Showing papers in "Journal of Intensive Care Medicine in 1993"

Nutrition and Nutritional Support in Critically Ill Patients

Abstract: The use of intravenous nutritional support has increased dramatically in the last 20 years. Although it is not without controversy, administration of nutritional support is common practice in hospitalized patients including critically ill patients. Malnutrition continues to be reported in a significant number of hospitalized patients. The incidence of malnutrition in critically ill patients may be even higher than that reported in hospitalized patients overall. The consequences of malnutrition in a critically ill patient may be severe. Nutritional assessment and nutritional support can present special challenges to the intensivist. Techniques of nutritional assessment in critically ill patients are evaluated. Guidelines for the determination of the nutritional needs of these patients are outlined. Methods of delivery of nutritional support in critically ill patients are reviewed. Complications of nutritional support are discussed.

Chest tubes: indications, placement, management, and complications.

Abstract: Use of tube thoracostomy in intensive care units for evacuation of air or fluid from the pleural space has become commonplace. In addition to recognition of pathological states necessitating chest tube insertion, intensivists are frequently involved in placement, maintenance, troubleshooting, and discontinuation of chest tubes. Numerous advances have permitted safe use of tube thoracostomy for treatment of spontaneous or iatrogenic pneumothoracies and hydrothoracies following cardiothoracic surgery or trauma, or for drainage of pus, bile, or chylous effusions. We review current indications for chest tube placement, insertion techniques, and available equipment, including drainage systems. Guidelines for maintenance and discontinuation are also discussed. As with any surgical procedure, complications may arise. Appropriate training and competence in usage may reduce the incidence of complications.

Overview of Exogenous Surfactant Replacement Therapy

Abstract: We review and analyze the various exogenous surfactant agents used in randomized, controlled clinical trials in infants with or at risk for respiratory distress syndrome (RDS). Analysis of all published trials utilizing natural, or modified natural, surfactant extracts or syntheticsurfactants inpremature infants at risk for RDS treated at birth (prophylactic treatment) shows an improvement in the need for supplemental oxygen and ventilatory support over the course of RDS and a reduction in many morbidities of prematurity, especially pneumothorax, but little or no impact on the incidence of intraventricular hemorrhage. Treatment of established RDS alter onset of mechanical ventilation is also reviewed, showing similar improvements over the course of RDS and lessening of morbidities, including pneumothorax. Overviews of study results account for the effect of treatment, the number of infants included, and the power of the outcomes; studies of similar design are compared using meta-analysis that which clearly documents the impact of surfactant therapy (both prophylactic and postventilatory treatment) on neonatal mortality. Comparisons between outcomes of studies comparing prophylactic to later treatment found no clear advantage of preventative treatment, except among infants less than 26 to 28 weeks’ gestation. Variations in response to surfactant treatment due to high permeability lung edema, decreased pulmonary perfusion, lung hypoplasia, and obstructive lung disease are reviewed, and the effects of dose and multidose therapy clearly document that doses between 100 to 200 mg/kg of modified natural surfactants are optimal, although there is no specific advantage of more than two doses of synthetic surfactant. Complications of surfactant therapy include transient hipoxia and hypercarbia during administration, an increased occurrence of pulmonary hemorrhage, and concerns regarding imrnunogenicity of surfactant proteins contained in natural o r modified surfactants. Long-term follow-up studies have been uniformly encouraging among infants treated with exogenous surfactants.

Myopathy in Status Asthmaticus: Relation to Neuromuscular Blockade and Corticosteroid Administration

Abstract: Myopathy is a rare complication that arises during management of status asthmaticus that may be related to administration of corticosteroids and neuromuscular blocking agents. We present 4 patients with myopathy and a review of the 31 previously reported patients in the literature. All patients received corticosteroids, and 33 of the 35 patients received neuromuscular blocking agents. Muscle weakness was often diffuse and, in several patients, involved the muscles of respiration. Creatine kinase values ranged from normal to markedly elevated. Diagnosis was obtained by electromyogram and muscle biopsy in most patients. Resolution of the muscle weakness occurred over a period of days to months. Patients in whom myopathy developed required mechanical ventilation for longer periods than patients intubated for status asthmaticus without myopathy.

