Pressure Catheter Research Articles

Risk factor analysis of urinary tract infection by cefotaxime-resistant Escherichia coli and Klebsiella pneumoniae: a simple and effective analysis using the National Health Insurance Data Sharing Service

Background: This study aims to analyze the risk factors for urinary tract infection (UTI) by cefotaxime-resistant Escherichia coli or Klebsiella pneumoniae, using data from the National Health Insurance Data Sharing Service. Methods: A retrospective case-control study was conducted to analyze the risk factors during 11 years (2010–2020). Study groups were selected based on the laboratory data of the hospital, which comprised 3,638 and 877 cases of cefotaxime-resistant E. coli and K. pneumoniae, respectively. Controls comprised 8,994 and 1,573 cases of cefotaxime-nonresistant (intermediate or susceptible) E. coli and K. pneumoniae, respectively. Clinical and socioeconomical features were obtained from the National Health Insurance service data. Results: In a multivariate analysis of risk factors for UTI by cefotaxime-resistant E. coli, the odds ratio (OR) of the male sex was 1.335 (95% confidence interval, 1.204–1.480), age 0–9 years was 1.794 (1.468–2.191), chronic renal disease was 1.227 (1.062–1.417), and hemodialysis was 1.685 (1.255–2.262). Moreover, the ORs of L-tube, central venous pressure catheter, and Foley catheter use were 1.204 (1.047–1.385), 1.332 (1.156–1.534), and 1.473 (1.316–1.649), respectively; the OR of previous antimicrobial use was 1.103 (1.009–1.206) and that of healthcare facility use was 1.782 (1.576–2.014). In a multivariate analysis of risk factors for UTI by cefotaxime-resistant K. pneumoniae, OR of the male sex was 1.460 (1.199–1.778), liver disease was 1.295 (1.037–1.617), and hemodialysis was 2.046 (1.263–3.315). The ORs of L-tube and Foley catheter use were 2.329 (1.861–2.915) and 1.793 (1.431–2.246), respectively, and the OR of the healthcare facility use was 1.545 (1.161–2.056). Conclusion: In this study, the risk factors for UTI caused by cefotaxime-resistant E. coli or K. pneumoniae were analyzed based on the data of a specific healthcare facility linked to the National Health Insurance system. We suggest that it is a simple and effective way to elucidate risk factors of infections caused by major antimicrobial-resistant pathogens.

Non-invasive left ventricular pressure-volume loops from cardiovascular magnetic resonance imaging and brachial blood pressure: validation using pressure catheter measurements.

Left ventricular (LV) pressure-volume (PV) loops provide gold-standard physiological information but require invasive measurements of ventricular intracavity pressure, limiting clinical and research applications. A non-invasive method for the computation of PV loops from magnetic resonance imaging and brachial cuff blood pressure has recently been proposed. Here we evaluated the fidelity of the non-invasive PV algorithm against invasive LV pressures in humans. Four heart failure patients with EF < 35% and LV dyssynchrony underwent cardiovascular magnetic resonance (CMR) imaging and subsequent LV catheterization with sequential administration of two different intravenous metabolic substrate infusions (insulin/dextrose and lipid emulsion), producing eight datasets at different haemodynamic states. Pressure-volume loops were computed from CMR volumes combined with (i) a time-varying elastance function scaled to brachial blood pressure and temporally stretched to match volume data, or (ii) invasive pressures averaged from 19 to 30 sampled beats. Method comparison was conducted using linear regression and Bland-Altman analysis. Non-invasively derived PV loop parameters demonstrated high correlation and low bias when compared to invasive data for stroke work (R2 = 0.96, P < 0.0001, bias 4.6%), potential energy (R2 = 0.83, P = 0.001, bias 1.5%), end-systolic pressure-volume relationship (R2 = 0.89, P = 0.0004, bias 5.8%), ventricular efficiency (R2 = 0.98, P < 0.0001, bias 0.8%), arterial elastance (R2 = 0.88, P = 0.0006, bias -8.0%), mean external power (R2 = 0.92, P = 0.0002, bias 4.4%), and energy per ejected volume (R2 = 0.89, P = 0.0001, bias 3.7%). Variations in estimated end-diastolic pressure did not significantly affect results (P > 0.05 for all). Intraobserver analysis after one year demonstrated 0.9-3.4% bias for LV volumetry and 0.2-5.4% for PV loop-derived parameters. Pressure-volume loops can be precisely and accurately computed from CMR imaging and brachial cuff blood pressure in humans.

Non-contact quantification of aortic stenosis and mitral regurgitation using carotid waveforms from skin displacements.

