Title Tranexamic Acid and Aprotinin in Primary Cardiac Operations: An Analysis of 220 Cardiac Surgical Patients Treated with Tranexamic Acid or Aprotinin.[Miscellaneous Article]
Source Anesthesia & Analgesia. 107(5):1469-1478, November 2008.
Abstract BACKGROUND: Antifibrinolytics are widely used in cardiac surgery to reduce bleeding. Allogeneic blood transfusion, even in primary cardiac operations with low blood loss, is still high. In the present study we evaluated the impact of tranexamic acid compared to aprotinin on the transfusion incidence in cardiac surgical patients with low risk of bleeding.
METHODS: This prospective, randomized, double-blind study included 220 patients undergoing primary coronary artery revascularization (coronary artery bypass grafting [CABG]) or aortic valve replacement (AVR). Randomized in blocks of 20, patients received either tranexamic acid (approximately 6 g) or full-dose aprotinin (approximately 5-6 x 106 Kallikrein Inhibiting Units). Transfusion was guided by a strict transfusion algorithm. Molecular markers of hemostasis were determined to assess differences in the mode of action of the two drugs. Primary end-points were the incidence of allogeneic red cell transfusion and 24-h postoperative blood loss. Data were analyzed according to the intention-to-treat principle and compared using the [chi]2 and Mann-Whitney U-test.
RESULTS: Two-hundred-twenty patients were enrolled (CABG: 134, AVR: 86). In the aprotinin Group 47% of patients received allogeneic blood during the hospital stay as compared to 61% in the tranexamic acid group (P = 0.036). Aprotinin conferred a 23% reduction in allogeneic transfusion risk (RR 0.77, 95% CI 0.53-0.88). Overall, no significant difference in postoperative bleeding was observed, although 24-h blood loss was reduced in aprotinin-treated CABG patients (500, 350-750 mL vs 650, 475-875 mL (median, 25th-75th percentile); P = 0.039). Despite the lower transfusion rate, the hemoglobin concentration on the first postoperative day was higher in the aprotinin group (11.3, 9.9-12.1 vs 10.6, 9.9-11.6 mg/dL; P = 0.023). The fibrinolytic activity at the end of operation determined by D-Dimer was comparable in both groups. (0.15, 0.11-0.17 mg/L [aprotinin] versus 0.18, 0.12-0.24 mg/L [tranexamic acid]). The activated partial thromboplastin time was prolonged up to 4 h postoperatively in the aprotinin group, while the heparin requirement was reduced: 19% of the patients in the aprotinin group and 45% in the tranexamic acid group received at least one additional bolus heparin during cardiopulmonary bypass (P < 0.001). Troponin T levels postoperatively and on postoperative day 1 were significantly higher in the tranexamic acid group (P = 0.017). No differences in renal, cardiac, or mortality outcomes were observed.
CONCLUSION: Considering the rate of transfusion of red blood cells, tranexamic acid was slightly inferior in patients undergoing CABG, but there was no difference in patients receiving AVR. Tranexamic acid seems to be less effective in operations with increased bleeding such as CABG. Clinical benefit depends on specific patient and institution characteristics ( ClinicalTrials.gov NCT00396760).
(C) 2008 by International Anesthesia Research Society.
DOI Number 10.1213/ane.0b013e318182252b
domingo, 9 de novembro de 2008
A Thromboelastometric Evaluation of the Effects of Hypothermia on the Coagulation System.
Title A Thromboelastometric Evaluation of the Effects of Hypothermia on the Coagulation System.[Miscellaneous Article]
Source Anesthesia & Analgesia. 107(5):1465-1468, November 2008.
Abstract BACKGROUND: Hypothermia may be accidental or therapeutic. Therapeutic hypothermia is increasingly used as treatment for various conditions, e.g., neuroprotection after cardiac arrest. Hypothermia leads to an impairment of the coagulation system, but the degree of impairment has been difficult to determine. Most studies have been performed on plasma instead of whole blood. We therefore evaluated whole blood investigating the effects of hypothermia on the coagulation system over a wide range of temperatures (25-40[degrees]C).
METHODS: Blood was drawn from six healthy volunteers into citrated test tubes. Samples were then placed in water baths with temperatures ranging from 25 to 40[degrees]C for 30 min before the coagulation system was studied using rotational thromboelastometry. A contact activator (Ellagic acid) was used for initiation of coagulation. Clotting time, clot formation time, [alpha] angle, and maximum clot strength were measured. All tests were run for 60 min and they were performed at the same temperature as the temperature in the water bath.
