Aortic Diastolic Pressure Research Articles

Abstract 258: Coronary Perfusion Pressure Response to Administration of Intraosseous Epinephrine After Prolonged Cardiac Arrest

Background: While provision of vasopressors during attempted resuscitation of OHCA victims has never been shown to improve neurologically intact survival, its short-term benefits are clear. Despite evidence that the IO dose should be substantially higher than that given IV to achieve pharmacokinetic and hemodynamic equivalency, current guidelines still recommend a dose of 0.01 mg/kg regardless of delivery route (IO or IV). Objective: To compare the effect of epinephrine 0.1 mg/kg (HDE) IO with 0.01 mg/kg (SDE) IV on coronary perfusion pressure (CPP) during resuscitation in a swine model of prolonged VF. Methods: This was a secondary analysis of prospectively collected data from two IACUC approved protocols. Seventy-nine Yorkshire swine (25-30 kg) were surgically instrumented under anesthesia and VF was electrically induced. After 10 minutes of untreated VF in the IO study (n=26) and 12 minutes of untreated VF in the IV study (n=53), resuscitation commenced with precordial chest compressions. After 30 seconds of initial chest compressions, a single dose of epinephrine (HDE IO or SDE IV, respectively) was given followed by a large volume saline flush. An additional 2.5 minutes of compressions were provided after injection to circulate the medication before the first rescue shock (RS) was delivered. CPR and RS attempts were standardized for all animals. The CPP was defined as aortic diastolic pressure minus right atrial diastolic pressure and the values were extracted immediately following the last compression before defibrillation for the first RS in each animal. Descriptive statistics were used to analyze the data. Results: After 10 minutes of untreated VF, HDE IO epinephrine resulted in a mean CPP of 33.2 mmHg (95%CI: 26.6, 39.9) just prior to RS1. After 12 minutes of untreated VF, SDE IV epinephrine resulted in a mean CPP of 25.0 mmHg (95%CI: 20.5, 29.4) just prior to RS1. Conclusion: This observation study reaffirms the assertion that HDE may be required to generate CPP values similar to SDE delivered IV during resuscitation of prolonged VF. A randomized comparison of HDE and SDE IO in the metabolic phase of VF is needed to test this hypothesis and to determine the impact on ROSC and short-term survival.

INCREASED MIDDLE CEREBRAL ARTERY PULSATILITY IN PATIENTS WITH LEUKOARAIOSIS: ENHANCED TRANSMISSION OF AORTIC PULSE WAVES DUE TO INCREASED ARTERIAL STIFFNESS

BackgroundArterial stiffening results in reduced damping of the pulse and increased cerebral arterial pulsatility, which may damage small vessels. We determined the association between leukoaraiosis and aortic and middle cerebral...

Central Hemodynamics in Prehypertension: Effect of the β‐Adrenergic Antagonist Nebivolol

The aim of the current study was to characterize the effects of the novel β-adrenergic antagonist nebivolol on central aortic blood pressures, arterial properties, and nitroxidergic activity in individuals with prehypertension. Prehypertension is emerging as a major risk factor for several adverse cardiovascular consequences. Increased pulse wave velocity, aortic augmentation index, and aortic blood pressures have been linked with augmented risk of cardiovascular disease and mortality. While the effects of antihypertensive drugs on these parameters in hypertensive patients have been studied, there are limited data so far in prehypertension. Fifty individuals with prehypertension were randomized to either nebivolol (5 mg per day) or placebo in a double-blind clinical trial. Patients underwent measurement of pulse wave velocity as well as aortic blood pressure and aortic augmentation index via pulse wave analysis at baseline and 8 weeks. Patients also had blood and urine biochemistries done at each visit. Nebivolol achieved significant reductions in central aortic systolic (P=.011), diastolic (P=.009), and mean arterial blood pressure (P=.002). Pulse wave velocity trended toward improvement but did not achieve significance (P=.088). Nitric oxide production, measured as urinary nitrite/nitrite excretion, also rose substantially in the nebivolol group (by approximately 60%, P=.030). Central blood pressures can be effectively lowered by β-blockade while patients are still in the prehypertension phase, and the effects may be coupled to improve nitric oxide release by the drug.

