William A. Spencer

Patterns of sinus arrhythmia in patients with lesions of the central nervous system

Abstract Simultaneous recordings of respirations and instantaneous cardiac frequency by means of a cardiotachometer permit visualization of the sinus arrhythmia due to respiration. Observations made on tracings obtained from 102 patients with a variety of neurologic disorders indicate that the typical respiration-heart rate response may be disturbed by lesions affecting the cardioregulatory mechanisms. Decerebration results in prominent periodic waves of acceleration of the heart rate followed by rebound deceleration. These waves coincide with each deep breath or outburst of periodic breathing. A fixed cardiac frequency is indicative of a complete disconnection between the cardiac pacemaker and the regulatory centers of cardiac activity. Cervical spinal cord transections may cause preponderant bradycardia. It is suggested that simultaneous recordings of the pneumogram and the cardiotachogram may yield useful information regarding the integrity of the regulatory centers of cardiac activity.

Graphic recording of the korotkoff sounds

Abstract The characteristics of the ausculatory method are analyzed in terms of predominant frequencies in the various phases. The data demonstrate the appropriateness of employing graphic methods for inscribing these sounds directly superimposed on a record of occluding cuff pressure. A simple instrument using this principle is described and its usefulness demonstrated in man and laboratory animals.

The total lung capacity and its subdivisions in respiratory poliomyelitis.

Abstract The supine total lung capacity and its subdivisions has been determined in 62 patients with respiratory muscle paralysis due to poliomyelitis. The results were contrasted with those obtained using the same methods in 50 healthy subjects matched according to age, sex, and physical characteristics. A significant reduction of the total lung capacity was found in the patients. This was accounted for by reductions or alterations in the functional residual capacity and the maximum lung volume above the resting expiratory level. The frequent reduction of functional residual capacity was more marked in the patients studied after 2 years from onset of their illness. Respiratory muscle paralysis, duration of illness, thoracic deformities, and prolonged artificial respiration were considered to be contributory to these lung compartition changes.

Circulatory disturbances in life-threatening poliomyelitis☆☆☆

Abstract The frequency of clinically detectable cardiovascular abnormalities in the course of life-threatening poliomyelitis has been presented. The diagnostic criteria and recommended treatments for these conditions have been given. The description of circulatory complications was derived from experience with 1,490 acute poliomyelitis patients in a respirator center. A number of clinical examples of the pattern of disturbed function of nervous regulatory mechanisms, behavior of systemic and pulmonary circulation, and alterations of cardiac activity have been reviewed. Pathophysiologic changes in vital functions due to poliomyelitis complicated by respiratory insufficiency or swallowing difficulty have shown variability of timing and intensity. Experience indicates that careful and constant individualization in the planning and execution of preventive measures and treatment regimens is extremely important. Serial investigation of abnormal function affords guidance and knowledge that is particularly helpful in establishing definitive treatment and prognosis.

The Impact of Electronics on Medicine, Part 1

Realization of the full potential of electronic instrumentation in clinical medicine must await solution of important problems of data interpretation and analysis as related to medical practice. Electronic instrumentation already is highly developed in areas of laboratory measurement and scientific research. Participation by the practicing physician is especially needed to define the areas wherein developmental efforts in the field of electronics may prove most fruitful. Understanding of the advantages and limitations of these devices also is essential in the selection of pertinent measurements and interpretation of the data.

Short Distance Broadcasting of Physiological Data

For the transmission of physiological data not requiring complete freedom for the subject, a direct wire system offers many practical advantages including low cost and high reliability. Such a system is particularly well adapted for bedside monitoring and for the usual studies in the clinical laboratory where the patient is required by his illness to be in a fixed position. For general purpose physiological telemetery, it is necessary to transmit a bandwidth extending to zero cycles per second. Experience has demonstrated that such transmission is possible over a direct wire circuit for a distance of at least half a mile. An over-all response time of 100 ?sec provides an adequate bandwidth for the most rapidly changing physiological events.

Pulmonary nitrogen clearance in the first two years of poliomyelitis with respiratory muscle paralysis

Abstract Lung gas distribution and mixing during artificial respiration were studied in 35 patients with respiratory muscle paralysis caused by poliomyelitis. The onset of their disease had occurred within 2 years before the time of study. The results were contrasted to those obtained during natural breathing in 50 healthy persons of similar ages, sexes, and physical characteristics. In general, but not invariably, the values of clearance equivalent of the patients were lower than those obtained in good health. It is assumed that in these patients some decrease in anatomic dead space and regional changes in the alveoli take place. We postulate from this study that the prevailing pulmonary condition in the early course of artificial respiration and respiratory muscle paralysis is one of a reduced total number of ventilated alveoli that may be larger than normal and have increased “accessibility” to tidal ventilation. These are probably interspersed with small atelectatic areas. This situation may change with time and the extent to which natural breathing can be resumed. The significance of these findings for pulmonary gas exchange and diffusion is unknown.

FACTORS OF SIGNIFICANCE IN THE RESPIRATORY SYSTEM

A description of the normal process of respiration and its comparison to artificial pressure breathing appears to he useful in identifying both the rernarkabIe similarities and some iiiiportant differences between these processes under abnormal circumstances. In the classic mechanical and biochemical sense, normal respiration may be defined as the optimuni adjustment of rate, depth, axid pattern of hreathing that meets the metabolic dernaiid for oxygen uptake and carbon dioxide elimination with ininiinal expenditure of energy by the respiratory muscles. This definition refers to the quiet, steady state and is therefore of less precise meaning in the unsteady states accompanying extremes of physical activity or during the adjustments occasioned by disease, injury, or the administration of pharniacological agents. In the preparation for, and in the conduct of, general anesthesia the central nervous system, neuroniuscular activity, and general cellular metabolism may be affected by the pharmacological agents aclministered. However, since controlled respiration during anesthesia must meet the needs of metabolism for oxygen uptake and carbon dioxide eliniination, this definition has had a primitive durability for the anesthesiologist and physiologist alike. From a functional viewpoint, respiration can be considered as a critically regulated, autorhythmic vital function, operating ceaselessly in the absence of voluntary cortical or suhcortical reflex challenge. Respiratory activation, in its iiorinal ebb and flow, achieves, through its neuroinuscular and pulmonary counterparts, a degree of alveolar ventilation that preserves primarily the ratios of oxygen to carbon dioxide and hydrogen to lkarbonate ion in a homeostatic manner. Respiration possesses a capacity for rapid fluctuations in rate, in amplitude, and in pattern of activity particularly suited to the transitory supremacy of purely nervous functions. In this manner the demands of such voluntary activities as verbal communication and emotion, the protective reflexes of coughing and sneezing, and the acljustments to extremes of physical activity are readily met. The chemical regulation so characteristic of the quiet state, and the rapid oscillations in response to changes in the l,iocliemical substratum of the extracellular and intracellular fluids descrihe h i t a part of the total function. Ihchemical regulation can he considered to sustain the cellular integrity essential for the extensive variations of the respiratory act. Thus the controls that perpetuate the system at one level can be considered preparatory to the range

An improved heart-lung preparation ventilated by negative pressure

Five isolated canine heart-lung preparations were successfully ventilated with intermittent negative pressure in a specially constructed chamber. Improved cardiopulmonary dynamics resulted in increased survival time and improved performance of all preparations. Results obtained with these preparations exceed most of the others reported in the literature. Submitted on May 9, 1960