Maintenance Of Hemodynamic Stability Research Articles

An Intraoperative Fluid Therapy Fuzzy Logic Control System for Renal Transplantation

The number of kidney transplants has increased sharply in recent years mainly due to addition of pathologic cases, (e.g. patient with type diabetes II, advanced cardiomyopathy, various forms of vasculitis, sickle cell disease and morbid obesity) which were considered as high risk group, to regular renal transplantation (RT) operations. However, it is still a fact that many patients undergoing RT operations have a higher chance of getting intraoperative complication than regular patient group. As a result, anesthesiologists load was increased significantly in RT operations. Maximal hydration during RT is of utmost importance. The most important intraoperative measure that improves the likelihood of immediate graft function is to maintain an adequate intravascular volume and ensure satisfactory perfusion of the transplanted kidney. Intravascular volume is a crucial factor in the maintenance of hemodynamic stability, tissue oxygenation and organ function. Crystalloid solutions are the first choice to correct fluid and electrolyte deficits in these patients. However, in case of major hypovolemia, particularly in situations of increased capillary permeability, colloid solutions are indicated to achieve sufficient tissue perfusion. Because of the fluid abnormalities usually found in patients with renal failure, the high incidence of cardiac disease and the importance of graft perfusion and early function, central venous pressure (CVP) monitoring is recommended. A CVP of 10–15 mm Hg has been recommended to maintain optimal intravascular volume. To lower the risk for acute tubular necrosis and transplant failure caused by hypovolemia. In this study, a fuzzy logic system is used to control fluid balance during RT by changes in blood pressure, heart rate and CVP value. Currently, the administration of intravascular volume is carried out primarily based on the experience and expertise of the anesthesiologist as there is no analytical method available to estimate the transplant patient's fluid level. To increase kidney viability in transplant surgery, patient safety and comfort during RT is one of the most important potential benefits of the system. For this project, A total of 30 kidney transplantation operations performed in Akdeniz University Organ Transplantation Center were followed and all physiological data recorded during the last year. This data base is used for contribution of the fuzzy system membership functions and to determine base variable intervals. Also the developed system was tested with these operations records.

Hypertension artérielle et anesthésie

Hypertension is one of the most important risk factors for cerebrovascular disease and ischaemic heart disease. Postoperative adverse outcomes of hypertension include cardiac death, left ventricular hypertrophy (with impaired diastolic function) leading to ventricular failure, myocardial ischaemia and infarction, renal damage and cerebrovascular accidents. The role of the anaesthetist for patients suffering from chronic hypertension goes beyond that in most other patient population since there is a unique opportunity to improve long-term survival and function by applying adequate preoperative evaluation and refined perioperative anaesthetic management. Maintenance of hemodynamic stability throughout the perioperative period is essential in these patients with cardiovascular risk, most of whom benefit from cardiac treatments designed to improve both their symptoms and life expectancy. Anesthetic agents development and improved delivery have reduced the importance of direct anaesthetic effects on heart versus effects of interactions with other cardio-vascular drugs. In patients with hypertensive disease undergoing anaesthesia and surgery, disease-drug-anaesthesia interaction may either increase or reduce the likelihood of perioperative morbidity and mortality. The blockade of the sympathetic system is well tolerated and has several beneficial effects including the prevention of hypertensive episodes and myocardial ischemia. By contrast, the blockade of the renin-angiotensin system markedly increases the lowering blood pressure effect of anesthesia. This is not surprising if one takes into account that this system is activated by any decrease in the loading conditions of the heart, especially preload. That leads to withdraw treatments, which interfere with the renin angiotensin system, the eve of surgery. Better knowledge of the physiopathological mechanisms involved in postoperative complications now enables to define perioperative managements for hypertensive patients undergoing non cardiac surgery and thus limit the risk of anesthesia. The main goal of the perioperative management is to limit postoperative stress by adequate intra and postoperative management and to control postoperatively increased sympathetic tone or its circulatory effects by administering preventive cardiovascular medications which interfere with the sympathic system. The prevention of intraoperative hypothermia and intensive postoperative analgesia significantly limit circulatory stress in the postoperative period. However, although diminished, these contraints have not been abolished. This is the reason why many authors have envisaged the administration of cardiovascular medication to effectively limit the sympathetic stimulation which persists several days after surgery. Two types of cardiovascular drugs have been recommended : beta-adrenergic blocking drugs and alpha-2 adrenoreceptor agonists. Postoperative hypertension episodes must be treated by vasodilatators (calcium channel blockers) and/or betablockers.

