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Biomedical subjects

T Ahrens

Publications and source records attributed to T Ahrens.

At least 37 records · Page 2Linked to original sources
PubMed1998

Activation-dependent modulation of hyaluronate-receptor expression and of hyaluronate-avidity by human monocytes.

During inflammation, activated monocytes (Mo) migrate into tissues where they interact with extracellular matrix components such as hyaluronate (HA), produced in high amounts at inflammatory sites. We determined whether Mo that had invaded sites of cutaneous inflammation bind HA and express the putative HA receptors CD44 isoforms, ICAM-1, or receptor for hyaluronate-mediated motility (RHAMM). In cutaneous inflammation, activated infiltrating Mo displayed high HA avidity and expressed epitopes encoded by CD44s, CD44 variant exons v3, v4, v5, v6, v7, and v9, and ICAM-1, but not RHAMM. We further investigated how activation affects the avidity of Mo for HA and which receptors were responsible for such binding. Mo freshly purified from human peripheral blood bound little HA and expressed CD44s but no epitopes encoded by CD44v exons, ICAM-1, or RHAMM. During short-term tissue culture, Mo upregulated their HA avidity and expression of ICAM-1, CD44s, and epitopes encoded by CD44v, all of which were further augmented by IFN-gamma or lipopolysaccharide, whereas RHAMM was not detectable. Thus in vitro activated Mo resembled Mo that had migrated to inflammatory sites in vivo. Lipolysaccharide or IFN-gamma-induced HA binding was inhibited by more than 90% with monoclonal antibodies directed against N-terminal HA binding domains of CD44s, but not by monoclonal antibodies against CD44v epitopes or ICAM-1. In conclusion, we show that upon in vitro or in vivo activation, Mo enhance their capacity to bind HA. This is critically dependent upon the expression ofCD44s epitopes. Regulated CD44-HA interactions may be important for the ability of Mo to migrate into and within sites of inflammation and for Mo effector functions.

Humans↗
PubMed1998

Technology utilization in the cardiac surgical patient: SvO2 and capnography monitoring.

Technology utilization in the cardiac surgical patient has proliferated, despite a lack of evidence that the technology has a positive impact on patient outcomes. Hospitals are left to their own efforts in deciding how and what technology to use. The result is an inconsistent use of technology. The use of structured guidelines can help hospitals improve the use of technology. Two controversial technologies, capnography and mixed venous oxygen saturation monitoring, are analyzed using this approach. It is essential for hospitals to support clinicians as they use methods in the evaluation and implementation of technology. Technology alone will not improve patient outcome or control costs.

Capnography↗
PubMed1998

Utilization of intensive care unit technology.

Technology utilization in acute and critical care holds great promise for improving the management and outcome of patients. However, before this promise can be realized, technology has to be properly evaluated for appropriateness of use. This evaluation must include both the clinical impact on patient outcomes as well as the economic impact. Following this initial evaluation, for technologies deemed appropriate for use, careful preparation of clinicians in the use of the technology is necessary. Education must prioritize how the technology is to be used as well as provide incentives for the clinicians to change their current practice. If these three key steps are followed, technology can achieve the promise of improving patient management and outcome. Unfortunately, evidence exists which suggests that these three steps are not followed in many, if not most, hospitals in the United States. In this article, a method of implementing these three steps is presented. However, it is essential that national organizations and societies become active in this process, lest widespread variation in technology utilization continue.

Attitude of Health Personnel↗
PubMed1998

Impact of technology on costs and patient outcome.

Technology is only as effective as the clinicians who employ the technology and the system in which they function. For any technology to change patient outcome, or be cost effective, clinicians must be educated and incented to change their practice. At this point in American health care, technology appears to vary widely in the effectiveness in which it is employed. Research consistently decries the lack of effective use of technology. Some authors have claimed this lack of consistent use of technology is near a crisis proportion, both in terms of the costs and impact on patient outcome. The wide variability in technology application is understandable owing to the lack of a unifying approach to the application, education, and evaluation of technology. Only when we have an organized system, lead by professional societies, will technology usage achieve standardization. Until that time, individual hospitals need to follow guidelines like the ones presented in this article to ensure patients are receiving optimal and cost-effective care.

Critical Care↗
PubMed1995

Frequency requirements for zeroing transducers in hemodynamic monitoring.

