Biomedical subjects

David J Powner

Publications and source records attributed to David J Powner.

At least 19 recordsLinked to original sources

PubMed2006

Cardiac dysrhythmias during donor care.

Organ procurement coordinators must treat various cardiac dysrhythmias (arrhythmias), including rhythm disturbances that may cause or follow a cardiac arrest, in about 15% to 50% of donors. Treatment decisions should be based on the particular dysrhythmia and its effect on donor blood pressure. Medications selected should be effective but short acting. In this article, data available in publications located through a PubMed search are reviewed and specific dysrhythmias that are likely to occur during donor care are described. Treatment recommendations are based on guidelines from the American Heart Association.

Anti-Arrhythmia Agents↗

PubMed2006

Advanced practice organ procurement techniques: insertion of central venous catheters.

Placement of central venous catheters by organ procurement coordinators to assist in obtaining blood samples or for measuring intravascular pressure is appropriate. Preparation for this role should include appropriate didactic instruction and supervised clinical experience. The organ procurement organization must ensure that such training occurs and must support a continuing quality assurance program for such providers. Policies and procedures must be provided to guide practitioners in site selection, timing of implementation, and titration of measurements obtained. Also, resources must be readily available to treat any complications. This discussion reviews methods for insertion of venous catheters placed in the femoral, internal jugular, or subclavian veins.

Catheterization, Central Venous↗

PubMed2006

Advanced practice organ procurement techniques: insertion of arterial catheters.

Placement of arterial catheters by organ procurement coordinators is becoming more common. Classroom and clinical training in this technique and provision of appropriate quality assurance and supportive policies/procedures by organ procurement programs will ensure the coordinators' success. This discussion reviews technical aspects of insertion of catheters into the radial, femoral, and axillary arteries, potential complications, and alternative noninvasive methods of measuring blood pressure.

Blood Pressure Determination↗

PubMed2006

Endocrine failure after traumatic brain injury in adults.

OBJECTIVE: To review histopathological and clinical data linking endocrine failure to traumatic brain injury (TBI) during acute neurosurgical treatment and rehabilitation. METHODS: A focused search of the Medline (PubMed) medical literature database and the authors' files were used to identify selected publications. RESULTS: Endocrine failure may produce clinically important consequences during acute and convalescent care after TBI, and may be caused by direct injury to the hypothalamic- pituitary axis (HPA), neuroendocrinological effects from catecholamines and cytokines, or from systemic infection/inflammation that produces primary gland failure. Autopsy evidence of hemorrhage or ischemia in the HPA is common soon after TBI. The estimated incidence of acute hormone reduction is adrenal 15%, thyroid 5 - 15%, growth hormone 18%, vasopressin 3 - 37%, and gonadal (25 - 80%). Hyperprolactinemia occurs in more than 50% of patients. Inappropriate secretion of antidiuretic hormone (SIADH) and the euthyroid sick syndrome are common. Acute adrenal failure, central hypothyroidism, SIADH, and diabetes insipidus (DI) may cause poor neurological outcomes including death, hypo/hypernatremia, hypotension, and increased vasoactive drug requirements. Treatment of those conditions is warranted. Delayed diagnosis of hypopituitarism is often mistaken for symptoms of residual head injury. Some chronic hormone deficiency occurs in 30 - 40% of selected patients after TBI, more than one deficiency in 10 - 15%, growth hormone in 15 - 20%, gonadal hormones in 15%, and hypothyroidism in 10 - 30%. Chronic adrenal failure and DI are reported over a wide incidence. Prolactin is elevated in 30%. All clinical symptoms respond favorably to replacement therapy. CONCLUSIONS: Severe TBI associated with basilar skull fracture, hypothalamic edema, prolonged unresponsiveness, hyponatremia, and/or hypotension is associated with a higher occurrence of endocrinopathy. Greater awareness of this possible complication of TBI and appropriate testing are encouraged.

Adrenal Insufficiency↗

PubMed2005

Donor care before pancreatic tissue transplantation.

Publications are reviewed to identify factors related to donor care that may optimize the function of pancreatic tissue (whole or segmental organ or islet cells) after transplantation. Short cold ischemia time, avoidance of hypotension, and treatment of donor hyperglycemia appear to be beneficial, although additional properly designed studies are needed to verify those findings.

Age Factors↗

PubMed2005

Interventions during donor care before lung transplantation.

Improvement in the ratio of PaO2 to the fraction of inspired oxygen and treatment of pulmonary infections in donors have been cited as important goals for improving lungs before implantation and restoring marginal lungs to the donor pool. Likewise, improving donor PaO2 is often critical for other organs during donor care. The common physiological mechanisms responsible for hypoxemia are ventilation/perfusion mismatching, abnormal oxygen diffusion, and hypoventilation. These mechanisms are discussed and treatment options are considered.

Apnea↗

PubMed2005

A review of thyroid hormone administration during adult donor care.

