Search PubMed⌕ Search

Biomedical subjects

B A Shapiro

Publications and source records attributed to B A Shapiro.

At least 37 records · Page 2Linked to original sources
PubMed1996

Evaluation of an on-demand, ex vivo bedside blood gas monitor on pulmonary artery blood gas determinations.

Critically ill patients often have cardiopulmonary perturbations that require rapid and frequent assessment for optimal care, including cardiac output determinations, measurement of cardiac filling pressures, and arterial and mixed venous blood gas determinations. We evaluated the performance of a rapid, on-demand bedside blood gas monitor to determine arterial and mixed venous blood gas values. The blood gas monitor uses fluorescent optode technology to directly measure Po2, Pco2, and pH. This measurement is accomplished by aspirating blood from the artery or vein into a sampling chamber where it interfaces with the fluorescent optode. After approximately 90 s of equilibration, the blood gas values are reported. Since the blood is drawn into the sampling chamber, it can be returned to the patient, thus eliminating the need for phlebotomy. We studied 15 critically ill patients requiring systemic and pulmonary arterial catheterization. Conventional blood gas analysis was performed simultaneously. The results obtained from the blood gas monitor were compared with those obtained via traditional blood gas analysis using Bland-Altman plots and examination of bias and precision. The results were well within the expected clinical variance. During the study period, there was no interference with patient care or adverse events related to the use of the monitoring system. In conclusion, the blood gas monitor can provide rapid, accurate determinations of arterial and mixed venous blood gases allowing optimal therapeutic interventions in critically ill patients.

Adult↗
PubMed1996

Microbial contamination of blood conservation devices during routine use in the critical care setting: results of a prospective, randomized trial.

OBJECTIVES: To compare microbial contamination of two different blood conservation devices; to determine if there was an association between contamination of the blood conservation devices and clinical infections; to determine if there was a significant user preference for either of the two devices. DESIGN: Prospective, randomized trial. SETTING: Medical, neurosurgical, and spinal cord intensive care units of an urban, university hospital. PATIENTS: Forty patients who required clinically indicated intrafierial catheters placed at new sites. INTERVENTIONS: The two most widely available blood conservation devices at the time of the study (Venous Arterial blood Management Protection system [VAMP], Baxter Edwards Critical-Care, Irvine, CA; and Safe Draw, Ohmeda, Madison, WI) were chosen for comparison. After the normal 48 to 72 hrs of device use, the blood conservation systems were removed and semi-quantitative and quantitative cultures were taken from comparable sites of the two devices. Positive cultures from the patients were recorded and correlated with cultures obtained from the devices. In order to assess preference for either device, a survey tool was administered to the nursing staff who participated in the study. MEASUREMENTS AND MAIN RESULTS: Quantitative cultures from all sites cultured in both groups demonstrated mean colony counts of < 10(3) colony-forming units (cfu)/mL. There were no statistically significant differences in the colony counts at any of the sites compared between the two groups. There were no statistically significant relationships between positive cultures and patient age, gender, duration of device utilization, frequency of device entry, or the intensive care unit in which the study was conducted. In no circumstance did positive cultures from any of the blood conservation devices correlate with positive culture results from any sites of clinical infection. The clinical survey demonstrated a statistically significant preference for the VAMP system, which persisted despite increased experience with the Safe Draw system. CONCLUSIONS: The levels of microbial contamination noted in these devices were not consistent with clinical infection (defined as 10(3) cfu/mL on quantitative cultures). There was no significant difference in degree or pattern of contamination between the two devices. When utilized and changed according to the Centers for Disease Control guidelines, blood conservation devices are not harbors of infection in the critical care setting. Blood conservation devices can be used as part of a comprehensive blood conservation program in the critical care setting without undue concern for exacerbating infectious processes.

Blood Specimen Collection↗
PubMed1995

Practice parameters for intravenous analgesia and sedation for adult patients in the intensive care unit: an executive summary. Society of Critical Care Medicine.

