Emergent transesophageal echocardiography in hemodynamically unstable obstetric patients.

BACKGROUND: The obstetric population has an increasing incidence of comorbid conditions. These, coupled with the possibility of acute embolic events involving air, amniotic fluid, and thrombus, increase the likelihood of hemodynamic instability. Although the utility of transesophageal echocardiography to guide management in cardiac and high-risk, non-cardiac surgical populations has been well established, the emergent use in critically-ill parturients has not been comprehensively evaluated. METHODS: Using our departmental transesophageal echocardiography database of 28 293 examinations, parturients were identified who underwent emergent transesophageal echocardiography for evaluation of hemodynamic instability, including cardiac arrest, between January 1999 and March 2014. Transesophageal echocardiography findings and their impact on patient management were analyzed. RESULTS: Ten peripartum patients were evaluated. Six patients became unstable during dilation and evacuation procedures; one after a forceps delivery; one during and one after cesarean delivery; and one during a postpartum laparotomy. Six patients proceeded to cardiac arrest; however, all women survived their initial operation and resuscitation. Transesophageal echocardiography was instrumental in determining the etiology and guiding resuscitation in all 10 patients including emergent cardiac surgical intervention with cardiopulmonary bypass (n=2). Seven patients survived to hospital discharge, but three died after experiencing neurologic complications. CONCLUSIONS: Severe hemodynamic instability and cardiac arrest can occur in previously healthy parturients in pregnancy. Our data suggest that emergent transesophageal echocardiography is a valuable tool in determining the etiology and directing therapy of refractory hypotension or cardiac arrest in obstetric patients.

Remifentanil or sufentanil for coronary surgery: comparison of postoperative respiratory impairment.

BACKGROUND AND OBJECTIVE: High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome. METHODS: Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5-1.0 microg kg(-1) min(-1)) or propofol/sufentanil (30-40 ng kg(-1) min(-1)) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group. RESULTS: Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05). CONCLUSIONS: Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

[Perioperative echocardiography: basic principles]. / Perioperative Echokardiographie: Technische Grundlagen für den Kliniker.

Over the past decades, echocardiography has undergone a continuous evolution in technology that has promoted its clinical application and acceptance throughout perioperative medicine. These technological advances include improvements in transducer development that permit superior imaging quality and a wider selection of probes for epicardial, epiaortic, and surface echocardiography which can also be used in conjunction with multiplane transesophageal echocardiography. Moreover, the addition of Doppler technology and digital acquisition has secured the role of echocardiography as a valuable and relatively noninvasive diagnostic tool for the assessment of cardiovascular disease and hemodynamic monitoring throughout the perioperative period. Therefore, it has become increasingly important for perioperative physicians to understand the basic principles and underlying fundamental concepts pertaining to the technology and physics of echocardiography, as well as its inherent limitations. The current review outlines the modes and applications of different echocardiographic techniques used in perioperative echocardiography including M-mode, two-dimensional echocardiography, and Doppler assessment of blood flow. In addition, the limitations of these techniques and typical artifacts associated with the perioperative use of echocardiography are described.

Inhibition of complement activation by pexelizumab reduces death in patients undergoing combined aortic valve replacement and coronary artery bypass surgery.

OBJECTIVE: We sought to evaluate the effects of pexelizumab, a C5 complement inhibitor, on death and myocardial infarction in patients undergoing combined aortic valve replacement and coronary artery bypass grafting surgery. METHODS: The Pexelizumab for Reduction in Myocardial Infarction and Mortality in Coronary Artery Bypass Graft surgery trial, a phase III prospective, randomized, double-blind, placebo-controlled study, enrolled 3099 patients at 205 centers. The primary end point was the composite of death, myocardial infarction, or both at postoperative day 30 in patients undergoing coronary artery bypass grafting without valve surgery. Postoperative myocardial infarction was defined as a creatine kinase MB fraction value of 100 ng/mL or greater, Q-wave myocardial infarction with a creatine kinase MB fraction value of 70 ng/mL or greater, or new Q-wave evidence of myocardial infarction by postoperative day 30. Because patients undergoing coronary artery bypass grafting with a valve procedure were not included in the primary population, separate analysis of death and myocardial infarction was conducted in 218 patients undergoing combined aortic valve replacement and coronary artery bypass grafting surgery. RESULTS: Of the 353 patients randomized to any valve procedure, 106 (61%) underwent combined aortic valve replacement and coronary artery bypass grafting in the pexelizumab treatment group compared with 112 (63%) patients in the placebo group. Coronary artery bypass grafting was performed with 1 or more internal thoracic artery grafts in 139 (64%) patients and with 1 or more saphenous vein grafts in 179 (82%) patients. There were 4 (3.8%) deaths in the pexelizumab group versus 11 (9.9%) in the placebo group by postoperative day 30 and 6 (5.7%) deaths in the active group versus 16 (14.4%) in the placebo group by postoperative day 180 (P =.107 and P =.043, respectively, Fisher exact test). The incidence of myocardial infarction 30 days after surgical intervention was identical in the 2 groups, but the study was not designed to detect differences in this cohort of patients. CONCLUSIONS: Inhibition of complement activation by pexelizumab resulted in a decreased mortality at 180 days among 218 patients who underwent combined aortic valve replacement and coronary artery bypass grafting surgery. Additional studies are warranted to confirm this decrease in mortality with pexelizumab in combined aortic valve replacement and coronary artery bypass grafting procedures.

