a diastolic pseudohypertension (deviation of more than 15 mm Hg) in 23% of the patients.

Adult↗
PubMed1995

The subjective assessment and pressure-flow study of outcome of surgical treatment for patients with prostatism and high voiding pressure.

BACKGROUND: In 1992, the International Continence Society (ICS) began to conduct an international multicenter study to correlate the symptoms and urodynamics in patients with BPH. Our institute was invited to participate this ICS-BPH study, and the preliminary (phase I) results have revealed poor correlation between preoperative symptoms and parameters of the pressure-flow study. This phase II study continued the phase I ICS-BPH study to assess the changes of subjective symptoms and objective parameters of pressure-flow study before and after TURP. METHODS: Fifty-two patients with prostatism, aged from 56 to 80, were evaluated using the ICS-BPH questionnaire, free urine flow rate and pressure-flow study. According to the criteria of maximum urine flow rate (Qmax) 15 ml/sec and voiding intravesical pressure at Qmax (Pves at Qmax) 100 cm H2O, low flow-high pressure (LFHP) was proved in 20 patients (38%), high flow-high pressure (HFHP) in 22 (42%), low flow-low pressure (LFLP) in 3 (6%), and high flow-low pressure (HFLP) in 7 (14%). Transurethral resection of the prostate (TURP) was performed for 33 of 42 patients with high voiding pressure (LFHP and HFHP groups). RESULTS: The weight of the TURP specimen was 28 +/- 6.3 gm. Sixteen patients repeated the questionnaire and pressure-flow study 9.0 +/- 2.1 months after surgery. Both irritative and obstructive symptom scores decreased in 15 (94%) of the 16 patients (p < 0.001). The opening intravesical pressure (openPves) and Pves at Qmax improved from 136 +/- 34 and 124 +/- 30 cm H2O preoperatively to 89 +/- 25 and 94 +/- 22 cm H2O postoperatively respectively (p < 0.004). However, UFRmax, 16.7 +/- 6.0 ml/sec preoperatively and 19.3 +/- 6.4 postoperatively, showed no statistical difference. If the HFHP and LFHP groups were compared separately, the degree of improvement in symptomatology or parameters of pressure-flow study was similar, although changes in HFHP group appeared more evident. UFRmax in LFHP group changed significantly from 11.9 +/- 2.8 preoperatively to 22.1 +/- 6.7 ml/sec postoperatively. For the patients with high flow obstruction (HFHP group), although UFRmax did not increase after TURP, the symptom score, openPves and Pves at Qmax, decreased as much as the LFHP group did. CONCLUSIONS: Based on the analysis of the pressure flow study, TURP not only offers an advantage to the patient with classical obstruction (LFHP group), but also to patients with high flow obstruction (HFHP group). However, this does not suggest that a pressure-flow study should be performed routinely for a male with prostatism. It is advised only for patients with Qmax > 15 ml/sec but exhibiting typical symptoms.

Aged↗
PubMed2005

Intraocular pressure and systemic blood pressure: longitudinal perspective: the Beaver Dam Eye Study.

AIM: To investigate the relation between change in systemic blood pressures and change in intraocular pressure. METHODS: This was a population based study of people 43-86 years old living in Beaver Dam, Wisconsin. Measurements at baseline (1988-90) and 5 year follow up of systemic blood pressures, intraocular pressures, and history of use of blood pressure medications. RESULTS: Intraocular pressures were significantly correlated with systolic and diastolic blood pressures at both baseline and follow up. There were significant direct correlations between changes in systemic blood pressures and changes in intraocular pressure. There was a 0.21 (95% CI: 0.16 to 0.27) mm Hg increase in IOP for a 10 mm Hg increase in systolic and 0.43 (0.35 to 0.52) mm Hg increase in IOP for a 10 mm Hg increase in diastolic blood pressure. Further adjustment for diabetes and medication use did not alter these associations. Decreased systolic or diastolic blood pressures of more than 10 mm Hg over 5 years were significantly associated with decreased IOP. CONCLUSIONS: Reduced systemic blood pressure is associated with reduced intraocular pressure. This finding should be evaluated in other studies, especially with respect to the possibility of resultant decreased risk of open angle glaucoma.

