J. Howland Auchincloss

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.

Pulmonary Function Following Mantle-Field Irradiation for Hodgkin's Disease

Following mantle-field irradiation for Hodgkins disease, patients experience a transient acute pulmonary reaction resulting in a decreased vital capacity and forced expiratory volume. This reaction begins 2-3 months after the start of therapy, reaching a maximum intensity at 4-6 months and subsiding by about 8 months. In patients with intrathoracic disease, the improvement following tumor regression may result in a net increase in pulmonary function following treatment.

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.

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.

Preoperative Evaluation of Pulmonary Function

After an overview of preoperative evaluation of pulmonary function, an approach based on spirometry and arterial blood gas analysis is outlined, similar to that used in many hospitals. A discussion follows of additional tests which, although infrequently used, may aid the evaluation of risk before pneumonectomy.

Significance of relative rib cage and abdomen motion in patients with chronic obstructive pulmonary disease

Changes in intrapleural pressure (ΔPpl) and abdomen pressure (ΔPab) were related to changes in the anterior-posterior diameter of the rib cage (ΔRC) and abdomen (ΔAb) in 17 patients with chronic obstructive pulmonary disease (COPD).ΔPab-ΔPpl equalsΔPdi, the change in transdiaphragmatic pressure. Measurements were made during quiet inspiration in the semierect position.ΔAb/(ΔAb+ΔRC) was used as a measure of relative abdomen motion, andΔPab/ΔPdi was used as a measure of the relative contribution of descent of the diaphragm to the breathing process. Patients with COPD developed greater ΔPdi than normal subjects. This increasedΔPdi was the result of relatively more intercostal and accessory muscle activity rather than increased diaphragm motion. Despite this, patients with COPD showed the same relative abdomen motion as did normal subjects. Observation of relative chest and abdomen motion in patients with COPD is a poor guide to relative use of the rib cage muscles and diaphragm.

A new ventilator designed to meet the present-day needs of mechanical aid to ventilation in the treatment of respiratory failure

SummaryA description is presented of an internal ventilator which has the following features: (1) patient-triggering with guaranteed minimum frequency; (2) constant volume or constant ventilation as determined by the physician; (3) continuous, automatic monitoring of expired air tidal volume; (4) optional negative phase when ventilation is maintained at constant levels; (5) control over inspiratory flow rate and air-oxygen ratios. The ventilator has been tested under laboratory conditions and in separate series of short-term and long-term applications, and has been found useful because it provides the responsiveness and flexibility of patient-triggered apparatus, the basic security of constant ventilation or guaranteed minimum ventilation, and an automated system for monitoring ventilation. The rationale for design of a ventilator with these refinements is discussed and relates to the present population of patients requiring mechanical aid to ventilation.RésuméOn présente la description d’un ventilateur interne qui a les caractéristiques suivantes: (1)déclenchement par le malade avec un minimum garanti de fréquence;(2)un volume constant ou une ventilation constante tel que prescrit par le médecin;(3)un contrôle continuel, automatique du volume d’air courant expiré;(4)une phase négative facultative quand la ventilation est maintenue à des niveaux constants;(5)un contrôle sur le flot inspiratoire et sur les rapports air/oxygène. Le ventilateur a été éprouvé en laboratoire et en séries d’application séparées à long et à court terme, et il a été trouvé utile parce qu’il a la sensibilité et la flexibilité d’un appareil déclenché par le malade; il garantit la sécurité primordiale d’une ventilation constante ou d’une ventilation minimale, et il est muni; d’un système automatique pour contrôler la ventilation. La raison d’être d’un appareil possédant tous ces raffinements est démontrée, et l’on rappelle le nombre de malades qui peuvent bénéficier d’une aide mécanique à la ventilation.