Arterial Line Pressure Research Articles

The Pressure Is on: Dorsal Versus Volar Univalves for Long-arm Casts.

Fiberglass casts are routinely used to treat fractures of the upper extremity. When posttraumatic edema is anticipated, the cast is often valved to hopefully prevent potential complications, especially compartment syndrome. Due to volar forearm compartments being most involved with upper extremity compartment syndrome, volar skin surface pressures (SSP) are paramount. Despite past literature showing that a univalved cast will retain a 3-point mold better than a bivalved cast, there is a paucity of information analyzing the effects of univalving on the volar SSP. We hypothesized that a volar univalve technique would have a greater decrease in the volar skin surface pressures compared to a dorsal univalve in long-arm casts. A 100-mL saline bag attached to an arterial line pressure transducer was placed between a long-arm cast and the skin along the volar forearm of a single adult volunteer. Fourteen casts were applied by a single certified orthopaedic technologist with 30 years of experience and assigned randomly to receive either a volar or dorsal univalve. We calculated the change in volar forearm SSP on each cast in 4 stages: isolated univalve, with a 3-mm cast spacer, with a 6-mm spacer, and with bivalve. Statistical analysis of the data was performed using a Mann-Whitney U test. When comparing volar versus dorsal univalve, volar SSP significantly dropped by a mean of 32.00 versus 20.43mmHg (P value=0.001) in stage I, 45.14 versus 38.00mmHg in stage II (P value=0.026), and 56.53 versus 49mmHg in stage III (P value=0.001). There was no significant difference between the 2 groups after a bivalve was performed at stage IV (P value=0.318). Our findings support that a volar univalve with a 6-mm spacer will provide the greatest reduction of skin surface pressure while theoretically maintaining the cast's structural integrity and biomechanical properties when compared to a bivalved cast. Level II, prospective comparative study.

NEUROPHYSIOLOGY INTRAOPERATIVE MONITORING (NIOM) PADA OPERASI DEFORMITIY CORRECTION AT ADOLESENT SCOLIOSIS

The use of neurophysiological intraoperative monitoring (NIOM) during spinal orthopaedic and neurosurgical procedures provides a challenge to the attending anaesthesiologist. Since all anaesthetic agents affect synaptic function, the choice of agent will be determined by the type of surgery and the NIOM modality employed. Had been performed surgery for scoliosis correction of spinal abnormalities in children aged 15 years with using of sensory and motoric NIOM. The surgery going under general anesthesia with the installation monitor invasive arterial line and central venous pressure during surgery for hemodynamic monitoring. Drugs used during anesthesia using balanced anesthesia technique with a combination of opioids, propofol and sevoflurane as inhalation. Muscle relaxants given intermittently for operator leisure and ventilation controls. Postoperative hospitalization in ICU with the aim of assessing the function of the respiratory and neurological of the patients and pain management.

280 Arterial Line versus Noninvasive Blood Pressure Monitoring in Hypertensive Emergencies

Blood pressure (BP) monitoring is important for managing patients with hypertensive emergencies. Management of such conditions often involves relatively narrow and specific blood pressure windows. While invasive arterial blood pressure (IABP) monitoring is considered the gold standard method of BP measurement, its usefulness is unclear. Although previous studies demonstrated differences between IABP and NIBP values, few had assessed whether these differences would affect clinical management. Our study aimed to determine whether the difference between NIBP and IABP would change BP management in patients with hypertensive emergencies. This was a prospective observational study of adult patients with any hypertensive emergency admitted to the Critical Care Resuscitation Unit (CCRU) at a quaternary academic center from January 2019—April 2021. We included consecutive patients with diagnoses of ischemic stroke, acute aortic disease, spontaneous intracranial hemorrhage (sICH), etc, and who required arterial monitoring. We excluded patients who had hypertensive diagnoses but required vasopressors due to overtreatment of anti-hypertensive medications or those who had arterial catheters prior to arrival. All arterial catheters were inserted upon patients’ arrival per CCRU clinical policy. Patients who had IABP and NIBP in the same extremity and four consecutive measurements of each modality following arterial catheter placement were eligible. Before arterial catheter placement, we recorded in real time clinicians’ decisions to manage patients’ systolic BP (SBP) according to the NIBP values and current guidelines, for example maintaining SBP ≤160 mmHg for patients with sICH. After the arterial catheter was placed, we again recorded in real time clinicians’ management of patients’ arterial SBP. We defined change in clinical management as any difference in blood pressure management (eg, adding a new antihypertensive agent, increasing or decreasing dose). We used Classification and Regression Tree (CART) analysis to identify sensitive and specific clinical predictors of management differences. A total of 183 patients were identified and analyzed, 71 (39%) female. Mean age was 63 years (standard deviation [SD] 14), mean body mass index (BMI) was 29 (6). Mean difference between IABP and NIBP and was 11 mmHg (95% CI 5-17). One hundred and seventeen patients (64%) had difference >10 mmHg between the two modalities, while 70 (38%) had a difference >20 mmHg. Seventy-nine patients (43%) had a change in management after arterial catheters were inserted. The most important factors in predicting management change included mean SBP >148 mmHg. Subsequent important factors were BMI >21, difference in BP value [IABP – NIBP] >6 mmHg, and diagnoses of ruptured abdominal aortic aneurysm, ischemic stroke + alteplase, any aortic dissection. Arterial BP monitoring identified a change in clinical management in almost half of patients with hypertensive emergencies. Clinicians should consider using arterial BP monitoring more frequently in the management of hypertensive emergencies, especially when strict BP goals are warranted.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Accuracy of Noninvasive Blood Pressure Versus Central Aortic Pressure in Patients Supported on Left Ventricular Assist Device Therapy.

