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Spinal cord protection during aortic occlusion: Efficacy of intrathecal tetracaine
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116 LITERATURE REVIEW Schultz JD, Stamler J, Loscalzo J: Intravenous nitroglycerin infusion inhibits cyclic blood flow re- sponses caused by periodic platelet thrombus forma- tion in stenosed canine coronary arteries. Circulation 83:2122-2127,199l Nitroglycerin, known to inhibit platelet aggregation in vitro, was administered to a canine model of coronary artery stenosis associ- ated with cyclic reductions in coronary blood flow caused by periodic platelet thrombus formation. The frequency of reduced coronary flow cycles, measured by electromagnetic flow probe, was significantly reduced by the administration of nitroglycerin, 10 to 15 &kg/min, without a significant change in baseline coronary artery blood flow. The relative contribution of this antiplatelet effect of nitroglycerin used in clinical doses in humans is unknown. Agee JM, Flanagan T, Blackbourne LH, et al: Reducing postischemic paraplegia using conjugated superoxide dismutase. Ann Thorac Surg 51:911-915, 1991 Thirty rabbits underwent 40 minutes of aortic occlusion. Polyeth- ylene glycol-conjugated superoxide dismutase (PEG-SOD), 85,000 U/kg, 24 hours before occlusion, 10,000 U/kg before and subse- quent to spinal ischemia, and superoxide dismutase in the same dose or placebo were administered in this model of paraplegia. At 96 hours after occlusion, the degree of neurological injury was ameliorated in the PEG-SOD-treated animals. None of the control or superoxide dismutase animals had a normal neurological exami- nation. Conjugation of superoxide dismutase with PEG-SOD increases circulatory half-life and may facilitate intracellular access of this free radical scavenger. Breckwoldt WL, Genco CM, Connelly RJ, et al: Spinal cord protection during aortic occlusion: Effi- cacy of intrathecal tetracaine. Ann Thorac Surg, 51:959-963,199l In this experimental study, six groups of rabbits were random- ized to control, intrathecal tetracaine, intrathecal saline, or intrave- nous thiopental groups before 25 or 30 minutes of aortic occlusion. Animals pretreated with intrathecal tetracaine showed signifi- cantly better preservation of neurological function than controls and saline-treated rabbits. Intravenous thiopental had no benefi- cial effect. The protective drug effect may result from suppression of cellular metabolism or stabilization of the neuronal cell mem- brane. Swain JA, McDonald TJ, Griffith PK, et al: Low flow hypothermic cardiopulmonary bypass protects the brain. J Thorac Cardiovasc Surg 102:76-M, 1991 In vivo phosphorus-31 nuclear magnetic resonance spectroscopy was used to measure high-energy phosphate concentration and intracellular pH in sheeps’ brains during four methods of cerebral protection. The animals were cooled to WC, then managed with either circulatory arrest or continuous low-flow cardioplegia at flow rates of 5 mL/kg/min or 10 mL/kg/min for 2 hours. Both circulatory arrest and a 5 mL/kg/min flow rate resulted in severe intracellular acidosis and depletion of high-energy phosphates. The flow rate of 10 mlikglmin preserved the nuclear magnetic resonance parameters. The fourth group of sheep underwent 1 hour of circulatory arrest, full-flow systemic reperfusion for 30 minutes, then 1 hour of circulatory arrest. Less cerebral protection was offered than was achieved during continuous low-flow bypass at 10 mllkgimin. Siu SC, Kowalchuk GJ, Welty FK, et al: Intraortic balloon counterpulsation support in the high risk cardiac patient undergoing urgent non-cardiac sur- gery. Chest 99:1342-1345,199l This small clinical series demonstrated that intraortic balloon counterpulsation may be used together with invasive hemodynamic monitoring to reduce the incidence of perioperative cardiac events. In eight patients with unstable coronary syndromes or severe coronary disease undergoing urgent noncardiac surgery, there were no perioperative cardiac events while the balloon pump was in place. However, two postoperative cardiac events occurred in the first week after balloon removal and one patient required urgent femoral thrombectomy. This uncontrolled series does not permit conclusion that this modality alters surgical outcome. Esposito TJ, Jurkovich GJ, Rice CL, et al: Reap- praisal of emergency room thoracotomy in a changing environment. J Trauma 31:881-887,199l The outcome of 112 patients with penetrating