P149 The role of OSA pathophysiological traits on mandibular advancement treatment response and efficacy of a novel mandibular advancement device

Mandibular advancement devices (MAD) are an effective therapy for OSA. However, treatment response is difficult to predict. Recent studies have investigated the influence of OSA endotypes on MAD outcomes albeit using simplified endotyping methods. We aimed to prospectively quantify and compare OSA pathophysiological traits between responders and non-responders to a novel MAD using gold-standard endotyping methodology. Data from 30 OSA patients (AHI>10events/h) are analysed to date. OSA was confirmed via in-laboratory polysomnography. Next, a detailed physiology night was conducted before MAD therapy. Participants were instrumented with EEG, nasal mask, pneumotachograph, epiglottic pressure catheter and intramuscular genioglossus electrodes to quantify baseline OSA pathophysiological traits. Pcrit was quantified via CPAP drops and non-anatomical traits from naturally occurring respiratory events. Participants were fitted with a novel MAD with a built-in oral airway (Oventus O2Vent Optima™) and titrated to ≥75% of maximum mandibular advancement. A treatment efficacy PSG followed therapy acclimatisation. OSA severity decreased by 41±30% (25.1[16.3,39.2] vs. 12.1[7.3,20.0] events/h P<0.001) with MAD therapy. Similar reductions occurred in participants with high nasal resistance. OSA pathophysiological traits measured by gold-standard methodology were similar between responders and non-responders to MAD (residual AHI>10events/h). MAD responders had less collapsible airways at baseline when measured using simple estimates (Vpassive: 92.5[86.3,97.0] vs. 72.5[43.0,91.3] %Veupnea, P=0.022). The novel MAD reduced OSA severity by ~40% including in those with nasal obstruction. The upper airway was less collapsible in responders to MAD when estimated but not when directly measured. Simple estimates of OSA pathophysiological traits may be used to predict responses to MAD.

Descarte sanguíneo em sistema aberto de pressão arterial invasiva

Analisar o volume de solução a ser desprezado do cateter de pressão arterial invasiva a partir de quatro volumes mínimos para obtenção de amostra sanguínea com hemoconcentração eficaz para análise laboratorial. Estudo observacional transversal, com análise laboratorial, realizado em uma unidade de terapia intensiva no Estado do Rio de Janeiro. Os dados coletados foram armazenados no software Microsoft Excel® e analisados no SPSS Statistics®20.0, por análise estatística descritiva e de variância usando ANOVA e Tukey. Foram analisadas 157 amostra e percebeu-se que mesmo em comparações múltiplas não há diferença significativa entre os quatro volumes analisados, isto é, os volumes comparados não evidenciaram diferença dos resultados dos valores de hematócrito e hemoglobina. Concluiu-se que é possível recomendar o menor volume a ser desprezado do cateter de pressão arterial invasiva para uma amostra sanguínea eficaz, sendo este o volume de 1,5ml para cateteres arteriais radiais ou femorais.Descritores: Monitorização Hemodinâmica, Coleta de Amostras Sanguíneas, Cuidados Críticos. Blood disposal in an open invasive blood pressure systemAbstract: Analyze the volume of solution to be discarded from the invasive blood pressure catheter from four minimum volumes to obtain blood samples with effective hemoconcentration for laboratory analysis. Cross-sectional observational study, with laboratory analysis, carried out in an intensive care unit in the State of Rio de Janeiro. The collected data were stored in Microsoft Excel® software and analyzed using SPSS Statistics®20.0, using descriptive and variance statistical analysis using ANOVA and Tukey. 157 samples were analyzed and it was noticed that even in multiple comparisons there is no significant difference between the four volumes analyzed, that is, the volumes compared did not show any difference in the results of the hematocrit and hemoglobin values. It was concluded that it is possible to recommend the smallest volume to be discarded from the invasive blood pressure catheter for an effective blood sample, this being the volume of 1.5 ml for radial or femoral arterial catheters.Descriptors: Hemodynamic Monitoring, Blood Specimen Collection, Critical Care. Eliminación de sangre en un sistema abierto de presión arterial invasivaResumen: Analice el volumen de solución que se desechará del catéter invasivo de presión arterial a partir de cuatro volúmenes mínimos para obtener muestras de sangre con hemoconcentración efectiva para análisis de laboratorio. Estudio observacional transversal, con análisis de laboratorio, realizado en una unidad de cuidados intensivos en el estado de Río de Janeiro. Los datos recopilados se almacenaron en el software Microsoft Excel® y se analizaron usando SPSS Statistics®20.0, usando análisis estadísticos descriptivos y de varianza usando ANOVA y Tukey. Se analizaron 157 muestras y se observó que, incluso en comparaciones múltiples, no existe una diferencia significativa entre los cuatro volúmenes analizados, es decir, los volúmenes comparados no mostraron ninguna diferencia en los resultados de los valores de hematocrito y hemoglobina. Se concluyó que es posible recomendar que se descarte el volumen más pequeño del catéter invasivo de presión arterial para obtener una muestra de sangre efectiva, siendo este el volumen de 1,5 ml para catéteres arteriales radiales o femorales.Descriptores: Monitorización Hemodinâmica, Recolección de Muestras de Sangre, Cuidados Críticos.