COMPARISON OF AMIODARONE AND LIDOCAINE IN A PROLONGED VENTRICULAR FIBRILLATION CANINE MODEL

ObjectivesThe purpose of this randomised, experimental canine study was to compare the effect of amiodarone and lidocaine on CPR when given simultaneously with adrenaline in a canine model of prolonged...

COMPARISON OF AMIODARONE AND LIDOCAINE IN A PROLONGED VENTRICULAR FIBRILLATION CANINE MODEL

COMPARISON OF AMIODARONE AND LIDOCAINE IN A PROLONGED VENTRICULAR FIBRILLATION CANINE MODEL

PIOGLITAZONE PREVENTS DIABETES-RELATED ATRIAL FIBRILLATION SUSCEPTIBILITY IN ALLOXAN-INDUCED DIABETIC RABBITS

ObjectivesIn the present study, we investigated underlying mechanisms for the effects caused by pioglitazone, a peroxisomeproliferator-activated receptor (PPAR)-γ activator, on atrial structural remodelling and electrical remodelling in alloxan-induced diabetic rabbits.Methods32...

Increased Cerebral Arterial Pulsatility in Patients With Leukoaraiosis

Arterial stiffening reduces damping of the arterial waveform and hence increases pulsatility of cerebral blood flow, potentially damaging small vessels. In the absence of previous studies in patients with recent transient ischemic attack or stroke, we determined the associations between leukoaraiosis and aortic and middle cerebral artery stiffness and pulsatility. Patients were recruited from the Oxford Vascular Study within 6 weeks of a transient ischemic attack or minor stroke. Leukoaraiosis was categorized on MRI by 2 independent observers with the Fazekas and age-related white matter change scales. Middle cerebral artery (MCA) stiffness (transit time) and pulsatility (Gosling's index: MCA-PI) were measured with transcranial ultrasound and aortic pulse wave velocity and aortic systolic, diastolic, and pulse pressure with applanation tonometry (Sphygmocor). In 100 patients, MCA-PI was significantly greater in patients with leukoaraiosis (0.91 versus 0.73, P<0.0001). Severity of leukoaraiosis was associated with MCA-PI and aortic pulse wave velocity (Fazekas: χ(2)=0.39, MCA-PI P=0.01, aortic pulse wave velocity P=0.06; age-related white matter change: χ(2)=0.38, MCA-PI P=0.015; aortic pulse wave velocity P=0.026) for periventricular and deep white matter lesions independent of aortic systolic blood pressure, diastolic blood pressure, and pulse pressure and MCA transit time with MCA-PI independent of age. In a multivariate model (r(2)=0.68, P<0.0001), MCA-PI was independently associated with aortic pulse wave velocity (P=0.016) and aortic pulse pressure (P<0.0001) and inversely associated with aortic diastolic blood pressure (P<0.0001) and MCA transit time (P=0.001). MCA pulsatility was the strongest physiological correlate of leukoaraiosis, independent of age, and was dependent on aortic diastolic blood pressure and pulse pressure and aortic and MCA stiffness, supporting the hypothesis that large artery stiffening results in increased arterial pulsatility with transmission to the cerebral small vessels resulting in leukoaraiosis.