RESULTS: Coagulation was increasingly impaired with decreasing temperatures in the temperature range studied. All variables measured were significantly impaired in a stepwise pattern (P < 0.0001).
CONCLUSIONS: Evaluation using a whole blood analysis shows that hypothermia progressively impairs the coagulation system.
(C) 2008 by International Anesthesia Research Society.
DOI Number 10.1213/ane.0b013e31817ee955
Source Anesthesia & Analgesia. 107(5):1465-1468, November 2008.
Abstract BACKGROUND: Hypothermia may be accidental or therapeutic. Therapeutic hypothermia is increasingly used as treatment for various conditions, e.g., neuroprotection after cardiac arrest. Hypothermia leads to an impairment of the coagulation system, but the degree of impairment has been difficult to determine. Most studies have been performed on plasma instead of whole blood. We therefore evaluated whole blood investigating the effects of hypothermia on the coagulation system over a wide range of temperatures (25-40[degrees]C).
METHODS: Blood was drawn from six healthy volunteers into citrated test tubes. Samples were then placed in water baths with temperatures ranging from 25 to 40[degrees]C for 30 min before the coagulation system was studied using rotational thromboelastometry. A contact activator (Ellagic acid) was used for initiation of coagulation. Clotting time, clot formation time, [alpha] angle, and maximum clot strength were measured. All tests were run for 60 min and they were performed at the same temperature as the temperature in the water bath.
RESULTS: Coagulation was increasingly impaired with decreasing temperatures in the temperature range studied. All variables measured were significantly impaired in a stepwise pattern (P < 0.0001).
CONCLUSIONS: Evaluation using a whole blood analysis shows that hypothermia progressively impairs the coagulation system.
(C) 2008 by International Anesthesia Research Society.
DOI Number 10.1213/ane.0b013e31817ee955
The effects of interrupted or continuous administration of sevoflurane on preconditioning before cardio-pulmonary bypass in coronary artery surgery: c
The effects of interrupted or continuous administration of sevoflurane on preconditioning before cardio-pulmonary bypass in coronary artery surgery: comparison with continuous propofol.[Article]
Source Anaesthesia. 63(10):1046-1055, October 2008.
Abstract Summary: Volatile anaesthetics have been shown to exert cardioprotective properties in experimental and clinical studies. However, the mode of administration may influence these cardioprotective effects. The present study was designed to compare the effect of interrupted administration of sevoflurane before cardiopulmonary bypass with continuous sevoflurane administration and with propofol-only anaesthesia, on cardioprotection as assessed by left ventricular performance and myocardial cell damage during coronary artery bypass grafting. Forty-two patients scheduled for coronary bypass surgery were randomly assigned to one of three groups: propofol-only (P; n = 14), continuous (SevoC; n = 14) and interrupted sevoflurane administration (SevoI; n = 14). Myocardial cell damage as assessed by Troponin T (cTNT) and creatine kinase MB (CK-MB) were chosen as the primary endpoints and echocardiographic myocardial performance index (MPI) measurements were also performed. Up to 48 h postoperatively, in group SevoI, postoperative cTNT values (mean (SD) 0.13 (0.04) ng.ml-1) were significantly (p < 0.05) lower than both the P (0.26 (0.31) ng.ml-1) and SevoC (0.25 (0.17) ng.ml-1) groups. CK-MB levels were also significantly (p < 0.05) lower in the SevoI group at 24 h after surgery and MPI significantly improved compared with both the P and SevoC groups. There was, however, no difference with respect to cytokine release and length of stay in either the intensive care unit or in the hospital. We conclude that prior interrupted sevoflurane administration confers some cardioprotection as compared with continuous sevoflurane administration or propofol-based anaesthesia.
(C) 2008 Association of Anaesthetists of Great Britain & Ireland
Source Anaesthesia. 63(10):1046-1055, October 2008.
