Thomas C. Naslund

Risk of spinal cord dysfunction in patientsundergoing thoracoabdominal aortic replacement

The records of 150 consecutive patients underoingthoracoabdominal aortic replacement from 1980 to 1991 were retrospectively reviewed. There were 89 men and 61 women; mean age was 67.8 years (range: 33 to 88 years). Since June 1989, a multimodality prospective perioperative protocol was used to reduce the risk of spinal cord dysfunction. Ischemia is minimized by complete intercostal reimplantation whenever possible, cerebrospinal fluid drainage, and maintenance of proximal hypertension during cross-clamping. Spinal cord metabolism is reduced by moderate hypothermia, high-dose barbiturates, and avoidance of hyperglycemia. Reperfusion injury is minimized by the use of mannitol, steroids, and calcium channel blockers. Ninety-seven percent of patients survived long enough for evaluation of their neurologic function. Spinal cord dysfunction was reduced from 6 of 108 (6%) in the preprotocol group to 0 of 42 in the protocol group (0%) (p A multimodality protocol appears to be effective in reducing the risk of spinal cord injury during thoracoabdominal aortic replacement.

The reduction of the allogenic transfusion requirement in aortic surgery with a hemoglobin-based solution******

OBJECTIVE Because of allogenic red blood cell (RBC) availability and infection problems, novel alternatives, including hemoglobin-based oxygen-carrying solutions (HBOC), are being explored to minimize the perioperative requirement of RBC transfusions. This study evaluated HBOC-201, a room-temperature stable, polymerized, bovine-HBOC, as a substitute for allogenic RBC transfusion in patients undergoing elective infrarenal aortic operations. METHODS In a single blind, multicenter trial, 72 patients were prospectively randomized two-to-one to HBOC (n = 48) or allogenic RBC (n = 24) at the time of the first transfusion decision, either during or after elective infrarenal aortic reconstruction. Patients randomized to the HBOC group received 60 g of HBOC for the initial transfusion and had the option to receive three more doses (30 g each) within 96 hours. In this group, any further blood requirement was met with allogenic RBCs. Patients randomized to the allogenic RBC group received only standard RBC transfusions. The efficacy analysis was a means of assessing the ability of HBOC to eliminate the requirement for any allogenic RBC transfusions from the time of randomization through 28 days. Safety was evaluated by means of standard clinical trial methods. RESULTS The two treatment groups were comparable for all baseline characteristics. Although all patients in the allogenic RBC group required at least one allogenic RBC transfusion, 13 of 48 patients (27%; 95% CI, 15% to 42%) in the HBOC group did not require any allogenic RBC transfusions. The only significant changes documented were a 15% increase in mean arterial pressure and a three-fold peak increase in serum urea nitrogen concentration after HBOC. The complications were similar in both groups, with no allergic reactions. There were two perioperative deaths (8%) in the allogenic RBC group and three perioperative deaths (6%) in the HBOC group (P = 1.0). CONCLUSION HBOC significantly eliminated the need for any allogenic RBC transfusion in 27% of patients undergoing infrarenal aortic reconstruction, but did not reduce the median allogenic RBC requirement. HBOC transfusion was well tolerated and did not influence morbidity or mortality rates.

Cost-effective method for bedside insertion of vena caval filters in trauma patients

BACKGROUND The need for patient transport for inferior vena cava (IVC) filter placement impacts patient safety, comfort, charges, and nursing care. Bedside, ultrasound-guided IVC filter placement may offer an acceptable, cost-effective alternative. METHODS Prospective cohort study of 55 consecutive trauma patients requiring IVC filter placement. During a 13-month period (August of 1995-September of 1996), patients meeting criteria for IVC filter were evaluated. Complications were recorded, and the potential financial savings were determined. RESULTS Of 3,172 trauma admissions, 55 patients met IVC filter criteria and 49 patients had IVC filters placed under ultrasound guidance. In six patients (10.9%), ultrasound guided filter placement failed. There were four complications in four patients (8.2%). Over 13 months, charges were reduced by

Technical complications of endovascular abdominal aortic aneurysm repair

69,800 when compared with radiology suite placement and

Low sodium intake corrects abnormality in β‐receptor–mediated arterial vasodilation in patients with hypertension: Correlation with β‐receptor function in vitro

118,300 when compared with operative placement. CONCLUSIONS Ultrasound guided, bedside placement of IVC filters is a safe, cost-effective method of pulmonary embolism prophylaxis in select trauma patients.

