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65-696: CVP may mean: Medicine [ edit ] Central venous pressure , the pressure of blood in the thoracic vena cava CVP (chemotherapy) , regime of Cyclophosphamide + Vincristine + Prednisone/Prednisolone Water [ edit ] Crane Valley Partnership, related to the River Crane, London , England Central Valley Project , water project in California, USA Transport [ edit ] Continuous Voyage Permit, related to Transport in Australia CVP,

130-406: A Doppler shift in the frequency of the returning ultrasound waves. This shift can then be used to calculate flow velocity and volume, and effectively cardiac output, using the following equations: where: Being non-invasive, accurate and inexpensive, Doppler ultrasound is a routine part of clinical ultrasound; it has high levels of reliability and reproducibility, and has been in clinical use since

195-465: A beaker and timer, and less variable than the Fick principle and thermodilution. Velocity-encoded MRI is based on the detection of changes in the phase of proton precession . These changes are proportional to the velocity of the protons' movement through a magnetic field with a known gradient. When using velocity-encoded MRI, the result is two sets of images, one for each time point in the cardiac cycle. One

260-622: A central arterial line, i.e., the femoral or axillary arterial line, is used as the calibrating technique. The Q value derived from cold-saline thermodilution is used to calibrate the arterial PP contour, which can then provide continuous Q monitoring. The PiCCO algorithm is dependent on blood pressure waveform morphology (mathematical analysis of the PP waveform), and it calculates continuous Q as described by Wesseling and colleagues. Transpulmonary thermodilution spans right heart, pulmonary circulation and left heart, allowing further mathematical analysis of

325-422: A dye, indocyanine green , into the right atrium of the heart. The dye flows with the blood into the aorta. A probe is inserted into the aorta to measure the concentration of the dye leaving the heart at equal time intervals [0, T ] until the dye has cleared. Let c ( t) be the concentration of the dye at time t . By dividing the time intervals from [0, T ] into subintervals Δ t , the amount of dye that flows past

390-595: A dynamic autonomic system such as those with sepsis. Pressure Recording Analytical Method (PRAM), estimates Q from the analysis of the pressure wave profile obtained from an arterial catheter—radial or femoral access. This PP waveform can then be used to determine Q . As the waveform is sampled at 1000 Hz, the detected pressure curve can be measured to calculate the actual beat-to-beat stroke volume. Unlike FloTrac, neither constant values of impedance from external calibration, nor form pre-estimated in vivo or in vitro data, are needed. PRAM has been validated against

455-610: A method trademarked by Cardiotronic, Inc., and shows promising results in a wide range of patients. It is currently approved in the US for use in adults, children and babies. Electrical cardiometry monitors have shown promise in postoperative cardiac surgical patients, in both haemodynamically stable and unstable cases. Velocity-encoded phase contrast Magnetic resonance imaging (MRI) is the most accurate technique for measuring flow in large vessels in mammals. MRI flow measurements have been shown to be highly accurate compared to measurements made with

520-448: A single cycle or averaged over several cycles. Invasive methods are well accepted, but there is increasing evidence that these methods are neither accurate nor effective in guiding therapy. Consequently, the focus on development of non-invasive methods is growing. This method uses ultrasound and the Doppler effect to measure cardiac output. The blood velocity through the heart causes

585-559: A special infusion set which is connected to a small diameter water column. If the water column is calibrated properly the height of the column indicates the CVP. In most intensive care units , facilities are available to measure CVP continuously. Normal values vary between 4 and 12 cm H 2 O. Factors that increase CVP include: Factors that decrease CVP include: Cardiac output In cardiac physiology , cardiac output ( CO ), also known as heart output and often denoted by

650-471: A subsidiary of Petróleos de Venezuela S.A. CVP analysis (Cost-Volume-Profit analysis) Customer value proposition Centerview Partners , an American independent investment banking firm Science and technology [ edit ] Content Vectoring Protocol Closest vector problem Circuit value problem , in computer science Other [ edit ] The Chess Variant Pages , A website about chess variants Topics referred to by

