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 One patient was withdrawn from the study due to hypotension.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.
sábado, 25 de agosto de 2007
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.
ETE e embolia- Revisão
Title Transesophageal Echocardiography and Cardiovascular Sources of Embolism: Implications for Perioperative Management.[Review]
Source Anesthesiology. 107(2):333-346, August 2007.
Abstract Transesophageal echocardiography has become an invaluable investigation in patients with cardioembolic events because of its high sensitivity and specificity for defining detailed structure and function of the cardiovascular system. Patients who receive anesthesia and critical care may be at risk of systemic embolism from various cardiovascular sources. The main factors associated with embolism include intracardiac lesions such as thrombi, vegetations, and tumors; cardiac anomalies; and vascular disease, e.g., aortic atheroma. In this review article, the authors describe how transesophageal echocardiography may be used to identify various cardiovascular sources of embolism, provide risk stratification, influence medical therapy, and refine clinical decision making in patients receiving critical care and anesthesia. With these improvements, it is hoped that better patient outcomes may be achieved in the perioperative period.
Source Anesthesiology. 107(2):333-346, August 2007.
Abstract Transesophageal echocardiography has become an invaluable investigation in patients with cardioembolic events because of its high sensitivity and specificity for defining detailed structure and function of the cardiovascular system. Patients who receive anesthesia and critical care may be at risk of systemic embolism from various cardiovascular sources. The main factors associated with embolism include intracardiac lesions such as thrombi, vegetations, and tumors; cardiac anomalies; and vascular disease, e.g., aortic atheroma. In this review article, the authors describe how transesophageal echocardiography may be used to identify various cardiovascular sources of embolism, provide risk stratification, influence medical therapy, and refine clinical decision making in patients receiving critical care and anesthesia. With these improvements, it is hoped that better patient outcomes may be achieved in the perioperative period.
Procalcitonina x infecção
Title Assessment of the Accuracy of Procalcitonin to Diagnose Postoperative Infection after Cardiac Surgery.[Article]
Source Anesthesiology. 107(2):232-238, August 2007.
Abstract Background: Cardiopulmonary bypass induces a nonspecific inflammatory response. Procalcitonin has been advocated as a specific biomarker for infection. The authors studied the accuracy of procalcitonin to diagnose postoperative infection after cardiac surgery and compared it with those of C-reactive protein, white blood cell count, and interleukins 6 and 8.
Methods: The authors prospectively included 100 patients scheduled to undergo elective cardiac procedures with cardiopulmonary bypass. Blood samples were taken before surgery and each day over the 7-day postoperative period, and measurement of procalcitonin, C-reactive protein, white blood cell count, and interleukins 6 and 8 were performed. Diagnosis of infection was performed by a blinded expert panel. Data are expressed as value [95% confidence interval].
Results: Infection was diagnosed in 16 patients. Procalcitonin was significantly higher in infected patients, with a peak reached on the third postoperative day. Only the areas under the receiver operating curve of procalcitonin (0.88 [0.71-0.95]) and C-reactive protein (0.72 [0.58-0.82]) were significantly different from the no-discrimination curve, and that of procalcitonin was significantly different from those of C-reactive protein, white blood cell count, and interleukins 6 and 8. A procalcitonin value greater than 1.5 ng/ml beyond the second day diagnosed postoperative infection with a sensitivity of 0.93 [0.70-0.99] and a specificity of 0.80 [0.70-0.87]. Procalcitonin was significantly higher in patients who died (27.5 [1.65-40.5] vs. 1.2 [0.7-1.5] ng/ml; P < 0.001).
Conclusion: Procalcitonin is a valuable marker of bacterial infections after cardiac surgery.
Source Anesthesiology. 107(2):232-238, August 2007.
Abstract Background: Cardiopulmonary bypass induces a nonspecific inflammatory response. Procalcitonin has been advocated as a specific biomarker for infection. The authors studied the accuracy of procalcitonin to diagnose postoperative infection after cardiac surgery and compared it with those of C-reactive protein, white blood cell count, and interleukins 6 and 8.
Methods: The authors prospectively included 100 patients scheduled to undergo elective cardiac procedures with cardiopulmonary bypass. Blood samples were taken before surgery and each day over the 7-day postoperative period, and measurement of procalcitonin, C-reactive protein, white blood cell count, and interleukins 6 and 8 were performed. Diagnosis of infection was performed by a blinded expert panel. Data are expressed as value [95% confidence interval].