Abstract Summary: Volatile anaesthetics have been shown to exert cardioprotective properties in experimental and clinical studies. However, the mode of administration may influence these cardioprotective effects. The present study was designed to compare the effect of interrupted administration of sevoflurane before cardiopulmonary bypass with continuous sevoflurane administration and with propofol-only anaesthesia, on cardioprotection as assessed by left ventricular performance and myocardial cell damage during coronary artery bypass grafting. Forty-two patients scheduled for coronary bypass surgery were randomly assigned to one of three groups: propofol-only (P; n = 14), continuous (SevoC; n = 14) and interrupted sevoflurane administration (SevoI; n = 14). Myocardial cell damage as assessed by Troponin T (cTNT) and creatine kinase MB (CK-MB) were chosen as the primary endpoints and echocardiographic myocardial performance index (MPI) measurements were also performed. Up to 48 h postoperatively, in group SevoI, postoperative cTNT values (mean (SD) 0.13 (0.04) ng.ml-1) were significantly (p < 0.05) lower than both the P (0.26 (0.31) ng.ml-1) and SevoC (0.25 (0.17) ng.ml-1) groups. CK-MB levels were also significantly (p < 0.05) lower in the SevoI group at 24 h after surgery and MPI significantly improved compared with both the P and SevoC groups. There was, however, no difference with respect to cytokine release and length of stay in either the intensive care unit or in the hospital. We conclude that prior interrupted sevoflurane administration confers some cardioprotection as compared with continuous sevoflurane administration or propofol-based anaesthesia.
(C) 2008 Association of Anaesthetists of Great Britain & Ireland
sexta-feira, 14 de setembro de 2007
Revisão foramen Oval -achado cirurgico
Title The Incidental Finding of a Patent Foramen Ovale During Cardiac Surgery: Should It Always Be Repaired? A Core Review.[Review]
Source Anesthesia & Analgesia. 105(3):602-610, September 2007.
Abstract With the increased use of intraoperative transesophageal echocardiography, patent foramen ovale (PFO) has become a common finding during heart surgery. This finding presents a difficult dilemma for cardiac surgeons, since the impact of intraoperatively diagnosed PFOs on postoperative outcome is unknown. Changes in the surgical plan required for closure of a PFO subject the patient to the possibility of additional risk. On the other hand, a decision to not close a PFO exposes the patient to unclear immediate and long-term consequences. Deciding whether or not to close a PFO currently depends on the clinicians' personal preferences, the probability of intraoperative and postoperative hypoxemia, and any anticipated deviation from the initial surgical plan. Most clinicians agree that an intraoperatively diagnosed PFO must be closed when surgery leads to a high risk of hypoxemia (e.g., left ventricular assist devices placement, heart transplantation); should be closed in most cases when minimal deviation from the initial surgical plan is needed for PFO closure (e.g., mitral valve or tricuspid valve surgeries); and probably, should be closed during heart surgeries performed without atriotomy and bicaval cannulation when the risk of perioperative or remote PFO-related complications is increased. The recent development of percutaneous methods of PFO closure provides a valuable backup for those cases when PFO is not closed and postoperative hypoxemia or other complications may be attributable to the uncorrected PFO.
(C) 2007 by International Anesthesia Research Society.
Source Anesthesia & Analgesia. 105(3):602-610, September 2007.
Abstract With the increased use of intraoperative transesophageal echocardiography, patent foramen ovale (PFO) has become a common finding during heart surgery. This finding presents a difficult dilemma for cardiac surgeons, since the impact of intraoperatively diagnosed PFOs on postoperative outcome is unknown. Changes in the surgical plan required for closure of a PFO subject the patient to the possibility of additional risk. On the other hand, a decision to not close a PFO exposes the patient to unclear immediate and long-term consequences. Deciding whether or not to close a PFO currently depends on the clinicians' personal preferences, the probability of intraoperative and postoperative hypoxemia, and any anticipated deviation from the initial surgical plan. Most clinicians agree that an intraoperatively diagnosed PFO must be closed when surgery leads to a high risk of hypoxemia (e.g., left ventricular assist devices placement, heart transplantation); should be closed in most cases when minimal deviation from the initial surgical plan is needed for PFO closure (e.g., mitral valve or tricuspid valve surgeries); and probably, should be closed during heart surgeries performed without atriotomy and bicaval cannulation when the risk of perioperative or remote PFO-related complications is increased. The recent development of percutaneous methods of PFO closure provides a valuable backup for those cases when PFO is not closed and postoperative hypoxemia or other complications may be attributable to the uncorrected PFO.
(C) 2007 by International Anesthesia Research Society.
Revisão heparina e trombocitopenia
Title Reducing Thrombotic Complications in the Perioperative Setting: An Update on Heparin-Induced Thrombocytopenia.[Review]
Source Anesthesia & Analgesia. 105(3):570-582, September 2007.
