Jürgen Rötker

Diagnosis and Treatment of Nonocclusive Mesenteric Ischemia After Open Heart Surgery

BACKGROUND Acute nonocclusive mesenteric ischemia (NOMI) is a rare but often fatal event after cardiac surgery. METHODS Twenty patients with ongoing ileus after cardiac surgery despite maximal laxative treatment underwent selective mesenteric angiography. In cases of pathological radiographic findings, papaverine was continuously administered via an intraarterial perfusion catheter. RESULTS Severe NOMI was confirmed in seven patients (mean lactate: 6.9 +/- 8.3 mg/dL), mild to moderate findings in another seven (mean lactate: 1.4 +/- 1.1 mg/dL). One patient had thromboembolic occlusion of the superior mesenteric artery; five patients demonstrated normal imaging findings. In nine of fourteen patients (64%) treated with papaverine, symptoms improved within hours (defecation occurred after 4-29 hours, mean 13 +/- 8.1 hours). No side effects or complications occurred in connection with the papaverine treatment. The clinical condition of five patients deteriorated. Four patients underwent laparotomy with creation of an ileostomy or colostomy, two of whom presented with severe intestinal ischemia and later died. One patient died prior to laparotomy. CONCLUSIONS Selective mesenteric angiography with continuous papaverine administration is a simple, fast, and effective diagnostic and therapeutic tool to reduce the need for laparotomy for symptoms of ileus after open-heart surgery.

A new method for continuous intramucosal Pco2 measurement in the gastrointestinal tract

Gastric tonometry has been introduced for the early detection of impaired splanchnic perfusion by determination of the intramucosal PCO2.However, due to methodological problems, i.e., instability of CO2 in water, to assess the exact intramucosal PCO2 with the nasogastric tonometer is unreliable. The present in vitro and in vivo study examines a new fiberoptic PCO2 sensor for the continuous determination of the intramucosal PCO2 and compares these data with that of conventional tonometry. In an in vitro experiment the fiberoptic PCO2 sensor was used to determine the PCO2 of water and humidified air with predefined CO (2) values. In both media, predefined CO2 values (35, 42, 49 mm Hg) could be assessed exactly after 9 min of equilibration with a maximum deviation less than 3.5%. In contrast, the values obtained by conventional tonometry showed larger differences. In in vivo experiments on six pigs PCO2 differences were induced by ventilatory changes to validate the fiberoptic PCO2 sensor. Under anesthesia a laparotomy was performed, the ileum punctured, and the fiberoptic PCO2 sensor introduced into the ileal lumen. Arterial PCO2 (PaCO2), mesenteric venous PCO2 (PmvCO2), and intramucosal PCO2, (PiCO2) were determined during normoventilation, hypoventilation, and hyperventilation. During hypoventilation the PiCO2 increased from 53.8 +/- 2.0 mm Hg (PaCO2 = 39.8 +/- 1.4 mm Hg, PmvCO (2) = 48.7 +/- 2.7 mm Hg) to 66.5 +/- 4.9 mm Hg (PaCO2 = 52.7 +/- 3.1 mm Hg, PmvCO2 = 62.4 +/- 5.7 mm Hg). With hyperventilation the PiCO2 decreased to 46.8 +/- 2.5 mm Hg (PaCO2 = 29.8 +/- 1.8 mm Hg, PmvCO2 = 41.8 +/- 2.7 mm Hg). The coefficient of correlation (r2) between PiCO2 and PaCO2 was 0.82, and between PiCO2 and PmvCO2 0.94. The fiberoptic PCO2 sensor can determine PiCO2 in a precise and reliable manner, and can continuously record fast intraluminar changes of CO2 in the ileum that were caused by ventilatory changes. The fiberoptic PCO2 sensor is the only method that reliably monitors PiCO2 in the gastrointestinal tract. By the direct measurement of PCO2 the methodological problems associated with the conventional nasogastric tonometry are abolished. (Anesth Analg 1996;83:6-11)

Pheochromocytomas with extension into central vascular structures

Two cases of pheochromocytomas, 1 with extension into the inferior vena cava and the second with involvement of the right atrium, are reported. Both tumors were resected in toto, 1 using inferior to superior vena cava vein-to-vein bypass and the second with the aid of hypothermic circulatory arrest. Both patients are free of recurrences or metastasis 20 and 24 month postoperatively.

Effect of ventricular fibrillation duration on the defibrillation threshold in humans.