BACKGROUND: Accurate hemodynamic monitoring information can be obtained only if the transducer/amplifier system is used correctly. One major component of correct use is zeroing the transducer to provide a relative reference point on which to measure hemodynamic pressures. However, nursing requirements for frequency of zeroing are inconsistent. In addition, the concepts of leveling and zeroing are frequently confused. OBJECTIVE: To determine whether transducers drift from zero (+/- 2 mm Hg), and if they do not drift from zero, how long they hold a zero value. METHODS: The study, conducted in four midwestern hospitals, was carried out in two parts: an initial 10-day bench test of 50 transducers and an evaluation of 388 transducers attached to patients for 1 to 5 days. Transducers were monitored over time after being consistently leveled. RESULTS: Bench testing indicated that 100% of transducers did not drift +/- 2 mm Hg from zero during the study period. In the clinical study, only 1.3% of transducers drifted from zero. Five transducers drifted +/- 2 mm Hg from zero, with a range of -5 to 3 mm Hg. CONCLUSIONS: We conclude that transducers used for hemodynamic monitoring require zeroing only on initial setup and disconnection from the amplifier.

Calibration↗
PubMed1994

Pulmonary complications of trauma.

Pulmonary complications can be the result of direct chest trauma or can occur from indirect trauma outside of the thorax. Understanding the mechanism of pulmonary function in determining intrapulmonary shunt and physiologic deadspace can assist the clinician in assessing the severity and monitoring the progression of pulmonary injury in patients. This article reviews assessment parameters, physiology, and treatment of direct and indirect pulmonary trauma.

Contusions↗
PubMed1993

Changing perspectives in the assessment of oxygenation.

Changing the perspective of clinical assessment to cellular oxygenation assessment will be a trend in the 1990s, particularly with the development of new technologies. New technologies such as MRI and PET scanning will increase clinicians' ability to assess cellular dysfunction and oxygenation disturbances. Because of improved technology, the focus in assessing oxygenation of the critically ill also will change. Critical care clinicians must accurately identify whether arterial or cellular oxygenation is being assessed. Arterial oxygenation problems are usually a reflection of a loss of hemoglobin or deteriorating lung function (through increased intrapulmonary shunting). Cellular oxygenation problems are more related to the relationship between oxygen delivery and cellular utilization of oxygen. In most critical care situations, cellular oxygenation is the aspect of oxygenation that is of most interest. The more familiar the clinician is with the role oxygen plays in cellular metabolism, the more meaningful the oxygenation assessment becomes. Common nursing techniques for the assessment of oxygenation (eg, physical assessment, blood gases and pulse oximetry) still have a place, but their limited accuracy must be kept in perspective when assessing cellular oxygenation.

Cell Hypoxia↗
PubMed1993

Respiratory monitoring in critical care.

The assessment of pulmonary function, from a clinical perspective, can be performed accurately only if the clinician understands the concept ventilation/perfusion ratios of the lung. The major categories of ventilation/perfusion ratios are intrapulmonary shunting and physiologic deadspace. Virtually all pulmonary assessments and interventions are aimed to address Qs/Qt or Vd/Vt. This chapter provides background information useful to the clinician in the assessment of intrapulmonary shunting and deadspace analysis. From this information, more thorough assessments of pulmonary function are possible.

Blood Gas Analysis↗
PubMed1992

Nurse clinician model of managed care.

Many different models of delivering nursing care have been proposed, each with specific advantages and disadvantages. One such model, the nurse clinician model, uses the strengths of advanced clinical practice as the cornerstone for improving quality in patient care. The increase in quality simultaneously produces an efficient and cost-effective system, as indicated by the results of a multiyear study at our institution. While other effective models exist, those that emphasize advanced clinical practice, such as the nurse clinician model, are most likely to achieve improved patient outcomes and conserve resource expenditures.

Humans↗
PubMed1992

Pulmonary critical care. Airway pressure measurement as an aid to identify end-expiration in hemodynamic waveform analysis.

The value of airway pressure monitoring is the improved clarity in identifying end-expiration. Short of monitoring intrapleural pressures, airway pressure monitoring has the potential to give the most accurate method for identifying the correct respiratory point to read hemodynamic values. Airway pressure monitoring can improve the reliability of hemodynamic waveform analysis between nurses and reduce some of the subjectivity associated with hemodynamic waveform analysis.

Critical Care↗