Intra-arterial Blood Pressure Research Articles

Anesthesia During Positive-pressure Myelogram: A New Role for Cerebral Oximetry.

Positive-pressure myelogram (PPM) is an emerging radiologic study used to localize spinal dural defects. During PPM, cerebrospinal fluid pressure (CSFp) is increased by injecting saline with contrast into the cerebrospinal fluid. This has the potential to increase intracranial pressure and compromise cerebral perfusion. We performed a retrospective chart review and analysis of 11 patients. The aim was to describe the periprocedural anesthetic management of patients undergoing PPM. All patients underwent PPM with general anesthesia and intra-arterial blood pressure and near-infrared spectroscopy monitoring of regional cerebral tissue oxygen saturation. Mean±SD maximum lumbar CSFp was 58±12 mm Hg. Upon intrathecal injection, mean systolic blood pressure increased from 115±21 to 142±32 mm Hg (P<0.001), diastolic blood pressure from 68±12 to 80±20 mm Hg (P≤0.001), and mean blood pressure from 87±10 to 98±14 mm Hg (P=0.02). Ten of 11 patients received blood pressure augmentation with phenylephrine to minimize the risk of reduced cerebral perfusion secondary to increased CSFp after intrathecal injection. The mean heart rate before and following injection was similar (68±15 vs. 70±15 bpm, respectively; P=0.16). There was a decrease in regional cerebral oxygen saturation after positioning from supine to prone position (79±10% to 74±9%, P=0.02) and a further decrease upon intrathecal injection (75±10% to 69±9%, P≤0.01). Systemic blood pressure increased following intrathecal injection during PPM, possibly due to a physiologic response to intracranial hypertension/reduced cerebral perfusion or administration of phenylephrine. Regional cerebral oxygen saturation decreased with the change to prone position and further decreased upon intrathecal injection. Cerebral near-infrared spectroscopy has a potential role to monitor the adequacy of cerebral perfusion and guide adjustment of systemic blood pressure during PPM.

TLR (Toll-Like Receptor) 4 Antagonism Prevents Left Ventricular Hypertrophy and Dysfunction Caused by Neonatal Hyperoxia Exposure in Rats.

Preterm birth is associated with proinflammatory conditions and alterations in adult cardiac shape and function. Neonatal exposure to high oxygen, a rat model of prematurity-related conditions, leads to cardiac remodeling, fibrosis, and dysfunction. TLR (Toll-like receptor) 4 signaling is a critical link between oxidative stress, inflammation, and the pathogenesis of cardiovascular diseases. The current study sought to investigate the role of TLR4 signaling in neonatal oxygen-induced cardiomyopathy. Male Sprague-Dawley pups were kept in 80% oxygen or room air from day 3 to 10 of life and treated with TLR4 antagonist lipopolysaccharide from the photosynthetic bacterium Rhodobacter sphaeroides(LPS-RS) or saline. Echocardiography was performed at 4, 7, and 12 weeks. At 12 weeks, intraarterial blood pressure was measured before euthanization for histological and biochemical analyses. At day 10, cardiac TLR4, Il (interleukin) 18, and Il1β expression were increased in oxygen-exposed compared with room air controls. At 4 weeks, compared with room air-saline, saline-, but not LPS-RS treated-, oxygen-exposed animals, exhibited increased left ventricle mass index, reduced ejection fraction, and cardiac output index. Findings were similar at 7 and 12 weeks. LPS-RS did not influence echocardiography in 12 weeks room air animals. Systolic blood pressure was higher in saline- but not LPS-RS treated-oxygen-exposed animals compared with room air-saline and -LPS-RS controls. LPS-RS prevented cardiac fibrosis and cardiomyocytes hypertrophy, the increased TLR4, Myd88, and Il18 gene expression, TRIF expression, and CD68+ macrophages infiltration associated with neonatal oxygen exposure, without impact in room air rats. This study indicates that neonatal exposure to high oxygen programs TLR4 activation, which contributes to cardiac remodeling and dysfunction.

