Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2004
Multicenter Study Comparative StudyAdverse gastrointestinal complications after cardiopulmonary bypass: can outcome be predicted from preoperative risk factors?
Adverse gastrointestinal (GI) outcome after cardiac surgery is an infrequent event but is a clinically important health care problem because of associated increased morbidity and mortality. The ability to identify patients at greatest risk before surgery may be helpful in planning appropriate perioperative management strategies. We examined the pre- and intraoperative characteristics of 2417 patients from 24 diverse United States medical centers enrolled in the Multicenter Study of Perioperative Ischemia Study who were undergoing cardiac surgery using cardiopulmonary bypass as predictors for adverse GI outcome. Resource utilization was evaluated for patients with and without adverse GI outcomes. Adverse GI outcomes occurred in 5.5% of patients (133 of 2417), increased in-hospital mortality 6.5-fold, prolonged the mean intensive care unit length of stay by 1 wk, and more than doubled the mean postoperative hospital stay (P < 0.0001). Predictors of adverse GI outcome included decreased left ventricular function, hyperbilirubinemia, thrombocytopenia, prolonged partial thromboplastin time, prior cardiovascular surgery, combined coronary artery bypass graft surgery and intracardiac or proximal aortic surgery, pharmacological cardiovascular support, and intraoperative transfusion. The literature suggests that adverse GI outcome after cardiac surgery is secondary to poor splanchnic perfusion, which many of these risk factors may predict. Therefore, patients deemed to be at risk before surgery may benefit from tightly controlled hemodynamic management and other strategies that optimize perioperative organ perfusion. ⋯ We identified the preoperative and intraoperative predictors associated with an increased incidence of postoperative gastrointestinal complications after cardiac surgery using cardiopulmonary bypass. Because these complications are associated with frequent morbidity and mortality, these predictors may be helpful in identifying patients at increased risk so that risk stratification can be modified and perioperative management can be appropriately adjusted.
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Anesthesia and analgesia · Jun 2004
ReviewThe use of intrathecal midazolam in humans: a case study of process.
Early preclinical work demonstrated the potential role of spinal benzodiazepine pharmacology in regulating spinal nociceptive transmission. We review this preclinical activity and the evolving implementation of intrathecal midazolam in humans for pain management. Important elements in this development for use in humans are issues pertinent to safety and the preclinical reports that have increased our understanding of intrathecal midazolam toxicity. We seek to emphasize the time course of these studies and how they merged to provide enabling data that drove the clinical implementation. In the case of midazolam, we point to the potential issues that arose when preclinical safety data were unreasonably ignored and how consideration of preclinical safety data can serve to facilitate drug development by demonstrating reasonable safety profiles that document the minimal degree of potential risk to the patient. Issues that are of continuing relevance to the use of intrathecal midazolam, including issues of formulation and kinetics, are considered. ⋯ The intrathecal use of midazolam has evolved over 20 years though a combination of preclinical and clinical investigations. We review the time course of this development to define critical elements that should be pursued in reducing the risk associated with the clinical use of a novel spinal drug.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe neuromuscular effects and tracheal intubation conditions after small doses of succinylcholine.
