Journal of clinical monitoring and computing
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J Clin Monit Comput · May 1998
Transcutaneous renal function monitor: precision during unsteady hemodynamics.
Hospital acquired renal dysfunction, most commonly caused by renal hypoperfusion, dramatically increases mortality in intensive care patients. Glomerular filtration rate (GFR) is rapidly altered during renal hypoperfusion, and a more rapid means of GFR measurement may prompt institution of renal-specific therapy. We hypothesized that a transcutaneous renal function monitor can rapidly and accurately assess acute changes in GFR within a time frame much shorter than the 2-4 hours currently available. ⋯ TC monitoring provides prompt indication of directional changes in GFR and may provide the clinician warning of inadequate resuscitation. Prospective analysis of the specificity, sensitivity, and TC guided renal-specific resuscitation is needed.
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J Clin Monit Comput · May 1998
Use of a neonatal blood pressure cuff to monitor blood pressure in the adult finger--comparison with a standard adult arm cuff.
There are few suitable methods for monitoring blood pressure continuously (or intermittently) for research in adult stroke patients, who are ill but do not justify invasive intensive care monitoring. ⋯ The reproducibility of sequential blood pressure measurements made with the finger cuff was better than with the arm cuff. The performance of the finger cuff compared with that of the arm cuff was sufficiently good to encourage use of the finger cuff in research involving automatic intermittent monitoring to observe sequential blood pressures over time in stroke patients. However, measurements of systolic and diastolic pressure were not the same with the two cuffs and further work on calibration of the finger cuff would be useful.
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J Clin Monit Comput · May 1998
Adaptive lung ventilation (ALV) during anesthesia for pulmonary surgery: automatic response to transitions to and from one-lung ventilation.
Adaptive lung ventilation is a novel closed-loop-controlled ventilation system. Based upon instantaneous breath-to-breath analyses, the ALV controller adjusts ventilation patterns automatically to momentary respiratory mechanics. Its goal is to provide a preset alveolar ventilation (V'A) and, at the same time, minimize the work of breathing. Aims of our study were (1) to investigate changes in respiratory mechanics during transition to and from one-lung ventilation (OLV), (2) to describe the automated adaptation of the ventilatory pattern. ⋯ Respiratory mechanics during transition to and from OLV are characterized by marked changes in R and C into opposite directions, leaving TC unaffected. The ALV controller manages these transitions successfully, and maintains V'A reliably without intervention by the anesthesiologist. VT during OLV was found to be consistently lower than recommended in the literature.
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We have previously shown in a mechanical lung model [1] that bronchial flap-valve expiratory obstruction results in sequential lung expiration, best detected by prolonged and low magnitude tracheal expired flow (V) from the obstructed lung. However, the normal expiratory resistance of clinical ventilation circuits might also generate prolonged, low value exhaled V, that could be confused with bronchial flap-valve obstruction. We reasoned that bronchial flap-valve obstruction would also cause sequential CO2 unloading from each lung and result in a biphasic tracheal capnogram. ⋯ During moderate or severe left bronchial flap-valve obstruction, left bronchial V was delayed so that the left lung anatomical dead space (devoid of CO2) mixed with normal right exhalate to depress the expiratory upstroke or early plateau of the tracheal capnogram. During severe obstruction, decreased perfusion of the left lung caused lower alveolar PCO2. Then, prolonged low V from the left bronchus also resulted in depression of the end of the tracheal alveolar plateau. In general, the low magnitude of bronchial V from the obstructed lung limited its effect on the tracheal capnogram and the best marker of sequential lung emptying during bronchial flap-valve obstruction may be late exhaled V without reduction in total tidal volume.
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J Clin Monit Comput · May 1998
Functional residual capacity measurement during tracheal gas insufflation.
Tracheal gas insufflation (TGI) is considered an adjunctive method to enhance carbon dioxide elimination during permissive hypercapnia in patients with acute respiratory distress syndrome. Due to increasing tidal volume and/or expiratory resistance, TGI may cause intrinsic PEEP (PEEPi), and may lessen the advantages of permissive hypercapnia. There is no reliable method to measure PEEPi during TGI. Using an argon washout method to evaluate dynamic hyperinflation, we developed a method to measure FRC with TGI flow. ⋯ The system developed in this study can be used as a method to detect air-trapping during TGI.