[Strategies for quality assessment of emergency helicopter rescue systems. The Graz model]. / Strategien zur Optimierung notärztlicher Kompetenz in der Flugrettung. Das Modell Graz.

PURPOSE: Preclinical emergency medical treatment necessitates a comprehensive interdisciplinary knowledge by the emergency physician as well as a high level of manual dexterity. The quality of treatment therefore depends on the level of education and continuous training in emergency medical techniques. Based on an evaluation of the frequency of life-saving interventions by a physician-staffed rescue helicopter system, strategies for in-hospital training of relevant skills are suggested. MATERIAL AND METHODS: At the outset, 10 important areas of treatment (e.g. intubation, chest tube etc.) and their frequency in emergency medical services were defined as the standard to be attained by emergency physicians within 1 year. The selection of the areas of treatment was based to some extent on international recommendations. The actual frequencies of the prehospital interventions were compared to the required minimum numbers by retrospective analysis of the helicopter rescue database (NACA-X). RESULTS: During the observation period of 1 year, 20 emergency physicians responded to 956 prehospital emergency calls. A life-threatening condition requiring an on-site intervention occurred in only 521 (54.5%) patients, so that the majority of physicians did not perform the required minimum number of interventions. In order to maintain their level of skill, the emergency physicians were required to undertake additional training at the local university hospital. CONCLUSION: The frequency of on-site life-saving interventions in emergency medicine is insufficient to fulfill the quota necessary to maintain adequate training of emergency physicians. Only a link-up program at a hospital for primary care can ensure an adequate training level.

[Autocapture(TM) and Capture Management(TM) Current concepts in pacing threshold and output management]. / Autocapture(TM)- und Capture-Management(TM) Aktuelle Konzepte zur automatischen Reizschwellenmessung und Anpassung der Stimulationsamplitude.

Pacing threshold is not a stable value during the pacemaker's life. It is affected by many physiological, pharmacological and pathophysiological factors. A pacing system able to confirm capture and automatically adjust its output to the actual pacing threshold is highly desirable for a prolonged battery life and maximal patient safety. The Autocapture(TM) of St. Jude Medical and the Capture Management(TM) of Medtronic are currently available on the market. The key feature is the measurement of the evoked response (ER) signal by the pacemaker for capture confirmation. In case of loss of capture, the Autocapture(TM) System delivers a back up safety pulse of 4.5 Volt and 0.49 ms and starts a new threshold search. The pacemaker adapts its output to 0.3V/0.25V above the newly measured threshold. This system needs bipolar leads with low polarization for the first generation in Microny® and Regency® pacemakers; in the second generation with Affinity® and Integrity® pacemakers various bipolar leads are suitable. The Capture Management(TM) System of Medtronic, available in the Kappa® DR 700 series, performs a two point automatic threshold search once every day during rest. The output is determined by the programmed safety margin (nominal 1.5×voltage threshold). A backup pulse is only delivered during the threshold search. No special electrodes are necessary. These functions were shown to work safely and efficaciously in multicenter trials to decrease the current consumption with a prolongation of battery life up to 142%. The patients safety was increased by identifying changes of the capture threshold over time and adjusting the pacing stimulus. The conventional safety margins of 100% might not be safe for all patients. We also learned much about lead maturation and lead instability by the possibility of continuous follow-up of threshold changes in a larger group of leads in order to identify the risk group of about 10% of patients with late threshold increase and lead instability.

[Lead stability in long-term follow-up of bipolar leads]. / Sondenstabilität im Langzeitverlauf bipolarer Sonden.

From 1990 to 1999, 2,853 ventricular and 1,084 atrial bipolar leads of various manufacturers (Medtronic, Biotronik, Vitatron, Ela, Pacesetter and Stöckert) were implanted during first implantations of pacemakers at the University of Graz, Dept. of Cardiac Surgery. Surgical complications with the need of reintervention were analyzed during a follow up period of up to 10 years. The overall lead-related complication rate for ventricular bipolar leads was 6.5% (187 of 2,853) and 5.3% (58 of 1,084) for atrial bipolar leads. Early complications within the first month were higher in the atrium (5.3% versus 2.2% in the ventricle), primarily due to dislocation, late complications were higher in the ventricle (4.3% versus 2% in the atrium) due to insulation problems and lead fracture. Insulation material had a marked influence with a higher failure rate in some leads with polyurethane insulation compared with silicone. Therefore we recommend a close follow-up of bipolar polyurethane leads by measurement of chronic impedance in order to assess insulation problems as early as possible.