Maintenance of hemodynamic stability during pericardiectomy with the Starfish 2 Heart Positioner

Pericardiectomy for chronic pericarditis can be a technically difficult procedure associated with high mortality. 1 The use of cardiopulmonary bypass (CPB), although necessary on occasion, can be associated with significant bleeding, leading many surgeons to prefer its avoidance. Technologic advances in heart positioning devices have enabled the widespread application of beating-heart coronary revascularization. In this report we describe our use of the Starfish 2 Heart Positioner (Medtronic, Inc, Minneapolis, Minn) in the treatment of chronic pericarditis. Clinical Summaries PATIENT 1. A 41-year-old Iranian war veteran had a severalweek history of progressive shortness of breath, increasing abdominal girth, and peripheral edema. Echocardiography and computed tomography confirmed the diagnosis of severe constrictive pericarditis. Subsequent cardiac catheterization demonstrated the typical dip and plateau pattern. At the operation, the heart was approached through a median sternotomy with a Cell Saver system (Haemonetics Corporation, Braintree Mass) available and CPB on standby. The thickened (7 mm), calcified parietal pericardium was resected laterally toward each phrenic nerve. Once the visceral pericardium at the apex of the left ventricle was exposed, the Starfish 2 Heart Positioner was applied in the standard position used for off-pump coronary artery bypass grafting (OPCAB; Figure 1). With the Starfish retractor, the remaining parietal pericardium was resected from phrenic to phrenic nerve, including its diaphragmatic surface. In addition, the visceral pericardium (5 mm in thickness) was resected in its entirety, except for a small portion along both the left anterior descending coronary artery and posterior left atrium. The patient remained in hemodynamically stable condition throughout the case without inotropic or vasopressor support, and no blood transfusions were needed. He was extubated 5 hours after the operation and discharged from the hospital on postoperative day 6. Pathologic examination revealed nonspecific fibrous pericarditis with calcification. PATIENT 2. A 29-year-old man had chronic chest pain after an episode of pneumonia that was diagnosed as pericarditis. His pain was refractory to nonsteroidal anti-inflammatory agents, colchicine, and oral steroids. On referral to our service, he had class III New York Heart Association dyspnea. The diagnosis of pericarditis was confirmed on echocardiography and chest CT. This patient’ s heart was also approached through a median sternotomy with a Cell Saver system available and CPB on standby. The conduct of the operation and use of the Starfish 2 Heart Positioner were both similar to those in our first patient. The thick parietal pericardium (8 mm) was resected to both phrenic nerves and along the diaphragm. The 6-mm visceral pericardium was subsequently resected from all heart surfaces, except a small patch on the posterior left atrium. There was no need for inotropes or vasopressors, because the patient remained in hemodynamically stable condition throughout; in addition, no blood transfusions were needed. The patient was extubated 7 hours after the procedure and discharged from the hospital on postoperative day 4. Pathologic examination revealed chronic pericarditis with granulation tissue.

Immediate Extubation after Aortic Valve Surgery Using High Thoracic Epidural Anesthesia.

