Artery Catheter Research Articles

Trajectory pattern of serially measured acute kidney injury biomarkers in critically ill patients: a prospective observational study

BackgroundThe clinical value of the trajectory of temporal changes in acute kidney injury (AKI) biomarkers has not been well established among intensive care unit (ICU) patients.MethodsThis is a single-center, prospective observational study, performed at a mixed ICU in a teaching medical institute in Tokyo, Japan. Adult ICU patients with an arterial line and urethral catheter were enrolled from September 2014 to March 2015. Patients who stayed in the ICU for less than 48 h and patients with known end-stage renal disease were excluded from the study. Blood and urine samples were collected for measurement of AKI biomarkers at 0, 12, 24, and 48 h after ICU admission. The primary outcome was major adverse kidney events (MAKE) at discharge, defined as a composite of death, dialysis dependency, and persistent loss of kidney function (≥ 25% decline in eGFR).ResultsThe study included 156 patients. Serum creatinine-based estimated glomerular filtration rate (eGFR), plasma neutrophil gelatinase-associated lipocalin (NGAL), and urinary liver-type fatty acid-binding protein (uL-FABP) were serially measured and each variable was classified into three groups based on group-based trajectory modeling analysis. While the trajectory curves moved parallel to each other (i.e., “low,” “middle,” and “high”) for eGFR and plasma NGAL, the uL-FABP curves showed distinct trajectory patterns and moved in different directions (“low and constant,” “high and exponential decrease,” and “high and exponential increase”). These trajectory patterns were significantly associated with MAKE. MAKE occurred in 16 (18%), 16 (40%), and 9 (100%) patients in the “low and constant,” “high and exponential decrease,” and “high and exponential increase” groups, respectively, based on uL-FABP levels (p-value < 0.001). The initial value and the 12-h change in uL-FABP were both significantly associated with MAKE, even after adjusting for eGFR [Odds ratio (95% confidence interval): 1.45 (1.17–1.83) and 1.43 (1.12–1.88) for increase of initial value and 12-h change of log-transformed uL-FABP by 1 point, respectively].ConclusionsTrajectory pattern of serially measured urinary L-FABP was significantly associated with MAKE in ICU patients.

Is Arterial Cannulation Inevitable for Acute Type A Aortic Dissection Repair?

Is Arterial Cannulation Inevitable for Acute Type A Aortic Dissection Repair?

Performance of a Wearable Ring in Controlled Hypoxia: A Prospective Observational Study.

Over recent years, technological advances in wearables have allowed for continuous home monitoring of heart rate and oxygen saturation. These devices have primarily been used for sports and general wellness and may not be suitable for medical decision-making, especially in saturations below 90% and in patients with dark skin color. Wearable clinical-grade saturation of peripheral oxygen (SpO2) monitoring can be of great value to patients with chronic diseases, enabling them and their clinicians to better manage their condition with reliable real-time and trend data. This study aimed to determine the SpO2 accuracy of a wearable ring pulse oximeter compared with arterial oxygen saturation (SaO2) in a controlled hypoxia study based on the International Organization for Standardization (ISO) 80601-2-61:2019 standard over the range of 70%-100% SaO2 in volunteers with a broad range of skin color (Fitzpatrick I to VI) during nonmotion conditions. In parallel, accuracy was compared with a calibrated clinical-grade reference pulse oximeter (Masimo Radical-7). Acceptable medical device accuracy was defined as a maximum of 4% root mean square error (RMSE) per the ISO 80601-2-61 standard and a maximum of 3.5% RMSE per the US Food and Drug Administration guidance. We performed a single-center, blinded hypoxia study of the test device in 11 healthy volunteers at the Hypoxia Research Laboratory, University of California at San Francisco, under the direction of Philip Bickler, MD, PhD, and John Feiner, MD. Each volunteer was connected to a breathing apparatus for the administration of a hypoxic gas mixture. To facilitate frequent blood gas sampling, a radial arterial cannula was placed on either wrist of each participant. One test device was placed on the index finger and another test device was placed on the fingertip. SaO2 analysis was performed using an ABL-90 multi-wavelength oximeter. For the 11 participants included in the analysis, there were 236, 258, and 313 SaO2-SpO2 data pairs for the test device placed on the finger, the test device placed on the fingertip, and the reference device, respectively. The RMSE of the test device for all participants was 2.1% for either finger or fingertip placement, while the Masimo Radical-7 reference pulse oximeter RMSE was 2.8%, exceeding the standard (4% or less) and the Food and Drug Administration guidance (3.5% or less). Accuracy of SaO2-SpO2 paired data from the 4 participants with dark skin in the study was separately analyzed for both test device placements and the reference device. The test and reference devices exceeded the minimum accuracy requirements for a medical device with RMSE at 1.8% (finger) and 1.6% (fingertip) and for the reference device at 2.9%. The wearable ring meets an acceptable standard of accuracy for clinical-grade SpO2 under nonmotion conditions without regard to skin color. ClinicalTrials.gov NCT05920278; https://clinicaltrials.gov/study/NCT05920278.

