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Biomedical subjects

R L Tawes

Publications and source records attributed to R L Tawes.

At least 19 recordsLinked to original sources
PubMed1996

Is the "salvaged-cell syndrome" myth or reality?

BACKGROUND: Intraoperative autotransfusion (IAT) has been implicated in anecdotal cases and experimental models to precipitate, aggravate, or exacerbate a coagulopathy. This study assesses this hypothesis. METHODS: A retrospective database review of over 36,000 multispecialty cases of IAT during an 18-year experience was conducted with special reference to the occurrence of coagulopathy (disseminated intravascular coagulation [DIC]) in association with adult respiratory syndrome (ARDS). RESULTS: The incidence of coagulopathy was low (0.05%). A total of 18 cases of DIC/ARDS were identified: 10 associated with ruptured aneurysms, 6 following massive trauma, and 2 after complex redo cardiac surgery. All 18 patients suffered shock and profound hypothermia. The mean transfusion requirement was 28 units. The mortality was 100%. CONCLUSION: Although some degree of bleeding and clotting disorders are not uncommon in major cases, in our experience coagulopathy occurs infrequently and is a result of a complex interaction of shock, hypothermia, and multiple transfusions. It is our contention that these factors trigger the DIC, not the autotransfusor, and that the ARDS results from reperfusion injury following a profound ischemic event, associated in many cases with multiorgan failure.

Blood Transfusion, Autologous↗
PubMed1996

Value of single photon emission computerized imaging in the treatment of patients undergoing carotid endarterectomy.

PURPOSE: The purpose of this study was to evaluate the clinical relevance of regional cerebral blood flow by single photon emission computerized imaging (SPECT) in patients undergoing carotid endarterectomy (CEA). METHOD: Eighty-four patients were included in this study; 74 were undergoing CEA. All 74 operative cases had SPECT scans before and after surgery. The first 30 patients undergoing CEA also had computed tomography scans for comparison. Findings were correlated during surgery with carotid stump pressures. RESULTS: No deaths and no strokes occurred. Four complications were seen. In the first 30 patients with computed tomography scans, 20 had positive SPECT scans, whereas the computed tomography scan was negative. A 100% linear correlation was seen with operative stump pressures, and decreased regional cerebral blood flow was noted on SPECT scan before surgery (48 abnormal with mean 26 mm). These patients received shunts during CEA. CONCLUSION: SPECT scans add useful physiologic data to anatomic images and provide factual or objective information that is valuable in treating patients undergoing CEA. A positive SPECT scan is predictive of poor collateral circulation and may possibly identify those "at risk," if they have no symptoms, and those who will require shunting during surgery. SPECT scans may facilitate case selection in severe bilateral carotid stenosis and deferment of operation in elderly patients at high risk. After surgery SPECT scans will document the value of successful CEA in reestablishing normal regional cerebral blood flow. Finally, SPECT scans have potential value for reevaluating patients who have complete carotid occlusion for external carotid/internal carotid artery bypass.

Acetazolamide↗
PubMed1996

Endoscopic technique for subfascial perforating vein interruption.

Surgical treatment of incompetent perforating veins of the lower leg performed openly carries considerable morbidity associated with wound healing. Newer minimally invasive techniques offer an effective treatment alternative that avoids the lengthy incisions of the classical subfascial ligation techniques. The authors report a simple and quick two-port endoscopic method for clipping incompetent perforating veins of the lower leg using commonly available endoscopic instrumentation. The technique is unique in its use of a balloon dissector to rapidly establish the subfascial working space.

Endoscopes↗
PubMed1994

Autologous fibrin glue: the last step in operative hemostasis.

BACKGROUND: Fibrin glue may be the perfect hemostatic agent for operative use as it seals in minutes, has no tissue toxicity, reabsorbs, and promotes local tissue growth and repair. Use in the United States has been limited because of lack of Food and Drug Administration approval of the commercial homologous products, lack of a concentrated source of fibrinogen, and because of the potential for viral transmission, particularly hepatitis, with pooled homologous plasma and cryoprecipitate-based methods. Autologous fibrin glue (AFG) obviates these problems. METHODS: During the past year, we obtained AFG through the same routine predonation procedure as with red blood cells before major elective surgery. Intraoperatively, we made AFG from the platelet-rich plasma derived from the Plasma-Saver. Our experience has been with 36 patients undergoing aortic, thoracoabdominal, and thoracic surgery, as well as patch graft angioplasty cases. RESULTS: Fibrin glue formation mimics the final stage in the coagulation cascade. The AFG from predonation acts more like an epoxy glue, while the AFG made during surgery is less viscous and acts more like a sealant because of the lesser concentration of fibrinogen in platelet-rich plasma. In emergencies, however, the intraoperative method is obviously the only choice available, and it is a useful adjunct to hemostasis at the end of the procedure. The technique will be described. CONCLUSION: This relatively new approach to hemostasis should gain popularity because it is easy and fairly inexpensive to produce, and because the patient's own blood is used.

Aneurysm↗
PubMed1994

Alternatives to homologous blood transfusion.