Abstract Purpose: Fast-track anesthesia has gained widespread use in cardiac centers around the world. No study has focused on immediate extubation after aortic valve surgery. This study examines the feasibility and hemodynamic stability of immediate extubation after simple or combined aortic valve surgery using thoracic epidural anesthesia. Methods: Thirty patients undergoing aortic valve surgery with an ejection fraction of more than 30% were included in this prospective audit. After insertion of a high thoracic epidural catheter, induction with fentanyl 2 to 4 microg/kg, administration of propofol 1 to 2 mg/kg, and endotracheal intubation facilitated by rocuronium, anesthesia was maintained with sevoflurane titrated according to bispectral index (target, 50). Perioperative analgesia was provided by high thoracic epidural analgesia (TEA) (bupivacaine 0.125% 6-14 mL/h). Hemodynamic data were compared by Friedman test. P <.05 was considered to show a significant difference. Data are presented as median (25th-75th percentile). Results: Patients underwent simple aortic valve surgery (n = 17) or combined aortic valve surgery (n = 13) with additional coronary artery bypass grafting (n = 8), replacement of the ascending aorta (Bentall procedure) (n = 4), and repair of open foramen ovale (n = 1). All 30 patients were extubated within 15 minutes after surgery at 36.5 degrees C (36.4 degrees C-36.6 degrees C). There was no need for reintubation. Pain scores were low immediately after surgery and 6, 24, and 48 hours after surgery at 0 (0-3.5), 0 (0-2), 0 (0-2), and 0 (0-2), respectively. During and up to 6 hours after surgery, there was no significant hemodynamic change due to TEA. Fifteen of 30 patients needed temporary pacemaker activation. There were no complications related to TEA. Conclusions: Immediate extubation is feasible after aortic valve surgery with high thoracic epidural analgesia and maintenance of hemodynamic stability throughout surgery. Immediate extubation after aortic valve surgery is a promising new path in cardiac anesthesia.

Alcohol--a perioperative problem of anaesthesia and intensive care medicine

Alcohol is a socially tolerated drug. Its consumption is associated with several physiological and pharmacological negative side-effects during anaesthesia and intensive care. The impact of chronic and acute alcoholism on perioperative morbidity and mortality and especially on anaesthetic risk are important, due to pharmacological interactions, pathophysiological changes and direct pharmacological interactivities between alcohol and narcotics. In contrast to opioid withdrawal symptoms of alcohol withdrawal are a serious and potentially life-threatening complication and should be avoided or the risk for occurrence must at least be reduced. Patients with a high risk of developing perioperative symptoms of alcohol withdrawal can be detected by laboratory tests and questionnaires. A prophylaxis of withdrawal should be started preoperatively solely with benzodiazepines or in combination with clonidine. Haloperidol is the drug of choice for emerging symptoms of alcohol withdrawal with productive psychosis. To estimate the pharmacological changes during anaesthesia, it is necessary to differentiate whether the patient is an occasional drinker with acute intoxication, a chronic abuser without limitations of hepatic function or a chronic user with insufficiency of the liver. The most important implication for anaesthesia are the choice of a rapid sequence induction to reduce the risk of aspiration and the maintenance of haemodynamic stability and liver perfusion. For the acute alcoholic providing prolonged postoperative surveillance is necessary, for the chronic alcoholic intensive care seems to be mandatory. For regional anaesthesia the indications and limitations are the same as for other patients (cooperativeness, coagulation, consent, etc.).

Hemodynamic profile and vasoactive drugs in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by diffuse inflammatory response in the lungs with refractory hypoxemia. The maintenance of hemodynamic stability is a key point for tissue perfusion in this syndrome.

