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.

Prolonged extracorporeal organ support in a 2-year-old boy after cardiac surgery.

A case report of a 2-year-old boy who developed severe post-operative low cardiac output, sudden cardiac arrest and consecutive multiple organ system failure after open heart surgery is described. Initially the hemodynamic situation was stabilized by extracorporeal membrane oxygenation (ECMO) combined with continuous hemofiltration (CHF) carried out for 7 days. Continuous veno-venous hemofiltration (CVVH) was necessary for further 17 days. One episode of plasmapheresis restored transiently a severe post-operative coagulopathy and enabled the removal of the pulmonary artery catheter and the chest tubes.

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.

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.

Proximal and tracheal airway pressures during different modes of mechanical ventilation: an animal model study.

OBJECTIVE: To determine the differences between the mean proximal and tracheal airway pressures during 3 different modes of mechanical ventilation (MV) in an animal model of acute cardiac failure (CF) and respiratory failure (RF). DESIGN: Prospective, randomized, cross-over design. SETTING: University research laboratory. SUBJECTS: Twelve young pigs weighing 10-16 kg. INTERVENTIONS: The experimental protocol consisted of 3 stable 30 min conditions: when ventricular and pulmonary function was normal (control), after the induction of acute cardiac failure by a beta-blocking agent and after respiratory failure induced by repeated lung lavages. Modes of MV included controlled mechanical ventilation (CMV), high-frequency oscillation (HFO), and high-frequency jet ventilation (HFJV). MEASUREMENTS AND RESULTS: The tracheal mean airway pressure (P(aw)) was measured at the distal port of the Hi-lo jet tube using an air-filled pressure transducer. The mean transpulmonary P(aw) increased significantly from 0.41 +/- 0.14 kPa during the control period to 1.15 +/- 0.17 kPa (P < 0.0001) during the RF period. In all study periods both the proximal and tracheal P(aw) were lowest during HFJV. There was no difference between the proximal and tracheal P(aw) during CMV and HFJV throughout the protocol. In the cardiac and respiratory failure periods the proximal P(aw) (CF, 1.45 +/- 0.08 kPa; RF, 3.13 +/- 0.27 kPa) was significantly higher than the tracheal P(aw) (CF, 1.04 +/- 0.09 kPa, P < 0.01; RF, 2.18 +/- 0.3 kPa, P < 0.01) with HFO. When ventilated by HFO, the mean external oscillatory amplitude was 4.33 +/- 0.14 kPa and the intratracheal oscillatory amplitude was only 0.49 +/- 0.06 kPa (P < 0.0001). CONCLUSION: HFJV provides adequate respiratory support at lower P(aw) than CMV and HFO. Proximal P(aw) closely reflects tracheal P(aw) during CMV and HFJV. However, with HFO great pressure differences between the proximal and tracheal airways are evident. Therefore, additional intratracheal airway pressure monitoring seems to be very useful for optimizing ventilator settings during HFO.

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.

Twenty-four years' implant duration of the aortic Starr-Edwards Silastic ball prosthesis: a valve of the past?

Six years after the first aortic valve replacement with the Starr-Edwards Silastic ball prosthesis at Oregon Health Sciences University, the model 1260 was implanted in a 44-year-old patient at our department. During 24 years no signs of dysfunction, thromboembolism, thrombosis, periprosthetic leaks or hemolysis were observed. Material test showed no signs of fatigue. The dimension of the Silastic poppet was found to be one millimeter less than the original specifications of these poppets and there were some lipid infiltrations. Functionally the poppet was found to be nonvariant. Histologic findings detected focal hyalinization and giant cells without signs of acute inflammation or ulceration. With regard to its reliability and durability, the Starr-Edwards valve prosthesis should not be viewed with disfavor.

Prospective evaluation of clinical scoring systems in infants and children with cardiopulmonary insufficiency after cardiac surgery.