Serum concentrations of thyroid hormones tetraiodothyronine and triiodothyronine commonly are low after head injury and brain death. Thyroid hormone replacement therapy, however, is a controversial part of donor management. This article reviews publications in which thyroid hormone administration was evaluated in human donors. A classification of the "quality" of study methods used in those publications is presented as part of the data review. No publications support the routine administration of thyroid hormone for all donors. "Rescue" replacement in support of cardiac inotropic function is supported by some studies, but the experimental design of those investigations is not optimal. Thyroid hormone replacement and its dosing should be decided by organ procurement organizations as part of treatment protocols.

Adult↗

PubMed2005

Variables during care of adult donors that can influence outcomes of kidney transplantation.

Publications that relate characteristics of donors to renal function of recipients are reviewed. Most publications report retrospective observations that relate outcomes to donor variables that cannot be altered during donor care. Factors that can be altered in adult donors in an effort to improve recipients' outcomes include urine output and creatinine level. Increasing urine output to more than 100 mL/h, at least during the hour before explantation, and returning the creatinine level to match its serum concentration when the patient was admitted can improve outcomes. Ways of accomplishing those goals during donor care are discussed, with emphasis on support of renal blood flow.

Adult↗

PubMed2005

Treatment goals during care of adult donors that can influence outcomes of heart transplantation.

Myocardial dysfunction during care of adult donors can result from injury occurring before hospital admission or during the progression of brain death. Few evidence-based data correlate specific hemodynamic goals during donor care with outcomes of heart transplantation, although many recommendations exist. Spontaneous reversal of early heart damage or correction of poor cardiac performance can yield outcomes equivalent to outcomes in recipients who had ideal donors. Hemodynamic goals developed in the operating room can be applied in intensive care to improve outcomes of transplantation. These goals include maintenance of mean arterial pressure greater than 60 mm Hg, central venous pressure less than 12 mm Hg, cardiac output greater than 3.8 L/min, cardiac index greater than 2.1, and systemic vascular resistance between 800 and 1200 dyne x sec x cm(-5). The ejection fraction and other echocardiographic data also provide helpful guidance when determining whether a heart is suitable for transplantation and during therapy. Titration of cardiovascular variables often requires invasive monitoring to ensure that cardiac preload, afterload, and contractility are optimal.

Adult↗

PubMed2005

Introduction to the interpretation of chest radiographs during donor care.

Organ procurement coordinators often provide independent interpretations of chest radiographs during donor care. Catheter or tube position, lobar atelectasis, extra-alveolar air, air bronchograms, pleural fluid, and other findings are important throughout donor care and when deciding if a lung is acceptable for transplantation. Technical factors, features of a normal chest radiograph, and abnormal radiographic findings are reviewed and examples are presented.

Artifacts↗

PubMed2005

Counteracting the effects of anticoagulants and antiplatelet agents during neurosurgical emergencies.

OBJECTIVE: Emergent neurosurgery may be precipitated or complicated by previous or concomitant administration of anticoagulants, thrombolytic medications, or antiplatelet agents. Recommendations are presented to reverse or counteract the effects of those drugs before or during neurosurgical interventions. METHODS: Directed literature review. RESULTS: Evidence-based data specific to neurosurgery are limited. CONCLUSION: Other clinical experience based on mechanisms of drug action within the coagulation process confirm that single or combined administration of platelet transfusions, fresh frozen plasma, cryoprecipitate, vitamin K, protamine, desmopressin, and recombinant activated factor VII can treat coagulopathies caused by warfarin, heparin, aspirin, adenosine diphosphate-receptor antagonist, glycoprotein IIb/IIIa receptor blocking agents, and thrombolysis. Specific interventions and recommended dosages are reviewed.

Anticoagulants↗

PubMed2004

Therapeutic hypertension: principles and methods.

The aspects of cardiovascular physiology important for the safe and effective implementation and titration of hypertensive therapy among neurosurgical patients with neurological or neurosurgical illness/injury are reviewed. Therapeutic hypertension may be an appropriate treatment for some neurological or neurosurgical conditions, e.g., vasospasm or support of cerebral perfusion pressure. Initiation and maintenance of hypertension should be done safely to avoid complications and/or undesired side effects. Accurate measurement of the arterial and central vascular pressures, the limitations of those methods, and alternative estimates of intravascular volume are reviewed. Hypertensive therapy is accomplished by modifying cardiac output and systemic vascular resistance, the principal physiological determinants of blood pressure. The goals of hypertensive therapy can be achieved by proper evaluation and manipulation of the four components of cardiac output, preload, afterload, heart rate and contractility. Measurement or calculation of estimates of these parameters is important in the selection of proper medications or supplemental fluid administration.

Brain Diseases↗

PubMed2004

Cardiopulmonary resuscitation and somatic support of the pregnant patient.

Cardiopulmonary arrest during pregnancy is a rare event that critical care clinicians must be prepared to manage. The causes of cardiopulmonary arrest during pregnancy, recommended modifications to cardiopulmonary resuscitation protocols that are specific to pregnancy, indications for and timing of perimortem cesarean delivery, and the expected fetal outcomes are reviewed. Rarely, brain death of a pregnant patient may occur in which continued support of the mother is possible to prolong the pregnancy and improve fetal outcome. Prolonged somatic support of pregnant patients who are brain dead presents specific management challenges, but has been accomplished. The physiologic changes that occur after brain death and recommendations for somatic support of the brain dead pregnant patient also are reviewed.