Invited commentary

Hemodynamic instability occurs frequently during off-pump coronary artery bypass (OPCAB) as a result of manipulation of the beating heart. This is particularly the case when the heart has to be lifted and rotated during coronary surgery in order to expose the coronary vessels of the lateral and inferior wall. Under these circumstances, diastolic filling of the right ventricle is compromised, leading to a reduced blood flow to the pulmonary artery. This reduces the filling of the leftventricle, which decreases stroke volume and cardiac output. A right ventricular assist device (RVAD) used during OPCAB pumps blood to the pulmonary circulation to maintain cardiac output and stabilize systemic hemodynamics.Based on this rationale, Caputo and colleagues evaluated such a RVAD, the A-Med system, in a randomized study in OPCAB patients. A major finding of this study is a significant reduction of central venous pressure in the RVAD-supported patients during exposure of coronary vessels located on the lateral and posterior ventricular wall. This beneficial effect may have contributed to maximal left ventricular filling and maintenance of hemodynamic stability, which, regrettably, is not detailed in this report. The findings of a reduced inflammatory response in OPCAB patients compared with on-pump patients are in line with previous publications.It seems clear that patients who are operated off-pump (ie, by eliminating the adverse effects of cardiopulmonary bypass on blood elements and humoral components) develop a far lesser postoperative inflammatory response than patients that are operated on-pump. However, surgical trauma and other operative events still cause a mild to moderate inflammatory response in OPCAB patients, as seen in this report by a transient postoperative elevation of Interleukine-6, Interleukin-8, complement C3a, and markers of organ injury Troponin I and S100. According to this study, there seems to be no difference between the OPCAB and RVAD patients regarding their postoperative inflammatory response and organ function, which suggests that the use of this RVAD does not promote inflammation indicated by comparable inflammation as in OPCAB patients without RVAD.As OPCAB operations are now more widely applied in coronary surgery, it is important to investigate which category of patients, especially those with high-risk profiles who benefit most from RVAD support. Hemodynamic instability occurs frequently during off-pump coronary artery bypass (OPCAB) as a result of manipulation of the beating heart. This is particularly the case when the heart has to be lifted and rotated during coronary surgery in order to expose the coronary vessels of the lateral and inferior wall. Under these circumstances, diastolic filling of the right ventricle is compromised, leading to a reduced blood flow to the pulmonary artery. This reduces the filling of the leftventricle, which decreases stroke volume and cardiac output. A right ventricular assist device (RVAD) used during OPCAB pumps blood to the pulmonary circulation to maintain cardiac output and stabilize systemic hemodynamics. Based on this rationale, Caputo and colleagues evaluated such a RVAD, the A-Med system, in a randomized study in OPCAB patients. A major finding of this study is a significant reduction of central venous pressure in the RVAD-supported patients during exposure of coronary vessels located on the lateral and posterior ventricular wall. This beneficial effect may have contributed to maximal left ventricular filling and maintenance of hemodynamic stability, which, regrettably, is not detailed in this report. The findings of a reduced inflammatory response in OPCAB patients compared with on-pump patients are in line with previous publications. It seems clear that patients who are operated off-pump (ie, by eliminating the adverse effects of cardiopulmonary bypass on blood elements and humoral components) develop a far lesser postoperative inflammatory response than patients that are operated on-pump. However, surgical trauma and other operative events still cause a mild to moderate inflammatory response in OPCAB patients, as seen in this report by a transient postoperative elevation of Interleukine-6, Interleukin-8, complement C3a, and markers of organ injury Troponin I and S100. According to this study, there seems to be no difference between the OPCAB and RVAD patients regarding their postoperative inflammatory response and organ function, which suggests that the use of this RVAD does not promote inflammation indicated by comparable inflammation as in OPCAB patients without RVAD. As OPCAB operations are now more widely applied in coronary surgery, it is important to investigate which category of patients, especially those with high-risk profiles who benefit most from RVAD support.

Immunonutritive enteral feeding in the critically ill

Since imbalances in the immune system of the critically ill patient have been demonstrated, the role of the gastrointestinal tract for the pathogenesis of multiple organ failure has been a focus of research in intensive care medicine. Particularly, the integrity of the intestinal barrier function has been studied experimentally and clinically. The enormous number of gram-negative bacteria up to 10(11)/ml intestinal liquid inducing the release of significant amounts of endotoxin, is considered to be a vital threat to the intensive care unit (ICU) patient. Acute failure of the intestinal barrier following various types of severe shock or following parenteral nutrition inducing atrophy of intestinal mucosa may lead to multiple organ dysfunction. Maintenance of hemodynamic stability is a mainstay of therapy of the critically ill. In addition, the intestinal integrity can be preserved by the early onset of enteral nutrition. Moreover, recent concepts of enteral nutrition using immunomodulating nutrients like omega-3-fatty acids, glutamine, arginine, and nucleotides are under clinical evaluation.