Accuracy of Noninvasive Blood Pressure Versus Central Aortic Pressure in Patients Supported on Left Ventricular Assist Device Therapy.

Continuous Noninvasive Arterial Pressure Monitoring for Transcatheter Aortic Valve Replacement

The objective of the present study, which was conducted in patients undergoing transcatheter aortic valve replacement, was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA) with invasive radial artery pressure used as the reference method. The authors hypothesized that the ClearSight device is an accurate, precise, safe, and efficient method for arterial blood pressure measurement comparable with an invasive radial arterial line. The study included the retrospective review of 20 consecutive patients scheduled for elective transcatheter aortic valve replacement with the SAPIEN 3 transcatheter heart valve (Edwards Lifesciences) at a single tertiary academic hospital, who underwent monitoring with both the ClearSight device and an invasive radial arterial pressure line. The patients underwent transcatheter aortic valve replacement from October to December 2019. Single tertiary academic medical center. The study comprised 20 patients, with 2,243 unique blood pressure data points. None. A statistically significant correlation between the invasive radial arterial pressure line and the ClearSight device was observed for systolic blood pressure (correlation coefficient 0.86; p < 0.001), diastolic blood pressure (correlation coefficient 0.56; p < 0.001), and mean arterial pressure (correlation coefficient 0.78; p < 0.001). Bland-Altman analysis was used to assess the agreement of systolic blood pressure, diastolic blood pressure, and mean arterial pressure between the two methods. Results for systolic blood pressure between the arterial line and ClearSight device were as follows: bias = 9.8 ± 10.1, percentage bias = 7.6%, and mean error = 15.8%. Results for diastolic blood pressure between the arterial line and ClearSight device were as follows: bias = -5.9 ± 7.8, percentage bias = 10.7%, and mean error = 28.4%. Results for mean arterial pressure between the arterial line and ClearSight device were as follows: bias = 0.3 ± 7.4, percentage bias = 0.4%, and mean error = 18.3%. The concordance rates of systolic blood pressure, diastolic blood pressure, and mean arterial pressure were 100%, 95.1%, and 98.8%, respectively. The accuracy, agreement, and precision of the ClearSight device were convincing for mean arterial pressure, systolic blood pressure, and diastolic blood pressure for patients with severe aortic stenosis undergoing elective transcatheter aortic valve replacement.

Real-time bedside management and titration of partial resuscitative endovascular balloon occlusion of the aorta without an arterial line: Good for pressure, not for flow!

Partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) attempts to minimize ischemia/reperfusion injury while controlling hemorrhage. There are little data on optimal methods to evaluate and titrate partial flow, which typically requires invasive arterial line monitoring. We sought to examine the use of a miniaturized handheld digital pressure device (COMPASS; Mirador Biomedical, Seattle, WA) for pREBOA placement and titration of flow. Ten swine underwent standardized hemorrhagic shock. Carotid and iliac pressures were monitored with both arterial line and COMPASS devices, and flow was monitored by aortic and superior mesenteric artery flow probes. Partial resuscitative endovascular balloon occlusion of the aorta was inflated to control hemorrhage for 15 minutes before being deflated to try targeting aortic flow of 0.7 L/min (using only the COMPASS device) by an operator blinded to the arterial line pressures and aortic flow. Correlations between COMPASS and proximal/distal arterial line were evaluated, as well as actual aortic flow. There was strong correlation between the distal mean arterial pressure (MAP) and the distal COMPASS MAP (r = 0.979, p < 0.01), as well as between the proximal arterial line and the proximal COMPASS on the pREBOA (r = 0.989, p < 0.01). There was a significant but weaker correlation between the distal compass MAP reading and aortic flow (r = 0.47, p < 0.0001), although it was not clinically significant and predicted flow was not achieved in a majority of the procedures. Of 10 pigs, survival times ranged from 10 to 120 minutes, with a mean survival of 50 minutes, and 1 pig surviving to 120 minutes. Highly reliable pressure monitoring is achieved proximally and distally without arterial lines using the COMPASS device on the pREBOA. Despite accurate readings, distal MAPs were a poor indicator of aortic flow, and titration based upon distal MAPs did not provide reliable results. Further investigation will be required to find a suitable proxy for targeting specific aortic flow levels using pREBOA.

An iterative run-to-run learning model to derive continuous brachial pressure estimates from arterial and venous lines during dialysis treatment

Objective:Non-invasive continuous blood pressure monitoring is not yet part of routine practice in renal dialysis units but could be a valuable tool in the detection and prevention of significant variations in patient blood pressure during treatment. Feasibility studies have delivered an initial validation of a method which utilises pressure sensors in the extra-corporeal dialysis circuit, without any direct contact with the person receiving treatment. Our main objective is to further develop this novel methodology from its current early development status to a continuous-time brachial artery pressure estimator. Methods:During an in vivo patient feasibility study with concurrent measurement validation by Finapres Nova experimental physiological measurement device, real-time continuous dialysis line pressures, and intermittent occluding arm cuff pressure data were collected over the entire period of (typically 4-hour) dialysis treatments. There was found to be an underlying quasi-linear relationship between arterial line and brachial pressure measurements which supported the development of a mathematical function to describe the relationship between arterial dialysis line pressure and brachial artery BP. However, unmodelled non-linearities, dynamics and time-varying parameters present challenges to the development of an accurate BP estimation system. In this paper, we start to address the problem of physiological parameter time variance by novel application of an iterative learning run-to-run modelling methodology originally developed for process control engineering applications to a parameterised BP model. Results:The iterative run-to-run learning methodology was applied to the real-time data measured during an observational study in 9 patients, supporting subsequent development of an adaptive real-time BP estimator. Tracking of patient BP is analysed for all the subjects in our patient study, supported only by intermittent updates from BP cuff measurements. Conclusion:The methodology and associated technology is shown to be capable of tracking patient BP non-invasively via arterial line pressure measurement during complete 4-hour treatment sessions. A robust and tractable method is demonstrated, and future refinements to the approach are defined.

A Feasibility Study of Non-Invasive Continuous Estimation of Brachial Pressure Derived From Arterial and Venous Lines During Dialysis.

Objective: Intradialytic haemodynamic instability is a significant clinical problem, leading to end-organ ischaemia and contributing to morbidity and mortality in haemodialysis patients. Non-invasive continuous blood pressure monitoring is not currently part of routine practice but may aid detection and prevention of significant falls in blood pressure during dialysis. Brachial blood pressure is currently recorded intermittently during haemodialysis via a sphygmomanometer. Current methods of continuous non-invasive blood pressure monitoring tend to restrict movement, can be sensitive to external disturbances and patient movement, and can be uncomfortable for the wearer. Additionally, poor patient blood circulation can lead to unreliable measurements. In this feasibility study we performed an initial validation of a novel method and associated technology to continuously estimate blood pressure using pressure sensors in the extra-corporeal dialysis circuit, which does not require any direct contact with the person receiving dialysis treatment. Method: The paper describes the development of the measurement system and subsequent in vivo patient feasibility study with concurrent measurement validation by Finapres Nova physiological measurement device. Real-time physiological data is collected over the entire period of (typically 4-hour) dialysis treatment. Results: We identify a quasi-linear mathematical function to describe the relationship between arterial line pressure and brachial artery BP, which is confirmed in a patient study. The results from this observational study suggest that it is feasible to derive a continuous measurement of brachial pressure from continuous measurements of arterial and venous line pressures via an empirically based and updated mathematical model. Conclusion: The methodology presented requires no interfacing to proprietary dialysis machine systems, no sensors to be attached to the patient directly, and is robust to patient movement during treatment and also to the effects of the cyclical pressure waveforms induced by the hemodialysis peristaltic blood pump. This represents a key enabling factor to the development of a practical continuous blood pressure monitoring device for dialysis patients.