Noninvasive Determination of Blood Pressure by Heart Sound Analysis Compared With Intra-Arterial Monitoring in Critically Ill Children-A Pilot Study of a Novel Approach.

To develop a novel device to predict systolic and diastolic blood pressure based on measured heart sound signals and evaluate its accuracy in comparison to intra-arterial blood pressure readings. Prospective, observational pilot study. PICU. Critically ill children (0-18 yr) undergoing continuous blood pressure monitoring via radial artery intra-arterial catheters were enrolled in the study after informed consent. The study included medical, cardiac, and surgical PICU patients. Along with intra-arterial blood pressure, patient's heart sounds were recorded simultaneously by a highly sensitive sensor taped to the chest. Additional hardware included a data acquisition unit and laptop computer. Subsequently, advanced signal processing technologies were used to minimize random interfering signals and extract and separate S1 and S2 signals. A computerized model was then developed using artificial neural network systems to estimate blood pressure from the extracted heart sound analysis. We found a statistically significant correlation for systolic (r = 0.964; R = 0.928) and diastolic (r = 0.935; R = 0.868) blood pressure readings (n = 491) estimated by the novel heart-sound signal-based method and those recorded by intra-arterial catheters. The mean difference of the individually paired determinations of the blood pressure between the heart-sound-based method and intra-arterial catheters was 0.6 ± 7 mm Hg for systolic blood pressure and -0.06 ± 5 mm Hg for diastolic blood pressure, which was within the recommended range of 5 ± 8 mm Hg for any new blood pressure devices. Our findings provide proof of concept that the heart-sound signal-based method can provide accurate, noninvasive blood pressure monitoring.

Association Between Intra-arterial Invasive Central and Peripheral Blood Pressure and Endothelial Function (Assessed by Flow-Mediated Dilatation) in Stable Coronary Artery Disease

Endothelial function is an independent predictor of coronary artery disease (CAD) and is regulated by a number of factors, including blood pressure. The current study was designed to test the hypothesis that intra-arterial invasive central blood pressure is strongly associated with endothelial function in patients with CAD. In patient with CAD (diameter stenosis ≥30%), invasive central (aortic) and left peripheral (brachial) blood pressures were determined during transradial coronary angiography. The endothelial function was evaluated by way of flow-mediated dilatation (FMD) of the brachial artery. We enrolled 413 consecutive patients. There were 260 patients with significant CAD (sCAD, diameter stenosis ≥50%) and 153 patients with nonsignificant CAD (nsCAD, diameter stenosis <50% and ≤30%). FMD was significantly and inversely correlated with central and peripheral parameters in terms of systolic blood pressure, mean arterial pressure, and pulse pressure (PP) (r = -0.332, r = -0.184, and r = -0.407, respectively, all P < 0.001) and (r = -0.303, r = -0.190, and r = -0.319, respectively, all P < 0.001). Compared with sCAD, there was closer correlation between central PP with FMD in nsCAD (r = -0.548 vs. r = -0.345, both P < 0.001). After adjusting potential confounders such as age, body mass index and high-sensitivity C-reactive protein, multivariate analysis showed that FMD remained independently associated with central PP, degree of coronary artery stenosis, and brachial-ankle pulse wave velocity in all patients. In patients with nsCAD, the multivariate analysis showed that only central PP was independently correlated with FMD. In patients with stable CAD, a decline in endothelial function is most closely associated with invasive central pulse pressure.

Hypotension Prediction Index software for management of hypotension during moderate- to high-risk noncardiac surgery: protocol for a randomized trial

