How to use echocardiography to manage patients with shock? / ¿Cuál es la utilidad de la ecocardiografía en el shock?

Echocardiography enables the intensivist to assess the patient with circulatory failure. It allows the clinician to identify rapidly the type and the cause of shock in order to develop an effective management strategy. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied. Early and repeated echocardiography is a valuable tool for the management of shock in the intensive care unit. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. The four core types of shock (cardiogenic, hypovolemic, obstructive, and septic) can readily be identified by echocardiography. Echocardiography can differentiate the different pathologies that may be the cause of each type of shock. More importantly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock, which emphasises on the added value of transthoracic echocardiography (TTE) in such population of patients. In this review we aimed to provide to clinicians a bedside strategy of the use of TTE parameters to manage patients with shock. In the first part of this overview, we detailed the different TTE parameters and how to use them to identify the type of shock. And in the second part, we focused on the use of these parameters to evaluate the effect of treatments, in different types of shock. (AU)

La ecocardiografía permite al intensivista valorar al paciente con fallo circulatorio agudo. Esta técnica ayuda a identificar, rápidamente y de una manera no invasiva, el tipo y la causa del shock para instaurar una estrategia terapéutica. La realización de exámenes ecocardiográficos precoces y repetidos es una valiosa herramienta para el manejo del shock en la unidad de cuidados intensivos. La mayoría de patologías responsables del shock pueden ser identificadas con un nivel básico de ecocardiografía en 2D y modo M. En la actualidad, las competencias en ecocardiografía básica se consideran mandatorias en la formación de los profesionales de Medicina Intensiva. Los cuatro tipos básicos de shock (cardiogénico, hipovolémico, obstructivo y séptico) pueden ser adecuadamente identificados con la ecocardiografía. Además, la ecografía puede diferenciar las diferentes patologías que pueden ser la causa de cada uno de los tipos de shock. Es importante señalar que, dada la complejidad y la edad avanzada de muchos pacientes críticos, el shock puede ser multifactorial (p.ej.: combinación de shock séptico y cardiogénico), lo que enfatiza el valor añadido de la ecocardiografía transtorácica (ETT) en esta población de pacientes. En esta revisión, queremos proporcionar a los clínicos una estrategia, a pie de cama, del uso de los parámetros obtenidos con la ETT para manejo de los pacientes en shock. En la primera parte de este artículo, se detallan los diferentes parámetros ecocardiográficos y cómo pueden utilizarse para identificar los tipos de shock. En la segunda parte, se expone el uso de estos parámetros para evaluar el efecto de los tratamientos en los diferentes tipos de shock. (AU)

The Use of Point-of-Care Ultrasound to Evaluate Pulsus Paradoxus in Children With Asthma.

Pulsus paradoxus (PP) is defined as a fall of systolic blood pressure of greater than 10 mm Hg during the inspiratory phase of respiration. Measurement of PP is recommended by national and international asthma guidelines as an objective measure of asthma severity but is rarely used in clinical practice. Cardiac point-of-care ultrasound with pulsed wave Doppler imaging measuring respiratory-phasic changes of mitral valve inflow velocities is well described in cardiac tamponade as "sonographic" PP. We present 10 cases of acute asthma presenting to an emergency department showing the finding of sonographic determined PP in the apical 4-chamber view of the heart on pulsed wave Doppler imaging.

Intervendor Discordance of Fetal and Neonatal Myocardial Tissue Doppler and Speckle-Tracking Measurements.

