Dirk Meininger

Point-of-care testing: a prospective, randomized clinical trial of efficacy in coagulopathic cardiac surgery patients.

Introduction: The current investigation aimed to study the efficacy of hemostatic therapy guided either by conventional coagulation analyses or point-of-care (POC) testing in coagulopathic cardiac surgery patients. Methods: Patients undergoing complex cardiac surgery were assessed for eligibility. Those patients in whom diffuse bleeding was diagnosed after heparin reversal or increased blood loss during the first 24 postoperative hours were enrolled and randomized to the conventional or POC group. Thromboelastometry and whole blood impedance aggregometry have been performed in the POC group. The primary outcome variable was the number of transfused units of packed erythrocytes during the first 24 h after inclusion. Secondary outcome variables included postoperative blood loss, use and costs of hemostatic therapy, and clinical outcome parameters. Sample size analysis revealed a sample size of at least 100 patients per group. Results: There were 152 patients who were screened for eligibility and 100 patients were enrolled in the study. After randomization of 50 patients to each group, a planned interim analysis revealed a significant difference in erythrocyte transfusion rate in the conventional compared with the POC group [5 (4;9) versus 3 (2;6) units [median (25th and 75th percentile)], P < 0.001]. The study was terminated early. The secondary outcome parameters of fresh frozen plasma and platelet transfusion rates, postoperative mechanical ventilation time, length of intensive care unit stay, composite adverse events rate, costs of hemostatic therapy, and 6-month mortality were lower in the POC group. Conclusions: Hemostatic therapy based on POC testing reduced patient exposure to allogenic blood products and provided significant benefits with respect to clinical outcomes.

Venoarterial extracorporeal membrane oxygenation for treatment of cardiogenic shock: Clinical experiences in 45 adult patients

OBJECTIVE Venoarterial extracorporeal membrane oxygenation is an established treatment option in patients with cardiogenic shock. This report reviews our 3-year experience with this support system with respect to early and midterm outcome, as well as predictors of survival. METHODS From January 2003 until November 2006, 45 (0.8%) of 5750 patients undergoing cardiac surgery procedures required the following: temporary extracorporeal membrane oxygenation support coronary artery bypass grafting, n = 20; implantation of a left ventricular assist device, n = 5; heart transplantation, n = 1; heart and lung transplantation, n = 1; coronary artery bypass grafting plus repair of postinfarction ventricular septal defect, n = 3; coronary artery bypass grafting plus mitral valve repair, n = 5; aortic valve replacement, n = 2; coronary artery bypass grafting plus aortic valve replacement, n = 3; and other procedures, n = 5. Extracorporeal membrane oxygenation implantation was performed through the femoral vessels or axillary artery or through the right atrium and ascending aorta. Additional intra-aortic balloon pumps were used in 30 patients. RESULTS Average patient age was 60.1 +/- 13.6 years. There were 35 male patients. Average duration of extracorporeal membrane oxygenation was 6.4 +/- 4.5 days. Twenty-five patients could be successfully weaned from extracorporeal membrane oxygenation. The 30-day mortality was 53% (24/45 patients). The in-hospital mortality was 71% (32/45 patients). Thirteen (29%) patients could be successfully discharged. After a follow-up period of up to 3 years, 10 (22%) patients were still alive. CONCLUSIONS Extracorporeal membrane oxygenation offers sufficient cardiopulmonary support in adults with similar hospital and midterm survival rates to those of other mechanical support systems. Early indication, alternative peripheral cannulation techniques, and reduced anticoagulation to avoid perioperative bleeding could improve our results with increasing experience.

Positive end‐expiratory pressure improves arterial oxygenation during prolonged pneumoperitoneum

Background:  Laparoscopic surgery usually requires the use of a pneumoperitoneum by insufflating gas in the peritoneal space. The gas most commonly used for insufflation is carbon dioxide. Increased intra‐abdominal pressure causes cephalad displacement of the diaphragm resulting in compressed lung areas, which leads to formation of atelectasis, especially during mechanical ventilation. The aim of this prospective study was to investigate the effect of prolonged intraperitoneal gas insufflation on arterial oxygenation and hemodynamics during mechanical ventilation with and without positive end‐expiratory pressure (PEEP).

