Ivan W. Brown

Cardiovascular and blood gas responses to hyperbaric oxygenation

Abstract Ten normal subjects were studied while they breathed air and 100% oxygen at 1 and 3.04 atmospheres. Oxygen inhalation at 3.04 atmospheres was associated with a significant increase in arterial and venous pO 2 and O 2 content. Hemoglobin in the venous circulation was completely saturated in 8 of 10 subjects. Oxygen inhalation at 3.04 atmospheres produced a small but significant increase in venous pCO 2 , presumably due to the loss of the buffering effect of reduced hemoglobin. Heart rate and cardiac output fell significantly with little change in stroke volume during oxygen inhalation at 3.04 atmospheres, indicating that the decrease in cardiac output was rate-dependent. There was little change in mean arterial pressure but an increase in calculated peripheral resistance during oxygen inhalation at 3.04 atmospheres. Two subjects who demonstrated signs of acute oxygen intoxication did not differ significantly from the group as a whole either in terms of blood gas values or patterns of hemodynamic response.

HEMATOLOGIC PROBLEMS ASSOCIATED WITH THE USE OF EXTRACORPOREAL CIRCULATION FOR CARDIOVASCULAR SURGERY

Excerpt Extracorporeal circulation maintained by an artificial heart-lung apparatus is now an essential and established procedure for certain types of cardiovascular surgery. With this new developm...

Hyperbaric Oxygenation: The Eye as a Limiting Factor

In dogs exposed to 100 percent oxygen at 3 atmospheres absolute pressure for more than 4 hours, a characteristic retinal lesion, manifested as the cytoid-body change, occurs. The selectivity of this injury suggests that the eye may be used as a sensitive indicator and as a site for study of oxygen toxicity. The cytoid body, an entity of disputed genesis, was produced experimentally for the first time.

Infundibular pulmonic stenosis due to a pericardial band

Abstract The symptoms, signs and hemodynamic and operative findings in a patient with a pericardial band which produced an unusual type of infundibular pulmonic stenosis are reviewed. This lesion has been reported in 2 other patients on whom previous cardiac surgery had been performed. However, this patients findings are unique in that the pericardial band developed without a definite history of previous pericarditis or pericardial surgery.

The effect of inflation of the stomach upon the gastroscopic picture

1. Inflation of the stomach effects marked alterations in the gastroscopic picture. 2. Hypertrophic folds can be effaced by inflation. 3. In the dog, the typical picture of “atrophic gastritis” can be produced at will by inflation. 4. In some instances in man, apparently normal folds will disappear under pressure and blood vessels will be seen. 5. The diagnosis of chronic gastritis by means of the gastroscopic picture should be the subject of further critical studies.

The occurrence of gastritis as diagnosed by gastroscopy in gastric neuroses

1. Chronic gastritis, as diagnosed by gastroscopy, is not common in North Carolina. 2. The symptoms of most patients usually classified as having gastric neuroses cannot be explained on the basis of a chronic gastritis. 3. Hemorrhagic, or pigment spots, are common (25%), but their significance has not been determined.

Unusual observations during pacemaker therapy for complete heart block

Abstract During the course of management of spontaneously occurring complete heart block with Stokes-Adams syndrome in a 10 year old boy, rare clinical, therapeutic and physiologic observations were made. Initially, cardiac rate was controlled via a catheter electrode. The effect of ventricular rate on right atrial pressure was shown. There was a progressive fall in right atrial pressure as the ventricular rate was increased from 36 to 100/min. A Chardack pacemaker was implanted permanently, and cardiac rate was controlled with a 9-volt stimulus. During steroid therapy, retrograde atrial conduction and normal sinus rhythm developed. Unusual cardiac arrhythmias allowed electrocardiographic data to be obtained concerning the “vulnerable period” of the cardiac cycle in man. During alternating periods of normal sinus rhythm and pacemaker-controlled rate, ventricular premature beats resulted only when stimuli fell in a period of less than 30 msec, preceding the apex and during the descending portion of the T wave. Additionally, it was shown that stimuli in the “vulnerable period” of the cardiac cycle resulted in premature beats with QRS complexes of “multiform” shape. Although a single stimulus (considerably above the premature beat threshold value) placed in the vulnerable period can initiate ventricular fibrillation, a 9-volt stimulus was insufficient to reach ventricular fibrillation threshold in our patient. Steroid therapy was discontinued with subsequent loss of atrioventricular conduction. Pacemaker failure (due to breakage of a resistor wire) occurred 12 months postoperatively. Successful substitution of the abdominal wall pacemaker was made. At the time of pacemaker substitution, the threshold voltage required to control ventricular rate was 4.6 volts indicating that there had been no significant increase in myocardial resistance after one year.

The Relation between Storage Time of Erythrocytes and Their Percentage Viability after Transfusion

During storage of blood the percentage of viable erythrocytes decreases at such a rate that when these percentages are plotted against time of storage, they fall on an S‐shaped curve. This curve can be explained on the assumption that the resistance of red cells to in vitro aging is normally distributed, i.e., follows the normal probability curve. By a mathematical transformation used in other cases of biological standardization, the curve can be changed to a straight line, the slope of which, if accurately determined with a sufficient number of recipients, is the most accurate method of estimating the rate of in vitro aging.

The significance of hemorrhagic or pigment spots as observed by gastroscopy

1. Hemorrhagic or pigment spots in the gastric mucosa can be produced by aspiration of the stomach. 2. They may occur in healthy individuals. 3. Their relationship to peptic ulcer is questionable. 4. They probably have no clinical significance. 5. The factor of trauma should be carefully considered in the interpretation of gastroscopic findings.

Cholinesterase activity and potassium permeability in human erythrocytes.

Summary Inhibition of human erythrocyte cholinesterase with or without exogenous AcCh had no effect on loss of potassium from cells during storage at 4°C or during incubation at 37.5°C. The re-entry at 37.5°G of potassium into cells previously stored for 24 hours at 4°C to permit its leakage into the serum was also unaffected.