Use of Muscle Relaxants in the Intensive Care Unit

Abstract: Muscle relaxants are now routinely used in intensive care units despite the relative paucity of literature regarding their use, safety, and efficacy in this setting. Although the theory of the phar...

Intraventricular Hemorrhage: An Update

Abstract: Although the incidence of intraventricular hemorrhage (IVH) has decreased in recent years, the increasing survival rates for the smallest premature infants indicate that the lesion will continue to...

Recognition and Management of Anxiety in the Intensive Care Unit

Abstract: Anxiety is common among patients receiving intensive care. We discuss the signs and symptoms of anxiety in the intensive care unit. Appropriate treatment of anxiety should be initiated in a timely fashion so that patient compliance with treatment will be enhanced and the morbidity associated with critical illness can be reduced. Pharmacological and nonpharmacological strategies for management of anxiety are also presented.

Fracture Fixation Timing in Critically Ill Patients

Abstract: 1 review the management of trauma patients with musculoskeletal injuries, with special emphasis on the timing of operative fracture kxation. Initial management of multiple trauma patients with concomitant musculoskeletal injuries should be directed at potentially life-threatening injuries, such as ;Linvay, breathing, or hemorrhage control. Once the potentially life-threatening injuries have been stabilized, accumulated evidence from the literature suggests that operative fracture fixation within 24 hours decreases morbidity (i.e., adult rFpirator). distress syndrome, fat embolism, septic complications, pneumonia) and mortality, decreases pain at the fracture site, and allowvs for earlier functional rehabilitation of the affected extremity. An exception may be elderly patients with concomitant medical problems who sustain isolated fractures from a low-impact trauma. In this type of patient, a brief period of up to 72 hours following injury may prove beneficial to optimize hemodynamics and stabilize other associated medical conditions. Clinical symptoms and treatment of the fat embolism syndrome are discussed. Prevention of the fat embolism syndrome involves adequate volume resuscitation and early (within 24 hr) operative fracture fixation. Other adjunctive treatments for the fully established syndrome are also discussed. Finally, the principles of the management of open fractures, including early (within 6-8 hr) debridement, antibiotics, and kxation, are reviewed. Injuries to the musculoskeletal system are the most commonly encountered injuries in patients who sustain blunt trauma and, as such, contribute significantly to the workload of most trauma centers. In severely injured multiple trauma patients, the management of musculoskeletal injuries many times is relegated to secondary importance in the rush to attend to life-threatening injuries. Although infrequently the cause of mortality in trauma patients, musculoskeletal injuries can be the cause of major morbidity and impact significantly long term on the independent lifestyle of that patient. Of special consideration are musculoskeletal injuries in the elderly, which have increased three-fold in the past several decades [l] and represent a significant portion of our health care economy [2]. The ability of critical care practitioners to positively interface in patients with musculoskeletal injuries can significantly decrease morbidity and mortality, improve the functional outcome of the affected extremity, and possibly make the difference between an individual who is returned as a working ta..paying member of society versus one who is permanently crippled, possibly institutionalized, and dependent on society to support their disability for the rest of their life. I present initial management and data with regard to the optimal timing and logistics of fracture fixation in trauma patients. In addition, the critical care management of fracture fixation in the elderly is discussed with emphasis on how the physiological changes associatedwith aging and concomitant disease processes can confound the management of these injuries. Finally, the fat embolism syndrome and management of open fractures are discussed.

A comprehensive review of vascular ultrasound for intensivists.