Cyclooxygenase inhibition augments central blood pressure and aortic wave reflection in aging humans

The augmentation index and central blood pressure increase with normal aging. Recently, cyclooxygenase (COX) inhibitors, commonly used for the treatment of pain, have been associated with transient increases in the risk of cardiovascular events. We examined the effects of the COX inhibitor indomethacin (Indo) on central arterial hemodynamics and wave reflection characteristics in young and old healthy adults. High-fidelity radial arterial pressure waveforms were measured noninvasively by applanation tonometry before (control) and after Indo treatment in young (25 ± 5 yr, 7 men and 6 women) and old (64 ± 6 yr, 5 men and 6 women) subjects. Aortic systolic (control: 115 ± 3 mmHg vs. Indo: 125 ± 5 mmHg, P < 0.05) and diastolic (control: 74 ± 2 mmHg vs. Indo: 79 ± 3 mmHg, P < 0.05) pressures were elevated after Indo treatment in older subjects, whereas only diastolic pressure was elevated in young subjects (control: 71 ± 2 mmHg vs. Indo: 76 ± 1 mmHg, P < 0.05). Mean arterial pressure increased in both young and old adults after Indo treatment (P < 0.05). The aortic augmentation index and augmented pressure were elevated after Indo treatment in older subjects (control: 30 ± 5% vs. Indo 36 ± 6% and control 12 ± 1 mmHg vs. Indo: 18 ± 2 mmHg, respectively, P < 0.05), whereas pulse pressure amplification decreased (change: 8 ± 3%, P < 0.05). In addition, older subjects had a 61 ± 11% increase in wasted left ventricular energy after Indo treatment (P < 0.05). In contrast, young subjects showed no significant changes in any of the variables of interest. Taken together, these results demonstrate that COX inhibition with Indo unfavorably increases central wave reflection and augments aortic pressure in old but not young subjects. Our results suggest that aging individuals have a limited ability to compensate for the acute hemodynamic changes caused by systemic COX inhibition.

A randomized controlled trial investigating the effect of Pycnogenol and BacopaCDRI08 herbal medicines on cognitive, cardiovascular, and biochemical functioning in cognitively healthy elderly people: the Australian Research Council Longevity Intervention (ARCLI) study protocol (ANZCTR12611000487910)

BackgroundOne of the major challenges associated with our ageing population is the increasing incidence of age-associated cognitive decline, which has significant implications for an individual's ability to lead a productive and fulfilling life. In pure economic terms the costs of ageing reflects decreased productivity and engagement with the workforce. The maintenance of brain health underpinning intact cognition is a key factor to maintaining a positive, engaged, and productive lifestyle. In light of this, the role of diet, including supplementation with nutritional and even pharmacological interventions capable of ameliorating the neurocognitive changes that occur with age constitute vital areas of research.MethodsIn order to reduce cognitive ageing, the ARC longevity intervention (ARCLI) was developed to examine the effects of two promising natural pharmacologically active supplements on cognitive performance. ARCLI is a randomized, placebo-controlled, double-blind, 3-arm clinical trial in which 465 participants will be randomized to receive an extract of Bacopa monnieri (CDRI08 300 mg/day), Pycnogenol (150 mg/day), or placebo daily for 12 months. Participants will be tested at baseline and then at 3, 6 and 12 months post-randomization on a wide battery of cognitive, neuropsychological and mood measures, cardiovascular (brachial and aortic systolic and diastolic blood pressures as well as arterial stiffness), biochemical (assays to measure inflammation, oxidative stress and safety) as well as genetic assessments (telomere length and several Single Nucleotide Polymorphisms). The primary aim is to investigate the effects of these supplements on cognitive performance. The secondary aims are to explore the time-course of cognitive enhancement as well as potential cardiovascular and biochemical mechanisms underpinning cognitive enhancement over the 12 months of administration.ARCLI will represent one of the largest and most comprehensive experimental clinical trials in which supplements are administered to elderly participants. Results from ARCLI may help develop novel preventative health practices and nutritional/pharmacological targets in the elderly for cognitive and brain health.Trial registrationAustralia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12611000487910

Non-invasive measurement of aortic pressure in patients: Comparing pulse wave analysis and applanation tonometry.