BackgroundHypotension is associated with serious complications, including myocardial infarction, acute kidney injury, and mortality. Consequently, predicting and preventing hypotension may improve outcomes. We will therefore determine if use of a novel hypotension prediction tool reduces the duration and severity of hypotension in patients having non-cardiac surgery.Methods/designWe will conduct a two-center, pragmatic, randomized controlled trial (N = 213) in noncardiac surgical patients > 45 years old who require intra-arterial blood pressure monitoring. All participating patients will be connected to a Flortrac IQ sensor and EV1000 platform (Edwards Lifesciences, Irvine). They will be randomly assigned to blinded or unblinded arms. The Hypotension Prediction Index (HPI) and advanced hemodynamic information will be universally recorded, but will only be available to clinicians when patients are assigned to unblinded monitoring. The primary outcome will be the effect of HPI software guidance on intraoperative time-weighted average mean arterial pressure under a threshold of 65 mmHg, which will be assessed with a Wilcoxon-Mann-Whitney 2-sample, two-tailed test.DiscussionOur trial will determine whether the Hypotension Prediction Index and associated hemodynamic information substantively reduces hypotension during non-cardiac surgery.Trial registrationClinicalTrials.gov, NCT03610165. Registered on 1 August 2018.

Brachial and Radial Systolic Blood Pressure Are Not the Same.

Radial intra-arterial blood pressure (BP) is sometimes used as the reference standard for validation of brachial cuff BP devices. Moreover, there is an emerging wearables market seeking to measure BP at the wrist. However, radial systolic BP may differ when compared with brachial; yet some authors have labeled these differences as a fictional Popeye phenomenon. Indeed, differences between brachial and radial systolic BP have never been accurately quantified, and this was the aim of this study. Intra-arterial BP was measured consecutively at the brachial and radial artery in 180 participants undergoing coronary angiography (aged 61±10 years; 69% men). On average, radial systolic BP was 5.5 mm Hg higher than brachial systolic BP. Only 43% of participants had radial systolic BP within ±5 mm Hg of brachial. Additionally, 46%, 19%, and 13% of participants had radial systolic BP >5, between 5 and 10, and between 10 and 15 mm Hg higher than brachial respectively. A further 14% of participants had radial systolic BP >15 mm Hg higher than brachial, representing the so-called Popeye phenomenon. Finally, 11% of participants had radial systolic BP >5 mm Hg lower than brachial. In conclusion, radial systolic BP is not representative of brachial systolic BP, with most participants having a radial systolic BP >5 mm Hg higher than brachial and many with differences >15 mm Hg. Therefore, validation testing of BP devices utilizing intra-arterial BP as the reference standard should use intra-arterial BP measured at the same site as the brachial cuff or wearable device.

HP-01-004 The effects of antifibrotic agent-pirfenidone on penile cavernous function in experimental ischaemic priapism-induced rat model

Aim of the study was to assess the impact of an antifibrotic and anti inflammatory agent-pirfenidone in an experimental ischemic rat priapism model. 0Forty-eight male Albino-Wistar rats were randomized into four groups (n=12 in each group): Group-1 (non-priapism, no-medication), Group-2 (one-hour priapism, no-medication), Group-3 (one-hour priapism, six-weeks followup, no-medication), and Group-4 (one-hour priapism, six-weeks pirfenidone). Erection model was created by electrical stimulation of the cavernous nerve. The intracavernosal pressure (ICP) and the blood pressure were recorded (Fig. 1a). Degree of the fibrosis were evaluated as (+), (++), (+++), and (++++) using Masson's trichrome strain. Malondialdehyde (MDA) and reducted glutathione (GSH) levels were measured by spectrophotometric method. Statistical analyses were performed with SPSS program for windows. Group-2 and 3 showed marked cavernosal fibrosis following the formation of an ischemic priapism model. In contrast, Group-4 showed significant decrease in fibrosis compared to Group-3 (Fig. 1b). The mean basal ICP (BICP), maximum ICP (MICP), mean ICP (MeICP), the difference between MICP and BICP (DICP), area under curve (AUC), and the ratio of MeICP/ mean intraarterial blood pressure (MIBP) were recorded. In Group-2, all these parameters showed significant decrease compared to Group-1 (p<0.05). The mean MICP, MeICP and the MeICP/MIBP ratios significantly decreased in Group-3 compared to Group-1 (p<0.05). The mean BICP, MICP, MeICP, DICP, AUC, and MeICP/MIBP values were similar in Group-1 and 4 (p>0.05) (Fig. 1c). Group-4 showed a statistically significant decrease in cavernosal mean MDA levels compared to Group-3, (p<0.05). Group 4 showed a statistically significant increase in the mean GSH levels compared to Group-3 (p<0.05) (Fig. 1d).