OBJECTIVE: To document severity of illness and to evaluate the predictive value of clinical scoring systems in infants and children with cardiopulmonary insufficiency after cardiac surgery. DESIGN: Prospective study with follow up to hospital discharge. SETTING: A multidisciplinary pediatric ICU in a University Hospital. PATIENTS: Between 1/1989 and 4/1992 441 infants and children with congenital heart disease underwent open heart surgery. 128 of these patients developed postoperative cardiopulmonary insufficiency and were entered into this study. METHODS: Data relevant to the Acute Physiologic Score for Children (APSC), Pediatric Risk of Mortality (PRISM), Therapeutic Intervention Scoring System (TISS) and Organ System Failure (OSF) score were collected in all patients during the first 4 days of postoperative intensive care. RESULTS: The mean age of the patients was 1.5 +/- 0.2 years. The mean duration of mechanical ventilation and ICU care was 6.2 +/- 0.6 and 8.1 +/- 0.7 days, respectively. On the first postoperative day the mean APSC and PRISM scores of survivors and nonsurvivors were 13.9 +/- 1.3 vs 24.5 +/- 1.3 (p < 0.001) and 6.1 +/- 0.5 vs 19.6 +/- 1.9 (p < 0.001), respectively. The mean TISS and OSF scores of survivors and nonsurvivors were 46 +/- 0.8 vs 57.8 +/- 1.4 (p < 0.001), and 2.2 +/- 0.2 vs 3.4 +/- 0.2 (p < 0.001), respectively. The overall hospital mortality rate was 9.9%, the hospital mortality rate of patients with postoperative cardiopulmonary insufficiency 34%. Patients with an APSC score < 10 and a PRISM score < 5 had a survival rate of 100%, whereas patients with an APSC score > 30 and a PRISM score > 25 had a mortality rate of 100%. The area under the receiver operating characteristic (ROC) curve for APSC, PRISM and TISS was 0.847, 0.826 and 0.793, respectively. CONCLUSION: APSC, PRISM and TISS describe accurately severity of illness in infants and children with cardiopulmonary insufficiency after cardiac surgery and all scores identify those patients at increased risk for mortality.

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.

Mechanical support of the left ventricle in ischemia induced left ventricular failure: an experimental study.

OBJECTIVE: this study compares the hemodynamic effects of intra-aortic balloon pumping (IABP), left ventricular assist device (LVAD), and extracorporeal membrane oxygenation (ECMO) in left ventricular failure in pigs. METHODS: In 29 pigs weighing 12 +/- 0.7 kg left ventricular failure was induced by ligating the left anterior descending coronary artery. Eight animals served as controls. Eight pigs were treated by IABP, seven by LVAD, and six by ECMO. The study period lasted four hours. Hemodynamic and oxygen transport/uptake parameters were measured continuously or intermittently. RESULTS: Six animals of the ECMO and LVAD groups survived the 4 hour period, but only 3 and 4 animals of the IABP and control groups survived (p less than 0.05). Cardiac index decreased about 48% and 22% in the control and IABP groups (p less than 0.05), whereas there was only a slight decrease in the ECMO (9%) and LVAD (14%) groups. Oxygen delivery fell significantly in the control and IABP groups (p less than 0.05), compared with only a slight change in the LVAD and ECMO groups. CONCLUSION: ECMO is the most effective system for temporary circulatory support in severe ventricular failure. LVAD maintains cardiac output when pulmonary blood flow is provided. IABP is less efficient in supporting the failing heart, especially in the presence of severe ventricular arrhythmias.

Extracorporeal CO2 removal in a lung lavage induced respiratory distress syndrome.