Objective:The aim of the present study was to validate and compare novel methods to determine aortic blood pressure non-invasively based on Oscillometric Pulse Wave Velocity (PWV) measurement using four limb-cuff pressure waveforms and two lead Electrocardiogram (ECG) with a validated tonometric pulse wave analysis system in patients.Materials and Methods:After receiving the consent, in 49 patients with hypertension, coronary artery disease, diabetes mellitus, PWV, and central blood pressures were recorded in a randomised manner using both the oscillometric and tonometric devices. All recordings were performed 10 minutes after the patient lying comfortably in a noise-free temperature-controlled room. The test was performed between 09 am and 10 am after overnight fast. A minimum of three measurements were performed by the same skilled and trained operator. From the raw data obtained with two devices, software calculated the final vascular parameters.Results:A total of 49 patients (8 women and 41 men), of mean age 40.5 years (range: 19-81 years) participated in the present study. After transforming the brachial pressures into aortic pressures, the correlation coefficient between the Aortic Systolic Pressure (ASP) values obtained with two methods was 0.9796 (P<0.0001). The mean difference between ASP with two methods was 0.3 mm Hg. Similarly, Aortic Diastolic Pressure (ADP) values obtained with two methods also correlated significantly with correlation coefficient of 0.9769 (P<0.0001). The mean difference of ADP was 0.2 mm Hg. In case of Aortic Pulse Pressure (APP), the mean difference was 0.1 mm Hg. All parameters of central aortic pressures obtained with two methods correlated significantly.Conclusion:The new method of transforming the Carotid Femoral PWV (cfPWV) and brachial blood pressure values into aortic blood pressure values seems to be reasonably good. The significant correlation between the values obtained by tonometric device and oscillometric PWV method shows that the latter can be used non-invasively in patients to find the aortic pressure.

Serum 25-hydroxyvitamin D and Ethnic Differences in Arterial Stiffness and Endothelial Function

BackgroundVitamin D reportedly influences vascular function, which is worse in African Americans (AAs) relative to European Americans (EAs). It is not clear if ethnic differences in 25(OH)D mediate differences in vascular function. This study examined the relationships of serum 25-hydroxyvitamin D (25(OH)D) with indicators of vascular function among healthy, young AA and EA adults.MethodsThis is a cross sectional study involving 23 AAs and 22 EAs. The main outcomes were augmentation index (AIx75), central aortic pressure, pulse wave velocity (PWV), flow-mediated dilation (FMD), and seated and supine blood pressures.ResultsResults indicated that 25(OH)D was inversely associated with AIx75, supine systolic blood pressure (SBP), central aortic SBP and central aortic diastolic blood pressure (DBP), independent of age, sex, and percent body fat (standardized β= -0.29 to -0.43, P < 0.05 for all). AAs had greater AIx75 (P = 0.04) and PWV (P = 0.07) and lower FMD (P = 0.02) compared to EA after adjusting for age and percent body fat; further adjustment for 25(OH)D reduced the ethnic differences (P = 0.44, 0.53, and 0.20, respectively).ConclusionThe 25(OH)D was associated with vascular function in healthy adults, and lower 25(OH)D among AAs may contribute to their greater arterial stiffness and reduced endothelial function (Clinical trials.gov NCT01041365, NCT01041547).

Abstract 61: A Novel Electrical Therapy for Postshock PEA in a Porcine Model

BACKGROUND: Chest compression (CC) is currently recognized as the only effective intervention for the treatment of shock induced pulseless electrical activity (PEA). This study was designed to test a new form of therapy, packet electrical therapy (PET), for post shock PEA in a porcine model using medium energy electrical pacing. The main objective was to compare hemodynamic responses between the PET and the standard CC. METHODS: In 12 domestic pigs weighing 22-24kg, ventricular fibrillation (VF) was electrically induced and untreated for 2 to 7 minutes before delivering shock to induce post shock PEA with peak aortic pressures below 40 mm Hg. Once the PEA was induced, animals received 15 sec PET followed by 45 sec standard CC, and followed by 15 sec PET combined with the standard CC in sequence. If animals were resuscitated after the study sequence, after 30 minutes recovery, PEA induction and the study sequence were repeated. PET consisted of a train of narrow pulses with the amplitude of 2 amperes and the total duration of 200 ms, the depth of standard CC was maintained at 2 inches of the anterior posterior diameter of the thorax. RESULTS: A total of 35 qualified PEA events from 9 animals were included in the analyses as shown in the table: CONCLUSION: No significant differences were detected between coronary perfusion pressures for PET as compared to standard chest compressions. Both aortic and right atrial diastolic pressures were significantly increased with PET.

