Robert Gilbert

Digitalis Intoxication Following Conversion to Sinus Rhythm

The records of 28 patients receiving digitalis and converted from atrial fibrillation or flutter to sinus rhythm with direct-current countershock were reviewed. Electrocardiographic signs suggesting digitalis intoxication following conversion occurred in 20 of these cases. Two of these patients died as a result of ventricular fibrillation several hours after apparently successful conversion. Six patients on digitalis treated with countershock but not converting and five patients converted withcountershock who were not receiving digitalis or in whom digitalis had been discontinued for several days failed to show these electrocardiographic abnormalities. The results indicate that digitalis intoxication will often appear following conversion to sinus rhythm when no indication of digitalis intoxication was present prior to conversion. It is recommended that digitalis be withheld for several days in subjects for whom a conversion attempt is planned.

Functional results of muscle flap closure for sternal infection

The morbidity and mortality of infection after median sternotomy have been substantially reduced with the advent of treatment by wide sternal resection and muscle flap closure. A study was performed comparing the cardiorespiratory function of 13 such patients before and after operation as well as with a control group of 15 patients who underwent similar procedures without complication. The groups were comparable in preoperative pulmonary function, though more patients in the study group had evidence of chronic lung disease. Patients were studied 2 to 39 months after the original procedure. Late postoperative pulmonary function test results, exercise tolerance, and oxygen uptake were not significantly different between the groups, and pulmonary function test results were unchanged in those patients who were tested preoperatively. We conclude that muscle flap reconstruction for sternal infection can be expected to give good long-term functional results. Exercise tolerance and pulmonary function may not differ from a control group of cardiac surgical patients, despite the altered composition of the chest wall. Patients with chronic lung disease may be more prone to have this complication.

Effect on Circulation of Conversion of Atrial Fibrillation to Sinus Rhythm

Treadmill exercise tests were performed in cardiac subjects before and after conversion from atrial fibrillation to sinus rhythm. The most striking changes following conversion were a marked reduction in exercise heart rate and increase in stroke volume and cardiac output. Exercise performance as judged by a standardized exercise test improved significantly in some but not all subjects following conversion. Duplicate control studies in nonconverting subjects failed in general to show these improvements. The results indicate that conversion from atrial fibrillation to sinus rhythm is worthwhile from a functional standpoint in patients with valvular heart disease, and is especially indicated after successful mitral commissurotomy.

The cardiorespiratory syndrome related to obesity: Clinical manifestations and pathologic physiology

Summary The cardiorespiratory syndrome of obesity has been reviewed from the standpoint of its clinical features and pathogenesis. It is felt by the present authors to represent a summation effect of increased need for gas exchange in all cases, increased resistance to ventilation imposed by masses of fat in some cases and inadequacy of the respiratory control system. Such a multiple-factor theory best explains its infrequency and relates it to other situations in which alveolar hypoventilation may develop in the absence of bronchopulmonary disease or kyphoscoliosis. Weight reduction is successful in reversing the syndrome in its earlier phases, but the disease may terminate fatally.

Regional metabolic changes in the myocardium following coronary artery ligation in dogs

Abstract Metabolic and hemodynamic changes were studied in dogs before and at 5 minute intervals following ligation of the anterior descending coronary artery. By placing catheters in the arterial (A), main coronary sinus (CS), and great cardiac vein (CV) positions, it was possible to collect simultaneous samples from the three sites and analyze the effluent for pH, Po 2 , potassium, glucose, pyruvate, and lactate. Following coronary ligation, there was a significant decrease in pH and glucose and an increase in lactate and potassium in the CV samples. The Po 2 value did not change significantly. The CS drainage exhibited minor changes and only when the changes in the CV samples were marked. The hemodynamic changes included a slight fall in blood pressure, an increase in isovolumetric contraction period, and an increase in left ventricular end-diastolic pressure following coronary ligation. The results and the technique are discussed with emphasis on metabolic alterations in regional venous drainage following coronary artery ligation.

Reactive airways dysfunction syndrome presenting as a reversible restrictive defect

A 25-year-old farm worker developed acute bronchopneumonia after heavy exposure to a respiratory irritant in a silo. He recovered from the acute episode but then experienced chronic dyspnea and fatigue. Pulmonary function testing showed small lung volumes with a normal ratio of 1 s forced expiratory volume/forced vital capacity (restrictive defect). This defect improved markedly with bronchodilator treatment and changed to a mixed obstructive/restrictive defect with methacholine challenge. We believe that this is an example of the reactive airways dysfunction syndrome manifested by a restrictive rather than obstructive defect. Constriction of airways at the bronchoile or alveolar duct level is the most likely cause of the syndrome.

The Pulmonary Diffusing Capacity in Congenital and Rheumatic Heart Disease

The pulmonary diffusing capacity was determined both in patients with intracardiac septal defects and in patients with valvular heart disease in an effort to find out whether pulmonary congestion and hyperemia as they occur ill cardiac disease have different effects on the process of gas diffusion and whether these effects vary at different stages of the disease process.

Breathing pattern during CO2 inhalation obtained from motion of the chest and abdomen

A method is described for obtaining tidal volume from movements of the chest and abdomen utilizing electromagnetic sensors. Tidal volume obtained from these sensors was linearly related to tidal volume simultaneously obtained with a spirometer within an error of 14 per cent. With this method, the ventilation-tidal volume relationship was studied during CO2 inhalation. This relationship was curvilinear and closely approximated a parabola: Vt = a Ve + b VE2, where Vt = tidal volume and Ve = minute ventilation. The numerical value of b was always negative so that at high ventilations the tidal volume tended to level off and increases in ventilation occurred primarily as a result of increases in frequency. The value of tidal volume and the ratio of tidal volume to vital capacity at which leveling off of the tidal volume occurred was variable among individuals and often differed in the same individual on different occasions. Added resistive and elastic loads altered the Ve — Vt curves in the direction of minimal respiratory force or minimal respiratory work. The use of a mouthpiece, directional valve and noseclip did not alter the Ve — Vt relationship. There was no sex difference in the proportions of the total tidal volume contributed by chest and abdomen motion and these proportions did not change significantly with increasing ventilation in the majority of subjects.

Measurement of maximum inspiratory pressure during routine spirometry

Maximum inspiratory airway pressure (PI max) was measured as part of routine spirometry in a series of 236 subjects. With men and women considered separately, PI max was tested for correlation with age and height, FEV1, FIV1 and vital capacity. The best linear correlation was with FIV1. Prediction formulas for the lower limit are as follows. For men: PI max (cm H2O) = −10 + .021 FIV1 (ml). For women: PI max = − 6 + .019 FIV1. Appropriate formulas are also presented using FEV1 and vital capacity. Values for PI max below these predicted values can be considered reduced out of proportion to the ventilatory defect with approximately 95% confidence. Measurement of PI max may add useful information to the spirogram, but low values are not specific and must be interpreted in the clinical context.

Pulmonary effects of heart failure.

In the normal lung, gas and fluid exchange takes place simultaneously. Although gas exchange is the major function of the lung, fluid exchange is the function primarily disturbed by pulmonary edema. Knowledge of normal fluid transfer is necessary for an understanding of the clinical and laboratory manifestations of pulmonary edema.