CT-Guided Placement of a Neuromonitoring Suite in Swine for Trauma and Resuscitation Research

Background: This manuscript aims to describe a standardized method for placement of a neuromonitoring suite into the brain of a porcine model using CT guidance for use in trauma and resuscitation research. Methods: A baseline CT allowed for precise planning of the placement of the neuromonitoring suite including measurement of skull thickness at the location of the intended burr hole. After the burr hole was drilled, three neuromonitoring probes (pressure catheter, temperature probe, and laser doppler flow probe) were advanced into the brain parenchyma of the swine. A subsequent CT confirmed appropriate placement of the neuromonitoring suite. Results: Effective placement of the neuromonitoring suite was accomplished successfully and without complication in 6 Yorkshire swine. Mean duration of the procedure was 49.6 minutes ± 6.3. Representative data from one animal includes the following presented as mean ± standard deviation: intracranial pressure of 10 ± 0 mmHg, cerebral perfusion pressure of 61 ± 1 mmHg, intracranial temperature of 34.8 ± 0 °C, and brain perfusion of 704 ± 13 relative perfusion units. Conclusions: This CT-guided method facilitates placement of a neuromonitoring suite in a safe and reliable manner. The use of a neuromonitoring suite using CT may offer valuable insight into cerebral perfusion in the context of endovascular resuscitation.

Abstract 16830: Functional Stenosis After Undersizing Mitral Annuloplasty is Governed by Pre-Operative Mitral Valve Opening Geometry

Introduction: Surgical repair of functional mitral regurgitation (FMR) with undersizing mitral annuloplasty (UMA) is a common practice. Though excessive annular downsizing can improve coaptation, it raises the risk of functional mitral stenosis (FMS). Predicting if certain patients can develop FMS after UMA, can help with surgical planning and inform the safe levels of downsizing. In this study, we sought to investigate that the pre-operative diastolic geometry of the mitral valve can predict the risk of developing FMS with UMA. Methods: Pig mitral valves (n=8) were excised and mounted into a left heart simulator with steady diastolic flow only [ Fig1A ]. Three leaflet tethering patterns were mimicked in this model: annular dilation (AD), AD + asymmetric tethering (Asym) and AD + symmetric tethering (Sym) [ Fig1B ]. Under each condition, the annulus was downsized to different levels by an adjustable UMA [ Fig1C ]. Millar pressure catheter and Echocardiography were used to measure MV pressure gradient and diastolic configuration under various conditions. Results: Under each tethering geometry (AD, AD + Asym and AD + Sym respectively), pressure gradient gradually increases as the downsizing level increases. Also, at each specific level of downsizing, pressure gradient increases as the subannular tethering increases. Similarly, at each specific level of downsizing, EOA decreases as the subannular tethering increases. Under each tethering geometry, EOA also decreases as the downsizing level increases [ Fig1D ]. In addition, it is demonstrated that at different flow rates, both pressure gradient and EOA correlates with anterior diastolic angle, which is impacted mainly by preoperative subannular tethering [ Fig1E ]. Conclusions: In FMR, the hemodynamic outcome of MV after UMA depends on both the extent of annular downsizing and preoperative leaflet tethering geometry, both of which should be taken into account when deciding the optimal surgical intervention.

Abstract 15714: Intra-cardiac Pressure Estimation Using Subharmonic Aided Pressure Estimation (SHAPE) - A Clinical Evaluation

Introduction: Subharmonic aided pressure estimation (SHAPE) utilizes ambient pressure sensitivity of subharmonic signals from ultrasound contrast agents. The objective was to evaluate SHAPE with Definity (Lantheus Medical Imaging, Inc.) and Sonazoid (GE Healthcare) microbubbles for intra-cardiac pressure estimation. Hypothesis: Errors between SHAPE and pressures obtained during cardiac catheterization ≤ 5 mmHg. Methods: IRB approved this study. Consenting patients received an infusion of Definity (56 patients; 2 vials in 50 mL of saline; infusion rate: 4-10 mL/min) or Sonazoid (77 patients; rate (mL/hour) = 0.18 x weight in kg co-infused with saline at 120 mL/hour) during cardiac catheterization. Subharmonic data was acquired using a SonixTablet (PA 4/2 array; BK Ultrasound) synchronously with pressures from the left and right ventricles and the aorta (for left heart catheterizations only). Subharmonic data (in dB) was converted to pressure values (in mmHg) using calibration factors (mmHg/dB) based on data obtained from the aorta - utilizing pressures from the aorta either during the catheterization procedure or pressures obtained using a SphygmoCor (AtCor Medical Pty. Ltd.) device after the catheterization procedure. Clinically relevant pressures between the SHAPE technique and the pressure catheter were compared. Results: Correlation coefficient between the subharmonic and pressure data was -0.8 ± 0.1. With Definity, mean absolute errors ranged from 2.9 ± 1.5 to 5.0 ± 4.2 mmHg and from 4.4 ± 5.7 to 23.7 ± 28.3 mmHg for calibration factors utilizing aortic pressures from pressure catheter and SphygmoCor, respectively. For Sonazoid microbubbles, these errors ranged from 7.9 ± 12.0 to 10.1 ± 12.4 mmHg and from 7.2 ± 11.5 to 15.0 ± 23.2 mmHg, respectively. Two adverse events occurred during Definity infusion; these were resolved with return to baseline conditions. Conclusion: SHAPE may be useful for estimating intra-cardiac pressures noninvasively.

