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P Vignon

Publications and source records attributed to P Vignon.

46 records · Page 3Linked to original sources

Diagnostic accuracy and therapeutic impact of transthoracic and transesophageal echocardiography in mechanically ventilated patients in the ICU.

STUDY OBJECTIVES: To assess the respective diagnostic accuracy of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) and their therapeutic implications in mechanically ventilated patients, in the intensive care unit (ICU). DESIGN: A prospective study. SETTINGS: Intensive care units of two tertiary referral teaching hospitals. PATIENTS: One hundred eleven ICU patients (81 men and 30 women; mean age 57 +/- 16 years). Fifty-seven percent were hospitalized for medical illnesses, 16.5 percent after thoracic surgery, 10.5 percent after other surgery, and 16.0 percent for multiple trauma. Their Simplified Acute Physiologic Score was 16 +/- 5. INTERVENTIONS: The echocardiograms were performed in order to solve well-defined clinical problems. TTE was the first step of the procedure and TEE was performed only when (1) TTE did not solve the clinical problems, and (2) TTE yielded unsuspected findings requiring TEE. During each echocardiographic study, the following were noted: ventilatory mode, clinical problems, imaging quality, results, consequence on acute care, duration of the procedure, and potential complications of TEE. Diagnostic accuracy was defined as the proportion of solved problems, and therapeutic impact was defined as changes on acute care that resulted directly from the procedure. MEASUREMENTS AND RESULTS: One hundred twenty-eight consecutive TTE and 96 TEE were performed. TTE solved 60 of 158 clinical problems (38 percent), whether positive end-expiratory pressure (> 4 cm H2O) was present or not (28 of 74 vs 32 of 84: p > 0.50). TTE allowed evaluation of left ventricular function in 77 percent of cases and pericardial effusion in every case, but it did not solve most of the other clinical problems. Indeed, the diagnostic accuracy of TEE was markedly superior (95/98 vs 60/158: p < 0.001), but TEE required a physician's presence longer (43 +/- 17 min vs 27 +/- 12 min: p < 0.001). When TTE and TEE were scheduled (n = 96), TEE yielded an additional diagnosis or excluded with more certitude a suspected diagnosis, except in two cases. TEE had a therapeutic impact more frequently than TTE (35/96 vs 20/128: p < 0.001). Cardiovascular surgery was prompted by echocardiographic findings in ten patients. TEE was well tolerated in all patients; there were no complications. CONCLUSIONS: TEE is a valuable well-tolerated imaging technique in mechanically ventilated patients. For the assessment of left ventricular systolic function and pericardial effusion; however, TTE continues to be an excellent diagnostic tool, even when positive end-expiratory pressure is present. Both TTE and TEE have a therapeutic impact in approximately 25 percent of cases.

Echocardiography↗

[Diagnostic value of transesophageal echocardiography in traumatic rupture of the thoracic aorta].

Traumatic rupture of the aorta (TRA) usually occurs at the isthmus. It is rapidly lethal without early surgery and, therefore, diagnosis must not be delayed. The reference diagnostic investigation is aortography but it is invasive in a patient with multiple trauma whose haemodynamic status is often precarious. Transoesophageal echocardiography, a non-invasive investigation which can be undertaken rapidly at the bedside has been proposed recently for the diagnosis of this condition because it gives excellent views of the aortic isthmus. The authors report their experience of transoesophageal echocardiography in 3 victims of severe road traffic accidents with thoracic trauma and who were operated for traumatic rupture of the aorta. Echocardiographic diagnosis of TRA is based on the recording of the association of a thick and mobile intraluminal echo corresponding to the torn intima and media and localised dilatation of the aorta, the wall of which is reduced to the adventitia under tension. On Doppler colour flow mapping the velocities are similar on both sides of the tear but turbulence at the site of rupture may give rise to aliasing. It is important to recognise the echocardiographic features of TRA to differentiate it from dissection of the aorta. Transoesophageal echocardiography also allows diagnosis of any associated traumatic cardiovascular lesions. Its limitations are due to the inability to visualise the proximal portion of the transverse aorta and the supra aortic vessels. Aortography remains essential when a lesion of these vessels is suspected and when the echocardiographic features of the aorta are atypical.