Single-dilator percutaneous tracheostomy: a comparison of PercuTwist and Ciaglia Blue Rhino techniques

AbstractObjective. To compare two single-dilator percutaneous tracheostomy techniques, Ciaglia Blue Rhino and the new PercuTwist technique. Design and setting. Randomized, observational clinical trial in patients undergoing elective percutaneous tracheostomy in the intensive care units of a university hospital. Patients. Seventy consecutive, adult patients undergoing either Blue Rhino (n=35) or PercuTwist tracheostomy (n=35). Interventions. Performance of percutaneous tracheostomy with a novel screwlike dilating device (PercuTwist) or conically shaped, flexible rubber dilator (Blue Rhino). Results. Stoma dilation was successful with the respective device in all patients. While subsequent tracheostomy cannula insertion was uneventful in all but one patients undergoing the Blue Rhino technique, it was difficult or even impossible in eight patients who underwent PercuTwist tracheostomy. Regarding serious and intermediate procedural-related complications, two cases of posterior tracheal wall injury occurred with the PercuTwist technique. No serious or intermediate complications were noted during Blue Rhino tracheostomy. There was no statistical significance between the two techniques in terms of minor and overall complications. Conclusions. So far the new PercuTwist technique represents an alternative to the established Blue Rhino technique. Nonetheless, the two cases of posterior tracheal wall injury should not be underestimated, on the one hand, but, on the other, may be attributed to a learning curve with a new technique. The new PercuTwist technique should be performed by various teams and in a considerably larger numbers of patients before an ultimate rating can be made.

Tranexamic acid partially improves platelet function in patients treated with dual antiplatelet therapy.

Background Although the impact of tranexamic acid on platelet function remains controversial, tranexamic acid is part of clinical algorithms for the management of platelet dysfunction. The goal of our prospective, observational study was to examine the effects of tranexamic acid on platelet function in patients treated with dual antiplatelet therapy compared to those who ceased antiplatelet therapy for at least 7 days. Methods Forty patients scheduled for cardiac surgery were enrolled in this study. Group 1 consisted of 20 patients who ceased antiplatelet therapy with aspirin and clopidogrel at least 7 days before surgery. Group 2 consisted of 20 patients who were treated with aspirin and clopidogrel until the day before surgery. Using the Multiplate device (Dynabyte, Munich, Germany), multiple electrode aggregometry (MEA) was performed following platelet stimulation with thrombin receptor activating peptide-6 (TRAP-6), arachidonic acid or ADP on blood collected 20 min before and after application of 2 g tranexamic acid. Results Compared with group 1, platelet aggregation was statistically significantly reduced in ASPItest and ADPtest in group 2, whereas there were no significant differences in the TRAPtest. In group 1, platelet aggregation did not differ significantly before and after tranexamic acid treatment. In contrast, in group 2, we observed a significant increase in arachidonic acid-induced [295 (280/470) arbitrary aggregation units × min [AU*min; median (25th/75th percentile) vs. 214 (83/409) AU*min, P = 0.01] and ADP-induced platelet aggregation [560 AU*min (400/760 AU*min) vs. 470 AU*min (282/550 AU*min), P = 0.013], whereas platelet aggregation following stimulation with TRAP-6 did not change significantly [980 (877/1009) AU*min, median (25th/75th percentile) after tranexamic acid vs. 867 (835/961) AU*min before tranexamic acid, P = 0.464]. Conclusion The results of this study indicate that tranexamic acid potentially corrects defects in arachidonic acid-induced and ADP-induced platelet aggregation imposed by dual antiplatelet therapy. However, platelet aggregation in response to arachidonic acid or ADP in the blood of patients who have not received aspirin and clopidogrel is unaffected by tranexamic acid. These results support the use of tranexamic acid to partially reverse platelet aggregation dysfunction due to antiplatelet therapy.