Accuracy of Doppler blood pressure measurement in HeartMate 3 ventricular assist device patients.

AimsOptimal blood pressure (BP) control is imperative to reduce complications, especially strokes, in continuous flow ventricular assist device (VAD) patients. Doppler BP has been shown to be an accurate and reliable non‐invasive BP measurement method in HeartMate II and HVAD patients. We examined whether Doppler BP is also accurate in patients with the HeartMate 3 VAD.Methods and resultsIn a prospective, longitudinal cohort of HeartMate 3 patients, arterial line BP and simultaneously measured Doppler opening pressure were obtained. Correlation and agreement between Doppler opening pressure and arterial line mean arterial pressure (MAP) versus systolic blood pressure (SBP) were analysed, as well as the effect of pulse pressure on the accuracy of Doppler opening pressure.A total of 589 pairs of simultaneous Doppler opening pressure and arterial line pressure readings were obtained in 43 patients. Doppler opening pressure had good correlation with intra‐arterial MAP (r = 0.754) and more closely approximated MAP than SBP (mean error 2.0 vs. −8.6 mmHg). Pulse pressure did not have a clinically significant impact on the accuracy of the Doppler BP method. These results in HeartMate 3 patients are very similar to previous results in HeartMate II and HVAD patients.ConclusionsDoppler BP method should be the default non‐invasive BP measurement method in continuous flow VAD patients including patients implanted with the HeartMate 3.

Hemodialysis efficiency management from the viewpoint of blood removal pressure.

Degradation of dialysis efficiency during hemodialysis, caused by incompatible indwelling needle size or increase in hematocrit, is a serious problem that can threaten a patient's life. This study aims to derive a quantitative index for determining the indwelling needle diameter that can maintain an appropriate blood flow rate, and presents an effective method to prevent a decrease in the actual blood flow rate. The relationships between the set flow rate and various parameters such as indwelling needle diameter, blood viscosity, and arterial line pressure are analyzed. A simple and reliable method for estimating the actual blood flow rate is derived from these relationships. A correlation between viscosity and actual blood flow rate is estimated adequately by regression analysis using a least-squares method. The relationship between Reynolds number and the flow rate reduction ratio is also evaluated. A new parameter (simple estimation method for actual blood flow) is derived by measuring the blood removal pressure. A pump control approach that uses blood removal pressure is suggested, which can be a future research direction in the field of hemodialysis.

Continual measurement of arterial dP/dtmax enables minimally invasive monitoring of left ventricular contractility in patients with acute heart failure

BackgroundContinuous, reliable evaluation of left ventricular (LV) contractile function in patients with advanced heart failure requiring intensive care remains challenging. Continual monitoring of dP/dtmax from the arterial line has recently become available in hemodynamic monitoring. However, the relationship between arterial dP/dtmax and LV dP/dtmax remains unclear. This study aimed to determine the relationship between arterial dP/dtmax and LV dP/dtmax assessed using echocardiography in patients with acute heart failure.MethodsForty-eight patients (mean age 70.4 years [65% male]) with acute heart failure requiring intensive care and hemodynamic monitoring were recruited. Hemodynamic variables, including arterial dP/dtmax, were continually monitored using arterial line pressure waveform analysis. LV dP/dtmax was assessed using continuous-wave Doppler analysis of mitral regurgitation flow.ResultsValues from continual arterial dP/dtmax monitoring were significantly correlated with LV dP/dtmax assessed using echocardiography (r = 0.70 [95% confidence interval (CI) 0.51–0.82]; P < 0.0001). Linear regression analysis revealed that LV dP/dtmax = 1.25 × (arterial dP/dtmax) (P < 0.0001). Arterial dP/dtmax was also significantly correlated with stroke volume (SV) (r = 0.63; P < 0.0001) and cardiac output (CO) (r = 0.42; P = 0.0289). In contrast, arterial dP/dtmax was not correlated with SV variation, dynamic arterial elastance, heart rate, systemic vascular resistance (SVR), or mean arterial pressure. Markedly stronger agreement between arterial and LV dP/dtmax was observed in subgroups with higher SVR (N = 28; r = 0.91; P < 0.0001), lower CO (N = 26; r = 0.81; P < 0.0001), and lower SV (N = 25; r = 0.60; P = 0.0014). A weak correlation was observed in the subjects with lower SVR (N = 20; r = 0.61; P = 0.0004); in the subgroups with higher CO (N = 22) and higher SV (N = 23), no significant correlation was found.ConclusionOur results suggest that in patients with acute heart failure requiring intensive care with an arterial line, continuous calculation of arterial dP/dtmax may be used for monitoring LV contractility, especially in those with higher SVR, lower CO, and lower SV, such as in patients experiencing cardiogenic shock. On the other hand, there was only a weak or no significant correlation in the subgroups with higher CO, higher SV, and lower SVR.