Endoleak Following Endovascular Abdominal Aortic Aneurysm Repair: Implications for Duration of Screening

PURPOSE Results from 34 endovascular repairs of abdominal aortic aneurysms are reviewed to identify technical complications and relate them to anatomic and technical features of the operation. METHODS Twenty-one patients underwent attempted tube graft repair (mean follow-up, 13 months). Thirteen patients underwent placement of a bifurcated graft (mean follow-up, 7.2 months). RESULTS Twenty-five patients (74%) underwent repair without technical complication (16 tube graft and nine bifurcated graft). Of five patients who had tube graft complications, two involved small iliac arteries and resulted in arterial injury. One of these patients needed a femorofemoral bypass procedure, and the other required conversion to standard operation. Two patients had distal leaks associated with the attachment system, and one patient had misplacement of the distal attachment system. The two patients who had leaks were followed-up; one required operation after 7 months, whereas the other leak sealed. The patient who had distal attachment system misplacement had a second endograft placed within the first to provide a distal seal. The four patients who had bifurcated graft complications involved two graft limb stenoses, one managed with a Palmaz stent and the other with balloon angioplasty. The patient treated with balloon angioplasty had graft thrombosis 1 week after the operation, which resulted in the need for a femorofemoral bypass procedure. Another bifurcated graft patient had a graft limb twist, which has resulted in chronic claudication. One patient had placement of a limb too proximal in the common iliac artery with chronic leak, and an open operation was performed 18 months later. CONCLUSIONS Technical complications in this series seem to be associated with short distal necks, small iliac arteries, tortuous iliac arteries, and atherosclerosis at the aortic bifurcation. We believe that experience and understanding of these issues will reduce the risk of these complications in the future.

Prospective randomized multicenter trial of fibrin sealant versus thrombin-soaked gelatin sponge for suture- or needle-hole bleeding from polytetrafluoroethylene femoral artery grafts

To determine the contribution of altered β‐receptor function in the vasculature to the increased peripheral vascular resistance seen in hypertension, the effects of intra‐arterial infusions of isoproterenol and epinephrine on forearm blood flow were determined in 11 male normotensive subjects and 11 male hypertensive subjects during 10 and 250 mmol/day sodium diets. Increased sodium intake from 10 to 250 mmol produced contrasting effects in the hypertensive and normotensive subjects. In the hypertensive subjects, sensitivity to isoproterenol decreased when sodium intake increased (median effective dose increased from 39 [95% confidence limits, 30 to 50] to 70 [95% confidence limits, 42 to 116] ng/min, p < 0.05). On the other hand, in the normotensive subjects increased sodium intake resulted in an increased sensitivity to isoproterenol induced vasodilation (median effective dose decreased from 52 [38 to 71] to 29 [22 to 38] ng/min, p < 0.01). No change occurred in sensitivity to epinephrine or in the maximum vasodilatory response to ischemia during dietary changes. Changes in β‐receptors on lymphocyte membranes paralleled the changes seen in vascular sensitivity so that the proportion of receptors exhibiting high affinity for agonists, a reflection of receptor adenylate cyclase coupling, decreased in the hypertensive subjects from 38.0% ± 3.8% when they were receiving 10 mmol/day sodium to 29.6% ± 2.7% when they were receiving 250 mmol/day sodium (p < 0.01). However, the proportion increased from 32.4% ± 3.7% for normotensive subjects receiving 10 mmol/day sodium to 47.1% ± 7.8% for normotensive subjects receiving 250 mmol/day sodium (p < 0.05). There was a significant correlation between sensitivity to β‐receptor–mediated vasodilation in the vasculature and measures of β‐receptor sensitivity on human leukocyte membranes. We conclude that increased sodium intake is associated with increased sensitivity to β‐receptor–mediated vasodilation in normotensive subjects but not in hypertensive subjects who appear to lack this facility to compensate for volume expansion.

Endovascular grafting of abdominal aortic aneurysms. A preliminary study.

Objective:Endovascular abdominal aortic aneurysm repair (EAR) requires long-term surveillance for endoleak or increase in aneurysm diameter. We analyzed the natural history of and risk factors for endoleak development. Summary Background Data:Endoleak is a common complication of EAR that can lead to aneurysm enlargement and even rupture. Following EAR, imaging studies are used to identify leaks since patients with endoleak may require additional endovascular interventions or conversion to open repair. No criteria currently exist for cessation or reduction in frequency of screening imaging studies. Methods:Data on 220 patients undergoing EAR were retrospectively reviewed. Kaplan-Meier survival analysis and Cox proportional hazards regression were used with the end point being new endoleak development. Potential risk factors included preoperative aneurysm diameter, number of negative surveillance studies, and postoperative increase in diameter. Results:A total of 52 patients (24%) who underwent EAR had endoleak detected during postoperative follow-up, which averaged 19 months (range, 0.4–101 months). One, 6-, 12-, and 24- month endoleak-free survival was 90%, 80%, 77%, and 73%, respectively. Three leaks occurred after year 2, at postoperative months 24, 48, and 85. Increasing number of negative screening studies was negatively associated with risk for endoleak development (B = −3.122, P < 0.001), while increase in aneurysm diameter was positively associated with risk for endoleak (B = 0.072, P = 0.04). Conclusion:Risk for endoleak declines as the number of negative postoperative scans increases, but new endoleaks are identified as late as 7 years following EAR. Reduction in screening frequency cannot be uniformly recommended at this time. Patients with documented aneurysm expansion should be monitored carefully and endoleak should be suspected.