BACKGROUND: Fetal and neonatal studies report a wide range of cardiac parameters derived by pulsed-wave Doppler tissue imaging (DTI) and two-dimensional speckle-tracking echocardiographic (STE) imaging. The use of different ultrasound systems and their vendor-specific software compromises the ability to compare echocardiographic findings among various studies. The aim of this study was to evaluate intervendor reproducibility as well as intra- and interobserver repeatability of DTI and STE measurements in normal-term fetuses and neonates. METHODS: A prospective study was conducted of term fetuses (n = 196) from uncomplicated pregnancies assessed days before the onset of labor and a few hours after birth. Fetal and neonatal DTI and STE parameters were obtained and analyzed using vendor-specific software on three ultrasound systems: Toshiba Aplio MX versus GE Vivid E9 and GE Vivid E9 versus Philips EPIQ. A reproducibility study in fetuses and neonates (n = 118) was performed by systematic scanning with head-to-head comparison. RESULTS: DTI reproducibility showed moderate to good correlation, with good agreement for fetuses and neonates on Toshiba versus GE (intraclass correlation coefficient [ICC] = 0.4-0.8). Correlation of DTI measurements on GE versus Philips was poor to moderate for fetuses (ICC = 0.1-0.6) and moderate to good for neonates (ICC = 0.5-0.8), with wider limits of agreement. Fetal and neonatal STE parameters revealed very poor correlation (ICC = 0.1-0.3) and agreement among ultrasound vendors. Intra- and interobserver repeatability demonstrated good to excellent correlation of all fetal and neonatal DTI and STE measurements, with good agreement irrespective of the ultrasound platform used. CONCLUSIONS: These findings demonstrate reliable assessment of fetal and neonatal DTI and STE measurements when performed on the same ultrasound platform, whereas ultrasound machines and software from different vendors give significantly divergent estimates of DTI and STE parameters in fetuses and neonates. These intervendor discrepancies have significant clinical and research implications and should be considered when interpreting and comparing study findings, establishing reference standards, or performing systematic reviews.

Prognostic Value of a Simple Echocardiographic Parameter, the Right Ventricular Systolic to Diastolic Duration Ratio, in Patients with Advanced Heart Failure with Non-Ischemic Dilated Cardiomyopathy.

The prognostic value of the right ventricular (RV) systolic to diastolic duration ratio (S/D ratio) in patients with advanced heart failure is not clear.We enrolled 45 patients with DCM (40 ± 13 years, 33 male) who were admitted to our hospital for evaluation or treatment of heart failure. The RV systolic and diastolic durations were measured using continuous Doppler imaging of tricuspid regurgitation, and the RV S/D ratio was calculated. Cardiac events were defined as cardiac death or left ventricular assist device implantation within the first year. Twenty-eight cardiac events occurred. The RV S/D ratio was significantly higher in the event group than in the event-free group (1.8 ± 0.8 versus 1.2 ± 0.5, P = 0.008). Univariate analysis showed that the RV S/D ratio, plasma brain natriuretic peptide concentration, left atrial volume index, and mitral deceleration time were associated with these events. Receiver operating characteristic curve analysis revealed that the optimal RV S/D cutoff value to predict events was 1.2 (sensitivity 79%, specificity 65%, area under the curve 0.745). Kaplan-Meier analysis indicated a significantly higher event rate in patients with an RV S/D ratio > 1.2 (log-rank test, P = 0.003). The addition of an RV S/D ratio > 1.2 improved the prognostic utility of a model that included conventional variables (P = 0.014).In patients with advanced heart failure with DCM, the RV S/D ratio was higher in patients with events than in those without events. The addition of the RV S/D ratio to conventional parameters may provide better prognostic information.

Dynamic fetal cardiovascular magnetic resonance imaging using Doppler ultrasound gating.

BACKGROUND: Fetal cardiovascular magnetic resonance (CMR) imaging may provide a valuable adjunct to fetal echocardiography in the evaluation of congenital cardiovascular pathologies. However, dynamic fetal CMR is difficult due to the lack of direct in-utero cardiac gating. The aim of this study was to investigate the effectiveness of a newly developed Doppler ultrasound (DUS) device in humans for fetal CMR gating. METHODS: Fifteen fetuses (gestational age 30-39 weeks) were examined using 1.5 T CMR scanners at three different imaging sites. A newly developed CMR-compatible DUS device was used to generate gating signals from fetal cardiac motion. Gated dynamic balanced steady-state free precession images were acquired in 4-chamber and short-axis cardiac views. Gating signals during data acquisition were analyzed with respect to trigger variability and sensitivity. Image quality was assessed by measuring endocardial blurring (EB) and by image evaluation using a 4-point scale. Left ventricular (LV) volumetry was performed using the single-plane ellipsoid model. RESULTS: Gating signals from the fetal heart were detected with a variability of 26 ± 22 ms and a sensitivity of trigger detection of 96 ± 4%. EB was 2.9 ± 0.6 pixels (4-chamber) and 2.5 ± 0.1 pixels (short axis). Image quality scores were 3.6 ± 0.6 (overall), 3.4 ± 0.7 (mitral valve), 3.4 ± 0.7 (foramen ovale), 3.6 ± 0.7 (atrial septum), 3.7 ± 0.5 (papillary muscles), 3.8 ± 0.4 (differentiation myocardium/lumen), 3.7 ± 0.5 (differentiation myocardium/lung), and 3.9 ± 0.4 (systolic myocardial thickening). Inter-observer agreement for the scores was moderate to very good (kappa 0.57-0.84) for all structures. LV volumetry revealed mean values of 2.8 ± 1.2 ml (end-diastolic volume), 0.9 ± 0.4 ml (end systolic volume), 1.9 ± 0.8 ml (stroke volume), and 69.1 ± 8.4% (ejection fraction). CONCLUSION: High-quality dynamic fetal CMR was successfully performed using a newly developed DUS device for direct fetal cardiac gating. This technique has the potential to improve the utility of fetal CMR in the evaluation of congenital pathologies.