Abstract Heparins are widely used in the perioperative setting. Immune heparin-induced thrombocytopenia (HIT) is a serious, antibody-mediated complication of heparin therapy that occurs in approximately 0.5%-5% of patients treated with heparin for at least 5 days. An extremely prothrombotic disorder, HIT confers significant risks of thrombosis and devastating consequences on affected patients: approximately 38%-76% develop thrombosis, approximately 10% with thrombosis require limb amputation, and approximately 20%-30% die within a month. HIT antibodies are transient and typically disappear within 3 mo. In patients with lingering antibodies, however, re-exposure to heparin can be catastrophic. In the perioperative setting, heightened awareness is important for the prompt recognition, diagnosis, and treatment of HIT. HIT should be considered if the platelet count decreases 50% and/or thrombosis occurs 5-14 days after starting heparin, with other diagnoses excluded. On strong clinical suspicion of HIT, heparin should be discontinued and a parenteral alternative anticoagulant initiated, even before laboratory confirmation of HIT is obtained. Subsequent laboratory test results may help with the decision to continue with nonheparin therapy or switch back to heparin. Heparin avoidance in patients with current or previous HIT is feasible in most clinical situations, except perhaps in cardiovascular surgery. If the surgery cannot be delayed until HIT antibodies have disappeared, intraoperative alternative anticoagulation is recommended.
(C) 2007 by International Anesthesia Research Society.
Source Anesthesia & Analgesia. 105(3):570-582, September 2007.
Abstract Heparins are widely used in the perioperative setting. Immune heparin-induced thrombocytopenia (HIT) is a serious, antibody-mediated complication of heparin therapy that occurs in approximately 0.5%-5% of patients treated with heparin for at least 5 days. An extremely prothrombotic disorder, HIT confers significant risks of thrombosis and devastating consequences on affected patients: approximately 38%-76% develop thrombosis, approximately 10% with thrombosis require limb amputation, and approximately 20%-30% die within a month. HIT antibodies are transient and typically disappear within 3 mo. In patients with lingering antibodies, however, re-exposure to heparin can be catastrophic. In the perioperative setting, heightened awareness is important for the prompt recognition, diagnosis, and treatment of HIT. HIT should be considered if the platelet count decreases 50% and/or thrombosis occurs 5-14 days after starting heparin, with other diagnoses excluded. On strong clinical suspicion of HIT, heparin should be discontinued and a parenteral alternative anticoagulant initiated, even before laboratory confirmation of HIT is obtained. Subsequent laboratory test results may help with the decision to continue with nonheparin therapy or switch back to heparin. Heparin avoidance in patients with current or previous HIT is feasible in most clinical situations, except perhaps in cardiovascular surgery. If the surgery cannot be delayed until HIT antibodies have disappeared, intraoperative alternative anticoagulation is recommended.
(C) 2007 by International Anesthesia Research Society.
sábado, 25 de agosto de 2007
Sedação em POI cardiopatia congenita em UTI
Title Remifentanil-midazolam sedation for paediatric patients receiving mechanical ventilation after cardiac surgery+.[Miscellaneous Article]
Source BJA: British Journal of Anaesthesia. 99(2):252-261, August 2007.
Abstract Background: Sedation of critically ill children requiring artificial ventilation remains a therapeutic challenge due to large individual variation in drug effects and a paucity of knowledge of pharmacokinetics in this population. This study aimed to determine the pharmacokinetics of remifentanil in children requiring ventilation after cardiac surgery.
Methods: Twenty-six ventilated children aged 1 month to 9.25 yr (median 1.77 yr) who had undergone cardiac surgery were sedated with a fixed rate infusion of midazolam 50 [micro]g kg-1 h-1 and a remifentanil infusion that was commenced at 0.8 [micro]g kg-1 min-1 for a minimum of 60 min and subsequently decreased by 0.1 [micro]g kg-1 min-1every 20 min until the patient awoke. Arterial blood concentrations of remifentanil and midazolam were measured using high-performance liquid chromatography. Mixed-effects population models were fitted to the remifentanil concentration-time data.
Results: Satisfactory sedation was achieved in all patients as assessed by Comfort score during the initial maintenance and reduction phase of the remifentanil infusion. One patient was withdrawn from the study due to hypotension. Remifentanil pharmacokinetics were best described using a two-compartment allometric model. For a typical child with a body weight of 10.5 kg, clearance was 68.3 ml kg-1 min-1, intercompartmental clearance was 80 ml kg-1 min-1, the central compartment volume was 91.7 ml kg-1, and the peripheral compartment volume was 141 ml kg-1.
Conclusions: A combination of remifentanil and midazolam provided satisfactory sedation for these patients. Owing to enhanced clearance rates, smaller (younger) children will require higher remifentanil infusion rates than larger (older) children and adults to achieve equivalent blood concentrations.