Objective. Early diagnosis of heart problems is essential for improving patient prognosis.Approach. We created a non-contact imaging system that calculates the vessel-induced deformation of the skin to estimate the carotid artery pressure displacement waveforms. We present a clinical study of the system in patients (n= 27) with no underlying condition, aortic stenosis (AS), or mitral regurgitation (MR).Main results. Displacement waveforms were compared to aortic catheter pressures in the same patients. The morphologies of the pressure and displacement waveforms were found to be similar, and pulse wave analysis metrics, such as our modified reflection indices (RI) and waveform duration proportions, showed no significant differences. Compared with the control group, AS patients displayed a greater proportion of time to peak (p= 0.026 andp= 0.047 for catheter and displacement, respectively), whereas augmentation index (AIx)was greater for the displacement waveform only (p= 0.030). The modified RI for MR (p= 0.047 andp= 0.004 for catheter and displacement, respectively) was lower than in the controls. AS and MR were also significantly different for the proportion of time to peak (p= 0.018 for the catheter measurements), RI (p= 0.045 andp= 0.002 for the catheter and displacement, respectively), and AIx (p= 0.005 for the displacement waveform).Significance. These findings demonstrate the ability of our system to provide insights into cardiac conditions and support further development as a diagnostic/telehealth-based screening tool.

Intratendinous pressure of the Achilles tendon during exercise is related to the degree of tendon torsion.

Torsion of the Achilles tendon (AT) enhances tensile strength, but a high degree of torsion might also be a risk factor for Achilles tendinopathy, due to greater internal compression exerted during tensile loading. However, evidence supporting the grounds for this assumption is lacking. Hence, we aimed to investigate the impact of AT torsion type on intratendinous pressure. Eighteen human fresh frozen cadaveric legs were mounted in a testing rig and a miniature pressure catheter was placed through ultrasound-guided insertion in the midportion region of the AT. Intratendinous pressure was measured during a simulated straight-knee calf stretch and eccentric heel drop. The AT was then carefully dissected and classified into Type I (least), Type II (moderate), and Type III (extreme) torsion. Of the ATs examined, nine were found to have Type I torsion (50%), nine Type II (50%), and none Type III. It was found that the intratendinous pressure of the AT increased exponentially with ankle dorsiflexion during both exercises (p < 0.001) and that this increase was greater in ATs with Type II torsion than Type I torsion (p < 0.05). This study provides the first biomechanical data to support the hypothesis that in athletes with a high degree of torsion in the AT, the midportion area will experience more internal compression during exercise, for example, calf stretching and eccentric heel drops. Whether this phenomenon is also associated with an elevated risk for Achilles tendinopathy needs further prospective investigation.

ACE2 overexpression in corticotropin-releasing-hormone cells offers protection against pulmonary hypertension.

Pulmonary hypertension (PH), characterized by elevated pulmonary pressure and right heart failure, is a systemic disease involving inappropriate sympathetic activation and an impaired gut-brain-lung axis. Global overexpression of angiotensin converting enzyme 2 (ACE2), a cardiopulmonary protective enzyme of the renin-angiotensin system, attenuates PH induced by chronic hypoxia. Neurons within the paraventricular nucleus of the hypothalamus (PVN) that synthesize corticotropin-releasing hormone (CRH) are activated by stressors, like hypoxia, and this activation augments sympathetic outflow to cardiovascular tissues. These data coupled with our observations that ACE2 overexpression in CRH cells (CRH-ACE2KI mice) decreases anxiety-like behavior via suppression of hypothalamic-pituitary-adrenal (HPA) axis activity by decreasing CRH synthesis, led us to hypothesize that selective ACE2 overexpression in CRH neurons would protect against hypoxia-induced PH. CRH-ACE2KI and WT male and female mice were exposed to chronic hypoxia (10%O2) or normoxia (21%O2) for 4 weeks in a ventilated chamber with continuous monitoring of oxygen and carbon dioxide concentrations (n = 7-10/group). Pulmonary hemodynamics were measured with Millar pressure catheters then tissues were collected for histological analyses. Chronic hypoxia induced a significant increase (36.4%) in right ventricular (RV) systolic pressure (RVSP) in WT mice, which was not observed in CRH-ACE2KI mice. No significant differences in RVSP were observed between male and female mice in any of the groups. Overexpression of ACE2 in CRH cells was protective against hypoxia-induced PH. Since the majority of expression of CRH is in brain nuclei such as paraventricular nucleus of the hypothalamus (PVN) and/or central nucleus of the amygdala (CeA) these data indicate that the protective effects of ACE2 are, at least in part, centrally mediated. This contributes to the systemic nature of PH disease and that CRH neurons may play an important role in PH.

Pilot Study on the Influence of Incentive Spirometry on Percutaneous Image-Guided Intra-Abdominal Drainage Catheter Pressure: A Potential Method to Enhance Drainage.

