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Biomedical subjects

R E Rawitscher

Publications and source records attributed to R E Rawitscher.

15 recordsLinked to original sources
PubMed1991

Benefit from combining blood conservation measures in cardiac operations.

Conventional blood conservation techniques have been insufficient to decrease transfusion needs in increasingly complex cardiac operations. To evaluate combinations of conservation techniques, 300 patients were divided into three equal groups. Group 1 had intraoperative autotransfusion and return of mediastinal drainage for 4 hours postoperatively. Group 2 had these measures plus intraoperative plasmapheresis. These two groups were given a transfusion for a hematocrit of less than 0.21 on cardiopulmonary bypass. Group 3 was treated with the same measures as group 2 but did not receive transfusions while on pump unless the hematocrit decreased to less than 0.15. The percentage of patients in each group given transfusions in the operating room was 34% in group 1, 28% in group 2, and 7% in group 3 (p less than 0.05). The percentage of all patients receiving transfusions during hospitalization was 68% in group 1, 36% in group 2 (p less than 0.05), and 18% in group 3 (p less than 0.05). Average total units transfused were 2.16 +/- 0.25 in group 1, 0.7 +/- 0.15 in group 2 (p less than 0.05), and 0.37 +/- 0.07 in group 3 (p less than 0.05). The perioperative morbidity rates including myocardial infarctions and strokes were similar. There were no deaths in group 3. Combining complementary conservation measures is effective in reducing homologous blood transfusions, and the need for transfusion can be safely reduced by allowing profound hemodilution during bypass.

Aged↗
PubMed1990

Effects of intraoperative plasmapheresis on blood loss in cardiac surgery.

Intraoperative platelet-rich plasmapheresis allows autotransfusion of fresh, undamaged platelets and clotting factors at the completion of the operation. To evaluate this technology, we randomly assigned 100 consecutive patients who were to undergo an elective coronary bypass procedure and had normal clotting studies into the experimental (plasmapheresis) or the control group. Characteristics of both groups were similar, including average age (61.4 years versus 61.3 years [experimental versus control group]), sex (78% male versus 74% male), preoperative weight (80.9 kg versus 80.2 kg), preoperative red cell mass (1,989 mL versus 1,890 mL), perfusion time (102 minutes versus 106 minutes), and coagulation studies. Both internal mammary arteries were used in 68% of the patients. All patients had preoperative and postoperative blood volume determinations and complete clotting studies. Sixty-two variables related to bleeding were analyzed. Strict indications for transfusion were a hemoglobin level less than 7 g/100 mL in patients younger than 70 years and a hemoglobin level less than 8 g/100 mL in patients older than 70 years. The group receiving intraoperative plasmapheresis had a significant reduction in operative red cell mass loss (1,050 +/- 43 mL versus 1,226 +/- 61 mL; p = 0.021), a reduction in the average homologous transfusion (0.67 +/- 0.15 unit versus 1.8 +/- 0.25 units; p = 0.0002), and an increase in the percentage of patients not requiring blood transfusions (66% versus 32%; p = 0.001). This technique is useful in reducing postoperative blood loss and homologous transfusions.

Blood Coagulation↗
PubMed1977

Prospective evaluation for pneumonectomy using the 99mtechnetium quantitative perfusion lung scan.

We evaluated 33 high-risk patients before pneumonectomy, all of whom had a forced expiratory volume in one second (FEV1) of less than 2.0 L before surgery. A quantitative perfusion lung scan was used to assess the right-left distribution of blood flow. A predicted postoperative FEV1 was calculated from the information on the lung scan and the preoperative FEV1. If this calculated value exceeded 800 ml, the patient was physiologically cleared for surgery up to and including a pneumonectomy. Surgery was otherwise believed to be contraindicated in the absence of studies using balloon occlusion. Perioperative mortality (less than or equal to 30 days after surgery) was found to be 15 percent (5/33). In surgery of this magnitude, we find this to be an acceptable percentage of mortality and have continued to use these simple physiologic criteria to determine whether a patient can tolerate pneumonectomy.

Aged↗
PubMed1975

Changes in arterial pressure, viscosity and resistance during cardiopulmonary bypass.