Norwood with right ventricle-to-pulmonary artery conduit is more effective than Norwood with Blalock–Taussig shunt for hypoplastic left heart syndrome: mathematic modeling of hemodynamics

The introduction of right ventricle to pulmonary artery (RV-PA) conduit in the Norwood procedure for hypoplastic left heart syndrome resulted in a higher survival rate in many centers. A higher diastolic aortic pressure and a higher mean coronary perfusion pressure were suggested as the hemodynamic advantage of this source of pulmonary blood flow. The main objective of this study was the comparison of two models of Norwood physiology with different types of pulmonary blood flow sources and their hemodynamics. Based on anatomic details obtained from echocardiographic assessment and angiographic studies, two three-dimensional computer models of post-Norwood physiology were developed. The finite-element method was applied for computational hemodynamic simulations. Norwood physiology with RV-PA 5-mm conduit and Blalock-Taussig shunt (BTS) 3.5-mm shunt were compared. Right ventricle work, wall stress, flow velocity, shear rate stress, energy loss and turbulence eddy dissipation were analyzed in both models. The total work of the right ventricle after Norwood procedure with the 5-mm RV-PA conduit was lower in comparison to the 3.5-mm BTS while establishing an identical systemic blood flow. The Qp/Qs ratio was higher in the BTS group. Hemodynamic performance after Norwood with the RV-PA conduit is more effective than after Norwood with BTS. Computer simulations of complicated hemodynamics after the Norwood procedure could be helpful in establishing optimal post-Norwood physiology.

Influence of Aortic Elastic Properties on Pulse Pressure Changes Induced by Rapid Ventricular Pacing.

The mechanism of aortic pulse pressure decline induced by acute rapid ventricular pacing remains incompletely understood. It has been ascribed to changes in stroke volume or aortic compliance. This becomes more complicated by the dependence of aortic compliance on the level of the mean aortic pressure as well as the aortic wall properties. To test the role of such mechanical factors, aortic pressure-diameter hemodynamics, derived from simultaneous tip-micromanometer aortic pressure recordings and high-fidelity ultrasonic intravascular aortic diameter recordings, were measured in 15 normal subjects during and after abrupt cessation of rapid ventricular pacing (up to 160 bpm). Immediately after terminating the pacing, diastolic aortic pressure declined (-9%, from 87.4 +/- 1.2 to 79.5 +/- 1.7 mmHg, P < 0.0001) while systolic aortic pressure increased (+19%, from 109.5 +/- 1.6 to 130.1 +/- 2.8 mmHg, P < 0.0001). Thus, pulse pressure increased from 22.1 +/- 2.2 to 50.6 +/- 3.1 mmHg, P < 0.0001. To quantify systolic and diastolic aortic pressure differences we compared the first postpaced beat (a) and the last paced beat (b). To estimate what the aortic pressure would have been for the paced beats had the aortic diameter differences due to the different heart rate not occurred we calculated the theoretical pressure of the paced beat P(b) = E(b). D(a), where E(b) was the instantaneous aortic elastance of the paced beat and D(a) was the aortic diameter for the postpaced beat. The corrected pressure difference was then calculated by the following: DeltaP(cor) = (D(a). E(b)) - P(a). It was found that systolic DeltaP(cor) was 25% of systolic DeltaP(raw) and diastolic DeltaP(cor) was 89% of diastolic DeltaP(raw). DeltaP(raw) was the pressure difference between paced and spontaneous beat measured from the raw data. DeltaP(cor) indicates the portion of DeltaP(raw) that results from a change in aortic stiffness as a consequence of viscous behavior or aorto-ventricular coupling. These data indicate that the majority of diastolic pressure decline after pacing was terminated, may reflect a change in aortic stiffness while the majority of systolic pressure rise, and may be attributable to differences in hemodynamics alone.