Abstract: Ultrasound has an increasingly important role in evaluation of the vascular system. Ultrasound is especially useful for intensive care patients because of the frequency of vascular complications developing in the ICU setting, as well as the ability of ultrasound to be performed at the patient's bedside. Ultrasound is the method of choice for evaluation of deep vein thromboembolic disease of the lower extremity in all patients; it demonstrates excellent sensitivity and specificity for this condition. It should also be the initial method of evaluation of upper extremity deep vein thrombosis. However, ultrasound may be limited in this assessment due to lack of reliably demonstrating the central subclavian and innominate veins, and therefore may be inadequate for evaluation of malfunctioning central venous catheters. Ultrasound can reliably identify and potentially be used to treat arterial complications of arterial catheterization, such as pseudoaneurysms. Similarly, ultrasound is accurate in the diagnosis of the presence of abdominal aortic aneurysm, and ultrasound can be used to assess carotid and lower extremity arteries noninvasively. Finally, ultrasound is useful for evaluation of hemodialysis fistulas and vascular complications of transplants.

Thrombolytic Therapy: A Comprehensive Review of Its Use in Clinical Medicine. Part II

Abstract: The second part of this comprehensive review of thrombolytic therapy in clnical medicien focuses on its use in a wide renge of thrombotic disorders, including pulmonary embolism, deep venous thrombosis, arterial thrombocmbolism, catheter-related thrombosis, arterial thrombocmbolism, catheter-relted thrombosis, and prosthetic valve occlusion. New experimental applications in the management of unstable angina and cerebrovascular disease are also discussed.

Cholesterol Embolism in Intensive Care Patients

Abstract: Four case reports are presented, followed by a discussion of the acute, potentially life-threatening manifestations of the cholesterol embolism syndromes. Every major organ system except the lungs may be directly affected by cholesterol emboli; devastating consequences encompass cerebral, myocardial, spinal cord, intestinal, renal, and other visceral organ infarction, as well as peripheral and perineal gangrene. Additional complications include severe hypertension, gastrointestinal bleeding, and hemodynamic instability. Anticoagulants and thrombolytic therapy may exacerbate atheromatous embolism and are relatively contraindicated. Aggressive supportive therapy may improve chances of survival, but long-term prognosis is poor. Prevention remains the most important aspect in this devastating disorder.

Rheumatic Disease in the Intensive Care Unit: Acute Septic Arthritis and Giant-Cell Arteritis

Abstract: Acute septic or bacterial arthritis is an important cause of morbidity and mortality, particularly in the elderly, and its incidence may be increasing. Rapid destruction of intraarticular structures may occur. Individuals with underlying arthritis and those with immune deficiency states are particularly at risk Most patients present with an acute monoarthritis, commonly involving the knee joint, although polyarticular septic arthritis may occur in patients with overwhelming sepsis. The most common organism is Sfnpbylococcrrs nureus Synovial fluid examination and culture is critical to diagnosis. Treatment of bacterial arthritis employs appropriate antibiotic therapy combined with adequate joint drainage. Giant-cell arteritis is a form of vasculitis that affects predominantly middle-aged and older persons. Its pathophysiology is unknown, although increasing evidence indicates disturbances in immune function. Initial symptoms are nonspecific, but commonly consist of headache, muscle aches, and stiffness, and constitutional symptoms of fever, weight loss, and anorexia. Permanent visual loss is a catastrophic complication due to involvement of the posterior ciliary artery. Other neurological complications, including occlusive disorders of the aortic arch and stroke syndromes. have recently been recognized. The diagnosis of giant-cell arteritis is made by temporal artery biopsy, and appropriate management includes use of corticosteroid therapy.

Asystole Associated with Lidocaine Use in a Hyperkalemic Patient during Advanced Cardiac Life Support

Abstract: A case report of fatal asystole associated with use of lidocaine in a hyperkalemic patient is presented The patient was a 61–year-old man with a rapidly increasing serum potassium level related to acute renal failure Ventricular tachycardia with a pulse developed twice, for which lidocaine was administered according to the American Heart Association's ACLS protocol Both episodes were immediately followed by asystole, the second of which was terminal Available information suggests that this phenomenon can be explained by a synergistic effect on membrane responsiveness and conduction velocity Thus, extreme caution should be exercised in the use of lidocaine when ventricular tachycardia complicates severe hyperkalemia

Why Isn't This Patient Awake?