715-470: A supporting monitor (Vigileo or EV1000 monitor), derives left-sided cardiac output ( Q ) from a sample of arterial pulsations. The device uses an algorithm based on the Frank–Starling law of the heart , which states pulse pressure (PP) is proportional to stroke volume (SV). The algorithm calculates the product of the standard deviation of the arterial pressure (AP) wave over a sampled period of 20 seconds and

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780-417: A vascular tone factor (Khi, or χ) to generate stroke volume. The equation in simplified form is: S V = s t d ( A P ) ⋅ χ {\textstyle SV=\mathrm {std} (AP)\cdot \chi } , or, B P ⋅ k   ( c o n s t a n t ) {\textstyle BP\cdot k\mathrm {\ (constant)} } . Khi

845-399: Is a non-invasive method similar to Impedance cardiography; both methods measure thoracic electrical bioimpedance (TEB). The underlying model differs between the two methods; Electrical cardiometry attributes the steep increase of TEB beat-to-beat to the change in orientation of red blood cells. Four standard ECG electrodes are required for measurement of cardiac output. Electrical Cardiometry is

910-422: Is a useful tool to guide hemodynamic therapy . The cardiopulmonary baroreflex responds to an increase in CVP by decreasing systemic vascular resistance while increasing heart rate and ventricular contractility in dogs. Pulmonary capillary wedge pressure Normal CVP in patients can be measured from two points of reference: CVP can be measured by connecting the patient's central venous catheter to

975-422: Is also possible to quantify the stroke volume in real-time on a beat-for-beat basis. While MRI is an important research tool for accurately measuring Q , it is currently not clinically used for haemodynamic monitoring in emergency or intensive care settings. As of 2015 , cardiac output measurement by MRI is routinely used in clinical cardiac MRI examinations. The dye dilution method is done by rapidly injecting

1040-410: Is an anatomical image and the other is an image in which the signal intensity in each pixel is directly proportional to the through-plane velocity. The average velocity in a vessel, i.e., the aorta or the pulmonary artery , is quantified by measuring the average signal intensity of the pixels in the cross-section of the vessel then multiplying by a known constant. The flow is calculated by multiplying

1105-406: Is based on pulse power derivation and is not dependent on waveform morphology. FloTrac/Vigileo ( Edwards Lifesciences ) is an uncalibrated, haemodynamic monitor based on pulse contour analysis. It estimates cardiac output ( Q ) using a standard arterial catheter with a manometer located in the femoral or radial artery. The device consists of a high-fidelity pressure transducer, which, when used with

1170-402: Is designed to reflect arterial resistance; compliance is a multivariate polynomial equation that continuously quantifies arterial compliance and vascular resistance. Khi does this by analyzing the morphological changes of arterial pressure waveforms on a bit-by-bit basis, based on the principle that changes in compliance or resistance affect the shape of the arterial pressure waveform. By analyzing

1235-681: Is different from Wikidata All article disambiguation pages All disambiguation pages Central venous pressure CVP has been, and often still is, used as a surrogate for preload , and changes in CVP in response to infusions of intravenous fluid have been used to predict volume-responsiveness (i.e. whether more fluid will improve cardiac output ). However, there is increasing evidence that CVP, whether as an absolute value or in terms of changes in response to fluid, does not correlate with ventricular volume (i.e. preload ) or volume-responsiveness, and so should not be used to guide intravenous fluid therapy. Nevertheless, CVP monitoring

1300-460: Is limited by the absence of a widely accepted "gold standard" measurement. Cardiac output can also be affected significantly by the phase of respiration – intra-thoracic pressure changes influence diastolic filling and therefore cardiac output. This is especially important during mechanical ventilation, in which cardiac output can vary by up to 50% across a single respiratory cycle. Cardiac output should therefore be measured at evenly spaced points over

1365-554: Is not complete agreement on this point. The clinical use of this approach in the diagnosis, prognosis and therapy of a variety of diseases continues. Non-invasive ICG equipment includes the Bio-Z Dx, the Niccomo, and TEBCO products by BoMed. Ultrasound dilution (UD) uses body-temperature normal saline (NS) as an indicator introduced into an extracorporeal loop to create an atrioventricular (AV) circulation with an ultrasound sensor, which