The effect of positive end-expiratory pressure during partial liquid ventilation in acute lung injury in piglets.

OBJECTIVES: To investigate the effects of positive end-expiratory pressure (PEEP) application during partial liquid ventilation (PLV) on gas exchange, lung mechanics, and hemodynamics in acute lung injury. DESIGN: Prospective, randomized, experimental study. SETTING: University research laboratory. SUBJECTS: Six piglets weighing 7 to 12 kg. INTERVENTIONS: After induction of anesthesia, tracheostomy, and controlled mechanical ventilation, animals were instrumented with two central venous catheters, a pulmonary artery catheter and two arterial catheters, and an ultrasonic flow probe around the pulmonary artery. Acute lung injury was induced by the infusion of oleic acid (0.08 mL/kg) and repeated lung lavage procedures with 0.9% sodium chloride (20 mL/kg). The protocol consisted of four different PEEP levels (0, 5, 10, and 15 cm H2O) randomly applied during PLV. The oxygenated and warmed perfluorocarbon liquid (30 mL/kg) was instilled into the trachea over 5 mins without changing the ventilator settings. MEASUREMENTS AND MAIN RESULTS: Airway pressures, tidal volumes, dynamic and static pulmonary compliance, mean and expiratory airway resistances, and arterial blood gases were measured. In addition, dynamic pressure/volume loops were recorded. Hemodynamic monitoring included right atrial, mean pulmonary artery, pulmonary capillary wedge, and mean systemic arterial pressures and continuous flow recording at the pulmonary artery. The infusion of oleic acid combined with two to five lung lavage procedures induced a significant reduction in PaO2/FI(O2) from 485 +/- 28 torr (64 +/- 3.6 kPa) to 68 +/- 3.2 torr (9.0 +/- 0.4 kPa) (p < .01) and in static pulmonary compliance from 1.3 +/- 0.06 to 0.67 +/- 0.04 mL/cm H2O/kg (p < .01). During PLV, PaO2/FI(O2) increased significantly from 68 +/- 3.2 torr (8.9 +/- 0.4 kPa) to >200 torr (>26 kPa) (p < .01). The highest PaO2 values were observed during PLV with PEEP of 15 cm H2O. Deadspace ventilation was lower during PLV when PEEP levels of 10 to 15 cm H2O were applied. There were no differences in hemodynamic data during PLV with PEEP levels up to 10 cm H2O. However, PEEP levels of 15 cm H2O resulted in a significant decrease in cardiac output. Dynamic pressure/volume loops showed early inspiratory pressure spikes during PLV with PEEP levels of 0 and 5 cm H2O. CONCLUSIONS: Partial liquid ventilation is a useful technique to improve oxygenation in severe acute lung injury. The application of PEEP during PLV further improves oxygenation and lung mechanics. PEEP levels of 10 cm H2O seem to be optimal to improve oxygenation and lung mechanics.

Partial liquid ventilation combined with kinetic therapy in acute respiratory failure in piglets.

OBJECTIVE: To investigate the effect of the combination of kinetic therapy (KT) with partial liquid ventilation (PLV) on gas exchange, lung mechanics and hemodynamics in acute lung injury (ALI). DESIGN: Prospective, randomized, controlled pilot study. SETTING: University research laboratory. SUBJECTS: Eleven piglets weighing 8.3+/-0.9 kg. INTERVENTION: ALI was induced by the infusion of oleic acid (0.08 ml/kg) and repeated lung lavages with 0.9% NaCl (20 ml kg(-1)). Thereafter the animals were randomly assigned either for PLV or a combination of PLV with KT (PLV/KT). The dose of perfluorocarbon administered was 30 ml/kg, evaporative losses were substituted with 5 ml/kg per h. MEASUREMENTS AND MAIN RESULTS: Airway pressures, tidal volumes, dynamic compliance (Cdyn), expiratory airway resistance and arterial blood gases were measured. Hemodynamic monitoring included right atrial, mean pulmonary artery, pulmonary capillary wedge and mean systemic arterial pressures, and continuous flow recording of the pulmonary artery. In both groups the induction of ALI significantly reduced PaO2/FIO2 Cdyn and cardiac output, and significantly increased pulmonary artery pressure. After the initiation of PLV there was a significant increase of PaO2/FIO2, and Cdyn, and a significant decrease of pulmonary artery pressure in both groups. Except the PaCO2, which showed significantly lower values in the PLV/KT group, no variables showed any differences between the two groups. CONCLUSION: The additional use of KT did not show beneficial effects on oxygenation and lung mechanics during PLV. However, at constant minute ventilation PaCO2 levels were significantly lower during PLV/KT, indicating some positive influence on the ventilation/perfusion distribution within the lung. Extreme body positions during PLV/KT did not show any significant hemodynamic side effects.

