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T Ammar

Publications and source records attributed to T Ammar.

12 recordsLinked to original sources
PubMed2003

Cortical blindness and hepatic encephalopathy.

PURPOSE: To present a case of permanent cortical blindness (CB) following hepatic encephalopathy. METHODS: Systematic clinical examination and further investigations to elicit the diagnosis. CONCLUSION: Complete CB is an uncommon neurological disorder and is rarely persistent. In rare cases of hepatic encephalopathy, the visual cortex may be affected and CB may occur, which resolves following treatment of the hepatic encephalopathy. We report a previously unreported complication involving permanent CB following hepatic encephalopathy in a young man.

Adult↗
PubMed1999

Platelet-activated clotting time does not measure platelet reactivity during cardiac surgery.

BACKGROUND: Platelet dysfunction is a major contributor to bleeding after cardiopulmonary bypass (CPB), yet it remains difficult to diagnose. A point-of-care monitor, the platelet-activated clotting time (PACT), measures accelerated shortening of the kaolin-activated clotting time by addition of platelet activating factor. The authors sought to evaluate the clinical utility of the PACT by conducting serial measurements of PACT during cardiac surgery and correlating postoperative measurements with blood loss. METHODS: In 50 cardiac surgical patients, blood was sampled at 10 time points to measure PACT. Simultaneously, platelet reactivity was measured by the thrombin receptor agonist peptide-induced expression of P-selectin, using flow cytometry. These tests were temporally analyzed. PACT values, P-selectin expression, and other coagulation tests were analyzed for correlation with postoperative chest tube drainage. RESULTS: PACT and P-selectin expression were maximally reduced after protamine administration. Changes in PACT did not correlate with changes in P-selectin expression at any time interval. Total 8-h chest tube drainage did not correlate with any coagulation test at any time point except with P-selectin expression after protamine administration (r = -0.4; P = 0.03). CONCLUSIONS: The platelet dysfunction associated with CPB may be a result of depressed platelet reactivity, as shown by thrombin receptor activating peptide-induced P-selectin expression. Changes in PACT did not correlate with blood loss or with changes in P-selectin expression suggesting that PACT is not a specific measure of platelet reactivity.

Adult↗
PubMed1998

Factors that influence early extubation: bleeding.

Excessive bleeding after cardiac surgery is an important factor that can prevent early extubation. Hemostatic derangement is well recognized to be associated with cardiopulmonary bypass, with many possible contributing factors resulting in coagulation defects and fibrinolytic pathway activation. Measures to optimize hemostasis are critical when managing patients for whom early extubation and hospital discharge are goals. The intraoperative evaluation of the hemostatic system with tests like the thrombelastogram and the use of therapeutic agents such as aprotinin are simple, safe, and effective methods of achieving these goals.

Aprotinin↗
PubMed1997

In vitro effects of the platelet glycoprotein IIb/IIIa receptor antagonist c7E3 Fab on the activated clotting time.

BACKGROUND: In the evaluation of 7E3 for the Prevention of Ischemic Complications study (EPIC), the activated coagulation (clotting) times (ACTs) were longer in heparinized patients treated with c7E3 Fab than in those treated with placebo. The present study was designed to further investigate this observation by assessing whether the in vitro addition of c7E3 Fab to blood would affect the ACT. METHODS AND RESULTS: Native or heparinized blood obtained from normal volunteers was preincubated with antibodies c7E3 Fab (anti-GPIIb/IIIa and anti-alpha v beta 3), 10E5 (anti-GPIIb/IIIa), or LM609 (anti-alpha v beta 3). The ACTs of the heparinized, but not native samples were significantly prolonged by the addition of c7E3 Fab and 10E5 but not LM609, indicating that the prolongation was due to GPIIb/IIIa blockade. The addition of c7E3 Fab also significantly prolonged the ACTs of blood anticoagulated with the direct thrombin inhibitors hirudin and D-phenylalanyl-L-prolyl-L-arginyl chloromethyl ketone, indicating that the effect of c7E3 Fab was not exclusively related to decreased release of PF4, a heparin-neutralizing factor, from platelets. CONCLUSIONS: These data support the conclusion that the prolongation of the ACT in patients in EPIC was due to c7E3 Fab blockade of GPIIb/IIIa receptors. This raises the possibility that in vivo c7E3 Fab functions not only as an antiplatelet agent but also as an anticoagulant; direct in vivo data will, however, be required for assessment of this possibility.

Abciximab↗
PubMed1997

The effects of heparinase 1 and protamine on platelet reactivity.

BACKGROUND: Protamine is currently the most widely used drug for the reversal of heparin anticoagulation. Heparinase 1 (heparinase) is being evaluated as a possible alternative to protamine for the reversal of heparin anticoagulation. The authors evaluated the effects of equivalent doses of heparinase and protamine on platelet reactivity by measuring agonist-induced P-selectin expression. METHODS: After Institutional Review Board (IRB) approval, informed consent was obtained from 12 healthy volunteers and 8 patients undergoing surgery requiring cardiopulmonary bypass (CPB). Twenty-four ml of blood was obtained from each volunteer; 10 ml of blood was obtained from each patient before the CPB, and another 10 ml was obtained after CPB. Heparin was neutralized using heparinase or protamine. Platelet reactivity was assessed by measuring the expression of P-selectin after stimulation of platelets with increasing concentrations of a thrombin receptor agonist peptide (TRAP). Data were analyzed using analysis of variance. P < 0.05 was considered significant. RESULTS: For the healthy volunteers, the activated coagulation times (ACTs) of the heparinized samples returned to baseline values with heparinase (12.5 U/ml) or protamine (32.5 microg/ml). For the 8 patients, the ACTs returned to baseline with heparinase (20 U/ml) or protamine (50 microg/ml). The authors found no difference in the expression of P-selectin in samples neutralized with heparinase, but samples neutralized with protamine showed a significant decrease in the expression of P-selectin when compared with heparinized samples. CONCLUSIONS: At dosages that reverse the anticoagulant effects of heparin, heparinase has minimal effects on platelets, whereas platelet reactivity was markedly inhibited by protamine.