Risk of spinal cord ischemia after endograft repair of thoracic aortic aneurysms

Background: Surgical repair of thoracoabdominal aneurysms may be associated with a significant risk of perioperative morbidity including spinal cord ischemia, which occurs at a rate of between 5% and 21%. Spinal cord ischemia after endovascular repair of thoracic aortic aneurysms (TAAs) has also been reported. This investigation reviews the occurrence of spinal cord ischemia after endovascular repair of descending TAAs at the Mount Sinai Medical Center. Patients and Methods: Between May 1997 and April 2001, 53 patients underwent endovascular exclusion of their TAA. Preprocedure computed tomography scanning and angiography were performed on all patients. All were performed in the operating room using C-arm fluoroscopy. Physical examinations and computed tomography scans were performed at discharge and at 1, 3, 6, and 12 months postoperatively and then annually thereafter. Spinal cord ischemia developed in three of the 53 patients (5.7%) postoperatively. In one patient, cord ischemia developed that manifested as early postoperative left leg weakness occurring after concomitant open infrarenal abdominal and endovascular TAA repair. The neurologic deficit resolved 12 hours after spinal drainage, steroid bolus, and the maintenance of hemodynamic stability. The remaining two patients developed delayed onset paralysis, one patient on the second postoperative day and the other patient 1 month postrepair. Both of these patients had previous abdominal aortic aneurysm repair, and both required long grafts to exclude an extensive area of their thoracic aortas. Irreversible cord ischemia and paralysis occurred in both of these patients. Conclusions: Endovascular repair of TAA has shown a promising reduction in operative morbidity; however, the risk of spinal cord ischemia remains. Concomitant or previous abdominal aortic aneurysm repair and long segment thoracic aortic exclusion appear to be important risk factors. Spinal cord protective measures (ie, cerebrospinal fluid drainage, steroids, prevention of hypotension) should be used for patients with the aforementioned risk factors undergoing endovascular TAA repair. (J Vasc Surg 2001;34:997-1003.)

Intravenous Dopamine Associated with Nephrogenic Diabetes Insipidus-Like Syndrome

Dopamine is often used for maintenance of haemodynamic stability in critically ill patients in the setting of intensive care units. ‘Renal’ doses (1 to 2 μg/kg/min) or ‘pressor’ doses (above 5 to 10 μg/kg/min) are used distinctly for various clinical disorders. Dopamine may be associated with diabetes insipidus, manifested by serum hypertonicity, urine hypotonicity and polyuria.[1] The mechanism of the potentiation of free water excretion remains obscure, although inhibition of pituitary vasopressin or increased solute excretion have been proposed.[1] In this case report, we describe a patient who developed acute diabetes insipidus associated with dopamine administration, where neither of these mechanisms appears likely.

Optimal Dose of Nicardipine for Maintenance of Hemodynamic Stability After Tracheal Intubation and Skin Incision

Optimal Dose of Nicardipine for Maintenance of Hemodynamic Stability After Tracheal Intubation and Skin Incision

May Cardiovascular Stability Be Achieved with Both Sevoflurane and Desflurane?

In Response: In our comparison of sevoflurane and desflurane for maintenance of general anesthesia during laparoscopic tubal ligation procedures, the use of adjunctive drugs was standardized [1]. As a result, the doses of propofol (131 +/- 34 vs 138 +/- 58 mg), fentanyl (216 +/- 49 vs 211 = 59 micro g), and vecuronium (7.7 +/- 1.4 vs 7.6 +/- 1.7 mg) were almost identical in the two study groups. We would agree with Dr. Martinez-Laborde that the study design would have been more "pure" if only the two volatile anesthetics were being titrated during the maintenance period. However, in the absence of opioid supplementation, maintenance of hemodynamic stability would have required significantly higher concentrations of both desflurane and sevoflurane, resulting in a slower emergence from anesthesia. In the ambulatory setting, prolonged emergence times can result in longer turnover times between cases. We are currently performing a prospective randomized comparison of sevoflurane and desflurane in this same outpatient population. In our follow-up study, the two volatile anesthetics are the only drugs being titrated during the maintenance period. Finally, in the United States, patients of Mexican (and Central American) descent are classified ethnically as "Hispanic." This system is certainly not intended to offend individuals of Spanish origin. Please accept our apology if this ethnic classification system has offended you and your colleagues in Spain. Paul F. White, MD, PhD Michael H. Nathanson, FRCA Brian Fredman, MB, Bch Ian Smith, FRCA Department of Anesthesiology and Pain Management University of Texas Southwestern Medical Center Dallas, TX 75235-8894