Large changes in arterial pressure and systemic vascular resistance are frequently observed at the onset of and during cardiopulmonary bypass, particularly when hemodilution is employed. In order to assess the extent to which these changes are induced by changes in blood viscosity, we measured viscosity, pressure, and flow in a series of 17 patients. Hemodilution was used in Group A (12 patients) but not in Group B (5 patients). At the beginning of cardiopulmonary bypass, the arteriovenous pressure difference decreased an average of 53.8 per cent in the Group A patients, concomitant with a 41.7 per cent decrease in blood viscosity. The arteriovenous pressure difference in the Group B patients increased an average of 6.4 per cent, while the blood viscosity increased by 8 per cent. A nomogram was theoretically derived for the Group A patients, which allows rapid estimation of the extent of viscosity-induced hypotension for a given volume of priming fluid, initial patient hematocrit, and patient weight. After correction for viscosity changes due to hemodilution, the Group A patients were found to exhibit essentially normal values of systemic vascular resistance at the start of bypass, with a mean of 1,155 dynes-sec./cm.5. On the other hand, the Group B patients had elevated resistance values, with a mean of 1,611 dynes-sec./cm.5. During perfusion, the resistance of both groups tended to increase, sometimes by 100 per cent or more. In some cases, however, the resistance values changed in an erratic fashion. These effects were not due to changes in blood viscosity.

Adolescent↗
PubMedDate not supplied

Effects of hemodilution on hypotention during cardiopulmonary bypass.

Arterial pressure, systemic vascular resistance, and viscosity measurements were made on 20 patients, during cardiopulmonary bypass with hemodilution to an average hematocrit reduction of 48 plus or minus 12 percent. The arterial pressure and blood viscosity decreased an average of 56 plus or minus 16 percent and 40 plus or minus 12 percent, respectively. The total peripheral resistance following the start of bypass was significantly below normal (p smaller than 0.005), but not when corrected for the change in viscosity. There was a strong correlation between the extent of pressure reduction and the viscosity decrease with hemodilution (p smaller than 0.01), although not all the changes in pressure could be accounted for in terms of viscosity. There was no apparent correlation between the extent of hypotension as measured by the area of the pressure-time curve below 50 mm. Hg and the presence or absence of postoperative cerebral or cardiac complications, in contrast to other recent reports.

Adolescent↗
PubMedDate not supplied

A prospective study of aspirin's effect on red blood cell loss in cardiac surgery.

The effect of aspirin on red blood cell (RBC) loss and blood transfusions was evaluated prospectively in 100 consecutive patients, with normal bleeding times, undergoing elective coronary artery bypass (CABG) surgery. Patients taking 85-325 mgm of aspirin daily up to or within 48 hours of surgery (the "aspirin" group) were compared to patients not taking aspirin or those who had discontinued aspirin at least 4 days before surgery (the "no-aspirin" group). RBC loss was determined by measuring preoperative and postoperative RBC volume using RISA and 51Cr techniques. There were no significant differences, respectively, between the aspirin and no-aspirin groups for: RBC loss (1158 +/- 67 ml vs 1129 +/- 47 ml, p = 0.737), chest tube drainage (925 +/- 31 ml vs 844 +/- 70 ml, p = 0.553), and gm% discharge Hemoglobin (Hgb) (9.94 +/- 0.32 vs 9.49 +/- 1.4, p = 0.0148). Strict criteria for blood transfusions were employed: (1) intraoperative hematocrit of less than 21%, (2) postoperative Hgb of less than 7 gm% for patients less than 70 years old and (3) postoperative Hgb of less than 8 gm% for patients greater than 70 years old. There were no significant differences, respectively, between the aspirin and no-aspirin groups for units of blood transfused (1.32 +/- vs 1.21 +/- 0.20, p = 0.843) and patients not receiving transfusions during the entire hospitalization (44% vs 50%). Patients taking 85-325 mgm of aspirin with a normal bleeding time undergoing elective CABG did not have increased RBC loss or increased transfusion requirements. These results indicate it is not necessary to delay elective CABG surgery for the purpose of discontinuing aspirin.

Aspirin↗