P3531Continual measurement of arterial dP/dtmax enables mini-invasive monitoring of left ventricular contractility in acute heart failure

Abstract Introduction Continuous reliable evaluating of left ventricular (LV) contractile function in patients with advanced heart failure requiring intensive care remains challenging. Recently, continual monitoring of dP/dtmax from arterial line became available for hemodynamic monitoring. However, the relation between arterial dP/dtmax and LV dP/dtmax measurement is not fully understood. Purpose The aim of our study was to determine the relation of arterial dP/dtmax and LV dP/dtmax assessed by echocardiography in patients with acute heart failure. Methods Forty-eight patients with acute heart failure requiring intensive care and hemodynamic monitoring were recruited into the study (mean age 70.4 years, 65% were males). Hemodynamic variables including arterial dP/dtmax were continually monitored using arterial line pressure waveform analysis. LV dP/dtmax was assessed using continuous-wave Doppler analysis of mitral regurgitation flow. Results The values from continual arterial dP/dtmax monitoring significantly correlated with the LV dP/dtmax assessed by echocardiography (r=0.72, 95% confidence interval [CI] 0.54–0.83, P&lt;0.0001). Linear regression revealed that (LV dP/dtmax) = 0.87×(arterial dP/dtmax) + 291, P&lt;0.0001. Arterial dP/dtmax significantly correlated also with the stroke volume (r=0.55, P&lt;0.0001), cardiac output (r=0.32, P=0.0289), mean arterial blood pressure (r=0.43, P=0.0155) and systolic blood pressure (r=0.79, P&lt;0001). On the other hand arterial dP/dtmax did not correlate with the systemic vascular resistance (SVR), heart rate, dynamic arterial elastance, diastolic blood pressure or central venous pressure. Conclusion Our results revealed that arterial dP/dtmax values tightly and highly significantly correlate with LV dP/dtmax. Arterial dP/dtmax could be, therefore, used for continual monitoring of LV contractility. Acknowledgement/Funding Institutional grant MH CZ - DRO (Na Homolce Hospital- NNH, 00023884), IG150501

Accuracy of Doppler blood pressure measurement in continuous-flow left ventricular assist device patients.

AimsAccurate blood pressure (BP) measurement in continuous‐flow ventricular assist device (CF‐VAD) patients is imperative to reduce stroke risk. This study assesses the accuracy of the Doppler opening pressure method compared with the gold standard arterial line method in CF‐VAD patients.Methods and resultsIn a longitudinal cohort of HeartMate II and HVAD patients, arterial line BP and simultaneously measured Doppler opening pressure were obtained. Overall correlation, agreement between Doppler opening pressure and arterial line mean vs. systolic pressure, and the effect of arterial pulsatility on the accuracy of Doppler opening pressure were analysed. A total of 1933 pairs of Doppler opening pressure and arterial line pressure readings within 1 min of each other were identified in 154 patients (20% women, mean age 55 ± 15, 50% HeartMate II and 50% HVAD). Doppler opening pressure had good correlation with invasive mean arterial pressure (r = 0.742, P < 0.0001) and more closely approximated mean than systolic BP (mean error 2.4 vs. −8.4 mmHg). Arterial pulsatility did not have a clinically significant effect on the accuracy of the Doppler opening pressure method.ConclusionsDoppler opening pressure should be the standard non‐invasive method of BP measurement in CF‐VAD patients.

