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Biomedical subjects

S Prin

Publications and source records attributed to S Prin.

7 recordsLinked to original sources
PubMed2001

The Internal jugular veins are asymmetric. Usefulness of ultrasound before catheterization.

OBJECTIVE: To demonstrate an asymmetry of the internal jugular veins, a finding which will have consequences for catheterization. DESIGN: Prospective study. SETTING: The medical ICU of a university-affiliated teaching hospital. PATIENTS: Eighty critically ill consecutive patients. INTERVENTION: Measurement of the cross-sectional area of the internal jugular veins. Search for an asymmetry, defined as an area at least twice that of the contralateral vein. RESULTS: An asymmetry was noted in 62.5% of the patients. The dominant vein was the right in only 68 % of these cases. In addition, 23% of the 160 jugular internal veins had an area of 0.4 cm2 or less. CONCLUSIONS: Using a simple technique, ultrasound identifies the dominant internal jugular vein, thus indicating the safer side before blind catheterization.

Catheterization, Central Venous↗
PubMed2001

Acute cor pulmonale in massive pulmonary embolism: incidence, echocardiographic pattern, clinical implications and recovery rate.

OBJECTIVE: The indications for the use of thrombolytic agents in massive pulmonary embolism (MPE) remain controversial and it has been suggested that transthoracic echocardiographic (TTE) examination, which is able to detect an associated right ventricular dysfunction, may cast light on this question. The goal of this study was to examine the incidence of acute cor pulmonale (ACP) in MPE, diagnosed on the basis of TTE criteria, its clinical implications and its resolution rate. DESIGN: Ten-year retrospective clinical study. SETTING: A medical and a coronary intensive care unit, university hospital. PATIENTS: One hundred sixty-one patients with proven MPE. INTERVENTIONS: Acute cor pulmonale was defined as right ventricular end-diastolic area / left ventricular end-diastolic area (RVEDA/LVEDA) ratio in the long axis greater than 0.6 associated with septal dyskinesia in the short axis. ACP patients were divided into three groups according to circulatory status: 32 patients without circulatory failure constituted group 1, 32 patients with circulatory failure requiring inotropic support, but free of metabolic acidosis, constituted group 2 and 34 patients in whom circulatory failure was associated with metabolic acidosis (defined by a base deficit >5 mEq/l) constituted group 3. RESULTS: Acute cor pulmonale was present in 61% of patients with MPE and carried a 23% mortality, but this mortality was very different in stable patients (groups 1 and 2, 64 patients, 3% mortality) and in unstable patients (group 3, 34 patients, 59% mortality). A multivariate logistic regression analysis showed that the TTE results were not predictive of the risk of death. Conversely, the same analysis showed that the presence of metabolic acidosis was a powerful predictor of death. CONCLUSION: Because none of the TTE measurements in ACP could be used to stratify the severity of MPE, TTE was of no help in deciding on medical thrombolysis. However, depending on its severity, metabolic acidosis could justify a large cooperative study to assess the impact of thrombolytic therapy on mortality rate in this specific group.

Acidosis↗
PubMed2001

Early preload adaptation in septic shock? A transesophageal echocardiographic study.

BACKGROUND: An accepted concept in septic shock is that preload adaptation by acute left ventricular dilatation, when occurring spontaneously or with the aid of volume loading, permits maintenance of an adequate cardiac output, leading to final recovery. From a physiologic point of view, this concept appears debatable because a normal pericardium exerts a restraining action on a normal heart. METHODS: During a 26-month period, the authors investigated, by transesophageal echocardiography, 40 patients hospitalized in their unit for an episode of septic shock. Transesophageal echocardiography was performed in the first hours after admission, proceeded by correction of any hypovolemia, and stabilization of arterial pressure by vasoactive agent infusion if necessary. Left ventricular dimensions were obtained in long- and short-axis views, permitting calculation of left ventricular ejection fraction (long axis) and fractional area contraction (short axis). Stroke index was simultaneously measured by the Doppler technique. RESULTS: Stroke index was strongly correlated with both echocardiographic left ventricle ejection fraction (r = 0.75; P < 0.0001) and left ventricle fractional area contraction (r = 0.76; P < 0.0001), whereas it was independent of echocardiographic left ventricle diastolic dimensions. CONCLUSIONS: The transesophageal echocardiography study was unable to confirm the reality of the concept of early preload adaptation by left ventricular dilatation in septic shock. Conversely, because left ventricular volume always remained in a normal range after correcting hypovolemia, systolic function was the unique determinant of stroke index in septic shock.

Adult↗
PubMed2001

Influence of superior vena caval zone condition on cyclic changes in right ventricular outflow during respiratory support.

BACKGROUND: Adequate fluid resuscitation in critically ill patients undergoing mechanical ventilation remains a difficult challenge, and diastolic and systolic right ventricular (RV) changes produced by positive airway pressure are important to consider in an individual patient with inadequate circulatory adaptation during respiratory support. We hypothesized that insufficient thoracic vena cava filling, predisposing to inspiratory collapse (zone 2 condition), may transiently affect RV outflow. METHODS: We measured beat-to-beat superior vena caval diameter and Doppler RV outflow during a routine transesophageal echocardiographic examination in 22 patients undergoing mechanical ventilation, all of whom required hemodynamic monitoring, and we calculated a collapsibility index for the superior vena cava as maximal expiratory diameter minus minimal inspiratory diameter, divided by maximal expiratory diameter. RESULTS: In 15 patients (group 1), the collapsibility index was low (17 +/- 7%) and was associated with a moderate inspiratory decrease in RV outflow (25 +/- 17%). However, in seven patients (group 2), we observed a high collapsibility index (71 +/- 7%), which was associated with a major inspiratory decrease in RV outflow (69 +/- 14%) combined with a reduced pulmonary artery flow period. A rapid volume expansion, only performed on group 2, markedly and significantly reduced both the collapsibility index (15 +/- 12%) and the inspiratory decrease in RV outflow (31 +/- 20%). CONCLUSION: A major inspiratory decrease in RV outflow associated with a reduced pulmonary artery flow period in a patient undergoing mechanical ventilation reflected a high collapsibility index of the thoracic vena cava, suggesting a zone 2 condition, and may be corrected by blood volume expansion.

