Amira M. Safwat

Use of propranolol to control rate-pressure product during cardiac anesthesia.

The use of propranolol to control heart rate (HR), systolic pressure, and rate-pressure product (RPP) during laryngoscopy and sternotomy was studied in 21 patients, New York Heart Association functional Classes 1 and 2, scheduled for coronary artery bypass graft surgery. All patients were anesthetized in an identical fashion, but the treatment group (N = 13) received propranolol, 0.5 to 1 mg IV, 4 minutes before laryngoscopy and again, in most cases, before skin incision. Patients not given propranolol (N = 8) showed a clinically and statistically significant increase in HR and RPP, whereas HR and RPP remained essentially unchanged from the preanesthetic period in patients given propranolol.

No Evidence for Blood Flow Redistribution with Isoflurane or Halothane during Acute Coronary Artery Occlusion in Fentanyl-anesthetized Dogs

The present study examines the postulate that isoflurane, in contrast to halothane, causes redistribution of blood flow away from an ischemic myocardial region through vasodilation of adjacent normally perfused myocardium. The study was performed in open-chest dogs anesthetized with fentanyl; ischemia was induced by occlusion of the left anterior descending coronary artery. At 0.6% alveolar concentration, isoflurane increased transmural blood flow to 125% of control values (P less than 0.05) in the normal region without concomitant changes in blood flow to the ischemic region or in the endocardial/epicardial flow ratio in the ischemic region. The evidence excludes either transmural steal or regional redistribution phenomena. Myocardial blood flow variables returned to control values at 1.8% isoflurane, and no blood flow redistribution effects were evident. In contrast, whereas halothane 0.4% caused no significant effect on myocardial blood flows, an alveolar concentration of 1.2% decreased transmural blood flow to normally perfused left ventricle to 70% of control (P less than 0.05). Regional myocardial oxygen consumption in the normal and ischemic areas decreased at higher alveolar concentrations and was unchanged at the lower concentrations for both agents. Myocardial lactate production from the ischemic region was unchanged with either agent, suggesting that, in terms of metabolic changes, neither agent worsened ischemia during sustained occlusion of the left anterior descending coronary artery. The present data show no evidence for worsening of myocardial ischemia with either isoflurane or halothane. Isoflurane causes a relatively greater increase in perfusion compared to myocardial oxygen consumption of normally perfused myocardium; nevertheless, sufficient coronary vascular reserve remains in the native collateral circulation so that myocardial metabolic supply-and-demand relationships during ischemia are not further compromised.

Management of Jehovah's Witness patients for scoliosis surgery: the use of platelet and plasmapheresis

Four patients whose religious beliefs prohibited accepting blood during surgery for scoliosis were anesthetized and managed successfully using plateletpheresis and plasmapheresis. Blood losses were replaced with crystalloid and hetastarch solutions. In addition, a moderate hypotensive technique was used to minimize surgical blood loss. Postoperatively, the patients received iron therapy and/or erythropoietin. Three of these patients had an uncomplicated postoperative course, however, the fourth patient had some postoperative bleeding with initial hemodynamic instability. We believe that patients who refuse to receive blood transfusion during surgery because of religious beliefs or health issues can be managed safely using other alternatives and techniques such as plateletpheresis and plasmapheresis, which conserve and minimize blood loss. Each case should be assessed on an individual basis.

Intraoperative use of platelet-plasmapheresis in vascular surgery.