SAT-057 Endoplasmic Reticulum Aminopeptidase-1 Is a Novel Regulator of the Renin-Angiotensin-Aldosterone System and Blood Pressure Homeostasis

Endoplasmic Reticulum Aminopeptidase-1 (ERAP1) has been proposed to metabolize angiotensin II (ANGII), an effector molecule of the renin-ANGII-aldosterone (ALDO) system (RAAS) and key regulator of volume and blood pressure (BP) homeostasis. ERAP1 plays an important role in immune function as it cleaves cytokine cell surface receptors and HLA binding precursors thereby modulating their inclusion into major histocompatibility complex-I (MHC). Indeed, absence of ERAP1 in vivo shows MHC-I peptide presentation defects and decreased T regulatory cells in mice. However, the interaction between ERAP1 and RAAS remains unclear. We hypothesized that ERAP1 mediates the interaction between BP homeostasis and cardiorenal disease. We studied ERAP1 deficient heterozygous (ERAP1+/-) mice; a mouse with a phenotype likely more equivalent to what would be seen in human subjects, i.e. reduced, not absent, ERAP1. We observed that ERAP1+/- mice had 45% lower ERAP1 levels by western blot analyses in heart and kidney as compared to wild-type (WT) littermate control mice maintained on regular rodent chow (n= 10 of each type, p=0.029). We measured ANGII tissue levels by LC/MS and show increased levels in heart, kidney and aortas from ERAP1+/- as compared to WT control mice (P<0.05). On regular rodent chow, urinary 24 hr ALDO levels were increased in ERAP1+/- compared to WT mice (7.11 ±0.82 [WT, n=10] vs 9.92 ±0.88 ng/dL [ERAP1+/-, n=8], p=0.03) while plasma renin activity (PRA) were not significantly different between the two mouse types (65.3±3.2 [WT, n=10] vs 66.16±2.3 ng/ml*h [ERAP1+/-, n=8]). We also evaluated BP by tail cuff on mice maintained on regular rodent chow and showed increased systolic BP in ERAP1+/- as compared to WT mice, (122.8±0.8 [ERAP1, n=9] vs. 110.2±1.6 mmHg [WT, n=12], p=0.003). We then studied the effects of salt intake on BP in these mice. ERAP1+/- mice had increased salt sensitivity of BP, defined as systolic BP on high, 1.6% Na+ diet minus systolic BP on low, 0.03% Na+ diet, when compared to WT mice (SSBP: 8.5±2.3 [ERAP1, n=15] vs -0.2 ±1.6 mmHg [WT, n=15], p=0.0043). Similar results were obtained using continuous intraarterial BP monitoring by telemetry in freely moving mice (SSBP by telemetry: 6.8±1.2 [ERAP1, n=3] vs 0.4±0.7 mmHg [WT, n=2], p<0.001). We then studied renal hemodynamics using 2D and Color-Doppler imaging and showed that ERAP1+/- mice have increased peak-systolic velocity (PSV) and end-diastolic velocity (EDV) compared to WT mice on regular mouse chow (PSV: 412.6±38.6 [WT, n=4] vs 570.2±27.7 mm/s [ERAP1+/-, n=3] p=0.027; EDV: 127.9±9.8 [WT, n=4] vs 191.0±16.3 mm/s [ERAP1+/-, n=6], p=0.02). In conclusion, ERAP1 deficiency is associated with SSBP, likely secondary both to increased ALDO and altered renovascular function.

Inflammatory response and optimalisation of perioperative fluid administration during hyperthermic intraoperative intraperitoneal chemotherapy surgery.