Comparison of invasive blood pressure monitoring vs. non-invasive blood pressure monitoring in critically ill children receiving vasoactive agents-a prospective observational study.

The primary aim of this study was to compare non-invasive blood pressure (NIBP) measurement using the automated oscillometric method with invasive blood pressure (IBP) measurement using peripheral arterial line insertion in critically ill children receiving vasoactive agents. Single-centre, prospective cohort study. Tertiary care 15 bedded Pediatric ICU in Urban Indian city. All critically ill children between the ages of 1 month to 16 years with shock on vasoactive medications and with IBP monitoring. Forty children with 1,072 paired BP measurements were incorporated in the final analysis. Among all normotensive children (Total number of paired measurements = 623) receiving vasoactive agents, Bland-Altman analysis revealed an acceptable agreement between Invasive mean blood pressure (MBP) and non-invasive MBP with a bias of -2.10 mmHg (SD 11.35). The 95% limits of agreement were from -24.34 to 20.14 mmHg. In children with hypotension (Total number of paired measurements = 449), Bland-Altman analysis showed disagreement between Invasive MBP and non-invasive MBP i.e., a bias of -8.44 mmHg (SD 9.62). The 95% limits of agreement were from -27.29 to 10.41 mmHg. A limited agreement exists between invasive blood pressure (IBP) and non-invasive blood pressure (NIBP) measurements in critically ill children requiring vasoactive agents. This discrepancy can lead to either an underestimation or an overestimation of blood pressure. While NIBP can serve as a screening tool for hemodynamically stable children, those who are hemodynamically unstable and necessitate the initiation of vasoactive agents should undergo IBP monitoring.

A Computational Investigation on Chitosan Derivatives using Pharmacophore- based Screening, Molecular Docking, and Molecular Dynamics Simulations against Kaposi Sarcoma.

Cancer is one of the most dangerous illnesses to the human body due to its severity and progressive nature. Kaposi's Sarcoma (KS) tumor can appear as painless purple spots on the legs, foot, or face. This cancer develops in the lining of lymph arteries and blood vessels. Along with the enlargement of lymph nodes, the vaginal region and the mouth portion are the additional target areas of KS. DNA-binding proteins known as Sox proteins are found in all mammals and belong to the HMG box superfamily. They controlled a wide range of developmental procedures, such as the formation of the germ layer, the growth of organs, and the selection of the cell type. Human developmental abnormalities and congenital illnesses are frequently caused by the deletion or mutation of the Sox protein. The purpose of this study is to determine the promising Kaposi's sarcoma inhibitors through computational studies. In this present study computational approaches were used to evaluate the anti- carcinogenic efficacy against Kaposi's sarcoma. Ligand-based pharmacophore screening was performed utilising four different chemical libraries (Asinex, Chembridge, Specs, and NCI Natural products (NSC)) depending on the top hypothesis. The top hits were examined using molecular docking, absorption, distribution, metabolism and excretion. Highest occupied molecular orbital and lowest unoccupied molecular orbital were analysed to determine the lead compounds' biological and pharmacological efficacy. The results of the study indicated that the leading candidates were possible SOX protein inhibitors. A pharmacophore model to inhibit the production of SOX protein in Kaposi Sarcoma was generated in this computational experiment using a set of 19 Chitosan compounds. The results revealed that the top hits responded to all of the pharmacological druglikening criteria and had the best interaction residues, fitness scores, and docking scores. The resulting leads might be potential Kaposi's Sarcoma alternative treatments.