Syncope and the Autonomic Nervous System

The autonomic nervous system plays a central role in the maintenance of hemodynamic stability. Dysfunction of this complex regulatory system can lead to the development of loss of consciousness. This article summarizes our current understanding of the role of the autonomic nervous system in maintaining a stable blood pressure and heart rate under normal and abnormal physiologic conditions. The role of baroreceptors, mechanoreceptors, chemoreceptors, vascular reactivity, and the interaction of these sensor systems with the central nervous system as a whole are reviewed. Current concepts related to the mechanisms of unexplained syncope and the "state-of-the-art" diagnostic and treatment options are also discussed.

Perioperative use of propofol for cardiac surgery

Worldwide, approximately 750,000 cardiac surgeries are being performed annually. No fundamental differences have been demonstrated between anesthesia for cardiac versus noncardiac surgery.* If used appropriately, virtually all available anesthetics are suitable for cardiac surgery. To achieve adequate general anesthesia, a minimum of two different classes of anesthetic drugs is usually required.* In patients with cardiac disease, the maintenance of hemodynamic stability is considered important for reducing the incidence of adverse cardiovascular outcomes. Because opioids are associated with relative hemodynamic stability, they are the most commonly used primary anesthetics during cardiac surgery. Supplementation with potent inhalational anesthetics, benzodiazepines, or other anesthetics is required. Opioid anesthesia is associated with a small incidence of hypotension, especially on induction of anesthesia. Intraoperative hypertension also may occur. Potent inhalational anesthetics and intravenous (IV) sedative-hypnotics such as benzodiazepines are also used as the prirnary anesthetics for cardiac surgery. Other sedative-hypnotics such as propofol are being used during cardiac surgery. Compared with most anesthetics, propofol allows easier titratability and more rapid emergence.s-5 Su pplementation of propofol with an opioid leads to a synergistic interaction.* Propofol can be used for preoperative sedation as an anesthetic and for postoperative sedation. Propofol has certain disadvantages. It may contribute to hypotension and bradycardia.3-6 This may be especially true for cardiac surgery patients who are often given antihypertensive, antiischemic, and vasodilator medications such as beta-blockers and calcium-channel blockers. Anesthetics including propofol and opioids cause hypotension because of loss of sympathetic tone. In addition, propofol also has a dose-dependent hypotensive effect. This leads to lesser hemoclynamic stability and greater need for titration when propofol is used. Propofol infusion may have 70 be titrated frequently and skillfully to avoid hypotension on one hand and light anesthesia on the other. The bradycardiac effects *Assistant Professor of Anesthesia

Neurologic function and neuromuscular blocking agents in critical care.

Neuromuscular blocking agent (NMBA) use in critical care units is generally reserved for life threatening situations. The goal of any life-support effort, including efficient mechanical ventilation, maintenance of hemodynamic stability, and NMBA use, is to optimize cerebral preservation. Yet, although all other organ systems are aggressively monitored, very little is done to assess neurologic stability during NMBA therapy. This article addresses the neurologic issues associated with NMBA use: identification of those patients at risk for a neurologic event; rationale for monitoring cerebral changes during paralytic therapy; and potential means of assessing and intervening before, during, and after chemical paralysis.

Surgical management of hepatoma.

