Successful extended lung preservation with UW solution.

Maximum preservation times of 4-6 hr continue to plague lung transplantation. The high-potassium colloid University of Wisconsin solution (UWS) has proved superior to the crystalloid modified Eurocollins' solution (ECS) for preservation of the liver, kidney, and pancreas. The purpose of this study was to compare UWS and ECS for extended lung preservation using a technique of combined pulmonary and bronchial artery perfusion. Simultaneous pulmonary artery and bronchial artery (via a closed aortic segment) perfusion was employed to harvest the lungs of ten mongrel dogs (wt 25-35 kg) using either UWS (n = 5) or ECS (n = 5) preservation solutions. Following 17 hr of cold (4 degrees C) pulmoplegic storage, the lungs were placed in an isolated perfused working lung (IPWL) apparatus. Seven freshly harvested lungs served as a control group (CON). Lung aerodynamics and gas exchange were evaluated at standard intervals until failure of the lung on the IPWL apparatus. Time until failure (mean +/- SEM) for each group was: CON = 209 +/- 14 min; UWS = 227 +/- 26 min; and ECS = 123 +/- 29 min. Only one of the ECS lungs lasted longer than 90 min. UWS-preserved lungs displayed a gas exchange efficiency equal to the CON group and better than that in the ECS-preserved lungs (lower A-aDO2, lower intrapulmonary shunt), suggesting better protection of the alveolar capillary membrane. Although the UWS lungs were initially less compliant than the ECS lungs, at no time was there a significant difference in the total work of respiration between the two groups. We conclude that UWS provides superior protection of the alveolar capillary membrane. The aerodynamic disadvantages of UWS preservation did not effect lung survival or total work of respiration.

Short-term and long-term results of experimental wrapping techniques for bronchial anastomosis.

Major complications of bronchial anastomoses for either transplantation or sleeve resection include early leak, fistula formation, granulation tissue, and stenosis. To evaluate the impact of technique on these complications, we designed a nonimmunocompromised canine model with a totally ischemic bronchial segment. We wished to discover the prevalence of early and late complications of a telescoping anastomosis and if wrapping techniques modify them. We autotransplanted 25 mm of left main-stem bronchus by telescoping 1 mm of proximal into distal bronchus sutured with interrupted 4-0 polyglactin sutures. The animals were divided into four groups: no wrap; omental pedicle wrap; detached-free omental wrap; and Gelfoam sponge soaked in porcine omental extract. Weekly bronchoscopic studies assessed airway patency. After the animals were put to death at 70 days, the luminal areas of the proximal anastomoses were compared with the origin of the left main bronchus. No air leak, bronchial disruption, or infection occurred in any group at any time. Luminal narrowing occurred in all four groups but was most pronounced in the three groups in which wrapping techniques were used. We conclude that wrapping of a telescoped anastomosis is not necessary to prevent early complications. However, no method completely eliminates stenosis. Further experiments should determine the effects of immunomodulation in this model.

Plasma renin activity in renal transplant patients with hypertension.

Chronic renal allograft rejection (CR) is the major cause of graft loss after 1 year following transplantation. Hypertension (HTN) and proteinuria (Up) are the hallmarks of this immunologic allograft response. Over 1 year, 23 patients posttransplantation and with HTN (diastolic greater than 95 mm Hg) were examined. Serial serum creatinine (Scr), Up, urine creatinine (Ucr), and resting and enalapril challenged (EC) plasma renin activity (PRA) were all determined. Renal artery stenosis was excluded by noninvasive imaging. Of the 23 patients, eight eventually lost their renal allografts, while 15 maintained satisfactory renal function (Scr less than 2.5). Results of this study show that: 1) worsening renal function (RF) increases EC reactivity; 2) the presence of proteinuria is not itself related to increase in EC activity; 3) renin before and after EC was higher (P = .06) in the allograft loss group. In this study, patients with high PRA represent the highest EC responses. Therefore, they display not macrovascular lesions, but microvascular intrarenal disease; this defect is most likely secondary to chronic immunologic insult.