Succinylcholine 1.0 mg/kg usually produces excellent tracheal intubation conditions in 60 s. Recovery of respiratory muscle function after this dose, however, is not fast enough to forestall oxyhemoglobin desaturation when ventilation cannot be assisted. In this study, we investigated whether smaller doses of succinylcholine can produce satisfactory intubation conditions fast enough to allow rapid sequence induction with a shorter recovery time. Anesthesia was induced with fentanyl/propofol and maintained by propofol infusion and N(2)O in O(2). After the induction, 115 patients were randomly allocated to five groups according to the dose of succinylcholine (0.3 mg/kg, 0.4 mg/kg, 0.5 mg/kg, 0.6 mg/kg, or 1.0 mg/kg). Evoked adductor pollicis responses to continuous 1-Hz supramaximal ulnar nerve stimulation were recorded using acceleromyography. Tracheal intubation conditions were graded 60 s after succinylcholine administration. Onset time, maximal twitch depression, time to initial twitch detection after paralysis, and to 10%, 25%, 50%, and 90% twitch height recovery were recorded. Time to initial diaphragmatic movement as well as time to resumption of regular spontaneous respiratory movements were calculated. Onset times ranged between 82 s and 52 s, decreasing with increasing doses of succinylcholine but not differing between 0.6 and 1 mg/kg. Maximum twitch depression was similar after 0.5, 0.6, and 1 mg/kg (98.2%-100%). Recoveries of twitch height and apnea time were dose-dependent. Intubation conditions were often unacceptable after 0.3- and 0.4-mg/kg doses. Acceptable intubation conditions were achieved in all patients receiving a 0.5, 0.6, and 1 mg/kg dose of succinylcholine. Intubation conditions in patients receiving 0.6 and 1 mg/kg were identical, whereas times to T(1) = 50% and 90% and time to regular spontaneous reservoir bag movements were significantly shorter in the 0.6-mg/kg dose group (5.78, 7.25, and 4.0 min, respectively) versus patients receiving 1 mg/kg (8.55, 10.54, and 6.16 min, respectively). The use of 0.5 to 0.6 mg/kg of succinylcholine can produce acceptable intubation conditions 60 s after administration. The conditions achieved after 0.6 mg/kg are similar to those after 1.0 mg/kg. These smaller doses are associated with faster twitch recovery and shorter apnea time. ⋯ In normal healthy patients, succinylcholine 0.6 mg/kg produces clinical intubation conditions identical to the traditional 1.0-mg/kg dose but is associated with a shorter recovery time.
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Anesthesia and analgesia · Jun 2004
Comparative StudyIntrathecal midazolam I: a cohort study investigating safety.
Despite conflicting evidence regarding the safety of intrathecal midazolam from animal investigations, its clinical use is increasing. We investigated the potential of intrathecal midazolam to produce symptomatology suggestive of neurological damage. This study compared two cohorts of patients who received intrathecal anesthesia with or without intrathecal midazolam (2 mg). Eighteen risk factors were evaluated with respect to symptoms representing potential neurological complications. The definitions of these symptoms were made wide to maximize the chance of counting patients with neurological sequelae after intrathecal injections. Eleven-hundred patients were followed up prospectively during the first postoperative week by a hospital chart review and 1 mo later by a mailed questionnaire. Symptoms suggestive of neurological impairment, including motor or sensory changes and bladder or bowel dysfunction, were investigated. Intrathecal midazolam was not associated with an increased risk of neurologic symptoms. In contrast, neurologic symptoms were found to be increased by age >70 yr (relative risk, 8.72) and the occurrence of a blood-stained spinal tap (relative risk, 8.07). The administration of intrathecal midazolam, 2 mg, did not increase the occurrence of neurologic or urologic symptoms, as suggested by some preclinical animal experimentation. ⋯ Intrathecal midazolam provides segmental analgesia, but conflicting animal studies have cast doubts on its safety. This investigation studied the effect of intrathecal midazolam by observing two cohorts of patients. In clinical practice, intrathecal midazolam (2 mg) did not increase adverse neurological symptoms compared with conventional therapies.
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Anesthesia and analgesia · Jun 2004
Comparative StudyHeparinase-modified thrombelastography in term and preterm neonates.
Thrombelastography (TEG) appears to be a promising test to assess coagulation in infants and children. TEG enables a rapid assessment of hemostatic function with only 300 microL of whole blood and provides information about plasmatic coagulation, platelet function, and fibrinolysis. In this study, we used TEG to assess the coagulation system of preterm and term neonates to determine the effects of their deficient coagulation factor levels on global hemostatic function. Heparinase-modified TEG, platelet and red blood cell count, plasma fibrinogen, and prothrombin time were assessed in four groups of clinically stable infants: severely preterm (gestational age [GA], 27-31 wk), moderately preterm (GA, 32-36 wk), term (GA, 36-40 wk), and former preterm (corrected GA, 34-40 wk). Healthy adult volunteers served as a control group. When compared with the adult group, thromboelastography revealed no defects in coagulation from groups of clinically stable infants, documenting the functional integrity of coagulation despite, in part, decreased conventional coagulation variables. Because clinically stable preterm and term infants show a relatively small incidence of bleeding, despite prolonged conventional coagulation tests, TEG may better reflect the hemostatic potential of these patients compared with conventional coagulation tests. ⋯ This study assessed the coagulation of preterm and term infants by thrombelastography and found functional integrity of coagulation despite, in part, decreased conventional coagulation variables.