Intraamniotic Infection Rates after Intrauterine Pressure Catheter with and without Amnioinfusion

Objective This study aimed to examine the rates of intraamniotic infection between intrauterine pressure catheter with amnioinfusion and intrauterine pressure catheter alone. Study Design This was a retrospective cohort study of all women who had an intrauterine pressure catheter placement during labor at a tertiary referral hospital from January 2016 to June 2018. Outcomes were compared between women who had an intrauterine pressure catheter with amnioinfusion and intrauterine pressure catheter placement alone. The primary outcome was the rate of intraamniotic infection. Secondary outcomes included postpartum endometritis, postpartum hemorrhage (blood loss of ≥1,000 mL), quantitative blood loss (mL), and cesarean delivery. Multivariable logistic regression analysis was performed to calculate adjusted odds ratios (aOR) and 95% confidence interval (95% CI), controlling for age, race, body mass index, gestational age, and length of time of rupture of membranes. Results Of 1,268 women with an intrauterine pressure catheter, 298 (23.5%) also had an amnioinfusion. Women who had amnioinfusion through an intrauterine pressure catheter compared with those who had intrauterine pressure catheter alone had similar rates of intraamniotic infection (5.4 vs. 8.0%, crude p = 0.12, aOR 0.69; 95% CI 0.39–1.21), as well as secondary outcomes such as postpartum endometritis (3.0 vs. 2.5%, crude p = 0.61, aOR 1.12; 95% CI 0.49–2.53), postpartum hemorrhage (16.1 vs. 15.8%, crude p = 0.89, aOR 1.07; 95% CI 0.75–1.54), blood loss (479.5 vs. 500 mL, adjusted p = 0.89), and cesarean delivery (40.6 vs. 43.1%, crude p = 0.45, aOR 0.90; 95% CI 0.68–1.19). Conclusion Amnioinfusion was not associated with increased odds of intraamniotic infection compared with intrauterine pressure catheter placement alone. Key Points

Hemodynamic Characterization Of Pulmonary Artery Hypertension In A Rat

Introduction: Hemodynamic characterization of Pulmonary Artery (PA) hypertension helps to reveal progression of disease of pulmonary vasculature with constrictive remodeling of pulmonary arterioles, leading to right ventricle (RV) dysfunction and right sided HF failure. In this preclinical methodology article, surgical access, controlled mechanical ventilator set up and direct open chest measurements of PA hypertension is described, employing a rat model. Chronic PA injury was induced by single dose of monocrotaline (MCT). Methods & Aims: Setting of controlled mechanical volume ventilation (CMVV) was adjusted to limit its influence on RV preload and LV afterload in the instance of chronic pulmonary disease. Volume-ventilation setting of tidal volume and respiration rate was based on body weight. Isoflurane monoanesthesia was used without any premedication. PA pressures were compared using single and dual pressure catheter at 3-weeks post injury. Initially, single pressure catheter was positioned in the PA to assess data quality, while advanced data comparison (RV and PA pressures) during PA hypertension were made using dual pressure catheter. PA access was performed using “high” RV needle-stab, adjacent to the anatomical area of the PA outflow. Results: Introduction of single pressure catheter was successful and collected data during RV systole and diastole did not produce any major pressure artefacts. Final position in the main PA was guided by using visual cues i.e. distance of pressure sensor on the catheter, accompanied by simultaneous data recording from that location. In case of dual pressure catheter, RV and PA pressure data were successfully collected. During PA hypertension, systolic ranges were (41-52 mmHg) vs. naive (25-30 mmHg); diastolic (21-27 mmHg) vs. (9-14 mmHg); n=4. In PA hypertension, high afterload pressures complicated RV ejection, with PAP cresting about 1mmHg higher than the maximal RVP. During further assessment, RV ejection was complicated by higher PA dicrotic notch pressures, at the end of systole; for hypertension (37-41 mmHg) vs. naïve (16-21mmHg), n=4. Conclusions: This study revealed that good rat pressure data could be collected from the main trunk of PA using an open chest supported by CMVV. In future, hemodynamic influence of respiratory pump in close chest setting and its influence on chronic PA hypertension needs to be analyzed using solid state pressure catheter. To accomplish this, pressure catheter design should be based on rat’s RV and its outflow anatomy.