To report the evaluation of incentive spirometry (IS)-induced pressure changes in intra-abdominal drainage catheters and consider its use for maintaining catheter patency and enhancing drainage. Prospective study of patients with indwelling intra-abdominal drainage catheters for abdominal fluid collections who had their intra-abdominal pressures measured while performing incentive spirometry. Patients were instructed in the use of an incentive spirometer. Within a week after initial drainage, pressure changes with IS were evaluated three times at 1500 cc and three times at maximum inspiratory effort. Intra-abdominal pressure (IAP) was measured using a pressure monitor connected to the drainage catheter. Twenty patients (men, 12; women, 8). Fluid collection locations were pelvis, Right-upper quadrant (RUQ), Left-upper quadrant (LUQ), Left-lower quadrant (LLQ), and Right-lower quadrant (RLQ). A total of 16 of 20 patients showed an elevation of IAP with IS. At 1500 cc, the pressure increased by an average of 41.24 mmH2O. At maximal inspiratory effort, the pressure increased by an average of 48.26 mmH2O. Pressure increase was greater in upper abdomen catheters. Four patients with lower abdominal and pelvic collections showed minimal pressure changes with IS. IS increases IAP and fluid flow through abdominal drainage catheters. Future studies are warranted to determine whether the use of IS enhances catheter performance and facilitates drainage via its effect on IAP.

Dynamic asymmetry in cerebrospinal fluid pressure: An indicator of regional differences in compliance.

Dural compliance influences the shape and magnitude of the cerebrospinal fluid (CSF) pulsations. In humans, cranial compliance is approximately 2× greater than spinal compliance; the differential has been attributed to the associated vasculature. In alligators, the spinal cord is surrounded by a large venous sinus, which suggests that the spinal compartment may have higher compliance than is found in mammals. Pressure catheters were surgically implanted into the cranial and spinal subdural spaces of eight subadult American alligators (Alligator mississippiensis). The CSF was propelled through the subdural space by orthostatic gradients and rapid changes in linear acceleration. CSF pressure recordings taken from the cranial compartment were consistently, and significantly, larger than those taken from the spinal compartment. After the myodural bridge of Alligator was surgically released, the asymmetry in CSF pressure was decreased. Unlike the situation in humans, the spinal compartment of Alligator has greater compliance than the cranial compartment, presumably due to the presence of the large spinal venous sinus surrounding the dura. The change in CSF pressures after myodural surgical release supports the hypothesis that the myodural bridge functions, at least in part, to modulate dural compliance and the exchange of CSF between the cranial and spinal compartments.

0427 Airway Pressures Define Collapsibility of Specific Pharyngeal Sites of Obstruction during Drug-induced Sleep Endoscopy

Abstract Introduction Obstructive sleep apnea (OSA) is characterized by repetitive episodes of pharyngeal obstruction at one or more collapse sites. Multilevel collapse is a negative predictive factor for PAP-alternative surgical treatments. Pharyngeal manometry during drug-induced sleep endoscopy (DISE) permits an objective evaluation of anatomical obstruction sites and mechanisms, and may play a role in patient selection for PAP alternative therapies. We hypothesized that patients with multilevel collapse would have primary velopharyngeal collapse and secondary, downstream sites. Methods This prospective cohort of twenty consecutive patients with diagnosed OSA underwent DISE with nasal airflow monitoring and pharyngeal manometry. Two pressure catheters were placed at the (1) distal margin of the soft palate (Pus) and (2) retroepiglottic space (Pds). We sought to delineate site(s) of collapse by evaluating dissociations in airflow and air pressure during inspiratory flow limitation and/or complete obstruction. The primary site of collapse was defined by the initial segment at which inspiratory airflow and pressure dissociated (the critical pressure, Pcrit). Secondary site(s) were defined as the pressure at which the Pus and/or Pds signals subsequently dissociated (beyond the initial point of maximal flow). Results Twenty-one patients were evaluated of which signal quality and catheter placement in twenty were sufficient for analysis. Participants were elderly (58.3±14.3yrs, mean±SD), overweight (BMI 28.7±2. kg/m2), and had moderate-severe OSA (AHI 28.2±14.2 events/hour). Six patients had a single site of collapse, of which one was naso-palatal (Pcrit -2.6cmH2O) and five were infra-palatal (mean Pcrit -1.3cmH2O). In the patients with multilevel collapse (N=14), all had primary naso-palatal collapse (mean Pcrit 0.17±2.0cmH2O) and secondary infra-palatal sites of collapse (mean Pcrit -11.7±5.8cmH2O). Pcrit differed between the primary and secondary site by 11.9±6.5cmH2O (p&amp;lt; 0.01). Conclusion These findings suggest that single-site pharyngeal collapse is usually infra-palatal. In contrast, multilevel collapse is primarily due to velopharyngeal collapse with varying degrees of instability in downstream pharyngeal segments. When secondary infra-palatal sites readily collapse with minimal additional respiratory effort, laxity of the tongue and/or lateral walls may be strongly implicated in the pathogenesis of pharyngeal obstruction. Future studies can utilize pharyngomanometry to further target specific pharyngeal structures for OSA therapy. Support (if any) National Institutes of Health 1R01HL144859 (PIs: Schwartz, Dedhia)

Differential angiogenic response contributes to sexual dimorphism in right ventricular adaptation in male and female Fischer CDF rats subjected to pulmonary artery banding model