Agreement between noninvasive oscillometric and invasive intra-arterial blood pressure in children with ruptured brain arteriovenous malformations

BackgroundDivergence between intra-arterial catheters blood pressure (ABP) and noninvasive oscillometry (NIBP) may affect the care of children with brain arteriovenous malformations (bAVMs). We described the agreement between ABP and NIBP in these children. MethodsWe conducted a retrospective review of patients admitted to the pediatric intensive care unit between 2017 and 2023 with bAVM rupture. Paired ABP and NIBP measurements were collected. Bland-Altman analyses were used to assess agreement. Correlation analysis was conducted between higher ABP and divergence between systolic BP (SBP) measurements. Hypertension was defined as mean arterial pressure (MAP) exceeding age-based 95th percentile. ResultsThirty-four patients with 1901 BP pairs were observed. Bias overall was acceptable, but standard deviation (SD) was high. The best agreement of MAP was in non-hypertensive (bias 1.23 mmHg, SD 8.03 mmHg) and radial arterial catheters (bias 1.83 mmHg, SD 9.08 mmHg) subgroups. Bias for SBP was higher in hypertension (10.98 mmHg) and in infratentorial bAVMs (7.42 mmHg), suggesting poorer agreement in these subgroups. There were significant correlations between intra-arterial MAP and SBP divergence (R = +0.346, p<.001) and between intra-arterial SBP and SBP divergence (R = +0.677, p<.001), suggesting divergence widens with higher BP. Around 25 % of measurement pairs diverged to where one measurement crossed the clinical threshold for treatment, while the other did not, with ABP being more frequently higher than NIBP. ConclusionsThere is good agreement between ABP and NIBP, particularly in non-hypertensive ranges and with radial arterial catheters. Measurements, however, diverge in hypertension. Further research must define age-based thresholds, validate methods of BP measurement, and determine the effect of BP reduction on outcomes in these children.

Implementing Ambulation Safety Checklists for Hemodynamically Stable Patients With Pulmonary Artery Catheters in the Step-down Unit.

Implementing Ambulation Safety Checklists for Hemodynamically Stable Patients With Pulmonary Artery Catheters in the Step-down Unit.

QAPI 121 - Closed Systems: Are Conventional Arterial Line Monitoring and Sampling Systems Contributing to Central Line Associated Bloodstream Infections (CLABSI(s)?

QAPI 121 - Closed Systems: Are Conventional Arterial Line Monitoring and Sampling Systems Contributing to Central Line Associated Bloodstream Infections (CLABSI(s)?

The left ventricle increases contractility in response to baroreceptor unloading, which is sympathetically-mediated in the anesthetized rat.