Gastrointestinal tract complications after acute spine injury.

OBJECTIVES: To determine the incidence, risk factors, and mortality rate of gastrointestinal complications in patients with acute spine injury and to derive methods by which mortality can be reduced. DESIGN: Case series. SETTING: Regional tertiary care center. PATIENTS: Consecutive sample of 1952 patients with acute spine injury with complete medical records who were admitted from 1981 through 1990. MAIN OUTCOME MEASURES: Gastrointestinal tract complications, age, sex, time from injury to admission, cause of injury, level of spine injury, neurologic deficit, head injury, injury to other organ systems, incidence of surgical intervention for spine injury, length of hospital stay, and mortality rate. RESULTS: The incidence of gastrointestinal complications was 1.9%. Gastrointestinal hemorrhage was the most frequent complication. Risk factors for gastrointestinal complications were increasing age (P < .02), male sex (P < .01), injury to other organ systems (P < .02), head injury (P < .02), cervical spine injury (P < .02), and neurologic deficit (P < .005). The mortality rate was 19% in patients with gastrointestinal complications, significantly greater (P < .005) than the 2.9% rate in patients without gastrointestinal complications. CONCLUSIONS: Gastrointestinal complications after acute spine injury are uncommon but frequently lethal. Prophylaxis against hemorrhage and earlier diagnosis and surgical intervention are recommended.

Optimal pleurodesis: a comparison study.

With the resurgence of thoracoscopy, there is renewed interest in less invasive methods of pleurodesis. We wished to compare in an animal model a variety of methods suggested in reports. The purpose of the study was to rank the effectiveness of each procedure against the standard mechanical pleurodesis. Twenty-five mongrel dogs (weight, 25 to 35 kg) underwent bilateral thoracotomy. Each animal was randomly assigned to receive two of the following methods of pleurodesis: tetracycline, talc, mechanical abrasion, neodymium: yttrium-aluminum garnet (Nd:YAG) laser (Hereus Inc, E. Rutherford, NJ) photocoagulation, and argon beam coagulator (ABC) (Beacon Lab, Bloomfield, CO) electrocoagulation of the parietal pleura. At evaluation at 30 +/- 2 days, the efficacy of pleurodesis was graded on a scale of 0 to 4, with 0 representing a complete absence of pleural symphysis and 4 the adhesion of more than one lobe to both the chest wall and mediastinum. Mean grade and standard deviation of each method were: talc, 3.0 +/- 0.67; mechanical, 3.0 +/- 0.82; tetracycline, 2.3 +/- 1.4; ABC, 1.5 +/- 0.97; and Nd:YAG laser, 0.7 +/- 0.95. Both the talc and mechanical methods were superior to either the Nd:YAG laser or the ABC (p < 0.01). In this study, neither the Nd:YAG laser nor the ABC proved efficacious in producing pleurodesis. Talc poudrage is the only method of pleural symphysis comparable with mechanical abrasion.

Computed tomography in the initial evaluation of patients with blunt trauma.

Two hundred sixty-six of 374 consecutive blunt trauma patients underwent emergency computed tomographic (CT) scanning during evaluation at a level I trauma center. The purpose of this study was to develop guidelines for use of CT scanning in the initial evaluation of blunt trauma patients. Of the 131 CT scans of the head obtained, 20 (15%) had positive results. Seven patients whose initial neurologic examinations were normal had abnormal results on head CT scans; none required emergent treatment of their head injury. This suggests that, in the presence of a normal neurologic examination, head CT scans can safely be delayed until other more serious injuries are addressed. Twenty-six CT scans of the chest were performed and ten (38%) were interpreted as abnormal. Chest CT scans provided information about the extent of the injury but did not alter the initial management of any patient and therefore are rarely indicated in the acute evaluation of trauma patients. A total of 110 abdominopelvic CT scans were performed and 20 (19%) were interpreted as positive. Seventy-five percent of those patients with positive CT scans were treated successfully in a nonsurgical fashion.

