Comparison of conventional extracorporeal circulation and minimal extracorporeal circulation with respect to microbubbles and microembolic signals.

The intention of minimal extracorporeal circulation (MECC) is to reduce priming volume and minimize contact of blood with polymers and air in a closed system. In contrast to conventional extracorporeal circulation (ECC), a venous reservoir is missing. Thus, air trapping is limited and avoidance of bubble embolism is a major concern. This study investigates microbubbles (MBB) number and size in the venous and arterial lines of ECC and MECC compared to the number of microembolic signals (MES) in the right and left middle cerebral artery (MCA). Twenty patients undergoing coronary surgery were operated either with conventional ECC (cardiotomy reservoir, Rotaflow pump, Quadrox oxygenator, Quart filter) or MECC (Quart filter, Rotaflow pump, Quadrox oxygenator). Number and size of MBB were monitored in the venous and arterial lines with an ultrasound Doppler system. MES in right and left MCAs were measured by transcranial Doppler (TCD) monitoring. Patients undergoing MECC had additional sealing of the venous cannula by a ligature at the site of its insertion into the right atrium. There were no significant differences between groups with respect to age, X-clamping, bypass time and number of distal anastomoses. The number of MES and MBB in the arterial line was comparable between the groups. On the venous side, MECC-perfusion shows a significantly lower number of MBB. This could be explained with the additional sealing of the venous cannula. Furthermore, our data indicate that the MBB-volume reaching the pump will also appear in the arterial outflow and into the patient's MCA. For this reason, the avoidance of air contamination is a major concern for surgeons, anaesthesiologists and perfusionists.

Discriminative stimulus function of ethanol: role of GABAA receptors in the nucleus accumbens.

Because the subjective effects of drugs may be related to abuse potential, this study was conducted to assess the involvement of GABAA receptor systems in the nucleus accumbens (N Acc) in the discriminative stimulus effects of ethanol. Male Long-Evans rats were trained to discriminate between intraperitoneal (IP) injections of ethanol (1 g/kg) and saline under a fixed-ratio 10 schedule of sucrose (10% w/v) reinforcement. When performance during training sessions met the accuracy criteria (> 80% correct responding for five consecutive days), an ethanol generalization curve was determined. The rats were then surgically implanted with bilateral stainless-steel guide cannulae aimed at the N Acc. Intra-accumbens (IA) substitution test sessions were conducted during which the direct GABAA agonist muscimol (0.01, 0.04, 0.10, and 0.40 micrograms/microliter; IA) was administered in combination with saline (IP). The direct GABAA antagonist bicuculline (0.03, 0.10, and 0.30 micrograms/microliter; IA) was administered in combination with the training dose of ethanol (1 g/kg, ip). At 10-min postinjection, IA muscimol partially substituted for IP ethanol. However, at 15-min postinjection, muscimol (0.10 microgram/microliter; IA) fully substituted for IP ethanol. Bicuculline attenuated the discriminative stimulus properties of IP ethanol, but only at doses that significantly decreased response rate. At 10-min postinjection, muscimol (0.01 and 0.04 micrograms/microliter) potentiated (> 80% ethanol lever responding) the discriminative stimulus properties of a dose of ethanol (0.5 g/kg) that alone produced only partial generalization. These data suggest that ethanol discrimination is mediated centrally and demonstrate that infusions of the GABAA agonist muscimol in the N Acc are sufficient to produce the stimulus effects corresponding to a 1.0 g/kg training dose of ethanol. When taken together with data showing that GABAA receptor activation in the N Acc potentiates the termination of ethanol self-administration, these data suggest that ethanol's discriminative stimulus function may influence its reinforcement function.

Predictive criteria for the need of extracorporeal circulation in single-lung transplantation.

