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Biomedical subjects

Pierre Couture

Publications and source records attributed to Pierre Couture.

At least 19 recordsLinked to original sources
PubMed2006

Importance of relative pulmonary hypertension in cardiac surgery: the mean systemic-to-pulmonary artery pressure ratio.

OBJECTIVE: To determine the importance of the mean arterial pressure-to-mean pulmonary artery pressure ratio (MAP/MPAP) in cardiac surgical patients. DESIGN: Retrospective and prospective studies (3 groups). SETTING: Tertiary care hospital. PARTICIPANTS: Cardiac surgical patients (1,557). INTERVENTION: Retrospective analysis (group 1), induction of general anesthesia (group 2), and transesophageal Doppler echocardiography (group 3). MEASUREMENTS AND MAIN RESULTS: In group 1 (n = 1,439), demographic, hemodynamic, and other perioperative variables were collected with follow-up until hospital discharge. The primary outcome was a composite index of hemodynamic complications that included death, resuscitated cardiac arrest, use of vasopressive drugs for >24 hours postoperatively, or the use of an intra-aortic balloon pump that was not present preoperatively. In group 2 (n = 34), the effect of general anesthesia on the MAP/MPAP ratio was studied, and Doppler echocardiography was used to evaluate diastolic profiles in group 3 (n = 74). In group 1, a total of 302 patients experienced hemodynamic complications (21%). The MAP/MPAP ratio was significantly lower in the patients who developed complications (3.3 +/- 1.3 v 4.0 +/- 1.4, p < 0.0001). Multiple stepwise logistic regression analysis showed the MAP/MPAP ratio to be an independent predictor of hemodynamic complications (p < 0.0001). In group 2, the induction of anesthesia decreased both MAP and MPAP, but the ratio remain unchanged (p = 0.242). In group 3, patients with moderate-to-severe diastolic dysfunction (DD) had a lower ratio (3.5 +/- 0.9 v 4.0 +/- 1.1 compared with those with normal-to-mild DD, p = 0.07). CONCLUSION: The MAP/MPAP ratio is a useful hemodynamic variable in cardiac surgery. It can be used to predict hemodynamic complications after cardiac surgery, is not influenced by the induction of anesthesia, and tends to correlate with the severity of left ventricular diastolic profiles.

Aged↗
PubMed2006

Left and right ventricular diastolic dysfunction as predictors of difficult separation from cardiopulmonary bypass.

PURPOSE: As the evaluation of diastolic function can be complex in the setting of a busy cardiac operating room, its assessment may benefit from an algorithmic approach using transesophageal echocardiography. We developed a diagnostic algorithm which was then applied in a series of cardiac surgery patients to determine whether moderate to severe left ventricular diastolic dysfunction (LVDD) and right ventricular diastolic dysfunction (RVDD) can predict difficult separation from cardiopulmonary bypass (DSB). METHODS: An algorithm using pulsed-wave Doppler interrogation of the mitral and tricuspid valve, the pulmonary and hepatic venous flow, and tissue Doppler interrogation of the mitral and tricuspid annulus was developed. The study was divided in two phases involving two groups of patients undergoing cardiac surgery. In phase I, echocardiographic evaluations of patients (n = 74) were used to test the reproducibility of the algorithm and to evaluate inter-observer variability using Cohen's kappa values which were calculated in three specific periods. In phase II, the algorithm was applied to a second group of patients (validation group, n = 179) to explore its prognostic significance. The primary end-point in phase II was DSB. RESULTS: In phase I, the kappa coefficients for LVDD and RVDD algorithms were 0.77 and 0.82, respectively. In phase II, moderate or severe degrees of LVDD were observed in 29 patients (16%) and moderate to severe RVDD was observed in 18 patients (10%) before cardiac surgery. Both moderate and severe LVDD (P = 0.017) and RVDD (P = 0.049) before surgery were observed more frequently in patients with DSB. CONCLUSION: Moderate and severe LVDD and RVDD can be identified with very good reproducibility, and both degrees of diastolic dysfunction are associated with DSB.

Aged↗
PubMed2006

Dynamic quantitative echocardiographic evaluation of mitral regurgitation in the operating department.