Background: Female sex has been associated with better right ventricular (RV) adaptation and survival in patients with elevated RV afterload; however, the mechanisms underlying these differences remain unclear. Therefore, we studied the mechanisms underlying sex differences in RV remodeling and development of RHF using the rat pulmonary artery banding (PAB) model. Methods: Adult male and female Fischer CDF rats were subjected to PAB or sham surgery and echocardiography was performed at 1- or 2-weeks post-PAB to evaluate RV structure and function. RV systolic pressure (RVSP) was measured using a pressure catheter and Fulton Index (RV/ left ventricle + septum) was measured to evaluate RV hypertrophy (RVH). To explore the mechanisms, a focused PCR array was performed to assess the expression of angiogenic genes in the RV of male and female rats subjected to sham or PAB procedure. RV endothelial cells (RVECs) were isolated from Fischer CDF rats and effects of female sex hormones on angiogenic ability of RVECs was assessed using Matrigel network formation assay. We also assessed the role of sphingosine kinase-1 (Sphk1) inhibitor, PF-543, in mediating the effects of female sex hormones on angiogenic potential of RVECs. Results: At 1- and 2-week post-PAB, RVSP and RVH were significantly elevated in PAB rats compared to control rats; however, no differences were observed between male and female rats. Cardiomyocyte surface area (330 vs 234 mm2, p&lt;0.05) and fibrosis (6.96 vs 4.58%, p&lt;0.05) were both significantly higher in male compared to female rats. RV end-diastolic diameter was also increased in male rats compared to female rats (3.33 vs 2.05 mm; p&lt;0.05). On the contrary, RV function was preserved in female rats as indicated by higher cardiac index and fractional area change compared to male rats. Up-regulation of angiogenic genes, including Sphk1, was observed in the RV of female rats compared to male rats at 2 weeks post-PAB. Estradiol treatment increased network forming ability of RVEC isolated from Fischer CDF rats and this effect was inhibited by PF-543. Conclusions: Female Fischer CDF rats develop adaptive RV remodeling in response to PAB compared to mal-adaptive RV remodeling in male rats. Moreover, the better RV adaptation in female rats involves increased RV angiogenesis and these effect may be mediated through Sphk1. Research Nova Scotia, Dalhousie University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

PO-02-041 USE OF FLUOROSCOPY AND RADIATION EXPOSURE DURING AF ABLATION: A SINGLE-CENTRE 10-YEAR EXPERIENCE

The number of patients referred for atrial fibrillation (AF) ablation has been increasing over the years. Currently, technological improvements make AF ablation a relatively fast and predictable procedure. Notwithstanding, the technique still relies on fluoroscopy, and its effects remain a point of concern for both patients and health care professionals. The aim of this study was to assess the impact of technological advances on the use of fluoroscopy in AF ablation, and to analyze the radiation dose used in contemporary procedures. Single-center prospective registry including patients submitted to first radiofrequency point-by-point pulmonary vein isolation (PVI) using CARTO® mapping system since 2013 to November 2022. Patients with additional targets other than PVI, and those in whom single-shot techniques were employed, were excluded (n = 375). Fluoroscopy duration and absorbed (mGy) and effective dose of radiation (mSv) were assessed for each patient. Effective radiation dose was estimated by multiplying dose-area product (Gy.cm2) by a conversion coefficient of 0.15 mSv(Gy.cm2)–1. A total of 1027 patients (mean age 61 ± 11 years, 61.7% male, 81.4% with paroxysmal AF) were included. Overall, median fluoroscopy duration was 8.5 minutes (IQR 5.4-14.4). Over the last decade, there was a significant decrease of fluoroscopy times (from 20.7 [IQR 13.6-25.4] to 6.4 [IQR 4.5-10.7] minutes, p for trend <0.001). The reduction of X-ray duration was more expressive from 2014 and 2015, corresponding to the introduction of pressure catheters (STSF®) and image integration in electroanatomic mapping, respectively (Figure 1). There was also a decrease on radiation dose over the years. In 2022, median absorbed radiation per procedure was 119mGy (IQR 69-223), and median estimated effective radiation dosage was 0.94mSv (IQR 0.68-3.95). Over the last decade there was a significant reduction in fluoroscopy use during AF ablation, associated with the introduction of newer technologies. PVI is currently a very low radiation exposure procedure, comparable to coronary calcium scoring.