or blunt injury undergoing emergency room thoracotomy was retrospectively stud- ied. Overall survival was 1.8%, 4.2% in victims of penetrating injury, and 1.1% following blunt trauma. No survival occurred in patients with cardiopulmonary resuscitation initiated at the scene or arriving at the hospital with idioventricular rhythm or asystole. Survival was slightly higher in patients in normal sinus rhythm or ventricular fibrillation on arrival. Survival was greatest (11.8%) in patients with blood pressure and spontaneous respirations in the field. Liberal performance of emergency room thoracotomy is associated with poor results and a greater potential for risk of exposure to medical personnel. Emergency room thoracotomy is justified only when vital signs or a cardiac rhythm deteriorate shortly before thoracotomy. Konduri GG, Woodward LL: Selective pulmonary vasodilation by low-dose infusion of adenosine triphos- phate in newborn lambs. J Pediatr 119:94-102,199l The effects of adenosine triphosphate (ATP) administration on systemic and pulmonary hemodynamics were observed in a three- day-old instrumented lamb model. ATP, in doses from 0.01 to 2.5 uM/kglmin, or placebo, were infused into the right atria1 line during normoxia or hypoxemia (alveolar PO,. 10%). Significant decreases in pulmonary vascular resistance were observed to doses ~0.08 uM/kg/min during normoxia and to all doses during hypoxemia. Significant reductions in systemic vascular resistance were observed with ATP doses >0.3 uikgimin. The authors conclude the drug’s effects are specific for the pulmonary circula- tion at doses 10.15 uM/kg/min. Because ATP is rapidly metabo- lized by vascular endothelium, right atrial infusion permits first pass through the pulmonary circulation producing specific pulmo- nary vasodilation. Trittel DL, Wiest DB, Gillette PC: Cardiovascular antiarrhythmic effects of esmoloi in children. J Pedi- atr 119:142-147,199l In 20 children, aged 2 to 16 years during diagnostic electrophysi- ologic studies, esmolol infusion was titrated to a 10% reduction in
Transcript of Spinal cord protection during aortic occlusion: Efficacy of intrathecal tetracaine
116 LITERATURE REVIEW
Schultz JD, Stamler J, Loscalzo J: Intravenous nitroglycerin infusion inhibits cyclic blood flow re- sponses caused by periodic platelet thrombus forma- tion in stenosed canine coronary arteries. Circulation 83:2122-2127,199l
Nitroglycerin, known to inhibit platelet aggregation in vitro, was administered to a canine model of coronary artery stenosis associ- ated with cyclic reductions in coronary blood flow caused by periodic platelet thrombus formation. The frequency of reduced coronary flow cycles, measured by electromagnetic flow probe, was significantly reduced by the administration of nitroglycerin, 10 to 15 &kg/min, without a significant change in baseline coronary artery blood flow. The relative contribution of this antiplatelet effect of nitroglycerin used in clinical doses in humans is unknown.
Agee JM, Flanagan T, Blackbourne LH, et al: Reducing postischemic paraplegia using conjugated superoxide dismutase. Ann Thorac Surg 51:911-915, 1991
Thirty rabbits underwent 40 minutes of aortic occlusion. Polyeth- ylene glycol-conjugated superoxide dismutase (PEG-SOD), 85,000 U/kg, 24 hours before occlusion, 10,000 U/kg before and subse- quent to spinal ischemia, and superoxide dismutase in the same dose or placebo were administered in this model of paraplegia. At 96 hours after occlusion, the degree of neurological injury was ameliorated in the PEG-SOD-treated animals. None of the control or superoxide dismutase animals had a normal neurological exami- nation. Conjugation of superoxide dismutase with PEG-SOD increases circulatory half-life and may facilitate intracellular access of this free radical scavenger.
Breckwoldt WL, Genco CM, Connelly RJ, et al: Spinal cord protection during aortic occlusion: Effi- cacy of intrathecal tetracaine. Ann Thorac Surg, 51:959-963,199l
In this experimental study, six groups of rabbits were random- ized to control, intrathecal tetracaine, intrathecal saline, or intrave- nous thiopental groups before 25 or 30 minutes of aortic occlusion. Animals pretreated with intrathecal tetracaine showed signifi- cantly better preservation of neurological function than controls and saline-treated rabbits. Intravenous thiopental had no benefi- cial effect. The protective drug effect may result from suppression of cellular metabolism or stabilization of the neuronal cell mem- brane.