GRADAUS, R., et al.: Effect of Ventricular Fibrillation Duration on the Defibrillation Threshold in Humans. Early during ventricular fibrillation, the defibrillation threshold may be low, as ventricular fibrillation most probably arises from a localized area with only a few wavefronts and the effects of global ischemia, ventricular dilatation, and sympathetic discharge have not yet fully developed. The purpose of this study was to explore the effect of the timing of shock delivery in humans. During implantation of an ICD in 26 patients (24 men, 60 ± 11 years, 19 coronary artery disease, NYHA 2.2 ± 0.4, left ventricular ejection fraction 0.42 ± 0.16), the defibrillation threshold was determined after approximately 10 and 2 seconds of ventricular fibrillation. Ventricular fibrillation was induced by T wave shocks. Mean defibrillation threshold was 9.9 ± 3.6 J after 10.3 ± 1.0 seconds. Within 2 seconds, 20 of 26 patients could be successfully defibrillated with ≤ 8 J. In these patients, the mean defibrillation threshold was 4.0 ± 2.1 J after 1.4 ± 0.3 seconds compared to 9.5 ± 3.1 J after 10.2 ± 1.1 seconds (P < 0.001). There were no clinical differences between patients who could be successfully defibrillated within 2 seconds and those patients without successful defibrillation within 2 seconds. In the majority of patients, the defibrillation threshold was significantly lower within the first few cycles of ventricular fibrillation than after 10 seconds of ventricular fibrillation. These results should lead to exploration of earlier shock delivery in implantable devices. This could possibly reduce the incidence of syncope in patients with rapid ventricular tachyarrhythmias and ICDs.

Are patients with Werlhof's disease at increased risk for bleeding complications when undergoing cardiac surgery?

BACKGROUND It is generally assumed, that patients with Werlhofs disease (WD) are at increased risk for bleeding complications when undergoing cardiac surgery with extracorporeal circulation. Therefore we performed this case control study to estimate the real risk for bleeding complications of these patients. METHODS Between 05/95 and 07/98, ten patients with WD (eight males, two females) underwent cardiac surgery employing extracorporeal circulation (WD-group). Five of these patients with platelet counts below 80/nl were treated by immunoglobulins preoperatively. Each patient with WD was matched to five patients without WD (no-WD-group) using diagnosis, age, gender, ejection fraction, number of distal anastomosis and body-mass-index as matching criteria. RESULTS Mean number of platelet counts were significant lower in the WD-group than in the no-WD-group despite a significant increase of platelet counts after immunoglobulin treatment (54/nl-->112/nl, P=0.018). On the day before, directly after and on the first day after surgery they were 141/nl vs. 215/nl (P=0.012), 75/nl vs. 147/nl (P=0.001) and 93/nl vs. 136/nl (P=0.009). Accordingly, patients of the WD-group received significantly more platelet concentrates than patients of the no-WD-group (mean number of platelet concentrates: 2.3 versus 0.7, P=0.007). Total drainage loss via the mediastinal chest tubes was almost identical (1197 ml in the no-WD-group and 1140 ml in the WD-group). One patient of each group suffered from a bleeding complication requiring reexploration. Three patients of the no-WD-group (6%) and one patient of the WD-group (10%) expired postoperatively unrelated to WD. CONCLUSIONS Patients with WD may possibly undergo cardiac surgery without a markedly enhanced risk for bleeding complications despite a more than usual transfusion requirement and significantly lower platelet counts perioperatively.

Surgery of the inferior vena cava for tumor-related obstruction

Kidney tumors and pheochromocytomas of the adrenal gland may extend into the inferior vena cava (IVC) or even the right atrium. In these cases, curative surgery frequently requires partial resection of the IVC. From 1992 to 1995, 8 patients (6 kidney tumors, 2 pheochromocytomas of the adrenal gland) underwent tumor surgery with concomitant IVC resection. Four patients had tumor growth into the right atrium. Surgery was carried out during hypothermic circulatory arrest (n=4) using veno-venous bypass from the IVC to the jugular vein (n=2), or by simply clamping the IVC (n=2). In 6 patients the IVC was reconstructed using a PTFE prosthesis (n=2) or patch (n=4), in 2 patients the IVC was closed by a running suture only. All patients were discharged home 10–23 days after surgery (mean 13 days). During the follow-up (mean 23 months), 6 patients were in good clinical condition and without evidence of tumor recurrence up to 44 months after surgery and 2 patients died of metastases (16 and 17 months). Refinements of surgical techniques combined with a multidisciplinary approach involving vascular surgeons, cardiac surgeons, and urologists allow successful treatment of advanced tumor stages with IVC involvement, formerly considered a contraindication for surgery. The aggressive surgical approach is warranted not only for relief of symptoms, and acceptable survival rates can be achieved; even cure of the disease is possible.

Gastrointestinal Complications After Cardiopulmonary Bypass

Abdominal complications after extracorporeal circulation occur in 0.3%–2.3% of patients [1–14]. They carry significant mortality, up to 67% in some reports [1].