Contemporary discussion of the baroreflex includes the efferent vascular-sympathetic and cardio-vagal arms. Since sympathetic post-ganglionic neurons also innervate the left ventricle (LV), it is oft-assumed that the LV produces a sympathetically-mediated increase in contractility during baroreceptor unloading, but this has not been characterized using a load-independent index of contractility. We aimed to determine a) whether LV contractility increases in response to baroreceptor unloading, and b) whether such increases are mediated via the sympathetic or parasympathetic arm of the autonomic nervous system. Ten male Wistar rats were anesthetized (urethane) and instrumented with arterial and LV pressure-volume catheters to measure mean arterial pressure (MAP) and load-independent LV contractility [maximal rate of increase in pressure adjusted to end-diastolic volume (PAdP/dtmax)], respectively. Rats were placed in a servo-controlled lower-body negative pressure (LBNP) chamber to reduce MAP by 10% for 60s to mechanically unload baroreceptors under control conditions. LBNP was repeated in each animal following infusions of cardiac autonomic blockers using esmolol (sympathetic), atropine (parasympathetic), and esmolol+atropine. Under control conditions, PAdP/dtmax increased during baroreceptor unloading (26±6 vs. 31±9 mmHg·s-1·μL-1, p=0.031). During esmolol, there was no increase in LV contractility during baroreceptor unloading (11±2 vs. 12±2, p=0.125); however, during atropine, there was an increase in LV contractility during baroreceptor unloading (26±6 vs. 31±9, p=0.019). During combined esmolol and atropine, there was a small increase in contractility vs control (13±3 vs. 15±4, p=0.046). Our results demonstrate that, in anesthetized rats, LV contractility increases in response to baroreceptor unloading, which is largely sympathetically mediated.

3D transesophageal echocardiographic visualization of the pulmonary artery catheter through the tricuspid valve and their position relative to the tricuspid valve leaflets

BackgroundThe tricuspid valve is an atrioventricular valve consisting of three lobes. We used the 3D transesophageal echocardiography to visualize position of the pulmonary artery catheter at the tricuspid valve annulus and examined where the catheter passed through at the level of the tricuspid annulus.MethodsIn this prospective and observational study, we monitored the pressure wave on patients undergoing cardiac surgery with the catheter placement by monitoring the pressure waveform for 8 months. We measured the time required for the catheter to pass through the tricuspid and pulmonary valves, respectively. We acquired the 3D image of the tricuspid valve by transesophageal echocardiography and determined the position of the pulmonary artery catheter at the level of the tricuspid annulus. The data were analyzed by Kruskal-Wallis test followed by Mann-Whitney test with Holm multiple comparisons. P < 0.05 was considered significant.ResultsOf the 116 cases, the pulmonary artery catheter passed through the tricuspid valve between antero-posterior leaflets in 78 cases (67.2 %), between septal-posterior leaflets in 25 cases (21.6 %), and between antero-septal leaflets in 2 cases (1.7 %) and the center in 11 cases (9.5 %), respectively. The time required for the catheter to pass through the pulmonary valves was significantly different among the catheter positions at the level of the tricuspid annulus.ConclusionThe pulmonary artery catheter location at the level of the tricuspid annulus can be identified using 3D transesophageal echocardiography. The location of the catheter significantly affects the pulmonary artery catheter placement time.

Novel weaning assessment for veno-arteriovenous to veno-venous extracorporeal membrane oxygenation using pump-controlled retrograde trial off.

Pump-controlled retrograde trial off (PCRTO) is described as an effective weaning strategy for veno-arterial extracorporeal membrane oxygenation (ECMO) in the guidelines. Contrastingly, there is no established weaning strategy for veno-arteriovenous (V-AV) ECMO. We report a novel application of PCRTO in a patient undergoing V-AV ECMO. A 49-year-old man had pneumonia and a history of kidney transplantation. Two days after intubation, respiratory failure progressed and veno-venous (V-V) ECMO was introduced. On day 7 after ECMO, the configuration was changed to V-AV ECMO owing to septic cardiomyopathy due to suspected cholangitis. On day 15, with partial haemodynamic improvement and persistent respiratory failure, PCRTO was performed; the patient was safely returned to V-V ECMO. In patients undergoing V-AV ECMO, PCRTO could have the potential to accurately simulate decannulation of the arterial cannula. This novel weaning strategy could be considered in patients undergoing V-AV ECMO.