The influence of different strategies on clinical outcome in patients undergoing total cavopulmonary connection.

BACKGROUND: We report on results of a prospective clinical trial designed to demonstrate the influence of various strategies in "Total Cavopulmonary Connection" (TCPC) for palliative therapy of patients with "single ventricle" physiology. METHODS: From 1989 to 1997, a total of 47 patients (mean age 4.8 +/- 3.6 years) underwent definitive TCPC at our unit. 31 patients (66%) underwent one-stage TCPC, in 16 patients (34%) we performed a two-stage modified Fontan operation; 21 patients had central fenestration (4 mm). Inhalative NO therapy in the immediate postoperative period was adopted in 1993. RESULTS: Overall 5-year survival was 76.4%, after two-stage TCPC 87.5%, and 81.3% in patients undergoing fenestrated procedures. Two of three patients survived perioperative Fontan take-down. We lost 11 patients (nine early and two late deaths): three patients died primarily because of neurologic dysfunction and eight patients because of cardiac failures. Under perioperative NO therapy there was no early death. After a mean follow-up of 35.9 +/- 23.3 months, 76% of all patients were in NYHA I and 21 % in NYHA I-II. 89.7% had sinus rhythm. 42% of our patients suffered from temporary pleuropericardial effusions. CONCLUSIONS: Definitive palliation with TCPC achieves acceptable clinical results. Two-stage repair, fenestration, and postoperative inhalative NO therapy - each have a positive influence on early and long-term survival.

Minimally invasive versus conventional aortic valve operations: a prospective study in 120 patients.

BACKGROUND: Risk evaluation comparing the minimally invasive and standard aortic valve operations has not been studied. METHODS: Four surgeons were randomly assigned to perform the minimally invasive (L-shaped sternotomy) (group 1) or the conventional (group 2) operation in 120 patients exclusively. RESULTS: In both groups (n = 60) a CarboMedics prothesis was implanted in 90% of patients. There was no significant difference in the cross-clamping period (group 1, 60 minutes; range, 35 to 116 minutes), in the duration of extracorporal circulation (group 1, 84 minutes; range, 51 to 179 minutes) or in the time from skin-to-skin (group 1, 195 minutes; range, 145 to 466 minutes). Patients in group 1 were extubated earlier (p<0.001), the postoperative blood loss was less (p<0.001), and the need for analgesics was reduced (p<0.05). In 5 patients in group 1 a redo operation was required for bleeding (p>0.05), 3 patients in group 1 required a redo operation because of paravalvular leakage or endocarditis (p>0.05), the 30-day mortality rate was 1.6%. Overall the survival rate was 95% in group 1 and 97% in group 2 (mean follow-up, 294 days; range, 30 to 745 days). CONCLUSION: The advantages of minimally invasive aortic valve operation include reduced trauma from incision and duration of ventilation, decreased blood loss and postoperative pain, the avoidance of groin cannulation, and a cosmetically attractive result. Simple equipment is used with a high degree of effectiveness and with no sacrifice of safety. Our study demonstrated the practicability and reliability of this new method.

Effects of inhaled nitric oxide during permissive hypercapnia in acute respiratory failure in piglets.