Results: Infection was diagnosed in 16 patients. Procalcitonin was significantly higher in infected patients, with a peak reached on the third postoperative day. Only the areas under the receiver operating curve of procalcitonin (0.88 [0.71-0.95]) and C-reactive protein (0.72 [0.58-0.82]) were significantly different from the no-discrimination curve, and that of procalcitonin was significantly different from those of C-reactive protein, white blood cell count, and interleukins 6 and 8. A procalcitonin value greater than 1.5 ng/ml beyond the second day diagnosed postoperative infection with a sensitivity of 0.93 [0.70-0.99] and a specificity of 0.80 [0.70-0.87]. Procalcitonin was significantly higher in patients who died (27.5 [1.65-40.5] vs. 1.2 [0.7-1.5] ng/ml; P < 0.001).
Conclusion: Procalcitonin is a valuable marker of bacterial infections after cardiac surgery.
DC em cirurgia cardiaca- comparação de metodos
Title An evaluation of cardiac output by five arterial pulse contour techniques during cardiac surgery.[Article]
Source Anaesthesia. 62(8):760-768, August 2007.
Abstract Summary: The bias, precision and tracking ability of five different pulse contour methods were evaluated by simultaneous comparison of cardiac output values from the conventional thermodilution technique (COtd). The five different pulse contour methods included in this study were: Wesseling's method (cZ); the Modelflow method; the LiDCO system; the PiCCO system and a recently developed Hemac method. We studied 24 cardiac surgery patients undergoing uncomplicated coronary artery bypass grafting. In each patient, the first series of COtd was used to calibrate the five pulse contour methods. In all, 199 series of measurements were accepted by all methods and included in the study. COtd ranged from 2.14 to 7.55 l.min-1, with a mean of 4.81 l.min-1. Bland-Altman analysis showed the following bias and limits of agreement: cZ, 0.23 and - 0.80 to 1.26 l.min-1; Modelflow, 0.00 and - 0.74 to 0.74 l.min-1; LiDCO, - 0.17 and - 1.55 to 1.20 l.min-1; PiCCO, 0.14 and - 1.60 to 1.89 l.min-1; and Hemac, 0.06 and - 0.81 to 0.93 l.min-1. Changes in cardiac output larger than 0.5 l.min-1 (10%) were correctly followed by the Modelflow and the Hemac method in 96% of cases. In this group of subjects, without congestive heart failure, with normal heart rhythm and reasonable peripheral circulation, the best results in absolute values as well as in tracking changes in cardiac output were measured using the Modelflow and Hemac pulse contour methods, based on non-linear three-element Windkessel models.
Source Anaesthesia. 62(8):760-768, August 2007.
Abstract Summary: The bias, precision and tracking ability of five different pulse contour methods were evaluated by simultaneous comparison of cardiac output values from the conventional thermodilution technique (COtd). The five different pulse contour methods included in this study were: Wesseling's method (cZ); the Modelflow method; the LiDCO system; the PiCCO system and a recently developed Hemac method. We studied 24 cardiac surgery patients undergoing uncomplicated coronary artery bypass grafting. In each patient, the first series of COtd was used to calibrate the five pulse contour methods. In all, 199 series of measurements were accepted by all methods and included in the study. COtd ranged from 2.14 to 7.55 l.min-1, with a mean of 4.81 l.min-1. Bland-Altman analysis showed the following bias and limits of agreement: cZ, 0.23 and - 0.80 to 1.26 l.min-1; Modelflow, 0.00 and - 0.74 to 0.74 l.min-1; LiDCO, - 0.17 and - 1.55 to 1.20 l.min-1; PiCCO, 0.14 and - 1.60 to 1.89 l.min-1; and Hemac, 0.06 and - 0.81 to 0.93 l.min-1. Changes in cardiac output larger than 0.5 l.min-1 (10%) were correctly followed by the Modelflow and the Hemac method in 96% of cases. In this group of subjects, without congestive heart failure, with normal heart rhythm and reasonable peripheral circulation, the best results in absolute values as well as in tracking changes in cardiac output were measured using the Modelflow and Hemac pulse contour methods, based on non-linear three-element Windkessel models.
PCR em anestesia em cardiopatia congenita
The Frequency of Anesthesia-Related Cardiac Arrests in Patients with Congenital Heart Disease Undergoing Cardiac Surgery.[Miscellaneous]
Source Anesthesia & Analgesia. 105(2):335-343, August 2007.
Abstract BACKGROUND: The frequency of anesthesia-related cardiac arrests during pediatric anesthesia has been reported between 1.4 and 4.6 per 10,000 anesthetics. ASA physical status >III and younger age are risk factors. Patients with congenital cardiac disease may also be at increased risk. Therefore, in this study, we evaluated the frequency of cardiac arrest in patients with congenital heart disease undergoing cardiac surgery at a large pediatric tertiary referral center.
METHODS: Using an established data registry, all cardiac arrests from January 2000 through December 2005 occurring in the cardiac operating rooms were reviewed. A cardiac arrest was defined as any event requiring external or internal chest compressions, with or without direct cardioversion. Events determined to be anesthesia-related were classified as likely related or possibly related.