Chronic inhibition of angiotensin converting enzyme lowers blood pressure in spontaneously hypertensive rats by attenuation of sympathetic tone: The role of enhanced baroreflex sensitivity

Spontaneously hypertensive rats (SHR) are characterized by sympathetic hyperactivity and insufficient parasympathetic activity, and their high blood pressure (BP) can be lowered by long-term inhibition of the renin-angiotensin system. The aim of our study was to determine the influence of chronic inhibition of angiotensin converting enzyme (ACE) by captopril on cardiovascular regulation by the sympathetic and parasympathetic nervous system. Implanted radiotelemetric probes or arterial cannulas were used to measure mean arterial pressure (MAP), heart rate (HR), and arterial baroreflex in adult SHR and Wistar-Kyoto (WKY) rats under basal or stress conditions. MAP and the low-frequency component of systolic blood pressure variability (LF-SBPV, marker of sympathetic activity) were greater in SHR than in WKY rats. Under basal conditions chronic captopril treatment reduced both parameters more effectively in SHR, and the same was true during acute restraint stress. HR was similar in control rats of both strains, but WKY rats showed greater heart rate variability (HRV), indicating higher parasympathetic activity. Captopril administration increased HR in both strains, whereas HRV was decreased only in WKY. Chronic captopril treatment improved the impaired baroreflex-HR control in SHR by increasing the sensitivity but not the capacity of vagal arm of arterial baroreflex. Captopril treatment attenuated BP changes elicited by dimethylphenylpiperazinium (DMPP, agonist of nicotinic acetylcholine receptors), especially in SHR, indicating that sympathetic nerve transmission is facilitated by angiotensin II more in hypertensive than in normotensive animals. Thus, chronic ACE inhibition improves baroreflex sensitivity and lowers BP through both central and peripheral attenuation of sympathetic tone.

What is the weakest point of a secured aortic cannula in central extracorporeal membrane oxygenation?

The purpose of this study was to compare techniques for securing the aortic extracorporeal membrane oxygenation (ECMO) cannula, using in vitro models. Two models were studied: a tissue model using porcine aortas and a stand model replacing the aorta with a metal stand to study the system independent of the tissue. Interventions in each model were divided into three experimental groups: Group 1 (3-0 Prolene® + 20-French Medtronic Arterial Cannula EOPA™), Group 2 (4-0 Prolene® + 16-French Medtronic Arterial Cannula DLP Pediatric), and Group 3 (5-0 Prolene® + 8-French Medtronic Arterial Cannula DLP Pediatric). In separate experiments, both gradual and rapid forces were applied to the cannulas, starting with 9.8 Newtons and increasing exponentially if the cannula remained secured. Additionally, the method of securing the tourniquet and the number of ties securing the tourniquet to the cannula were evaluated. In the tissue model, even with a minimum force of 9.8 Newtons, the suture pulled through the aortic tissue, leaving sutures and ties intact. In the stand model, two purse-string sutures secured by two ligaclips held the cannula reliably and withstood higher total force. Dislodgement was prevented at forces close to 60 Newtons with only two hemostatic clips included in cannulation. The weakest part of the aortic ECMO cannulation system using in vitro experiments was the tissue. Assuming that these experiments translate in vivo, it is therefore critical to prevent any pull on the cannulas by securing ECMO cannulas and ECMO tubing to both the patient and the patient's bed. Sutures with a larger diameter withstand more force. Two medium hemostatic clips can secure Prolene® sutures within snares as safely as a mosquito hemostat. Two polypropylene purse-string sutures secured by two hemostatic clips were most reliable at greater forces. The rationale for publishing our experiments in this manuscript is to (1) communicate our quantification of possible contributing factors to this rare and likely catastrophic complication of unintended decannulation, (2) increase awareness about this potential complication, and (3) increase vigilance to assure prevention of this dreaded complication.

Correlation between the radial artery resistance index and the systemic vascular resistance index: a cross-sectional study.