[Epicardial echocardiography intraoperative diagnostic utility to assess valve function]. / Epikardiale EchokardiographieIntraoperative Beurteilung der Klappenfunktion.

Epicardial echocardiography has been available since the early 1970s as an intraoperative diagnostic modality to assess ventricular and valvular function. With this technique, an ultrasonic transducer is placed directly on the epicardial surface of the heart, following sternotomy and pericardiotomy. Under the guidance of the cardiac anesthesiologist, the surgeon places the transducer so that the desired views of cardiac structures and great vessels can be obtained. The anesthesiologist performs the acquisition, analysis and interpretation of the echocardiographic images. Despite the feasibility of epicardial echocardiography, transesophageal echocardiography (TEE) has emerged over the last two decades as the main form of intraoperative echocardiography. Although TEE allows continuous monitoring of cardiac and valvular function without interruption of the surgical procedure, placement of a TEE probe may be difficult or contraindicated in some patients. In such cases, epicardial echocardiography may be the optimal ultrasonographic imaging modality to assess ventricular and valvular function during cardiac surgery. We describe the use of epicardial echocardiography for intraoperative assessment of valvular function in two patients where TEE was either contraindicated or probe placement could not be performed safely. The first patient underwent surgical repair of the mitral valve for severe mitral regurgitation. After weaning the patient from cardiopulmonary bypass (CPB), epicardial echocardiography was used to confirm successful reconstruction of the valve and to exclude residual mitral regurgitation. The second patient was scheduled for coronary artery bypass grafting (CABG). Prior to the initiation of CPB, the presence of moderate aortic stenosis was confirmed using Doppler echocardiography via an epicardial approach.

Role of the complement system in ischaemic heart disease: potential for pharmacological intervention.

The complement system is an innate, cytotoxic host defence system that normally functions to eliminate foreign pathogens. However, considerable evidence suggests that complement plays a key role in the pathophysiology of ischaemic heart disease (IHD). Experimental models of acute myocardial infarction (MI) and autopsy specimens taken from acute MI patients demonstrate that complement is selectively deposited in areas of infarction. Furthermore, inhibition of complement activation or depletion of complement components prior to myocardial reperfusion has been shown to reduce complement-mediated tissue injury in numerous animal models. IHD remains a leading cause of patient morbidity and mortality. Considerable effort in recent years has therefore been directed by biotechnology and pharmaceutical industries towards the development of novel, human complement inhibitors. Proposed anticomplement therapeutic strategies include the administration of naturally occurring or recombinant complement regulators, anticomplement monoclonal antibodies, and anticomplement receptor antagonists. Although data regarding the effectiveness of anticomplement therapy in humans is limited at present, a number of novel anticomplement therapeutic strategies are currently in clinical trials. The role of complement in IHD and potential for pharmacological intervention is reviewed.

The safety of intraoperative transesophageal echocardiography: a case series of 7200 cardiac surgical patients.

UNLABELLED: Transesophageal echocardiography (TEE) is an invaluable intraoperative diagnostic monitor that is considered to be relatively safe and noninvasive. Insertion and manipulation of the TEE probe, however, may cause oropharyngeal, esophageal, or gastric trauma. We report the incidence of intraoperative TEE-associated complications in a single-center series of 7200 adult cardiac surgical patients. Information related to intraoperative TEE-associated complications was obtained retrospectively from the intraoperative TEE data form, routine postoperative visits, and cardiac surgical morbidity and mortality data. The overall incidences of TEE-associated morbidity and mortality in the study population were 0.2% and 0%, respectively. The most common TEE-associated complication was severe odynophagia, which occurred in 0.1% of the study population. Other complications included dental injury (0.03%), endotracheal tube malpositioning (0.03%), upper gastrointestinal hemorrhage (0.03%), and esophageal perforation (0.01%). TEE probe insertion was unsuccessful or contraindicated in 0.18% and 0.5% of the study population, respectively. These data suggest that intraoperative TEE is a relatively safe diagnostic monitor for the management of cardiac surgical patients. IMPLICATIONS: The overall morbidity (0.2%) and mortality (0%) rates of intraoperative transesophageal echocardiography (TEE) were determined in a retrospective case series of 7200 adult, anesthetized cardiac surgical patients. The most common source of TEE-associated morbidity was odynophagia (0.1%), which resolved with conservative management. These results suggest that TEE is a safe diagnostic tool for the management of cardiac surgical patients.