OBJECTIVE: The development of practice parameters for intravenous analgesia and sedation for adult patients in the intensive care unit (ICU) setting for the purpose of guiding clinical practice. PARTICIPANTS: A task force of more than 40 experts in disciplines related to the use of analgesic and sedative agents in the ICU was convened from the membership of the American College of Critical Care Medicine (ACCM) and the Society of Critical Care Medicine (SCCM). EVIDENCE: The task force members provided the personal experience and determined the published literature (MEDLINE articles, textbooks, pharmacopeias, etc.) from which consensus would be sought. Published literature was reviewed and classified into one of four predetermined categories, according to study design and scientific value. CONSENSUS PROCESS: The task force met several times as a whole, and numerous times in smaller groups by teleconference, over a 1-yr period to identify the pertinent literature and arrive at consensus recommendations for the whole task force to discuss. Consideration was given to the relationship between the weight of scientific information and the experts' viewpoints. Over the next year, draft documents were composed by a task force steering committee and debated by the task force members until consensus was reached by nominal group process. The task force draft was then reviewed, assessed, and edited by the Board of Regents of the ACCM. After steering committee approval, the draft document was reviewed and approved by the SCCM Council. DATA SYNTHESIS: To facilitate rapid communication of the six recommendations contained within the complete and unabridged practice parameter document, an executive summary was prepared for publication by the ACCM Board of Regents, and this executive summary was approved by the task force steering committee and the SCCM Executive Council. CONCLUSIONS: A consensus of experts provided six recommendations with supporting data for intravenous analgesia and sedation in the ICU setting: a) morphine sulfate is the preferred analgesic agent for critically ill patients; b) fentanyl is the preferred analgesic agent for critically ill patients with hemodynamic instability, for patients manifesting symptoms of histamine release with morphine, or morphine allergy; c) hydromorphone can serve as an acceptable alternative to morphine; d) midazolam or propofol are the preferred agents only for the short-term (< 24 hrs) treatment of anxiety in the critically ill adult; e) lorazepam is the preferred agent for the prolonged treatment of anxiety in the critically ill adult; f) haloperidol is the preferred agent for the treatment of delirium in the critically ill adult. This executive summary selectively presents supporting information and is not intended as a substitute for the complete document.

Adult↗
PubMed1995

Practice parameters for sustained neuromuscular blockade in the adult critically ill patient: an executive summary. Society of Critical Care Medicine.

OBJECTIVE: The development of practice parameters for achieving sustained neuromuscular blockade in the adult critically ill patient for the purpose of guiding clinical practice. PARTICIPANTS: A task force of more than 40 experts in disciplines related to the use of neuromuscular blocking agents in the intensive care unit was convened from the membership of the American College of Critical Care Medicine (ACCM) and the Society of Critical Care Medicine (SCCM). EVIDENCE: The task force members provided the personal experience and determined the published literature (MEDLINE articles, textbooks, pharmacopeias, etc.) from which consensus would be sought. Published literature was reviewed and classified into one of four predetermined categories, according to study design and scientific value. CONSENSUS PROCESS: The task force met several times as a whole, and numerous times in smaller groups by teleconference, over a 1-yr period to identify the pertinent literature and arrive at consensus recommendations for the whole task force to discuss. Consideration was given to the relationship between the weight of scientific information and the experts' viewpoints. Over the next year, draft documents were composed by a task force steering committee and debated by the task force members until consensus was reached by nominal group process. The task force draft was then reviewed, assessed, and edited by the Board of Regents of the ACCM. After steering committee approval, the draft document was reviewed and approved by the SCCM Council. DATA SYNTHESIS: To facilitate rapid communication of the three recommendations contained within the complete and unabridged practice parameter document, an executive summary was prepared for publication by the ACCM Board of Regents, and this executive summary was approved by the task force steering committee and the SCCM Executive Council. CONCLUSIONS: A consensus of experts provided three recommendations with supporting data for achieving sustained neuromuscular blockade in critically ill patients: a) pancuronium is the preferred neuromuscular blocking agent for most critically ill patients; b) vecuronium is the preferred neuromuscular blocking agent for those patients with cardiac disease or hemodynamic instability in whom tachycardia may be deleterious; c) patients receiving neuromuscular blocking agents should be appropriately assessed for the degree of blockade that is being sustained. This executive summary selectively presents supporting information and is not intended as a substitute for the complete document.

Adult↗
PubMed1995

Clinical and economic performance criteria for intraarterial and extraarterial blood gas monitors, with comparison with in vitro testing.

The frequency with which blood gas measurements should be obtained is controversial because laboratory-based blood gas analyzers impose blood loss, delay, and cost on each measurement. Point-of-care analyzers eliminate the delay factor, but blood loss and cost factors remain. Optode microsensing can be adopted readily to in vivo monitoring devices that can provide continuous or on-demand blood gas values that do not result in blood loss or added cost to each measurement. This article critically reviews the advantages and limitations of optode-based blood gas monitors based on published data. In addition, a basis for considering the economic effects of extralaboratory blood gas measurement devices (point-of-care analyzers and optode-based monitors) is presented.

Arteries↗
PubMed1995

Intra-arterial and extra-arterial pH, PCO2 and PO2 monitors.