Swain JA, McDonald TJ, Griffith PK, et al: Low flow hypothermic cardiopulmonary bypass protects the brain. J Thorac Cardiovasc Surg 102:76-M, 1991
In vivo phosphorus-31 nuclear magnetic resonance spectroscopy was used to measure high-energy phosphate concentration and intracellular pH in sheeps’ brains during four methods of cerebral protection. The animals were cooled to WC, then managed with either circulatory arrest or continuous low-flow cardioplegia at flow rates of 5 mL/kg/min or 10 mL/kg/min for 2 hours. Both circulatory arrest and a 5 mL/kg/min flow rate resulted in severe intracellular acidosis and depletion of high-energy phosphates. The flow rate of 10 mlikglmin preserved the nuclear magnetic resonance parameters. The fourth group of sheep underwent 1 hour of circulatory arrest, full-flow systemic reperfusion for 30
minutes, then 1 hour of circulatory arrest. Less cerebral protection was offered than was achieved during continuous low-flow bypass at 10 mllkgimin.
Siu SC, Kowalchuk GJ, Welty FK, et al: Intraortic balloon counterpulsation support in the high risk cardiac patient undergoing urgent non-cardiac sur- gery. Chest 99:1342-1345,199l
This small clinical series demonstrated that intraortic balloon counterpulsation may be used together with invasive hemodynamic monitoring to reduce the incidence of perioperative cardiac events. In eight patients with unstable coronary syndromes or severe coronary disease undergoing urgent noncardiac surgery, there were no perioperative cardiac events while the balloon pump was in place. However, two postoperative cardiac events occurred in the first week after balloon removal and one patient required urgent femoral thrombectomy. This uncontrolled series does not permit conclusion that this modality alters surgical outcome.
Esposito TJ, Jurkovich GJ, Rice CL, et al: Reap- praisal of emergency room thoracotomy in a changing environment. J Trauma 31:881-887,199l
The outcome of 112 patients with penetrating or blunt injury undergoing emergency room thoracotomy was retrospectively stud- ied. Overall survival was 1.8%, 4.2% in victims of penetrating injury, and 1.1% following blunt trauma. No survival occurred in patients with cardiopulmonary resuscitation initiated at the scene or arriving at the hospital with idioventricular rhythm or asystole. Survival was slightly higher in patients in normal sinus rhythm or ventricular fibrillation on arrival. Survival was greatest (11.8%) in patients with blood pressure and spontaneous respirations in the field. Liberal performance of emergency room thoracotomy is associated with poor results and a greater potential for risk of exposure to medical personnel. Emergency room thoracotomy is justified only when vital signs or a cardiac rhythm deteriorate shortly before thoracotomy.
Konduri GG, Woodward LL: Selective pulmonary vasodilation by low-dose infusion of adenosine triphos- phate in newborn lambs. J Pediatr 119:94-102,199l
The effects of adenosine triphosphate (ATP) administration on systemic and pulmonary hemodynamics were observed in a three- day-old instrumented lamb model. ATP, in doses from 0.01 to 2.5 uM/kglmin, or placebo, were infused into the right atria1 line during normoxia or hypoxemia (alveolar PO,. 10%). Significant decreases in pulmonary vascular resistance were observed to doses ~0.08 uM/kg/min during normoxia and to all doses during hypoxemia. Significant reductions in systemic vascular resistance were observed with ATP doses >0.3 uikgimin. The authors conclude the drug’s effects are specific for the pulmonary circula- tion at doses 10.15 uM/kg/min. Because ATP is rapidly metabo- lized by vascular endothelium, right atrial infusion permits first pass through the pulmonary circulation producing specific pulmo- nary vasodilation.
Trittel DL, Wiest DB, Gillette PC: Cardiovascular antiarrhythmic effects of esmoloi in children. J Pedi- atr 119:142-147,199l
In 20 children, aged 2 to 16 years during diagnostic electrophysi- ologic studies, esmolol infusion was titrated to a 10% reduction in