Abstract Study Objective: To determine, in a pilot study, whether pheresis of plasma and platelets before surgical blood loss, with reinfusion of the autologous plasma and platelets after completion of the aortic reconstruction, will result in decreased bleeding and decreased transfusion of allogenic blood components in patients undergoing elective aortic reconstruction. Design: Randomized study. Setting: University medical center. Interventions: Patients were randomized to perioperative (acute) platelet plasmapheresis (APP group) versus conventional blood component therapy (control group). In the APP group, blood was withdrawn after induction of anesthesia, to sequester approximately 300 mL of platelet rich plasma (PRP); platelet poor plasma (PPP) and red blood cells (RBC) were sequestered as well. An autotransfusion device was used to collect and re-infuse autologous RBC during the course of the operation in both groups. After completion of the aortic reconstruction, autologous PRP and PPP were re-infused in the APP group. Blood loss, volume of blood component transfusions, and preoperative and postoperative hemoglobin (Hb), hematocrit (Hct), platelet, international normalized ratio (INR), and activated partial thromboplastin time (aPTT) were recorded. Measurements and Main Results: There was no difference between groups in demographics, preoperative laboratory values, or surgical procedures, although more patients were treated for aneurysms (73% vs . 60%) and fewer for occlusive disease (20% vs . 40%) in the control versus APP group. Also, there were no differences between the control and APP groups in duration of operation, blood loss, volume of colloid infused, or volume of allogenic RBC and plasma transfused. Patients in the APP group received a greater volume of crystalloid solution (9.1 ± 3.4 L vs. 6.8 ± 3.0 L; p = 0.002), but fewer units of allogenic platelets than the control group (0.7 ± 1.0 units vs . 0.2 ± 0.4 units; p 3 / mm 3 vs. 182 ± 51 × 10 3 / mm 3 ; p = 0.004). Conclusions: Perioperative platelet plasmapheresis led to fewer allogenic platelet transfusions in patients undergoing elective aortic reconstruction. However, there was no decrease in blood loss and no reduction in transfusion of allogenic RBC or plasma. Perioperative platelet plasmapheresis is not recommended for routine use in elective aortic reconstruction.

Role of systemic arterial pressure, heart rate, and derived variables in prediction of severity of myocardial ischemia during acute coronary occlusion in anesthetized dogs.

The present study examined the postulate that the quotient of mean systemic arterial pressure and heart rate predicts the severity of myocardial ischemia during occlusion of the left anterior descending coronary artery. Studies were performed in open-chest fentanyl-anesthetized dogs before and during halothane (n = 8) or isoflurane (n = 8) anesthesia. The pressure-rate quotient (PRQ) decreased significantly in both groups during incremental increases in halothane or isoflurane to 68% and 57% of control values at 0.5 MAC and to 41% and 38% at 1.5 MAC for halothane and isoflurane, respectively. Myocardial lactate production was unchanged from the ischemic region, and no correlation between the PRQ and myocardial lactate production was observed. In contrast, heart rate correlated significantly (r = 0.376; P less than 0.05) with lactate production. The product of systolic systemic arterial pressure and heart rate (rate-pressure product) correlated with blood flow (r = 0.493; P less than 0.001) and with oxygen consumption (r = 0.571; P less than 0.001) in the normal myocardium. A weak correlation (r = 0.330; P less than 0.05) of rate-pressure product with myocardial lactate production from the ischemic region was observed. There were no correlations between the PRQ and myocardial lactate production from the ischemic region or indices of blood flow distribution (i.e., inner/outer ratio in the ischemic region or ischemic/normal ratio). The relationship of hemodynamic variables to measurements of regional myocardial metabolism was independent of background anesthetic agent of depth of anesthesia. The current data suggest that heart rate changes are weakly predictive of severity of myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Re-Evaluation of Renal Cell Carcinoma Tumor Thrombus Extension by Intraoperative Transesophageal Echocardiography

T RANSESOPHAGEAL ECHOCARDIOGRAPHY (TEE) is well accepted and extensively used by cardiologists, anesthesiologists, and cardiothoracic surgeons perioperatively to monitor cardiac function and great vessel anatomy.’ TEE remains underused in noncardiac surgical procedures, however. This oversight may be due, in part, to inadequate resources or the specialized training and qualifications necessary to perform TEE.* Alternatively, other physicians may be unfamiliar with its diagnostic capabilities. This case report describes a patient whose treatment was dramatically altered by perioperative TEE. He was brought to the operating room with a diagnosis of renal cell carcinoma and his preoperative diagnostic evaluation revealed extension of the tumor thrombus into the inferior vena cava and intrahepatic vessels. There was no tumor thrombus extension visualized above the level of the diaphragm by magnetic resonance imaging (MRI) or transthoracic echocardiography. The patient was brought to the operating room for a planned surgical resection of the tumor and subdiaphragmatic tumor thrombus.

