超声心动图在抗肿瘤治疗致心肌损害监测中的作用

正近年来,随着抗肿瘤治疗的不断进步以及新型化疗药物、靶向药物等的临床广泛应用,癌症患者死亡率逐渐下降,生存期明显延长,乳腺癌的5年生存率国际上最高可达到85%以上。但与此同时,抗肿瘤治疗所致心血管并发症也逐渐得到广泛关注。所有抗肿瘤治疗(化疗、放疗、靶向治疗)均可导致短期或长期心血管并发症,其中心肌损伤所致心功能不全和心力衰竭是最常见的心血管并发症之一,严重影响患者预后,已引起临床上的高度重视[1]。     

Hemodynamic effects of microbubble echo contrast

The dose-related hemodynamic effects of an active (bubble-rich) echo contrast agent were compared with those of a bubble-free contrast agent and saline solution to determine whether the microbubbles contained in the echo contrast agent are truly passive indicators in the circulation or whether they actively alter the hemodynamic state independent of the volume and osmotic loading associated with such injections. The study population consisted of 13 fully instrumented open-chest mongrel dogs. Four hundred ninety-two bolus injections were made of three different types: active contrast agent (Levovist, Schering AG, Berlin) (n = 333), saline solution (n = 112), and bubble-free contrast agent (n = 47). Levovist was administered in five dose ranges spanning 0.013 to 0.341 gm/kg and, like the saline solution, was administered in bolus volumes of 0.053 to 1.136 ml/kg. For each injection type, the percent change in hemodynamic parameters after administration of the bolus were calculated on the basis of the dose or volume of the injectate. Audio Doppler signal intensity was used to document the presence of bubbles in the injectate. Statistical significance was defined at the p = 0.05 level; clinical significance was defined as a greater than 15% change in a hemodynamic parameter. Statistically, but not clinically, significant changes were noted in almost all hemodynamic parameters regardless of injection type, and at all dose and volume ranges. Although statistically significant, injection of an active contrast agent in the human dose range resulted in a <5% change in hemodynamic parameters. High doses of a contrast agent (active or bubble-free) increased the left atrial pressure and had associated changes in peripheral vascular hemodynamics because of the osmotic load. Clinically significant increases (>15%) in pulmonary artery pressure and pulmonary vascular resistance were unique to the active contrast agent at high dose ranges. Standard doses of the active contrast agent changed the hemodynamics by less than 5% in healthy dogs. Transient clinically significant increases in pulmonary artery pressure and pulmonary vascular resistance are a unique side effect to high dose bolus injections of microbubble echo contrast agent.     

Transesophageal echocardiography: expanding indications for ICU use. How TEE can complement--or surpass--transthoracic techniques

Transesophageal echocardiography (TEE) is a Doppler technique that uses the esophagus as an acoustic window. In critically ill patients (particularly ventilated patients), TEE may be used to assess left ventricular function, valvular disease, endocarditis, and prosthetic valve dysfunction. It is also helpful in elucidating the cause of hypotension after cardiac surgery, and can detect chronic aortic dissection and transection, valve rupture, and myocardial contusion in trauma victims. TEE is superior to transthoracic echocardiography in evaluating a cardiac source of embolism. Contraindications to TEE include esophageal disorders and an uncorrected bleeding diathesis; a large hiatal hernia may cause suboptimal transgastric images.     

Neurologic monitoring in the ICU

While structure of the central nervous system (CNS) is evaluated through diagnostic tests such as computed tomography or magnetic resonance imaging, CNS function requires special monitoring techniques. These techniques are particularly useful adjuncts to the clinical examination, especially in the critically ill patient. Monitoring techniques include intracranial pressure monitoring, cerebral blood flow monitoring, cerebral hemodynamic assessment, and electrophysiologic monitoring. Rationale and specific applications are unique to each technique. Nursing considerations focus on knowledge of rationale for monitoring, providing safe patient care, validating appropriateness of interventions based on monitoring, and investigating the relationship of monitoring to outcome.     