Diastolic Pressure Gradient in the Ascending Aorta Caused by the Mobile Intimal Flap of Dissecting Aneurysm.

Aortic regurgitation is a serious complication of ascending aortic dissection. We report a 65-year-old man with Type A aortic dissection and aortic regurgitation who presented with a diastolic aortic pressure gradient along the aortic root which was caused by a large intimal flap interrupting the diastolic regurgitant flow.

Resistance exercise training does not affect postexercise hypotension and wave reflection in women with fibromyalgia

The purpose of this study was to assess the effects of resistance exercise training (RET) on aortic wave reflection and hemodynamics during recovery from acute resistance exercise in women with fibromyalgia (FM) and healthy women (HW). Nine women with FM (aged 42± 5years; mean± SD) and 14 HW (aged 45± 5years) completed testing at baseline and after 12weeks of whole-body RET that consisted of 3 sets of 5 exercises. Heart rate (HR), digital blood pressure (BP, plethysmography), aortic BP, and wave reflection (radial tonometry) were assessed before and 20min after acute leg resistance exercise. Aortic and digital diastolic blood pressure (DBP) were significantly decreased (p< 0.05) and aortic and digital pulse pressures (PP) were significantly increased (p< 0.05) after acute exercise before RET. Acute resistance exercise had no effect on HR, wave reflection (augmentation index and reflection time), digital, or aortic systolic BP. RET improved muscle strength without affecting acute DBP and PP responses. Acute resistance exercise produces postexercise diastolic hypotension without affecting systolic blood pressure, HR, and wave reflection responses in women with and without FM. RET does not alter resting and postexercise hemodynamics and aortic wave reflection in premenopausal women.

The relation of non-invasively and invasively assessed aortic pulsatile indices to the presence and severity of coronary artery disease

Objectives. The aim of the study was to assess the relationship between non-invasively (NIA) and invasively assessed (IA) aortic pulsatile indices and the presence and severity of coronary artery disease (CAD). Subjects and Methods. The study group consisted of 58 patients who were admitted to our institute for elective coronary angiography (CAG). We measured the aortic systolic, diastolic and mean blood pressure (BP) using non-invasive and invasive techniques. We assessed the pulsatile indices of the aortic pressure waveform (APW) including pulse pressure (PP), fractional PP (FPP, the ratio of PP to mean BP) and pulsatility index (PI, the ratio of PP to diastolic BP). The severity of CAD was assessed by Gensini score. Results. IA aortic PP, FPP and PI were significantly higher in patients with CAD than without CAD, but NIA indices did not show significant differences between two groups. After multivariate stepwise adjustment, the odds ratio (OR) and confidence interval (CI) of having significant CAD was: PP per 10 mmHg, OR = 2.51 (95% CI 1.12–5.63); FPP per 0.1, OR = 3.30 (95% CI 1.25–8.72); and PI per 0.1, OR = 1.88 (95% CI 1.09–3.23). In linear regression analysis, IA aortic systolic BP (SBP), PP, FPP and PI were significantly correlated with Gensini score, but NIA indices were not correlated. The NIA aortic PP was lower than IA aortic PP (mean difference: 6.1 ± 15.8 mmHg). Conclusion. IA aortic PP, FPP and PI were related to the presence and severity of CAD, but NIA assessed indices of APW were not related. NIA aortic PP underestimated IA aortic PP.