Beat-by-beat volume calibration refines pressure-volume derived indices of left ventricular function in the rat

Objective: Cardiac pressure-volume studies have advanced much of our understanding of mammalian cardiovascular physiology. Using admittance or conductance technology, the advantage of this technology over other methods to assess cardiovascular function is the ability to derive beat-by-beat pressure-volume loops and generate estimations of myocardial work (stroke work), as well as load-independent systolic (i.e., contractility) and diastolic (i.e., compliance) function from a caval occlusion. While these catheters are capable of extremely accurate recordings of cardiac pressure, volume measurement relies on a series of calibration steps that are oft-performed in isolation or at discrete timepoints. We propose a novel method that enables the refinement of ventricular volume measurement by enabling a beat-by-beat calibration of stroke volume (SV) at baseline and, most importantly, during caval occlusion where both the shape and characteristics of the ventricle are dynamically changing. Hypothesis: We hypothesised that beat-by-beat calibration of SV has a significant effect on PV-catheter derived indices of left ventricle (LV) function. Methodology: Data were collected from 10 rodents that were intubated, ventilated, and urethane anesthetized. We placed an admittance pressure-volume catheter (1.6F Scisense, Transonic Systems, Inc.) into the LV via an apical approach following thoracotomy, a perivascular flow probe (Transonic Systems, Inc.) was placed around the ascending aorta, a blood pressure catheter in the iliac artery, femoral venous lines for fluid/drug infusions, and an arterial line for blood gas analysis. We then assessed baseline and load-independent systolic function using the admittance catheter with and without beat-by-beat volume corrections obtained by integration of the perivascular flow data. Results: Firstly, we confirmed that the standard metrics of load-independent systolic function were increased in response to dobutamine (β1 agonist) and reduced in response to esmolol (β1 blocker). We then found that beat-by-beat volume correction from the perivascular flow probe increased baseline measures of SV and stroke work (SW). Comparing indices of load-independent systolic function calculated from corrected vs. uncorrected values of SV and SW, we found that beat-by-beat volume correction resulted in no significant change in d P/dt max - V ed (P=0.339) but a significant increase in PRSW (from 116±18 to 129±20 mmHg, P=0.020). Conclusions: Standard approaches to PV studies are able to accurately discern changes in contractile state. However, beat-by-beat calibration of the volume signal improves the absolute determination of volume indices and therefore influences derived measures of contractility. This research was funded by an NSERC Alliance grant to CRW and Mitacs Accelerate Postdoctoral Fellowship to OHW. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Intra-renal pressures during warm arterial and venous ischemia-reperfusion in rats

Red blood cell (RBC) trapping presents as the expansion- and obstruction of-, the outer-medullary capillaries of the kidney with tightly packed RBCs. RBC trapping has been shown to contribute to kidney injury and glomerular filtration rate decline, however, the mechanisms mediating RBC trapping remain unclear. It has previously been proposed that swelling of tubular cells during warm-ischemia initiates RBC trapping by increasing intra-renal pressure. This increase in pressure is thought to compresses the vasa recta capillaries that drain the renal medulla, initiating RBC trapping in the medullary circulation during reperfusion. In the current study we tested the hypothesis that ‘Intra-renal pressure is increased during warm ischemia-reperfusion’. We tested our hypothesis using young male Wistar-Kyoto rats (n=6). We examined pressure changes in the left kidney during ischemia-reperfusion from warm arterial (n=3) and venous (n=3) clamping using micro-serrefines. Rats were anesthetized with isoflurane (2-5%), a midline abdominal incision performed and the left artery and vein isolated. The left kidney was then cleared of connective tissue and placed in a kidney-cup to prevent movement. Intra-renal pressure was measured using a Millar micro-tip catheter pressure transducer which was inserted into the kidney outer-medulla. Intra-renal pressure was recorded during baseline and following 45 minutes of ischemia and 1 hour of reperfusion. Body temperature was maintained throughout the study using a servo-controlled heating table and heat lamp. At the end of the study, the left kidney was harvested and correct catheter placement confirmed. The kidneys were then fixed for later histological analysis. Data were compared using 2-way RM ANOVA (Graphpad Prism).Arterial clamping significantly increased intra-renal pressure (p&lt;0.001). Following arterial clamping, intra-renal pressure rapidly increased reaching a peak of ~30mmHg above baseline after ~6 minutes. Intra-renal pressure then fell slightly averaging 17±3mmHg above baseline over the clamp period. Upon release of the arterial clamp, intrarenal pressure fell to below baseline levels within 270 seconds. Following clamping of the renal vein, intrarenal pressure increased, reaching a peak of 28mmHg above baseline. The increase in average intrarenal pressure across the clamp period was significantly greater with venous compared to arterial clamping (p&lt;0.001), averaging 25±1mmHg. Similar to arterial clamping, intra-renal pressure rapidly fell to baseline levels following removal of the venous clamp.Our data indicate that both arterial and venous clamping increase intra-renal pressure during the clamp/ischemic period. As intra-renal pressure rapidly returns to baseline following removal of the clamp, however, compression of the venous vessels that drain the renal medulla by high intra-renal pressures is unlikely to mediate RBC trapping during reperfusion. NIH NIDDK ISAC 21AU4231, NIH NHLBI P01 HL134604 and an American Heart Association Transformational Project Award 970585 to P.O. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Use of External Uterine Electromyography Across Stage I Labor.