Hemodynamic modifications induced by general anesthesia could lead to underestimation of mitral regurgitation (MR) severity in the operating department and potentially serious consequences. The intraoperative severity of MR was prospectively compared with the preoperative baseline evaluation using dynamic quantitative transesophageal echocardiography in 25 patients who were stable with MR 2/4 or greater undergoing coronary bypass, mitral valve operation, or both. Significant changes in the severity of MR using transesophageal echocardiographic criteria occurred after the induction of general anesthesia and with phenylephrine. Quantitative transesophageal echocardiographic evaluation of MR using effective orifice area and vena contracta, and the use of phenylephrine challenge, were useful to avoid underestimating MR severity in the operating department.

Adolescent↗
PubMed2006

Biventricular diastolic filling patterns after coronary artery bypass graft surgery.

OBJECTIVE: We sought to study the evolution of biventricular filling properties after coronary artery bypass grafting. BACKGROUND: The evolution of diastolic function as defined with newer echocardiographic modalities after coronary artery bypass grafting surgery is unknown in patients with preoperative left ventricular diastolic dysfunction. METHODS: Transthoracic echocardiography was performed preoperatively and 48 hours and 6 months after coronary artery bypass grafting in 49 patients (randomized to milrinone [n = 25]) or placebo [n = 24]) with preoperative left ventricular diastolic dysfunction classified according to published criteria. Mild right ventricular diastolic dysfunction was defined as the ratio of early to atrial filling velocity of less than 1 in transtricuspid flow or the velocity of reversed atrial flow of greater than 50% of that of systolic flow in hepatic venous flow or the ratio of tricuspid annulus velocity during early and atrial filling of less than 1 if both the ratio of early to atrial filling velocity and the ratio of systolic to diastolic velocity was greater than 1 in hepatic venous flow. Moderate right ventricular diastolic dysfunction was diagnosed when there was a ratio of early to atrial filling velocity of greater than 1 with a ratio of systolic to diastolic velocity of less than 1. Severe right ventricular diastolic dysfunction was defined as a ratio of early to atrial filling velocity of greater than 1 associated with reversed systolic wave in hepatic venous flow. RESULTS: Moderate and severe left ventricular diastolic dysfunction increased from preoperatively to 48 hours after coronary artery bypass grafting from 8.2% to 53.7% and from 2.0% to 9.7%, respectively (P < .0001, 48 hours vs preoperatively for both), and the patterns at 6 months were similar to those observed preoperatively. Similar evolution over time was found for right ventricular diastolic dysfunction. CONCLUSIONS: In patients with preoperative left ventricular diastolic dysfunction, biventricular filling patterns are impaired initially but return to preoperative status 6 months after coronary artery bypass grafting.

Aged↗
PubMed2006

Dynamic right ventricular outflow tract obstruction in cardiac surgery.

BACKGROUND: Right ventricular outflow tract obstruction can be a cause of hemodynamic instability but it has not been described in non-congenital cardiac surgery. METHODS: The prevalence of right ventricular outflow tract obstruction was retrospectively studied in 670 consecutive patients undergoing cardiac surgery. Significant right ventricular outflow tract obstruction was diagnosed if the right ventricular systolic to pulmonary artery peak gradient was more than 25 mm Hg. The diagnosis was based on measurement of the right ventricular and pulmonary artery systolic pressure through the paceport and distal opening of the pulmonary artery catheter. To further validate the prevalence and the importance of right ventricular outflow tract obstruction, 130 patients were prospectively studied over a 12-month period. RESULTS: In the retrospective cohort, 6 patients (1%) undergoing various types of cardiac surgical procedures were found to have significant dynamic right ventricular outflow tract obstruction with a mean gradient of 31 +/- 4 mm Hg (26 to 35 mm Hg). In the prospective study significant dynamic right ventricular outflow tract obstruction was identified in 5 patients (4%) (average peak: 37 +/- 15 mm Hg; range: 27 to 60 mm Hg). The typical transesophageal echocardiography finding was end-systolic obliteration of the right ventricular outflow tract. In patients with significant dynamic right ventricular outflow tract obstruction, hemodynamic instability was present in 10/11 patients (91%). CONCLUSIONS: Right ventricular outflow tract obstruction is easily diagnosed using the paceport of the pulmonary artery catheter and should be considered as a potential cause of hemodynamic instability especially when transesophageal echocardiography reveals systolic right ventricular cavity obliteration.