Noninvasive Measures of Pulsatility and Blood Pressure During Continuous-Flow Left Ventricular Assist Device Support.

The reliability and validity of a palpable pulse and other noninvasive measures of pulsatility in patients on continuous-flow (CF) left ventricular assist device (LVAD) support have not been rigorously evaluated. We prospectively enrolled 23 patients who had CF-LVAD and an arterial catheter for blood pressure (BP) monitoring. Pulse pressure (PP) via the arterial line was compared with three noninvasive measures of pulsatility: presence of a palpable pulse, pulsatility index (PI), and aortic valve opening (AVO). In addition, the relationship between Doppler BP (DopBP) and arterial line pressures was evaluated. The study group comprised 30% females, 73% nonischemic cardiomyopathy, 87% axial flow device (HeartMate II [HMII]), and 13% centrifugal flow device (HeartWare ventricular assist device [HVAD]) support. Among four practitioners, the interobserver agreement for the presence of a palpable pulse was moderate (k = 0.41; 95% CI, 0.28-0.60). If the PP was ≥15 mm Hg, a radial pulse was palpated 82% of the time, whereas when the PP was <15 mm Hg, a radial pulse was palpated only 35% of the time. In subjects with a palpable pulse, there was a strong correlation between DopBP and systolic BP (SBP) (r = 0.94; 95% CI, 0.82-0.99), whereas the correlation between DopBP and mean arterial pressure (MAP) was much weaker (r = 0.42; 95% CI, 0.19-0.96). In subjects without a palpable pulse, there was a strong correlation between both the DopBP and SBP (r = 0.94; 95% CI, 0.80-1.0) and DopBP and MAP (r = 0.87; 95% CI, 0.77-1.00). Finally, PP was significantly associated with PI (odds ratio [OR], 0.3; 95% CI, 0.14-0.45; p = 0.0002) but not AVO (OR, 1.41: 95% CI, 0.70-2.83; p = 0.33). The presence of a palpable pulse has good interobserver agreement and allows for dichotomization of the DopBP to reflect the SBP in its presence and the MAP in its absence. This simple measure should be incorporated into BP management algorithms for CF-LVADs. The PI shows a modest correlation to PP.

In vitro evaluation of Capiox FX05 and RX05 oxygenators in neonatal cardiopulmonary bypass circuits with varying venous reservoir and vacuum-assisted venous drainage levels.

The purpose of this study was to evaluate the hemodynamic properties and microemboli capture associated with different vacuum-assisted venous drainage (VAVD) vacuum levels and venous reservoir levels in a neonatal cardiopulmonary bypass circuit. Trials were conducted in 2 parallel circuits to compare the performance of Capiox Baby RX05 oxygenator with separate AF02 arterial filter to Capiox FX05 oxygenator with integrated arterial filter. Arterial cannula flow rate to the patient was held at 500mL/min and temperature maintained at 32°C, while VAVD vacuum levels (0mm Hg, -15mm Hg, -30mm Hg, -45mm Hg, -60mm Hg) and venous reservoir levels (50mL, 200mL) were evaluated in both oxygenators. Hemodynamic parameters measuring flow, pressure, and total hemodynamic energy were made in real time using a custom-made data acquisition system and Labview software. Nearly 10cc bolus of air was injected into the venous line and gaseous microemboli detected using an Emboli Detection and Classification Quantifier. Diverted blood flow via the arterial filter's purge line and mean pressures increased with increasing VAVD levels (P<0.01). Mean pressures were lower with lower venous reservoir levels and were greater in RX05 groups compared to FX05 (P<0.01). Microemboli detected at the preoxygenator site increased with higher VAVD vacuum levels and lower venous reservoir levels (P<0.01). The amount of microemboli captured by the FX05 oxygenator with integrated arterial filter was greater than by the RX05 oxygenator alone, although both oxygenators were able to clear microemboli before reaching the pseudo-patient.