Adult↗
PubMed1992

Pulmonary artery pressure measurement in patients with elevated pressures: effect of backrest elevation and method of measurement.

OBJECTIVE: To determine whether pulmonary artery pressure measurement is accurate if the head of the bed is elevated; to compare the end-expiratory graphic recording and digital monitor methods for pulmonary artery pressure measurement; to determine whether either mean arterial pressure or mixed venous oxygen saturation changes during backrest elevation. DESIGN: Nonrandomized clinical trial. SETTING: A six-bed cardiac surgical intensive care unit of a 540-bed federal facility. POPULATION: Twenty-five postoperative cardiac surgical patients with elevated pulmonary artery pressures (systolic higher than 35 mm Hg). INTERVENTIONS: In supine patients pulmonary artery pressures were measured at each of the following backrest elevations: 0, 20, 30, 45 and again at 0 degrees. Measurements were obtained once during mechanical ventilation and once during normal breathing after extubation. MAIN OUTCOME MEASURES: End-expiratory graphic recording of pulmonary artery pressures; digital monitor values of pulmonary artery pressures; mean arterial pressure; and mixed venous oxygen saturation. RESULTS: No statistical difference was found in pulmonary artery pressures measured at each of the backrest elevations during mechanical ventilation or normal breathing after extubation. Pulmonary artery diastolic and pulmonary capillary wedge pressures obtained with the digital monitor method were significantly lower than the end expiratory graphic recording method during normal breathing after extubation but not during mechanical ventilation. No changes in mean arterial pressure or mixed venous oxygen saturation occurred during backrest elevation. CONCLUSIONS: These results show that pulmonary artery pressures can be measured accurately with the head of the bed in an elevated position. The data indicate that obtaining pulmonary artery pressure measurements from the digital display of the bedside monitor is accurate when respiratory wave form fluctuations are minimal but may lead to inaccurate values with prominent respiratory fluctuations. Further research is needed to validate this finding in different patient populations and with other models of monitoring equipment.

Adult↗
PubMed1994

Rise in systolic blood pressure during sphygmomanometry depends on the maximum inflation pressure of the arm cuff.

OBJECTIVE: Sphygmomanometric recordings of blood pressure are a standard technique in clinical practice. We investigated whether arm-cuff inflation can induce short-term blood pressure changes ('cuff-inflation hypertension'), limiting the generalizability of recordings. METHODS: Progress in biomedical methodology makes it feasible to monitor blood pressure continuously and non-invasively at the finger artery (the Peñaz method). Seventy-two normotensive subjects were randomly assigned either to a series of sphygmomanometric recordings in which a maximum cuff pressure of 300 mmHg was applied, to a series in which the maximum cuff pressure was 175 mmHg or to a control group in whom no sphygmomanometric recordings were made. RESULTS: The subjects exposed to arm-cuff inflations perceived the cuff inflation pressure, but their perception could not differentiate between the two maximum cuff pressures. Furthermore, increases in systolic blood pressure during the inflation period were recorded when a maximum cuff pressure of 300 mmHg was applied. The effects on diastolic blood pressure were not significant. CONCLUSIONS: The maximum arm-cuff pressure during sphygmomanometry should be not too far above the pressure needed to occlude the brachial artery. A high maximum arm-cuff pressure increases the chances of inducing 'cuff-inflation hypertension'.

Adult↗
PubMed1994

[Response of arterial pressure to mental stress in young patients with high or mild arterial hypertension. Does it reflect the changes in arterial pressure observed during its ambulatory monitoring?].