Source BJA: British Journal of Anaesthesia. 99(2):252-261, August 2007.
Abstract Background: Sedation of critically ill children requiring artificial ventilation remains a therapeutic challenge due to large individual variation in drug effects and a paucity of knowledge of pharmacokinetics in this population. This study aimed to determine the pharmacokinetics of remifentanil in children requiring ventilation after cardiac surgery.
Methods: Twenty-six ventilated children aged 1 month to 9.25 yr (median 1.77 yr) who had undergone cardiac surgery were sedated with a fixed rate infusion of midazolam 50 [micro]g kg-1 h-1 and a remifentanil infusion that was commenced at 0.8 [micro]g kg-1 min-1 for a minimum of 60 min and subsequently decreased by 0.1 [micro]g kg-1 min-1every 20 min until the patient awoke. Arterial blood concentrations of remifentanil and midazolam were measured using high-performance liquid chromatography. Mixed-effects population models were fitted to the remifentanil concentration-time data.
Results: Satisfactory sedation was achieved in all patients as assessed by Comfort score during the initial maintenance and reduction phase of the remifentanil infusion. One patient was withdrawn from the study due to hypotension. Remifentanil pharmacokinetics were best described using a two-compartment allometric model. For a typical child with a body weight of 10.5 kg, clearance was 68.3 ml kg-1 min-1, intercompartmental clearance was 80 ml kg-1 min-1, the central compartment volume was 91.7 ml kg-1, and the peripheral compartment volume was 141 ml kg-1.
Conclusions: A combination of remifentanil and midazolam provided satisfactory sedation for these patients. Owing to enhanced clearance rates, smaller (younger) children will require higher remifentanil infusion rates than larger (older) children and adults to achieve equivalent blood concentrations.
Revisão de Bolqueio cervical p/ endarterectomia carotidea
Title Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications+.[Review]
Source BJA: British Journal of Anaesthesia. 99(2):159-169, August 2007.
Abstract Carotid endarterectomy is commonly conducted under regional (deep, superficial, intermediate, or combined) cervical plexus block, but it is not known if complication rates differ. We conducted a systematic review of published papers to assess the complication rate associated with superficial (or intermediate) and deep (or combined deep plus superficial/intermediate). The null hypothesis was that complication rates were equal. Complications of interest were: (1) serious complications related to the placement of block, (2) incidence of conversion to general anaesthesia, and (3) serious systemic complications of the surgical-anaesthetic process. We retrieved 69 papers describing a total of 7558 deep/combined blocks and 2533 superficial/intermediate blocks. Deep/combined block was associated with a higher serious complication rate related to the injecting needle when compared with the superficial/intermediate block (odds ratio 2.13, P=0.006). The conversion rate to general anaesthesia was also higher with deep/combined block (odds ratio 5.15, P < 0.0001), but there was an equivalent incidence of other systemic serious complications (odds ratio 1.13, P=0.273; NS). We conclude that superficial/intermediate block is safer than any method that employs a deep injection. The higher rate of conversion to general anaesthesia with the deep/combined block may have been influenced by the higher incidence of direct complications, but may also suggest that the superficial/combined block provides better analgesia during surgery.
Source BJA: British Journal of Anaesthesia. 99(2):159-169, August 2007.
Abstract Carotid endarterectomy is commonly conducted under regional (deep, superficial, intermediate, or combined) cervical plexus block, but it is not known if complication rates differ. We conducted a systematic review of published papers to assess the complication rate associated with superficial (or intermediate) and deep (or combined deep plus superficial/intermediate). The null hypothesis was that complication rates were equal. Complications of interest were: (1) serious complications related to the placement of block, (2) incidence of conversion to general anaesthesia, and (3) serious systemic complications of the surgical-anaesthetic process. We retrieved 69 papers describing a total of 7558 deep/combined blocks and 2533 superficial/intermediate blocks. Deep/combined block was associated with a higher serious complication rate related to the injecting needle when compared with the superficial/intermediate block (odds ratio 2.13, P=0.006). The conversion rate to general anaesthesia was also higher with deep/combined block (odds ratio 5.15, P < 0.0001), but there was an equivalent incidence of other systemic serious complications (odds ratio 1.13, P=0.273; NS). We conclude that superficial/intermediate block is safer than any method that employs a deep injection. The higher rate of conversion to general anaesthesia with the deep/combined block may have been influenced by the higher incidence of direct complications, but may also suggest that the superficial/combined block provides better analgesia during surgery.
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