OBJECTIVE: To look for the effects of inhaled nitric oxide on oxygenation and pulmonary hemodynamics during acute hypercapnia in acute respiratory failure. DESIGN: Prospective, randomized, experimental study. SETTING: University research laboratory. SUBJECTS: Ten piglets, weighing 9 to 13 kg. INTERVENTIONS: Acute respiratory failure was induced by oleic acid infusion and repeated lung lavages with 0.9% sodium chloride. The protocol consisted of three randomly assigned periods with different PaCO2 levels. Tidal volume was reduced to induce hypercapnia. Inspiratory time was prolonged to achieve similar mean airway pressures. During permissive hypercapnia, pH was not corrected. At each PaCO2 period, the animals were ventilated with inhaled nitric oxide of 10 parts per million and without nitric oxide inhalation. MEASUREMENTS AND MAIN RESULTS: Continuous hemodynamic monitoring included right atrial, mean pulmonary arterial, and mean systemic arterial pressures, arterial and mixed venous oxygen saturations, and continuous flow recording at the pulmonary artery. In addition, airway pressures, tidal volumes, dynamic lung compliance and airway resistance, end-tidal CO2 concentrations, and arterial and mixed venous blood gases were measured. Data were obtained at baseline and after lung injury, at normocapnia, at two levels of hypercapnia with and without nitric oxide inhalation. Acute hypercapnia resulted in a significant decrease in blood pH and a significant increase in mean pulmonary arterial pressure. There was no significant change in PaO2 during normocapnia and hypercapnia. Inhaled nitric oxide significantly decreased the mean pulmonary arterial pressure during both hypercapnic periods. It significantly improved oxygenation during both normocapnia and hypercapnia. CONCLUSIONS: Acute hypercapnia resulted in a significant increase in pulmonary arterial pressure without influencing oxygenation and cardiac output. Inhaled nitric oxide significantly reduced the pulmonary hypertension induced by acute permissive hypercapnia but did not influence the flow through the pulmonary artery. Inhaled nitric oxide significantly improved oxygenation in this model of acute lung injury during normocapnia and acute hypercapnia.

Inhaled nitric oxide in infants and children after open heart surgery.

OBJECTIVE: To assess the effects of inhaled nitric oxide (NO) on oxygenation and pulmonary circulation in infants and children with critical pulmonary perfusion and/or hypoxemia after open heart surgery. STUDY: A prospective case series report. SETTING: A multidisciplinary pediatric intensive care unit in a University hospital PATIENTS: From June 1993 to March 1996 37 pediatric patients after open heart surgery were treated with inhaled NO. Their mean age was 2.9+/-0.6 years, their mean body weight 12.6+/-1.8 kg. METHODS: Inhaled NO was applied using a microprocessor controlled delivery system which continuously measured NO and NO2 by the chemilumniscence method. Monitoring included ECG, continuous pulse oximetry (SaO2), arterial (AP), central venous (CVP) and left atrial (LAP) pressures and in 8 patients a pulmonary artery (PAP) pressure. Inhaled NO was started at an SaO2 <90% with a fraction of inspired oxygen concentration (FiO2) >0.7, at a mean pulmonary artery pressure (MPAP) >50% of the mean arterial pressure (MAP), and in patients after Fontan-procedure at a CVP-LAP pressure gradient >10 mmHg. RESULTS: The mean dose of inhaled NO was 3.7+/-0.3 ppm and the mean duration was 112+/-14.7 hours. For the whole group SaO2 increased from 79.6+/-2.3 to 90.1+/-1.5% (p<0.01) within 20 minutes of NO-inhalation. Inhaled NO significantly decreased the MPAP from 47.8+/-4 to 27.5+/-2.3 mmHg (p<0.01) in 8 patients with postoperative pulmonary hypertension and significantly decreased the transpulmonary pressure (CVP-LAP) from 14.3+/-0.8 to 7.3+/-0.9 mmHg (p<0.01) in 16 patients after Glenn- or Fontan-procedure. CONCLUSIONS: Inhaled NO is very effective to decrease pulmonary artery pressure, to improve oxygenation, and to improve Fontan-circulation in infants and children after open heart surgery.

[Accessory mitral valve tissue as a rare cause of subaortic stenosis and valvular aortic insufficiency]. / Akzessorisches Mitralklappengewebe als seltene Ursache einer Subaortenstenose und valvulären Aorteninsuffizienz.