Aged↗
PubMed2006

Inhaled milrinone: a new alternative in cardiac surgery?

The administration of milrinone through inhalation has been studied in only a few animal and human studies. Compared to the intravenous administration, inhaled milrinone has been shown to reduce pulmonary artery pressure without systemic hypotension. Therefore, this approach could represent an alternative to nitric oxide. This current state of knowledge of intravenous and inhaled milrinone is presented and summarized.

Administration, Inhalation↗
PubMed2005

Esophageal Doppler and thermodilution are not interchangeable for determination of cardiac output.

PURPOSE: This study compares thermodilution cardiac output (TD-CO) and esophageal Doppler cardiac output (ED-CO) during periods of hemodynamic stability and after heart stabilization during off-pump coronary artery bypass (OPCAB) surgery. METHODS: After Institutional Review Board approval, 58 patients undergoing OPCAB had simultaneous comparison of TD-CO and ED-CO at three time periods. Measurements were recorded, in a blinded manner, after probe insertion (T0), immediately before and after (T1,T2) heart displacement and before starting any pharmacological treatment (if needed) to maintain systolic blood pressure to its value before heart mobilization. Measurements were also taken before sternal closure (Tfinal). RESULTS: Three hundred and two pairs of data were analyzed using the Bland and Altman method. Bias, standard deviation (SD) of the bias (precision), and degree of agreement (bias +/- 2 SD) were calculated. Based on published literature, we considered that the highest degree of agreement should be < 0.5 L.min(-1) to consider both methods as interchangeable. At T0, bias and SD of bias between TD-CO and ED-CO were -0.1 +/- 1.0 L.min(-1). Immediately before heart stabilization, bias +/- SD was 0.6 +/- 1.0 L.min(-1) and after heart displacement, 0.5 +/- 0.8 L.min(-1). At Tfinal, bias +/- SD was 0.7+/- 0.7 L.min(-1). CONCLUSION: Because the degree of agreement was > 0.5 L.min(-1) at all measurement periods except T0, we conclude that TD and ED are not interchangeable at any time during OPCAB surgery.

Aged↗
PubMed2005

Incidence and significance of abnormal hepatic venous Doppler flow velocities before cardiac surgery.

OBJECTIVE: The purpose of this study was to determine the incidence and significance of abnormal hepatic Doppler venous flow velocities as signs of an abnormal right ventricular filling pattern before cardiac surgery. DESIGN: Retrospective and prospective validation study. SETTING: Tertiary care hospital. PARTICIPANTS: Cardiac surgical patients (121 patients). INTERVENTIONS: Not applicable. MEASUREMENTS: Demographic, hemodynamic, and echocardiographic variables; vasoactive support; and difficult separation from bypass were compared between patients with or without abnormal hepatic venous Doppler flow. Logistic regression analysis was performed to identify predictors of difficult separation from bypass. Abnormal hepatic venous flow was observed in 23 (29%) and 17 patients (41%) in the retrospective and prospective study. Abnormal hepatic venous flow before surgery was associated with more vasoactive support in both the retrospective (p = 0.0362) and prospective study (p = 0.0163). In the prospective study, abnormal hepatic venous flow was associated with a higher Parsonnet score (p = 0.0005), more atrial fibrillation (p < 0.0001), pacemaker requirement (p = 0.0124), mitral valve replacement (p = 0.0325), reoperation (p = 0.0050), lower mean arterial pressure to pulmonary artery pressure ratio (p = 0.0127), higher wall motion score index (p = 0.0491), and higher incidence of abnormal right ventricular systolic function (p = 0.0139). Abnormal hepatic venous flow was not found to be an independent predictor of difficult separation from bypass. CONCLUSIONS: Abnormal hepatic venous flow velocities before cardiac surgery are frequent and are associated with increased need for vasoactive support after cardiopulmonary bypass. However, it is not an independent predictor of difficult separation from bypass and worse outcome.

Aged↗
PubMed2004

Poor correlation between hemodynamic and echocardiographic indexes of left ventricular performance in the operating room and intensive care unit.

