Richard K. Spence

Inelastic versus elastic leg compression in chronic venous insufficiency: a comparison of limb size and venous hemodynamics.

PURPOSEnCompression of the lower extremity is the mainstay of therapy in patients who have chronic venous insufficiency. We evaluated the ability of two forms of compression-elastic stockings and an inelastic compression garment-with air plethysmography to determine how well they corrected abnormal deep venous hemodynamics in patients who had class III chronic venous insufficiency and how well this correction was sustained over time.nnnMETHODSnPatients had measurements taken with no compression, with a 30 to 40 mm Hg below-knee stocking, and with the inelastic compression garment 2 hours and 6 hours after donning the garments. Therapies were compared with baseline and with themselves over time.nnnRESULTSnInelastic compression maintained limb size and reduced venous volume better than no compression or stockings over time (ankle circumference at 2 hr vs 6 hr: baseline, 24.7 +/- 7 cm vs 26.1 +/- 1.1 cm; stocking, 23.9 +/- 1.1 cm vs 26.2 +/- 1.2 cm; inelastic compression, 25.4 +/- 1.1 cm vs 25.4 +/- 0.9 cm; venous volume at 2 hr vs 6 hr: baseline, 97.5 +/- 14.1 ml vs 105.2 +/- 17.9 ml; stocking, 112.4 +/- 29.7 ml vs 77.5 +/- 13.2 ml; inelastic compression, 72.2 +/- 14.1 ml vs 56.1 +/- 10.2 ml). At 6 hours, the ejection fraction was increased and the venous filling index was significantly less with inelastic compression compared with the stocking and baseline (ejection fraction at 6 hr: baseline, 61.6% +/- 6.9%; stocking, 75.9% +/- 17.7%; inelastic compression, 78.8% +/- 12.2%).nnnCONCLUSIONSnInelastic compression has a significant effect on deep venous hemodynamics by decreasing venous reflux and improving calf muscle pump function when compared with compression stockings, which may exert their primary effect on the superficial venous system.

Transfusion guidelines for cardiovascular surgery: Lessons learned from operations in Jehovah's Witnesses

Patients undergoing cardiovascular surgery are among the top users of homologous blood transfusion (HBT). Awareness of the risks of disease transmission and immune system modulation from HBT has prompted us to find alternatives such as autologous predonation (APD) and intraoperative autotransfusion (IAT). However, these latter options are not appropriate for all patients. We reviewed our experience with 59 Jehovahs Witness patients who underwent 63 elective cardiovascular procedures without either HBT or APD to determine the safety of operation without these modalities and to develop revised maximum surgical blood-ordering schedule guidelines for cardiovascular surgery. Estimated blood loss averaged 870 ml, but one third to one half of losses were replaced by IAT. IAT was not needed in lower extremity bypass operations in which the estimated blood loss was less than 150 ml. Three of 59 patients died (5.1%), but only one died of operative bleeding complications. We conclude that (1) elective cardiovascular operations can be done safely without the use of either HBT or APD, (2) HBT is not necessary in leg bypass procedures, and (3) maximum surgical blood-ordering schedule guidelines for HBT in major cardiovascular operations can be reduced to near zero by the use of intraoperative autotransfusion and acceptance of a postoperative hemoglobin nadir of 7.0 gm/dl.

Transfusion and surgery

In this survey of transfusion in surgery, we have attempted to provide the surgeon with an understanding of the problems associated with homologous transfusion and a practical knowledge of treatment strategies and alternatives designed to reduce homologous blood exposure. Such a review cannot be encyclopedic. Our hope is that it will serve the reader as a stimulus to examine his or her transfusion practices and as a guide for future self-learning.

Aortocaval fistula treated by aortic exclusion

Aortocaval fistulas are a rare complication of spontaneous rupture of an abdominal aortic aneurysm, representing an incidence of 2% and 4%. A review of the literature revealed 159 reported cases of aortocaval fistulas. We recently had a patient admitted to our institution with an abdominal aortic aneurysm that ruptured into the vena cava. The presence of the fistula was only recognized during operation. Primary closure of the fistula was not possible, and the aneurysmal segment was excluded. To our knowledge, this is the first report of aortic exclusion being used as the surgical treatment of an aortocaval fistula.

Perfluorocarbons in the Twenty-First Century: Clinical Applications as Transfusion Alternatives

The risks of allogeneic transfusion are well known to physicians and have prompted a search for alternatives. Perfluorocarbons were introduced into clinical trials in the early 1980s with the hope that these products would develop into acceptable blood substitutes. Unfortunately, the limited potency, short half-life, and potential toxicity of these early formulations coupled with unrealistic expectations for efficacy prevented the perfluorocarbons from playing a significant role in transfusion medicine. Recent changes in formulation to improve efficacy and eliminate toxicity have stimulated renewed interest in perfluorocarbons as alternatives to allogeneic transfusion. Our recent work has focused on the role of perfluoroctylbromide (PFOB), a second generation perfluorocarbon, as an adjunct to autologous transfusion and acute normovolemic hemodilution (ANH), rather than as a total blood substitute. Initial animal experiments have shown the ability of small doses of PFOB to maintain oxygen delivery without the need for blood transfusion in the setting of hemodilution. Our presentation will focus on subsequent clinical work using PFOB as an alternative to both allogeneic and autologous blood transfusion during ANH. We believe that perfluorocarbons such as PFOB will have a significant role in the future as one of several, additive alternatives to blood transfusion.

