AACN clinical issues in critical care nursing
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AACN Clin Issues Crit Care Nurs · May 1993
Review Case ReportsHypothermia and rewarming after cardiac surgery.
Ensuring adequate oxygen delivery to the tissues with respect to oxygen demand is an important operative challenge during cardiac surgery. The state of the art in myocardial preservation in the 1990s has evolved to include pretreatment of the myocardium; intraoperative use of systemic hypothermia with cardiopulmonary bypass (CPB), topical cooling of the myocardium, cold cardioplegia, and myocardial reperfusion; and postoperative oxygen transport support. ⋯ Appropriate temperature monitoring and reporting support timely medical and nursing interventions for hypothermia, such as internal and external rewarming techniques or drug administration to facilitate the rewarming process and suppress or treat shivering. This article addresses the physiologic condition of hypothermia, the elective hypothermia techniques used during cardiac surgery, and the medical or nursing rewarming and management techniques for the postoperative cardiac surgery patient.
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A recent national survey of critical care nurses reveals that the leads many nurses select to monitor their patients are diagnostically inferior to other available leads, and that lead placement often is inaccurate. This article reviews the best leads for electrocardiographic (ECG) monitoring, illustrates their accurate placement, and explains reasons for the dilemma in current practice. Questions relevant to practicing nurses are addressed, including 1) Is lead MCL1 as good as V1? 2) When is it appropriate to substitute lead MCL1 for V1? and 3) How important is it for electrodes to be placed exactly in specific anatomic locations? Finally, a case study is provided to illustrate how accurate monitoring can prevent misdiagnosis and resultant inappropriate therapy.
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The goal of invasive hemodynamic monitoring is to evaluate the components of oxygen delivery and consumption. Parameters obtained from the physiologic profile are used to assess and optimize oxygen delivery to meet the tissue needs of the critically ill patient. Oxygen delivery is defined as cardiac output multiplied by the arterial oxygen content. ⋯ Current clinical issues are directed toward assessment of the patient's status in relation to the oxygen supply-and-demand balance. Identification of therapeutic interventions to achieve the goal of increasing oxygen delivery are paramount. Evaluation of the role of the right ventricle (RV) in biventricular performance and incorporation of volumetric measurements to assess the critically ill patient are presented.
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AACN Clin Issues Crit Care Nurs · Feb 1993
Using continuous SVO2 to assess oxygen supply/demand balance in the critically ill patient.
To ensure that tissues are well oxygenated, oxygen supply and demand are now targets of therapy for the critically ill patient. This chapter reviews the physiologic determinants of oxygen supply, how it is threatened by respiratory or cardiac dysfunction or by hemorrhaged or anemic states, and how it can be assessed in individual patients. ⋯ Failure of tissues to consume enough oxygen is explained in patients with critically low delivery or with the maldistributed blood flow state seen in sepsis. The monitoring of mixed venous oxygen saturation is examined as a method of tracking the threats to supply/demand balance and of guiding treatment that can support the adequate oxygenation of tissue.
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Many patients in the critical care unit (CCU) are at risk for myocardial ischemia and acute coronary artery reocclusion. The use of continuous ST segment monitoring detects transient and sustained ischemia, despite the absence of symptoms, more completely than rate and rhythm monitoring alone. ⋯ Thus, when using ST segment monitoring for detection of ischemia, one of the most important decisions for the nurse to make is lead selection. In addition, both ischemic and nonischemic ST segment changes must be considered.