Evaluation of a Portable Doppler Ultrasound Gating Device for Fetal Cardiac MR Imaging: Initial Results at 1.5T and 3T.

PURPOSE: Fetal cardiac MRI has the potential to play an important role in the assessment of fetal cardiac pathologies, but it is up to now not feasible due to a missing gating method. The purpose of this work was the evaluation of Doppler ultrasound (DUS) for external fetal cardiac gating with regard to compatibility, functionality, and reliability. Preliminary results were assessed performing fetal cardiac MRI. METHODS: An MRI conditional DUS device was developed to obtain a gating signal from the fetal heart. The MRI compatibility was evaluated at 1.5T and 3T using B1 field maps and gradient echo images. The quality and sensitivity of the DUS device to detect the fetal heart motion for cardiac gating were evaluated outside the MRI room in 15 fetuses. A dynamic fetal cardiac phantom was employed to evaluate distortions of the DUS device and gating signal due to electromagnetic interferences at 1.5T and 3T. In the first in vivo experience, dynamic fetal cardiac images were acquired in four-chamber view at 1.5T and 3T in two fetuses. RESULTS: The maximum change in the B1 field and signal intensity with and without the DUS device was <6.5% for 1.5T and 3T. The sensitivity of the DUS device to detect the fetal heartbeat was 99.1%. Validation of the DUS device using the fetal cardiac phantom revealed no electromagnetic interferences at 1.5T or 3T and a high correlation to the simulated heart frequencies. Fetal cardiac cine images were successfully applied and showed good image quality. CONCLUSION: An MR conditional DUS gating device was developed and evaluated revealing safety, compatibility, and reliability for different field strengths. In a preliminary experience, the DUS device was successfully applied for in vivo fetal cardiac imaging at 1.5T and 3T.

Incremental value of right atrial strain for early diagnosis of hemodynamic deterioration in pulmonary hypertension: a new noninvasive tool for a more comprehensive diagnostic paradigma.

AIMS: Increased right atrial size is related to adverse prognosis in pulmonary hypertension. The potential incremental value of right atrial function assessment is still unclear. We tested the relationship between right atrial two-dimensional speckle-tracking echocardiography impairment and hemodynamic, functional and clinical deterioration in patients with pulmonary hypertension. METHODS: We prospectively evaluated 36 patients (27 female, 9 male; mean age 68 ±â€Š13 years) with suspected pulmonary hypertension undergoing right heart catheterization and 16 matched controls. All patients underwent baseline evaluation by New York Heart Association functional class, 6-min walking test, brain natriuretic peptide (BNP), and standard two-dimensional echocardiography in less than 48 h of right heart catheterization. Right atrial two-dimensional speckle-tracking echocardiography was assessed by averaging all segments in standard four-chamber apical view. RESULTS: Right atrial global integral strain was significantly lower in patients compared with controls (11.40 ±â€Š5.22% vs. 25.72 ±â€Š5.95 P < 0.001). Moreover, right atrial global strain, but not right atrial area or volume, was correlated with invasively measured cardiac index (CI) (r = 0.72; P < 0.0001) and pulmonary vascular resistances in all patients, even though stronger in subjects with precapillary pulmonary hypertension (r = -0.42, P = 0.018; r = -0.54, P = 0.007 respectively; P = 0.007). It was also correlated with New York Heart Association (P = 0.027), BNP (P = 0.002), and 6-min walking test (P = 0.006). After multivariate analysis including right atrial volume, tricuspid annular plane systolic excursion, left atrial strain, and BNP, right atrial global strain showed the strongest correlation with CI. Area under the curve optimal cutoff for predicting CI at least 2.4 l/min/m was 17% (area under the curve: 0.83, sensitivity: 90%, specificity: 54%). CONCLUSION: Right atrial global strain can identify right atrial functional impairment before structural changes and may be implemented in a comprehensive, noninvasive right heart assessment for diagnosis and follow-up of pulmonary hypertension patients.