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1430-416: Is not necessarily more reproducible is the measurement of the pulmonary valve to calculate right-sided CO. Although it is in wide general use, the technique is time-consuming and is limited by the reproducibility of its component elements. In the manner used in clinical practice, precision of SV and CO is of the order of ±20%. Ultrasonic Cardiac Output Monitor (USCOM) uses continuous wave Doppler to measure

1495-616: Is recorded and displayed on the COstatus HCM101 Monitor. Cardiac output is calculated from the area of the concentration curve using the Stewart-Hamilton equation. UD is a non-invasive procedure, requiring only a connection to the AV loop and two lines from a patient. UD has been specialised for application in pediatric ICU patients and has been demonstrated to be relatively safe although invasive and reproducible. Electrical cardiometry

1560-407: Is the product of the heart rate (HR), i.e. the number of heartbeats per minute (bpm), and the stroke volume (SV), which is the volume of blood pumped from the left ventricle per beat; thus giving the formula: Values for cardiac output are usually denoted as L/min. For a healthy individual weighing 70 kg, the cardiac output at rest averages about 5 L/min; assuming a heart rate of 70 beats/min,

1625-518: Is the rate of flow that is being calculated. The total amount of dye is: ∑ i = 1 n c ( t i ) ( F Δ t ) = F ∑ i = 1 n c ( t i ) ( Δ t ) {\displaystyle \sum _{i=1}^{n}c(t_{i})(F\Delta t)=F\sum _{i=1}^{n}c(t_{i})(\Delta t)} and, letting n → ∞ {\displaystyle n\rightarrow \infty } ,

1690-571: Is used to measure the dilution then to calculate cardiac output using a proprietary algorithm. A number of other haemodynamic variables, such as total end-diastole volume (TEDV), central blood volume (CBV) and active circulation volume (ACVI) can be calculated using this method. The UD method was firstly introduced in 1995. It was extensively used to measure flow and volumes with extracorporeal circuit conditions, such as ECMO and Haemodialysis , leading more than 150 peer reviewed publications. UD has now been adapted to intensive care units (ICU) as

1755-510: The descending thoracic aorta . An ultrasound probe is inserted either orally or nasally into the oesophagus to mid-thoracic level, at which point the oesophagus lies alongside the descending thoracic aorta . Because the transducer is close to the blood flow, the signal is clear. The probe may require re-focussing to ensure an optimal signal. This method has good validation, is widely used for fluid management during surgery with evidence for improved patient outcome, and has been recommended by

1820-611: The radial or femoral artery —and continuously measuring the PP waveform. This is generally done by connecting the catheter to a signal processing device with a display. The PP waveform can then be analysed to provide measurements of cardiovascular performance. Changes in vascular function, the position of the catheter tip or damping of the pressure waveform signal will affect the accuracy of the readings. Invasive PP measurements can be calibrated or uncalibrated. PiCCO ( PULSION Medical Systems AG, Munich, Germany) and PulseCO (LiDCO Ltd, London, England) generate continuous Q by analysing

1885-429: The volume clamp method of measuring continuous blood pressure. The principle of the volume clamp method is to dynamically provide equal pressures, on either side of an artery wall. By clamping the artery to a certain volume, inside pressure—intra-arterial pressure—balances outside pressure—finger cuff pressure. Peñáz decided the finger was the optimal site to apply this volume clamp method. The use of finger cuffs excludes

1950-522: The 1960s. Echocardiography is a non-invasive method of quantifying cardiac output using ultrasound. Two-dimensional (2D) ultrasound and Doppler measurements are used together to calculate cardiac output. 2D measurement of the diameter (d) of the aortic annulus allows calculation of the flow cross-sectional area (CSA), which is then multiplied by the VTI of the Doppler flow profile across the aortic valve to determine

2015-498: The COstatus device. The UD method is based on ultrasound indicator dilution. Blood ultrasound velocity (1560–1585 m/s) is a function of total blood protein concentration—sums of proteins in plasma and in red blood red cells—and temperature. Injection of body-temperature normal saline (ultrasound velocity of saline is 1533 m/s) into a unique AV loop decreases blood ultrasound velocity, and produces dilution curves. UD requires