OBJECTIVES: To compare hemodynamic and echocardiographic indexes of left ventricular performance. DESIGN: Retrospective database analysis of four clinical trials. SETTING: University hospital. PATIENTS: Cardiac surgery patients. INTERVENTION: Left ventricular performance was evaluated using left ventricular stroke work index (LVSWI) calculated from the pulmonary artery catheter and both fractional area change and regional wall motion score index (RWMSI) measured from transesophageal echocardiography. Measures of left ventricular performance were obtained before and after bypass (group 1, n = 30), during acute increase and decrease in preload (group 2, n = 14), after administration of inhaled prostacyclin or placebo in patients with pulmonary hypertension (group 3, n = 20), and in hemodynamically unstable patients in the intensive care unit at admission and at 2 and 4 hrs (group 4, n = 20). MAIN RESULTS: A total of 186 simultaneous LVSWI, fractional area change, and RWMSI were analyzed and compared. Patients with RWMSI <1.3 had a LVSWI of 23.4 +/- 10.3 g.m.m compared with 18.4 +/- 7.2 g.m.m in those with RWMSI >1.3 (p =.0349). Subdividing fractional area change into three different groups (> or =50%, 25% to 49%, and < or =24%), the corresponding values of LVSWI were 22.3 +/- 9.7 g.m.m, 22.2 +/- 10.8 g.m.m, and 17.7 +/- 5.5 g.m.m, respectively (p =.5114). Correlations between LVSWI and RWMSI changes ranged from -0.28 to 0.16 (p values from.31 to.94). Correlations between LVSWI and fractional area change changes ranged from -0.62 to 0.22 (p values from.07 to.95). CONCLUSION: There is a significant discrepancy and limited relationship between the hemodynamic and echocardiographic evaluation of left ventricular performance.

Analysis of Variance↗
PubMed2003

Partial inferior vena cava snaring to control ischemic left ventricular dysfunction.

PURPOSE: To describe the hemodynamic and intraoperative transesophageal echocardiographic evaluation of cardiac systolic and diastolic function in a patient undergoing off-pump coronary artery bypass graft (OP-CABG) surgery who developed pulmonary artery hypertension controlled by inferior vena cava (IVC) snaring. CLINICAL FEATURES: A 63-yr-old man was referred to our hospital for elective OP-CABG surgery. His preoperative ventriculopathy revealed a decreased systolic function (ejection fraction of 35%), and a mild mitral regurgitation. Intraoperatively, after application of the stabilizer and clamping of the diagonal artery, he developed a marked increase in pulmonary artery pressure (PAP) with a decrease in systemic arterial pressure, non responsive to iv norepinephrine and nitroglycerin. Transesophageal echocardiographic evaluation revealed a marked decrease in systolic function and presence of a restrictive diastolic filling pattern. Partial IVC snaring decreased the venous return and PAP decreased cardiac chamber dimensions, improved systolic function and improved diastolic filling pattern. CONCLUSION: Partial IVC snaring was used successfully to treat a hemodynamically unstable patient with sudden increase in PAP caused by ischemic left ventricular failure during OP-CABG.

Coronary Artery Bypass↗
PubMed2003

Transesophageal echocardiography monitoring in the intensive care department: the management of hemodynamic instability secondary to thoracic tamponade after single lung transplantation.

A 65-year-old woman with pulmonary fibrosis had hemodynamic instability develop after single lung transplantation. Transesophageal echocardiography was useful in determining the cause of hemodynamic instability, which was secondary to thoracic tamponade. Furthermore, transesophageal echocardiography monitoring was important in the decision to initiate extracorporeal membrane oxygenation to evaluate adequate positioning of the cannula and in the extracorporeal membrane oxygenation weaning process.

Aged↗
PubMed2003

Inhaled epoprostenol (prostacyclin) and pulmonary hypertension before cardiac surgery.