Ultrasound measurement of the radial resistance index (RRI) in the anatomical snuffbox has been proposed as a useful method for assessing the systemic vascular resistance index (SVRI). This study aims to establish the correlation between SVRI measured by pulmonary artery catheter (PAC) and RRI. A cross-sectional study included all consecutive patients undergoing postoperative (POP) cardiac surgery with hemodynamic monitoring using PAC. Hemodynamic assessment was performed using PAC, and RRI was measured with ultrasound in the anatomical snuffbox. The Pearson correlation test was used to establish the correlation between RRI and SVRI measured using PAC. Hemodynamic behavior concerning RRI with a cutoff point of 1.1 (described to estimate under SVRI) was examined. Additionally, consistency between two evaluators was assessed for RRI using the intraclass correlation coefficient and Bland-Altman analysis. A total of 35 measurements were obtained. The average cardiac index (CI) was 2.73 ± 0.64L/min/m², and the average SVRI was 1967.47 ± 478.33 dyn·s·m²/cm5. The correlation between RRI and SVRI measured using PAC was 0.37 [95% CI 0.045-0.62]. The average RRI was 0.94 ± 0.11. RRI measurements > 1.1 had a mean SVRI of 2120.79 ± 673.48 dyn·s·m²/cm5, while RRI measurements ≤ 1.1 had a mean SVRI of 1953.1 ± 468.17 dyn·s·m²/cm5 (p = 0.62). The consistency between evaluators showed an intraclass correlation coefficient of 0.88 [95% CI 0.78-0.93], and Bland-Altman analysis illustrated adequate agreement of RRI evaluators. For patients in cardiac surgery POP, the correlation between the SVRI measured using PAC and the RRI measured in the anatomical snuffbox is low. Using the RRI as a SVRI estimator for patients is not recommended in this clinical scenario.

INJEX50 could improve the success rate of local anesthesia for arterial cannulation in the pediatric intensive care unit: Arandomized, double-blind, single-center study.

Quick arterial cannulation is required in pediatric emergency situation, which require effective local anesthesia to avoid withdrawal movement. However, pediatric local anesthesia could be difficult because of withdrawal movement. Jet injectors, which are needleless and provide local anesthesia quickly, could be helpful for pediatric local anesthesia during arterial cannulation. This study aimed to examine whether new jet injector "INJEX50" could improve the success rate of local anesthesia for arterial cannulation in pediatric intensive care unit compared with the current standard of care, infiltration using a 26-gauge needle. This study was a randomized, double-blind, single-center study. Participants were infants and young children in the pediatric intensive care unit, who required an arterial line. Local anesthesia was performed with either a 26-gauge needle (group C) or INJEX50 (group I) before arterial cannulation. The primary outcome (success of local anesthesia) was the presence of withdrawal movement at the time of skin puncture for arterial cannulation. The secondary outcomes included rescue sedation during arterial cannulation. Data were analyzed using Fisher's exact test and the Mann-Whitney U-test, with values of p < .05 considered statistically significant. Seventy patients were randomly assigned to groups C and I. The local anesthesia success rate in group I (30/35 [86%]) was significantly higher than that in group C (15/35 [43%], odds ratio, 8.00; 95% confidence interval, 2.51-25.5; p = .0005). In conclusion, INJEX50 could improve success rate of local anesthesia for arterial cannulation in pediatric intensive care unit compared with 26-gauge needle.

Ultrasound-guided Axillary Artery Catheter Placement and Associated Complications in Critically Ill Patients.

Arterial catheter placement for hemodynamic monitoring is commonly performed in critically ill patients. The radial and femoral arteries are the two sites most frequently used; there is limited data on the use of the axillary artery for this purpose. The aim of this study was to investigate the rate of complications from ultrasound-guided axillary artery catheter placement in critically ill patients. A retrospective study at a tertiary care center of patients admitted to an intensive care unit who had ultrasound-guided axillary artery catheter placement during admission. Primary outcome of interest was catheter related complications, including bleeding, vascular complications, compartment syndrome, stroke or air embolism, catheter malfunction, and need for surgical intervention. This study identified 88 patients who had an ultrasound-guided axillary artery catheter placed during their admission. Of these 88, nine patients required multiple catheters placed, for a total of 99 axillary artery catheter placement events. The median age was 64 [IQR 48, 71], 41 (47%) were female, and median body mass index (BMI) was 26 [IQR 22, 30]. The most common complication was minor bleeding (11%), followed by catheter malfunction (2%), and vascular complications (2%). Univariate analyses did not show any association between demographics and clinical variables, and complications related to axillary arterial catheter. The most common complication found with ultrasound-guided axillary artery catheter placement was minor bleeding, followed by catheter malfunction, and vascular complications. Ultrasound-guided axillary arterial catheters are an alternative in patients in whom radial or femoral arterial access is difficult or not possible to achieve.

