Cancellation of esophageal electrocardiograms

Southern

970

Society

at the 9.8 per cent NaCl level the respective values were 170 mm. Hg and 184 mm. Hg. Significant survival protection was apparent in the 5.6 and 8.4 per cent NaCl diets. Survival of the rats eating 5.6 per cent NaCl fell to 50 per cent in nineteen months, with 2.8 per cent KC1 added 85 per cent survived nineteen months, thus exceeding the survival of all rats fed 0.15 to 2.0 per cent NaCI. Half of the rats eating 8.4 per cent NaCl were dead at sixteen months, with the K:Na ratio brought toward 1.0, at twenty-four months. VALUE INDEXES

OF

CERTAIN

OF

VENTILATORY

MECHANICAL

FUNCTIONS

PROPERTIES

OF

AS PUL-

APPARATUS. William F. Miller and Robert L. Johnson, Jr. Cardiopulmonary Laboratory, Dept. of Internal Medicine, Univ. of Texas Southwestern Medical School, Dallas, Texas. MONARY

Previous studies established normal values for the 0.5 and 1.0 second expiratory capacities (TEC) as reliable measures of velocity of air flow. A specific relationship was found between TEC and vital capacity (VC), thus it becomes more useful for purposes of comparison to express TEC as a percentage of VC. This study’ was undertaken to ascertain the effects of various disturbances of respiratory mechanics on TEC and VC so that the usefulness of these convenient measures might be enhanced. Dynamic pulmonary compliance and resistance were measured and compared with TEC and VC; in normal subjects and patients with various pulmonary disorders. VC correlates well with dynamic compliance, thus becoming a function not only of musculoelastic properties but also to a lesser extent viscous resistance. TEC is an extremely sensitive and specific index of changes in pulmonary resistance until such time as resistance becomes very high; then VC also diminishes. Multiple studies were made to demonstrate relationships during the course of treatment. The same correlations were maintained as in individual cases. Thus measurement and interpretation of TEC and VC, in the light of these findings, is a sensitive, reliable and convenient method for evaluating the character of ventilatory disturbances. CANCELLATION GRAMS.

Daniel

OF

ESOPHAGEAL

ELECTROCARDIO-

Ralph F. Morton, William E. Romans and A. Brody. Cardiovascular Laboratory,

for Clinical

Research

Dept. of Medicine, phis, Tenn.

Univ.

of Tennessee,

Mem-

Cancellation of QRS complexes from infratransitional, transitional or supra-transitional electrocardiographic levels of the esophageal lumen was performed seventy-eight times in twenty-seven subjects. Of the procedures 41.0 per cent resulted in excellent, 28.2 per cent in good and 15.4 per cent in fair cancellations (Schmitt’s classification). The corresponding results for twenty-three right arm cancellations were 78.3 per cent, 13.1 per cent and 4.4 per cent, respectively. In decreasing order of excellence the best esophageal cancellations were obtained at the supratransitional, infra-transitional and transitional levels, respectively. Because of the proximity of the lower esophageal lumen to the heart, esophageal cancellations cannot be explained on the basis of the equivalent cardiac dipole hypothesis. Therefore we developed a new theory of cancellation, based on lead field theory and illustrated by electrocardiographic models, which satisfactorily explains the cancellation phenomenon and resolves the paradoxic implication of the equivalent cardiac dipole concept that proximity leads are not selectively influenced by local action currents. The new theory shows that cancellation occurs largely because (a) the networks employed are relatively insensitive electrocardiographic leads, and (b) there is prior assurance of complete cancellation at any two desired instants of the QRS cycle. Therefore the phenomenon does not critically support the idea of cardiac dipolarity. PROTECTIVE DAMAGE

EFFECT

OF

FOLLOWING

HYPOTHERMIA

RENAL

ON

ISCHEMIA

FOR

TISSUE PRO-

John H. Moyer, Charles Heider and Carroll A. Handley. Baylor Univ. College of Medicine, Houston, Texas.

LONGED

PERIODS

OF

TIME.

The employment of hypothermia during surgical procedures has raised the question of a quantitative estimation of the protective effect of hypothermia against tissue damage due to ischemia. Such an estimation is possible in the kidney by measuring glomerular filtration rate and renal blood flow along with water and electrolyte excretion. Observations have been made in which the renal arteries and aorta proximal to the renal arteries were occluded for periods up to three hours. Observations were made on renal function before and five days after occlusion. The procedure was then repeated AMERICAN JOURNAL

OF

MEDICINE