In vitro blood gas analysers inherently limit the frequency of serial blood gas measurements because of blood loss and cost. In vivo blood gas monitors eliminate an inherent cost and blood loss associated with measurement. Optode microsensing is a technology that can be readily adapted to in vivo measurement of pH, PCO2, and PO2. Optode-based intra-arterial devices that display continuous values have been developed that are practical for routine use but consistent performance remains a problem; an extra-arterial device that provides intermittent values has been shown to be consistent but is not yet available for routine use. The transfer of blood gas measurements from laboratory analysers to the combination of point-of-care analysers and monitors should have as profound an impact on acute respiratory care as did the introduction of laboratory-based blood gas analysers over 30 years ago. However, we must be sure these devices are reliable, consistent and cost beneficial in order to avoid widespread adoption of yet another technology that provides more data, more cost, and questionable patient benefit.

Blood Gas Analysis↗
PubMed1995

The history of pH and blood gas analysis.

It is difficult for today's clinician to appreciate the rapid evolution of technology relevant to pH and blood gas measurements. Discovery of the scientific foundations took three centuries, whereas development of practical methods for clinical application took only three decades from the realization of their potential clinical importance. All indications are that advancement will continue at the same pace for the next several decades.

Blood Chemical Analysis↗
PubMed1995

Temperature correction of blood gas values.

The popularity of routine temperature correcting of pH, PCO2 and PO2 values is based on the observation that large differences in the blood gas values are present when the patient's temperature is profoundly hypo- or hyperthermic. This observation leads some clinicians to the unsubstantiated conclusion that uncorrected 37 degrees C values are "wrong." The danger in this superficial thought process is that one might reach the unfounded conclusion that temperature-corrected values are "right." The simple truth is: With significant changes in patient temperature, we do not fully understand the complexity of the effects on metabolism, vascular function, and respiration. Both corrected and uncorrected blood gas values, therefore, are of uncertain usefulness in patients with significant deviations in body temperature. There is no logical or scientific basis for the assumption that temperature-corrected values are better than the values obtained at 37 degrees C. In fact, the available technical and biological data lead to the conclusion that, in almost all circumstances, there is no clinical advantage to using values other than those at 37 degrees C. In addition, the routine process of temperature correction of blood gases involves several practical disadvantages. First, interpretation of the corrected values demands deviation from the familiar and well-documented guidelines for interpreting 37 degrees C values. Second, temperature correction assumes the laboratory has received the patient's true temperature at the time of sampling. My experience is that the patient's true temperature often is not reported or is reported erroneously. Third, temperature-corrected values can be confused with uncorrected values and vice versa. Available data support the practice that only uncorrected (37 degrees C) blood gas values should be used and reported routinely. Temperature-corrected values should be calculated only when specifically requested and the onus for clinical use of temperature-corrected values lies with the clinician who requests them.

Acid-Base Equilibrium↗
PubMed1995

Capnography.

Capnography measures exhaled carbon dioxide and is most useful when applied directly to patient care. This is in circumstances of detecting misplacement of the tracheal tube, dysfunction of respiratory apparatuses, detection of abnormal lung function, successful cardiopulmonary resuscitation, and trending of deadspace changes. The least reliable application is to reflect alveolar ventilation (PaCO2). This application is most common during general anesthesia and weaning from mechanical ventilation. Provided the patient has a stable cardiac status, stable body temperature, absence of lung disease, and normal capnogram, PETCO2 monitoring may assist in estimating PaCO2. The use of capnography in patients with severe respiratory failure should be applied with careful reflection. The increased V/Q mismatch that is consistent with a widened P(a-ET) gradient, as well as worsening hypercapnea with increased peripheral carbon dioxide production, can lead to erroneous PETCO2 values. Capnography may be least useful in the sickest patients.

Capnography↗
PubMed1995

Blood gas monitors.

In vitro blood gas analysis requires limitation of the frequency of serial blood gas measurements for two major reasons--blood loss and cost. In vivo or ex vivo blood gas monitors eliminate these factors because the measurements are available continuously, or as frequently as deemed desirable, without permanently removing blood or imparting additional cost. For patients with arterial catheters in place, the propriety of blood gas monitors is obvious as long as there is no requirement to alter the size, location, or placement of the arterial catheter and the routine use of the arterial catheter system is unaffected. Further, personnel exposure to the patient's blood, and the risk of nosocomial infection from contaminated arterial catheters, should be reduced because the integrity of the arterial catheter and tubing system is not interrupted to obtain blood gas values. Blood gas monitors and point-of-care analyzers should significantly reduce therapeutic decision time (the interval from ordering the test to initiating a therapeutic action based on the test results), thereby enabling rapid titration of common therapeutic modalities such as oxygen administration, positive pressure ventilation, positive end-expiratory pressure, and manipulation of acid-base balance. The transfer of blood gas measurements from laboratory analyzers to the combination of blood gas monitors and point-of-care analyzers should have as profound an impact on acute care medicine as did the introduction of laboratory-based blood gas analysis over 30 years ago. In the current medico-economic environment, however, we must be certain that these devices are reliable, consistent, and cost beneficial in order to avoid widespread application of yet another technology that provides more data, greater costs, and only questionable patient benefits.