Identification of the main determinants of abdominal aorta size: a screening by Pocket Size Imaging Device.

BACKGROUND: Ultrasound exam as a screening test for abdominal aorta (AA) can visualize the aorta in 99% of patients and has a sensitivity and specificity approaching 100% in screening settings for aortic aneurysm. Pocket Size Imaging Device (PSID) has a potential value as a screening tool, because of its possible use in several clinical settings. Our aim was to assess the impact of demographics and cardiovascular (CV) risk factors on AA size by using PSID in an outpatient screening. METHODS: Consecutive patients, referring for a CV assessment in a 6 months period, were screened. AA was visualized by subcostal view in longitudinal and transverse plans in order to determine the greatest anterior-posterior diameter. After excluding 5 patients with AA aneurysm, 508 outpatients were enrolled. All patients underwent a sequential assessment including clinical history with collection of CV risk factors, physical examination, PSID exam and standard Doppler echoc exam using a 2.5 transducer with harmonic capability, both by expert ultrasound operators, during the same morning. Standard echocardiography operators were blinded on PSID exam and viceversa. RESULTS: Diagnostic accuracy of AA size by PSID was tested successfully with standard echo machine in a subgroup (n = 102) (rho = 0.966, p < 0.0001). AA diameter was larger in men than in women and in ≥50 -years old subjects than in those <50 -years old (both p < 0.0001). AA was larger in patients with coronary artery disease (CAD) (p < 0.0001). By a multivariate model, male sex (p < 0.0001), age and body mass index (both p < 0.0001), CAD (p < 0.01) and heart rate (p = 0.018) were independent predictors of AA size (cumulative R 2 = 0.184, p < 0.0001). CONCLUSION: PSID is a reliable tool for the screening of determinants of AA size. AA diameter is greater in men and strongly influenced by aging and overweight. CAD may be also associated to increased AA diameter.

Piocele como complicación de peritonitis en un preescolar / Pyocele as a complication peritonitis in an preschooler

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Cambios hemodinámicos en la exploración mediante eco-doppler tras angioplastia con stent de arteria renal nativa / Haemodynamic changes in duplex ultrasound after native renal artery stenting

OBJETIVOS: Describir los cambios hemodinámicos que se producen en el ecodoppler tras una angioplastia con stent de arteria renal (AR) nativa. PACIENTES Y MÉTODOS: Se analizaron retrospectivamente todas las angioplastias sobre AR nativa realizadas entre los años 2000 y 2013, seleccionando aquellos casos con: 1) ecodoppler durante los 6 meses previos y posteriores al procedimiento, 2) angioplastia con stent de una AR con permeabilidad de la contralateral. Se compararon mediante el test de Wilcoxon las velocidades en el origen de ambas AR y la ratio renoaórtica (RAR), antes y después del procedimiento. RESULTADOS: Setenta y un casos (40%) cumplieron los criterios de inclusión. En las arterias tratadas, la velocidad media disminuyó significativamente un 56% tras el procedimiento (341 vs. 164 cm/s; p < 0,00). En un 73% de estas AR, las velocidades postangioplastia disminuyeron al rango de la normalidad (<200 cm/s). En las AR contralaterales (no tratadas), la velocidad media también disminuyó significativamente un 13% (199 vs. 175 cm/s; p = 0,029). Tras la angioplastia disminuyó de 41 a 33% el porcentaje de AR contralaterales con velocidad por encima del valor normal (>200 cm/s). La RAR también mostró una disminución estadísticamente significativa en la AR tratada (4,13 vs. 1,87; p < 0,000) como en la no tratada (2,71 vs. 2,28; p < 0,026). CONCLUSIONES: En la exploración ecodoppler tras una angioplastia con stent renal se produce una disminución significativa de las velocidades en el origen de ambas AR, la tratada y la no tratada. Este último hallazgo indica la existencia de una aceleración vicariante en la arteria no tratada, que disminuye cuando se corrige la lesión