Abstract: (Setting: morning rounds in the AIedical intensive care unit [hIICU]). (Players: Als Jones, a septic patient; the medical PGY-3 in charge of the hlICU; the patient’s primary nurse, and a fourth-year medical student on rotation.) Resident: “Good morning, hls Jones.” his Jones: (no response) Resident (shouting in hls Jones’s ear): “Open your eyes! Squeeze my hand!” hls Jones:‘(no response) Resident (walking away from the patient, studying the flowsheet): “The SVR is way down. I guess she’s getting more septic.” Student (looking puzzled): ‘Why isn’t this patient awake?” Resident (looking annoyed): “Because she’s very sick.” Nurse (looking perturbed): “Aren’t you gong to get a CT scan? \\%en hIr Smith did this, he had bled into his head. And what about the brain abscess we found 2 months ago?” Resident (feeling threatened) to student: ‘This woman is too sick to go to radiology. hlaybe we’d better get a neurology consult to cover ourselves.” Student (sensing impending s a t work): “They’ll just want a bunch of tests, and finally come see her after she’s either better or dead.” Nurse (inaudibly): “Blust have been slim pickings for the admission committee a few years ago.”

Diagnosis, Management, and Complications of Nonpenetrating Cardiac Trauma: A Perspective for Practicing Clinicians

Abstract: We provide a state-of-the-art review for practicing clincians concerning diagnosis and treatment of patients with non-penetrating cardiac trauma Internists, cardiologists, and intensivists are becoming increasingly involved in the diagnosis and management of patients with nonpenetrating cardiac injuries Electrocardiography and cardiac isoenzyme determinations are the least expensive and most common laboratory tests used to diagnose this condition Despite widespread use, however, these tests have significant limitations in diagnostic sensitivity and specificy Two-dimensional echocardiography is advocated by some to improve diagnostic accuracy and to identify patients at increased risk of cardiovascular complications Patients identified as low risk may be suitable for limited monitoring and early hospital discharge Transesophageal echocardiography is a useful diagnostic tool that offers many advantages over standard transthoracic imaging Nuclear medicine techniques, including radionuclide-labeled ant

Noninvasive evaluation of newborns with congenital heart disease.

Abstract: Over the last decade, diagnosis and management of neonates with congenital heart disease have been greatly influenced by the constant expansion of noninvasive methods. We classify the most common congenital defects presenting in the first 2 weeks of life, based on clinical presentation and hemodynamic characteristics, followed by a discussion of echocardiographic findings in the most common congenital heart lesions and how ultrasound techniques can help solve problems frequently encountered during the early postoperative period.

L-tryptophan-associated eosinophilia-myalgia syndrome: Clinical and pathological features of an evolving new disease and current concepts of etiology

Abstract: The eosinophilia-myalgia syndrome (ENS) is a newly recognized illness that occurred in the United States and in other countries in an'epidemic form during 1989. The outbreak was associated with ingestion of the essentid amino acid Ltryptophan. The illness appears to be heterogeneous; it has an early phase characterized by myalgia, skin rashes, constitutional symptoms, and marked peripheral blood eosinophilia, f o l l o n d by a late phase characterized by chronic cutaneous, neuromusculx, pulmonary, and other manifestations. Because EMS has no pathognomonic findings, the diagnosis is based on recognizing the characteristic clinical and laboratory features of the syndrome, supported by the histopathological findings of inflammation and fibrosis of the subcutaneous fascia and the connective tissue structures surrounding skeletal muscle and peripheral nerve fibers. Toxicoepidemiological studies suggest that the epidemic of EXIS was caused by a point-source contamination of Ltryptophan preparations. Analysis of L-tryptophan preparations identified a tryptophan-related novel amino acid present only in batches associated n-ith EMS. but extensive studies with animals have thus far failed to establish an etiologic role for this contaminant in EXIS. A recently identified second contaminant is chemically similar to analide derivatives isolated from samples of cooking oils that caused the toxic oil epidemic in Spain. Experimental studies suggest a major role for eosinophil and fibroblast activation in the pathogenesis of EMS. This newly recognized illness has focused intense interest on the role of chemical and environmental agents in the pathogenesis of various idiopathic illnesses characterized by inflammation and fibrosis.