Effect of nitric oxide upon gas transfer and structural integrity of a polypropylene membrane oxygenator.

Gaseous nitric oxide (NO) may act as a membrane passivator during cardiopulmonary bypass by inhibition of platelet and leukocyte adhesion, activation, and aggregation. However, NO and its by-product nitrogen dioxide (NO2) are potently reactive and may be capable of degradation of membrane oxygenator constituents in an oxygen-rich environment. To test these concepts, nine polypropylene hollow fiber membrane oxygenators received 224 +/- 10 ppm NO and 6.7 +/- 1.7 ppm NO2 in 73% oxygen (O2), and six oxygenators received 73% O2, while being perfused with heparinized thrombocytopenic bovine blood for 6 hours. Oxygenators were used for measurement of O2 and carbon dioxide (CO2) transfer rates, structural integrity by pulsing with 22 psi water at 0.5 Hz for 6 hours, and scanning electron microscopic (SEM) examination of structural integrity. Transfer rates between groups at 0, 1, 3, and 6 hours revealed no differences in O2 or CO2. No oxygenator failed hydraulic tests of structural integrity or exhibited "wet-out" during bypass. No evidence of material degradation was shown in the SEM appearance of oxygenators. There were no differences in hematologic values. These data support the safety of gaseous NO in polypropylene membrane oxygenators for limited-term cardiopulmonary bypass.

Pharmacology and biological efficacy of a recombinant, humanized, single-chain antibody C5 complement inhibitor in patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass (CPB) induces a systemic inflammatory response that causes substantial clinical morbidity. Activation of complement during CPB contributes significantly to this inflammatory process. We examined the capability of a novel therapeutic complement inhibitor to prevent pathological complement activation and tissue injury in patients undergoing CPB. METHODS AND RESULTS: A humanized, recombinant, single-chain antibody specific for human C5, h5G1.1-scFv, was intravenously administered in 1 of 4 doses ranging from 0.2 to 2.0 mg/kg before CPB. h5G1.1-scFv was found to be safe and well tolerated. Pharmacokinetic analysis revealed a sustained half-life from 7.0 to 14.5 hours. Pharmacodynamic analysis demonstrated significant dose-dependent inhibition of complement hemolytic activity for up to 14 hours at 2 mg/kg. The generation of proinflammatory complement byproducts (sC5b-9) was effectively inhibited in a dose-dependent fashion. Leukocyte activation, as measured by surface expression of CD11b, was reduced (P<0.05) in patients who received 1 and 2 mg/kg. There was a 40% reduction in myocardial injury (creatine kinase-MB release, P=0.05) in patients who received 2 mg/kg. Sequential Mini-Mental State Examinations (MMSE) demonstrated an 80% reduction in new cognitive deficits (P<0.05) in patients treated with 2 mg/kg. Finally, there was a 1-U reduction in postoperative blood loss (P<0. 05) in patients who received 1 or 2 mg/kg. CONCLUSIONS: A single-chain antibody specific for human C5 is a safe and effective inhibitor of pathological complement activation in patients undergoing CPB. In addition to significantly reducing sC5b-9 formation and leukocyte CD11b expression, C5 inhibition significantly attenuates postoperative myocardial injury, cognitive deficits, and blood loss. These data suggest that C5 inhibition may represent a novel therapeutic strategy for preventing complement-mediated inflammation and tissue injury.

Safety and efficacy of shed mediastinal blood transfusion after cardiac surgery: a multicenter observational study. Multicenter Study of Perioperative Ischemia Research Group.

OBJECTIVE: To examine the efficacy and safety of shed mediastinal blood (SMB) transfusion in preventing allogenic red blood cell (RBC) transfusion. DESIGN: An observational clinical study. SETTING: Twelve US academic medical centers. PARTICIPANTS: Six hundred seventeen patients undergoing elective primary coronary artery bypass grafting. INTERVENTIONS: Patients were administered SMB transfusion or not, according to institutional and individual practice, without random assignment. MEASUREMENTS AND RESULTS: The independent effect of SMB transfusion on postoperative RBC transfusion was examined by multivariable modeling. Potential complications of SMB transfusion, such as bleeding and infection, were examined. Three hundred twelve of the study patients (51%) received postoperative SMB transfusion (mean volume, 554 +/- 359 mL). Patients transfused with SMB had significantly lower volumes of RBC transfusion than those not receiving SMB (0.86 +/- 1.50 v 1.08 +/- 1.65 units; p < 0.05). However, multivariable analysis showed that SMB transfusion was not predictive of postoperative RBC transfusion. Demographic factors (older age, female sex), institution, and postoperative events (greater chest tube drainage, lower hemoglobin level on arrival to the intensive care unit, and use of inotropes) were significant predictors of RBC transfusion. The volume of chest tube drainage on the operative day (707 +/- 392 v 673 +/- 460 mL; p = 0.30), reoperation for hemorrhage (3.1% v2.5%; p = 0.68), and overall frequency of infection (5.8% v 6.6%; p = 0.81) were similar between patients receiving and not receiving SMB, respectively. However, in patients who did not receive allogenic RBC transfusion, there was a significantly greater frequency of wound infection in the SMB group (3.6% v0%; p = 0.02). CONCLUSION: These data suggest that SMB is ineffective as a blood conservation method and may be associated with a greater frequency of wound infection.