OBJECTIVES: To describe the haemodynamic changes in duplex ultrasound after angioplasty and stenting of the native renal artery (RA). PATIENTS AND METHODS: All native RA angioplasties performed between 2000 and 2013 were retrospectively analysed, selecting those cases: 1) Duplex ultrasound within 6 months before and after the procedure, 2) unilateral renal artery angioplasty and stenting with patency of the contralateral RA. The flow velocities at the origin of the treated and untreated RA, and the renal aortic ratio (RAR), were compared using the Wilcoxon test before and after the procedure. RESULTS: Seventy-one cases (40%) satisfied the inclusion criteria, all of them without significant residual stenosis after the procedure. In the treated arteries, the mean velocity decreased significantly by 56% after the procedure (341 vs. 164 cm/s; P<.00). The post-angioplasty flow velocity in 73% of these RAs decreased to within the normal range (<200 cm/s). The mean velocity in contralateral RAs (untreated) also significantly decreased by 13% (199 vs. 175 cm/s; P<.029). After angioplasty, the percentage of contralateral RAs with velocity above normal (>200 cm/s) fell from 41 to 33%. The RAR also showed a statistically significant decrease in the treated RA (413 vs. 1.87; P<.000) and untreated RA (2.71 vs. 2.28; P<.026). CONCLUSIONS: Duplex ultrasound after renal angioplasty and stenting produced a significant decrease in the flow velocity at the origin of both the treated and untreated RAs. The latter finding suggests the existence of a vicarious acceleration in the untreated renal artery, which decreases when correcting the lesion

Participants' above-chance recognition of own-heart sound combined with poor metacognitive awareness suggests implicit knowledge of own heart cardiodynamics.

Mounting evidence suggests that interoceptive signals are fundamentally important for the experience of the self. Thus far, studies on interoception have mainly focused on the ability to monitor the timing of ongoing heartbeats and on how these influence emotional and self-related processes. However, cardiac afferent signalling is not confined to heartbeat timing and several other cardiac parameters characterize cardiodynamic functioning. Building on the fact that each heart has its own self-specific cardio-dynamics, which cannot be expressed uniquely by heart rate, we devised a novel task to test whether people could recognize the sound of their own heart even when perceived offline and thus not in synchrony with ongoing heartbeats. In a forced-choice paradigm, participants discriminated between sounds of their own heartbeat (previously recorded with a Doppler device) versus another person's heart. Participants identified the sound of their own heart above chance, whereas their metacognition of performance - as calculated by contrasting performance against ratings of confidence - was considerably poorer. These results suggest an implicit access to fine-grained neural representations of elementary cardio-dynamic parameters beyond heartbeat timing.

Edema laterocervical izquierdo recurrente en paciente joven / Recurrent left laterocervical swelling in a young patient

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Punciones transtorácicas guiadas con ecografía / No disponible

La ecografía transtorácica es una técnica de gran utilidad para guiar punciones. Presenta ventajas sobre otras, como el TAC y la fluoroscopia. El mayor beneficio que el neumólogo puede encontrar en ella es la accesibilidad de la técnica y la visión en tiempo real de la aguja. Como cualquier otra, requiere de una curva de aprendizaje, que es perfectamente asumible por los neumólogos que se dedican a realizar técnicas neumológicas

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Valoración de la presión pulmonar y su repercusión sobre cavidades derechas por ecocardiografía / No disponible

El presente capítulo tiene como objetivo acercar al neumólogo el conocimiento de la ecocardiografía como herramienta fundamental para la estimación de parámetros hemodinámicos de indudable importancia para el agnóstico, la estratificación del riesgo y el manejo terapéutico de la hipertensión pulmonar (HTP) y el tromboembolismo pulmonar (TEP). En general, estas mediciones ecocardiográficas muestran una excelente correlación con la hemodinámica y los métodos empleados no son excesivamente complejos, estando al alcance de cualquier profesional con un tiempo de adiestramiento muy razonable. Este texto trata de explicar, de forma gráfica y sencilla, los distintos métodos empleados en ecocardiografía para cuantificar la presión pulmonar y las resistencias vasculares pulmonares. La ecocardiografía valora, además, las repercusiones que la HTP y el TEP ejercen sobre las cavidades derechas en su intento de adaptación, permitiéndonos analizar los principales parámetros de morfología y función ventricular derecha, que han demostrado tener un valor pronóstico en estas patologías

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In vitro evaluation of an ultrasonic cardiac output monitoring (USCOM) device.