OBJECTIVE: Pulmonary hypertension is commonly found in patients undergoing valvular surgery and can be worsened by cardiopulmonary bypass. Inhaled epoprostenol (prostacyclin) has been used for the treatment of pulmonary hypertension, but its effects compared with those of placebo on hemodynamics, oxygenation, echocardiographic examination, and platelet function have not been studied during cardiac surgery. METHODS: Twenty patients with pulmonary hypertension undergoing cardiac surgery were randomized in a double-blind study to receive inhaled epoprostenol (60 microg) or placebo. The inhalation occurred after induction of anesthesia and before surgical incision. The effects on left and right systolic and diastolic cardiac functions evaluated by means of pulmonary artery catheterization and transesophageal echocardiography, as well as oxygenation and platelet aggregation, were studied. RESULTS: Inhalation of epoprostenol significantly reduced indexed right ventricular stroke work from 10.7 +/- 4.57 g. m. m(-2) to 7.8 +/- 3.94 g. m. m(-2) (P =.003) and systolic pulmonary artery pressure from 48.4 +/- 18 mm Hg to 38.9 +/- 11.9 mm Hg (P =.002). The effect was correlated with the severity of pulmonary hypertension (r = 0.76, P =.01) and was no longer apparent after 25 minutes. There was no significant effect on systemic arterial pressures, left ventricular function, arterial oxygenation, platelet aggregation, and surgical blood loss. CONCLUSION: Inhaled epoprostenol reduces pulmonary pressure and improves right ventricular stroke work in patients with pulmonary hypertension undergoing cardiac surgery. A dose of 60 microg is hemodynamically safe, and its effect is completely reversed after 25 minutes. We did not observe any evidence of platelet dysfunction or an increase in surgical bleeding after administration of inhaled epoprostenol.

Administration, Inhalation↗
PubMed2002

Mechanisms of hemodynamic changes during off-pump coronary artery bypass surgery.

PURPOSE: To describe the mechanisms of hemodynamic changes during off-pump coronary artery bypass graft surgery (OP-CABG). SOURCE: Pertinent medical literature in the English and French languages was identified through a Medline computerized literature search and a manual search of selected articles, using off-pump coronary artery surgery, beating heart surgery, hemodynamic, and transesophageal echocardiography as key words. Human and animal studies were included. PRINCIPAL FINDING: Hemodynamic variations in OP-CABG may be due to mobilization and stabilization of the heart, or myocardial ischemia occurring during coronary occlusion. Suction type and compression type stabilizers produce hemodynamic effects through different mechanisms. Heart dislocation (90 degrees anterior displacement) and compression of the right ventricle to a greater extent than the left ventricle are responsible for hemodynamic alterations when using suction type stabilizers. Compression of the left ventricular outflow tract and abnormal diastolic expansion secondary to direct deformation of the left ventricular geometry are proposed mechanisms for hemodynamic derangements with compression type stabilizer. Coronary occlusion during the anastomosis can have additional effects on left ventricular function, depending on the status of collateral flow. The value and limitations of electrocardiographic (ECG), hemodynamic and echocardiographic monitoring modalities during OP-CABG are reviewed. CONCLUSIONS: In summary, hemodynamic changes which can either be secondary to the stabilization technique or to transient ischemia represent an important diagnostic challenge during off-bypass procedures. The mechanism can vary according to the stabilization system. Current monitoring such as ECG and hemodynamic monitoring are used but remain limited in establishing the cause of hemodynamic instability. Transesophageal echocardiography is used in selected patients to diagnose the etiology of hemodynamic instability and can direct therapy, particularly in those with severe myocardial systolic and diastolic dysfunction, mild to moderate mitral regurgitation, or for patients who are unstable during the procedure.

Animals↗
PubMed2002

A comprehensive strategy to avoid transesophageal echocardiography probe damage.

PURPOSE: To describe the factors predisposing to transesophageal echocardiography (TEE) probe damage and to propose a strategy aimed at preventing damage to the TEE probe. Description of equipment and procedures: Damage to the TEE probe can occur anywhere and anytime during use in the operating room (OR) or when the probe is not in use in the OR, such as in the cleaning room, during storage or during transport of the probe. The components of the strategy used in our institution to avoid probe damage are: 1) storage of the probe in a dedicated holder in the OR when it is not in use, 2) use of a lexan box in the OR to protect the probe connector, 3) use of a custom-made holder when the probe is inserted in the patient, 4) use of a dedicated holder for soiled TEE probe storage in the cleaning room and for subsequent probe storage. CONCLUSION: We describe a comprehensive strategy designed to decrease TEE probe damage and the associated expenses. Further studies will be required to determine the effectiveness of the proposed measures.

Echocardiography, Transesophageal↗