Surgical cytoreduction and simultaneous hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis has a high incidence of postoperative complications. Inadequate intraoperative volume therapy is a known risk factor for the development of postoperative complications. Another possible risk factor is the inflammatory response due to surgery and HIPEC. The aim of this observational pilot study was to monitor fluid intake in the first 24 hours peri- and postoperative by using a non-invasive cardiac output indicator. Furthermore, we measured circulating cytokines and evaluated the possible relation of these changes of inflammatory response with the non-invasive monitored fluid management. Twenty-four patients undergoing cytoreductive surgery and HIPEC for peritoneal carcinomatosis were included. Patients were randomised into either a liberal fluid management group using intra-arterial blood pressure and central venous pressure measurement or a restrictive group by using intra-arterial blood pressure and central venous pressure measurement with FloTrac/Vigileo monitoring. Cytokines were measured with multiplex immunoassays. We found no difference in the amount of fluid administration in patients undergoing HIPEC surgery with FloTrac/Vigileo monitoring compared to standard care. Furthermore, there was no difference in mortality, ICU and hospital length of stay between both groups. A severe inflammatory response was seen in all patients after the HIPEC procedure with a rapid increase of interleukins and C-reactive protein (CRP). There was however no difference between our intervention and control group in the severity of this reaction. Finally, we found no relation between the severity of the inflammatory response and mortality, or a composite end-point of mortality and severe complications within 30 days postoperative. FloTrac/Vigileo monitoring does not lead to a more restrictive fluid administration and does not influence short-term clinical course in patients undergoing HIPEC surgery. The procedure itself leads to a severe inflammatory response, which is not affected by the use of FloTrac/Vigileo. Our data do not support the use of FloTrac/Vigileo monitoring in patients undergoing HIPEC surgery concerning fluid restrictive management.

Patterns of cardiovascular variability after long-term sino-aortic denervation in unanesthetized adult rats

Baroreflex dysfunction is a diffuse chronic condition that is expected to be followed by a profound loss of organization of BP and HR variability. Nevertheless, long-term effects of baroreflex withdrawal are still debated. Aim of our work was to study BP and HR changes long term after sino-aortic denervation (SAD). Inter-beat-interval (IBI) and intra-arterial BP were recorded beat-by-beat in 43 Wistar-Kyoto rats (Controls, n = 33; SAD rats, n = 10). Power spectra were calculated in controls and in SAD rats within three days and at seven months from denervation. Compared to controls, chronic SAD rats showed 1) similar mean BP (control vs SAD: 95 ± 16 vs 87 ± 22 mmHg) and IBI (171 ± 22 vs 181 ± 15 ms) values, 2) dramatically higher values of BP variance (12 ± 2 vs 64 ± 2 mmHg2, p < 0.01) and of ultra- (ULF) and very-low-frequency (VLF) BP oscillations, 3) dramatically higher values of IBI variability (24 ± 2 vs 71 ± 4 ms2, p < 0.01) and of ULF-IBI oscillations that were synchronized with BP oscillations. Chronic SAD rats reveal a marked change in the pattern of cardiovascular variability characterized by the appearance of synchronized slower oscillations of BP and HR. The cardiovascular system, therefore, retains a high level of organization despite the absence of a reflex control mechanism.

Intra-arterial analysis of the best calibration methods to estimate aortic blood pressure.