Highly sensitive, external uterine electromyography (EMG) measures myometrial electrical activity and is noninvasive compared with the clinical intrauterine pressure catheter. Most experimental studies have measured EMG in 30-minute epochs, limiting the utility of this instrumentation in intrapartum clinical practice. To test proof of concept, surface uterine EMG contraction activity was continuously collected throughout the first stage of labor from healthy women at term gestation with (n = 3) and without (n = 1) epidural or combined spinal-epidural analgesia for a maximal length of 11 hours and 24 minutes. EMG activity was recorded concurrently with tocodynamometer (toco) signals, using a pair of electrodes on the left and right sides of the maternal umbilicus with grounds attached to both hips of the reclining woman in labor. The preamplifier cutoff frequency settings were appropriate to monitor smooth muscle contraction in labor, with the analog high-pass filter set at 0.05 Hz and the low-pass filter at 1.50 Hz. Signals were sampled at 100 Hz, transmitted to a computer, and visualized by Chart 4.2 software. EMG data from epochs at baseline, during the pre-epidural fluid bolus and at the 60-minute post-epidural test dose, and at 3, 5, 6, and 8 cm dilatation were analyzed for burst power spectrum peak frequency (Hz), burst power spectrum amplitude (mV2 ), and burst duration (seconds). Uterine EMG contractile bursts were preceded and followed by a stable baseline and coincided with toco contractions. Movement artifacts were negligible, and large movement artifacts were easily distinguishable. The EMG bursts and toco contractions remained clearly identifiable, even when one woman without epidural analgesia stood beside the bed laboring for approximately 10 minutes. Burst spectral components fell within the expected 0.34-to-1.00 Hz range for term labor. High-quality data demonstrate that EMG instrumentation effectively and accurately measures uterine contraction parameters across the first stage of term labor.

A Systematic Review of Methods Used to Determine the Work of Breathing during Exercise.

Measurement of the work of breathing (Wb) during exercise provides useful insights into the energetics and mechanics of the respiratory muscles across a wide range of minute ventilations. The methods and analytical procedures used to calculate the Wb during exercise have yet to be critically appraised in the literature. The aim of this systematic review was to evaluate the quality of methods used to measure the Wb during exercise in the available literature. We conducted an extensive search of 3 databases for studies that measured the Wb during exercise in adult humans. Data were extracted on participant characteristics, flow/volume and pressure devices, oesophageal pressure (Poes) catheters, and methods of Wb analysis. A total of 120 articles were included. Flow/volume sensors used were primarily pneumotachographs (n = 85, 70.8%), whereas the most common pressure transducer was of the variable reluctance type (n = 63, 52.5%). Oesophageal pressure was frequently obtained via balloon-tipped catheters (n = 114, 95.0%). Few studies mentioned calibration, frequency responses and dynamic compensation of their measurement devices. The most popular method of measuring the Wb was pressure-volume integration (n = 51, 42.5%), followed by the modified Campbell (n = 28, 23.3%) and Dean & Visscher diagrams (n = 26, 21.7%). Over one-third of studies did not report the methods used to process their pressure-volume data, and the majority (60.8%) of studies used the incorrect Wb units and/or failed to discuss the limitations of their Wb measurements. The findings of this systematic review highlight the need for the development of a standardized approach for measuring Wb which is informative, practical, and accessible for future researchers.

A handsewn pericardial valved pulmonary conduit: pulsatile flow loop in vitro and acute porcine in vivo evaluation.

Right ventricle to pulmonary artery anatomic discontinuity is common in complex congenital heart malformations. Handsewn conduits are a practised method of repair. In a proof-of-concept study, we evaluated pulmonary valve replacement with a handsewn pericardial valved pulmonary conduit in vitro and in vivo. A pulsatile flow-loop model (in vitro) and an acute 60-kg porcine model (in vivo) were used. With echocardiography and pressure catheters, baseline geometry and fluid dynamics were measured. The pulmonary valve was replaced with a handsewn glutaraldehyde-treated pericardial valved pulmonary conduit corresponding to a 21-mm prosthetic valve, after which geometric measurements and fluid dynamics were reassessed. In vitro, 15 pulmonary trunks at 4 l/min and 13 trunks at 7 l/min, and in vivo, 11 animals were investigated. The valved pulmonary conduit was straightforward to produce at the operating table and easy to suture in place. All valves were clinically sufficient in vitro and in vivo. The mean transvalvular pressure gradient in the native valve and the conduit was 8 mmHg [standard deviation (SD): 2] and 7 mmHg (SD: 2) at 4 l/min in vitro, 19 mmHg (SD: 3) and 17 mmHg (SD: 4) at 7 l/min in vitro and 3 mmHg (SD: 2) and 6 mmHg (SD: 3) in vivo. Our proof-of-concept demonstrates no early evidence of structural damage to the conduit, and the fluid dynamic data were acceptable. The handsewn conduit can be produced at the operating table.