BACKGROUND: The use of cardiovascular reactivity tests in the laboratory is based on their probable capacity to predict blood pressure response in stress situations of everyday life. These responses may be estimated from the values obtained by out patient monitorization or blood pressure (OPMBP). METHODS: OPMBP was carried out over 24 hours by Spacelabs 90202 monitor in 57 subjects from 18-40 years of age with high or slightly high blood pressure (mean blood pressure diagnosed 143 +/- 12/91 +/- 8 mmHg) with a Quetelet index of 25.8 +/- 9 kg/m2. Two mental stress tests were applied: the mental arithmetic test (MAT) and a structured interview (SI) in 38 patients with high or slightly high blood pressure (HBP) and to 18 healthy normotense subjects of the same age group. RESULTS: The increases in systolic BP (SBP) and diastolic BP (DBP) observed during MAT and SI were similar: r = 0.88 and r = 0.68, respectively (p < 0.0001, both). The percentage of hyperreactive subjects, defined as those presenting an absolute increase in SBP > or = 25 mmHg and/or an increase of DBP > or = 15 mmHg was greater between those with slightly high blood pressure (70%) and high blood pressure (43%) in both tests than among the normotense subjects of the control groups (28%) (p < 0.05). Upon study of the relation between response to BP during the mental stress tests and the values of BP obtained with OPBPM, a positive correlation was found between the increase in DBP in MAT and the SI and mean 24 hour DBP (r = 0.39 and r = 0.45, p < 0.025 and p < 0.01, respectively). CONCLUSIONS: The correlation of the absolute increase in systolic and diastolic blood pressure during two different mental stress tests in young subjects with high or slightly high blood pressure is very high. The correlation between the increase in blood pressure to mental stress in the laboratory and the blood pressure values obtained during non invasive out patient monitorization was found to be only intermediate for diastolic blood pressure nad null for systolic blood pressure in this study.

Adolescent↗
PubMed1990

Change of left atrial systolic pressure waveform in relation to left ventricular end-diastolic pressure.

The relation between the left atrial systolic pressure waveform and left ventricular end-diastolic pressure was observed in 17 patients who underwent diagnostic cardiac catheterization. Left atrial pressure and left ventricular pressure were simultaneously recorded from a multisensor catheter before and during angiotensin infusion. Left ventricular systolic pressure and left ventricular end-diastolic pressure were 133 +/- 17 and 12.3 +/- 3.2 mm Hg, respectively, before angiotensin infusion and increased to 168 +/- 18 (p less than 0.01) and 19.4 +/- 4.5 mm Hg (p less than 0.01), respectively, during infusion. The left atrial systolic pressure curve consisted of two positive waves--a first wave (A) and a second wave (A'). The A and A' wave pressures were 11.6 +/- 2.3 and 10.2 +/- 3.9 mm Hg, respectively, before angiotensin infusion and 16.5 +/- 2.9 (p less than 0.01) and 18.1 +/- 4.7 mm Hg (p less than 0.01), respectively, during infusion. The ratio of A'/A of left atrial systolic pressure was 0.81 +/- 0.27 before angiotensin infusion and 1.08 +/- 0.14 (p less than 0.01) during infusion. The ratio of A' to A of left atrial systolic pressure was linearly related to left ventricular end-diastolic pressure before and during (p less than 0.01) angiotensin infusion. The amplitude of the A wave exceeded that of the A' wave at normal left ventricular end-diastolic pressures. However, as the left ventricular end-diastolic pressure increased either at rest or during angiotensin infusion, the amplitude of the A' wave increased and often exceeded that of the A wave. These results suggest that the second (A') wave might be attributed to the increased reflection associated with increased left ventricular end-diastolic pressure.

Adult↗
PubMed1989

Nasal intermittent positive-pressure ventilation offers no advantages over nasal continuous positive airway pressure in apnea of prematurity.

A prospective, randomized, cross-over trial was performed to compare the efficacy of nasal intermittent positive-pressure ventilation with nasal continuous positive airway pressure in infants of less than 32 weeks of gestation. Continuous positive airway pressure was delivered at end-expiratory pressures of 4 cm H2O, while peak pressures of 20 cm H2O and end-expiratory pressures of 4 cm H2O were used during nasal intermittent positive-pressure ventilation at ventilatory rates of 20 breaths per minute. The frequency and extent of apnea and bradycardia during a 6-hour period in a patient receiving nasal continuous positive airway pressure were compared with a similar crossover period of nasal intermittent positive-pressure ventilation. Although the infants had slightly less frequent episodes of apnea per hour (0.6 +/- 0.7 vs 0.5 +/- 0.7) and bradycardia per hour (1.2 +/- 1.3 vs 0.9 +/- 1.0) during nasal intermittent positive-pressure ventilation, these differences were not significant. There were no significant differences in the severity of these events as assessed by the duration and fall in transcutaneous oxygen pressure during apnea and heart rate during bradycardia. There were no significant changes in blood gases throughout the study. Nasal intermittent positive-pressure ventilation appears to have no advantages over nasal continuous positive airway pressure in preventing apnea and does not alter gas exchange in infants of less than 32 weeks of gestation.