Estimation of aortic blood pressure (BP) requires peripheral BP waveform calibration. Mean arterial pressure (MAP)/DBP calibration is purported to estimate aortic BP more accurately than SBP/DBP calibration. However, this is based on inaccurate cuff calibration. Thus, direct comparisons of each calibration method using intra-arterial BP are required to confirm this, and was the aim of this study. Ascending aortic, brachial and radial artery intra-arterial BPs were measured among 107 patients (61.9 ± 10.0 years, 70% men) undergoing coronary angiography. Radial waveforms were calibrated with brachial SBP/DBP and brachial MAP/DBP to directly test the accuracy of estimated aortic SBP (derived using a commercial device) from each calibration compared with intra-arterial aortic SBP. Estimated aortic BP accuracy from aortic MAP/DBP, brachial and radial SBP/DBP calibrations of peripheral waveforms was also tested (six calibration methods in total; all using intra-arterial BP). Estimated aortic SBP from brachial MAP/DBP calibration of radial waveforms had a significantly smaller mean difference than from brachial SBP/DBP calibration (-0.7 ± 7.5 mmHg versus -6.9 ± 7.3 mmHg, P < 0.0001 for difference). Of the other calibration methods, estimated aortic SBP was most accurate from aortic MAP/DBP calibration of radial waveforms (-1.8 ± 5.0 mmHg, P = 0.00023). However, for all calibration methods, aortic-to-brachial artery and/or brachial-to-radial artery SBP amplification had a major influence on estimated aortic SBP. Brachial and aortic MAP/DBP were confirmed as the best calibration methods to estimate aortic SBP, but irrespective of calibration method, accuracy was significantly influenced by the level of SBP amplification. Thus, improved accuracy of estimated aortic SBP should be possible by closer consideration of SBP amplification or individual waveform characteristics that differ according to the level of SBP amplification.

Noninvasive Blood Pressure Monitor Designed for Patients With Heart Failure Supported with Continuous-Flow Left Ventricular Assist Devices.

The gold standard for noninvasive blood pressure (BP) measurement, the Doppler technique, does not provide systolic blood pressure (SBP) and diastolic blood pressure (DBP) and may limit therapy outcomes. To improve patient care, we tested specifically designed experimental BP (ExpBP) monitor and the Doppler technique by comparing noninvasive measures to the intraarterial (I-A) BP in 31 patients with end-stage heart failure (4 females) 2.6 ± 3.4 days post-LVAD implantation (20 HeartMate II and 11 HeartWare). Bland-Altman plots revealed that the ExpBP monitor overestimated mean arterial pressure (MAP) by 1.2 (4.8) mm Hg (mean difference [standard deviation]), whereas the Doppler by 6.7 (5.8) mm Hg. The ExpBP SBP was overestimated by 0.8 (6.1) mm Hg and DBP by 1.9 (5.3) mm Hg compared with the respective I-A pressures. Both techniques achieved similar measurement reliability. In the measurement "success rate" expressed as a frequency (percent) of readable BP values per measurement attempts, Doppler accomplished 100% vs. 97%, 97%, and 94% of successful detections of MAP, SBP, and DBP provided by the ExpBP monitor. The ExpBP monitor demonstrated higher accuracy in the MAP assessment than the Doppler in addition to providing SBP and DBP in majority of subjects. Improved BP control may help to mitigate related neurologic adverse event rates.

Royal Perth Hospital airway &amp; head and neck anesthesiology fellowship

Royal Perth Hospital airway &amp; head and neck anesthesiology fellowship

Alpha2B-Adrenergic Receptor Overexpression in the Brain Potentiate Air Pollution-induced Behavior and Blood Pressure Changes.

Fine ambient particulate matter (PM2.5) is able to induce sympathetic activation and inflammation in the brain. However, direct evidence demonstrating an essential role of sympathetic activation in PM2.5-associated disease progression is lacking. We assess the contribution of α2B-adrenergic receptor (Adra2b) in air pollution-associated hypertension and behavioral changes in this study. Wild-type mice and Adra2b-transgenic mice overexpressing Adra2b in the brain (Adra2bTg) were exposed to concentrated PM2.5 or filtered air for 3 months via a versatile aerosol concentrator exposure system. Mice were fed with a high salt diet (4.0% NaCl) for 1 week at week 11 of exposure to induce blood pressure elevation. Intra-arterial blood pressure was monitored by radio-telemetry and behavior changes were assessed by open field, light-dark, and prepulse inhibition tests. PM2.5 exposure increased Adra2b in the brain of wild-type mice. Adra2b overexpression enhanced the anxiety-like behavior and high salt diet-induced blood pressure elevation in response to air pollution but not filtered air exposure. Adra2b overexpression induced upregulation of inflammatory genes such as TLR2, TLR4, and IL-6 in the brain exposed to PM2.5. In addition, there were increased frequencies of activated effector T cells and increased expression of oxidative stress-related genes, such as SOD1, NQO1, Nrf2, and Gclm in Adra2bTg mice compared with wild-type mice. Our results provide new evidence of distinct behavioral changes consistent with anxiety and blood pressure elevation in response to high salt intake and air pollution exposure, highlighting the importance of centrally expressed Adra2b in the vulnerability to air pollution exposure.