The Intraoperative Use of Plateletpheresis: A Review

T HE FEAR of blood transmissible disease has led to various alternative blood conservation techniques that minimize blood loss and exposure to blood products. Preoperative autologous blood withdrawal has been widely practiced for elective orthopedic procedures. 1 However, this requires a lot of preparation and frequent patient visits to the blood bank center. In addition, blood is wasted when the autologous blood is not reinfused into the patient and cannot be used for another patient. This technique is also unsuitable for most cardiac patients, patients with anemia, and patients with other critical disease. The autotransfusion unit is a popular device used for intraoperative blood salvage. Pharmacologic agents such as desmopressin, tranexamic acid, epsilon-aminocaproic acid, and aprotinin have been widely used in cardiac surgery to produce hemostasis and minimize blood loss and usage. Recently, acute plateletpheresis (APP) has been reintroduced, mainly in cardiac surgery. This discussion will briefly describe the method used for intraoperative APP and the merits of the intraoperative use of this technique.

Intraoperative Use of Platelet-plasmapheresis in Vascular Surgery

STUDY OBJECTIVE To determine, in a pilot study, whether pheresis of plasma and platelets before surgical blood loss, with reinfusion of the autologous plasma and platelets after completion of the aortic reconstruction, will result in decreased bleeding and decreased transfusion of allogenic blood components in patients undergoing elective aortic reconstruction. DESIGN Randomized study. SETTING University medical center. INTERVENTIONS Patients were randomized to perioperative (acute) platelet plasmapheresis (APP group) versus conventional blood component therapy (control group). In the APP group, blood was withdrawn after induction of anesthesia, to sequester approximately 300 mL of platelet rich plasma (PRP); platelet poor plasma (PPP) and red blood cells (RBC) were sequestered as well. An autotransfusion device was used to collect and re-infuse autologous RBC during the course of the operation in both groups. After completion of the aortic reconstruction, autologous PRP and PPP were re-infused in the APP group. Blood loss, volume of blood component transfusions, and preoperative and postoperative hemoglobin (Hb), hematocrit (Hct), platelet, international normalized ratio (INR), and activated partial thromboplastin time (aPTT) were recorded. MEASUREMENTS AND MAIN RESULTS There was no difference between groups in demographics, preoperative laboratory values, or surgical procedures, although more patients were treated for aneurysms (73% vs. 60%) and fewer for occlusive disease (20% vs. 40%) in the control versus APP group. Also, there were no differences between the control and APP groups in duration of operation, blood loss, volume of colloid infused, or volume of allogenic RBC and plasma transfused. Patients in the APP group received a greater volume of crystalloid solution (9.1 +/- 3.4 L vs. 6.8 +/- 3.0 L; p = 0.002), but fewer units of allogenic platelets than the control group (0.7 +/- 1.0 units vs. 0.2 +/- 0.4 units; p < 0.04). There were no differences in postoperative Hb, Hct, INR, aPTT, or fibrinogen. The platelet count was lower in the APP group than in the control group (123 +/- 40 x 10(3)/mm(3) vs. 182 +/- 51 x 10(3)/mm(3); p = 0.004). CONCLUSIONS Perioperative platelet plasmapheresis led to fewer allogenic platelet transfusions in patients undergoing elective aortic reconstruction. However, there was no decrease in blood loss and no reduction in transfusion of allogenic RBC or plasma. Perioperative platelet plasmapheresis is not recommended for routine use in elective aortic reconstruction.

Quantified EEG Detects Ischemia: A Case Report

We have monitored 86 carotid endarterectomy and other neurovascular surgeries involving the carotid arteries with intraoperative digitized EEG over the past 59 months. A basic technique is described for the detection of intraoperative cerebral ischemia.