The CHOIR study: acute hemodynamic effects of different pacing strategies in hypertrophic obstructive cardiomyopathy

Abstract Background The majority of patients with hypertrophic cardiomyopathy present with dynamic left ventricular (LV) outflow tract obstruction (LVOTO), referred to as hypertrophic obstructive cardiomyopathy (HOCM). Symptomatic treatment aims at reducing LVOTO with either medical therapy, invasive septal reducing therapies, or pacemaker therapy. There is conflicting evidence regarding the efficacy of pacemaker therapy. The effect of pacing strategies at physical exertion has not been investigated in HOCM. Purpose To identify the optimal pacing strategy for reducing LVOTO without compromising cardiac output at rest and exercise in HOCM. Methods In this ongoing project, we have so far included eight patients with symptomatic HOCM referred to our hospital for alcohol septal ablation (ASA). The day before ASA, we placed temporary pacing leads in the right atrium, the right ventricular (RV) apex and on the LV lateral wall. We also inserted a pulmonary artery catheter and performed per operative echocardiography. All patients had sinus rhythm. Intrinsic rhythm served as baseline and was followed by atrial sensed RV pacing, LV pacing and biventricular (BiV) pacing at rest and during supine cycling. We assessed LVOTO by echocardiography, and cardiac output by the thermodilution method under intrinsic rhythm and all pacing modalities. Results The mean age was 52±15 years, and two of eight patients were female. The mean maximal LV wall thickness was 16±1 mm. The resting LVOTO was 50±23 mmHg. Due to difficulties in placing the LV lead within a reasonable time frame, complete study protocol was not performed in all patients. All eight patients performed RV pace at rest, but only five patients (63 %) were LV and BiV paced at rest. Five patients performed supine cycling but only four patients completed with RV and BiV pacing. The graphs display LVOTO and CO in sinus rhythm and the different pacing maneuvers at rest and during supine cycling. At rest, 6 out of 8 patients (75%) had LVOTO reduction during RV pace, and CO was unchanged. Four of five patients (80%) had LVOTO reduction during BiV and LV pace compared to sinus rhythm, also with unchanged CO. During supine cycling four of five patients (80%) had a reduction of the LVOTO gradient during RV and BiV pacing, without significant CO change. No complications occurred during the interventions. Conclusion In this ongoing study on cardiac pacing in HOCM, RV, LV, and BiV pacing reduced LVOTO while CO remained unchanged at rest and during exercise.

Flow capabilities of arterial and drainage cannulae during venoarterial extracorporeal membrane oxygenation: A simulation model.

Large cannulae can increase cannula-related complications during venoarterial extracorporeal membrane oxygenation (VA ECMO). Conversely, the ability for small cannulae to provide adequate support is poorly understood. Therefore, we aimed to evaluate a range of cannula sizes and VA ECMO flow rates in a simulated patient under various disease states. Arterial cannulae sizes between 13 and 21 Fr and drainage cannula sizes between 21 and 25 Fr were tested in a VA ECMO circuit connected to a mock circulation loop simulating a patient with severe left ventricular failure. Systemic and pulmonary hypertension, physiologically normal, and hypotension were simulated by varying systemic and pulmonary vascular resistances (SVR and PVR, respectively). All cannula combinations were evaluated against all combinations of SVR, PVR, and VA ECMO flow rates. A 15 Fr arterial cannula combined with a 21 Fr drainage cannula could provide >4L/min of total flow and a mean arterial pressure of 81.1 mmHg. Changes in SVR produced marked changes to all measured parameters, while changes to PVR had minimal effect. Larger drainage cannulae only increased maximum circuit flow rates when combined with larger arterial cannulae. Smaller cannulae and lower flow rates could sufficiently support the simulated patient under various disease states. We found arterial cannula size and SVR to be key factors in determining the flow-delivering capabilities for any given VA ECMO circuit. Overall, our results challenge the notion that larger cannulae and high flows must be used to achieve adequate ECMO support.