Brief report: Tracheal intubation using the Bonfils intubation fibrescope or direct laryngoscopy for patients with a simulated difficult airway

Background: The Bonfils intubation fibrescope (BIF), a rigid, straight and reusable fibreoptic device, is being used increasingly to facilitate endotracheal intubation after direct laryngoscopy has failed. We tested the hypothesis that, with the BIF compared to direct laryngoscopy, the rate of failed endotracheal intubation could be reduced in patients with a difficult airway, simulated by means of a rigid cervical immobilization collar.Methods: Seventy-six adults undergoing elective gynecological surgery under general anesthesia were randomly assigned to have endotracheal intubation, facilitated with either a standard size 3 Macintosh laryngoscope blade, or the BIF. A rigid cervical immobilization collar was used to simulate a difficult airway, by reducing mouth opening and limiting neck extension. If endotracheal intubation could not be achieved within two attempts, the cervical collar was removed, and direct laryngoscopy was performed thereafter, using a Macintosh blade in all subjects. The success rate of endotracheal tube placement was the primary outcome variable.Results: Patient characteristics were similar in the two groups. After neck immobilization, the inter-incisor distance was reduced to 2.6±0.7 cm (Macintosh) and 2.6±0.8 cm (BIF). Tube placement was successful in 15/38 (39.5%) patients with a Macintosh blade, and in 31/38 patients with the BIF (81.6%;P=0.0003). Time required for tube placement was 53±22 sec (Macintosh) and 64±24 sec (BIF;P=0.15). Conclusion: The Bonfils intubation fibrescope is a more effective intubating device for patients with immobilized cervical spine and significantly limited inter-incisor distance, when compared to direct laryngoscopy.RésuméContexte: Le fibroscope d’intubation Bonfils (BIF) est un appareil fibroscopique rigide, droit et réutilisable qui est de plus en plus utilisé pour faciliter l’intubation endotrachéale lors de l’échec d’une laryngoscopie directe. Nous avons testé l’hypothèse que lorsque le BIF est comparé à la laryngoscopie directe, le taux d’échec de l’intubation endotrachéale pouvait tre réduit chez des patients présentant des voies aériennes difficiles, lesquelles ont été simulées gr?ce à un collier d’immobilisation cervicale rigide.Méthode: Soixante-seize adultes devant subir une chirurgie gynécologique programmée sous anesthésie générale ont été randomisées à recevoir une intubation endotrachéale, facilitée soit par une lame de laryngoscope Macintosh de taille standard 3 ou par le BIF. Un collier d’immobilisation cervicale rigide a été placé pour simuler des voies aériennes difficiles en réduisant l’ouverture de la bouche et en limitant l’extension du cou. Si l’intubation trachéale ne réussissait pas après deux essais, le collier cervical était retiré et une laryngoscopie directe réalisée ensuite à l’aide d’une lame Macintosh chez toutes les patientes. Le critère d’efficacité principal était le taux de positionnement correct de la sonde endotrachéale.Résultats: Les caractéristiques des patientes étaient similaires dans les deux groupes. Après immobilisation du cou, l’espace entre les incisives a été réduit à 2,6±0,7 cm (Macintosh) et 2,6±0,8 cm (BIF). La sonde a été placée correctement chez 15/38 (39,5%) patientes avec une lame Macintosh et chez 31/38 patientes avec le BIF (81,6%; P=0,0003). Le temps requis pour le positionnement de la sonde était de 53±22 sec (Macintosh) et 64±24 sec (BIF; P=0,15).Conclusion: Comparé à la laryngoscopie directe, le fibroscope d’intubation Bonfils est un appareil d’intubation plus efficace pour les patients ayant la colonne cervicale immobilisée et un espace entre les incisives considérablement limité.

Totally endoscopic Nissen fundoplication with a robotic system in a child.

A 67-year-old woman presented with severe cardiopulmonary insufficiency 17 days after an uneventful laparoscopic cholecystectomy. Pulmonary thromboembolism was demonstrated by transthoracic echocardiogram and later confirmed at surgery. With the aid of a cardiopulmonary bypass, a thrombectomy of the right atrium and the pulmonary artery was accomplished. The patient could not be weaned off cardiopulmonary bypass and ultimately died. We therefore recommend antithromboembolism therapy with low-molecular-weight heparin in selected cases of laparoscopic cholecystectomy.

Effects of prolonged pneumoperitoneum on hemodynamics and acid-base balance during totally endoscopic robot-assisted radical prostatectomies.