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2080-479: The Doppler flow profile VTI. It uses anthropometry to calculate aortic and pulmonary valve diameters and CSAs, allowing right-sided and left-sided Q measurements. In comparison to the echocardiographic method, USCOM significantly improves reproducibility and increases sensitivity of the detection of changes in flow. Real-time, automatic tracing of the Doppler flow profile allows beat-to-beat right-sided and left-sided Q measurements, simplifying operation and reducing

2145-399: The Stewart-Hamilton principle. Lithium chloride dilution uses a peripheral vein and a peripheral arterial line. Like PiCCO, frequent calibration is recommended when there is a change in Q. Calibration events are limited in frequency because they involve the injection of lithium chloride and can be subject to errors in the presence of certain muscle relaxants. The PulseCO algorithm used by LiDCO

2210-484: The UK's National Institute for Health and Clinical Excellence ( NICE ). Oesophageal Doppler monitoring measures the velocity of blood and not true Q , therefore relies on a nomogram based on patient age, height and weight to convert the measured velocity into stroke volume and cardiac output. This method generally requires patient sedation and is accepted for use in both adults and children. Pulse pressure (PP) methods measure

2275-483: The arterial PP waveform. In both cases, an independent technique is required to provide calibration of continuous Q analysis because arterial PP analysis cannot account for unmeasured variables such as the changing compliance of the vascular bed. Recalibration is recommended after changes in patient position, therapy or condition. In PiCCO, transpulmonary thermodilution, which uses the Stewart-Hamilton principle but measures temperatures changes from central venous line to

2340-452: The body's cells and removes cellular waste. Because it pumps out whatever blood comes back into it from the venous system , the quantity of blood returning to the heart effectively determines the quantity of blood the heart pumps out – its cardiac output, Q . Cardiac output is classically defined alongside stroke volume (SV) and the heart rate (HR) as: In standardizing what CO values are considered to be within normal range independent of

2405-427: The cardiac cycle. Lower impedance indicates greater intrathoracic fluid volume and blood flow. By synchronizing fluid volume changes with the heartbeat, the change in impedance can be used to calculate stroke volume, cardiac output and systemic vascular resistance. Both invasive and non-invasive approaches are used. The reliability and validity of the non-invasive approach has gained some acceptance, although there

2470-423: The case of heart failure , actual CO may be insufficient to support even simple activities of daily living; nor can it increase sufficiently to meet the higher metabolic demands stemming from even moderate exercise. Cardiac output is a global blood flow parameter of interest in hemodynamics , the study of the flow of blood. The factors affecting stroke volume and heart rate also affect cardiac output. The figure at

2535-463: The circulated oxygen consumed (VO 2 ) per minute through metabolism varies depending on the activity level but at rest is circa 25% of the DO 2 . Physical exercise requires a higher than resting-level of oxygen consumption to support increased muscle activity. Regular aerobic exercise can induce physiological adaptations such as improved stroke volume and myocardial efficiency that increase cardiac output. In

2600-591: The code for Kovilpatti railway station , Tamil Nadu Organisations [ edit ] Christelijke Volkspartij , Belgian political party, later renamed Christen-Democratisch en Vlaams (CD&V) Christlichdemokratische Volkspartei der Schweiz, the Christian Democratic People's Party of Switzerland Christian People's Party (disambiguation) , multiple parties in Germany Business [ edit ] Corporación Venezolana de Petroleo ,

2665-411: The considered gold standard methods in stable condition and in various haemodynamic states. It can be used to monitor pediatric and mechanically supported patients. Generally monitored haemodynamic values, fluid responsiveness parameters and an exclusive reference are provided by PRAM: Cardiac Cycle Efficiency (CCE). It is expressed by a pure number ranging from 1 (best) to -1 (worst) and it indicates

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2730-474: The data pairs SV and SVV has been published. Arterial monitoring systems are unable to predict changes in vascular tone; they estimate changes in vascular compliance. The measurement of pressure in the artery to calculate the flow in the heart is physiologically irrational and of questionable accuracy, and of unproven benefit. Arterial pressure monitoring is limited in patients off-ventilation, in atrial fibrillation, in patients on vasopressors, and in those with