Hemodynamic monitoring in childhood

Hemodynamic monitoring is indicated in children with impending or manifest cardiocirculatory failure. Since cardiocirculatory failure is characterized by an imbalance between oxygen delivery and oxygen demand due to perfusion failure, the parameters monitored should aid in the assessment of these oxygen variables. Oxygen delivery depends on oxygen content and cardiac output. Cardiac output is determined by heart rate and stroke volume; stroke volume by preload, afterload and contractility. Since the direct measurement of oxygen consumption routinely is almost impossible, global oxygen utilization represented by mixed venous oxygen saturation may be used to quantify the relationship between oxygen delivery and oxygen consumption. Justification of invasive hemodynamic monitoring depends among other things on an optimal balance between usefulness of information and complications associated with the techniques used. In future, the development of further noninvasive techniques and the scientific evaluation of recommended monitoring techniques are prospects in cardiovascular monitoring in childhood.     

Hemodynamic monitoring in childhood

Hemodynamic monitoring is indicated in children with impending or manifest cardiocirculatory failure. Since cardiocirculatory failure is characterized by an imbalance between oxygen delivery and oxygen demand due to perfusion failure, the parameters monitored should aid in the assessment of these oxygen variables. Oxygen delivery depends on oxygen content and cardiac output. Cardiac output is determined by heart rate and stroke volume; stroke volume by preload, afterload and contractility. Since the direct measurement of oxygen consumption routinely is almost impossible, global oxygen utilization represented by mixed venous oxygen saturation may be used to quantify the relationship between oxygen delivery and oxygen consumption. Justification of invasive hemodynamic monitoring depends among other things on an optimal balance between usefulness of information and complications associated with the techniques used. In future, the development of further noninvasive techniques and the scientific evaluation of recommended monitoring techniques are prospects in cardiovascular monitoring in childhood.     

Hemodynamic monitoring in sepsis

Arterial waveform analysis that does not require continuous calibration, impedance cardiography, electrical cardiometry, velocity-encoded phase contrast magnetic resonance imaging (MRI), pulsed dye densitometry, noninvasive pulse pressure analysis using tonometry, suprasternal Doppler, partial CO2 rebreathing techniques, and transcutaneous Doppler are just some of the other emerging technologies not described in this review that may be used routinely in the management of sepsis and septic shock in the very near future. These innovative approaches may further increase our ability to optimize patients' fluid status and hemodynamics. We also have ability to monitor the microcirculation. This increasingly sophisticated approach to the management of sepsis and septic shock will hopefully translate into better patient outcomes. However, optimal use of any hemodynamic monitoring requires an understanding of its physiologic underpinnings. Accurate interpretation of the hemodynamic information coupled with a protocolized management algorithm is the cornerstone of an effective resuscitation effort. Many forms of hemodynamic monitoring have emerged over the past 20 to 30 years with no convincing evidence for the superiority of any single techniques (Table 2). The goal of hemodynamic monitoring and optimization is to combat the systemic imbalance between tissue oxygen supply and demand ranging from global tissue hypoxia to overt shock and multiorgan failure. It remains unproven that hemodynamic monitoring of disease progression can effectively change patient outcome. However, despite our increased understanding of sepsis pathophysiology, mortality and morbidity from the disease remains high. Therefore, the search for the optimal parameters in resuscitation and the best way they can be monitored will continue.     

Hemodynamic monitoring in the operating room

Cardiopulmonary homeostasis for the high risk surgical patient is dependent on invasive monitoring techniques which are designed to allow for the early detection of physiological dysfunction during the development stages. One must maintain both minimum and maximum predetermined cardiorespiratory values by the early utilization of specific therapeutic intervention in order to counter the physiological deviation from the previously determined acceptable values.     