An unusual case of subaortic stenosis and aortic regurgitation caused by accessory mitral valve tissue in a 10 year old boy is reported. Two-dimensional and Doppler echocardiography revealed the characteristic feature of a mobile, parachute-like mass in the left ventricular outflow tract pro-lapsing into the aortic valve during systole and, thus, producing a systolic pressure gradient of 70 mm Hg between the left ventricle and aorta and causing mild aortic regurgitation. The accessory valve tissue was completely excised via an aortotomy without injury to the normal mitral and aortic valves. Two dimensional echocardiography provides excellent morphological information about the relationship between the accessory mitral valve tissue and the mitral and aortic valves, respectively. Accurate preoperative evaluation by two-dimensional echocardiography facilitates the successful surgical management of this rare condition.

Inhaled nitric oxide in patients with critical pulmonary perfusion after Fontan-type procedures and bidirectional Glenn anastomosis.

OBJECTIVE: The aim of this study was to evaluate the effects of inhaled nitric oxide in patients with critical pulmonary perfusion after Fontan-type procedures and bidirectional Glenn anastomosis. METHODS: Inhaled nitric oxide (mean 4.1 +/- 0.7 ppm, 1.5 to 10 ppm) was administered in 13 patients (mean age 5.6 +/- 1.6 years, 1.5 to 17 years) with critical pulmonary perfusion (central venous pressure > 20 mm Hg or transpulmonary pressure gradient > 10 mm Hg) in the early postoperative period after total cavopulmonary connection (n = 9) or after bidirectional Glenn anastomosis (n = 4). RESULTS: In patients after total cavopulmonary connection inhaled nitric oxide therapy decreased central venous pressure by 15.3% +/- 1.4% (p = 0.0001) and transpulmonary pressure gradient by 42% +/- 8% (p = 0.0008) and increased mean systemic arterial and left atrial pressures by 12% +/- 3.6% (p = 0.011) and 28% +/- 8% (p = 0.007), respectively. Arterial and venous oxygen saturations improved by 8.2% +/- 1% (p = 0.005) and 14% +/- 4.3% (p = 0.03), respectively. In patients after bidirectional Glenn anastomosis inhaled nitric oxide therapy resulted in a decrease of central venous pressure by 22% +/- 1% and of the transpulmonary pressure gradient by 55% +/- 6% and improved arterial and venous oxygen saturations by 37% +/- 29% and 11% +/- 3%, respectively. Mean systemic arterial and left atrial pressures remained nearly unchanged. No toxic side effect was observed in any patient. CONCLUSION: Inhaled nitric oxide may play an important role in the management of transient critical pulmonary perfusion caused by reactive elevated pulmonary vascular resistance in the early postoperative period after Fontan-type operations and bidirectional Glenn anastomosis.

Assessment of lung function in neonates during extracorporeal membrane oxygenation.

We report our experience with pulmonary function testing in 11 out of 22 full-term neonates with severe respiratory failure, treated at the ECMO center Graz (Austria) during the period from 1990 to 1995. Altogether 17 out of 22 patients survived ECMO and all of them were successfully weaned from ECMO. Pulmonary function was assessed by monitoring expiratory tidal volume on the ventilator and estimating respiratory system compliance from the ratio tidal volume/(PIP-PEEP). In addition, compliance, and functional residual capacity were measured using a computerized pulmonary function system (PEDS). Compliance (mean +/- SD) decreased markedly after 24 hours of ECMO, compared with baseline values (0.20 +/- 0.12 vs 0.12 +/- 0.13 ml/cmH2O/kg) and was significantly higher (0.43 +/- 0.14 ml/cmH2O/kg, p < 0.01) before ECMO stop. When tidal volumes increased continuously ECMO blood flow could be decreased, indicating lung recovery. Most patients had a tidal volume of > 7 ml/kg prior to decannulation. Functional residual capacity and corresponding dynamic compliance, measured in 5 patients, ranged from 18.6 to 29.6 ml/kg and 0.49 to 0.57 ml/cmH2O/kg at this time. Functional residual capacity (mean +/- SD) increased significantly when surfactant was administered to promote weaning from ECMO (8.28 +/- 0.9 vs 19.0 +/- 1.0 ml/kg, p < 0.01). We conclude that the assessment of lung function has improved our understanding of pulmonary recovery during ECMO. Its clinical significance in determining the optimum time of weaning from ECMO needs further evaluation.