PD14-11 PERCUTANEOUS URETHRAL SPHINCTER STIMULATION: SWINE MODEL FOR FEASIBILITY OF USE IN STRESS URINARY INCONTINENCE

You have accessJournal of UrologyCME1 Apr 2023PD14-11 PERCUTANEOUS URETHRAL SPHINCTER STIMULATION: SWINE MODEL FOR FEASIBILITY OF USE IN STRESS URINARY INCONTINENCE Kyle Waisanen, Tyler Maiers, Peter Natalzia, and Teresa Danforth Kyle WaisanenKyle Waisanen More articles by this author , Tyler MaiersTyler Maiers More articles by this author , Peter NatalziaPeter Natalzia More articles by this author , and Teresa DanforthTeresa Danforth More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003261.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Current treatment modalities for stress urinary incontinence (SUI) include pelvic floor physical therapy, urethral bulking agents, and urethral sling support. We aim to assess direct electrical external urethral sphincter stimulation as a means for treating SUI patients with intrinsic sphincter deficiency. The objective of this study was to assess the feasibility of percutaneous external urethral sphincter access and urethral pressure profiles associated with direct electric sphincteric stimulation. METHODS: An IACUC-approved swine model study was performed under general anesthesia. The urinary bladder was accessed by open cystotomy for placement of antegrade 7F urethral pressure catheter. Stimulation leads were deployed into the external urethral sphincter under transvaginal ultrasound guidance and antegrade urethroscopy was performed to confirm urethral integrity. Leads were then stimulated with serial increases in amplitude from an external pulse generator from 0.1 mA to 3.6 mA with pressure monitoring of the external urethral sphincter. RESULTS: Three swine subjects were utilized in the study. All subjects underwent successful percutaneous insertion of stimulation leads into the EUS without urethral violation. External urethral sphincter pressures recorded with electric stimulation amplitudes of 0 mA, 1.8 mA, and 3.6 mA were found to exhibit increased urethral pressures of 6-10 cm H2O, 16-20 cm H2O, and 31-36 cm H2O, respectfully. EMG capture was achieved in each subject with a corresponding increase in EMG activity with pulse generator amplitude increase represented in the urodynamic strip from subject #2 (Figure 1). CONCLUSIONS: Direct external urethral sphincter stimulation with increased urethral closure pressures is achievable by an ultrasound-guided percutaneous approach. Further studies are required to assess long-term effects and success of the stimulation in SUI modeled subjects with promising results seen in this preliminary proof-of-concept study. Source of Funding: Lent Foundation, University at Buffalo © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e416 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kyle Waisanen More articles by this author Tyler Maiers More articles by this author Peter Natalzia More articles by this author Teresa Danforth More articles by this author Expand All Advertisement PDF downloadLoading ...

Evaluation of transcranial Doppler use in patients with acute liver failure listed for emergency liver transplantation.

Acute liver failure (ALF) is characterized by hepatic encephalopathy (HE) often due to intracranial hypertension (ICH). The risk/benefit-balance of intraparenchymal pressure catheter monitoring is controversial during ALF. Perform an evaluation of transcranial Doppler (TCD) use in patients with ALF listed for emergency liver transplantation. Single center retrospective cohort study including all patients registered on high emergency LT list between 2012 and 2018. All TCD measurements performed during ICU stay after listing and after LT (when performed) were recorded. TCD was considered abnormal when pulsatility index (PI) was >1.2. Among 106 patients with ALF, forty-seven (44%) had a TCD while on list. They had more severe liver and extrahepatic organ failure. When performed, TCD was abnormal in 51% of patients. These patients more frequently developed ICH events (45% vs. 13%, p=.02) and more frequently required increase in sedative drugs and vasopressors. While 22% of patients with normal TCD spontaneously survived, all of those with abnormal TCD died or were transplanted (p=.02). All transplanted patients who had abnormal exams normalized their TCD within 2 (1-2)days after LT. TCD may be a useful non-invasive tool for ICH detection and management, then guide sedation withdrawal.

The incidence of spontaneous arrhythmias in telemetered beagle dogs, Göttingen Minipigs and Cynomolgus non-human primates: A HESI consortium retrospective analysis

IntroductionCharacterization of the incidence of spontaneous arrhythmias to identify possible drug-related effects is often an important part of the analysis in safety pharmacology studies using telemetry. MethodsA retrospective analysis in non-clinical species with and without telemetry transmitters was conducted. Electrocardiograms (24 h) from male and female beagle dogs (n = 131), Göttingen minipigs (n = 108) and cynomolgus non-human primates (NHP; n = 78) were analyzed. ResultsVentricular tachycardia (VT) was observed in 3% of the dogs but was absent in minipigs and NHPs. Ventricular fibrillation (VF) was not observed in the 3 species. Ventricular premature beats (VPBs) were more frequent during daytime and atrioventricular blocks (AVBs) were more frequent at night in all species. A limited number of animals exhibited a high arrhythmia frequency and there was no correlation between animals with higher frequency of an arrhythmia type and the frequency of other arrythmias in the same animals. Clinical chemistry or hematology parameters were not different with or without telemetry devices. NHP with a transmural left ventricular pressure (LVP) catheter exhibited a greater incidence of VPBs and PJCs compared to telemetry animals without LVP. DiscussionAll species were similar with regards to the frequency of ventricular ectopic beats (26–46%) while the dog seemed to have more frequent junctional complexes and AVB compared to NHP and minipigs. Arrhythmia screening may be considered during pre-study evaluations, to exclude animals with abnormally high arrhythmia incidence.

