Allan Hemingway

Pulmonary Edema in Oxygen Poisoning.

Conclusion When guinea pigs are placed in an environment of 95 to 99% oxygen at ground level barometric pressure 73 to 75 cm Hg, the animals will develop pulmonary edema as a symptom of oxygen poisoning after 48 hours. The condition becomes progressively worse, and the animals die after 4 to 6 days in the oxygen atmosphere. Lung analyses during severe oxygen poisoning indicate an approximate doubling in lung weight and soluble protein nitrogen. Pulmonary hemoglobin, while quite variable in amount in different lungs, does not increase significantly in the entire lung during oxygen poisoning, but local regions, as shown by histological examination, may be intensely congested.

Alveolar Ventilation Studies Using Mass Spectrometer.

Summary A method of measuring alveolar ventilation utilizing a portable mass spectrometer to determine the rate of nitrogen elimination is described. This test was shown by repeated trials to be rather uniform for each of a group of normal individuals. The range of nitrogen clearance volumes among normal individuals appears to be related to differences in lung volume, and correction for this factor approximates the pattern of values for those tested. Three cases of marked pulmonary emphysema are presented. The results from testing this group in a similar fashion indicate a prolongation of nitrogen elimination in these patients as compared with the normal subjects.

Effect of some atropine-like drugs on swing sickness.

Summary Scopolamine, atropine, hyoscyamine are effective remedies in preventing motion sickness due to swinging whereas homatropine, benzoyltropine and benzoyloscine were less effective and demerol and pavatrine were of doubtful value. None of the remedies, in the doses employed, produced effects on the pulse rate, blood pressure or near point of accommodation. Significant decreases in salivary flow were produced by atropine, hyoscyamine and scopolamine.

A High Frequency Apparatus for Producing a Measured Heat Stimulus in Studies of Physiological Temperature Regulation

The requirements of a high frequency diathermy machine for clinical therapy and for studies of physiological temperature regulation in regard to (1) frequency, (2) measurement of power output, (3) range of power output, (4) efficiency and construction are discussed. To conform with the above requirements a power oscillator of 1000 kilocycles has been built capable of delivering up to 200 watts of high frequency power. A description of the apparatus is given with circuit constants and meter values which have been found useful in physiological temperature studies on animals and human subjects. With this apparatus it is possible to measure the power consumption of a subject treated with diathermy from the voltmeter and ammeter readings.

The Measurement of Heat Production in Diathermy

Resistance and reactance of diathermy patients to alternating currents of varying frequencies up to and including radiofrequencies have been measured with a high frequency Wheatstone bridge. At frequencies greater than one million cycles per second the resistance becomes constant and the reactance and phase angle decrease to zero. Under these conditions the human body behaves as a pure resistance and the heat production in calories can be computed from the formula 0.24 VIt where V is the root‐mean‐square voltage, I the root‐mean‐square current and t the duration time in seconds of the diathermy treatment. High frequency resistances of various parts of the body which are usually treated with diathermy are given.

Angiostomy cannulae for the study of pulmonary circulation.

London(1) used angiostomy cannulae for the purpose of directing hypodermic needles into the larger thoracic vessels. Daly(2) reported the measurement of pulmonary arterial pressure in the unanesthetized dog by means of the London Type cannulae. Johnson, Hamilton. Katz and Weinstein(3) in the same year studied the dynamics of pulmonary circulation by means of hypodermic manometers, the needles being placed in the aorta, pulmonary artery and pulmonary vein. Hamilton, Woodbury and Vogt(4) studied differential pressures in the lesser circulation of the unanesthetized dogs using angiostomy cannulae and hypodermic manometers. Katz and Steinitz(5) developed a modification of the angiostomy cannulae used by Hamilton, and used their cannulae in measuring pulmonary arterial pressures. The purpose of this paper is to report the development of a technic permitting direct access to the atria and large thoracic vessels of unanesthetized dogs under conditions which may be compared to normal. Methods. Two varieties of cannulae were developed and used. The first variety, shown in Fig. 1, a., consists of silver tubes (3 mm outside diameter) fitted with perforated silver plates, one type of which is trough-shaped, to fit over the left pulmonary artery. A second type is flat and oval in shape, suitable for attachment to the left atrium. The length of each silver tube is such that its distal end, the heart serving as reference point, will lie immediately under the skin of the chest wall. The perforated silver plates are made from 2 mm silver stock. The plate attachment that is fitted over the left pulmonary artery is 8 mm long and of sufficient width so that when bent in a semicircle of the correct radius it extends over half the circumference of the vessel. The oval plate for attachment to the left auricle measures 15 mn1 by 10 mm. The cannula tube is fixed in an opening 5 mm from one end of the oval plate.