Clinical review: Hemodynamic monitoring in the intensive care unit

Since the beginning of modern anesthesia, in 1846, the anesthetist has relied on his natural senses to monitor the patient, aided more recently by simple technical devices such as the stethoscope. There has been a tremendous increase in the availability of monitoring devices in the past 30 years. Modern technology has provided a large number of sophisticated monitors and therapeutic instruments, particularly in the past decade. Most of these techniques have enhanced our understanding of the mechanism of the patients' decompensation and have helped to guide appropriate therapeutic interventions. As surgery and critical care medicine have developed rapidly, patient monitoring capability has become increasingly complex. The most important aspect in monitoring the critically ill patient is the detection of life-threatening derangements of vital functions. Aggressive marketing strategies have been promoted to monitor almost every aspect of the patient's status. However, these strategies are only telling us what is possible; they do not tell us whether they enhance patient safety, improve our therapy, or even improve patient outcome.     

Nutritional monitoring in the ICU: rational and practical application

The metabolic response to injury can induce a state of hypermetabolism that results in the rapid loss of the body nitrogen, so that a critical reduction in lean body mass that affects morbidity and mortality can occur in a short period of time. The process also induces a redistribution of the body nitrogen away from the skeletal mass and toward the viscera and areas of increased metabolic activity, such as the surgical wound, the zone of inflammation, and toward cells producing mediators. Exogenously administered nitrogen is not very effective in reducing the rate of catabolism. It can, however, increase the rate of protein synthesis. In so doing, the rate of net catabolism is reduced. The modified amino acids appear to be much more effective in achieving these ends than do the standard amino acid formulas. Visceral protein synthesis is difficult to use as an index of visceral protein malnutrition in the settings where the metabolic response to injury is also present. These proteins and the acute-phase reactants may not have the sensitivity and specificity to discriminate between visceral protein malnutrition and the changes induced by the metabolic response to injury. The practical clinical endpoint, then, in managing the nitrogen economy during the metabolic response to injury is to provide adequate nitrogen intake, achieving 2 to 4 gm of positive nitrogen balance whenever possible. Caloric (energy) equilibrium can be achieved. Calories in excess of demand or glucose in excess of the ability to effectively oxidize, however, can have detrimental effects in some settings. Expired gas analysis can be useful in this context. Achieving caloric equilibrium does not appear to be essential. The reduction in malnutrition as a cofactor in morbidity and mortality appears to come from achieving nitrogen equilibrium. These alterations in metabolism induced by metabolic stress and the changes in nutrient requirements have been called metabolic support and are summarized in Table 3. The end-points of metabolic support, whenever possible, become 2 to 4 gm of positive nitrogen balance with an amino acid load that will achieve that balance; support of visceral protein synthesis as judged by acute-phase reactant and hepatic protein (e.g., transferrin) synthesis; and avoiding complications of excess VCO2 and urea production (BUN less than 110 mg per cent) (Fig. 5).     

Extubation in ICU: enhancing the nursing role.

UKCC guidance gives a clear framework within which nurses can enhance their practice. Enhanced nurses can extubate patients with appropriate training and suitable protocols. Cost-effective, high-quality care can be provided by nurses working to the best of their professional knowledge and skill.     

Hemodynamic monitoring in respiratory care.

Continuous, invasive hemodynamic monitoring of patients in respiratory failure is an important aspect of total respiratory care. Understanding both the technical and physiological principles underlying hemodynamic monitoring is therefore important for respiratory care practitioners. This review is designed to meet this need by (1) addressing the technical aspects of hemodynamic monitoring (catheters, transducers, and monitors), (2) discussing the determinants of commonly measured hemodynamic variables (intravascular pressures and cardiac output), and (3) offering an orderly approach to hemodynamic data that allows for rapid determination of the patient's physiologic state and appropriate diagnostic possibilities. These principles are illustrated by five examples.     

Hemodynamic monitoring in postanesthesia care units

Sophisticated practice modalities, advances in technology, and the increase of sicker and older patients undergoing surgery mandate an expansion of all PACU nurses' skill and knowledge base. Invasive hemodynamic monitoring, as well as the quantitative assessment of cardiovascular function that it provides, is both feasible and necessary as an adjunct tool in today's PACU. Hemodynamic monitoring should be used only when a specific management decision is being considered and when the physician is committed to act on the data obtained. Once instituted, it is the nurse's responsibility to care for the patient safely and provide accurate and reliable data for collaborative assessment.