Aged↗
PubMed2001

Positive end-expiratory pressure titration in acute respiratory distress syndrome patients: impact on right ventricular outflow impedance evaluated by pulmonary artery Doppler flow velocity measurements.

OBJECTIVE: Positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome patients remains debatable. We used two mechanical approaches, calculation of the compliance of the respiratory system and determination of the lower inflexion point of the pressure-volume curve of the respiratory system, to identify specific PEEPs (PEEPS and PEEPA) whose impact on right ventricular (RV) outflow was compared with Doppler analysis of pulmonary artery flow velocity. DESIGN: Prospective, open, clinical study. SETTING: Medical intensive care unit of a university hospital. PATIENTS: Sixteen consecutive ventilator-dependent acute respiratory distress syndrome patients. INTERVENTIONS: Two PEEPs were determined: PEEPS was the highest PEEP associated with the highest value of respiratory compliance, and PEEPA was the coordinate of the lower inflexion point of the inspiratory pressure-volume curve on the pressure axis plus 2 cm H2O. MEASUREMENTS AND MAIN RESULTS: We observed a large difference between the two PEEPs, with PEEPA (13 + 4 cm H2O) > PEEPS (6 + 3 cm H2O). Changes in RV outflow impedance produced by tidal ventilation with zero end-expiratory pressure (ZEEP) and after application of these two PEEPs were assessed by Doppler study of pulmonary artery flow velocity obtained by a transesophageal approach, with particular reference to the end-expiratory and end-inspiratory pulmonary artery velocity-time integral, as reflecting RV stroke output, and mean acceleration as reflecting RV outflow impedance during an unchanged flow period. A significant inspiratory reduction in pulmonary artery velocity-time integral (from 11.8 + 0.3 to 10.0 + 0.3 cm) and mean acceleration (from 11.9 + 0.9 to 8.0 + 0.9 m/sec2) was observed with ZEEP, showing a reduction in RV stroke index (from 29.0 + 0.9 to 26.0 + 0.6 cm3/m2) by a sudden increase in outflow impedance during tidal ventilation. Application of PEEPA, which improved Pao2 (102 + 40 vs. 65 + 18 torr with ZEEP), worsened the inspiratory drop in RV stroke index (21.6 + 0.8 cm3/m2), resulting in a significant reduction in cardiac index compared with ZEEP (from 3.0 + 1.0 to 2.7 + 1.1). Application of PEEPS, which also significantly improved Pao2 (81 + 21 torr), was associated with a lesser impact on RV outflow impedance (inspiratory mean acceleration: 9.5 + 1 m/sec2) and cardiac index (3.2 + 1.0) than PEEPA. CONCLUSION: RV outflow impedance evaluated by the Doppler technique appeared sensitive to PEEP titration. Application of PEEPA worsened RV systolic function impairment produced by tidal ventilation. Conversely, application of PEEPS reduced RV systolic function impairment, suggesting an association with a lower pulmonary vascular resistance.

Analysis of Variance↗
PubMed2001

Acute cor pulmonale in acute respiratory distress syndrome submitted to protective ventilation: incidence, clinical implications, and prognosis.

CONTEXT: The incidence of acute cor pulmonale (ACP), a frequent and usually lethal complication of acute respiratory distress syndrome (ARDS) during traditional respiratory support, has never been re-evaluated since protective ventilation gained acceptance. OBJECTIVE: We performed a longitudinal transesophageal echocardiographic (TEE) study to determine whether this incidence, and its severe implications for prognosis, might have changed in our unit as we altered respiratory strategy. DESIGN: Prospective open clinical study. SETTING: Medical intensive care unit of a university hospital. PATIENTS: Seventy-five consecutive ARDS patients given respiratory support with airway pressure limitation (plateau pressure < or =30 cm H2O). INTERVENTIONS: ACP was defined as a ratio of right ventricular end-diastolic area to left ventricular end-diastolic area in the long axis >0.6 associated with septal dyskinesia in the short axis during TEE examination. RESULTS: Normal right ventricular function was present in 56 patients, whereas right ventricular dysfunction was observed in 19 patients after 2 days of respiratory support. ACP was associated with pulmonary artery hypertension, increased heart rate, and decreased stroke index. Significant impairment of left ventricular diastolic function was also seen. All echo-Doppler abnormalities were reversible in patients who recovered, and the mortality rate was the same in both groups (32%). However, ACP patients who recovered required a longer period of respiratory support. A multivariate analysis individualized Paco2 level as the sole factor independently associated with ACP, suggesting that ACP development in ARDS is influenced by the severity of lung damage and/or the respiratory strategy. CONCLUSION: Evaluation of right ventricular function by TEE in a group of 75 ARDS patients submitted to protective ventilation revealed the persistence of a 25% incidence of ACP, resulting in detrimental hemodynamic consequences associated with tachycardia. However, ACP was reversible in patients who recovered and did not increase mortality.

APACHE↗