Use of extracorporeal circulation is mandatory in heart-lung and en bloc double-lung transplantation. However, no criteria exist to predict the necessity of its application during single-lung transplantation for parenchymal lung diseases. We therefore reviewed our experience in 23 patients undergoing single-lung transplantation for idiopathic pulmonary fibrosis. All patients were evaluated by preoperative right heart catheterization. For intraoperative monitoring, a pulmonary artery thermodilution catheter was placed in the contralateral lung to repeatedly assess pulmonary artery pressure, cardiac output, and pulmonary vascular resistance. Extracorporeal circulation was necessary during graft implantation in 4 patients, whereas 19 patients underwent operation without it. Preoperative demographic patient data, time of ischemia, and hemodynamic values obtained preoperatively and before the clamping of the pulmonary artery showed no significant differences between groups. In contrast, after the clamping of the pulmonary artery, a significant drop in cardiac index of about 1.5 L.min-1.m-2 (p less than 0.01) and a concomitant rise in pulmonary vascular resistance (p less than 0.01) was observed in the group requiring extracorporeal circulation, whereas these variables showed no significant changes in the other 19 patients. Pulmonary artery pressure rose significantly in both groups (p less than 0.05), without significant differences between them. It is concluded that intraoperative assessment of cardiac index and pulmonary vascular resistance is essential for estimation of cardiac performance during single-lung transplantation. A decrease in cardiac index of more than 1.5 L.min-1.m-2 after the clamping of the pulmonary artery rather than the degree of pulmonary hypertension is indicative of the need of extracorporeal circulation.

Decreased incidence of bronchial complications following lung transplantation.

Despite omental wrap and avoidance of prophylactic administration of corticosteroids in the early postoperative phase, ischemic bronchial complications still represent an important source of early morbidity and mortality following lung transplantation. In a retrospective analysis, the effect of pharmacological enhancement of pulmonary collateral flow on bronchial healing was investigated. Thirty-nine consecutive unilateral or bilateral transplant procedures (Tx) were analyzed. Immunosuppression consisted of rabbit antithymocyte globulin (RATG), cyclosporine A, and azathioprine. In group 1 (10 Tx, 12 anastomoses) routine immunosuppression was employed and the anastomoses wrapped with an omental or pericardial pedicle. In group 2 (29 Tx, 41 anastomoses) PGI2 (4 ng/kg per min x 48 h), heparin (200 U/kg per day), and prednisolone (0.5 mg/kg per day) were added to the therapeutic regimen. The 2 groups were comparable with respect to age and sex of the patients, primary diagnosis, type of transplant, intraoperative use of extracorporeal circulation, graft ischemia, duration of mechanical ventilation, and mortality. Bronchoscopic evidence of a significant bronchial ischemia (extending more than 1 cartilaginous ring beyond the anastomosis) was seen in 8 of 12 anastomoses in group 1 vs 14 of 53 anastomoses in group 2 (P = NS). In group 1, significant bronchial stenosis required implantation of an endobronchial silicone stent in 6 of 12 anastomoses, whereas in group 2, no significant bronchial stenosis occurred (P less than 0.01). No negative effects possibly related to the prophylactic administration of corticosteroids could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)

[Perioperative preventive antibiotic treatment with fosfomycin in heart surgery: serum kinetics in extracorporeal circulation and determination of concentration in heart valve tissue]. / Die perioperative Antibiotikaprophylaxe mit Fosfomycin in der Herzchirurgie: Serumkinetik unter extrakorporaler Zirkulation und Konzentrationsbestimmungen im Herzklappengewebe.