Characteristics of hemodynamics during closed chest cardiopulmonary resuscitation

Objective To study the hemodynamics during closed chest cardiopulmonary resuscitation (CCCPR) in dogs in order to unravel the mechanism. Method Twelve healthy mongrel dogs were selected to make animal model of ventricular fibrillation induced by electric shock on the chest wall. Closed-chest cardiopulmonary resuscitation (CCCPR) was initiated four minutes after ventricular fibrillation appeared according to American Heart Guidelines in 2005 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Rescue. After CPR for 2 minutes, 1mg epinephrine was injected intravenously. The central venous pressure (CVP), the aortic pressure (AOP)and the invasive electrocardiogram (ECG) were used to monitor continuously before ventricular fibrillation and the entire course of CPR. The coronary perfusion pressure (CPP) was calculated. The changes in aortic diastolic pressure (ADP) and CPP produced by chest compression or the injection of epinephrine were analyzed. The aortic pressure and the central venous pressure were recorded simultaneously during CPR. A chart was made and the CPP was calculated with the software Chart5Ch. The hemodynamic changes produced by the administration of epinephrine were studied. Data were analyzed with paired Student t test. P ＜ 0.05 was considered as a significant difference. Results Two kinds of hemodynamic effects of CPR were observed. In 8 dogs (8/12) , the aortic pressure changed synchronously with the CVP, and the CPP was almost zero, and in other 4 dogs (4/12), the aortic pressure increased and the CVP remained unchanged with presence of the CPP. After the administration of epinephrine, the AOP and the CPP increased significantly. The Aortic systolic pressure(ASP) increased from (66± 14) mmHg to(107 ± 28) mmHg, (P = 0. 001). The Aortic diastolic pressure (ADP) increased from (25 ±2.2) mmHg to(45 ± 13) mmHg (P =0.001). And the coronary perfusion pressure (CPP) increased from (2.8± 3.8) mmHg to (29 ± 13) mmHg (P ＜ 0.001). The 95 % confidential interval of the added value of the ASP,ADP and CPPwere (21.1-59.1), (10.2-28.3) and (16.7-35.7), respectively. Conclusions The thoracic pump mechanism is the primary role in the closed chest Cardiopulmonary resuscitation. Epinephrine can increase ADP and CPP and has the capability to break the balance between aortic pressure and central venous pressure, increasing the rate of successful cardiopulmonary resuscitation. Key words: Cardiopulmonary resuscitation; Closed chest; Hemodynamics; Epinephrine; Mechanism

Measurement Accuracy of Non-invasively Obtained Central Blood Pressure: A Systematic Review and Meta-analysis

Blood pressures determined at different sites vary considerably. Non-invasive methods are available to estimate central aortic blood pressure, the blood pressure at the origin of all arterial pulses. These methods obtain estimated central blood pressure by calibration and/or mathematical calculations for peripheral pulse waveforms. However, the accuracy of these methods has not been systematically examined.The review aimed to synthesise the best evidence on the accuracy of non-invasive measurement methods for central blood pressure.Types of participantsStudies with adult patients receiving invasive and non-invasive measurements of central blood pressure were considered.Studies were considered for inclusion if the focus was accuracy of non-invasive central BP estimating methods compared to invasively obtained corresponding values.Studies examining agreement between measurements using non-invasive central blood pressure estimating methods compared to invasive corresponding values were considered.This review included the means and standard deviation of differences between estimated and invasively measured central blood pressure.The search sought to identify any relevant published or unpublished studies with a three-step search strategy.Two independent reviewers assessed methodological quality of studies by a critical appraisal tool modified from Cochrane Diagnostic Test Accuracy Working Group.We used an original form to extract from included studies all study characteristics possibly related to agreement.Inverse variance weighted approach and DerSimonian-Laird weights for the random effects model, which incorporates a between-study variance, were used to obtain pooled estimates of systematic and random error from individual study estimates of the mean and standard deviation of differences between the paired measurements. Heterogeneity was assessed using Cochran Q. All analyses were performed in Microsoft Excel 2003.Twenty eight studies were eligible for inclusion and critically appraised in this review. Appropriate data for agreement were extracted from papers or authors in 20 studies, which were further included in meta-analysis. Acquired peripheral waveforms in these studies were directly measured, calibrated to match invasively obtained aortic mean blood pressure and diastolic blood pressure, or calibrated using brachial blood pressure measured by sphygomomanometer, the cuff blood pressure. Estimated central blood pressure of the studies using the last totally non-invasively methods (real world practices) were subject to meta-analysis separately from studies with the former two invasive methods (theoretical practice). Of the invasive methods, mean difference of the estimated central blood pressure was small (-1.2 ± 4.2mmHg for central systolic blood pressure, -0.6 ± 2.1mmHg for central diastolic blood pressure, and -1.1 ± 5.3 mmHg for central pulse pressure). However, the errors of the non-invasive method inflated considerably (-8.1 ± 10.7mmHg for central systolic blood pressure, 8.8 ± 9.5mmHg for central diastolic blood pressure, and -11.8 ± 13.3 mmHg for central pulse pressure). The findings were similar in subgroup analysis by different central blood pressure methods and by validated cuff monitors.Current central blood pressure estimating methods are acceptable in theory with small systematic and random error. However, the error of these methods was evident when cuff blood pressure was used for calibration and probably made them clinically inapplicable.