Ten pigs with experimental respiratory distress syndrome were treated by extracorporeal CO2 removal (ECCO2-R) combined with low frequency positive pressure ventilation (LPPV). After lung damage had been induced by repeated lung lavages a PEEP trial was conducted in order to find the appropriate PEEP for the damaged lungs. This PEEP was then applied during the ECCO2-R/LPPV period. Blood gas values improved significantly on extracorporeal bypass within a short time (pre-bypass paO2: 54.2 +/- 3.7 vs 168.5 +/- 31.6 mmHg after 15 min on bypass, p less than 0.001) and were kept constant during the next 4 hours. Minute ventilation (MV) was reduced from 4.01 +/- 0.31 to 0.74 +/- 0.07 l/min (p less than 0.0001), FiO2 of the ventilator from 1.0 to 0.46 +/- 0.08 (p less than 0.0001) whereas FiO2 of the membrane lung (ML) was not changed significantly (FIO2ML 0.59 +/- 0.07 vs 0.53 +/- 0.06). During controlled mechanical ventilation (CMV), comparable adequate gas exchange was only achieved at a significantly higher mean airway pressure (Paw 14.1 +/- 0.08 vs 21.2 +/- 0.47 cmH20, p less than 0.0001). Hemodynamic variables did not change significantly during bypass time. ECCO2-R/LPPV driven by a simple renal perfusion system allows adequate gas exchange in experimental respiratory failure.

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.

[Open heart surgery in Jehovah's Witnesses]. / Offene Herzoperationen bei Zeugen Jehovas.

Patients who are Jehovah's Witnesses present a special problem when undergoing open heart surgery since they refuse blood transfusion. We performed 15 open heart operations for both acquired and congenital heart disease using a modified version of isovolaemic haemodilution and bloodless prime technique of extracorporeal circulation. Two patients died. One death might have been at least indirectly related to the regimen which excludes blood substitution. We believe that our experience demonstrates the feasibility of open heart procedures in Jehovah's Witnesses, although the mortality risk is increased in these patients.

[Total cavo-pulmonary connection as a therapeutic principle in anatomical and functional univentricular heart]. / Die totale cavo-pulmonale Konnektion als therapeutisches Prinzip bei anatomisch und funktionell univentrikulären Herzen.

The original Fontan operation was employed for patients with tricuspid atresia, but its application has been extended to a broad spectrum of congenital cardiac defects with a functional or anatomical single ventricle. From 1989 to 1995, 35 patients (23 males, 12 females) underwent a modified Fontan procedure; their age ranged from 14 months to 15 years (mean 5.1 a). Indications for operation were the following: D(S)ILV = 16, TA = 9, MA = 3, TGA with straddling AV-valve = 2, DORV = 4 and criss-cross heart = 1. The same surgical technique was utilized in all patients with redirection of the systemic venous return by means of a bidirectional cavopulmonary anastomosis and an intraatrial baffle, adaptable to all the various forms of underlying anatomy. Associated anomalies such as dextrocardia, coarctation, anomalous systemic or pulmonary venous return, subaortic stenosis and situs anomalies were present in 26%, 9%, 26%, 9%, and 20%, respectively. 12 patients were presumed to be at high risk and underwent a two-stage procedure (n = 7 bidirectional Glenn preceding the definitive repair and n = 5 a fenestration of the intraatrial baffle). Risk factors in our group of patients were: age under 2 years, abnormal systemic venous drainage, stenotic pulmonary arteries, PVR over 2 Wood units, mPAP over 15 mmHg, AV-valve incompetence, subaortic obstruction and ventricular dysfunction. Two patients had failure of the total cavo-pulmonary connection necessitating the take-down to a bidirectional Glenn anastomosis in the early postoperative period, with one death. Hospital mortality was 24% (n = 8). One child did not survive complications following the fenestration closure 4 months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

[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.

[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.

Continuous blood density measurements and volume changes during extracorporeal circulation in patients undergoing cardiac surgery.