Accidents, Traffic↗

[Failure and complications of transesophageal echocardiography. Apropos of 1500 consecutive cases].

Transesophageal echocardiography (TEE) requires the introduction of a flexible probe into the oesophagus and therefore cannot be strictly considered to be non-invasive. This manipulation exposes the patient to complications which are benign in the large majority of cases. The authors report their experience in a prospective study analysing the failures and complications of TEE in the first 1,500 cases performed in their laboratory between May 1988 and May 1992, in mainly adult and ambulatory patients. The probe could not be introduced in 24 patients (1.6%), including 5 cases during the initial learning period. No serious complications were observed during of after TEE. Minor incidents were noted in 28 cases (1.9%) intolerance of the probe (12 cases), nausea and/or vomiting (4 cases), dyspnea (4 cases) due to tracheal intubation in 2 patients, laryngeal in 1 patient and to cardiac failure in 1 case. Pharyngeal haemorrhage (2 cases), atrial fibrillation (3 cases), vertigo (1 case), mandibular dislocation (1 case) and salivary hypersecretion affecting the quality of the imaging (1 case), were also observed. The investigation had to be interrupted prematurely in 12 cases (0.8%) usually because of intolerance of the probe. These results show that TEE is not dangerous in trained hands. Failure to introduce the probe is usually encountered during the learning period, which reinforces the need for apprenticeship in a teaching center. The safety of this technique, plus its considerable diagnostic value in many clinical indications, justify its present role in everyday cardiological practice.

Atrial Fibrillation↗

Acute hypoxia decreases cardiac response to catecholamines in exercising humans.

Cardiac chronotropic response to adrenergic activity at rest and exercise has been studied in 8 sea-level natives on the first two days of exposure to high altitude hypoxia (3823 m, 473 mmHg). Maximal O2 uptake (VO2max) was determined at low altitude (day 0:D0) and high altitude (day 2:D2). Submaximal exercise tests were performed at low altitude (day 1:D1) and high altitude (days 3 and 4: D3, D4). Plasma venous norepinephrine (NE) and epinephrine (E) concentrations were determined at rest and at the end of submaximal exercise. From D0 to D2, maximal heart rate decreased by 7% (p less than 0.01), and VO2max decreased by 17% (p less than 0.01). During submaximal exercise, plasma NE did not vary significantly (D1: 1.36 +/- 0.57, D3: 1.48 +/- 0.51, D4: 1.31 +/- 0.54 ng.ml-1). In contrast, relative work load decreased at high altitude (% VO2max at D1, D3 and D4 were respectively: 90.2 +/- 6.1, 83.3 +/- 9.8, 76.9 +/- 8.2). Linear relationships were found, both at low and high altitudes, between NE and VO2, NE and % VO2max, and between the increases in NE and heart rate during exercise. Covariance analysis indicates that these relations shifted to the left at high altitude:for the same NE or increase in NE, VO2 or increase in heart rate was lower at high altitude. Variations in E were similar but not significant. We conclude that hypoxia induced a decrease in cardiac chronotropic response to adrenergic activation during submaximal exercise.

Adult↗

[Normalization of the dimensions of the left ventricle as measured by echocardiography].

An M mode echocardiographic study was performed, of left ventricular dimensions and wall thickness in two series of normal (N1, N2) and pathological (P1, P2) subjects. In the more recent series (N2 = 40, P2 = 17) data acquisition was facilitated by tests deduced from the technique of ultrasound transit time. The parameters compared were based on: 1) the proportionality between fractional shortening and fractional thickening (N1: not significant; N2: p less than 0.001), 2) the relationship between systolic radius and wall thickness (linear correlation, r = 0.95, between N2 and P2). The slope seemed to be related to the initial condition of contraction, the ratio of end diastolic wall thickness/radius (N1: p less than 0.01). There are several ways of normalising myocardial surface of section in adults and children; the normal surface is related to body surface area (r = 0.87; p less than 0.001 between calculated and predicted values for a N2 mean of 9.3 +/- 0.06 cm2/m2). The end diastolic diameters and wall thicknesses correlated with body surface area but the coefficients were not as statistically significant due to physiological variations in chamber filling. The indexed myocardial surface was increased (p less than 0.001) in the pathological series. The introduction of these tests improves the reliability of echocardiographic data. The use of several measurements simultaneously allows normalisation of body surface area and increases the diagnostic efficacy.