RESULTS: There were 41 cardiac arrests in 40 patients (median age, 2.9 mo; range, 2 days to 23 yr) during 5213 anesthetics over the time period, for an overall frequency of 0.79%; 78% were open procedures requiring cardiopulmonary bypass and 22% closed procedures not requiring cardiopulmonary bypass. Eleven cardiac arrests (26.8%) were classified as either likely (n = 6) or possibly related (n = 5) to anesthesia, (21.1 per 10,000 anesthetics) but with no mortality; 30 were categorized as procedure-related. The incidence of anesthesia-related and procedure-related cardiac arrests was highest in neonates (P < 0.001). There was no association with year of event or experience of the anesthesiologist.
CONCLUSION: The frequency of anesthesia-related cardiac arrest in patients undergoing cardiac surgery is increased, but is not associated with an increase in mortality. Neonates and infants are at higher risk. Careful preparation and anticipation is important to ensure timely and effective resuscitation.
Source Anesthesia & Analgesia. 105(2):335-343, August 2007.
Abstract BACKGROUND: The frequency of anesthesia-related cardiac arrests during pediatric anesthesia has been reported between 1.4 and 4.6 per 10,000 anesthetics. ASA physical status >III and younger age are risk factors. Patients with congenital cardiac disease may also be at increased risk. Therefore, in this study, we evaluated the frequency of cardiac arrest in patients with congenital heart disease undergoing cardiac surgery at a large pediatric tertiary referral center.
METHODS: Using an established data registry, all cardiac arrests from January 2000 through December 2005 occurring in the cardiac operating rooms were reviewed. A cardiac arrest was defined as any event requiring external or internal chest compressions, with or without direct cardioversion. Events determined to be anesthesia-related were classified as likely related or possibly related.
RESULTS: There were 41 cardiac arrests in 40 patients (median age, 2.9 mo; range, 2 days to 23 yr) during 5213 anesthetics over the time period, for an overall frequency of 0.79%; 78% were open procedures requiring cardiopulmonary bypass and 22% closed procedures not requiring cardiopulmonary bypass. Eleven cardiac arrests (26.8%) were classified as either likely (n = 6) or possibly related (n = 5) to anesthesia, (21.1 per 10,000 anesthetics) but with no mortality; 30 were categorized as procedure-related. The incidence of anesthesia-related and procedure-related cardiac arrests was highest in neonates (P < 0.001). There was no association with year of event or experience of the anesthesiologist.
CONCLUSION: The frequency of anesthesia-related cardiac arrest in patients undergoing cardiac surgery is increased, but is not associated with an increase in mortality. Neonates and infants are at higher risk. Careful preparation and anticipation is important to ensure timely and effective resuscitation.
terça-feira, 24 de julho de 2007
Staunching Hemorrhage
Staunching Hemorrhage
New England Journal of Medicine reviewers present information about aprotinin, tranexamic acid, EACA, desmopressin, and rFVIIa. New England Journal of Medicine reviewers present information about aprotinin, tranexamic acid, EACA, desmopressin, and rFVIIa.
C_REMARK -->
Uncontrollable bleeding is every physician’s and patient’s nightmare. Such bleeding can be due to disease, injury, surgery, or anticoagulant therapy and can arise from lesions in the brain, lung, liver, or gastrointestinal or genitourinary tract. Most clinicians’ initial responses are to transfuse blood, plasma, and platelets, but adjunctive pharmacologic therapy also is available. The efficacy and safety of some of these pharmaceutical agents were reviewed by two experts in blood coagulation. The agents considered were aprotinin, tranexamic acid, -aminocaproic acid (EACA), desmopressin, and recombinant factor VIIa (rFVIIa).
Aprotinin is a powerful protease inhibitor that is derived from bovine lung tissue; it limits clot dissolution or fibrinolysis and markedly diminishes blood loss and need for transfusion in patients undergoing coronary-artery bypass surgery. However, this activity comes at a price: In one study, aprotinin, compared with placebo, doubled the risk for severe renal failure and led to higher risk for myocardial infarction, heart failure, and stroke (N Engl J Med 2006; 354:353). Other studies have confirmed these results, so aprotinin is recommended mainly for patients who are undergoing complicated procedures with very high bleeding risk.
Tranexamic acid and EACA bind to lysine receptors on plasminogen, which inhibits its conversion to plasmin (the enzyme that lyses fibrin). Although both agents have exhibited clinical efficacy, tranexamic acid is more potent than EACA, and both are weaker than aprotinin. Nevertheless, they do appear to limit blood loss and the need for reoperation. Unfortunately, the safety of these drugs has not been established firmly; a large randomized trial of tranexamic acid in cardiac surgical patients is underway.