For the majority patients with HCC, the prognosis is poor. Only a fraction of patients will be resectable at the time of their diagnosis. For the oncologic surgeon caring for such patients, the challenges are multifaceted. First, he or she must have a familiarity with current imaging techniques and reliable support from a radiologist to determine whether a given patient can be technically resectable. We rely most heavily upon the initial diagnostic CT scan followed by the staging CTAP in order to define the resectable patient as clearly as possible. Additionally, the risk of postoperative hepatic failure must be assessed. Careful physical exam, blood chemistries, and volumetric analysis of CT scans demand much judgment on the part of the surgeon. While some patients are clearly capable of undergoing a resection, and others are clearly inoperable due to poor hepatic function, a large group of patients exist in a "gray area" where resection can be entertained but the risk of hepatic failure looms large. In this group the use of the ICG retention test or the 14C-aminopyrine breath test are occasionally useful. Further research into better assessment of hepatic reserve is clearly needed. Once a laparotomy is undertaken, IOUS is a key component of intraoperative staging and the final determinant of resectability. Resection itself must be performed with three goals: Resection of all disease with negative surgical margins, retention of as much hepatic parenchyma as possible in keeping with oncologic principles, and maintenance of hemodynamic stability with minimal transfusion requirements in an effort to minimize the stress of surgery. The combination of vascular control and the porta hepatis (and IVC where necessary), segmental hepatic resection where appropriate, and ultrasonic dissection can accomplish these goals. Intrahepatic recurrence, despite adequate resection, can be expected in many patients, and few will be candidates for a second resection. For this reason, and because most patients are unresectable at presentation, the oncologic surgeon must be familiar with palliative options available for his patients, as well as the surgical management of operable tumors. Close collaboration with one's colleagues in medical oncology, invasive radiology, and gastroenterology are critical to the optimal care of this difficult patient population.

L’utilisation du sulfate de magnésium pendant la chirurgie du phéochromocytome: à propos de deux cas

Maintenance of haemodynamic stability during anaesthesia for phaeochromocytoma resection is still a challenge. If magnesium sulfate is widely used for the control of arterial pressure during preeclampsia, its use during phaeochromocytoma resection has only been published by one author. We describe two cases where magnesium sulfate is the main agent used to control arterial pressure during resection of a phaeochromocytoma. Magnesium sulfate's hypotensive, antiarrhythmic and antiadrenergic properties are reviewed. The total doses administered were 11 g and 12 g, given as an infusion and boluses. Magnesium sulfate could be part of the anaesthetist's pharmacopoeia during phaeochromocytoma resection.

Prevention of secondary cardiovascular instability after intestinal ischemia and reperfusion improves survival

Previous studies of small intestinal ischemia and reperfusion (I/R) in immature rats report secondary systemic organ injury and low survival rates; however, in these studies the cardiovascular stability of the rat was not established. To prevent the secondary hemodynamic deterioration accompanying intestinal I/R, we have developed a model that utilizes aggressive fluid resuscitation. Under anesthesia, 4-wk-old male Sprague-Dawley rats (n = 189) underwent 90 min of I/R (superior mesenteric artery occlusion) or sham (SH) operation while receiving lactated Ringer with 5% dextrose at 15 (IR15, SH15) or 65 (IR65, SH65) ml.kg-1 x h-1 i.v. The results indicate that aggressive fluid resuscitation in the IR65 group significantly attenuated the hypotension, hemoconcentration, metabolic acidosis, and amount of gross bowel injury observed in the IR15 group, while increasing postreperfusion renal and intestinal blood flow, prolonging survival time of nonsurvivors, and improving overall group survival. These findings suggest that maintenance of hemodynamic stability is necessary in models of bowel I/R. Furthermore, this model allows for selective study of the isolated effects of intestinal I/R without the additional complications resulting from secondary cardiovascular instability.

The diagnosis and perioperative management of myocardial ischaemia.

Perioperative myocardial ischaemia is common in patients who have or are at risk of coronary artery disease, occurring frequently in the pre-, intra- and postoperative periods. The majority of perioperative ischaemic episodes are silent, being unaccompanied by any symptoms of angina. The use of appropriate preoperative laboratory investigations may help in the diagnosis of CAD and the prediction of risk of adverse cardiac outcome. A properly placed and properly calibrated ECG is the best overall monitor of ischaemia. Maintenance of haemodynamic stability is important to reduce the incidence of myocardial ischemia, but ischaemia may occur in the absence of adverse haemodynamic changes. Although our efforts have largely been devoted to the prevention and treatment of intraoperative ischaemia, it is hoped that similar efforts outside the operating room in the postoperative period will further improve patient care and outcome.

Maintenance of Hemodynamic Stability during Induction and Endotracheal Intubation

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