RF70 RESULTS FROM AN IN VIVO COMPARISON OF THE OPTIFLOW AND EZ GLIDE AORTIC DISPERSION CANNULAE

Background: Morbidity associated with embolization during cannulation in coronary artery bypass grafts (CABG) is strongly related to patient characteristics/comorbidities, the arterial cannulation site and the shape of the arterial cannula tip.. The desired features of an arterial cannula should be to prevent those morbid effects and focus on achieving higher flows with lower cannula pressures. Methods: To evaluate the in vivo performance of two aortic dispersion flow cannulas: Optiflow (Sorin Group, Italy) and EZ Glide (Edwards Lifesciences, USA) in relation to cannula pressures, pump flow rates and plasma free hemoglobin. Over a 12 month period we collected data on a prospective, randomized (1:1), non-blinded, monocentric study with a cohort of 30 patients (Optiflow group N = 15; EZ Glide group N = 15). Results: The Optiflow cannula was found to have decreasing cannula pressures as pump flow rates increased (112.3 ± 10.9 mmHg vs 131.1 ± 11.4 mmHg, p &lt; 0.0001). Results also indicated no significant differences between groups in plasma free hemoglobin increases (p = 0.41) or total microembolic signals counts during cardiac surgery (p = 0.63). Conclusions: Both Optiflow and EZ Glide dispersion flow arterial cannulas performed well, but the Optiflow cannula demonstrated an ability to increase pump flow rates with lower arterial line and cannula pressures than the EZ Glide cannula. This implies an ability to improve peripheral perfusion while reducing cannula shear stress and reducing the risk of endothelial damage in an area where the cannula jet hits the intraluminal aortic wall, thereby having the potential to reduce the risk of atherosclerotic plaque dislodgement.

Non-invasive monitoring using photoplethysmography technology.

We evaluated the accuracy and precision of a novel non-invasive monitoring device in comparison with conventional monitoring methods used in intensive care units (ICU). The study device was developed to measure blood pressure, pulse rate, respiratory rate, and oxygen saturation, continuously with a single sensor using the photoplethysmographic technique. Patients who were monitored with arterial pressure lines in the ICU were enrolled. Systolic and diastolic blood pressure, pulse rate, respiratory rate, and arterial oxygen saturation were measured continuously for 30min at 5-min intervals using the conventional methods and the study device. The primary outcome variable was blood pressure. Blood pressure measured by the study device highly correlated with the arterial pressure line values (correlation coefficients > 0.95). Percent errors for systolic, diastolic and mean blood pressures were 2.4% and 6.7% and 6.5%, respectively. Percent errors for pulse rate, respiratory rate and oxygen saturation were 3.4%, 5.6% and 1.4%, respectively. The non-invasive, continuous, multi-parameter monitoring device presented high level of agreement with the invasive arterial blood pressure monitoring, along with sufficient accuracy and precision in the measurements of pulse rate, respiratory rate, and oxygen saturation.

Flow Rate Through Pigtail Catheter Used for Left Heart Decompression in an Artificial Model of Extracorporeal Membrane Oxygenation Circuit.

In refractory cardiogenic shock, veno-arterial extracorporeal membrane oxygenation (ECMO) can be initiated. Although left heart decompression can be accomplished by insertion of a left atrial (LA) or left ventricular (LV) cannula using a percutaneous pigtail catheter, the venting flow rate according to catheter size and ECMO flow rate is unknown. We developed an artificial ECMO circuit. One liter saline bag with its pressure set to 20 mm Hg was connected to ECMO to mimic LV failure. A pigtail catheter was inserted into the 1 L saline bag to simulate LV unloading. For each pigtail catheter size (5-8 Fr) and ECMO flow rate (2.0-4.0 L/min), the moving distance of an air bubble that was injected through a three-way stopcock was measured in the arterial pressure line between the pigtail catheter and ECMO inflow limb. The flow rate was then calculated. We obtained the following equation to estimate the pigtail catheter flow rate.Pigtail vent catheter flow rate (ml/min) = 8×ECMOflow rate(L /min)+9×pigtail catheter size(Fr)- 57This equation would aid in designing of a further study to determine optimal venting flow rate. To achieve optimal venting flow, our equation would enable selection of an adequate catheter size.

Under Pressure: The Utility of Spacers in Univalved Fiberglass Casts.

