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Biomedical subjects

R L Johnson

Publications and source records attributed to R L Johnson.

At least 361 records · Page 20Linked to original sources
PubMed1979

Reflex cardiovascular depression during unilateral lung hyperinflation in the dog.

We have examined whether lung hyperinflation in the anesthetized dog reflexly depresses cardiac output, stroke volume, heart rate, and blood pressure and whether these changes persist for more than a minute. To eliminate any mechanical restriction to venous return and pulmonary blood flow during lung hyperinflation, a model was developed in which all pulmonary artery blood flow and all ventilation were directed to the right lung in dogs with widely open chest and the left lung was hyperinflated before and after left cervical vagotomy. Heart rate, stroke volume, and blood pressure decreased by 24, 20, and 27%, respectively, within 15 s of left lung inflation to 30 cm H(2)O. Heart rate increased to preinflation levels by 1 min, but stroke volume and blood pressure remained depressed during lung hyperinflation for at least 15 min. Upon deflation, stroke volume and blood pressure returned to control levels within 1 min. Division of the left vagosympathetic trunk at the neck interrupted all autonomic afferent and efferent nerves of the left lung, but left intact the right vagal sympathetic and parasympathetic afferent and efferent nerves of the heart. After left cervical vagotomy the transient fall in heart rate, stroke volume, and blood pressure during left lung hyperinflation was greatly reduced or eliminated. These results suggest that unilateral lung hyperinflation reflexly depresses heart rate and blood pressure, which are partially compensated with time, and reflexly depresses stroke volume, which persists uncompensated until the lung is deflated. These findings may explain the depressed cardiovascular function observed during regional lung overdistention especially when it occurs during positive pressure ventilation.

Anesthesia↗
PubMed1979

The legal perspective. How much process is due?

The essentials of a fair due process proceeding are a written statement of the charges; timely notice of hearing; a fair hearing before a deciding board; a right to produce evidence; a decision based on "substantial evidence" produced at the hearing; and a right to counsel under certain circumstances. Although a physician is entitled to a hearing in the event of denial of staff appointment or the total revocation or suspension of privileges, the hospital should have the prerogative to monitor a physicians's performance without triggering all of the due process safeguards.

Hawaii↗
PubMed1979

Hospital buildings have few alternative uses.

A year ago HEW published guidelines regulating hospital beds and occupancy rates. Reluctant to close their doors, administrators have sought conversion alternatives, most of them impractical and economically impossible. A go-slow attitude is recommended, as population increases will dictate hospitals' proper response.

Bed Occupancy↗
PubMed1979

Colitis cystica profunda.

Colitis cystica profunda, although rare in occurrence, deserves recognition as a distinct pathologic entity. Several types of clinical presentation have been recognized, the most common being a solitary lesion in the rectum. The cause is generally ascribed to the reparative process associated with chronic mucosal inflammation. Differentiation of this entity from mucus-producing adenocarcinoma should be possible with an adequate biopsy. Conservative excision is appropriate therapy, depending on the clinical manifestations.

Adenocarcinoma↗
PubMed1978

Controlled oxygen administration in acute respiratory failure in chronic obstructive pulmonary disease: a reappraisal.

Controlled oxygen therapy may aggravate carbon dioxide retention during acute exacerbations of chronic obstructive pulmonary disease (COPD). Of 50 consecutive patients with COPD and acute respiratory failure, 13 required intubation because of carbon dioxide narcosis. With discriminant analysis of their arterial oxygen tension (PaO2) and pH on admission, a diagram separated patients into those at high risk and those at low risk for carbon dioxide narcosis. This diagram was then used to predict carbon dioxide narcosis in 73 patients with COPD and acute respiratory failure who were treated with controlled oxygen. In 16 of these patients carbon dioxide narcosis developed. Thirteen (81 per cent) were predicted by the diagram to be at high risk for this complication. Only two (4 per cent) patients judged by the diagram to be at low risk for carbon dioxide narcosis required mechanical ventilation. Utilizing an oxygen tension (PO2), carbon dioxide tension (PCO2) diagram a patient's ventilatory response was compared to that of ambulatory patients with COPD. These data suggest that hypoxemia and acidosis are more discriminatory for "carbon dioxide narcosis" than hypercapnia.