Adult↗
PubMed1996

Tranexamic acid reduces transfusions and mediastinal drainage in repeat cardiac surgery.

The administration of tranexamic acid (TA) prior to cardiopulmonary bypass (CPB) has been associated with reduced bleeding during and after cardiac surgery. In a prospective, randomized, controlled, double-blind clinical trial, adult patients undergoing repeat open heart surgery received TA (n = 17) or an equal volume of saline placebo (n = 13). In the TA group, a 20-mg/kg intravenous (IV) initial dose of TA at akin incision was followed by an infusion of 2 mg.kg-1.h-1, which continued for the duration of the surgical procedure. Identical transfusion guidelines were followed in both groups. Routine coagulation tests, D-dimer levels, mediastinal tube drainage, and transfusion requirements were compared. Cumulative postoperative mediastinal tube drainage measured at 24 h was 649 +/- 391 mliter (mean +/- SD) in the TA group compared with 923 +/- 496 mliter in the placebo group (P < 0.01). Forty-eight-and 72-h mediastinal tube drainage were also significantly less in the TA group (P < 0.01). Seven of 17 TA patients received to transfusion of allogeneic blood products compared with 1 of 13 placebo patients (P = 0.047). The incidence and volumes of platelet and fresh frozen plasma transfusion in the TA group were not significantly different in comparison with the placebo group. The perioperative increase in D-dimer levels (post-CPB minus pre-CPB) in the placebo group (median difference = 675 ng/mliter, range 125-1648) was significantly more than in the TA group (median difference = 182 ng/mliter, range -426-1950; P = 0.003). Sternal closure occurred in 41 +/- 21 min in the TA group and 61 +/- 49 min in the placebo group (P = 0.14), and the subjective bleeding score was less in the TA group than in the placebo group (2.38 +/- 0.78 vs 3.08 +/- 1.04; P = 0.045). The data from the current study support the prophylactic use of TA in patients undergoing repeat cardiac surgery. TA administered prior to CPB reduced the incidence of allogeneic transfusions and postoperative mediastinal tube drainage, and improved the subjective assessment of post-CPB hemostasis in a group of patients at moderately high risk for perioperative bleeding.

Adult↗
PubMed1996

The effects of thrombocytopenia on the activated coagulation time.

The activated coagulation (clotting) time (ACT) is widely used to monitor heparin therapy during cardiopulmonary bypass (CPB). Since thrombocytopenia occurs during and for some time after CPB, we considered the possibility that thrombocytopenia may affect the ACT. Blood samples were obtained from 12 healthy volunteers. Thrombocytopenic samples were created by a differential centrifugation technique. Blood samples from five thrombocytopenic patients were also studied. The platelet counts of the control citrated whole blood samples were 254,000 +/- 35,000/microL (mean +/- SD), whereas the platelet counts of the thrombocytopenic citrated samples were 49,000 +/- 8000/microL. There were no significant differences in the ACTs between these two groups (143 +/- 8 vs 145 +/- 9 s, respectively, P = 0.16). There were also no significant differences in the ACTs of the heparinized control samples compared with the ACTs of the heparinized thrombocytopenic samples. The platelet counts of the five thrombocytopenic patients were 43,000, 18,000, 16,000, 8000, and 7000/microL, and the ACTs of the unanticoagulated samples were 162, 240, 191, 210, and 215s, respectively. We conclude that the ACT is not affected by moderate thrombocytopenia and therefore this test may be used in patients who are moderately thrombocytopenic.

Anticoagulants↗
PubMed1995

Cardiopulmonary bypass for adult patients: a survey of equipment and techniques.

OBJECTIVES: The techniques and equipment used for cardiopulmonary bypass for adult cardiac surgery vary among institutions and may change over time. This study sought to document the changing patterns of practice. DESIGN: Voluntary survey of meeting participants. SETTING: 13th Annual San Diego Cardiothoracic Surgery Symposium (February 1993). PARTICIPANTS: There were 331 responses from perfusionists (79.5%), cardiac surgeons (11.2%), and anesthesiologists (6.3%). The majority of these participants were from institutions where more than 1,000 cardiac operations were performed annually. MEASUREMENTS AND MAIN RESULTS: It was found that 91.5% of the respondents used membrane oxygenators currently, compared with 5% in 1982 (as reported in a previous survey). Over 80% of the institutions surveyed used some type of perioperative cell-salvaging technique. Arterial line filters were used by 92% of the respondents compared with 64% in 1982. Also, 80% of the respondents were aware of the availability of leukocyte-depleting filters. CONCLUSIONS: The probable reasons for the increased utilization of membrane oxygenators and arterial line filters include less damage to the formed elements of blood, fewer gaseous microemboli, and better control of carbon dioxide elimination and oxygenation. The authors anticipate that future surveys will document increased use of leukocyte-depleting filters because of the literature implicating neutrophils as mediators of tissue destruction in various disease processes, including myocardial reperfusion injury.

Adult↗