Laparoscopic techniques have become a standard approach for diagnostic and therapeutic procedures in many surgical disciplines. Recent progress in endoscopic surgery is based on the integration of computer-enhanced telemanipulation systems. Because robot-assisted radical prostatectomies take up to 10 hours, the present study was performed to evaluate the effects of prolonged intraperitoneal CO2 insufflation on hemodynamics and gas exchange in 15 patients with prostate cancer. When CO2 insufflation was initiated, peak inspiratory pressure increased and reached significant values after a 1.5-hour period of intraperitoneal CO2 insufflation. With the release of CO2, peak inspiratory pressure decreased close to baseline values. A significant increase in heart rate was observed after a 4-hour period of increased intraabdominal pressure. Mean arterial blood pressure and central venous pressure remained stable during CO2 insufflation. Minute ventilation was adjusted according to repeated blood gas analyses to maintain pH, base excess (BE), bicarbonate (HCO3−), and PaCO2 within physiologic ranges. The present data show, that prolonged CO2 insufflation during totally endoscopic robot-assisted radical prostatectomy results in only minor changes in hemodynamics and acid-base status. Because of the limited experience with long-term pneumoperitoneum, we consider invasive haemodynamic monitoring and repeat blood gas analysis essential for such operations.RésuméLa technique laparoscopique est devenue le standard pour beaucoup de procédés diagnostiques et thérapeutiques dans diverses disciplines chirurgicales. De progrès récents en chirurgie endoscopique sont basés sur l’intégration de systèmes de la télémanipulation sur ordinateur. Puisque à présent, les prostatectomies radicales assistées par robot peuvent durer jusqu’à 10 heures, cette étude a été entreprise pour évaluer les effets de l’insufflation intrapéritonéale prolongée par le CO2 sur l’hémodynamique et les échanges gazeux chez 15 patients porteurs de cancer de la prostate. Au début de l’insufflation par le CO2, la pression inspiratoire maximale a augmenté et a atteint des valeurs significatives après 1.5 heures d’insufflation intrapéritonéale. Lorsque l’on a arrêté l’insufflation par le CO2, la pression inspiratorie maximale a diminué pour se rapprocher des valeurs de base. On a observé une augmentation significative de la fréquence cardiaque après 4 heures d’hyperpression intra-abdominale. La pression artérielle moyenne et la pression veineuse centrale sont restées stables pendant l’insufflation par le CO2. La ventilation minute a été ajustée selon les analyses des gaz du sang répétées pour maintenir le pH, la base-excès, les taux de HCO3− et de PaCO2 dans les limites de la normale. Nos données actuelles nous montrent que l’insufflation prolongée de CO2 pendant la prostatectomie radicale endoscopique assistée par robot ne modifie que peu l’état hémodynamique et l’équilibre acido-basique. En raison d’une expérience limitée en ce qui concerne le pneumopéritoine prolongé, nous considérons que le monitorage hémodynamique invasif et l’analyse répétée des gaz du sang sont essentiels pour de telles opérations.ResumenEn muchas especialidades quirúrgicas las técnicas laparoscópicas se han convertidomen en procedimientos estándar tanto con fines diagnósticos como terapéuticos. Progresos recientes han permitido integrar la cirugía endoscópica en sistemas computarizados propiciando las técnicas de telecirugía y telemanipulación. Dado que la prostatectomía radical con ayuda de un robot dura más de 10 horas, estudiamos los efectos de un neumoperitoneo prolongado con CO2 en la hemodinamia e intercambio gaseoso en 15 pacientes con cáncer de próstata. Al iniciar la insuflación de CO2 la presión inspiratoria aumenta y alcanza valores significativos a las 1–5 horas de la instauración del neumoperitoneo. Cuando éste desaparece la presión inspiratoria máxima desciende a nivel basai. La presión arterial media (MAP) y la venosa central (PVC) se mantienen estables durante el neumoperitoneo. La ventilación minuto ha de ajustarse de acuerdo con gasometrías repetidas para mantener dentro de límites normales el pH, BE, HCQ3− y la PaCO2. Nuestros hallazgos demuestran que el neumoperitoneo prolongado por prostatectomía radical asistida mediante un robot produce cambios mínimos hemodinámicos y del equilibro ácido-base. Dada la corta experiencia con neumoperitoneo de larga duración, en estas operaciones son obligatorios la monitorización invasiva hemodinámica y frecuentes análisis gasométricos.