Acute Disease↗
PubMed1978

Sawtooth waves: concomitants of rapid eye movement sleep in monkeys.

Sawtooth waves, 2--3 c/sec activity of at least 40 micro V, occurred primarily during clusters of REMs in stump-tailed macaques. On the average the activity began well after the onset of REMs but occasionally occurred soon before or immediately after a cluster of REMs. The activity was clearly defined but occupied less than 0.6% of an 8-h sleep record. A sawtooth burst was, on the average, 7.5 sec in duration.

Animals↗
PubMed1978

Study of the structural requirements for dopa potentiation and oxotremorine antagonism by L-prolyl-L-leucylglycinamide.

A number of analogs of the tripeptide L-prolyly-L-leucylglycinamide (1) were synthesized and evaluated in the Dopa potentiation and oxotremorine antagonism tests. The replacement of the glycinamide residue with either the glycine methylamide, glycine, aminoacetonitrile, amino-2-propanone, semicarbazide, or beta-alaninamide residues resulted in a loss of activity in both tests. A 1:1 mixture of L-prolyl-L-leucyl-(-)-thiazolidine-2-carboxamide (8) and L-prolyl-L-leucyl-(+)-thiazolidine-2-carboxamide (9) showed marked activity in the Dopa potentiation test but was unable to antagonize the tremors induced by oxotremorine. L-Prolyl-L-leucyl-L-prolinamide (11), on the other hand, was active in the oxotremorine antagonism test but inactive in the Dopa potentiation test. The replacement of the pyrrolidine ring of 1 with either a thiazolidine or cyclopentane ring system caused a loss of activity. The cyclopentanecarboxylic acid analogue 13, however, was found to have moderate activity in the serotonin potentiation test.

Aggression↗
PubMed1978

Rapid cryoglobulin screening: an aid to the clinician.

A rapid screening method for serum cryoblobulin is reported. It requires only common laboratory equipment and is based upon the detection of light scattering (500 millimicron) in the early phase of cryoaggregation. All of 28 sera negative for cryoglobulins by the conventional 5-day incubation method were negative by the screening method. Conversely, all sera containing 60 microgram/ml or more of mixed cryoglobulins were positive by the screening method. The initiation phase of cryoprecipitation in mixed cryoglobulins was found to be prompt, as reported previously for monoclonal cryoglobulins. This sensitive method of cryoglobulin detection provides results to the clinician within 2 hours, a helpful insight where consideration of possible immune complex vasculitis exists.

Cryoglobulins↗
PubMed1978

Cardiovascular effects of positive end-expiratory pressure in dogs.

Our purpose was to reexamine the relationship of the fall in cardiac output and blood pressure which occurs during positive end-expiratory pressure (PEEP) to changes in transmural right atrial and left atrial filling pressures. Closed-chest dogs, half with pulmonary edema, were studied during spontaneous breathing and inspiratory positive-pressure breathing (IPPB) with 0-15 cmH2O PEEP. Mean esophageal pressure accurately reflected changes in pericardial pressure and was used to estimate extracardiac pressure. We found that cardiac output fell approximately 50% and blood pressure fell 20% during 15 cmH2OPEEP in spite of well maintained transmural right atrial and left atrial (or pulmonary artery wedge) pressures suggesting a primary or reflex depression of atrial or ventricular function.

Anesthesia↗
PubMed1978

The power broker--prototype of the hospital chief executive?

To some people power brokers manipulate because they lack a solid grounding in management. Power brokering is not an equation of manipulation or management; rather it is the application of solid management techniques combined with a deep understanding of how people behave as human beings.

Behavior↗
PubMed1978

Hospitals in Wonderland.

The hospital industry faces a choice. It can follow a path of involvement with HEW and HMOs, with the prospect of eventually being dominated by them, or it can work toward a position of neutrality, attempting energetically to influence Congress on behalf of the legitimate concerns of both hospitals and government.

Costs and Cost Analysis↗