The anesthesiologist's guide to swine trauma physiology research: a report of two decades of experience from the experimental traumatology laboratory.

Swine are one of the major animal species used in translational research, with unique advantages given the similar anatomic and physiologic characteristics as man, but the investigator needs to be familiar with important differences. This article targets clinical anesthesiologists who are proficient in human monitoring. We summarize our experience during the last two decades, with the aim to facilitate for clinical and non-clinical researchers to improve in porcine research. This was a retrospective review of 337 swine with a mean (SD) weight 60 (4.2) kg at the Experimental Traumatology laboratory at Södersjukhuset (Stockholm south general hospital) between 2003 and 2023, including laboratory parameters and six CT-angiography examinations. Swine may be ventilated through the snout using a size 2 neonatal mask. Intubate using a 35cm miller laryngoscope and an intubating introducer. Swine are prone to alveolar atelectasis and often require alveolar recruitment. Insert PA-catheters through a cut-down technique in the internal jugular vein, and catheters in arteries and veins using combined cut-down and Seldinger techniques. Cardiopulmonary resuscitation is possible and lateral chest compressions are most effective. Swine are prone to lethal ventricular arrhythmias, which may be reversed by defibrillation. Most vital parameters are similar to man, with the exception of a higher core temperature, higher buffer bases and increased coagulation. Anesthesia methods are similar to man, but swine require five times the dose of ketamine. Swine share anatomical and physiological features with man, which allows for seamless utilization of clinical monitoring equipment, medication, and physiological considerations.

#1328 Haemodynamic effects of low versus high dialysate bicarbonate concentration in haemodialysis patients

Abstract Background and Aims Haemodialysis (HD) treatment using standard dialysate bicarbonate concentrations cause transient metabolic alkalosis possibly associated with haemodynamic instability. We performed a detailed comparison of blood pressure (BP), haemodynamic parameters, electrolytes and orthostatic BP response with low (LDB) versus high dialysate bicarbonate concentration (HDB). Method Fifteen HD patients were examined in a single-blind, randomised, controlled, crossover study. Participants underwent a 4-hour HD session with dialysate bicarbonate concentration of 30 mmol/l (LDB) or 38 mmol/l (HDB) with one week between interventions. During HD, cardiac output (CO), total peripheral resistance (TPR), stroke volume (SV) and central blood volume were measured with ultrasound dilution technique (Transonic). Throughout dialysis, blood samples were obtained from the arterial cannula. Orthostatic BP was measured pre and post HD. Results With similar ultrafiltration volume (2.6 litres), systolic BP tended to decrease more during HDB compared to LDB (Fig. 1 and Table 1); the mean (95% confidence interval) between treatment differences in systolic BP were: 8 (-4;20) mmHg (end of HD) and 7 (0;15) mmHg (post HD). SV decreased (Fig. 2) whereas TPR increased significantly more during HDB compared to LDB with mean between treatment differences: SV: 12 (1;23) ml; TPR: -2.9 (-5.3;-0.5) mmHg/(L/min). CO tended to decrease more with HDB compared to LDB with mean between treatment difference 0.7 (0.0;1.4) L/min. HDB caused alkalosis, hypocalcaemia and lower plasma potassium, whereas patients remained normocalcaemic with normal pH during LDB (Table 1). Orthostatic BP response after dialysis did not differ significantly. Conclusion HDB compared to LDB was associated with hypocalcaemia and alkalosis and a more pronounced hypokalaemia which may impair preservation of BP, SV and CO during HD.