2795-489: The device from application in patients without vasoconstriction, such as in sepsis or in patients on vasopressors. In 1978, scientists at BMI-TNO, the research unit of Netherlands Organisation for Applied Scientific Research at the University of Amsterdam , invented and patented a series of additional key elements that make the volume clamp work in clinical practice. These methods include the use of modulated infrared light in

2860-457: The establishment of an extracorporeal circulation through its unique AV loop with two pre-existing arterial and central venous lines in ICU patients. When the saline indicator is injected into the AV loop, it is detected by the venous clamp-on sensor on the loop before it enters the patient's heart's right atrium. After the indicator traverses the heart and lung, the concentration curve in the arterial line

2925-530: The flow volume per beat ( stroke volume , SV). The result is then multiplied by the heart rate (HR) to obtain cardiac output. Although used in clinical medicine, it has a wide test-retest variability. It is said to require extensive training and skill, but the exact steps needed to achieve clinically adequate precision have never been disclosed. 2D measurement of the aortic valve diameter is one source of noise; others are beat-to-beat variation in stroke volume and subtle differences in probe position. An alternative that

2990-484: The heart and the blood vessels, thus limiting their application for measurement of Q . This can be partially compensated for by intermittent calibration of the waveform to another Q measurement method then monitoring the PP waveform. Ideally, the PP waveform should be calibrated on a beat-to-beat basis. There are invasive and non-invasive methods of measuring PP. In 1967, the Czech physiologist Jan Peňáz invented and patented

3055-472: The implantable flow probe. This accuracy has ensured high levels of clinical use in conditions including sepsis, heart failure and hypertension. The Transoesophageal Doppler includes two main technologies; transoesophageal echocardiogram —which is primarily used for diagnostic purposes, and oesophageal Doppler monitoring—which is primarily used for the clinical monitoring of cardiac output. The latter uses continuous wave Doppler to measure blood velocity in

3120-427: The left ventricle of the heart via the aorta and arteries. Oxygen delivery (DO 2 mL/min) is the resultant of blood flow (cardiac output CO) times the blood oxygen content (CaO 2 ). Mathematically this is calculated as follows: oxygen delivery = cardiac output × arterial oxygen content, giving the formula: With a resting cardiac output of 5 L/min, a 'normal' oxygen delivery is around 1 L/min. The amount/percentage of

3185-426: The mean velocity by the cross-sectional area of the vessel. This flow data can be used in a flow-versus-time graph. The area under the flow-versus-time curve for one cardiac cycle is the stroke volume. The length of the cardiac cycle is known and determines heart rate; Q can be calculated using equation ( 1 ). MRI is typically used to quantify the flow over one cardiac cycle as the average of several heart beats. It

3250-541: The measuring point during the subinterval from t = t i − 1 {\displaystyle t=t_{i-1}} to t = t i {\displaystyle t=t_{i}} is: ( c o n c e n t r a t i o n ) ( v o l u m e ) = c ( t i ) ( F Δ t ) {\displaystyle (concentration)(volume)=c(t_{i})(F\Delta t)} where F {\displaystyle F}

3315-509: The optical system inside the sensor, the lightweight, easy-to-wrap finger cuff with velcro fixation, a new pneumatic proportional control valve principle, and a set point strategy for the determining and tracking the correct volume at which to clamp the finger arteries—the Physiocal system. An acronym for physiological calibration of the finger arteries, this Physiocal tracker was found to be accurate, robust and reliable. The Finapres methodology

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3380-400: The overall heart-vascular response coupling. The ratio between heart performance and consumed energy, represented as CCE "stress index", can be of paramount importance in understanding the patient's present and future courses. Impedance cardiography (often abbreviated as ICG, or Thoracic Electrical Bioimpedance (TEB)) measures changes in electrical impedance across the thoracic region over

3445-407: The pressure in an artery over time to derive a waveform and use this information to calculate cardiac performance. However, any measure from the artery includes changes in pressure associated with changes in arterial function, for example compliance and impedance. Physiological or therapeutic changes in vessel diameter are assumed to reflect changes in Q . PP methods measure the combined performance of