Desmopressin induces the release of large multimers of von Willebrand factor from storage organelles in endothelial cells; these multimers enhance platelet adhesion and aggregation. Although desmopressin is quite effective in most patients with von Willebrand disease and in some with mild hemophilia A, trials of desmopressin in cardiac surgery have shown only small decreases in perioperative blood loss. Adverse effects include hyponatremia due to water retention as well as occasional thrombotic events.
Recombinant FVIIa is a potent hemostatic agent that binds to activated platelets at the site of injury and enhances thrombin generation and clot formation. This agent curbs blood loss in a variety of clinical situations, ranging from radical prostatectomy to battlefield injuries. However, not all trials have produced positive results, and no randomized controlled clinical trials have been completed. Furthermore, the optimal dose of rFVIIa is unknown; doses from 20 µg/kg to 200 µg/kg have been used. Whether observed serious thrombotic events are dose-related has not been established. Guidelines for the use of rFVIIa, including indications for treatment and identification of patients in whom treatment should be avoided because of high risk for thrombosis, are needed urgently.
— David Green, MD, PhD
Published in Journal Watch Oncology and Hematology May 30, 2007
Citation(s):
Mannucci PM and Levi M. Prevention and treatment of major blood loss. N Engl J Med 2007 May 31; 356:2301-11.
Original article (Subscription may be required)
Medline abstract (Free)
New England Journal of Medicine reviewers present information about aprotinin, tranexamic acid, EACA, desmopressin, and rFVIIa. New England Journal of Medicine reviewers present information about aprotinin, tranexamic acid, EACA, desmopressin, and rFVIIa.
C_REMARK -->
Uncontrollable bleeding is every physician’s and patient’s nightmare. Such bleeding can be due to disease, injury, surgery, or anticoagulant therapy and can arise from lesions in the brain, lung, liver, or gastrointestinal or genitourinary tract. Most clinicians’ initial responses are to transfuse blood, plasma, and platelets, but adjunctive pharmacologic therapy also is available. The efficacy and safety of some of these pharmaceutical agents were reviewed by two experts in blood coagulation. The agents considered were aprotinin, tranexamic acid, -aminocaproic acid (EACA), desmopressin, and recombinant factor VIIa (rFVIIa).
Aprotinin is a powerful protease inhibitor that is derived from bovine lung tissue; it limits clot dissolution or fibrinolysis and markedly diminishes blood loss and need for transfusion in patients undergoing coronary-artery bypass surgery. However, this activity comes at a price: In one study, aprotinin, compared with placebo, doubled the risk for severe renal failure and led to higher risk for myocardial infarction, heart failure, and stroke (N Engl J Med 2006; 354:353). Other studies have confirmed these results, so aprotinin is recommended mainly for patients who are undergoing complicated procedures with very high bleeding risk.
Tranexamic acid and EACA bind to lysine receptors on plasminogen, which inhibits its conversion to plasmin (the enzyme that lyses fibrin). Although both agents have exhibited clinical efficacy, tranexamic acid is more potent than EACA, and both are weaker than aprotinin. Nevertheless, they do appear to limit blood loss and the need for reoperation. Unfortunately, the safety of these drugs has not been established firmly; a large randomized trial of tranexamic acid in cardiac surgical patients is underway.
Desmopressin induces the release of large multimers of von Willebrand factor from storage organelles in endothelial cells; these multimers enhance platelet adhesion and aggregation. Although desmopressin is quite effective in most patients with von Willebrand disease and in some with mild hemophilia A, trials of desmopressin in cardiac surgery have shown only small decreases in perioperative blood loss. Adverse effects include hyponatremia due to water retention as well as occasional thrombotic events.
Recombinant FVIIa is a potent hemostatic agent that binds to activated platelets at the site of injury and enhances thrombin generation and clot formation. This agent curbs blood loss in a variety of clinical situations, ranging from radical prostatectomy to battlefield injuries. However, not all trials have produced positive results, and no randomized controlled clinical trials have been completed. Furthermore, the optimal dose of rFVIIa is unknown; doses from 20 µg/kg to 200 µg/kg have been used. Whether observed serious thrombotic events are dose-related has not been established. Guidelines for the use of rFVIIa, including indications for treatment and identification of patients in whom treatment should be avoided because of high risk for thrombosis, are needed urgently.
— David Green, MD, PhD
Published in Journal Watch Oncology and Hematology May 30, 2007
Citation(s):
Mannucci PM and Levi M. Prevention and treatment of major blood loss. N Engl J Med 2007 May 31; 356:2301-11.
Original article (Subscription may be required)
Medline abstract (Free)
Assinar:
Postagens (Atom)
Postagens