A prospective clinical study was carried out to assess the adequacy of perioperative antibiotic prophylaxis using fosfomycin in patients undergoing open-heart surgery for valve diseases for the prevention of early postoperative endocarditis, as well as for serious mediastinal infections that are caused mostly by multiresistant staphylococci and Gram-negative bacteria. Perioperative pharmacokinetics and tissue penetration were determined within the harvested heart valves and subcutaneous tissue. Reliable bactericidal serum levels were established at the first measurement 10 min after the end of intravenous infusion (203.7 +/- 44.7 micrograms/ml) and were maintained during surgery for at least 120 min (124.6 +/- 58.4 micrograms/ml), even in cases of prolonged extracorporeal circulation. Cardiopulmonary bypass did not alter the serum elimination of fosfomycin in comparison with patients not undergoing extracorporeal circulation. Peak tissue concentrations were achieved in both aortic and mitral valves after 30 min, ranging between 27.1 and 76.9 micrograms/g for aortic valves and 39.6-69.4 micrograms/g for mitral valves, depending on the degree of valvular degeneration. MIC values of 16 micrograms/g were maintained in both valves for at least up to 60 min. There was no evidence of renal impairment, adverse reactions or infections during the postoperative course or thereafter for a period of 3 months. It is concluded that perioperative intravenous antibiotic prophylaxis using fosfomycin (5 g t.i.d. in adults), beginning with induction of anesthesia and continued for 48 h postoperatively, provides rapid, reliable bactericidal serum levels and valvular tissue concentrations that will inhibit most Gram-positive and Gram-negative organisms that cause bacterial endocarditis and other serious infections following cardiac surgery.

[Unilateral lung transplantation]. / Unilaterale Lungentransplantation.

For patients with terminal pulmonary fibrosis unilateral lung transplantation offers a new therapeutic option. At the Hannover Medical School 5 patients have been successfully treated by single lung transplantation. In 3 patients a left, and in 2 patients a right lung transplant was performed. One patient required intraoperative support by cardiopulmonary bypass. Bronchial omentopexy was used in all instances. Currently all patients are alive. A marked improvement of pulmonary function parameters was seen in all cases. The patients are all able to lead a normal life.

[Anesthesiology experiences in 199 heart transplants]. / Anästhesiologische Erfahrungen bei 199 Herztransplantationen.

From June 1983 to October 1987 199 orthotopic heart transplantations were performed at the Medical School of Hannover. Eighty percent of the organs were explanted in foreign hospitals. Since the cold ischemic time lasts less than 4 hours, a sophisticated transport system is essential. The selection of donors (dissociated brain death, age less than 35 years, systolic blood pressure greater than 70 mm Hg, intensive care for less than 7 days) and recipients (age between 10 and 55 years, final stage of irreversible myocardial insufficiency) is governed by strict criteria. A fixed pulmonary hypertension of more than 8 Wood is an absolute contraindication. The pulmonary wedge pressure and the right atrial pressure are preoperatively raised more than three times from normal. The ejection fraction is reduced to 10%. Seventy percent of the patients suffer from dilated cardiomyopathy. The premedication with flunitrazepam is given orally. Anaesthesia is induced with fentanyl and etomidate followed by pancuronium for intubation. During the time of induction all lines have to be inserted under sterile conditions. For weaning from the heart lung machine always catecholamines (isoproterenol, adrenaline) are applied in combination with vasodilators (nitroglycerin, DHB). Postoperatively patients will be extubated after 17.8 +/- 2.2 hours. Rejection episodes belong to the most threatening sort of complications. For this reason endomyocardial biopsies are done routinely.

Carotid endarterectomy: neurologic complications as related to surgical techniques.

Three hundred seventeen carotid endarterectomies performed on 240 consecutive patients in four Charleston hospitals were reviewed. The overall incidence of stroke was 10.7% and the mortality 3.2%. From these 317 operations a standardized series of 253 operations performed on neurologically stable patients was analyzed for neurologic complications as related to the use of an intra-operative shunt. Additional factors studied were length of time of carotid occlusion and degree of contralateral carotid stenosis. From the standardized series the incidence of stroke in 137 shunted cases was 9.5%, and in 116 non-shunted cases was 0.9%, a significant difference (p less than 0.01). Carotid artery occlusion times from 30 seconds to 12 minutes in the shunted group, and three minutes to 24 minutes in the non-shunted group had no relationship to the incidence of stroke. Significant contralateral carotid artery stenosis, present in 28/137 shunted cases and 30/116 non-shunted cases, had no predictive value in the development of a stroke. The use of an intra-operative shunt did not protect against stroke in these patients.