Coronary Restenosis after Angioplasty

Abstract: Since the introduction of percutaneous transluminal coronary angioplasry in 1977, exponential growth in its application has occurred. Despite the improvements in the technology used to perform angioplasty and numerous trials evaluating pharmacologic agents, recurrent arterial commonly narrowing termed restenosis remains a major limitation in the application of this procedure. Restenosis is in fact not a single entity but the result of several factors which may be interrelated. These include (1) suboptimal dilation, (2) elastic recoil, (3) residual dissection, (4) intraluminal thrombus, ( 5 ) intramural thrombus, (6) myointima1 prolifeiation, and (7) progression of native disease. Each of these play an important role in patients who present with recurrent myocardial ischemia after angioplasty. Recurrent stenosis is a temporally related phenomenon. It may occur acutely, within the first 24 hours after PTCA when it is most often due to thrombosis or coronary dissection. Subacutely, presentations between 10 days and 4 months are typically due to inadequate dilation or myointimal proliferation. Recurrent symptoms after 6 months is typically due to the development of new atherosclerotic lesions or progression of other disease. The clinical manifestations of restenosis occur within the first 6 months. Typically, the patients will hare a recurrence of their anginal symptoms. although 15% may be asymptomatic with an abnormal exercise test. While angiographic stenosis, defined typically as a luminal narrowing greater than 50%. occurs in 30% to 50% ofpatients, clinical restenosis occurs in only 15% to 20% of patients. This phenomenon can be explained by the fact that a 50% arterial narrowing may not decrease coronary blood flow sufficiently to result in coronary ischemia. Attempts to decrease restenosis have included the de\\-elopment of new coronary devices such as stents, atherectomy catheters, and laser systems. which are all still being evaluated. The other major approach has been the use of pharmacologic agents. A large number of agents have been evaluated, including aspirin, heparin, lipid lowering drugs, calcium and beta blockers, cytotoxic agents, and ace inhibitors. Despite the succcss of these medications in decreasing restenosis in animal models none have reproductibly n-orked in humans. Restenosis remains the major problem in patients who h a w undergone coronary angioplast). despite intensive research. From our current understanding of restenosis, we can hopefully develop new avenues of research to combat this important clinical problem.