Diagnostic accuracy of cardiovascular magnetic resonance strain analysis and atrial size to identify heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) continues to be a diagnostic challenge. Cardiac magnetic resonance atrial measurement, feature tracking (CMR-FT), tagging has long been suggested to diagnose HFpEF and potentially complement echocardiography especially when echocardiography is indeterminate. Data supporting the use of CMR atrial measurements, CMR-FT or tagging, are absent. Our aim is to conduct a prospective case-control study assessing the diagnostic accuracy of CMR atrial volume/area, CMR-FT, and tagging to diagnose HFpEF amongst patients suspected of having HFpEF. One hundred and twenty-one suspected HFpEF patients were prospectively recruited from four centres. Patients underwent echocardiography, CMR, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements within 24 h to diagnose HFpEF. Patients without HFpEF diagnosis underwent catheter pressure measurements or stress echocardiography to confirm HFpEF or non-HFpEF. Area under the curve (AUC) was determined by comparing HFpEF with non-HFpEF patients. Fifty-three HFpEF (median age 78 years, interquartile range 74-82 years) and thirty-eight non-HFpEF (median age 70 years, interquartile range 64-76 years) were recruited. Cardiac magnetic resonance left atrial (LA) reservoir strain (ResS), LA area index (LAAi), and LA volume index (LAVi) had the highest diagnostic accuracy (AUCs 0.803, 0.815, and 0.776, respectively). Left atrial ResS, LAAi, and LAVi had significantly better diagnostic accuracy than CMR-FT left ventricle (LV)/right ventricle (RV) parameters and tagging (P < 0.01). Tagging circumferential and radial strain had poor diagnostic accuracy (AUC 0.644 and 0.541, respectively). Cardiac magnetic resonance LA ResS, LAAi, and LAVi have the highest diagnostic accuracy to identify HFpEF patients from non-HFpEF patients amongst clinically suspected HFpEF patients. Cardiac magnetic resonance feature tracking LV/RV parameters and tagging had low diagnostic accuracy to diagnose HFpEF.

Association between Elevated Intrauterine Resting Tone during Labor and Neonatal Morbidity.

Internal contraction monitoring provides a quantitative assessment of intrauterine resting tone. During the course of labor, elevated intrauterine resting tone may be identified. We hypothesized that elevated intrauterine resting tone could lead to compression of the spiral arteries, thus limiting uterine blood flow and resulting in neonatal compromise. Therefore, our objective was to assess the association between elevated resting tone during labor and neonatal morbidity. This was a secondary analysis of a prospective cohort study of singleton deliveries at ≥37 weeks of gestation. Patients with ruptured membranes and an intrauterine pressure catheter in place for at least 30 minutes prior to delivery were included. Intrauterine resting tone was calculated as the average baseline pressure between contractions during the 30 minutes prior to delivery. The study group had elevated intrauterine resting tone, defined as intrauterine resting tone ≥75th percentile (≥12.3 mm Hg). Primary outcome was composite neonatal morbidity: hypoxic-ischemic encephalopathy, hypothermia treatment, intubation, seizures, umbilical arterial pH ≤7.1, oxygen requirement, or death. Secondary outcomes included umbilical artery pH <7.2, lactate ≥4 mmol/L, and rates of neonatal intensive care unit admission. Of the 8,580 patients in the cohort, 2,210 (25.8%) met the inclusion criteria. The median intrauterine resting tone was 9.7 mm Hg (interquartile range: 7.3-12.3 mm Hg). Elevated resting tone was associated with a shorter median duration of the first stage of labor (10.0 vs. 11.0 hours, p < 0.01) and lower rates of labor induction and oxytocin augmentation (p < 0.01). Neonatal composite morbidity was higher among patients with elevated intrauterine resting tone (5.1 vs. 2.9%, p = 0.01). After adjusting for chorioamnionitis and amnioinfusion, elevated intrauterine resting tone was associated with increased risk of neonatal morbidity (adjusted odds ratio: 1.70, 95% confidence interval: 1.06-2.74). Our findings suggest that elevated intrauterine resting tone is associated with increased risk of neonatal composite morbidity. · Higher intrauterine resting tone is associated with increased risk of neonatal morbidity.. · Elevated intrauterine tone can negatively impact umbilical artery pH and lactate levels.. · If elevated intrauterine pressure is noted, we recommend close monitoring of fetal status..