Partial liquid ventilation combined with inhaled nitric oxide in acute respiratory failure with pulmonary hypertension in piglets.

This study was a prospective, randomized, controlled design to evaluate gas exchange, lung mechanics, and pulmonary hemodynamics during partial liquid ventilation (PLV) combined with inhaled nitric oxide (NO) in acute respiratory failure (ARF) with pulmonary hypertension (PH). ARF with PH was induced in 12 piglets weighing 9.7-13.7 kg by repeated lung lavages and the continuous infusion of the stable endoperoxane analog of thromboxane. Thereafter the animals were randomly assigned either for PLV or conventional mechanical ventilation (CMV) at a fractional concentration of inspired O2 (Fio2) of 1.0. Perfluorocarbon (PFC) liquid (30 mL kg-1) was instilled into the endotracheal tube over 5 min followed by 5 mL kg-1h-1. All animals were treated with different concentrations of NO (1-10-20 ppm) inhaled in random order. Continuous monitoring included ECG, right atrial (Pra), mean pulmonary artery (Ppa), pulmonary capillary (Ppc'), and mean arterial (Pa) pressures, arteria oxygen saturation, and mixed venous oxygen saturation measurements. During PLV Pao2/Fio2 increased significantly from 8.2 +/- 0.4 kPa to 34.8 +/- 5.1 kPa (p < 0.01), whereas Pao2/FiO2 remained constant at 9.5 +/- 0.4 kPa during CMV. The infusion of the endoperoxane analog resulted in a sudden decrease of Pao2/Fio2 from 34.8 +/- 5.1 kPa to 14.1 +/- 0.4 kPa (p < 0.01) in the PLV group and from 9.5 +/- 0.4 kPa to 6.9 +/- 0.2 kPa (p < 0.05) in the control group. Inhaled NO significantly improved oxygenation in both groups (Pao2/Fio2: 45.7 +/- 5.3 kPa during PLV and 25.9 +/- 4.7 kPa during CMV). During inhalation of NO mean Ppa decreased significantly from 7.8 +/- 0.26 kPa to 4.2 +/- 0.26 kPa (p < 0.01) in the PLV group and from 7.4 +/- 0.26 kPa to 5.1 +/- 0.13 kPa (p < 0.01) in the control group. As documented in the literature PLV significantly improves oxygenation and lung mechanics in severe ARF. In addition, when ARF is associated with severe PH, the combined treatment of PLV and inhaled NO improves pulmonary hemodynamics resulting in better oxygenation.

Venous thrombosis in and after extracorporeal membrane oxygenation: detection and follow-up by color Doppler sonography.

The purpose of our study was to evaluate thrombosis of venous vessels during and after extracorporeal membrane oxygenation (ECMO) using color Doppler sonography. We prospectively performed serial color Doppler sonography investigations in 30 ECMO patients [age: newborn to 3 years, male:female = 20:10, venoarterial (VA) ECMO = 18, venovenous (VV) ECMO = 12]. During ECMO obstruction and/or thrombosis of the superior vena cava (SVC) was observed in 2 neonates on VA ECMO. Furthermore, a thrombotic clot from an initially open duct of Arantii with partial portal vein thrombosis, reaching into the inferior vena cava (IVC), occurred despite adequate heparinization. After ECMO, late septic SVC thrombus occurred in one neonate. IVC thrombus was observed in two pediatric VV ECMO patients. The overall incidence of venous clots was 20 % (6 of 30). Routine color Doppler sonography monitoring of vessels in children on and after ECMO was found to be useful for early detection of venous thrombosis. It enabled consequent administration of appropriate therapy as well as follow-up after decannulation and reconstruction.

Activation of the clotting system: heparin-coated versus non coated systems for extracorporeal circulation.