Brain Death↗

PubMed2004

Variability among hospital policies for determining brain death in adults.

OBJECTIVE: In the absence of federal requirements or state statutes, criteria to certify brain death are specified by medical staff and administrative policies in individual hospitals. Variability among such policies may allow inconsistency in the declaration of death by neurologic criteria. Our intent was to partially quantify diversity among hospital standards used in brain death certification. DESIGN: Survey. SETTING: Six hundred randomly selected hospitals. PATIENTS: None. INTERVENTIONS: A survey was conducted of 600 hospitals randomly selected from the American Hospital Association registry representing 200 hospitals each of <300 beds, 300-500 beds, and >500 beds. One hundred six policies submitted by these institutions comprised the final study group. Policies were reviewed for criteria of interest and were compared against variables recommended by the American Academy of Neurology. MEASUREMENTS AND MAIN RESULTS: Significant variability in policy criteria was found compared with the American Academy of Neurology and other authoritative standards. Differences were greatest in specifying conditions to be excluded before testing and in specific testing methods during a detailed physical examination. The few differences noted between larger vs. smaller hospitals most likely reflect greater availability of resources in larger institutions. CONCLUSIONS: Differences among hospital policies for certification of brain death may permit variability among hospitals throughout the United States in the pronouncement of death by neurologic criteria. Standardization and enforcement of policies that ensure the highest possible accuracy should be considered.

Adult↗

PubMed2004

Proposed treatment guidelines for donor care.

The complex care of the organ donor during preparation for organ removal and provision of the best organs for transplantation is often the responsibility of the organ procurement coordinator. To assist in that process the following clinical problem-based guidelines have been developed. A standard order set is recommended to initiate treatment and to provide a continuing laboratory database. As clinical concerns arise from that database, past medical history, or ongoing donor care, section of these guidelines may serve as references for specific interventions. Physician consultation and collaboration with other bedside care providers are encouraged throughout.

Algorithms↗

PubMed2004

Factors during donor care that may affect liver transplantation outcome.

Publications are reviewed that identify factors during donor care and characteristics of the donor liver that may be associated with outcome following liver transplantation. The procurement coordinator has the opportunity to influence cold ischemia time, blood pressure, the serum sodium concentration and, perhaps, liver glycogen reserves. These variables may significantly affect postimplantation graft performance and graft or recipient survival. Summaries of those publications comprising this database are presented, and several limitations in their interpretation are discussed.

Age Factors↗

PubMed2003

Extended somatic support for pregnant women after brain death.

OBJECTIVE: To review case reports of pregnant women who have been supported after brain death until successful delivery of their infants. From these reports and other literature about brain death, normal physiologic changes of pregnancy, and specific needs for fetal development, recommendations were made to assist in supporting pregnant women after brain death until delivery of a mature fetus who is likely to survive. DATA SOURCES: Personal files and experiences, MEDLINE review of case reports and publications about physiologic changes present during normal pregnancy and after brain death, and the critical needs for fetal development were included. DATA EXTRACTION: Eleven reports of ten patients comprise the accumulated clinical experience. Hypotension, requiring fluid administration and inotropic/vasopressor therapy, occurred in all the mothers, and in six cases, was the reason for urgent delivery. The longest period of support was 107 days, from 15 to 32 wks of gestation. Two mothers also became organ donors. Recurrent infections, thermolability, and other complications common to prolonged ICU care were encountered. All infants survived. One had congenital abnormalities caused by phenytoin use by the mother. When followed, all others developed within normal growth and mental variables. These cases plus literature citations noted above were used to develop recommendations for maternal/fetal care. CONCLUSION: Preservation of uterine/placental blood flow is the most important priority during somatic support. Imprecise autoregulation of the uterine vasculature during maternal hypoxemia or hypotension makes this goal a significant challenge. Special considerations for nutrition; medication use; cardiovascular, respiratory, or endocrine therapy; fetal monitoring; hormone replacement; and ethical concerns are discussed.

Brain Death↗

PubMed2003

Effects of gene induction and cytokine production in donor care.

Gene induction, cytokine production, and programmed neuronal and myocardial cell death are concerns that have entered the areas of donor evaluation and care over the past several years. Following ischemic or traumatic brain injury and the evolution of brain death, a large number of proteins (cytokines) are produced as part of a regional inflammatory response. These cytokines and related compounds appear to contribute to programmed death (apoptosis) of individual cells and the severe cardiac and hemodynamic changes often encountered during donor care. In addition, these cytokines and related compounds may sensitize donor organs so that a faster and more severe form of rejection occurs in the recipient. Although no directed therapy for these cytokine effects is presently available, the organ procurement coordinator should be aware of these issues and concerns as new treatment options evolve in the near future.

Apoptosis↗