Impact of Overweight and Pneumoperitoneum on Hemodynamics and Oxygenation during Prolonged Laparoscopic Surgery

BackgroundAnesthesia adversely affects respiratory function and hemodynamics in obese patients. Although many studies have been performed in morbidly obese patients, data are limited concerning overweight patients [BMI 25–29.9 kg m−2]. The aim of this study was to evaluate the effects of prolonged pneumoperitoneum in Trendelenburg position on hemodynamics and gas exchange in normal and overweight patients.MethodsWe studied 15 overweight and 15 non-obese [BMI 18.5–24.9 kg m−2] patients who underwent totally endoscopic robot-assisted radical prostatectomy under general anesthesia with an inspired oxygen fraction of 0.5. A standardized anesthetic regimen was used, and patients were examined at standard times: after induction of anesthesia and Trendelenburg posture, every 30 minutes after establishing pneumoperitoneum, and after the release of the pneumoperitoneum with the patient still in Trendelenburg position.ResultsAfter induction of anesthesia and Trendelenburg positioning arterial oxygen pressure [PaO2] and alveolar-arterial difference in oxygen tension [AaDO2] differed significantly between both groups with lower PaO2 [235 ± 27 versus 164 ± 51 mmHg] and higher AaDO2 [149 ± 48 versus 76 ± 28 mmHg] values in overweight patients. During pneumoperitoneum, PaO2 transient increased above baseline values in overweight patients, whereas AaDO2 decreased. Hemodynamic parameters [HR, MAP, and CVP] did not differ significantly between groups.ConclusionsArterial oxygenation and AaDO2 are significantly impaired in overweight patients under general anesthesia in Trendelenburg posture. In overweight patients pneumoperitoneum transient reduced the impairment of arterial oxygenation and lead to a decrease in AaDO2. Hemodynamic parameters were not affected by body weight.

Hemodynamics and gas exchange during carbon dioxide insufflation for totally endoscopic coronary artery bypass grafting

BACKGROUND In addition to single-lung ventilation (SLV), positive-pressure CO2 insufflation is mandatory for totally endoscopic coronary artery bypass grafting. Studies on the effects of unilateral CO2 insufflation on hemodynamics produced controversial results, and bilateral insufflation has not been studied to our knowledge. The present study sought to investigate hemodynamics and gas exchange during unilateral and bilateral CO2 insufflation in patients who underwent totally endoscopic coronary artery bypass grafting. METHODS Eleven hemodynamic and gas exchange variables were monitored during 22 totally endoscopic coronary artery bypass grafting procedures with unilateral (n = 17) or bilateral (n = 5) CO2 insufflation at a pressure of 10 to 12 mm Hg. Data were obtained at baseline with double-lung ventilation, after institution of SLV, during insufflation, after cardiopulmonary bypass during SLV, and after return to double-lung ventilation. RESULTS Arterial oxygen tension decreased significantly during SLV, whereas the peak inspiratory pressure increased. In addition, central venous pressure and heart rate increased significantly during insufflation, but mean arterial pressure remained unchanged. Although the end-tidal CO2 pressure did not change, arterial carbon dioxide tension increased progressively to a maximum of 44.6 +/- 5.9 mm Hg during unilateral insufflation, and 55.7 +/- 14.6 mm Hg during bilateral insufflation (p < 0.05 versus baseline and between groups). Mixed venous oxygen saturation declined during SLV regardless of CO2 insufflation and recovered to baseline once double-lung ventilation was restarted. Left and right ventricular ejection fractions remained unaltered. No patient required inotropic or vasopressor support. CONCLUSIONS Carbon dioxide insufflation for totally endoscopic coronary artery bypass grafting with SLV had no adverse effects on hemodynamics. In contrast to a moderate increase of arterial carbon dioxide tension during unilateral insufflation, markedly elevated arterial carbon dioxide tension levels remain a cause of concern during bilateral insufflation.