Echocardiography↗

Contrast echocardiographic quantification of regional myocardial perfusion: validation with an isolated rabbit heart model.

Quantification of regional myocardial tissue blood flow (RMBF) based on contrast echocardiography has yet to be achieved. This study validated our recently proposed algorithm for quantification of RMBF with colored microspheres. Experiments were carried out in an isolated rabbit heart preparation (n = 11). Aortic root injections of perfluoropropane-filled albumin microsphere solution (FS069) and colored microspheres were performed at five levels of coronary flow achieved by altering perfusion pressure. During each injection of contrast material, consecutive end-diastolic images of the heart and an extracardiac reference chamber were acquired with a 7.5 MHz transducer and digitized. Time-intensity curves from the reference chamber and myocardial regions of interest, corresponding to the anatomic segments used for colored microsphere analysis, were analyzed for RMBF. Blood flow was calculated as the intravascular volume fraction (ratio of areas under myocardial and reference curves) divided by mean transit time (deconvolution of impulse response) and compared with those obtained with colored microspheres. Injections of FS069 resulted in highly reproducible enhancement of myocardial contrast. Analysis of time-intensity curves provided consistent measurements of RMBF (r = 0.91), which correlated highly with microsphere data (r = 0.84). The use of this new algorithm allows accurate quantification of RMBF in the isolated heart model. Further validation of this approach in an animal model with peripheral intravenous injections of contrast material will allow noninvasive clinical measurements of RMBF.

Albumins↗

Acute limb ischemia and heparin-induced thrombocytopenia: the value of echocardiography in eliminating a cardiac source of arterial emboli.

We report an unusual thromboembolic event occurring during severe heparin-induced thrombocytopenia. A left intraventricular thrombus was diagnosed as the source of multiple arterial emboli, resulting in an initial cerebrovascular event and subsequent bilateral acute lower extremity ischemia requiring emergency surgery. No underlying heart disease was detected. Pathologic examination of the embolectomy specimen revealed fibrin platelet aggregates with rare white and red blood cells, consistent with a "white thrombus." We conclude that routine monitoring of platelet count should be performed in all patients receiving heparin to identify promptly individuals who have heparin-induced thrombocytopenia, and when thromboembolic complications occur in this setting, echocardiography is indicated to identify possible intracardiac sources for emboli, even in patients with previously known structurally intact hearts.

Dose-Response Relationship, Drug↗

Quantitative assessment of average velocity in inferior vena cava by phase-display MR imaging: pulsed Doppler correlation.

A technique for measuring average velocity in the inferior vena cava (IVC) by using phase-display magnetic resonance (MR) imaging is described. Fifteen healthy subjects were imaged, and the velocities and spectra obtained by MR were compared with pulsed Doppler results. Distortions of the "zebra-striped" images obtained along the axis of the vessel were measured at the same level of the IVC as in pulsed Doppler. Measurements of average velocities in the IVC made by the two methods were very similar, and velocity curves obtained during the cardiac cycle were superimposable. Phase-display MR imaging has the potential to noninvasively assess blood flow in large vessels as accurately as pulsed Doppler.

Adult↗

A new simple technique for the insertion of cuffed central venous catheters: an initial experience.

BACKGROUND: Although tunneled polyurethane catheters with polyester cuffs are useful when prolonged central venous access is necessary but their insertion still remains challenging at times. We report the first study of a new cuffed polyurethane catheter (Seldicuff) that can be easily inserted using the Seldinger technique without the need of a vein dilator and that incorporates a tunneling needle onto the catheter. A Seldicuff catheter was placed in 15 patients (mean age: 53 +/- 11 years) who required prolonged parenteral nutrition. All catheters were inserted into the right subclavian vein. The procedure lasted 6.4 +/- 0.8 minutes and no complication directly related to catheter placement was noted. Catheters remained in position for a mean duration of 103 days (range, 58 to 220 days). During this period, no infectious or mechanical complications were observed. CONCLUSION: These results demonstrate that placement of this novel cuffed catheter is as simple as inserting a conventional central venous catheter.

Catheterization, Central Venous↗