Predicting Hemodynamic Shock from Thermal Images using Machine Learning

Proactive detection of hemodynamic shock can prevent organ failure and save lives. Thermal imaging is a non-invasive, non-contact modality to capture body surface temperature with the potential to reveal underlying perfusion disturbance in shock. In this study, we automate early detection and prediction of shock using machine learning upon thermal images obtained in a pediatric intensive care unit of a tertiary care hospital. 539 images were recorded out of which 253 had concomitant measurement of continuous intra-arterial blood pressure, the gold standard for shock monitoring. Histogram of oriented gradient features were used for machine learning based region-of-interest segmentation that achieved 96% agreement with a human expert. The segmented center-to-periphery difference along with pulse rate was used in longitudinal prediction of shock at 0, 3, 6 and 12 hours using a generalized linear mixed-effects model. The model achieved a mean area under the receiver operating characteristic curve of 75% at 0 hours (classification), 77% at 3 hours (prediction) and 69% at 12 hours (prediction) respectively. Since hemodynamic shock associated with critical illness and infectious epidemics such as Dengue is often fatal, our model demonstrates an affordable, non-invasive, non-contact and tele-diagnostic decision support system for its reliable detection and prediction.

Intra-arterial pulse wave analysis during thrombectomy for the assessment of collateral status - A feasibility study.

PurposeKnowledge of the collateralization of an occluded vessel is important for the risk-benefit analysis of difficult revascularization maneuvers during mechanical thrombectomy. If the territory behind a clot is well perfused, one could desist from performing a risky thrombectomy maneuver. The arterial pulse pressure curve may serve as an indicator for the collateralization of an occluded target vessel. We investigated the feasibility of arterial pulse measurements with a standard microcatheter.MethodsWe measured the intra-arterial blood pressure proximal and distal to the clot in 40 thrombectomy maneuvers in a porcine stroke model. We used a microcatheter (Trevo Pro 18, Stryker, Kalamazoo, CA, USA), a pressure transducer (MEMSCAP SP844), an AdInstruments Powerlab 16/35 workstation, and LabChart 8 Software (AdInstruments, Dunedin, New Zealand).ResultsMedian arterial blood pressure proximal and distal to the clot was 96.0 mmHg (IQR, 23.8 mmHg) and 47.5 mmHg (IQR, 43.5 mmHg), respectively (p < .001). The median difference between systolic maximum and diastolic minimum proximal and distal to the clot decreased significantly from 1.8 mmHg (IQR, 3.6 mmHg) to 0.0 mmHg (IQR, 0.5 mmHg) (p < .001). There was loss of the curve in 26 of 40 cases and loss of pressure in 23 of 40 cases (p = .008). There was no significant correlation between vessel diameter and either loss of the pulse pressure curve (p = .20) or overall pressure loss (p = .31).ConclusionIt is possible to measure the pulse pressure proximal and distal to the clot with a standard microcatheter used during mechanical thrombectomy.

A Meta-analysis to Determine the Validity of Taking Blood Pressure Using the Indirect Cuff Method.