The changes of blood volume and transcapillary fluid shifts during extracorporeal circulation (ECC) was examined using continuous measurements of blood density by the mechanical oscillator technique. Sixteen patients (1 female, 15 male) with a mean age of 61.4 years (+/- 7.6 years, 47-70 years) undergoing coronary artery bypass surgery were included in this study. The equipment for continuous measurement of the blood density (DPRT by Paar/Austria) was installed at the arterial line of the heart-lung bypass. Higher-precision discrete measurements of some parameters used the DMA 55 equipment produced by the Paar company. Measurements were taken at 37 degrees C. In 11 patients the transcapillary volume loss (difference of total volume between beginning and end of ECC) during heart-lung bypass (mean observation period of 55 min (+/- 16 min, 28-82 min) was found to be 870 ml/m2 body surface area (BSA) (+/- 360 ml, 290-1560 ml/m2) by the dilution method using the priming solution at the beginning and 500 ml lactated Ringer's solution added at the end of the ECC. The calculated volume shift using the "double density method", which takes into account blood density, plasma density, and hematocrit, amounted to 830 ml/m2 BSA (+/- 200 ml, 450-1210 ml/m2). The density of the transcapillary volume loss into the interstitial layer was calculated and found to be 1.0026 g/ml (+/- 0.0017 g/ml, 1.0003-1.0063 g/ml). A significant difference of transcapillary volume shift correlated with the administered catecholamine (dopamine, dobutamine) dosage postoperatively. Without catecholamine this difference was 260 ml/m2 BSA, with 3 microns/kg/min dopamine it rose to > 500 ml/m2 BSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic effects of different modes of mechanical ventilation in acute cardiac and pulmonary failure: an experimental study.

OBJECTIVE: To determine the hemodynamic effects of four different modes of mechanical ventilation in an animal model of acute cardiac and pulmonary failure. DESIGN: Prospective, randomized, crossover design. SETTING: University research laboratory. SUBJECTS: Twelve piglets weighing 10 to 16 kg. INTERVENTIONS: The experimental protocol consisted of three stable 30-min periods: when ventricular and pulmonary functions were normal (control), after the induction of acute cardiac failure by the administration of a beta-adrenergic receptor blocker, and after pulmonary failure induced by repeated lung lavage. Modes of mechanical ventilation included controlled mechanical ventilation, high-frequency oscillation, synchronized high-frequency jet ventilation, and external negative pressure oscillation combined with pressure support ventilation. Each mode of respiratory support was randomly and sequentially applied to each animal with the assessment of cardiopulmonary function at the end of each period. MEASUREMENTS AND MAIN RESULTS: Continuous monitoring included electrocardiogram, right atrial, left ventricular end-diastolic, pulmonary arterial, intrathoracic aortic, arterial, esophageal, and transpulmonary pressures and arterial and mixed venous oxygen saturation measurements. In addition, cardiac output using the thermodilution technique was measured intermittently. Whereas in the control period cardiac index was significantly (p < .05) higher during synchronized high-frequency jet ventilation (193 +/- 19.3 mL/kg/min) than during controlled mechanical ventilation (151 +/- 12.1 mL/kg/min) and high-frequency oscillation (151 +/- 18.1 mL/kg/min), there was no significant hemodynamic difference between the four modes of mechanical ventilation in the cardiac and pulmonary failure periods. In the pulmonary failure period, transpulmonary pressure was significantly higher during high-frequency oscillation (7.1 +/- 1.6 mm Hg) than during controlled mechanical ventilation (5.6 +/- 0.6 mm Hg), high-frequency ventilation (4.1 +/- 0.4 mm Hg), and external negative pressure oscillation combined with pressure support ventilation (5.3 +/- 0.5 mm Hg). CONCLUSIONS: Synchronized high-frequency ventilation improves cardiac performance in control conditions. No hemodynamic difference is present between the four modes of mechanical ventilation in the cardiac and pulmonary failure periods. External negative pressure oscillation combined with pressure support ventilation has moderate hemodynamic advantages over controlled mechanical ventilation and high-frequency oscillation in different clinical settings, but it also results in a deterioration of pulmonary gas exchange during the pulmonary failure period.