Uses and Limitations of Echocardiography in Neonatal Intensive Care Units

Abstract: The estraordinan advances made in echocardiography and Doppler color flow mapping have greatly facilitated diagnosis of congenital heart disease; to a large extent, what used to be an alniost routine use of cardiac catheterization has been displaced bf these techniques. They have been of help in three main areas: (1) in diagnosis of the type and severity of apparently mild congenital heart disease; (2) in the follow-up of patients Lvith known heart disease to determine tlie functional status of the heart; and (3) in critically ill newborn infants. The last use is particularly important, because these are infants who need the quickest and the most accurate diagnosis, yet are those in whom cardiac catheterization has substantial risks. The review by Ibmaciotti and Chin in this issue of tlie Jota-nnl indicates how much can be achieved by modern high-resolution echocardiography combined with Doppler studies. Tliere are some c;ive;its that those not familiar with echocardiography should bear in mind. First, diagnostic results are good only in the hwds of those who are experienced in pediatric c a r d i o l o ~ and pediatric echocardiography. Adult ecliocnrdiographers or echocardiographic technicians who see children only occasionally may be unable to make the correct diagnosis. As pointed out by Ibmaciotti and Chin, certain abnormalities are still beyond tlie ability of the technique to diagnose, including intramural coronary arteries or close approximation of the nvo coronary ostia in transposition of the great arteries, identification of an anomalously originating left anterior descending coronary ar ten from the right coronary artery in infants with tetralog). of Fallot (an important variant that occurs in a high percentage of these infants), and peripheral pulmonary arterial stenoses in pulmonary atresia or tetralogy of Fallot. Other anomalies that are larger and thus technically detectable may still lead to misdiagnosis. Coarctation of tlie aorta is one of tlie lesions that may still be misdiagnosed, even in the best hands. It is possible to fail to identih the Fpical shelf because of limited resolution at what is a considerable distance for the equipment, and it is possible to find a slielf that is actually an artifact of the beam angulation. Therefore, diagnosis of coarctation should always be confirmed by the ductus arteriosus flow patterns described by the authors and also by examining the acceleration of flow above and below tlie coarctation. If there is significant obstruction in tlie region of tlie coarctation, there ivill be a much slo\\ver acceleration below than above the coarctation, and this sign should aln.riys be sought. Ecliocmiiography is also useful to assess cardiac function immediately after surgen, as lvell as to in deterniine the potential causes of low cardiac output, including residual major lesions, myocardial failure, Iiypovoleniia, o r pericardial tamponade. tts Ibniaciotti and Chin point out, postoperative echocardiography is technically difficult because of chest bandages and lung inflation from ventilators, and there will certainly be ;i role for transesophageal echocardiography n.lien the equipment become satisfactorily miniaturized. There are certain unesp1:iined failures of echocardiography. Determining the pressure gradient across a pulmonary arterial band should follow the principles of detecting m y stenotic lesion, but often the echocardiogram shows what appears to be a tight band when in fact the distal pulmonary arterial pressure is high enough to cause pulmonary vascular disease. In our hands, this risk has been serious enough that we routinely recatheterize these infants 1 to 2 months later to make certain that tlie pulmonary vasculature is not being compromised. Assessing tlie amount of regurgitation is, as the authors point out, still inadequate, as is accurate measurement of pulmonary arterial pressure. The more echocardiography is compared with other techniques, such as cardiac catheterization, computerized tomography, angiocardiography, and magnetic resonance imaging. tlie more occasional discrepancies are found; no one method is perfect. Tlierefore, echocardiography should be treated like any other diagnostic technique; it is extremely valuable, but is capable of error, even in the best hands, so that its findings must be reconciled with every-

A 37-Year-Old Woman with Altered Mental Status, Fever, and Renal Failure:

Abstract: Dr A fork Nitzberg (Resident in Alediciire, Uii i~wsip of a~nsroc~i~ettsl\fe~ic~enicnl Center fLh\fi\lCJ: A 37-yearold woman was admitted through the Emergency Department (ED) of the University of Massachusetts Medical Center (UAIRIC); she was found unresponsive on the floor of her apartment by emergency medical technicians, who had been called after she could not be reached on the telephone by her psychiatrist that day. In the field, she had a palpable systolic blood pressure of 110 mm HG and 12 to 14 spontaneous respirations per minute. The patient had not been intubated nor had medications been administered prior to her arrival in the ED. Important points in the patient's past medical history included polysubstance abuse with multiple overdoses (most recently 4 weeks prior to admission), atypical bipolar disorder with depression, total abdominal hysterectomy for bleeding fibroids 3 months prior to admission, and an idiopathic seizure disorder (last seizure in 1986). Her family history was unremarkable. There were no known al-

Thrombolytic Therapy: An Orchestra without a Conductor:

