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Biomedical subjects

J J Osborn

Publications and source records attributed to J J Osborn.

At least 19 recordsLinked to original sources
PubMed1977

Turbulent airflow meter for long-term monitoring in patient-ventilator circuits.

A new type of flowmeter is described which operates on the principle that pressure drop (deltaP) produced by turbulent volume flow (V) through a simple resistance chamber obeys a relation of V = K (deltaP)0.50. Data are given showing that the device follows a true power law with a single exponent for airflows ranging from 3.5 to 270 l/min. Standard instrumentation and a linearization circuit are used with the new flowmeter to provide linear steady-state and alternating airflow measurements up to peak rates of 150 l/min and frequency to 15 Hz. Data are presented comparing integrated airflow readings from the new turbulent flowmeter and a laminar-type flowmeter. The turbulent airflow meter appears to offer increased reliability for long-term patient monitoring use in patient-ventilator circuits.

Pulmonary Ventilation↗
PubMed1977

Reduction of unexpected, life-threatening events in postoperative cardiac surgical patients; the role of computerized surveillance.

With increasing use of computerized surveillance (CS) in critical care, a key question is whether it favorably influences clinical outcome. Knowing that two intensive care unit beds would soon have CS capability, we embarked on an uninterrupted prospective study in which the incidence of sudden, unexpected life-threatening events (SULTE) was compared in post-open heart surgery patients whose subsystem performances were evaluated by conventional methods (CM) as opposed to those who would be followed by CS involving automatic acquisition and generation of 30 cardio-respiratory variables. We evaluated 211 patients, 91 with CM and 120 by CS. Since CS availability was limited, sicker patients were given priority for the two CS beds. Despite the obvious bias in favor of CM, there was a statistically significant reduction (P less than 0.001) in the incidence of SULTE in those patients followed by CS (1 of 120 patients: 0.8%; no SULTE-related deaths) in comparison to the CM patients (11 of 91 patients: 12%; two SULTE-related deaths.) The data suggest that computerized surveillance can play a role in reducing morbidity and possibly mortality in postoperative cardiac surgical patients.

Adult↗
PubMed1976

An analysis of potential physiological predictors of respiratory adequacy following cardiac surgery.

More than 50 potential physiological and clinical predictors of postoperative respiratory adequacy were examined in an attempt to identify those few variables which, singly or in combination, best predicted the outcome of the first trial of spontaneous respiration following cardiac surgery. This trial was initiated when patients seemed hemodynamically stable and relatively alert following surgery. Analysis of data from 124 patients identified the following useful predictors: forced vital capacity, total lung capacity, and maximal mid-expiratory flow rate from preoperative pulmonary function tests; resting cardiac index from preoperative cardiac catheterization; postoperative compliance and resistance measured by a computer-based monitoring system; postoperative vital capacity per kilogram, and maximum inspiratory force, measured at the bedside prior to the weaning trial. Stepwise linear discriminant analysis indicated that vital capacity per kilogram and maximum inspiratory force were the most useful predictors, the dividing line between successes and failures being represented by a vital capacity per kilogram of 15 ml. and a maximum inspiratory force of 28 cm. H2O. Mean values of successes were 18.3 +/- 7 ml. per kilogram and 30.7 +/- 9 cm. H2O and, for failures, 11.9 +/- 4 ml. per kilogram and 24.3 +/- 8.4 cm H2O. These physiological variables assess patient effort acting upon an abnormal pulmonary system. Measurements of passive pulmonary mechanics, cardiac function, and the measurement of arterial blood gases were suprisingly poor predictors.

Airway Resistance↗
PubMed1975

Recent experience with a respiratory monitoring system in intensive care.

Computer based instrumentation for continuous monitoring of airway flow, pressure, O2 and CO2 concentration offers an improved noninvasive management technique for patients on mechanical ventilators. Computation of these basic signals provides routinely the following measurements: respiratory rate, tidal volume in and out, minute ventilation, positive end-expiratory pressure, mean airway pressure, inspiration-expiration ra measurements, except for O2 consumption and partially for tco2 production. The system works as a monitor of the respirator (detection of malfunction) and as a monitor of the lung function of the patient. It is particularly useful when adjusting the respirator and at time of weaning a patient from the respirator. These maneuvers can be made more safely because they are based on objective measurements and followed by immediate new sets of data. Defining the optimal values of tidal volume and positive end-expiratory pressure has been simplified by the use of pressure-volume plots. A "fighting", is now used as a measure of the severity of "fighting", that is of the effort of the patient to breathe spontaneously while being ventilated. It can detect fighting before it is diagnosed clinically and so can provide a warning that significant physiological changes will occur unless the fighting is controlled. New information about the distribution of ventilation-perfusion ratio can be derived from the expired concentration curve for CO2. Quantitative measurement of the distribution of ventilation shows a very close correlation with clinical events and can be carried out automatically during the normal routine of care of the patient. These on-line quantitative measurements, with the immediate reporting of results, appear to make a positive contribution to patient care.

Belgium↗