The purpose of this meta-analysis was to compare the magnitude of systematic bias (mean difference) and random error (standard deviation of mean difference) between the cuff method of indirect blood pressure and directly measured intra-arterial pressure. Blood pressure is almost exclusively assessed using the indirect cuff method; however, numerous individual studies have questioned the validity relative to directly measured intra-arterial blood pressure. PubMed, SportsDiscus, and Scopus were searched through February 2018. Data were analyzed using a random effects model. A total of 62 studies met the inclusion criteria for quantitative analysis including 103 effect sizes for systolic and 114 effect sizes for diastolic blood pressure. Indirect measures of systolic blood pressure were underestimated (- 4.55 (95% CI = - 5.58 to - 3.53) mmHg), while diastolic blood pressure was overestimated (6.20 (95% CI = 5.09 to 7.31) mmHg). The random error (SD units) was 10.32 (95% CI = 9.29 to 11.36) for systolic and 7.92 (95% CI = 7.35 to 8.50) for diastolic blood pressure which corresponds to an estimation accuracy (95% confidence) of ± 20.2 mmHg for systolic blood pressure and ± 15.5 mmHg for diastolic blood pressure. These data indicate that it may be difficult to accurately estimate intra-arterial blood pressure using the cuff method. These results not only have implications for clinicians in diagnosing hypertension, but also may detail a potential underestimation of the association between blood pressure and numerous other health outcomes found in epidemiological studies.

Continuous spinal anaesthesia for caesarean section in a patient with peripartum cardiomyopathy.

Continuous spinal anaesthesia for caesarean section in a patient with peripartum cardiomyopathy.

Reservoir-excess pressure characteristics help identify people with high intra-arterial aortic systolic blood pressure

BackgroundHigh aortic blood pressure (BP) predicts clinical outcomes beyond peripheral BP. Aortic BP may differ according to level of systolic BP (SBP)-amplification but these differences cannot be identified using current non-invasive BP measurement methods. In this study, we sought to determine if high intra-arterial aortic BP could be detected via reservoir-excess pressure characteristics.MethodsStandard cuff BP, SphygmoCor-derived central BP (CBP), and intraarterial aortic and brachial waveforms were recorded in 160 participants (61 ±11 years, 68% male) during coronary angiography. SBP-amplification was defined as ≥5 mmHg increase in SBP across the aortic-to-brachial arteries, whereas no SBP-amplification was defined as 0.20 both). Aortic, but not brachial, reservoir pressure was significantly higher in participants with no SBP-amplification (2506 ± 662 versus 2239 ± 640 Pa/s, p = 0.011). This pattern was also observed for aortic excess pressure (718 ± 304 versus 624 ± 293 Pa/s, p = 0.049) and aortic diastolic rate constant (0.021 ± 0.08 versus 0.025 ± 0.09 s−1, p = 0.002). All differences remained after adjustment for age, sex and intra-arterial aortic SBP.ConclusionsReservoir-excess pressure characteristics help identify people with high intra-arterial aortic BP that are otherwise missed using cuff BP or SphygmoCor-derived CBP. Thus, analysis of BP waveforms using reservoir-excess pressure characteristics could be used to refine accuracy of BP measurement.

Accuracy of blood pressure monitoring devices: a critical need for improvement that could resolve discrepancy in hypertension guidelines.

Hypertension is the most significant modifiable risk factor for cardiovascular disease and contributes to the highest global burden of disease. Blood pressure (BP) measurement is among the most important of all medical tests, and it is critical for BP monitoring devices to be accurate. Comprehensive new evidence from meta-analyses clearly shows that many BP monitoring devices (including oscillometric machines and "gold standard" mercury auscultation) do not accurately represent the BP within the arteries at the upper arm (brachial) or central aorta. Particular variability in the accuracy of BP devices compared with intra-arterial BP has been demonstrated in the cuff BP range from prehypertension to grade I hypertension (systolic BP 120-159 to diastolic BP 80-99 mmHg). This is within the BP range that is most common among people worldwide and, thus almost certainly, feeding confusion around optimal hypertension guideline thresholds. At the individual level, inaccurate BP devices have major potential consequences for best practice patient management, where underestimation of true BP is a missed opportunity to lower cardiovascular risk (with therapeutics or lifestyle) and overestimation of true BP could lead to overmedication. Each problem leads to increased cost from preventable cardiovascular events and unnecessary medications. Altogether, there is a critical need to improve the accuracy standards of BP monitoring devices. In the meantime, out-of-office BP (24 h of ambulatory BP and/or home BP monitoring) or automated, unobserved in-office BP monitoring that takes the average of multiple readings using validated devices are the best available options to determine BP control.