In vivo assessment of nonlinear myocardial deformation using finite element analysis and three-dimensional echocardiographic reconstruction.

In vitro data have shown that the myocardium exhibits nonlinear passive stress-strain relationship and a non-linear pressure-volume relationship. A finite element (FE) analysis and optimization algorithm was used on three-dimensional reconstructed left ventricular (LV) geometry using echocardiographic images, along with hemodynamic measurements, in seven closed-chest dogs to show a nonlinear stress-strain relationship in vivo. Our analysis included the computation of Poisson's ratio from the measured volumetric strain of the myocardium and a simulated pericardial pressure load ("equivalent pericardial pressure") applied to the epicardial surface of the reconstructed LV. LV geometry was reconstructed in three or four incremental time steps in diastasis and the myocardium was assumed to be homogeneous, isotropic, and linearly elastic during these short intervals in this initial study. Simultaneous LV chamber pressure and equivalent pericardial pressure were incorporated into the algorithm to predict actual LV expansion. Computations were performed iteratively at each interval to compute the optimized elastic modulus. By performing the FE analysis and optimization at each interval (a step-wise linear analysis approach), a linear relationship between the myocardial elastic modulus and LV chamber pressure was derived (r = .87 to .98). Such a linear relationship is equivalent to an exponential myocardial stress-strain relationship in vivo. Detailed measurement of nonhomogeneous regional deformation are becoming possible with the advent of sophisticated imaging techniques. The methodology described in this study, with appropriate modifications in the FE analysis and optimization algorithms, can be applied to assess the complex three-dimensional pressure-deformation characteristics in vivo.

Mesenteric artery bypass: objective patency determination.

PURPOSE: Many authors have reported extended relief of intestinal ischemia by use of a variety of reconstructive techniques, but all have relied on symptomatic follow-up. None have objectively measured patency rates. The purpose of this study was to determine the primary patency rates of bypass grafts placed for acute and chronic splanchnic atherosclerotic occlusive disease with use of objective follow-up with mesenteric duplex ultrasound scanning or arteriography. METHODS: Twenty-five consecutive patients (mean age 61, female/male ratio of 2.7:1) who underwent placement of 38 splanchnic bypass grafts (29 saphenous vein grafts, 9 polytetrafluoroethylene) (22 retrograde, 16 antegrade) for ischemic symptoms (9 acute ischemia: 16 chronic ischemia) between 1984 and 1994 were monitored with either duplex scanning (30 grafts) or arteriography. Life-table and log rank analysis were used to determine and compare graft patency. RESULTS: Three patients (12%, 2 acute ischemia and 1 chronic ischemia) died after operation. Six patients (30%) had significant morbidity (4 acute ischemia and 2 chronic ischemia). During follow-up from 1 to 136 months (mean 35 months), no patient died of bowel infarction or required revision for recurrent symptoms. Objective testing revealed three graft occlusions. Symptomatic follow-up had a sensitivity of only 33% for graft occlusion when compared with objective measurement. The life-table primary patency rate was 89% at 72 months. Life-table survival for the same patients was 75% at 36 months. Patency rates for antegrade (93% at 36 months) versus retrograde (95% at 36 months) bypass and saphenous vein grafts (95% at 36 months) versus polytetrafluoroethylene (89% at 36 months) were not significantly different (p = 0.47 and 0.43, respectively). Late patency rates of grafts placed for acute ischemia (92% at 36 months) versus chronic ischemia (89% at 36 months) were not significantly different (p = 0.77). CONCLUSION: Splanchnic bypass for mesenteric ischemia, with a primary patency rate of 89% at 72 months, is an extremely durable form of revascularization. Long-term patency of grafts placed for acute ischemia does not differ significantly from that of bypasses for chronic occlusion. Duplex scanning allows standardized objective periodic follow-up of splanchnic reconstruction. Objective assessment is critical to accurately measure visceral revascularization patency rates.