Measurement Accuracy of Non-invasively Obtained Central Blood Pressure: A Systematic Review and Meta-analysis.

Blood pressures determined at different sites vary considerably. Non-invasive methods are available to estimate central aortic blood pressure, the blood pressure at the origin of all arterial pulses. These methods obtain estimated central blood pressure by calibration and/or mathematical calculations for peripheral pulse waveforms. However, the accuracy of these methods has not been systematically examined. The review aimed to synthesise the best evidence on the accuracy of non-invasive measurement methods for central blood pressure. Types of participantsStudies with adult patients receiving invasive and non-invasive measurements of central blood pressure were considered. Studies were considered for inclusion if the focus was accuracy of non-invasive central BP estimating methods compared to invasively obtained corresponding values. Studies examining agreement between measurements using non-invasive central blood pressure estimating methods compared to invasive corresponding values were considered. This review included the means and standard deviation of differences between estimated and invasively measured central blood pressure. The search sought to identify any relevant published or unpublished studies with a three-step search strategy. Two independent reviewers assessed methodological quality of studies by a critical appraisal tool modified from Cochrane Diagnostic Test Accuracy Working Group. We used an original form to extract from included studies all study characteristics possibly related to agreement. Inverse variance weighted approach and DerSimonian-Laird weights for the random effects model, which incorporates a between-study variance, were used to obtain pooled estimates of systematic and random error from individual study estimates of the mean and standard deviation of differences between the paired measurements. Heterogeneity was assessed using Cochran Q. All analyses were performed in Microsoft Excel 2003. Twenty eight studies were eligible for inclusion and critically appraised in this review. Appropriate data for agreement were extracted from papers or authors in 20 studies, which were further included in meta-analysis. Acquired peripheral waveforms in these studies were directly measured, calibrated to match invasively obtained aortic mean blood pressure and diastolic blood pressure, or calibrated using brachial blood pressure measured by sphygomomanometer, the cuff blood pressure. Estimated central blood pressure of the studies using the last totally non-invasively methods (real world practices) were subject to meta-analysis separately from studies with the former two invasive methods (theoretical practice). Of the invasive methods, mean difference of the estimated central blood pressure was small (-1.2 ± 4.2mmHg for central systolic blood pressure, -0.6 ± 2.1mmHg for central diastolic blood pressure, and -1.1 ± 5.3 mmHg for central pulse pressure). However, the errors of the non-invasive method inflated considerably (-8.1 ± 10.7mmHg for central systolic blood pressure, 8.8 ± 9.5mmHg for central diastolic blood pressure, and -11.8 ± 13.3 mmHg for central pulse pressure). The findings were similar in subgroup analysis by different central blood pressure methods and by validated cuff monitors. Current central blood pressure estimating methods are acceptable in theory with small systematic and random error. However, the error of these methods was evident when cuff blood pressure was used for calibration and probably made them clinically inapplicable.