Comparison of costs and healing rates of two forms of compression in treating venous ulcers

The objective of this study was to compare healing rates and costs of treating venous ulcers with traditional Unna boots (UB) or a CircAid Thera-Boot (TB). A multicenter, prospective, randomized parallel-group study was performed in three university medical center vascular surgery clinics and three private medical offices. Patients presented with unilateral venous leg ulcers 5 cm or less in diameter. Patients with severe arterial, metabolic, or neuropathic diseases, and those who would not be expected to heal with conservative treatment, were excluded. Conservative treatment of the leg ulcer consisted of a nonadherent topical dressing and compression with either a traditional Unnas boot or a Thera-Boot. The main outcome measures were the following: time to healing, rate of area decrease, rate of percent area decrease, linear healing rate, costs of labor, materials, and overhead. Of 38 enrolled patients seven were withdrawn (five UB, two TB). Three patients were still in treatment when the study was stopped. Eleven UB patients and 17 TB patients completed the study. Healing rates were for UB and TB patients (mean (Meeting ± sd) were, respectively: time to healing (weeks) 9.69 ± 3.28, 7.98 ± 4.41 (p = 0.41), area healing rate (cm2/day) 0.0239 ± 0.0534, 0.0433 ± 0.0910 (p = 0.27),% area healing rate (%/day) 1.0493 ± 1.5583, 2.0357 ± 1.9520 (p = 0.56), and linear healing rate (cm/day), 0.0060 ± 0.0092, 0.0109 ± 0.0125 (p = 0.27). Costs for UB and TB (dollars to completion) were, respectively: clinician labor 331.37 ± 255.75, 201.91 ± 131.17 (p = 0.09), materials 160.86 ± 96.86, 122.79 ±27.59 (p= 0.14), overhead (number of visits) 11.70 ± 6.40, 6.71 ±3.77 (p = 0.02), and total costs 901.73 ± 576.45, 559.41 ±290.75 (p= 0.05). Treatment of venous ulcers with Circ Aid Thera-Boots is significantly less costly than treatment with traditional Unnas boots. Trends toward faster healing were noted.

Perfluorocarbons as blood substitutes: the early years. Experience with Fluosol DA-20% in the 1980s.

Clinical testing of perfluorocarbons (PFC) as blood substitutes began in the early 1980s in the form of Fluosol DA-20% (FDA), a mixture of perfluorodecalin and perfluorotripropylamine emulsified with Pluronic F68. We have treated 55 patients (Treatment (T) = 40; Control (C) = 15) with intravenous infusions of 30 cc/kg of FDA as part of either a randomized, clinical trial or a humanitarian protocol. All patients were Jehovahs Witnesses who refused blood transfusion and were severely anemic (mean hemoglobin = 4.6 g/d). FDA successfully increased dissolved or plasma oxygen content (P1O2 in ml/dl), but not overall oxygen content (T group: P1O2 baseline = 1.01 +/- .27, P1O2 12hrs = 1.58 +/- .47 [p = < .0001, t-test]; P1O2 12 hrs: T = 1.58 +/- .47, C = 1.00 +/- .31, p = < .0002, t-test). This effect persisted for only 12 hours post infusion, and had no apparent effect on survival. FDA is an ineffective blood substitute because of low concentration and short half-life. Improved emulsion design may resolve these problems, thereby producing a more effective agent. Our discussion will include a review of our data plus a summary of other reports of FDA efficacy as a blood substitute.

Preoperatively assessing and planning blood use for elective vascular surgery.

Few guidelines exist for determining transfusion needs and strategies, namely, the appropriate use of autologous versus homologous blood for elective vascular surgery. To address this deficiency, we have developed and used an algorithm based on an analysis of the procedure, maximum surgical blood ordering schedule, patient status, and patient suitability for autologous alternatives. Data were derived from consecutive major vascular procedures done at our hospital from 1991 to 1992. The algorithm helps the surgeon assess transfusion need and patient suitability for autologous predonation and aids in selecting appropriate transfusion alternatives. Using this algorithm during the past year with 120 patients, we simplified transfusion decisions, reduced homologous blood use (to only 4.2%), and reduced wasting of autologous blood to less than 5% of the units predonated. We believe that the use of this algorithm will aid the vascular surgeon in choosing appropriate alternatives to allogeneic blood transfusion, thereby reducing the patients exposure to risk. The algorithm should also reduce wasting of autologous blood.

Hemorrhoidectomy in the patient with multiple or circumferential hemorrhoids.

A technique is presented that allows complete removal of hemorrhoids even when large hemorrhoids exist between the classic three major hemorrhoidal location. Since the anorectal mucosa overlying these “interval” hemorrhoids is preserved, there is no increased tendency for stricture formation to occur.

Improvement in Circulatory and Oxygenation Status by Perflubron Emulsion (Oxygent™ HT) in a Canine Model of Surgical Hemodilution

To examine the effect of a low dose of Oxygent HT on hemodynamics and oxygen transport variables in a canine model of profound surgical hemodilution, two groups of adult anesthetized splenectomized beagles were hemodiluted with Ringers solution to Hb 7 g/dL. The treated group received 1 mL/kg Oxygent HT (90% w/v perflubron emulsion [perfluorooctyl bromide], Alliance Pharmaceutical Corp.) and both groups (7 controls and 10 treated) were further hemodiluted using 6% hydroxyethyl starch until cardiorespiratory decompensation occurred. Pulmonary artery catheterization data and oxygen transport variables were recorded at Hb decrements of 1 g/dL breathing room air. There was no difference among groups during initial hemodilution. However, in the Oxygent HT group there was a statistically significant improvement in mean arterial pressure, CVP, cardiac output, PvO2, SvO2, DO2, and pulmonary venous admixture shunt during profound hemodilution to Hb levels of 6, 5, and 4 g/dL. A low dose of Oxygent HT offered benefit in improving hemodynamics and oxygen transport parameters even under air breathing conditions in a model of surgical hemodilution. This effect was most apparent at lower levels of Hb.