3510-443: The proximal aortic site, the 3-element Windkessel model of this impedance can be modelled with sufficient accuracy in an individual patient with known age, gender, height and weight. According to comparisons of non-invasive peripheral vascular monitors, modest clinical utility is restricted to patients with normal and invariant circulation. Invasive PP monitoring involves inserting a manometer pressure sensor into an artery—usually

3575-423: The right margin illustrates this dependency and lists some of these factors. A detailed hierarchical illustration is provided in a subsequent figure . There are many methods of measuring CO, both invasively and non-invasively; each has advantages and drawbacks as described below. The function of the heart is to drive blood through the circulatory system in a cycle that delivers oxygen, nutrients and chemicals to

3640-403: The same term [REDACTED] This disambiguation page lists articles associated with the title CVP . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=CVP&oldid=1215818822 " Category : Disambiguation pages Hidden categories: Short description

3705-556: The shape of said waveforms, the effect of vascular tone is assessed, allowing the calculation of SV. Q is then derived using equation ( 1 ). Only perfused beats that generate an arterial waveform are counted for in HR. This system estimates Q using an existing arterial catheter with variable accuracy. These arterial monitors do not require intracardiac catheterisation from a pulmonary artery catheter. They require an arterial line and are therefore invasive. As with other arterial waveform systems,

3770-521: The short set-up and data acquisition times are benefits of this technology. Disadvantages include its inability to provide data regarding right-sided heart pressures or mixed venous oxygen saturation. The measurement of Stroke Volume Variation (SVV), which predicts volume responsiveness is intrinsic to all arterial waveform technologies. It is used for managing fluid optimisation in high-risk surgical or critically ill patients. A physiologic optimization program based on haemodynamic principles that incorporates

3835-489: The size of the subject's body, the accepted convention is to further index equation ( 1 ) using body surface area (BSA), giving rise to the Cardiac index (CI). This is detailed in equation ( 2 ) below. There are a number of clinical methods to measure cardiac output, ranging from direct intracardiac catheterization to non-invasive measurement of the arterial pulse. Each method has advantages and drawbacks. Relative comparison

3900-475: The stroke volume would be approximately 70 mL. Because cardiac output is related to the quantity of blood delivered to various parts of the body, it is an important component of how efficiently the heart can meet the body's demands for the maintenance of adequate tissue perfusion . Body tissues require continuous oxygen delivery which requires the sustained transport of oxygen to the tissues by systemic circulation of oxygenated blood at an adequate pressure from

3965-451: The symbols Q {\displaystyle Q} , Q ˙ {\displaystyle {\dot {Q}}} , or Q ˙ c {\displaystyle {\dot {Q}}_{c}} , is the volumetric flow rate of the heart 's pumping output: that is, the volume of blood being pumped by a single ventricle of the heart, per unit time (usually measured per minute). Cardiac output (CO)

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4030-435: The thermodilution curve and giving measurements of cardiac filling volumes ( GEDV ), intrathoracic blood volume and extravascular lung water. Transpulmonary thermodilution allows for less invasive Q calibration but is less accurate than PA thermodilution and requires a central venous and arterial line with the accompanied infection risks. In LiDCO, the independent calibration technique is lithium chloride dilution using

4095-403: The time of acquisition compared to conventional echocardiography. USCOM has been validated from 0.12 L/min to 18.7 L/min in new-born babies, children and adults. The method can be applied with equal accuracy to patients of all ages for the development of physiologically rational haemodynamic protocols. USCOM is the only method of cardiac output measurement to have achieved equivalent accuracy to

4160-460: Was developed to use this information to calculate arterial pressure from finger cuff pressure data. A generalised algorithm to correct for the pressure level difference between the finger and brachial sites in patients was developed. This correction worked under all of the circumstances it was tested in—even when it was not designed for it—because it applied general physiological principles. This innovative brachial pressure waveform reconstruction method

4225-476: Was first implemented in the Finometer, the successor of Finapres that BMI-TNO introduced to the market in 2000. The availability of a continuous, high-fidelity, calibrated blood pressure waveform opened up the perspective of beat-to-beat computation of integrated haemodynamics, based on two notions: pressure and flow are inter-related at each site in the arterial system by their so-called characteristic impedance. At

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