UNLABELLED: The purpose of this experimental study was to compare heparin-coated versus non-coated systems for extracorporeal membrane oxygenation (ECMO), to investigate the dynamic course of clotting activation in both groups. METHODS: Eight pigs weighing 19.7 (+/- 1.3) kg, each underwent ECMO for 24 hours. Two groups were formed: in group 1, heparin-coated circuits were used with low dose heparinization (10 IU/kg/hr), whereas in group 2 non-coated circuits with high dose heparinization (60 IU/kg/hr) were used. Coagulation was monitored by measuring prothrombin time, partial thromboplastin time, fibrinogen, antithrombin III (AT III) and specific markers of clotting activation (thrombin-antithrombin III complexes (TAT) and D-dimer). Furthermore, platelet count, hematocrit, activated clotting time (ACT), and plasma heparin concentration were determined regularly RESULTS: The dynamic course of the specific coagulation activation markers showed some differences: whereas TAT and D-dimer increased quickly in group 2, the increase in group 1 was delayed. Activation marker values tended to be lower in group 1 during the first six hours, after which no more differences between the groups were seen. After 24 hours of ECMO, TAT and D-dimer had nearly returned to baseline values. Platelets showed a continuous decrease throughout the experiment, which was very similar in both groups. CONCLUSIONS: The heparin coated system showed a distinct delay in clotting activation during the first six hours of ECMO. After six hours there were no more differences between the groups.

Concomitant procedures in the small versus standard aortic root.

BACKGROUND AND AIMS OF THE STUDY: Aortic valve replacement (AVR) in the small aortic root (SAR) has always been a severe challenge with an uncertain surgical outcome. The purpose of this study was to assess the surgical and clinical performance of 19 mm and 21 mm CarboMedics valves (CPHV) based on a review of valve-related morbidity and mortality over a period of six years. METHODS: A total of 361 patients undergoing aortic valve replacement (AVR) with the CPHV between January 1989 and August 1995 was subdivided and studied. (i) Group A patients (n = 137) received 19 mm or 21 mm prostheses; subgroup AI (n = 85) underwent isolated AVR and subgroup AII (n = 52) underwent AVR with associated cardiac procedures. (ii) Group B patients (n = 224) were given 23 mm or larger prostheses; subgroup BI (n = 147) underwent isolated AVR and subgroup BII (n = 77) underwent AVR with concomitant cardiac procedures. RESULTS: Hospital mortality was group A 7.3% versus group B 4.9%. Cumulative survival after six years was 83.7% in AI and 76.9% in AII versus 72.1% in BI and 77.4% in BII. There were no significant statistical differences between the subgroups concerning cardiac mortality. Thromboembolic events occurred with a linearized rate of 1.41%/pty in group A versus 1.03%/pty in group B, the incidence of anticoagulant-related major hemorrhage was 1.41%/pty in group A versus 1.20%/pty in group B and that of periprosthetic leakage 1.69%/pty in group A versus 1.89%/pty in group B. CONCLUSION: Our results demonstrate that this bileaflet prosthesis is highly efficient in patients with small aortic roots undergoing AVR with or without associated procedures.

Activation of the clotting system during extracorporeal membrane oxygenation in term newborn infants.

OBJECTIVES: To determine the degree of clotting activation that occurs with the usual anticoagulation regimen with systemic heparinization. METHODS: To allow a standardized comparison of the patients, this study focused on the first 48 hours of extracorporeal membrane oxygenation (ECMO) in term newborn infants. The ECMO perfusion circuit consisted of a roller pump, silicone membrane lungs, and silicone rubber tubing. Coagulation was controlled routinely by measuring prothrombin time, fibrinogen, antithrombin III, and reptilase time. Platelet counts, activated clotting time, and heparin concentration were controlled regularly. The following specific activation markers of the clotting system were measured: prothrombin activation fragment 1 + 2(F1+2), thrombin-antithrombin III complexes, and D-dimer. Measurements were done before the start of ECMO, after 5 minutes, and at hours 1, 2, 3, 4, 6, 12, 24 and 48. RESULTS: All seven term infants had excessively high levels of clotting activation markers within the first 2 hours of ECMO: F1+2, 11.6(+/- O.9) nmol/L (mean +/- SEM); thrombin-antithrombin, 920(+/- 2.2) microg/L; D-dimer, 15.522(+/- 3.689) ng/L. During the next 46 hours of ECMO, F1+2 and thrombin-antithrombin III complexes decreased from those high values, whereas D-dimer did not. The increase of activation markers was accompanied by low fibrinogen, low platelet counts. and prolongation of reptilase time. CONCLUSIONS: These findings fit the pattern of consumptive coagulopathy during neonatal ECMO, especially in the first 24 hours.