Apnea↗
PubMed1986

The role of the pulsatile pressure variations in intracranial pressure monitoring.

The magnitude of the pulsatile intracranial pressure variations (CSF pulse pressure) is determined by the elastance of the craniospinal system and by the magnitude of the pulsatile variations in cerebral blood volume (CBV). The pulsatile change in CBV is, among other factors, determined by the compliance of the cerebral vascular bed which, in its turn, is dependent on the cerebral vasomotor tone. This concept has led the authors to devise a method for the assessment of both the elastance and the state of the cerebral vasomotor tone based on the relationship between CSF pulse pressure and intracranial pressure. This relationship was found to be of a linear nature both in clinical patients and in experimental animals. A significant, positive correlation was found between the slope of this relationship and the value of the craniospinal volume-pressure relationship: the elastance coefficient. During elevation of the intracranial pressure a breakpoint was observed in the relationship between CSF pulse pressure and the intracranial pressure above which the pulse pressure increased more rapidly. The elastance remained constant above this breakpoint. The same phenomenon was observed during plateau waves in clinical patients. Induced changes in systemic arterial pressure produced opposite effects on CSF pulse pressure and elastance coefficient. In these cases the discrepancy between pulse pressure and elastance was attributed to the pulsatile changes in CBV and this could be verified by means of electromagnetic flowmetry. The advantage of this method is that all the information is contained within the intracranial pressure signal itself, from which it can be extracted by simple means without the use of invasive tests.

Animals↗
PubMed1994

Current role of automated ambulatory blood pressure and self-measured blood pressure determinations in clinical practice.

OBJECTIVE: To discuss the clinical indications for use of automated indirect blood pressure measurement (ABPM) and self-monitoring of blood pressure. DESIGN: Available equipment, variations in blood pressure, and settings in which ABPM may be useful are reviewed. RESULTS: Measurement of blood pressure in the physician's office may not reflect the usual blood pressure in other nonmedical environments, such as at work, at home, or during sleep. Self-measurement of blood pressure at home and work and ABPM can provide this additional information. These procedures can be useful not only for determining the presence of office or "white-coat" hypertension but also for assessing patients with both borderline hypertension in the office and target organ damage, those with drug resistance, and cases of episodic hypertension or hypotension. ABPM can also be used to assess very abrupt changes in blood pressure (hypertension or hypotension) and changes in heart rate and blood pressure during sleep. An abbreviated (6-hour) ABPM can be used to confirm increased office blood pressure measurements. Thus, a 6-hour ABPM has the potential to decrease the misclassification of subjects with hypertension or normotension and to limit costs. CONCLUSION: Accurate self-monitored blood pressure measurements can be integrated with office blood pressure determinations to assist in the management of many patients with hypertension. Both ABPM and self-monitoring of blood pressure can improve blood pressure control and practice efficiencies.

Adult↗
PubMed1990

Non-invasive continuous finger blood pressure measurement during orthostatic stress compared to intra-arterial pressure.

STUDY OBJECTIVE: The aim of the study was to evaluate whether invasive blood pressure responses to orthostatic stress can be replaced by non-invasive continuous finger blood pressure responses. DESIGN - Intrabrachial and Finapres blood pressures were simultaneously measured during passive head up tilt and during active standing from the supine or sitting position in healthy volunteers. SUBJECTS: Subjects (n = 11) were healthy males aged 22-40 years, mean age 30 years. MEASUREMENTS AND MAIN RESULTS: Beat to beat values of systolic, diastolic, and mean arterial pressures were calculated for both methods of measurement and the differences compared during a 30 s control period before, and during the first 120 s after, the change of posture. In the control period the difference between finger pressure and intra-arterial pressure was +2 (SD11) mm Hg for systolic, -4(8) mm Hg for mean, and -3(7) mm Hg for diastolic pressure. Compared to these control differences, the average finger minus intra-arterial pressure differences for mean and diastolic pressures during the three orthostatic manoeuvres were always within the range -6 to +6 mm Hg. The average systolic deviations were larger, ranging from -10 to +11 mm Hg. Despite these differences the characteristic changes in intra-arterial pressure during the initial phase (first 30 s after change of posture), as well as during the early steady state phase (1-2 min after the change of posture) were well reflected by finger pressure measurements in all subjects. CONCLUSIONS: For the assessment of the continuous blood pressure responses to orthostatic stress similar information can be obtained with non-invasive Finapres blood pressure recordings as with invasive recordings.