Natural history of grade I-II blunt traumatic aortic injury.

OBJECTIVE We evaluated the safety and efficacy of the fibrin sealant Beriplast P (FSBP; Aventis-Behring) for hemostasis in anastomosis of polytetrafluoroethylene (PTFE) grafts to the femoral artery. METHODS In a single-blinded randomized prospective multicenter clinical trial, FSBP was compared with thrombin-soaked gelatin sponge (TSG) for efficacy in stopping bleeding from needle or suture holes in PTFE grafts after anastomosis to the femoral artery. Patients were randomized to FSBP application, which requires a 3-minute period of arterial clamping to enable the fibrin clot to adhere, or to TSG application, which requires pressure from gauze sponges, after completion of the femoral artery anastomosis. The primary end point was hemostasis, defined as absence of any detectable bleeding as judged by the operating surgeon, by 4 minutes after randomization. Secondary end points included actual time from randomization to hemostasis, time to beginning of wound closure, measured blood loss (weighed sponges), incidence of recurrent bleeding, stay in the intensive care unit, and hospital length of stay. Data were analyzed with the intention-to-treat method. RESULTS Two hundred thirty-five subjects were enrolled at 26 medical centers; 34 were subsequently excluded from the study. Of the 201 randomized subjects, 100 received FSBP and 99 received TSG. Hemostasis was achieved by 4 minutes in 64 subjects (63%) in the FSBP group and 40 subjects (40%) in the TSG group (P =.0018). In the FSBP group, compared with the TSG group, time to hemostasis was shorter (median, 4.0 minutes; 95% confidence interval [CI], 3.8-4.18 minutes vs median, 5.6 minutes, 95% CI, 4.5-7.0; P =.008), blood loss was less (mean, 4.0 +/- 29.7 g vs mean, 15.6 +/- 28.4 g; P <.0001), and time to wound closure was shorter (median, 15 minutes; 95% CI, 10.47-18.67 minutes vs median, 22.8 minutes; 95% CI, 18.67-30.67; P =.005). There were no differences in recurrent bleeding or any other adverse events. There was no significant difference in ICU stay, but hospital length of stay was shorter in the FSBP group compared with the TSG group, and the difference approached significance (median, 6.5 days; 95% CI, 5.00-7.00 days vs median, 7.0 days; 95% CI,. 6.00-8.00 days; P =.0565). CONCLUSION FSBP is more effective than TSG for achieving hemostasis of needle or suture hole bleeding from PTFE femoral artery grafts.

Duplex-directed vena caval filter placement: Report of initial experience ☆

OBJECTIVE The authors report the experience of a single investigational center involving two Phase I and a Phase II clinical trials approved by the Food and Drug Administration (FDA) for the transfemoral implantation of woven Dacron grafts for abdominal aortic aneurysms. SUMMARY BACKGROUND DATA In 1993, EndoVascular Technologies, Inc. ([EVT]; Menlo Park, CA), began an FDA-approved clinical trial of repair of abdominal aortic aneurysms by transfemoral placement of a tube endograft. Subsequently, a bifurcated endograft trial was started. This the first single institution report using the EVT endograft for both tube and bifurcated aortic replacement. METHODS Seventeen patients were enrolled in two Phase I and one Phase II clinical trials. The Phase I tube graft trial and the Phase I bifurcated graft trial were nonrandomized studies. The Phase II tube graft trial consisted of a randomized prospective control trial of open endoaneurysmorrhaphy versus transfemoral placement of an endograft. RESULTS Seventeen patients were enrolled in the trial. The graft was placed successfully in all but one patient. Five patients randomized to open procedure and one declined to participate. Eleven patients with endografts are available for follow-up. One graft has been explanted for attachment system migration. One patient is a late failure because of persistent filling of the aneurysm sac. CONCLUSION Transfemoral placement of an endovascular graft is a viable and effective treatment of abdominal aortic aneurysms in the short term. Use of a bifurcated endograft will open the procedure to more patients. The ideal attachment system and graft material await long-term implantation follow-up.