Univalving fiberglass casts after fracture manipulation or extremity surgery reduces the risk of developing compartment syndrome (CS). Previous experiments have demonstrated that univalving decreases intracompartmental pressures (ICPs), but increases the risk for loss of fracture reduction due to altering the mechanical properties of the cast. The purpose of this study was to correlate cast valve width within a univalved cast model to decreasing ICP. Saline bags (1 L) were covered with stockinette, Webril, and fiberglass tape then connected to an arterial pressure line monitor. Resting pressure was recorded. A water column was added to simulate 2 groups (n=5 each) of clinical CS: low pressure CS (LPCS range, 28 to 31 mm Hg) and high pressure CS (HPCS, range, 64 to 68 mm Hg). After the designated pressure was reached, the fiberglass was cut (stockinette and Webril remained intact). Cast spacers were inserted into each univalve and secured with varying widths: position #1 (3 mm wide), #2 (6 mm), #3 (9 mm), and #4 (12 mm). Pressure was recorded after cutting the fiberglass and following each spacer placement. In LPCS and HPCS groups, after univalve and placement of spacer position #1, pressure dropped by a mean of 52% and 58%, respectively. Spacer #2, decreased the pressure by a mean of 78% and 80%, respectively. Both spacer sizes significantly decreased the underlying pressure in both groups. Spacer #3 and #4 progressively reduced pressure within the cast, but not statistically significantly more than the previous spacer widths. This experimental model replicates the iatrogenic elevation in interstitial compartment pressure due to rigid cast application, not necessarily a self-sustained true CS. Increasing the univalved cast spread by ≥9 mm of the initial cast diameter will reduce pressure to a pre-CS level; however, a spread of only 6 mm can effectively reduce the pressure to <30 mm Hg depending on the initial elevated ICP. Cutting the Webril and stockinette in our model yielded a pressure decrease of 91% and 94% from the starting experimental pressure in the LPCS and the HPCS groups, respectively. Although the utility of splitting fiberglass casts has been previously demonstrated, we present evidence highlighting the benefit of spacing the split by at least 6 to 9 mm.

PD49-04 INCREASED AUS RESERVOIR VOLUMES DO NOT CORRELATE WITH INCREASED PRESSURE DELIVERY

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Male Incontinence: Therapy II1 Apr 2016PD49-04 INCREASED AUS RESERVOIR VOLUMES DO NOT CORRELATE WITH INCREASED PRESSURE DELIVERY Katie Cunningham and O. Lenaine Westney Katie CunninghamKatie Cunningham More articles by this author and O. Lenaine WestneyO. Lenaine Westney More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2740AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The artificial urinary sphincter is the gold standard for the treatment of postprostatectomy incontinence. The 3-component AMS 800TM system includes a pressure regulating balloon (PRB), silicone urethral cuff and a control pump with associated tubing. The PRB is filled intra-operatively with 0.9% normal saline or an isotonic contrast mixture, delivers the occlusive force to the urethral cuff. Though the PRB has been available in a variety of 10 cm H2O pressure ranges from 41-100 cm H2O, the 61-70 cm H2O balloon is the most commonly utilized. The properties of the PRB – wall thickness, elasticity of the material (silicone elastomer) and the volume – are responsible for the resultant delivery pressure. According to the manufacturer’s device description, the pressure within the PRB is maintained within a certain range when a specific fluid volume is injected into the balloon. Anecdotally, urologists have increased the volume in the PRB in certain situations to accommodate the fluid requirements of a larger cuff or based on a hypothesis of augmenting the occlusive force. However, the effects of increasing volume in the PRB have not been objectively evaluated. The purpose of our study was to evaluate the pressure delivered by the AMS 800TM 61-70 cm H2O PRB at different volumes. METHODS We performed ex-vivo testing of two 61-70cmH20 pressure regulating balloons. The pressure transmitted by the PRB was measured at pre-designated volumetric intervals using a GE Dash 4000TM Vital Signs Monitor and an arterial line pressure transducer. After prepping the component, the PRB’s were sequentially filled with 20, 23, 25, 30 and 40 ccs of normal saline. Subsequently, we continued to test a single PRB from 50 cc to 100 cc of volume, recording the pressure at 10 cc increments. RESULTS Both 61-70 cm H2O PRB’s maintained stable pressures from 20-25 ccs. Recorded pressure transmission at 30-40 cc, while still in range, was reduced. Further PRB expansion resulted in the transduced pressure progressively dropping then going below the manufacturer’s specified range at volumes > 60cc (Figure 1). CONCLUSIONS The pressure delivery characteristics of the AMS 800 TM PRB allow for maintenance of the prescribed range up to a volume of 25cc. Filling of the PRB in a compliant space above that volume results in a drop of transmitted pressure rather than an increase. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1181-e1182 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Katie Cunningham More articles by this author O. Lenaine Westney More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...