Blood Gas Analysis↗
PubMed1994

Discovering active motifs in sets of related protein sequences and using them for classification.

We describe a method for discovering active motifs in a set of related protein sequences. The method is an automatic two step process: (1) find candidate motifs in a small sample of the sequences; (2) test whether these motifs are approximately present in all the sequences. To reduce the running time, we develop two optimization heuristics based on statistical estimation and pattern matching techniques. Experimental results obtained by running these algorithms on generated data and functionally related proteins demonstrate the good performance of the presented method compared with visual method of O'Farrell and Leopold. By combining the discovered motifs with an existing fingerprint technique, we develop a protein classifier. When we apply the classifier to the 698 groups of related proteins in the PROSITE catalog, it gives information that is complementary to the BLOCKS protein classifier of Henikoff and Henikoff. Thus, using our classifier in conjunction with theirs, one can obtain high confidence classifications (if BLOCKS and our classifier agree) or suggest a new hypothesis (if the two disagree).

Algorithms↗
PubMed1994

Hyponatremia in acute spinal cord injury.

OBJECTIVE: To define the occurrence rate, time course, and potential etiologic factors of hyponatremia in patients with acute spinal cord injury. DESIGN: Analysis of data obtained from a retrospective review of medical records and from a systematized, prospective database pertaining to patients with spinal cord injury. SETTING: A university hospital with a federally funded regional spinal cord injury center and a dedicated spinal cord injury intensive care unit. PATIENTS: Two hundred eighty-two patients admitted between January 1, 1988 and December 31, 1989 with acute (< 24-hr duration) spinal cord or vertebral column injury. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The mean age of patients was 36.7 +/- 17.6 (SD) yrs; 225 (80%) of the patients were male and 57 (20%) were female. Hyponatremia, when it occurred, developed at a mean time of 6.4 +/- 6.7 days postadmission, reached its nadir at 8.7 +/- 8.8 days, and occurred in 28% of those patients with cervical injuries, 34% with thoracic injuries, and 27% with lumbar injuries (p = NS). Logistic regression analysis demonstrated that the type of spinal cord injury (Frankel class: range is A = complete neurologic lesion to E = no neurologic lesion) was the strongest predictor of hyponatremia. The occurrence rate of hyponatremia was as follows: Frankel class-A 62%; Frankel class-B 48%; Frankel class-C 41%; Frankel class-D 23%; Frankel class-E 16% (p < .0001). CONCLUSIONS: The prevalence of hyponatremia in acute spinal cord injury is much higher than in the general medical or surgical patient population. This abnormality usually occurs within the first week postinjury. The most significant predictor of hyponatremia is the type rather than the level of spinal cord injury. The potential etiological factors are many and these factors are probably interrelated. The pathophysiological mechanisms that result in hyponatremia must be explored so that this occurrence and its consequences can be prevented.

Acute Disease↗
PubMed1994

A historical perspective on ventilator management.

Paralysis via neuromuscular blockade in ICU patients requires mechanical ventilation. This review historically addresses the technological advances and scientific information upon which ventilatory management concepts are based, with special emphasis on the influence such concepts have had on the use of neuromuscular blocking agents. Specific reference is made to the scientific information and technological advances leading to the newer concepts of ventilatory management. Information from > 100 major studies in the peer-reviewed medical literature, along with the author's 25 yrs of clinical experience and academic involvement in acute respiratory care is presented. Nomenclature related to ventilatory management is specifically defined and consistently utilized to present and interpret the data. Pre-1970 ventilatory management is traced from the clinically unacceptable pressure-limited devices to the reliable performance of volume-limited ventilators. The scientific data and rationale that led to the concept of relatively large tidal volume delivery are reviewed in the light of today's concerns regarding alveolar overdistention, control-mode dyssynchrony, and auto-positive end-expiratory pressure. Also presented are the post-1970 scientific rationales for continuous positive airway pressure/positive end-expiratory pressure therapy, avoidance of alveolar hyperxia, and partial ventilatory support techniques (intermittent mandatory ventilation/synchronized intermittent mandatory ventilation). The development of pressure-support devices is discussed and the capability of pressure-control techniques is presented. The rationale for more recent concepts of total ventilatory support to avoid ventilator-induced lung injury is presented. The traditional techniques utilizing volume-preset ventilators with relatively large tidal volumes remain valid and desirable for the vast majority of patients requiring mechanical ventilation. Neuromuscular blockade is best avoided in these patients. However, adequate analgesia, amnesia, and sedation are required. For patients with severe lung disease, alveolar overdistention and hyperoxia should be avoided and may be best accomplished by total ventilatory support techniques, such as pressure control. Total ventilatory support requires neuromuscular blockade and may not provide eucapnic ventilation.

History, 20th Century↗