This article presented an overview of the available alternatives to homologous blood transfusion. Each of these alternatives will be examined in depth in subsequent articles of this issue. The recurrent themes of conservatism and recycling of one's own blood will be emphasized throughout the text by the various authors. Emerging technologies and techniques, and their potential influence on transfusion therapy will be evaluated.

Blood Donors↗
PubMed1994

The basic concepts of an autotransfusor: the Cell-Saver.

The basic concepts in the technology and techniques have been presented. Other articles in this issue discuss in more detail the physiological considerations of autotransfused RBCs as well as the efficiency of the Cell-Saver from the standpoint of a hematologic evaluation.

Blood Transfusion, Autologous↗
PubMed1994

Postoperative salvage: a technological advance in the 'washed' versus 'unwashed' blood controversy.

AT techniques are becoming the standard of care in surgery. Some controversy exists regarding the use of washed versus unwashed salvaged blood, as discussed. The literature concerning this unresolved problem has been reviewed. Because blood collected intraoperatively has undergone clotting and lysis, no beneficial coagulation effects can be expected with reinfusion of unwashed blood. If, additionally, potentially harmful effects may result, a strong argument can be made for washing the RBCs free of the activated clotting factors before reinfusion. Theoretically, this has strong appeal. In practice, it is recognized that patients who are in good health can tolerate small volume reinfusion of unwashed blood, particularly if they have been anticoagulated. In weighing the options and the risk/benefits equation, it would appear that washing the RBCs is generally the safest course. Now, it seems that there is a definite trend toward washing the red cells before reinfusion. Technological advances make this possible. The Haemolite 2 is a small, compact, portable autotransfusor that provides a safe, practical, and efficient means of recycling the patients own blood in the postoperative salvage setting.

Blood Transfusion, Autologous↗
PubMed1991

Vein patch rupture after carotid endarterectomy: a survey of the Western Vascular Society members.

To determine the prevalence, demographics and morbidity of vein patch rupture, the authors polled members of the Western Vascular Society. Forty-eight surgeons (53% of the members) reported an experience with 23,873 carotid operations. A vein patch was used in 1,760 operations (7.4%), and rupture of the patch occurred in 13 patients (0.7%), 10 women and three men. Indications for the patch were a small artery in 10 patients and restenosis in three. Saphenous vein was used for all patches and was harvested from the ankle in 12 patients and from the groin in one patient. All ruptures occurred from a split in the vein patch. Hypertension was present in seven of the 13 patients. None of the ruptures were associated with infection. Two ruptures occurred on the first postoperative day, six on the second day, three on the third day, one on the eighth day, and one on the twenty-first day. Four patients died: airway obstruction (1), hemorrhagic cerebral infarction (1), and myocardial infarction (2) were the causes. Three had a stroke and survived, one had a retinal embolus, and five underwent reoperation without complication. Vein patch of the carotid artery is used infrequently by members of the Western Vascular Society. The incidence of rupture of the patch is low (0.7%), but when it occurs, there is significant mortality (30.7%), and morbidity (30.7%). Patients with a vein patch should be observed in the hospital for three days after endarterectomy because rupture demands immediate reoperation.

Aged↗
PubMed1990

Challenges.

Explore the source record for details and available documents.

Delivery of Health Care↗
PubMed1990

Avoiding coagulopathy in vascular surgery.

The possibility of coagulopathy can be minimized by attending to certain general perioperative details to avoid hypothermia, hypotension-shock, and multiple transfusions. In this paper, we present our protocol for avoiding coagulopathy in vascular surgery. In the past 1 1/2 years, we have used perioperative plasmapheresis in 204 patients undergoing cardiac or aortic peripheral vascular surgery. Autologous platelet-rich plasma is transfused at the completion of the operation after heparin reversal. Our data show an approximate 50% reduction in homologous blood product requirement. Seventy-five percent of patients having aortic surgery received no homologous blood products during their hospital stay. For those undergoing cardiac surgery, there has been about a 45% reduction in the use of homologous blood products. In our experience, autologous platelet-rich plasma not only decreases the risk of transmittable disease, but promotes hemostasis.

Blood Coagulation↗
PubMed1989

The plasma collection system: a new concept in autotransfusion.

We have used the Haemonetics Cell-Saver autotransfusion technique in over 6,500 cases since 1979, salvaging more than 11,000 units of packed red blood cells. Major utilization has been in cardiac, vascular, and orthopedic cases. Coagulopathy associated with hypothermia, shock, multiple transfusions, and the autotransfusion technique, which removes clotting factors and platelets, often necessitated use of fresh-frozen plasma and platelet packs postoperatively to control bleeding and clotting problems. However, this defeats the prevention of disease transmission, transfusion reaction, and autoimmunization. Haemonetics has recently developed a plasma collection system which salvages up to 1,000 cc of platelet-rich plasma. Early experience suggests this technique will not only decrease the incidence of postoperative bleeding but further decrease the use of homologous (bank) blood and components. A step-by-step guide to the plasma collection system is discussed. The plasma collection system augments the present autotransfusion technique that conserves red blood cells, thus making complete autologous blood transfusion a reality.

Blood Transfusion, Autologous↗