Abstract: Manyclinicians mistakenly have the perception that thrombolysis is a novel approach to treatment of thrombo~mbolic disease states. In fact, its history is long and extensive. Several sentinal observations have lead to our modern day understanding of thrombolysis. In 1903, Delezenne and Pozerski [1] observed that chloroform treatment of serum save rise to a proteolytic enzyme capable of dissolving blood clots; in 1949, Tillet and Sherry [2] demonstrated that extravascular clots in humans can be dissolved by local installation of streptokinase; in 1952, Johnson and Tillet [3] dissolved experimentally created rabbit ear thrombi with streptokinase infused intravenously; and in 1952, Agress and colleagues [4,5] demonstrated that fibrin clots in canine coronary arteries could be dissolved by a fibrinolytic substance (trypsin) infused intravenously. Demonstration that intravascular thrombus could be dissolved by systemic administration of thrombolytics set the stage for experimentation and clinical use in the treatment of human thromboembolic disease states, recognized collectively as the major cause of morbidity and mortality in modernday medical practice (Table 1). As the broad range of clinical utility offered by thrombolytic therapy was being recognized, potentiallimitations were noted as well. In particular, the thrombolytic agents were found to lack fibrin specificity. Furthermore, their circulating half-lives, potency, and hemorrhagic potential were considered by many to be unsatisfactory. As a result, the scientific community embarked on an intensive campaign to produce "new and improved" thrombolyrics (Table 2) [6-13]. In addition, varying dosing strategies, including prolonged, bolus, and "front loaded" infusions, were, and continue to be, investigated. Although many scientists and authorities in the field believed that newer generation thrombolytics would address the problems of thrombolytic resistance, reocclusion, and hemorrhage, others believed that adjuvant pharmacological therapy was the answer. In other words, the thrombolytics were acceptable, yet because of heightened platelet and thrombin activity in many thromboembolic disease states, additional agents would be required to achieve a maximal response (Table 3) [14-33]. Growth and development of the field of thrombolysis certainly surpasses that of any other area in medicine. There is a wealth of information concerning individual agent structure, function, and activity. Some of the advantages and disadvantages of alternative dosing strategies are also known. This knowledge, coupled with an already impressive and steadily growing assortment of adjunctive agents, places the medical and scientific communities in a challenging position. Clearly, basic science knowledge has advanced far beyond clinical research. To some, it is almost out of sight. A<:, a result, many clinicians find the area of thrombolytic therapy confusing and continue to ask the questions, "What agent should I use, for wtom, at what dose, over what period of time, with which adjunctive treatment, at what risk, at what cost?" It is time to ask an important question: "Should an already limited pool of resources for clinical research be devoted to developing each new thrombolytic or adjunctive agent that springs forth from the bench?" Clearly, the answer to this question is no; however, research dollars are currently being stretched dan-

Clinical Pharmacology in Aged Intensive Care Unit Patients

Abstract: Elderly patients are presenting themselves for advanced critical care services in ever-increasing numbers due to changing population demographics coupled with advances in medical technology and pharmacology. Medical management of the elderly in critical care settings is complicated by pre-existing multisystem chronic disease, polypharmacy, and age-related changes in pharmacokinetics and pharmacodynamics. Three principles in the management of the elderly in an intensive care unit (ICU) setting are discussed: (1) the protection of renal function from common nephrotic drugs; (2) the necessity of altered drug dosing due to changes in pharmacokinetics and pharmacodynamics; and (3) the necessity of avoiding polypharmacy. Strategies for the prevention of acute renal failure in ICU contrast studies are described. A review of pharmacodynamics and pharmacokinetics in the elderly is presented with examples of commonly seen ICU medication problems.

Regional Metabolic Supply Dependency in Chronic Congestive Heart Failure

Abstract: We present a 64-year-old man with New York Heart Association (NYHA) Class III chronic congestive heart failure (CHF) who was examined for an alteration in cerebral cortex regional oxygen utilization as reflected by changes in local cerebral metabolic rates for glucose (LCMRglu). LCMRglu was determined by positron emission tomography at baseline and while oxygen delivery (DO2) was optimized during dobutamine infusion. Baseline DO2 was 8.31 mL/min/kg and cardiac output (CO) was 3.4 L/min, whereas oxygen consumption (VO2) measured by respired gas analysis was 3.64 mL/min/kg. At optimal dobutamine effect (7.5 μg/kg/min), DO2 increased to 16.8 mL/min/kg, CO to 7.2 L/min, and VO2MEAS was 3.67 mL/min/kg. Mean percentage Increase in cortical gray matter LCMRglu was 99.4 ± 11.7% (mean ± SD) and was statistically significant (p < 0.001; Student's paired t-test). Our results demonstrate that the cerebral glucose utilization and therefore oxygen consumption increased parallel with Increases in DO2. This phenomenon is contrary to the conventional concept that cerebral perfusion is strictly autoregulated and that substrate utilization is independent of oxygen delivery.