Percutaneous coronary sinus cannulation guided by transesophageal echocardiography.

We investigated whether percutaneous cannulation of the coronary sinus could be accomplished without fluoroscopy using transesophageal echocardiography in patients undergoing minimally invasive cardiac operations. The coronary sinus was cannulated without significant complications using transesophageal echocardiography in 10 of 11 patients (mean, 10.5 minutes). Percutaneous cannulation of the coronary sinus can be accomplished in a safe and efficient manner using transesophageal echocardiography without the need for fluoroscopy.

Influence of inhaled nitric oxide on systemic flow and ventricular filling pressure in patients receiving mechanical circulatory assistance.

BACKGROUND: In patients with left ventricular (LV) dysfunction, inhaled nitric oxide (NO) decreases pulmonary vascular resistance (PVR) but causes a potentially clinically significant increase in left atrial pressure (LAP). This has led to the suggestion that inhaled NO may reach the coronary circulation and have a negative inotropic effect. This study tested an alternative hypothesis that LAP increases because of volume shifts to the pulmonary venous compartment caused by NO-induced selective pulmonary vasodilation. METHODS AND RESULTS: The Thermo Cardiosystems Heartmate is an LV assist device (LVAD) that can be set (by controlling pump rate) to deliver fixed or variable systemic blood flow. Eight patients (between 1 and 11 days after LVAD implantation) were administered inhaled NO (20 and 40 ppm for 10 minutes), and LAP, systemic flow, and pulmonary arterial pressure were measured in both fixed and variable pump flow modes. In both modes, inhaled NO lowered PVR (by 25 +/- 6% in the fixed mode, P < .001, and by 21 +/- 5% in the variable mode, P < .003). With fixed pump flow, LAP rose from 12.5 +/- 1.2 to 15.1 +/- 1.4 mm Hg (P < .008). In the variable flow mode, LAP did not increase and the assist device output rose from 5.3 +/- 0.3 to 5.7 +/- 0.3 L/min (P < .008). CONCLUSIONS: A selective reduction in PVR by inhaled NO can increase LAP if systemic flow cannot increase. These data support the hypothesis that with LV failure, inhaled NO increases LAP by increasing pulmonary venous volume and demonstrate that inhaled NO has beneficial hemodynamic effects in LVAD patients.

Transmyocardial laser revascularization: operative techniques and clinical results at two years.

OBJECTIVES: A new technique, transmyocardial laser revascularization, provides direct perfusion of ischemic myocardium via laser-created transmural channels. From 1993 to 1995, we have treated 20 patients (mean age 61 years, four women and 16 men) with transmyocardial laser revascularization. Preoperatively, the average angina class was 3.7. The patients were screened before the operation by a technetium sestamibi perfusion scan to identify the location and extent of their reversible ischemia. METHODS: Operative exposure is gained via a left anterior thoracotomy. With the use of a 850-watt carbon dioxide laser, an average of 21 +/- 4 channels were created in 22 minutes with a total operative time of less than 2 hours. RESULTS: The in-hospital mortality was two of 20 patients. Three additional patients died after discharge. After an accumulated 172 patient-months (mean follow-up 11 +/- 8 months, range 1 to 26 months), the mean angina class is I (p = 0.01). Postoperative sestamibi scans were obtained at 3, 6, and 12 months. Using the septum as a control and comparing the postoperative results with the preoperative baseline, we noted a significant improvement in perfusion particularly in the areas of reversible ischemia. CONCLUSION: These early results indicate that transmyocardial laser revascularization is a simple operative technique that may improve myocardial perfusion and provide angina relief for patients in whom standard methods of revascularization is contraindicated.

Nitric oxide: delivery, measurement, and clinical application.

The biologic and therapeutic roles of NO are rapidly being elucidated. Before inhalational NO administration is commonplace, there is a clear need for consensus regarding safe and accurate delivery and measurement systems. The potential for NO usage appears large and potentially life-saving; yet multicenter trials need to carefully evaluate efficacy and safety.