Non-invasive cardiac output monitoring techniques provide high yield, low risk mechanisms to identify and individually treat shock in the emergency setting. The non-invasive ultrasonic cardiac output monitoring (USCOM) device uses an ultrasound probe applied externally to the chest; however limitations exist with previous validation strategies. This study presents the in vitro validation of the USCOM device against calibrated flow sensors and compares user variability in simulated healthy and septic conditions. A validated mock circulation loop was used to simulate each condition with a range of cardiac outputs (2-10 l/min) and heart rates (50-95 bpm). Three users with varying degrees of experience using the USCOM device measured cardiac output and heart rate by placing the ultrasound probe on the mock aorta. Users were blinded to the condition, heart rate and cardiac output which were randomly generated. Results were reported as linear regression slope (ß). All users estimated heart rate in both conditions with reasonable accuracy (ß = 0.86-1.01), while cardiac output in the sepsis condition was estimated with great precision (ß = 1.03-1.04). Users generally overestimated the cardiac output in the healthy simulation (ß = 1.07-1.26) and reported greater difficulty estimating reduced cardiac output compared with higher values. Although there was some variability between users, particularly in the healthy condition (P < 0.01), all estimations were within a clinically acceptable range. In this study the USCOM provided a suitable measurement of cardiac output and heart rate when compared with our in vitro system. It is a promising technique to assist with the identification and treatment of shock.

Comparison of Two Different Ultrasound Systems for the Evaluation of Tissue Doppler Velocities in Fetuses.

INTRODUCTION: Recent studies have reported variations of up to 30% between different ultrasound machines for tissue Doppler imaging (TDI), a problem that can significantly impact clinical diagnosis, patient management and research studies. The objective of this study was to assess repeatability and agreement between fetal myocardial peak velocities evaluated by TDI with two different ultrasound systems. MATERIALS AND METHODS: Systolic (S'), early (E') and late (A') diastolic myocardial peak velocities at mitral and tricuspid annuli as well as at the basal septum were evaluated by spectral TDI in 150 fetuses using two different ultrasound systems: Siemens Antares (Siemens Medical Systems, Malvern, Pa., USA) and Vivid Q (General Electric Healthcare, Horten, Norway). A method comparison study was performed, calculating intraclass correlation coefficients (ICC), and agreement was assessed by Bland-Altman plots. RESULTS: Annular peak velocities showed lower values when measured by Vivid Q compared to values measured by Siemens Antares. ICC ranged from 0.07 (septal S') to 0.33 (right A'), showing very poor repeatability for clinical application. Agreement between the two systems was also poor, with high coefficients of variation for all measurements. CONCLUSIONS: Fetal annular peak velocities obtained with different ultrasound systems are not directly comparable. This is consistent with previous data in adults and warrants the need of system-specific reference values, suggesting that the same ultrasound machine should be used for longitudinal follow-up.

The effect of aorta unfolding and remodelling on oesophageal Doppler readings as probe depth is varied.

BACKGROUND: The thoracic aorta elongates and unfolds with advancing age. Lateral displacement and tortuosity of the descending part may affect oesophageal Doppler monitoring (ODM) readings because probe alignment becomes slanted. This investigation aimed to relate aortic displacement as it appears on the chest radiograph with variations in ODM readings as the probe is inserted to different depths. METHODS: In anaesthetized patients a series of three to five ODM stroke volume (SV) readings were obtained at insertion depths of 35-45 cm during stable haemodynamics. The coefficient of variation (CV=standard deviation/mean %) was calculated. The degree of descending aorta unfolding was measured by (i) lateral displacement (LD), that is, the difference in the maximum and minimum distances between the midline and para-aortic line; and (ii) curvature angle (CA), the angle formed by a tangential line from the intersection of the para-aortic line and the diaphragm to its curve with the vertical line. RESULTS: Data from 70 patients were analysed. The median CV of SV readings was 14% (range 4-48). Variation between ODM readings, shown by the CV of SV readings, increased linearly with aortic unfolding: R2=0.44 for LD and R2=0.60 for CA. Patients with a CA ≤15° were younger and had significantly lower CVs of ODM readings than those with a CA >15° (P=0.001). Age and hypertension was associated with increased CA. CONCLUSIONS: Increased lateral displacement and tortuosity of the descending aorta reduces the reliability of ODM measurements as probe depth is varied, especially with aging.