Adult↗
PubMed1991

Aortic-carotid artery pressure differences and cephalic perfusion pressure during cardiopulmonary resuscitation in humans.

OBJECTIVE: Animal studies have shown an aortic-carotid artery pressure difference during cardiopulmonary resuscitation (CPR), which compromises cerebral perfusion. This pressure difference is most marked with prolonged CPR and can be abolished with administration of high doses of epinephrine. To better understand the mechanism of cerebral blood flow during CPR in humans, we determined the aortic-carotid artery pressure difference, the cephalic perfusion pressure (the carotid artery-jugular vein pressure difference), and thoracic inlet venous "valving" (the central venous-jugular vein pressure difference), while administering standard doses of epinephrine. DESIGN: Prospective study with randomization as to which side the carotid artery was catheterized. SETTING: The resuscitation room of a large urban hospital's emergency department. PATIENTS: Fifteen adults in normothermic, nontraumatic prehospital cardiac arrest treated according to Advanced Cardiac Life Support guidelines, including administration of 1 mg epinephrine iv every 5 mins. INTERVENTIONS: The descending aorta, cervical common carotid artery, internal jugular vein, and central venous system were catheterized. Pressures were recorded during standard CPR for 5 mins after administration of 1 mg epinephrine iv. MEASUREMENTS AND MAIN RESULTS: Most patients received CPR for greater than 20 mins before the first epinephrine dose and for greater than 45 mins before pressure recording as described above. There was no significant difference between aortic and carotid artery compression and relaxation phase pressures. The mean +/- SD compression central venous-jugular vein pressure difference was 22.1 +/- 15.0 mm Hg, and the mean cephalic perfusion pressure was 20.8 +/- 19.5 mm Hg. CONCLUSIONS: There is no clinically important aortic-carotid artery pressure difference during human CPR using the standard dose of epinephrine, even with prolonged CPR. Despite carotid artery patency and thoracic inlet venous valving, the cephalic perfusion pressure is low during CPR in humans.

Aged↗
PubMed2004

Wrist blood pressure overestimates blood pressure measured at the upper arm.

OBJECTIVE: Whether blood pressure (BP) measured at the wrist differs from blood pressure measured at the arm is not well known. The aim of this study was to compare the BP readings obtained at the arm with those obtained at the forearm and to assess whether the wrist-arm discrepancies were related to subjects' clinical characteristics. METHODS: We measured blood pressure at the forearm and at the upper arm in 85 subjects using conventional sphygmomanometry. Wrist-arm blood pressure discrepancies were assessed in relation to gender, age, body mass index, skin-fold thickness, arm size, blood pressure level, and arterial compliance measured with the HDI/Pulsewave CR-2000. RESULTS: Blood pressure measured at the wrist consistently overestimated blood pressure taken at the arm with a mean (+/-SD) discrepancy of 8.2 +/- 9.7/9.2 +/- 6.4 mmHg. The systolic blood pressure differences were greater in men than in women (p=0.006) and, among the men, varied according to arm adiposity (positive association, p=0.01). In men, diastolic blood pressure differences correlated with diastolic blood pressure level (negative association, p=0.01). Among the women, only age (p=0.04) was a significant positive independent predictor of the wrist-arm diastolic BP differences. CONCLUSIONS: These results indicate that forearm blood pressure measurement markedly overestimates upper arm blood pressure and that the between-site difference may vary from subject to subject. Wrist blood pressure measurement is not a valid alternative to traditional measurement at the arm and its use should be discouraged.

Adolescent↗